Document MJkq53RQOgowrD40vyRexzvpx

Distribution on last page ifif! FOR DU PONT USE ONLY "fiCi Report Mo. EX-78-8 Copy No. File 1865 E. I. du Pont de Nemours & Company F & F, Research & Development Division Experimental Station Laboratory Progress Report HIGH SOLIDS AIR-DRY FINISHES PRIMER FOR HAND-CLEANED RUSTED STilVl I 7| > If"' I. 11 DATE ISSUED: WORK DONE BY: AUG 1 ? 1978 R. T. Khanna IARSHALL LABORATO * S 9-5. ^ i\ s i V PERIOD COVERED: September 1976 - October 1977 PROJECT NUMBER: 211517 PREVIOUS REPORTS: None NOTEBOOK NUMBERS: 848E, 878E ABSTRACT Technical requirements for the development of a premium performance primer for rusty steel have been considered. The per formance of inorganic zinc on sand blast cleaned steel would be difficult to match with high solids primers bn hand-cleaned rusty steel using the current primer technology. The best experimental system approaching the target performance is based on a proprietary aluminum flake filled primer, the use Of which is restricted because of unknown toxicity of the key ingredients. Very high solids vehicles capable of curing by multiple mechanisms have been briefly scouted. Prepared by na , Jr. WHEN THIS REPORT IS NO LONGER NEEDED, PLEASE RETURN IT TO THE FILE ROOM, F & F DEPARTMENT, EXPERIMENTAL STATION. i INTRODUCTION The basis of this report is the need for primers with improved corrosion resistance in finishes applications. In particular, one of the long standing need in the maintenance finishes has been a quick drying primer of premium performance for hand cleaned rusty steel. It is anticipated that an attempt to develop a premium performance primer for hand-cleaned rusty steel would form the basis of the metal-primer technology as it would encompass essentially all the critical factors that govern the performance of the primers. OBJECTIVES The overall objective of this program is to provide technological basis for the design and development of high solids, air-dry, low bake finishes for marginally clean surfaces. The immediate commercial target is the maintenance primer for handcleaned rusty steel with field performance level at least 80% that of Inorganic Zinc applied over sand blast cleaned steel at less than 75% of the cost of Inorganic Zinc. SUMMARY AND CONCLUSIONS The performance of primer is a composite function of the vehicle properties and the pigmentation. Most of the recorded efforts at P&F were directed at optimizing the vehicles with the best known pigmentation (lead and chromates). Removal of these inhibitive pigments from primer suggests that a basic understanding of the mech anisms of corrosion and its control is essential before attempting to formulate a new primer. 9 A fundametal review of the mechanisms of protection against corrosion by organic coatings indicated that a) organic vehicles alone provide only limited protection, b) excessive water is always present at the metal interface, c) the rate of oxygen permeation determines the corrosion rate and d) a good primer contains inhibitive pigments, corrosion inhibitors and/or sacrificial metal. e Sacrificial corrosion protection afforded by "Inorganic Zinc" is difficult, at best, to match with other modes of corrosion control (barrier and inhibitor) commonly employed in primers based on organic vehicles. Among the epoxy primers studied, the best protection is obtained with zinc flake filled system. However, the presence of large amount of zinc results in poor intercoat adhesion under Imron polyurethane enamel. A tie-coat of zinc-free epoxy vehicle (topcoat or primer) may enhance the utility of the system and needs to be evaluated. DUP030014249 2 A new lead for the design of primer for hand-cleaned steel has been identified. It involves the use of Accelerator 808 dis solved in high boiling acrylic monomers as penetrant and aluminum flake filled Hypalon 30 as topcoat. Preliminary results confirm that the in-situ cure penetrant/primer based on an extension of "Quick-set" acrylic adhesive technology provided excellent protection approaching that of inorganic zinc. In order to exploit this lead commercially, it is essential to a) develop a non-toxic in situ cure penetrant and b) higher solids topcoat capable of initiating free radical polymerization of the penetrant. No attempt has yet been made to explore or confirm these hypotheses. A comparison of clear vehicles made from current alkyds, epoxies and moisture-cured aromatic isocyanate prepolymers suggests that a) epoxies and moisture cured aromatic isocyanate prepolymers are comparable in providing protection, epoxies having better blister resistance, b) alkyds soften excessively and disintegrate by film swelling. The use of aromatic isocyanate prepcilymer is limited because of their toxicity and high water sensitivity during manufacture, storage and application. Low molecular weight epoxies cure with Ketimine, polyamide and phenolkamine resins at ambient temperature and provide high solids cure system ( 60% volume solids). None of the modifications to incorporate inert pigmentation (talc and micaceous iron oxide), inhibitive pigmentation (barium metaborate, and zinc molybdate), inhibitors (Sicorin AZ) and clear penetrants improve the primer performance to that of inorganic zinc on sand-blast cleaned steel. Brief scouting effort for a novel ambient cure chemistry has resulted in a hybrid-cure high solids system ( 70% volume solids). It comprises of in situ cure of an air drying vehicle (preferably with some residual hydroxyl functional groups) in the presence of both reactive monomers (trimethylolpropanetrimethacrylate, 1,6hexanedioldimethacrylate) and isocyanate prepolymers (Desmodur N-75 or E-21). Although prototype primer compositions tended to be too hard and brittle with very good corrosion resistance on rusty steel, the rate of cure and flexibility can be varied to suit maintenance application. Further effort is necessary to explore the system and establish regime of operation for the development of a functional product. ACTION TAKEN OR PROPOSED Three exposure series based on the systems studied in this work have been issued for field exposure at Beaumont, Texas. The results of these exposures would be summarized separately at the completion of the tests. Two prototype primers are recommended for further development and field exposure: DU P030014250 3 a) an alkyd-acrylic-urethane hybrid-cure primer (modify for improved flexibility). b) zinc-flake filled epoxy primer with intermediate tiecoat of zinc-free vehicle (eliminate intercoat adhesion with zinc-flake containing primer). PATENT SITUATION FF-3273 - Request for Filing a Patent on a proprietary primer composition based on "Quick-Set" in-situ cure penetrant has been made. Further action is deferred because of insufficient interest in the product at the present time. Request to file for a patent on alkyd-acrylic-urethane high solids ambient-cure composition is deferred pending full assessment of its potential to meet F & F needs. PUBLICATION STATUS There are no plans to publish any of the results from this project. TOXICITY/ HANDLING AND SAFETY CONSIDERATIONS Given all favorable conditions, if a successful high solids product (= 80-90% performance of inorganic zinc) is developed, it is highly probable that it would involve a) low molecular weight, re active, multi-functional monomers, additives or diluents and b) some toxicological limitation on their use as spray applied primer. Primary ingredients of potential handling and toxicity hazards in the present study have been a) Epoxy curing agent Ketimine H-3 which produces diethylenetriamine (DETA) on exposure to moisture. Ethyleneamines such as DETA are known to be skin-irritant and sensitizers and should be handled in a manner similar to that of Imron line of finishes. b) Molybdate containing pigments. There is some concern about the toxicological safety in the use of molybdates and require protective equipment to eliminate particulate hazard. c) Corrosion inhibitors are of a variety of forms and some of their unique structures could also pose toxicological questions such as in the use of lithium benzoate, zinc dibenzylthiocarbamate and*amines. d) Isocyanate prepolymers, such as Desmodur N-75 and Desmodur E-21, are moisture reactive resulting in a variety of products with questionable toxicity. Desmodur E-21 in particular requires attention in that its reaction byproduct and intermediates can be highly undesirable aromatic amines. One must be alerted to metabolic influences when moisture-cured isocyanates are considered. DUP030014251 e) The use of polyfunctional methacrylate monomers requires full assessment of the level of their use in the finished formu lation and its influence in skin-sensitization under conditions of use. It is recommended that any high solids formulation for the rusty steel be tested thoroughly for toxicological data so that appropriate protective equipment could be specified for field application conditions. DUP030014252 4a TABLE OP CONTENTS INTRODUCTION .................................................................................................................... OBJECTIVES ....................................................................................................................... SUMMARY AND CONCLUSIONS .................................................................. ACTION TAKEN OR PROPOSED ...................................................................................... PATENT SITUATION .......................................................................................................... PUBLICATION STATUS.............................................................................................. TOXICITY, HANDLING AND SAFETY CONSIDERATIONS ............................. DISCUSSION ......................................................................................................................... I.BACKGROUND ................................................................................................................ II. SPECIFIC CONSIDERATIONS FOR PRIMER FOR HANDCLEANED STEEL.................................................................................................. Ill. STANDARD OF PRIMER PERFORMANCE ....................................... IV. DEVELOPMENT STRATEGY.......................................................................... A. Role of Vehicle .............................................................................. B. Role of Inert Pigmentation .................................................... C. Role of Inhibitors and Inhibitive Pigments in Primers ................................................................................................. D. Other Approaches to Primers for Hand-Cleaned Steel ............................................................................................................... V. CONCLUSIONS AND RECOMMENDATIONS ............................................... REFERENCES ........................................................................................................................... TABLES I. PENETRANTS FOR IN SITU CURE ALUMINUM FLAKE FILLED HYPALON 30 ........................................................................................................, II. HIGH SOLIDS AIR DRY ACRYLIC MODIFIED ALKYD PRIMERS WITH ISOCYANATE PREPOLYMERS ............................................................. APPENDIX I ............................................................................................................................ APPENDIX II ......................................................................................................................... APPENDIX I.IIA ......................................................................... ........................................ APPENDIX IIIB .................................................................................................................. piiin ijime .........................................i Al^PP!5^131X 111D ........ jPENflOIX[ I*\^ ............................................. APPENDIX V APPENDIX VI eoeea*90&ee*e Page 1 1 1 2 3 3 3 5 5 8 9 10 11 12 14 15 16 19 20 21 22 24 26 28 37 41 43 62 66 DU P030014253 5 DISCUSSION I. BACKGROUND High performance primers are identified by the presence of red lead, chromates or zinc dust in most instances. Yet there is no completely satisfactory product based on these pigments and known vehicle systems that provides long term protection on handcleaned rusty steel. The history of research efforts on "new" primer for this end use in P & F is long (Appendix I) and yet the need for a quick-drying, premium performance primer on hand cleaned rusty steel remains. Red lead pigment in linseed oil alone, or in combination with alkyd resins has been the standard maintenance primer for use on hand cleaned steel. The system is slow to dry and it requires a quality topcoat for good protection. Further, the application of high quality, premium performing topcoats (such as Corlar and Imron) requires extended recoat interval over such primers and this delay in field use conditions is economically undesirable. The primary effort in the development of new primer was in most cases concentrated on the vehicle development. Major raw material suppliers and new vehicle manufacturers also concentrate on promoting new resins for improved performance of primers. Such vehicle modifications are the easiest to incorporate and provide "proprietary" primers when formulated with corrosion inhibit!ve pigmentations. However, the design of new vehicles was, on the large part, aimed at improving adhesion, drying and weathering characteristics with incidental improvement in corrosion performance. On the other hand, considerable strides have been made in the science of corrosion and extensive literature exists ( 1-3) An analysis of the corrosion phenomena suggests that the protection can be designed by either one or the combination of the following: i) Physical Barrier (high film build) ii) Electrochemical Barrier (sacrificial anode) iii) Chemical Barrier (inhibitors) A brief discussion of each of the controlling phenomena would follow to bring the problem of priming rusty steel surface in perspective. Physical Barrier: One of the main modes of protection of steel from aggressive environments by polymeric coatings is of isolating the two by means of a physical barrier. In systems protected purely by this mechanism, the rate of attack on the metal is then governed by the fundamental laws of diffusion and transport DUP030014254 6 of oxygen, water and corroding ions through the coating to the metal interface. An examination of the permeability of organic systems (Appendix II) indicates that most of the polymers are too permeable to water and oxygen. Various investigators have examined this problem in detail and concluded that a) organic vehicles alone provide limited protection, limited by high permeation of oxygen, water and ions because of molecular interactions, solubility and voids. b) excessive water is always present at the interface and it causes adhesion loss as a prerequisite for the start of the corrosion process. c) oxygen permeation is the slowest process. It controls the rate of corrosion and determines the acceptable life of the coating. d) inorganic coatings such as those formed in metal treatment processes have much reduced permeability but their utility is limited to thin film applications because of excessive brittleness in heavier builds. Advantage is taken in maintenance finishing of this mode of control by providing as high a total film build as economically possible, often between 5-10 mil dft. Most inert polymeric vehicles do not provide adequate physical barrier at this level of film build and require added protection by other modes of protection. Electrochemical Barrier: It is well established that corrosion in aqueous electrolytes is an electro-chemical process. The corroding metal leaves the metallic state at anodic areas and consumes some constituent of the electrolyte at the cathodic areas. The rate of corrosion corresponds faradiCally to the current passing between the anodes and cathodes: At The Anode: M (metal) --> M++ + 2e At the Cathode (in acidic media) 02 + 4H+ + 4e --P 2H20 2H+ + 2e --> H2 (g) (in neutral or alkaline media) 1/2 02 + H20 + 2e --> 2(OH) These simple reactions are the basis of control by electrochemical and inhibitor means. In a cathodic control, the rate of corrosion is controlled by the rate at whichthe cathodic reaction could take place. In most cases of cathodic control, oxygen diffusion controls DUP030014255 7 the corrosion rate. The rate limiting step in an anodic control system is the dissolution of the metal which could be influenced by partially obstructive films on the metal. Corrosion, being an electrochemical phenomenon, is accompanied and accelerated by the passage of very small electric currents between the corroding metal and any other metal with which it is in electrical contact or between different areas on the surface of the corroding metal. Two requisites for these currents to flow are: a) A potential difference either between the two pieces of metal or between the different parts of the same piece. Potential differences sufficient to cause current flow arise from very small local inhomogeneities in the chemical constitution of the surface such as phase differences.across a grain boundary, inclusion of sulfur, phosphorous and chlorides. b) Presence of moisture or other electrolyte on the surface to act as a conductor for the current. The direction of the current which flows when two metals are brought into contact in the presence of an electrolyte depends on the relative positions of the metals in the galvanic series, Anyone of these metals/alloys" will theoretically corrode while offering protection to any other which is lower in the series, so long as an electrical continuity is main tained. Thus in the case of zinc and steel, a corrosion current will flow from steel to the zinc so that zinc becomes an anodic electron producing area while the steel is cathodic electron consuming. The zinc, therefore corrodes in performance to the steel and in so doing protects the steel surface. This type of "sacrifical or cathodic protection" occurs when zinc coatings on steel surfaces are subjected to mechanical damage, such as scribed mark with metal cutting tool, whereby the continuity of the zinc coating is broken and the steel surface is exposed. This important property of zinc as a coating material (or a major coating ingredient), is also possessed, although to a lesser extent by aluminum. Direct application of zinc in processes such as hot dip galvanizing, zinc plating, spray metallizing are widely practiced for the protection of steel. However, zinc-rich coatings are used in the maintenance finishes where such processes can not insure full protection over the entire life span of the structure. Zinc rich coatings are often highly filled with zinc dust (80-95% by weight) and can be defined by their electrical conductivity. The interesting fact to note is that zinc rich primers perform universally much betfer than the best non-zinc primer in most DUP030014256 8 environments with the exception of highly acidic or alkaline environ ments . The sacrificial protection afforded by zinc is so overpowering that any system designed to replace zinc must provide essentially complete protection. It is, thus, important to stress that any attempt to make a primer for rusty steel must not exclude the use of zinc from consideration. Chemical Barrier; Protection against corrosion requires that the continuity of the electrochemical cell be disrupted. In order to inhibit corrosion, it is necessary to stop the flow of current, either by suppressing the cathodic or the anodic reaction or by inserting a high resistance in the electrolytic path of the corrosion current. These three modes of control by suitable chemicals form the basis of inhibitor technology. Extensive literature is available that focuses attention to this mode of corrosion control in various industries? such as boiler-feed water, cooling water, oil drilling fluids, engine lubricants, metal cleaning and metal treat ments. However, the use of inhibitors as a part of the coating is only recently recognized. The toxicity concern about the most widely used chromates for corrosion control has focused attention of various investigators to search for non-toxic replacements. It is antici pated that these efforts would identify Specific inhibitors for the desired applications and most likely cannot offer essentially universal protection afforded by chromates. The science and technology of corrosion inhibitors has been summarized in the Appendix IV and discusses fundamental considerations for exploiting this technology. The successful development of non-zinc (or aluminum) primers with predictable performance requires understanding the role of inhibitors in the coating. Needless to stress that this is the least under stood phenomena in the coating industry. II. SPECIFIC CONSIDERATIONS FOR PRIMER FOR HAND-CLEANED STEEL The problem of preventing corrosion in steel is still present in the case of hand cleaned rusty steel. The marginal cleaning of the surface creates additional difficulties: a. The surface profile of hand cleaned surface depends on the extent of cleaning and could average between 4-6 mils. A very fluid gap-filling primer would fill in the valleys and provide only marginal coverage of the peak areas. A thixotropic composition provides some what better control of dry - film thickness at the expense of reduced penetration and gap filling efficiency. b. The rust and mill scale can provide good protection when impregnated with good wetting primer vehicle. Essentially, complete arrest of the corrosion process by the primer is essential and the primers are noted to fail precipitateously (peel-off) once the under film corrosion starts. This reasserts the importance of using zinc-rich or primer with good rust inhibitors. This is con trasted with primers on clean sand blasted surfaces where corrosion DUP030014257 9 can be tolerated to a higher extent before complete failures occur. Most coating systems, except for zinc-rich primers, do not offer such protection and are limited by the state of the coating technology. c. Rusting in a chemical environment leaves contaminations that may accelerate corrosion. The level of contamination is deter mined by the amount of rust and mill scale left after hand cleaning. The type of contamination is influenced by the environment in which rusting occurs. An inhibitor capable of making such contaminants harmless would add to the service life of the primer. d. The porosity of the rusty surface tends to extract the vehicle out of the primer resulting in an uneven distribution of the pigment in the primer. The highly filled primers (close to CPVC) could result in too porous primer (dry look) and fail because of large voids through which water, oxygen and corroding ions may migrate readily. It is therefore desirable to pigment the primer at 30% or lower PVC. e. In field applications, the primer for rusty steel requires it to be applied not only to all rusty surface but also to partly rusted and partly residual paint bearing surfaces. This type of field substrate conditions are variable and difficult to reproduce. The success in the commercial use depends on the versatility of the primer application to a variety of surface conditions. m. STANDARD OF PRIMER PERFORMANCE The current standard of primer performance in maintenance painting is Inorganic Zinc (IOZ) applied over "white*" metal (sand blast specifications SSPC-10). Following characteristics are considered necessary for a suitable primer for hand cleaned steel: Performance level 80-90% that of IOZ (applied on "white" metal) Rapid dry and cure for recoat in less than 4 hours with topcoats containing active solvents Non-chromate and lead free pigmentation High solids (preferably as high as 70-80% volume solids) with air pollution conformance regulatory classification being such that it may be used anywhere in the U.S. Applied cost at not more than 75% than that of IOZ. A unique proprietary product would command both a premium price and a large market share DUP030014258 10 IV. DEVELOPMENT STKATEGY Abbve discussion of the corrosion controlling mechanisms, the special problems of painting rusty steel and the failure of numerous attempts to make a commercially successful primer indicates that the target performance of 80-90% that of Ganicin 347-931 (IOZ) on sand blasted steel would be difficult to achieve. It was there fore necessary to consider a developmental strategy so that incremental improvement in the performance can be identified. Following is such a scheme for primer for hand cleaned steel. a. Develop chromate-free primer equivalent to the performance of Corlar 825-8031 on blast cleaned steel. b. Assess feasibility and develop high solids analog of (a) . c. Develop chromate-free, zinc-containing primer equiva lent to the 80-90% performance of Ganicin 347-931 on blast cleaned steel (target performance). d. Assess feasibility and develop high solids analog of (c) . e. Develop proprietary zinc and chromate free primer for target performance. f. Assess feasibility and identify high solids analog of (e) . This sequential execution of the program is logical, more realistic, likely to provide a technical basis for widely applicable primer technology and may offer primer candidates capable of direct substitution in place of current commercial analogs for use over rusty steel. These intermediate levels of performance were not judged to be good enough for introducing new primer for rusty steel. Also, time and resource constraints could not justify completion of each of the intermediate steps. The objective of the program was, therefore, to attain (f) without necessarily developing inter mediate candidates. The development of primers for maintenance finishes has been more an art than a science and there is not defined procedures for identifying a primer system. Following developmental strategy was adopted to ensure a balance between longer term D.I.E.B. effort of providing a technological basis and short term I.E.B. effort to develop a functional primer for rusty steel. DUP030014259 11 a. Assess the role of common vehicles such as alkyds, epoxies and urethanes in primers. b. Establish the role of inert pigments in the selected vehicles. c. Evaluate inhibitive pigments in combination with inert pigments in the preferred vehicles. d. Formulate prototype primers and compare their perform ance characteristics with current commercial primers, including Ganicin 347-931 (IOZ). e. Evaluate inhibitors (non-pigment additives) and compare their effectiveness versus non-toxic inhibitive pigments. f. Evaluate the role of reactive and nonreactive penetrants in prototype printer vehicles. g. Select a preferred candidate and assess marketability of the product based on its performance, application characteristics, cost and profitability. A. Role of Vehicles An exposure series (Appendix IIIA) was prepared from a number of commercial primers (as controls) and their clear vehicles, experimental epoxies cured with a variety of curing agents and aromatic isocyanate prepolymer (Desmodur E-21). Three substrates used were (a) polished clean cold rolled steel? (b) hand cleaned rusty cold rolled steel and (c) hand cleaned rusty hot rolled steel. The primers were applied at 2-mil dft with 2-mil dft topcoat of 369Y-67641 and exposed for 500 hours salt spray. Low film thickness and shorter exposure time was considered to be desirable to differentiate between various systems. Following observations were made: Corlar (825-line) and Dulux 67-746 are good primers for clean steel showing very little creepage from the scribed line but poor on rusted steel. Corlar clear vehicle shows severe undercutting at the scribe on clean-cold rolled steel (C-CRS) but reduced visible under cutting on rusted panels, indicating that a combination of lower viscosity vehicle and the presence of rusty layer protects better than the commercial pigmented analogs. While the differences were small, it was noticeably obvious that the clear vehicle had improved penetration and wetting of the rusty layer compared to the pigmented analog. DUP030014260 12 Clean polished steel surface is more active and tends to corrode faster than rusty steel. This trend was seen in major part of the series. Dulux clear vehicle shows complete failure, essentially disintegrating badly over the three substrates. The presence of chromate pigmentation in both the Dulux primer 67-746 and Corlar 825-8031 clearly offers marked corrosion protection and film reinforcement. The alkyd films are still very weak and saturated with water as compared to Corlar epoxy-polyamide vehicle. Inorganic zinc (Ganicin) 374-931 control on C-CRS was perfect with no failures at all. The clear vehicle does not form film on steel. Distinction must, therefore, be made between organic primers filled with pigments and inorganic primer where zinc is the reinforcing part of the matrix. & Experimental epoxies were all comparable in performance on all the substrates. Ketimine (H-3), aromatic amine adducts (Araldite 830 and Araldite 850) and polyamide (Versamid 280B75) were selected for further testing of pigmented compositions. m Aromatic isocyanate prepolymer (Desmodur E-21) also performed equivalent to the epoxies but exhibiting slightly greater tendency to blister. The role of vehicle is thus to provide primarily the application latitude, cure, dry time, good adhesion etc. and only incidental improvement in corrosion protection. It was expected that suitable pigmentation can upgrade the performance of high solids experimental systems. B. Role of Inert Pigmentation Low molecular weight epoxies cured with ketimine, poly amide and polyamine (Appendix IIIB) were pigmented with talc and micaceous iron oxide. An exposure series No. 24216 with commercial control was prepared. The results of salt spray cabinet testing after exposure for 1500 hours showed the following trends; e Dulux 67-746 on C-CRS (control, #6-1) and R-CRS and R-HRS (#6-11) shows dense blistering both in primer and topcoated section. The primer film is very weak and soft because of excessive water retention. 9 Corlar 825-8031/VG-88339 on C-CRS (control #6-2) performs excellent but fails on rusted panels (#6-12) by dense blistering and overall rusting. DU P030014261 13 Low molecular weight polyamide Emerez 1514 cured epoxy primer (848-E-139, panel #6-9) failed by dense blistering, probably because of inadequate cure or application. All other experimental candidates on rusted panels exhibited comparable performance to that of Corlar 825-8031/VG88339 on C-CRS. Following candidates with talc and micaceous iron oxide pigmentation were judged to be slightly superior to other experi mental candidates: 848-E-135-3C Epoxy/Ketimine Adduct (#6-6) 848-E-141 Epoxy/Polyamide Adduct (#6-10) 848-E-137 Epoxy/Polyamide Adduct (#6-7) These would be studied further. Ganicin 347-Y-931 continued to show excellent performance on both SB-HRS and R-HRS. Aluminum flake filled epoxy/ketimine adduct primer shows excellent performance. 20% PVC appears to be adequate for primers over rusty steel. A candidate (848-E-144, panel #6-14) pigmented at 30% PVC showed adhesion loss between primer and Imron topcoat when exposed to salt spray. Re-examination of the experimental test panels after months of storage showed extensive under film rusting. Epoxy/ phenalkamine (848E-138) cured system did not show this failure and was included for further studies with inhibit!ve pigments. 3 . It can be summarized that a purely physical barrier of cured epoxies filled with talc and micaceous iron oxide pigment at nominal primer thickness of 4 mil does not afford the needed pro tection. It is due to the absence of both chemical or electro chemical corrosion controlling mechanisms. It is interesting to observe thatlOZ (Ganicin 347-931) performs excellent on SB-HRS and relatively good on R-HRS, again confirming the dominant role of zinc in controlling corrosion even though it is not in direct physical contact with the steel but e1ectrochemically connected by the conductive electrolyte in the porous rust. It must be recognized that zinc retains its effectiveness both in small concentrations and when isolated from steel by short distances. However, direct electrical contact of zinc with metal will decidedly improve corrosion performance. DUP030014262 14 A separate study (Exposure Series #24217) was conducted to examine the influence flake pigementation. The flake pigments included are shown in Appendix IIIC. Ganicin 347-Y-931 was used as control. The results of 1500 hours salt spray indicate that a) inert flakes such as glass, mica and talc are not suitable as the pigments for primers for hand cleaned rusty steel in the vehicle examined, b) the system with zinc-flake shows good perform ance on C-CRS with spot failures on R-HRS suggesting that the zinc flake can potentially be used in organic vehicles to provide both barrier and electrochemical protective control, c) aluminum flake containing epoxy/ketimine primer fails by blistering at the scribe and edge rusting. It thus becomes apparent- that- although epoxies are common ly used primer vehicles for clean substrates, they are poor performers over rusty steel with inert or flake pigmentation, the-substrate being continuously variable shows variable performance. C. Role of Inhibitors and Inhibitive Pigments in Primers Inhibitors offer chemical means to intercept corrosion reaction and impart a rate limiting step, thereby controlling the useful life of the coating. Numerous literature references (Appendix IV) suggest a variety of inhibitors but their utility in paints has not been established. Inhibitor technology, as applied to primers is in its infancy, primarily because of dominating impact of chromates as to their availability, effectiveness and price. There is sudden realization throughout the industry of the need to understand and exploit the inhibitor technology when the use of chromates is severely curtailed by law. The technology of inhibitors appears critical in the development of new high performance metal protective systems, especially where low cost alternatives to the use of zinc metal is considered. However, a meaningful understanding of this technology would require concerted effort on an on-going basis and was beyond the scope of current effort. Some of the recommendations are outlined in Appendix IV. Of the large list of potential inhibitors only two were examined in the epoxy/ketimine primer at 20% PVC (talc and micaceous iron oxide) with 10 phr of the inhibitors: Zinc bibenzyldithiocarbamate (Arazate) and Lithium Benzoate The results of salt spray testing (1600 hours) confirm that both the inhibitors considerably retard the underfilm corrosion to a point where the performance of epoxy primers on hand cleaned rusty steel can be compared to that of Corlar 825-8031 on sand blasted steel. Since these two chemicals were not desigiied for use in this manner, there is reason to suspect that both contain water soluble salts which introduce water sensitivity in the coating as evidenced by very fine blisters. Both these chemicals appear as effective inhibitors in the primers examined, though not entirely satisfactory for use in any commercial system. DUP030014263 15 Initial success with the two selected inhibitors suggests that a wide variety of chemicals can behave as inhibitors. It is recommended that a separate study of inhibitors for use in alkyds, epoxies and urethanes be conducted. Identification of electrochemically effective inhibitors can provide proprietary position as well as offer system at the lowest cost. The primary emphasis by pigment suppliers has been the introduction of non-chromate corrosion inhibitive pigments. A list of such pigments is included in Appendix III. Most of these are not as uniyerally applicable as chromates and show varying degree of effectiveness in common primer vehicles. A number of F & F programs have examined these new pigments. Jim Courtright(4) in his effort to develop chromate-free analogs of Dulux and Corlar primers found barium meta-borate (W-178, Busan Mil) and zinc molybdate as the preferable pigments in the epoxy primers. These two pigments and two prototype inhibitors were therefore included in a composite one shot effort of examining the performance of the epoxy primers with the best known pigmentation and all other approaches to primers for hand-cleaned steel. The results of this exposure series are summarized in the following sections. D. Other Approaches to Primers for Hand-Gleaned Steel Penetrant-Primer Systems: Linseed oil penetrant under an alkyd (Dulux) or epoxy-polyamide (Corlar) primers for application on hand-cleaned rusty steel is frequently used. It is not clear whether this really upgrades the system performance. This mode of primer application i.e. mist coat of penetrant followed by primer topcoat was used to an advantage in a iftodification of "Quick-set adhesive system" (7). The primer system is based on Accelerator 808/acryiic monomer blend, used as penetrant, which on contact with aluminum flake filled Hypalon rubber initiates insitu free radical polymerization of the acrylic monomers. An exposure series was prepared based on few modifications. Following conclusions were drawn based on 2000 hours salt spray exposure. Penetrants based on 10% Accelerator 808 and 90% acrylic monomers or epoxy diacrylate (XD-9002) show excellent performance. The blend should be homogeneous for optimum effectiveness. For spray application the solids level of penetrant can be varied between 20-60% (by wt.). Two penetrants were noticeably superior: Reference: 878E-39-3: Acc-808/BMA/XD-9002//10/60/30 @ 60% S 878E-39-5: Acc 808@/XD-9002//10/90 at 43% S Aluminum flake filled in-situ cure Hypalon primer has shown outstanding corrosion resistance meeting the performance objectives of the program (80% that of Ganicin on sand blast cleaned steel). DU P030014264 16 - The system is essentially of low solids { 30% weight solids) and could pose toxicity hazard of spray applying Accelerator 808/monomer blend. The use of aluminum flake in chloro--sulfonated polymer has also been questioned as to its potential of spontaneous exothermic reaction. This system is, therefore, no longer under consideration. However, it is likely that non-toxic system based on this approach can be identified and provide a proprietary patent position (Appendix V). b. Modification of Existing Productss The present primer for hand cleaned steel is Dulux 67-746(chromate-containing linseed oil modified alkyd). The main weakness of this primer in affording extended protection lies in its vehicle being too easily saponified and poor integrity. A lead, based on the work of HeibergertS) and Leavell(6), Qf modifying air-drying alkyds with acrylic monomers (e.g. Trimethylolpropane trimethacrylate) was studied briefly to upgrade the performance of this primer. 50% dilution of Dulux 67746 with TMPTMA gave a 77% volume solid primer exhibiting very good performance on rusty steel after 1500 hours salt spray. The two limitations were recognized. a. Continuation of the use of chromate pigmentation, and b. Slow dry (16-24 hours) A variety of other modifications have since been made (Appendix VI) with varying degrees of pot life and dry times in systems free of chromate pigmentation. It was observed that considerable formulating latitude in controlling the cure, dry time and pot life of their acrylic modified oxidativity air-drying vehicles exists. Scouting effort (Table III) has shown that the anti-skinning agents (MEKoximes) and polyisocyanate prepolymers in the presence of driers provide a multitude of cure mechanisms to control the pot life and dry time of the primer. These high solids vehicle modifications are of little utility unless inhibitive pigments and inhibitors can be incorporated to give a formulated primer. Prototype primers with the best known pigmentation were therefore prepared (Exposure series #24323) to compare their performance on hand cleaned steel relative to Ganicin 347-931 on sand blast cleaned steel (Appendix HID) . V. CONCLUSIONS AND RECOMMENDATIONS The performance of a primer is a composite function of the vehicle properties and the pigmentation. Most organic vehicles alone can not provide adequate corrosion protection because of excessive water and oxygen diffusion and lack of corrosion inhibitive properties. DUP030014265 17 Inorganic Zinc (Ganiein 347-931) on sand blasted steel is the premium performance primer and can not be compared with most primers considered in this report with the following exceptions! (a) Zinc flake 21HF filled epoxy (75% weight solids, 63% wt. zinc flake at 30% PVC) at 80% the cost of inorganic zinc. (b) In-situ cure Accelerator 808 (pentrant) activated aluminum flake filled Hypalon 30 primer (27% weight solids) at 80% the cost of inorganic zinc. Inhibitors can upgrade the performance of primers by retarding the corrosion kinetics. Prototype inhibitors were functional in epoxy primers at 10 phr. High potency inhibitors may be identified but it remains doubtful if the performance level of IOZ can be achieved entirely by their use. Epoxy primers without chromate pigmentation are limited to a maximum of 60% volume solids for spray applications. The vehicle cannot penetrate and wet the rusty pores adequately to arrest under film corrosion starting at the scribei Highly effective chromate free inhibitors or the presence of sacrificial zinc in the coating is essential to approach the target objective of 80% performance of Ganiein 347-931. A high solids in-situ cure primer with built-in penetrant is derived from Dulux 67-746 modified with TMPTMA (50% by weight) to yield a high solids (77% vol. solids) primer with performance level better than the unmodified alkyd primer. Further modification with other acrylic monomers and isocyanate prepolymers have been discussed as a means of controlling dry time, pot life and cure of the primer. There is definite need to refine the prototype formulations for optimum cure and compatibility before any commercial analogs could be developed. Epoxy/phenalkamine system provides a more complete cure (vs Epoxy/ketiraine) as judged from the increased blister resistance of the primers with the same inert pigmentation. This, of course, yields primer of less than 60% vol. solids. There is no basic understanding of whether a particular inhibitive pigment would perform satisfactorily. In addition, most of the available information refers to the case of priming sand blast cleaned steel and of limited value to the present study. A primer for hand cleaned steel requires absolutely perfect corrosion control system* such as inorganic zinc on sand blasted steel, to be effective. The technology of developing such a product requires a systems approach to incorporate all the corrosion controlling phenomenon. Such an effort could not be made for the lack of understanding of both, corrosion control and new,air-dry high solids curing systems.. DU P030014266 18 The technology of inhibitors is in infancy and holds promise. There is no active program in F & F and chances of success are limited. It would be worthwhile to monitor field developments closely, particularly the reports from Inhibitor Technology Subcommittee of National Association of Corrosion Engineers. Most of the developmental work in the past and in the current program was limited to common primer vehicle chemistries. An added awareness of the importance of the corrosion inhibition process suggests that once the technology of chemical control of corrosion is established, it would be logical to design primer vehicles with built-in inhibitor functionalities. The success with the use of Accelerator 808 confirms to its multiple role as a penetrant, free radical initiator, wetting agent, adhesion promoter and corrosion inhibitor. Although the toxicity of spray applied Accelerator 808 is not established, it would be desirable to consider potentially less toxic analogs such as that made from dodecylamine and butyrldehyde. This study has barely touched the main issues important in the development of the primers. It has not evolved the solutions but only identified the areas of expertise needed to develop a strong product and proprietary advantages. RTK:1ms DUP030014267 - 19 REFERENCES 1. Shreir, L. L., Corrosion, Volumes 1 & 2. 2. Uhlig, H. H., Corrosion & Corrosion Control 3. Collected lectures on Corrosion & Protection of Metals, Published by American Elsevier. 4. J. R. Courtright. Report No. TF-76-9. 5. P. H. Heiberger, Report No. TF-78-1. 6. K. H. Leavell, Report No. EX-78-1. 7. J. M. Craven, Report No. EX-75-21C. DUP030014268 - 20 - TABLE I PENETRANTS FOR IN-SITU CURE ALUMINUM FLAKE FILLED HYPALON 30 Reference: 878E-39Accelerator 808 Butyl methacrylate 23 4 5 10 10 10 10 90 60 Lauryl methacrylate Epoxy diacrylate, XD-9002 MEK Cellosolve Acetate Xylene Total % Solids (wt.) Appearance 20 30 100 250 40 Clear 30 6 30 30 166 60 Clear 60 30 6 30 30 166 60 Cloudy 90 18 30 90 238 42 Clear QUICK-SET CURE "Reactive, In-Situ Vinyl Cure" Lead; Quick-Set Adhesives Characteristics: Apply Activator to one surface (even oily) Apply Adhesive to the other surface (Hypalon in MMA/MAA) Join, Exclude air Set time 5 minutes Cure up to 25 mils* Bad Odor Toxicity (MAA) 20/30 Coating Application: Penetrants: Accelerator 808 Epoxy Diacrylate Reactive diluent non-toxic) Apply wet coat XD-9002 (non-volatile, low volatility solvent, Primer: Hypalon 30 Aluminum Flake, W-128 Hydrocarbon Solution P/B 67/100 Apply Over Wet Penetrant DUP030014269 HIGH SO LIDS A IR DRY AC R YLIC M O D IFIE D ALKYD PRIMERS W ITH ISOCYANATE PREPOLYMERS *w ith a d d itio n a l d rie r 21 CM I VO o rH CM I O CM hi tH CM I o 00 rH 00 >3' o CM t--I VO ON CO I rH H CM I o 00 00 0 0 M* "3* CO rH VO CTi <o 1 rH VP 1 in ON VO 0 CM O CM O CM O O in in rH u\ r-f o S * O A CD in o in o rH 0 CM rH CO a o u CM cn aS rH CD 1 o o in co rH * CM r-l o co in + in O CM CO I'' rH rH o co CM oo 0 o in CO "+ in o oo h no ^ a m "M* VO rH M M rH *3* in rH rH o I 00 VO VO I o co in 00 o -vr CO rH II 03 W VO 00 oo r- r- oo U CO CD i <d o cn w8 CO as oo 0 VO 3 M r~ tn sp . 1 oo iH rH oo vo I M vo 00 c- lH rH l 1H CD a) o f' r- H M o vo vo s S CO G CM Q CD CD w u oQ 1 SH *3 X X 2 s O m >i 3CD o 8 EH <A g w 1H rH rH H 1 vo O Q OJ 05 H < 3 Q 3 a u ft S EH Q > Q, Oi rH da m in Hi in 0 CD M* rH r- *3* in o CM A cn in in 0 0 rH r~- r** CO 00 Tjv 00 CM CM CM CM A rH 4J Q > 00 CQ to pu S3 X ob rH CO rH CM o m1 H CM i rH XjV 8- ON >* l cn <3> O CO |: | & | 03 O > 5a1 8 W <#> o H c d o p 8 a (0 rH H 05 Eh EH oX rH > ft H s SH a O2 DUP030014270 cc: S. G. Smith - F&F - Marshall Laboratory Ce n t r a l Re p o r t In d e x 3211 CENTRE ROAD BUILDING Wil min g t o n , De l a w a r e <9898 Information Systems Department - 22 APPENDIX I November 12, 1975 CRI Ref. No. W-75-5342 Request Rec'd. November 6, 1975 TO: R. T. Khanna Fabrics & Finishes E 293/202 FROM: P. J. Sazegar, Supervisor 3219 Centre Road Building Ext. 4113 MAINTENANCE PRIMERS: FABRICS AND FINISHES DEPARTMENT REPORTS ONLY Eighteen summary and conclusions are enclosed on the title subject. Departmental Rept. No. Departmental Rept. No. R-56-45 R-62-26 R-62-33 R-62-43 R-63-6 R-66"58 R-68-89 RM-62-5 RM-63-2 R-62-16 R-62-32 R-62-34 R-62-78 R-64-31 R-68-29 R-69-38 RM-62-11 SM-64-7 S. G. Smith sent you thirteen references which I'm listing below just for completeness of the search answer. No summary and conclusions are sent for these reports. Many references in this group are basic information studies on corrosion. I found no additional information in this area which I thought would be of interest. ESR-58-18 ESR-59-4 R-55-1413 R-56-46 R-57-38 R-58-26 R-61-28 R-61-32 R-62-12 R-62-42 R-62-93 R-64-14 RM-57-5 \ -i- THIS INFORMATION FOR DU FONT USE ONLY DUP030014271 23 R.T. Khanna CRI W-75-5342 November 12, 1975 I found reference to five additional reports, but, unfortunately, we do not have microfiche copies of these reports. Possibly you may wish to check with S.G. Smith on this matter. 1339 1399 1413 R-56-26 R-57-58 help. Please feel free to call on me if you have questions or require additional Enclosures PJS/reb DU P030014272 - 24 APPENDIX II P2 AND H20 PERMEABILITY OF POLYMERS AT 25C POLYMER 02 AT 0% R.H. WATER P X 10" cc-cm/cm2 sec cm Hg P x 10" g cm/cm p-VA pVDC NYLON 6 p-CHLOROTRIFLUOROETHYLENE PET PVC pMMA pVAc p-ETHYLENE (LINEAR) CELLULOSE TRIACETATE POLYPROPYLENE POLYCARBONATE p-STYRENE p-ETHYLENE (BRANCHED) CAB p-ISOBUTYLENE p-BD p-4-METHYL PENTENE-1 p-DIMETHYLSILOXANE ^0.0001 0.012 0.062 0.18 0.42 0.48 1.0 3.3 5.4 7.2 10.8 13.5 24.9 30.0 55.8 90.0 228.0 240.0 -V3000 'vSOOO ^0.052 19.5 0.19 3.2 2.5 13.7 107 0.21 291 0.42 20.8 14.5 0.83 360 9.2 11.4 7.7 80.5 MOISTURE-CURE TAR/NCO EPOXIDIZED TAR/AMINE URETHANE (PIGMENTED) 0.53 0.85 1.1 RTK;ayk 2/3/76 DU P030014273 02 PERMEABILITY THROUGH COMMON PAINT FILMS 10~3 mg/cm2/day VEHICLE TEMPERATURE C CELLULOSE NITRATE ALKYD - MF EPOXY VINYL AIR DRY BAKED AT 60C CHLORINATED RUBBER 10 69.3 4.2 4.7 3.9 4.1 1.1 20 105.8 10.3 7.3 7.5 4.9 2.2 30 149.8 19.2 8.6 10.5 6.4 3.4 40 5 237.0 3.8 30.3 50.6 17.8 33.7 29.9 10.7 37.5 19.0 4.3 15.9 (45C) (60C) DUP030014274 26 APPENDIX IIIA PRIMER DEVELOPMENT FOR MAINTENANCE FINISHES 2 mil DPT Primer + 2 mil DPT Topcoat 369-Y-67641 Salt Spray Bating Controls; System Description * 0 Panels Hand-cleaned CRS Hrs. Corlar Primer 825-8031/VG-88339 848-E-89-1 2,1 4,S 4.5, SB Dulux Primer 67-746 848-E-93-3 1,1 4 3 RC-65851/RC-H-40981 (Clear Corlaz) 848-E-93-1R 10,10 2.5,B 3 RC-60462/H-253 (Clear Dulux) 848-E-101 * CF CF CF Inorganic Zinc 347-931 Zinc-Rich 0. Experimental Candidates 1. Epon 626/Shell Ketimine H-3 B48-E-89-2 2*1 2. Epon 826/Ketimine H-3/Keneur CP 848-E-89-3 1.5,B,2 3. Epon 826/Ketimine H~ 3/Dion 3800 848-E-89-4 1.5,1.5 4. Epon 826/Experimental Ketimine/ Dion 3800 848-E-B9-6 2,1 Epon 826/Araldite 830-850 848-E-89-8R 2.5,3 Epon 826/Araldite 830-8S0/CE 848-E-89-9 3,3 Epon 826/Araldite 830-85Q/CE 848-E-89-10 3.5,5 Epon 826/Araldite 830-850/CE Epon 1001/Ketimine 786-E-80 848-E-89-11R 5,5 848-E-100-3 2,SB,1 Epon 1001/Ketimine 848-E-97 048-E-100-6 2,SB,1 Epon 826/Verscunide 280B75 Epon 826/Emerez 1514 Epon 826/Emerez 1514/Dion 3800 Epon 826/Emerez 1514/SACI-700 Desmodur E-21 848-E-98-5 848-E-90-1R 848-E-90-2R 848-E-93-4 848-E-90-3 2,1 3,5 5.l 4,1 2,B,1 1.5 ,B 3,B 1,B 2.5,B 2 1.5 2 3 2 ,B 3 2 ,B 3 2 ,B 2.5 2,B 1,SB,2 1.5,SB '1.5,SB 1.5,SB 1.5,SB 2 1.5 2.5,8 2.5,SB 2 2.5 2.5 2 ,B 3 2,B,3 Revised 12/27/76 First Number for Clear Primer, Second Npmber for Topcoated Primer DU P030014275 PRIMER DEVELOPMENT FOR MAINTENANCE FINISHES - 27 - c c? HH 4J o-- w <o 4P-1 (8P-1, o in oco o o oo o o O 00 CO CO in o o o m (si o o o o m r- co oo t o m in m x x mvo <ov oio oo ox o o o to o o in m in P rH .VO 10 oo tr> o CN NT oo O *3* O *3" O cn H o VO o VO VoO o CO oo -3* ssr o cn o id oo o vo o P ID X 0) IIXOii o> Vm0 s 0u 1 4-1 a V4 mo a<u Vi Eo> Pe<Uy) X P to PPi a 03 i--1 O *i M n o o o Ha Vxt Q >4 8 8 94 (4 %o a 944 f rP CJ rtH8j O 0$ Bo 0* P 94 W & >O4 8 ,O8 S u NH <T co co I r-l ro o co IO t m ft H CO CN o CO r- O vo u a u & <D to in CM H U cu B rl P U 05 \ 1 C4 rH 04 t, m 03 VO <31 n3 X in O r-| P VO VO f-4 1 o> P oQ g & 0 PS 1 H rH c 0 rH N O rH 3 tr 0 C M* 8w w H E a >8 P - 8 8 8 P -P P p .<9 5 N {S P 8 8 P 8 20) i-4 O OU r*4 8 O r4. 4O1 aQ wC O <8 0O0 40 -*4 P P P p p g B 8 E O 8 e 0 8 6 pp *2 8 <8 |TaJ) -iPn s? a & d 8rl 44 r4 O a N fe* o ! 'd -8H 44 *4 O O S X X o A T) 8 -H 44 -H o O s \ XXO wa s 1? k 28 P P \ Sf a M 8 na "E *>-41 0 a \ & 0 8 O -8cCPsl <--X1 O a \X X 0 ma Ox cn OO O 8 0 8 CO c 00 cn P P cn *g ta p M u 0 D 0 r- co 0 mX 1 s U 8 8 O p X. X S 00 Cl O000 * in 1 8H 8 8 *H p $ rain in m m fcl tq X co co co co 1 1 OD p <8 c s\ 04cot5oJn e4 i4 P >8s cn t SC 8 8 cn 1 W 8 a id P 8 1 0 ro l D cn l 0 cn 9 0 cn ID CO f~ CsOy CO 0 CD CM *3* O CO XX 8* >3' 00 00 CO CO rH 1--1 fp 8 0 8 m in m 05 8 8 8 8 a rH rp rP 4-5 P P P H H p rH 0C5 -H *-H E r--f -H H E r4 P 8 H t H H E E IN M ca *3 89 d d -p H rH >--t r-l r-l p 4J 8 W O U 2p 8 p rH toO r*H 8PP jg 8 8 w t4 i4 x\X S MO NO rtf 8 8 UPP < X. W X < X ItS Vl < X S94 X rH q i X rH P O > X O B W X 8 E U X 8 X CHI 1 w ID VO -M CM 04 ID ID 00 VO ID ID 0 CM 04 cn CN CM CM CM O O 10 O 10 VO O O CM CM CM CM Jh CD CO CO co CO CO CO 00 rH rH CO CO CO CD I Vl CD c 8 8 8 co O a H O a w O a w waO -P q 8 OO O4 ww c8 0a w O Pf O Oi w 0 O o 8 0 a c 0 04 c 0 a 8 O a fi 5i (U W w w (4 a 6 w .rH 03 to in VO * *' 0 * * CO 0 3 rH rH <N rH co H 8; r-l in rH vo x \0O4' N04 iO4) CO P DU P030014276 28 cc: APPENDIX IIIB T. J- Coletti, Mar. Lab (2) R. D. Phelps, Troy Lab R. W. Laurrell, Mar. Lab P. W. Britt, Southfield M. P. Morse, Mar. Lab E. 4. Zinser, Wilmington J. P. Huff, Mar. Lab A. G. Armour, Exp. Sta. W. Pregmon, Mar. Lab J. R. Courtright, Mar. Lab R. L. Davis, Beaumont P. H. Pettit, Jr., Exp. Sta. C. A. Senkle r, Exp. Sta. File, Exp. Sta. EXPERIMENTAL STATION LABORATORY EXPOSURE NO. _________24216 DATE: March 31, 1977 TITLE: EXPERIMENTAL HIGH SOLIDS PRIMERS PURPOSE: Obtain general durability of high solids primers over hand-cleaned rusty steel and compare with Corlar and Dulux primers. MATERIAL EXPOSED: Topcoat 369-Y-67641, 2 mil DFT Primers Code* Controls 1 VO 67-746 Dulux C-CRS 825-8031/VG-88339 Corlar 347-Y-931 Ganicin EXPERIMENTAL CANDIDATES 848--E--I3t>--3A Epoxy/ Ko txinjkn 848--E-135-3B H 848--E-135-3C II II 6-2, C-CRS 6-3, SB-HRS 6-4, C-CRS, R-CRS, R-HRS 6-5, C-CRS, R-CRS, R-HRS 6 -- 6, C-CRS, R-CRS, R-HRS 848-E-137 Epoxy/Polyamide 6-7, C-CRS, R-CRS, R-HRS 848-E-138 Epxoy/Amine 6-8, C-CRS, R-CRS, R-HRS 848-E-139 Epoxy/Polyamide 6-9, C-CRS, R-CRS, R-HRS 848-E-141 848-E-93-3 848-E-89-1 848-E-142 848-E-144 848-E-143** Epoxy/Amine Dulux 67-746 Corlar 825-8031/ VG-88339 Ganicin 347-Y-931 Epoxy/Ketimine, 30% PVC Epoxy/Ketimine Al filled 6-10, C-CRS, R-CRS, R-HRS 6-11, C-CRS, R-CRS, R-HRS 6-12, C-CRS, R-CRS, R-HRS 6-13, C-CRS, R-HRS 6-14, C-CRS, R-CRS, R-HRS 6-15, C-CRS, R-CRS, R-HRS PANEL PREPARATION: Rusted hot rolled steel panels were hand cleaned by 5 strokes with wire brush at each area in One direction. All primers and topcoats were applied by air-spray to 4 mil DFT on primer and 2 mil DFT on topcoat. Primers were airdried at least overnight before topcoats were applied. All panels were air-dried at least 2 weeks before exposure. Ganicin primer over sand blast cleaned hot rolled steel was supplied by W. Pregmon, Marshall Laboratory. - over - DUP030014277 29 EXPOSURE INSTRUCTIONS: One set each of these, panels would be exposed indefinitely: 1. Beaumont, Texas, Test Racks; return after every 6 months. 2. Florida 45S; return after every 6 months. 3. Salt Spray Cabinet. REFERENCE; Notebook 878-E CHARGE CODE; 7354-211515-1400 *C-CRS - Polished clean cold rolled steel - Parker panels' R-CRS - Hand-cleaned rusted cold rolled steel, Delaware exposed R-HRS - Hand-cleaned rusted hot rolled steel, Delaware exposed **Remade as 878-E-42 and included in Exposure Series No. 24217 because of rough surface. RTK:ayk 3/31/77 R. T. KHANNA DU P030014278 "cc: T. J. Coletti, Mar. Lab (2) R. w. Laurrell, Mar. Lab M. P. Morse, Mar. Lab J. P. Huff, Mar. Lab W. Pregmon, Mar. Lab J. R. Courtright, Mar. Lab J. B. Emmons, Beaumont-TX R. D. Phelps, Troy Lab 30 P. W. Britt, Southfield E, J. Zinser, Wilmington D. Metzger, Wilmington P. H. Pettit, Jr. , Ejq>. Sta. B. V. Gregorovich, Exp. Sta. C. A. Senkler, Exp. Sta. File, Exp. Sta. EXPERIMENTAL STATION LABORATORY EXPOSURE SERIES NO. 24216 DATE: June 22, 1977 TITLE: EXPERIMENTAL HIGH SOLIDS PRIMERS - RESULTS OF 1500 HOURS SALT SPRAY CABINET PURPOSE: To obtain general durability of high solids primers over hand-cleaned rusty steel and compare with Corlar and Dulux primers. RESULTS: Dulux 67-746 on C-CRS (control, #6-1) and R-CRS and R-HRS (#6--11) shows dense blistering both in primer and topcoated section. The primer film is very weak and soft because of excessive water retention. Corlar 825-8031/VG-88339 on C-CRS (control #6-2) performs excellent but fails on rusted panels (#6-12) by dense blistering and overall rusting. Low molecular weight polyamide Emerez 1514 cured epoxy primer (848-E-139, panel #6-9) failed by dense blsitering, probably because of inadequate cure or application. All other experimental candidates on rusted panels exhibited comparable perfor mance to that of Corlar 825-8031/VG-88339 on C-CRS. Following candidates with Talc and Micaceous Iron Oxide pigmentation were judged to be slightly superior to other experimental candidates: 848-E-135-3C Epoxy/Ketimine Adduct (#6-6) 848-E-141 Epoxy/Polyamine Adduct (#6-10) 848-E-137 Epoxy/Polyamide Adduct (#6-7) These would be studied further. Ganicin 347-Y-931 continued to show excellent performance on both SB-HRS and R-HRS. Aluminum flake filled Epoxy/Ketimine Adduct primer shows excellent performance. 20% PVC appears to be adequate for primers over rusty steel. A candidate (848-E-144, panel #6-14) pigmented at 30% PVC showed adhesion loss between primer and Imron topcoat when exposed to salt spray. Experimental candidates are of low viscosity and have good wetting characteristics. This tends to saturate the rusty pores and greatly reduce water and oxygen transmission rates to the metal interface. Adhesion was judged to be excellent under both wet and dry conditions. DISPOSITION: The Salt Spray Cabinet panels have been retained by the writer. RTK:ayk DUP030014279 - 31 SALT SPRAY RESULTS SUBSTRATE: RUSTY HAND-CLEANED STEEL PANEL NO. 1000 HOURS 1500 HOURS 6-i p r ime r So f t ,# b l is t e r in g --------- ---------- ------- --------------------------> TOPCOAT BLISTERING ---------------- ----------------------------------------------- > (CR) LARGE EDGE BLISTERS 6-2 PRIMER: EXCELLENT ----- ------- -------------------------------------------- > TOPCOAT: EXCELLENT ----------------- ------------------------------ --> 6-3 6-4 6-5 6-6 6-7 6-8 PRIMER! EXCELLENT -- TOPCOAT: SPOTTY RUST * CR)* PRIMER: EXCELLENT TOPCOAT'. EXCELLENT PRIMER: t o pc o at : > * PRIMER: TOPCOAT: * PRIMER: t o pc o at : PRIMER: TOPCOAT: VP ------------------------ -------------------------------------> 6-9 6-10 6-11 PRIMER! MEDIUM BLISTERS TOPCOAT! MEDIUM BLISTERS MAXr MAX, BLISTERS BLISTERS 88 PRIMER! FYPFI I PWT -------------------- ----- ------------------------------------- ^ TOPCOATS EXCELLENT PRIMER! DENSE BLISTERS ----------------------- ------------------ -------- > (R) TOPCOAT: DENSE BLISTERS ----------------------------------------- -------- > 6-12 6-13 PRIMER: DENSE BLISTERS TOPCOATS DENSE BLISTERS BAD RUST, DENSE BLISTERS (R) BLISTERED PRIMER: EXCELLENT -------------------- --..............................................> TOPCOAT: EXCELLENT ------------ ------ i------------------------ -------------> 6-14 PRIMER: EXCELLENT ---------------- -----1---------------- ------------------------- > TOPCOAT: EXCELLENT --------- --------------------------------------> 6-15 PRIMER: EXCELLENT --------------------- ---------------- ---------------------TOPCOAT: EXCELLENT -------------------------------- -----------------------> *R REMOVED DUP030014280 - 32 - EPOXY/POYAMINE PRIMER (878-E-88) PART (A) INGREDIENTS Code Names G.W. I. H-79 Ceilosolve Acetate 8.06 II. H-35 MEK 6.66 III. KG-1105 Epon 1001 10.05 IV. RC-H-40984 In-Situ Epoxy (72% S) 8.81 V. W-109 VI. 316-MiOx Talc MiOx 22.51 39.0 VII. G-1109 Epon 826 9.7 VIII. Cardura E 8.05 TOTAL Gal. Wt. = 12.07 --> 11. 24 R.M. Cost, S/gallon = 5.45 --> 4. 65 Viscosity = 4.2-400 poise. T.I. - 95 % Solids = 70.3 (wt.), 54 .05 (volume) PART (B) INGREDIENTS Code ' Name G.W. I. H-79 II. H-35 Ceilosolve Acetate MEK 8.06 6.66 Araldite 830 9.3 Araldite 850 9.4 TOTAL Gal. Wt 8.63 Raw Material Cost, $/gallon = 8.41 PARTS Flaked Epoxy 82 22 25 In--Situ Epoxy 12.3 82.0 51.4 85.2 34.72 51.4 85.2 75.0 9.4 350.0 75.0 9.4 350.0 8 17 28 28 81 Viscosity = 20-70 cps % Solids = 69 (wt.), 62.8 (vol.) FORMULATED PRIMER Mix Ratio = 4.32 by weight, 3.1 by volume % Solids = 70 (weight) = 56 (volume) Gal. Wt. = 11.4 R.M. Cost $/gallon Coverage = 900 sq. ft./mil gallon Viscosity = 1.1-16 poise, T.I. = 15 APPLICATION CHARACTERISTICS 6.20 Pot Life = 10 hours+ Dry Time n.3_ ,hours, cure overn.ig.h_t+, Film Build/Coat * 3 mil WFT on smooth surfaces =6 mil WFT on rusty surfaces Coats/6 mil DFT * 4 SPRAY VERY WET FIRST COAT, FLASH h-1 HOUR AND RECOAT TO DESIRED DFT. DRY BULB TEMPERATURE - 76F % R.H. = 43% --___________________*.......-............. RTK:ayk (6/9/77) DUP030014281 - 33 - EPOXY/POLYAMIDE PRIMER (878-E-90) PART (A) INGREDIENTS Code Name I. H-49 Toluene II. H-12 Butanol III. Versamid 280BX75 IV. Genamid 2000 V. W-109 Talc VI. 316-MiOx MiOx TOTAL Gal. Wt. = 11.5 R.M. Cost, $/gallon * 5.00 G.W. 7.18 6.72 8.0 8.15 22.51 39.0 PARTS (Weight) 41.2 40.0 56.0 4.0 47.2 76.6 265.0 Viscos'' y = 3-64 poise. T.I. 20 % Solids = 64% wt., 44%1 vo'l. PART (B) INGREDIENTS Code Name G.W. I. G-1109 ERon 826 9.7 II. H-49 III. H-12 Toluene Butanol 7.18 6.72 TOTAL Gal. Wt. = 9.1 R.M. Cost, $/gallon = 5.90 PARTS (Weight) 100.0 11 10 121 Viscosity = 112-146 cps. T.I. = 1.3 % Solids FORMULATED PRIMER = 83% weight. 77.3% volume Mix Ratios Viscosity 2.2 by weight, 1.74 by volume 148-160 cps., T.I. = 1.1 Gal. Wt. PVC R.M. Cost, $/gallon 10.6 20% 5.35 Coverage = 900 sq. ft./gallon mil R.M. Cost C/ft.2 mil = 0.6 % Solids = 70% weight, 56% volume APPLICATION CHARACTERISTICS Pot Life = 4 hours+ Dry Time = 3 hours, overnight cure Film Build/Coat 6 mil WFT on clean smooth surfaces 8 mil WFT on rusty surfaces Coats/6 mil DFT = 2 SPRAY VERY WET FIRST COAT, FLASH Jj-1 HOUR, APPLY SECOND AND THIRD COAT TO 6 MIL DFT DRY BULB TEMPERATURE - 75F % R.H. = 54 RTKjayk (6/9/77) DUP030014282 - 34 EPOXY/KETIMINE PRIMER (878-E-85) PART (A) IKCRBDIBNTS PARTS Code Names G.W. 878-E- 85 Flaked Epoxy I. H-79 Cellosolve Acetate 8.06 232 II. H-35 MEK 6.66 132 III. KG-1105 Epon 1001 10.05 100 IV. RC-H-40984 In-Situ Epoxy (72% S) 8.81 V. W-109 Talc 22.51 192 VI. 316-MiOx MiOx 39.0 312 VII. G-1109 TOTAL Epon 826 9.7 300 1268 Gal. Wt. = 12,15, R.M. cost, $/gallon =5.25 T.I. " 100.0 Viscosity = 5-500 poise, % solids = 67% wt., 54.0% vol. PART (B) Epoxy curing agent Shell Ketimine H-3 = 184.0 parts Gal. Wt. =8.1 Viscosity =2.7 poise FORMULATED PRIMER Mix Ratios = 6.89 by weight, 4.6 by volume Viscosity = 1.9-60 poise, T.I. =31 Gal. Wt. PVC = 11.555 ! = 20% R.M. Cost $/gallon = 6,65 Coverage ft.2/mil-gal. = 972 R.M. Cost c/ft.2 mil = 0.7 % Solids (wt.) = 75 (vol.) = 60.5 Pot Life = 24 hours+ APPLICATION CHARACTERISTICS In-Situ Epoxy 232 93 139 192 312 300 1268 Dry Time ^3 hours, cure overnight Film Build/Coat = 7 mil WFT (3.5 mil DFT) Coats/6 mil DFT = 2 SPRAY VERY WET FIRST COAT, FLASH h~l HOUR, APPLY SECOND COAT TO 6 MIL DFT DRY BULB Temperature = 74F % R.H. =50 RTKrayk 6/9/77 DUP030014283 35 EPOXY PRIMERS For Hand-Cleaned Rusty Steel Epoxy/ Ketimine Epoxy/ Polyamine Epoxy/ Polyamide Awlgrip 85A % Solids (wt.) (vol.) Pot Life, Hours PVC R.M. Cost, $/gallon Wet Dry 75 60.5 24+ 20 6.65 11.00 70 56 10+ 20 6.20 11.10 70 56 4+ 20 5.35 9.55 54.4 40.3 OC 19.4 5.17 12.83 Gal. Wt., lbs./gallon 11.555 11.4 10.6 9.16 Dry Time, Hours 3 3 33 Wet Film Build 7 6 84 Coats/6 Mil Dry 2 2 23 Package 22 21 Unknowns/Problems Cure Toxicity latitude of Penetration r_e_s, id ual amine Penetration Penetration Toxicity Film build DUP030014284 e P o B> rH o0 o3 >4 a ij Q 03 \W- rH 0 1 H S, >4 <4 QM P pH -O- OO Oo rH rrH oo o o m 36 - o in o rH in rH in O O infH o n rH CM o n ONH H rH CM ; in rH o CO oo ro CM CM rH CO a\ r-V VO 1 CO * CO* tn CO o o o CN O o o rH O ZIN C -FR EE MAINTENANCE PRIMERS 45 55 Esis 3 in 13 rH 'H O rH >o cn Wo C92 . <d a > VO* * o in l> orooO rH vo NT in in o in vo' o VO VO m VO in vo in i--i oCM f> *H rH COa rrH o *** vp in vo in ro* CoMt T1 00 O 00 CO CO vo in vo rH rH rH CM OOa rrH 0 in raOH ^iO3!' rH -H m <u U5 CO ON CM H CO rH rH in in CO CO 00 m in * 00 vo* VO in rH rH o rH rH rH ON r- 00 op vo vo CM rH 00 ON \rH o0C0O vo in1 icHo 1 CM ON l 00 o r^* ID riHn i u cc 10 1 O iH rH q u rH P o 3 fl a Q o u rH n) p c 0) EH in 0) a X w >Xi X>i X>i oo o WQ< WO. WOj rd d 0) H<DI rH H H EH c9 *<du H H fHO oX i--t H He m * i i<n 00 *cHu M rH <! (0 4J w o a c 0H to U 01 > e o o CO J3 -TA3 O' rH XA! W <pu (D o z SH CaO. 'd +* 0) 0 <u X3 (3 a) Og rH rH H o o<U *2 *03 * r- \in rH Nvo M rO >i id <CDO H > 0fc$H 0) p$ DUP030014285 cc: APPENDIX IIIC - 37 T. J. Coletti, Mar. Lab (2) R. W. Laurrell, Mar. Lab M. P. Morse, Mar. Lab J. P. Huff, Mar. Lab'' W. Pregmon, Mar. Lab J. R. Cour-bright, Mar. Lab R. L. Davis, Beaumont Ri D. Phelps, Troy Lab P. W. Britt, Southfield E. J. Zinser, Wilmington A. G. Armour, Exp. Sta. P- H. Pettit, Jr., Exp. Sta. C. A. Senkler, Exp. Sta. File, Exp. Sta. EXPERIMENTAL STATION LABORATORY EXPOSURE NO. _________24217 DATE: March 31, 1977 TITLE: EXPERIMENTAL PRIMERS FOR RUSTY STEEL PURPOSE: Obtain general durability of high solids primers over hand-cleaned rusty steel and compare with Ganicin IOZ primer. MATERIAL EXPOSED : Topcoat 369- Y-6764I, 2,mil DFT Primer 848-E-147-A Epoxy/Ketimine Zn-Flake Code * 7-1, C-CRS, R-HRS 848-E-147-B N II Ser-X 7-2, C-CRS, R-HRS 848-E-147-C Cl M W-88 7-3, C-CRS, R-HRS 848-E-147-D n ii Glass Flake 7-4, C-CRS, R-HRS 848-E-147-E it ti Zn-Flake 7-5, C-CRS, R-HRS 878-E-38-1 878-E-38-2 848-E-147-F 878-E-42 Control 347-Y-931 Hybrid with W- 198 Hybrid with Zn -Flake Epoxy/Ke timine W-198 Epo xy/Ke timine W-128 7-6, C-CRS, R-HRS 7-7, C-CRS, R-HRS 7-8, C-CRS, R-HRS 7-9, C-CRS, R-HRS 7-10 , SB-HRS PANEL PREPARATION: Rusted hot rolled steel panels were hand cleaned by 5 strokes with wire brush at each area in one direction. All primers and topcoats were applied by air-spray to 4 mil DFT on printer and 2 mil DFT on topcoat, primers were airdried at least overnight before topcoats were applied. All panels were air-dried at least 2 weeks before exposure. Ganicin primer over sand blast cleaned hot rolled steel (control) was supplied by W. Pregmon, Marshall Laboratory. EXPOSURE INSTRUCTIONS: One set each of these panels would be exposed indefinitely: - over - DUP030014286 38 1. Beaumont, Texas, Test Racks; return after every 6 months. 2. Salt Spray Cabinet. 3. Florida 45S Test Racks; return after every 6 months. REFERENCE; Notebook 878-E CHARGE CODE; 7354-211515-1400* * i --....... -..f......................... ............. *C-CRS - Polished clean cold rolled steel - Parker panels R-CRS - Hand-cleaned rusted cold rolled steel, Delaware exposed R-HRS - Hand-cleaned rusted hot roiled steel, Delaware exposed RTK;ayk 3/31/77 R. T. KHANNA --J3- DUP030014287 39 FLAKE PIGMENTS Zinc Flake 21 HF (at 88% wt. solids) Ser-X Talc platelets Wet Ground Mica (W-88) Glass Flake (1/64" Hammered Flake) Aluminum Flake (W-128) DUP030014288 COST ESTIMATES 40 o X & + fa o- c 4J ro-f m 8o ]j OS <"N .-I t o r~ c* IN 04 oo n vp *9 a\ o\ >o (0 a> N CD 4 SO OS 1A- in C -Pi r41+| SSI n H " 04 o r- in in in r*i *-* in n N r4 !,, u ^ fa r-t o< t t u eag sto <J) W X< 0 CD 4 -+ 40 fa CD 1 c . fi N O C s 0! ** 0 3 3 I p'v m X rj 0> e X '> DUP030014289 41 cc: APPENDIX HID T. J. Coletti, Mar. Lab <2) R. W. Laurrell, Mar. Lab M. P. Morse, Mar. Lab J. P. Huff, Mar. Lab W. Pregmon, Mar. Lab J. R. Courtright, Mar. Lab J. B. Emmons, Beaumont J. M. Donatello, Exp. Sta. File, Exp. Sta. R. D. Phelps, Troy Lab P. W. Britt, Southfield , E. J. Zinser, Wilmington D. W. Metzger , Wynnewood A. G. Armour, Mechelen P. H. Pettit, Jr., Exp. Sta. B. V. Gregorovich, Exp. Sta. C. A. Senkler , Exp. Sta. EXPERIMENTAL STATION LABORATORY EXPOSURE NO . 24323 DATE; October 7, 1977 TITLE; Experimental High Solids Primers PURPOSE; Obtain general durability of high solids primers over hand-cleaned rusty steel and compare with controls. MATERIAL EXPOSED; Topcoat 369-Y-67641, 2 mil DPT Controls (see attached) PANEL PREPARATION; Rusted hot rolled steel panels were hand-cleaned by five strokes with wire brush at each area in one direction. Primers were air-dried at least overnight before topcoats were applied. All panels were air-dried at least two weeks before exposure. Ganicin primer over sandblast cleaned hot rolled steel and hand-cleaned rusty hot rolled steel was supplied by W. Pregmon, Marshall Laboratory. EXPOSURE INSTRUCTIONS: One set each of these panels would be exposed indefinitely: 1. Beaumont, Texas, Test Racks; return after every 6 months. 2. Chambers Work 3. Salt spray cabinet at Experimental' Station REFERENCE; Notebook 878-E CHARGE CODE; 7354-211515-1400 RTK:adw Attach. DUP030014290 in ^ n> m s Q) xg g U-H n H ft M >--1 H X! ft* ft ft B -- g in (<i 'O'^ N N N'"f 42 xj* n vo vo in vo iiii <n m n* ft (nn,n'irin'9,in<n 3 4 5 6 7 10/7/77 s fot 44 10 'O'O'O'O'O'O'O'O o ID<DCDID<D<U<D(D 'fHt EM iM-S si >1 >i EM Em njiocoina)n}(d(0 ft MM33MMMM ft ft ft MM ft ft ft ft tn w aun co to tn k '0*0 o 'O'O'O'O'O'O'O'O'O'O'O'O <0 CL) CD (DIDIDIDGltDCDIDCDtDIDCD s: si in m 1 m Em Em EM X! X X <0 (0 (0 <0 10 M id to to to to 33 3 M M M M M 3 M M3 333 M M mm M ft ft ft ft ft M ft ft M M M M cococococopQcocoixiXfQcQ *0 c < <a ID 44 s fot 44 ft M M 10 M P tn X 3 CO o 0} Lr/C-I\D4I cn 41= ft O cn M 0) 44 ft 3M 0 CD o CO CO (X ex I CQ CO co co CO IX M IX (X EX EX EX 1 f1t0 1 1 CO o M a (X X O CO EX EX co co co O 1 fX an ei CJ X EX SScv 3 3 X 3 1 I I CO f4 H rH O o m cn w w *3/ ^ U4 M VJ w H *H X Cl 00 C G 3 rf O CD ft) r-l LTj > e> o 3 co CO Qo \ft ft ft ft ft ft in oo VO 4* ft o CM CM 41 t M 03 1 1 ft EX tn 1 ft 41 ft *4* f1t f1t *&r! ft 04 ro n vo vo < CO *-t CM CO lliiiit1 co CM CO CM tn a) 44) to u H TJ 3 3 O ft (0 44 a ID .g M M 0) ft X IX EI1d o EX CO CO M CO a) I I (X g CO CO O U CO EX rl Si KWK CO 1 O M ft s t ex ex co CO o EX m CO fot o tx ex I (X cn S3 -O Pi -p o I -H EX 3 (0 EX 1 O 44 3 EX 0 Uft 3 N O tn EX -P 10 g2 IX r) 44 3 -P cn 3 ID (0 3 ft *o O 3 H rl P -P o o fIDt ft a) 4J g ft M i0 3 ft > O N CD 4-1 fCMt *o id tr> 4- ft 3 ft ID P 10 fUt cn 0 a g *0+ &4J t*> ft So 2 0) o ft ID r- co g co co CO ; CD Pi pi pi IX VAC a^-tasn EX ft Id x f>t1 XJ 4- AJ 4-1 i" *H -H r- ft <d i_ <d i i I fti--1 floidUHou IX CM ID EX (1) EX O EX EX CQ 00 5! & ft ft 3 00 CO SX oo > ft EX ft -M W I <H j X l" O ft 3 o 3 r~- ft if*t- r- + (D ft ID -h o -h n1 a> n< I ft ft 3I M tJ EX TJ ft j> m O Oo o S N tS3 IS Is 3 g g cn m tn vw ^ U 'T ^ /N I 1 cap dp trj #> tc o 1 O I | in ft ft ft ft ft VO --r VO "-r VO irf rtj @ rt! @ <U CD = 0) 33 3 ft ft M g g . g= ft ft -H 4J 44 +1 CD CD ID AC \\ S ID 3 CD 3 to >o A! ft +1 rl H RS fgt fgt (0 3 tC CO EM +1 44 0) M M ID CD AC A! ft>QJ O <0 S xa xa x 3B 3B 3 Ai ft Cw ft Cl , ft a 32 3S 3 Em >i Em Em*G X X X! XJIXEOi oo ftft Oft O O O OM ft ft ft ftft B Q B Q E4 Q w w IX m tx w w < CTk O H r-i H ojro'sj'tnvor^ooovoftcMin ft ft ft ft ft ft ft ft 04 04 04 C4 I rO | IIIIIIIIIIII CM ro CM 'O (*0 DUP030014291 43 APPENDIX IV CORROSION CONTROL,BY INHIBITORS IN COATINGS V, DUP030014292 44 PRIMER FOR RUSTY STEEL LITERATURE SURVEY CORROSION MECHANISM AND ITS PREVENTION o ROLE OF INHIBITORS IN CORROSION CONTROL USE OF INHIBITORS AND LEADS FOR THEIR USE IN PRIMER SYSTEMS CONCLUSIONS* ORGANIC VEHICLES ALONE PROVIDE LIMITED PROTECTION HIGH PERMEATION OF 02, WATER, AND IONS IN ALL ORGANIC FILMS BECAUSE OF MOLECULAR INTERACTIONS, SOLUBILITY, AND VOIDS EXCESSIVE WATER IS ALWAYS PRESENT AT THE INTERFACE AND ` WATER CAUSES ADHESION LOSS AS A PREREQUISITE FOR THE START OF CORROSION PROCESS OXYGEN PERMEATION IS THE SLOWEST PROCESS AND CONTROLS THE CORROSION RATE ' ELECTROLYTIC CELLS ARE BUILT-IN STEEL 0 BEST PRIMER VEHICLES (LOW PERMEABILITY) ARE THOSE BASED ON AROMATIC/INORGANIC OR HYBRID SYSTEMS SUPPLEMENT WITH INHIBITORS, EVEN POORER VEHICLES MAY PROVIDE ADEQUATE PROTECTION MAINTAIN NEUTRAL/ALKALINE ENVIRONMENT AT INTERFACE DU P030014293 45 ALTERNATIVES FOR PRIMER DEVELOPMENT PROVIDE IN--SITU CURE PENETRANT PROVIDE CORROSION IMMUNITY BY INHIBITORS BUILD-IN LEACHABLE PASSIVATING IONS IN THE COATING AS A CONTROL OF THE ENVIRONMENT AT THE INTERFACE PROVIDE VERY HYDROPHOBIC PRIMER WITH OPTIMUM WET ADHESION -* MAINTAIN ADHESION AND UTILIZE INTERFACE WATER TO PLASTICIZE VEHICLE; A NON-INTERACTING POLYMER WOULD LOSE ADHESION BUILD-IN HIGH BUFFERING CAPACITY TO RETAIN ALKALINITY PROVIDE PRIMER WITH LOWEST PERMEABILITY PROPERTIES, ESPECIALLY Oz PERMEABILITY MAINTAIN BASIC MEDIA AT THE INTERFACE 0 PROVIDE COMPLEXES THAT RESULT IN INSOLUBLE, IMPERMEABLE IRON COMPOUNDS; PHOSPHATES, BORATES INCREASE TORTUOSITY WITH "TREATED FILLER" OF MAXIMUM PLATELET CONFIGURATION, MICA, Zn, Al PROVIDE SACRIFICIAL PROTECTION BY ELECTROCHEMICAL MEANS, Zn, Al, Mg, SALTS/DUST 0 USE MULTI- VALENT COMPOUNDS TO FORM INORGANIC POLYMERS WITH Ca, Ba, Zn, SULFONATES, FORMATES, OXALATES, PROPIONATES, PALMITATES, SEBACATES, AND AZEALATES INHIBITING PIGMENTS/INHIBITORS ADDED EXTERNALLY HIGH ELECTRICAL RESISTIVITY VEHICLE DUP030014294 46 NODES OF CORROSION CONTROL A. PHYSICAL BARRIER (PERMEABILITY) - VEHICLE (ORGANIC VERSUS INORGANIC) - FILLER (PARTICLE SIZE, PLATELETS) - THICKNESS (MICRONS TO MILLIMETERS) B. CHEMICAL BARRIER (PASSIVATION, INHIBITION) ~ CHROMATES - BUFFERS - ADSORBING AMINES, ETC. C. ELECTROCHEMICAL BARRIER (SACRIFICIAL Zn, Mg) D. ELECTRICAL BARRIER (CATHODIC PROTECTION) EXAMPLES: 1. ORGANIC PAINTS (A + B) .2 INORGANIC ZINC (A + C) 3. DRILLING FLUID, PROCESS WATER (B + OXYGEN SCAVENGERS) 4. METAL PRETREATMENT (INORGANIC COATINGS) DUP030014295 47 CRITERIA FOR' CORROSION INHIBITORS VERY SLIGHT SOLUBILITY IN WATER - Enough to maintain and replenish inhibitor at the interface INSOLUBLE PRODUCTS OF REACTION with iron, vehicle, or water ABILITY TO FORM COMPLEXES - Inorganic polymeric films of very low permeability (high crystallinity) HIGH BUFFERING CAPACITY - Enough to maintain near neutral or alkaline (pH >7) at all times Under acidic exposures for the text interval, 10.00-2000 hours/salt spray e Multiple reactant yielding by-products which are more effective inhibitors Isocyanates Amines + Carbamates DUP030014296 48 LIST OF POTENTIAL CORROSION INHIBITORS 1. Zn, Ba salts of nitro/amino/phenolic-ACIDS .2 Zn, Ba complex of polyamines and boric acid 3. Aromatic amine salts of nitrites, stearates, azealates, benzoates, phosphates 4. Ba stearates, benzoates, fluoride, feldspar (A1FS), fluorospar (CaF2), Ba fluorosilicate, Zn acetylacetonate 5. .(CH2) nCooBa (CHj)nCooBa .6 a. 2,4 Dinitro, O-nitro-aniline b. p-Amino diethyl aniline 7. Di-phenyl amine .8 Di-phenyl acetonitrile O-nitro-derivatives 9. N,N'-diphenylurea (carbanilide) .10 N,N*-diphenyl guanadine .11 N,N"-diphenyl benzoguanamine .12 Substituted propyl amine (Jefferson), piperazine 13. N,N*-diethylcyclohexylamine 14. N,N*-cyclohexylamine carbamate 15. Substituted Dicy, melamine 16. p-Nitro,-O-amino phenols 17. O-nitro benzonitriles 18. Amino pyridines 19. p-Amino benzene sulfonamides .20 O-Toluidine O-Anisidine O-Phenetidine MPDA MDA derivative Amino-benzoic acids Amino-phenols DUP030014297 49 21. Sodium hexametaphscphate (MPPG) glass containing Ba( Zn, Ca, Mg, Al oxides, phosphates, promoting ''scale formation" such as FeCa (P03) S8II20 22. Fatty acid derivatives R % CiaH37 a) 1, 2, 3 amine b) Diamine _\ a . . e c) Amides D (CH2CH2O) H R Nv(CH2CH20)yH d) Salts of above with oleic, dimer, naphthenic, phosphonic, benzoic acids e) Amphoterics CH3-CH-CH2COOH R-NH f) Morpholines, imidazolines, derivatives, and salts .N. R-C N CH2 c h2 I c 2h ,, 23. 1,2-Hydroxyethyl-l-benzyl-2-tridecyl-2-iinidozolium nitrite, benzoate, azelate 24. Pyridine monocarboxylic, picolinic, 180"-nicotinic acids and their basic salts 25. Benzotriazole 2.4.6-collidine (0.1M optimum concentration) 2.6-lutidine 0.1M pyridine 0.15M 26. NOz $ NH2*H3B03*Ba0 3[N02 $ NH2]H3B03 K02 $ NH2 *H3B03 * ZnO N02 4) NH2 COOH-CH2 ) 7CooBa NOz t)> NH2 *OPA*-|-BaO(or -|-ZnO) 27. Polymeric a) {Epon 826)*H3P04`BaO(ZnO) -Fatty amine (Aromatic amine/DETA/TETA)*H3P04'(H3B03) b) (Sty/MAn)-Zn, Ba Salt c) (Polyamic acids) Zn Ba salts d) P (fc'JMA/MAA) copolymers, complex polyamines BaO, ZnO e) p (MA) --hydroxyl amine NH-OH (hydroxyamic acid) DUP030014298 50 - 28. Above materials prepared as encapsulated pigment 29. Compounds that form stable coordination complex with iron, zinc. Mg, Al, Ba 3 o h <t C _ N _^0H Hydroquinone bischelate Ferrocene -.cyclopentadiene complexes 30. Boron nitrite 31. Mercaptobenzotriazole Na, Ba, Zn salts 32. Quaternaries Ri CH; + A Ra CH; 33. Fluoro-alumino-silicate glasses Ion-leachable glasses Fluorobonic acids Quartz + Al203 + Flux of Na, Ca, AlF3 A1{P04)2 at 1050-1350C for 40-150 minutes Ba borosilicate, Ba metaborates Zn hexafluorosilicate, Zn borate 34. 2,4-Dinitrophenol-MDI/TDI. Polyamino-acid. (ZnO/BaO) RTKtayk 10/28/76 DUP030014299 51 CR & D DEPARTMENT HELP REQUESTED IN THE FOLLOWING AREAS: 1. SELECTION/DESIGN - SYNTHESIS OF INHIBITORS - AMINES OF ADEQUATE SOLUBILITY/EFFECTIVENESS BALANCE - COMPLEXING AGENTS CAPABLE OF FORMING INSOLUBLE INORGANIC SCALE AT THE INTERFACE - ZINC, CALCIUM COMPOUNDS; ORGANOMETALLIC COMPLEXES THAT MAY PARTICIPATE IN CORROSION PROCESS 2. INORGANIC COATINGS - AIR DRY - INSOLUBLE - BOND TO IRON/RUST SILICATE; TITANATE; BORATES; AND OTHER METAL OXIDES 3. CORROSION SCIENCE AND CHEMICAL MEANS OF CORROSION CONTROL - PRIMARY INTEREST IN SALT-WATER INDUCED CORROSION DUP030014300 52 CORROSION AND INHIBITORS SELECTED PUBLICATIONS 1. CORROSION./ VOL. X & II, SHRIER 2. CORROSION INHIBITORS, NACE 3. CORROSION INHIBITORS, BREGMAN 4. CORROSION INHIBITORS, MANUFACTURE, AND TECHNOLOGY (NOYES DATA) RANNEY 5. CORROSION AND CORROSION CONTROL, UNLIG 6. BETZ HANDBOOK OF INDUSTRIAL WATER CONDITIONING 7. EUROPEAN SYMPOSIUM ON CORROSION INHIBITORS DUP030014301 53 LIST OF COMMERCIALLY AVAILABLE CORROSION INHIBITING NON-CHROMATE PIGMENTS AND INHIBITORS Name Zinc Oxide (W-8) Zinc Phosphate '317' Zinc Molybdate (molywhite 101) (molywhite 212) Zinc Phosphooxide (Nalzin SC-1) Zinc Flake 21 HF Barium Metaborate {Busan 11 Ml) (W-178) Halox CW-2230 (Caclium Borosilicate) CW-22, CW-221 Halox CW-11, CW-111 (Calcium Phosphosilicate) Zinc dibenzyldithiocarbamate (Arazate) Zinc Salt of Nitroisophthalic acid (Sicorin RZ) Aluminum Flake (W-128) Lithium Benzoate DUP030014302 54 CHROMATE AND LEAD-FREE ANTl::CQRKQSION PIGMENTS As a result of recent legislative activity and the present atmosphere regarding use of "chromate" and "lead" containing pigments/many chemists in our technical organization are attempting to formulate anti-corrosion products with replacements for the tried and proven "red lead" and "zinc chromate" pigments. This "C" addition to the monthly New Materials Report Will be temporary in nature (4-6 months), but will attempt to provide the following information: a. A listing of the various lead and chromate free pigments which are being offered or have been used in anti-corrosion products. b. Identification of Chemists in the various laboratories who have received samples. This will permit chemists to obtain background on results of previous experiments (if any were actually carried out), and may help prevent duplication of effort or waste of time if previous results were unpromising. The Pigments listed below are those known (by the writer) at this time as being offered for this end use. If anyone knows of other pigments which should be added to the list, please drop a note to O. R. Volk, Marshall Laboratory, for inclusion in subsequent listings. 1. Moly-White 101 - Zinc Molybdate compound manufactured by Sherwin-Williams Co. for use in solvent systems. Samples received by: O. R. Volk, Mar. Lab. E. J. Donnelly, Mar. Lab. John Murray, Chicago Plant 2, Moly-White 212 - Calcium Zinc Molybdate compound manufactured by Sherwin-Williams Co. for use in water dispersible and latex systems. Samples received by: G. Goodell, Troy O. R. Volk, Mar. Lab. T. Smearing, Troy DUP030014303 3. Zinc Phosphate is available from Reichard-Coulston, Inc. as "317" Zinc Phosphate and from Mineral Pigments Corp. as "0852" Zinc Phosphate. Samples received by: G. Goodell, Troy J. A. Vasta, Mar. Lab. M. M. Willey, Mar. Lab. O. R. Volk, Mar. Lab. 4. "316" Micaceous Iron Oxide is available from Reichard-Coulston, Inc. Samples received by: E. J. Donnelly, Mar. Lab. O. R. Volk, Miar. Lab. 5. Halox CW-11 is a calcium phospho silicate composite pigment available from Halox Pigs., a Division of Hammond Lead Prod., Inc. for use in water and oil systems. Samples received by: E. J. Donnelly, Mar._Lab. O. R. Volk, Mar. Lab. E. R. Werner, Mar. Lab. 6. Halox CW-111 is a fine particle size grade of CW-11. Samples received by: E. J. Donnelly, Mar. Lab. 7. Halox CW-22 is a calcium boro silicate composite pigment available from Halox Pigs., a Division of Hammond Lead Prod., Inc. for use in wafer and oil systems. Samples received by: O. R. Volk, Mar. Lab. E. J. Donnelly, Mar. Lab. E. R. Werner, Mar. Lab. J. Jeffery, Flint 8. Halox CW-221 is a fine particle size grade of CW-22. Samples received by: O. R. Volk, Mar. Lab. E. R. Werner, Mar. Lab. 9. Halox CW-2230 is a calcium boro silicate composite pigment with a higher Boron content than CW-22. Samples received by: O. R. Volk, Mar. Lab. John Murray, Chicago Plant 10. Busan 11-M-l silica modified barium metaborate pigment, is availabl e from Buckman Laboratories, Inc., and can be used in water and oil systems. Samples received by: Available for many years as Raw Material Code W-178. John Murray, Chicago Plant 11. Zinc Oxide (W-41). Samples evaluated by: John Murray, Chicago Plant DUP030014304 56 12. Sicorin RZ is a zinc salt of an organic nitrogen compound for use in solvent and water based primers. Samples received by: John Murray, Chicago Plant T. J. Smearing, Troy Lab. 13. The April, 1976 issue of journal of Coatings Technology contained a report from the New England Society for Coatings Technology Technical Committee comparing various Corrosion Inhibiting Pigments Used in Latex Coatings on Steel. 14. Paper No. 132, presented at the International Corrosion Forum in Houston, Texas, Mar. 22-26, 1976 described Rust Inhibitive Primers Utilizing Pigments Other Than Lead and Chromates. 15. Ferrophos Pigment is Fe2P and is used in zinc rich coatings as a replacement for Zn metal. It provides improvements in weldability, gas torch cutting efficiency, intercoat adhesion and economics. Samples received by: M* M. Willey, Mar. Lab. J. R. Courtrighf, Mar. Lab. Poiidura has found Molywhite 101 to work well in oil/solvent systems but that Molywhite 212 and Sicorin RZ did not perform satisfactorily in water based systems. If other researchers would like to share their results (reports) on work with the above anti corrosion materials, please contact Chris Peters, Room 6-1244, Brandywine Bldg., Wilm. ORV:]p 7/15/76 DU P030014305 HJII Industrial I\Itan Chemicals NL Industries, Inc., Industrial Chemicals Division P.O. Box700Hightstawn. N.J.08520609/448-3200 57 NALZIN SC-1 CORROSION INHIBJTIVE PIGMENT DS -139 DESCRIPTION NALZIN SC-1, a zinc phospho oxide complex, is a versatile lead free corrosion inhibiting pigment equally suitable for both aqueous & solvent based protective coatings. TYPICAL PROPERTIES Composition............................................................. ........................ Zinc phospho oxide complex Form .......................................................... ............ ........................ Finely divided powder Color ....................................................................................... White Density(gm/cm3) ....................................... ............................... .... 4.06 (Ib/U.S. gal) ..................... ................................................33.8 Bulking Value (U.S. gal/lb) ............... ;............................................. 0.0296 Oil Absorption (gms/100 gms) ...................... ............................. .. 50 - 70 Bulk Density (gm/cm3) .......................................... ................. ...... 2-3 Solubility (in H*0) ...................... ................................................... 0.1% max ADVANTAGES Stable in a wide variety of binder systems Highly efficient corrosion inhibiting action Suitable for virtually ail types of coating systems White color allows formulating of virtually any color coating Minimizes tendency for flash rusting in aqueous coatings Excellent throwing power and can stability in electrodeposition coatings Excellent cost effectiveness WHERE TO USE NALZIN SC-1 INDUSTRIAL and TRADE SALES anti-corrosive coatings -- over -- NOTE: The recommendations made herein are based on our . research and the research of others, and are believed to be accurate. No guaran tee of their accuracy is made, however, and the products discussed are sold without warranty, express or implied, and upon condition that pur chasers shall make their own tests to determine the suitability ot such products for their particular purposes. Likewise, statements concerning the possible use of these products are not intended as recommenda tions to use these products in infringement of any patent. DU P030014306 - 58 HOW TO USE NAL2IN SC-1 SOLVENT BASED COATINGS: Other than following proper formulating techniques, no special precautions need be taken. We suggest anywhere from % to 1 V4 lb NALZIN SC-1 per gallon. Studies indicate that in many cases loading in the V* to 1 lb range PERFORM as well as a 1% Ib/gallon loading. Due to the relatively high oil absorption of NALZIN SC-1, it is suggested that loadings not exceed 2 ib/gal. Also, formula PVC should generally fall below 40%. WATER BASED COATINGS: Water Reducible: Same as solvent based coatings. Latex Systems: NALZIN SC-1 works extremely well in all types of latex systems. For optimum performance we recommend: 1. Use % to 1 lb NALZIN SC-1 per gallon of coating. 2. Keep the pH of the coating within the desirable range for the polymer type: PVA's, vinyf/acryljcs styrene/acrylics......................................pH: 8.5-9.5 vinyi/ethylenes acrylics ................................................. pH: 9.0-10.0 3. Use sufficient dispersant and wetting agent to insure a stable system. -- Dispersants found to work well with NALZIN SC-1 include Rohm & Haas' "Tamol 850" as well as KTPP. -- We suggest about 1% dispersant (active) based on the total weight of the pigmentation as a start. -- Frequently a split dispersant addition (about y* in the grind, and V* in the letdown) works quite well. 4. Keep the PVC of the coating at 30% or less (due to the less than 100% binding efficiency of latices, the formula PVC must be kept well below the pigmentation CPVC to insure good film integrity). Studies indicate that NALZIN SC-1 frequently performs as well at the % tb/gal level as at the 11b/gal level in latex systems. The pH of the latex coating should be kept in the proper range fortwo reasons--one: dispersants are most effective at moderately high pH's and two: moderately high pH's are more conducive to freedom from corrosion (particularly flash rusting) while the latex coating is still wet. DUP030014307 59 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. 21. 22. 23. 24. 25. 26. 27. 28. 29. 30. 31. 32. LIST OF POTENTIAL INHIBITORS (Suggested by Various Suppliers) Additive Tv Zelec UN Zelec NK Zelec UT MPD-4577 MPD-4547 MPD-4548 MPD-4546 c8-12 Phosphate C8_12 DEA Salt 016-18 Phosphate Trithione Titanate OH-Titanate Phosphate Ken-React TTOP-38 Ken-React TTS Ken-React TTOP-12 Phosphate Titanate Phosphate Ken-React TTOPI-41B Ken-React GTDOP-138 Ken-React GTDOP-112S Ken-React TTBS-9S Phosphite Chelate Phosphate Chelate Phosphate Sulfonate Ken-React TTBPP-58S Armeen 2C Armeen C Armeen O Duomeen T Duomeen TDO DMAMP-80/Paraolyn 300 DMP-30/Pamolyn 300 None Control MPD-4549 MPD-4629 MPD-4630 MPD-4631 MPD-4632 Pamolyn 300 Hydroxy-Titanate Titanate OH-Titanate Titanate OH-Titanate WX-109 A-187 DDBSA-OA Pamolyn 220-Epoxy Epoxy-Silane Amine-Salt DUP030014308 60 LIST OF POTENTIAL INHIBITORS (Continued) 33. 34. 35. 36. 37. 38. 39. 40. 41. 42. 43. 44. 45. 46. 47. 48. DDBSA-OA 5% Solution SACI-700 Ac tan Tectyl 506 Dicyclohexylamine ammonium nitrate F-786 Phenyl-Thio Urea 8-Hydroxy-Quinoline Anthranilic acid 3,5-diaminobenzoic acid p-nitroaniline Surfynol 104 2 EMI Quinoline m-Aminopheno1 Nicotinic Acid 49. 50. 51. 52. 53. 54. Hexamethyleneimine Lithium Benzoate, Cinnamate, Salicylate Zinc dihenzyl thiocarbaraate Zinc imino diacetate n-Butyl Stannoic Acid n-Phenyl cyclohexylamine Amine Salt Ca Sulfonate of Petroleum Polyphenol Chelate Epoxy-Silane Acetylenic glycol COOH DUP030014309 61 CORROSION CONTROL AND INHIBITOR TECHNOLOGY EVALUATE COMMERCIAL INHIBITORS IN ALKYD AND EPOXY VEHICLES EVALUATE PROTOTYPE INHIBITORS AND ESTABLISH TEST METHOD FOR INHIBITOR SCREENING ESTABLISH SELECTION CRITERIA FOR CORROSION INHIBITORS IDENTIFY MODE OF APPLICATION OF INHIBITORS DEVELOP HIGH ACTIVITY INHIBITORS AND ASSESS THEIR USEFULNESS IN FINISHES IDENTIFY OTHER POTENTIALLY FEASIBLE APPLICATIONS OF INHIBITORS; METAL TREATMENT* WASHCOATS* ETC. DUP03001431 0 - 62 APPENDIX V QUICK-SET CUKE PENETRANT PRIMER RESULTS 1500+ HOURS SALT SPRAY OF HYPALON BASED IN-SITU CURE PRIMER Penetrant III Accelerator 808/BMA/XD-9002//10/60/30 and Penetrant V Accelerator 808/XD-9002//10/90 at 20% solids in xylene, H-79, or MIBK are preferred candidates W-128 aluminum based primer performs extremely well over R-HRS Aluminum powder filled primers are too permeable and fail by spot rusting Performance on C-CRS (Q-panel polished) was consistently inferior in the entire series Recommendations: 1. Assess toxicity of Accelerator 808 2. Determine if low solids system is a viable candidate 3. Confirm safety aspects of handling aluminum flake with Hypalon 4. Consider alternate low/no toxicity systems RTK:ayk 6/17/77 DUP030014311 E. i. DU PONT DE NEMOURS AND COMPANY Fabrics and Fintshes Department FFD NO.:___________________________ Date: 4/12/77 TO: J- E. GRIFFITHS, LEGAL, WILMINGTON FROM: R. T. KHANNA, F & F, EXPERIMENTAL STATION REQUEST TO FILE A PATENT APPLICATION Descriptive Title: FINISHES FOR BUSTY STEEL AND OTHER MARGINALLY CLEAN SURFACES Summary of Invention: A coating system characterized by the following: (a) Penetrant and/or good surface wetting agents capable of undergoing in-situ cure to~a coherent film when coated with a suitable topcoat. The penetrant can be a single component or a blend of reactive couponents. it is of low viscosity and possesses good penetration and surface wetting properties. Viscosity can be further reduced by dilution with a medium volatility solvent. (b) A primer containing a reactive species [as a part of the backbone or an external additive(s)I which on contact with the chemical species of the penetrants initiates cure of the underlying film and provides interfacial grafting and/or crosslinking with the constituents of the penetrants: preferably it is pigmented. (CONTINUED ON ATTACHED PAGE) Publications: This is an extension of Du Pont's effort in "Quick-Set Acrylic Adhesives" (Cavalon) with the difference that, for the purpose of present application, Hypalon 30 is dissolved in a hydrocarbon solvent instead of a reactive monomer (MMA, BMA, etc.). The use of monomer to dissolve is not excluded but is restricted here to eliminate (a) toxicity, (b) volatility and odor, and (c) air-inhibition of the cure at the air-polymer inter face. Monomers and/or additives that overcome these problems can be used in the practice of this coating system. Detailed references can be obtained from our Cavalon acrylic adhesive program. Importance of Invention: Coating rusty steel without elaborate cleaning such as sand blasting, abrasive grinding, polishing, and/or careful metal treatments (chromate or phosphate) has been an unattainable goal for a long time. This is an initial effort to identify systems that would provide extended service life under corrosive atmosphere. It is an alternative to sand blasting in field applications where cost, dust, noise, and other health hazards associated with blast cleaning may restrict its use. While the current example describes a Hypalon-Penetrant coating system capable of room temperature application and cure, other similar systems capable of curing by activa tion with heat may also be developed. Also, attempt would be made to extend the concept to high performance epxoy systems. Accelerator 808 is a commercial product of Elastomers Department and its use in the coatings hinges upon a favorable toxicity and handling assessment. Initial product appli- tion is in the field of Maintenance Paint Industry. Filing Requested By: Dates ________________ Copy to; ' P. H. Pettit, Jr., Exp. Sta. File, Exp. Sta. R. T. Khanna DUP030014312 64 (c> The said composition providing outstanding corrosion protection even on handcleaned rusty steel. (d) The said composition used with or without a durable topcoat for extended service life as a protective coating. (e) The system curing at ambient conditions. (f) The system curing on baking. (g) Pigments in the primer are anti-corrosive, inhibitive, and/or metal flakes. It is possible that a number of different patent applications may be necessary to cover various embodiments of this system. Following examples would illustrate the scope of this technology: Example 1: Penetrant containing Accelerator 808 (or similar compounds) dissolved in toluene in combination with at least one of the following: a. Monomethacrylate such as BMA, LMA b. Piacrylate such as epoxy diacrylate c. Triacrylate such as trimethylol propanetirmethacrylate d. A film forming vehicle. A preferred blend is as follows; Accelerator 808 Butyl Methacrylate Epoxy Diacrylate Solvent Blend % Solids Brookfield Viscosity at 100 rpm Appearance Color 10 60 30 150 40 10 cps Clear Light yellowish Penetrant is applied by brush or spray to marginally clean surfaces. not critical nor is the time required before the primer is applied. Exact amount is Primer: Hypalon 30 is dissolved in toluene at 20% solids. Hypalon contains "ehlorosulfonated" groups on the polymer backbone, which on contact with Accelerator 808 initiate freeradical polymerization of the monomers in the penetrant, resulting in in-situ cured film (without any mechanical mixing) chemically bonded to Hypalon 30. A preferred formulation is as follows: Hypalon 30 Toluene W-128 (Al-flake)60% Solids % Solids (weiqht) P/3 67/100 20 80 22.3 27.3 Primer is applied by brush or sprayed to a surface previously wetted with the penetrant. The surface is coated to a dry film thidkriess of 4-6 mils and exposed to salt spray atmosphere. Mo failures occur even beyond 1500 hours while panels made without penetrant show scribe blistering before 1000 hours exposure to salt spray fog. Tests are continuing. Further development of the concept can conceivably lead to one component system such ass 1) A Penetrant-Primer that^cures in-situ on exposure to light. Photo- polymerization initiator systems are being identified that overcome air-inhibition problem to an extent to make them commercially feasible. DUP030014313 65 2) A Penetrant-Primer that cures in-situ on exposure to atmospheric oxygen. Typically, the product would contain air-drying moieties and polyacrylates. The use of a topcoat containing activating species may be optional, in a suitable formulation, such a topcoat would enhance the cure and performance of a penetrant-primer. We will continue our efforts in this area to identify a preferred patentable candidate. RTK:ayk 4/12/77 DUP030014314 66 APPENDIX VI ACRYLIC MODIFIED PRIMERS WITH ISOCYANATE PREPOLYMERS TITLE: Air-Drying metal protective coatings for rusty steel and marginally cleaned (hand-cleaned) steel eliminating the need for sand-blasting. SUMMARYi The invention can be described in four forms: (a) Pigmented air-drying resins (such as alkyds, epoxy esters and other polymers containing air-drying functionality) formulated with a polyacrylate/meth- ' acrylate (such as trimethylolpropanetrimethacrylate, (TMPTMA), epoxy-diacrylate (XD-9002) provide high solids primer and improved corrosion resistance when applied to marginally clean and porous rusty surfaces. (b) A low viscosity high solids "epoxy" coating without the use of curing agents normally required in the ambient cure coatings. The term "epoxy coating" implies that the major portion ( 50%) of the vehicle in the dry film is derived from "bis-A epoxy" moiety. A formulated primer is fast dry and provides good protection on hand cleaned rusty steel. The absence of water sensitive amine and/or carboxyl group is expected to enhance hydrolytic resistance of the coating. (c) A pigmented composition consisting of a cross-linked network of "alkyd-epoxy ester-acrylates" formulated from a blend of (i) air-drying alkyd, (ii) epoxy ester of air drying fatty acids and (iii) polyacrylate/meth acrylates . (d) A pigmented composition consisting of a cross-linked network of "air-drying vehicle with hydroxyl group isocyanate prepolymer (such as Desmodur N-75, Desmodur E-21 and polyisocyanates such as MDI or TDl-based prepolymers) - polyacrylate/methacrylates. The following examples illustrates the concepts outlined above. DUP030014315 67 Examples of (a) Reference 878E-68-1 Parts by Weight Dulux 67-746 164 TMPTMA 53 Mix Ratio (by volume) 2:1 % Solids (wt.) 87.53 (vol.) 77.00 PVC 23.5 Dry Time 18-24 hrs Corrosion Resistance excellent at 1500 hours salt spray. Note: alkyd modified with polyaerylate. Example of (b) Reference 878E-141-I Parts by Weight Epoxy diacrylate XD-9002 1 TMPTMA 1 Epoxy Ester 786E-68 5 H-44 4 H-172 (.10% in H-44) 0.5 % solids (wt. 54.5 can be increased to 70% by reformulation, clear (unpigmented), can be pigmented. Dry Time 7 hrs Note: epoxy coating without conventional curing agent. Example of (c) Reference 878E-69-I Dulux 67-746 TMPTMA Epoxy Ester 786E-68 H-172 H-49 % Solids (wt.) PVC Dry Time 7.54 2.44 5.00 0.02 5.0 64 c 14.3% 4 hrs 75% DUP030014316 68 -K *> * * *> H * He M H M M M *o <U 1 O vo ft m <U rH o ft I 0) es o> rH 4-1 00 (0 c- i 00 1 rxsj w in CO KO rH vo in in o co CM CO o cm l> GO O CO CM CO o CM r- 00 CM o o o in o o CM CM CM rH 00 rH m O o o If) O O rH CN CN CN rH 00 d) rH X3 f9t rH in in ft >1X5 -H mg RS M 0 o o o> o p H rH rH 10 U U to 1 *0 tJ VO H ft -H s> ft ft EH-H Jft rH CO aa o O o in o cn c n CN CN CN rH I" rH * in <Sh to o n <i o i--I rH ou X! s* rH (Old) p ft as x ; S XJ P rH RS 4H CN 00 1 rH mm to m ft rH rgH *tHJ -gH 0 *rH ,RS} a " >1t ct--n C--N rH 0 C/3 P 4-1 -H >)rj ft .H Bi > # Qft <<X|} CO ft 3 O X3 d> *O I rH ft EH R$ &&' P ft u <v ft +J 4H o H P RfSt P ft d) o ft o o ft 0) ft) o u ft. Cn ft H HJ O d) rH fl> to >1 XJ ffl i--) X) RS HJ CO ft ri R3 RS d) ft to <8 ft 0 d) p 4H -H iH X> rH -H XI P ft O -H Qa O *0 ss rS I ft Q> H R3 HJ ft RS iH d> Q ft He !h rH H H ft O ex +J <fDt ft X2J H* to O > * ^3 dP ft nj on- ^ + ft d) 0) 0) Xa g P oP ft >i *o_a HJ ft r-' S N1 O >1 vo Jh vo tJ i q ft Pi df>t w ex flS o nS X5 rH 0 ft O CO P rH rt 01 d> RS ft p P rH RS Q CO ft -0 OS 0> ft rH ft <D rH OS O rH O nd XJ RS d) H HJ P o CQ RS P ft. P a *h o as P 0> 0 ft d> I to ft o o pft rH RJ P R3 fti H to >nos o 0ft. CN ft I R$ O 8 O rH >lP !> rH RJ H H RS r--a p ft to 5 0 R3 H >i 0 PM U ftirH O RJ He He He He He DUP030014317 69 ADDITIONAL EXAMPLES 878E-148 IjH II* Parts by Weight Primer mill base (878E-148 Dulux 67-H-43034 Alkyd Primer TMPTMA Polyacrylate VG-Y-518 Polyisocyanate BGDMA Dimethacrylate Des E-21 Polyisocyanate % Solids (wt.) (vol.) approx. Dry Time, hours Appearance Gel Time, hours 90.82 164.0 33 30 40 85.3 70+ 6 Smooth >4 90.82 135.0 32.1 20.0 85.5 70+ 1 1 Preparation of Primer Mill Base (878E-148) RC-60462 H-253 H-446 H-457 VH-67552 VD-5822 H-173 Sicorin RZ Zinc Molybdate Total % Solids (wt. Parts by Weight 18.82 11.74 5.78 2.45 0.38 1.19 0.46 10.0 40.0 90.82 80.4 * Dry time and pot life are adjustable by proper selection of the driers, catalysts, retarders and inhibitors. DUP030014318 70 DISCUSSION: Linseed oil and alkyds made therefrom with red lead or zinc chromates are commonly used primers for marginally prepared rusty surfaces. Reasonably good corrosion protection is obtained from these systems but failures are normally seen as blistering and breakdown of the film integrity because of poor chemical resistance of the film. Corrosion protection of these systems is considerably enhanced (2X+) when these are used in combination with polyacrylate or polymethacrylate. Examples of such acrylates/methacrylates are a) Trimethyiolpropanetrimethacrylate (TMPTMA), b) Epoxy-diacrylate (XD-9002), c) Butane dioldimethacrylate (BDDM), and d) Other acrylic monomers or their adducts. The resultant formulated products show i) improved dry, ii) iii) iv) enhanced corrosion protection ; high solids 70% volume solids low viscosity. The system offers wide formulating flexibility in the speed of drying and cure. Among the additives that can be used are the driers, anti-skinning agents such as oximes and isocyanate prepolymers. Nominally the dry time is adjustable between 4-16 hours by proper formulation. Excessive crosslinking functionality can result in film-embrittlement and need to be balanced so that a commercially useful product can be developed. This can be done by one or all of the following schemes: a) blending polymethacrylates with di- and mono methacrylates b) using soft air-drying vehicle, such as long-oil alkyds c) adding flexibilizing additives such as nonleaching plasticizers and polyols. The primers based on these systems normally have excellent dry adhesion to steel surfaces. Their adhesion may further be augmented by using amino-functional additives or reactive prepolymers. DUP030014319 71 PUBLICATIONSi This is an. extension of Du Pont's effort in polyacrylate modified air drying alkyds originated by Phillips Heiberger and currently followed by Ken Leavell. The invention of this patent request is that these compositions can (i) enhance corrosion resist ance, (ii) yield a higher solids system and (iii) provide rapid dry coating system. It would be appropriate to examine current patent applications in this area and to include the unique perform ance properties identified in this application. One patent recently issued to Celanese (U.S. 4,014,830) where the amount of polyacrylate employed was limited to less than 10% and no claim was made to improved corrosion resistance of the primer based on this technology. It would be evident from detailed examination of this application that the subject application can be subdivided for easier patentability. The unique feature in this application is the polymerization of acrylic monomers or prepolymers in thin films ( 10 mil) in the presence of atmospheric oxygen and improved corrosion resistance of the primer made from these vehicles. IMPORTANCE OF THE INVENTION; Coating rusty steel without elaborate cleaning such as blasting, abrasive grinding, polishing, and/or careful metal treat ments (chromate or phosphate) has been an unattainable goal for a long time. This is an initial effort to identify systems that would provide extended service life under corrosive atmosphere. It is an alternative to sand blasting in field applications where cost, dust, noise and other health hazards associated with blast cleaning may restrict its use. While the current examples describe an ambient cure coating system capable of in situ and thin film cure, other systems of improved corrosion resistance but cured by activation with heat may also be developed. Also, attempt would be made to extend the concept to primers for automotive end uses. TMPTMA is a commercial product (Rohm & Haas, and SarotOmer Chemicals) and other similar polyfunctional monomers are available. Their use in the coatings hinges upon a favorable toxicity and handling assessment. Initial product application is in the field of maintenance finishes. A successful patent application would give us significant product advantage. DUP030014320 Copy No. 1 2 3 4 5 6-8 9 10 12-13 14 15 16 17 18 19-21 22 23 DISTRIBUTION LIST Full Reports K. A. Saegebarth, F & F, Wilmington G. I. Mulholland, F & F, Wilmington J. E. Griffiths, Legal, Wilmington J. W. Gkonos, F & F, Marshall Lab R. W. Laurrell, F & F, Marshall Lab Library, F & F, Marshall Lab (3) W. S. Zimmt, F & F, Marshall Lab F. M. Gavin, F & F, Troy Lab Central Report Index, ISD, Centre Road M. A. Perse, CR & D, Exp. Sta. D. M. Marsh, F & F, Exp. Sta. R. E. Fay, F & F, Exp. Sta. J. M. Donatello, F & F, Exp. Sta. R. B. Ware, F & F, Exp. Sta. File Room, F & F, Exp. Sta. (3) P. H. Pettit, Jr,, F & F, Exp. Sta. R. T. Khanna, F & F, Exp. Sta. (2) First Parts N. Pappas, F & F, Wilmington W. W. Kaminski, F & F, Wilmington) _ J. S. Harrison, F & F, Wilmington) n E. Gonick, F & F, Wilmington K. R. Miller, F & F, Wilmington O. H. Bullitt, Jr., F & F, Wilmington W. R. Hendrix, F & F, Wilmington F. A. Fluegge, F & F, Fairfield R. K. Smith, F & F, Troy Lab A. F. Nugent, F & F, Troy Lab L. W. Crissey, F & F, Troy Lab C. D. Smith, F & F, Marshall Lab C. H. Knop, F & F, Marshall Lab (50) Supervisors, Associates, and Fellows, _ rurn F & F, Exp. Sta. RTKslms DUP030014321