Document 8Rzx5Bxbwd2g6EYNOy6qj9Gy

<L~--t Ji29'5 NOT FOR aRCUUriON PATE: JTJKE JO, REPORT NO. 906 pa- *7*4* PARLIN LABORATORY REPORT SUBJECT: STRIPPABLE PROTECTIVE SPRAY COATINGS NAVY RESEARCH CONTRACT NOrd-52l6 PERIOD: JULY I, 19U4 TO JUNE 30, NOTEBOOK: NOS, 1091, 2081 AND 2098 PREPARED EK: C G> MURPHY APPROVED BY: J~ Po SERMATTEI N 29344 CONTENTS I- * II ~ INTRODUCTION RESULTS AND CONCLUSIONS Ill - EXPERIMENTAL IV ~ PHOTOGRAPHS AND CHARTS DUP030001010 CLASSIFIED - RESTRICTED mmc?SE*"8 D0CUMBNT ^at n s asE<ss? u w d e r p a t e n t OFFICE PAULIN LABORATORY REPORT NO, 906 SUBJECT: STRIPPABLE PROTECTIVE SPRAY COATINGS NAVY RESEARCH CONTRACT NOrd 5216 I ~ INTRODUCTION This report covers the results of the experimental work done under the subject research contract for the period July 1, 191*4 to June 30, ' 1945* *t supplements Parlin Labora tory Report No0 $00 which covered the initial experimental work done on this problem from January 1 1944 through June 30, 1944' In the first phase of this work as covered in Report No,, 90* 311 investigation was made of the most likely candidates among the then available film formers (with the exception of the "Vinylites") from which a atrippable sprayable protective coat ing could be formulated. Investigation of the "Vinylites" was not undertaken at that time in order to avoid duplication of the war'*1'2b3e4in5g6 done at the Naval Ordnance Laboratory at Silver Spring, Maryland. In this first phase of the work, the follow ing film formers were investigated: ethyl cellulose, nitrocellu lose, cellulose aceto^butyrate, neoprene. Buna S, Buna N, butyl rubber, polyvinylbutyral, and the $0J$O interpolymer of n-butyl isobutyl methacrylate,, Of these, sprayable strippable jr 0tective coatings were developed based on ethyl cellulose, nitroncellulose and neoprene, all of which showed promise of meeting the general requirements far coatings of this type.. This report covers the results of experimental work done along the following lines: (1) Field testing of the ethyl cellulose, nitrocellu lose and neoprene type coatings, (2) General evaluation of the "Vinylite" resins for use in strippable sprayable coatings (3) Improvement in the durability of NOL-193 lacquer meeting Specification 0S*>3602 , (4) Development of adhesives to adhere vinyl and neo prene type strippable coatings to steel, (5) Evaluation of the ingredients used in formulat ing NOL-195 stripping lacquero (6) Development of a dipping type vinyl stripping lacquer* DUP030001011 '2' II - RESULTS AND CONCLUSIONS As a result of further laboratory work In studying the "VinylUe* resin as the main film formers In sprayable strippable protective coatings and of field teats conducted on the ethyl cellulose and neoprene types, it Is felt that the vinyl resins (chloro-acetate copolymers) offer the most promise in formulating such coatings for most purposes, and especially in cases where a combination of toughness, corrosion resistance, durability and a low moisture vapor transmission rate is de sired* The selection of the grade of resin, type of plasticizer and other modifiers is dependent on the use to which the coat ing is to be put . For the main purpose which Naval Ordnance is propos ing to use such coatings f. the formulation known as NOL SS-193 (Specification 0$-$602j developed by Lt.> VmH.Holst and his group at the Silver Spring Naval Ordnance Laboratory Is felt to have the best combination of properties with the pas sible exception of durability; A modification of this formulation in iflilch a more soluble resin (VYNS) is used in place of a dif ficultly soluble resin (VYNL) is thought to have some advantages over NOL SS-193 with only a minor saorifice in film properties.. Thes^ advantages are in ease of manufacture, higher solids at spraying viscosity, and in better solution stability,, Such a composition, known under the dUPont experimental code J-130CWC 711^7;, Is being field tested by the Navy at the present time,. Exposure tests indicate that the outdoor durability Of both NOL SS-193 and J-1300-X7147 can b definitely Im proved by pigmentation with carbon black, Other pigments and pigment combinations can undoubtedly be used to improve the durability * Exposure studies covering such potential pigment combinations are now underway,, There is evidence to Indicate that sufficient durability for moat purposes may be obtained by using a pigmented composition only as the final topcoat Expcs ure tests are also underway to determine the minimum thickness of pigmented topcoat which will be required , From.the exposure tests already examined some In formation on the relative durability of stripping lacquers based on various film formers is available* These- tests in dicate that they may be listed in the following order of in creasing durability; viz,,, ethyl cellulose, nitrocellulose and neoprene, vinyl * The best ethyl cellulose composition we have been able to formulate has a durability equivalent to four months In Florida, the neoprene and nitrocellulose types have a durability equivalent to at least one year and probably longer in Florida, while the vinyl types are expected to be slightly superior to both the neoprene and nitrocellulose Because DUP030001012 these compositions are stripping lacquers and failure is con sidered to occur when the film is too brittle to be stripped from a iptl2* panel in one piece# these life expectancies represent a higher order of durability than would be expected from permanent finishes.. The above conclusions are drawn from films in the range of'8-12 mils thielcness so that in the case of the NOL SS-193 type application where the film thickness is on the order of mils# considerably longer useful life can be expected. For uses other than that of bridging openings and enveloping irregular pieces of equipment and for use where the protective film comes in direct contact with the equipment to be protected# several other vinyl type coatings have been developed. These compositions have lower tensile strength than the NOL SS-195 type, but at the same film thickness are equiv alent in corrosion resistance*, moisture vapor transmission rate and durabilityo Two typical compositions are known under the duPont experimental codes J~2OO~X-'7C0-2 and J-200- 7182 ,, They vary from the NDL SS-193 formula mainly in that they contain polymers of lower molecular weight and lower vinyl chloride content. The advantage of using such resins lies in their better solubility which yields higher solids at spraying vis cosity and better sprayability< Their disadvantages are that they are not quite as tough and do not have quite as good cold-crack resistance,, It is felt, however, that they are as good as it is necessary to have them in these respects . For. the NOL SS-193 type of formulation the present solvent used (methyl ethyl ketone) appears to be satisfactory for most conditions of application.. However, it may be de sirable to use a small amount of methyl isobutyl, ketone where the application is made under conditions of extremely high humidity and high temperature6 Other solvent combinations are being investigated and preliminary results: indicate that acetone/toluene/methyl isobutyl ketone and toluene/methyl ethyl ketone mixtures hold some promise.. In the J-200<*>Xm'012 type of formulation a slower solvent combination is recommended as freedom from bubbling in the film is of more importance a3 a considerably thinner film is applied (10 -15 mils)* Dioctyl phthalate appears to have the best combina tion of properties when used as the plasticizer# but for some applications, such as in the >200->X 7012 type# trleresyl. phosphate can be used-. Rustban 603 seems to be more satis factory than an ordinary refined mineral, oil such, as Fractal or Estie (Standard Oil of N<,JV). This is particularly true in the NOL SS-193 type of formulation . DUP030001013 Two organic, compounds, Stabilizer A and Salol, were evaluated in the cleat* formulations for their stabilize ing effect against heat and light in order to improve the durability of the clear films,* Stabilizer A, the monoglycer ide of a vegetable source of fatty acid manufactured by BF0 Goodrich,* gave only a very slight improvement in durabil--,' ity, while Salol (phenyl salicylate obtained from Fisher Scientific Co,*} was only very slightly better than Stabilizer A This improvement was evidenced by slightly less darkening of the film at the end of two months* exposure in Florida and was a very minor improvement as compared to the effect of pigments*-, tion Preliminary laboratory testa indicate that a cold dip vinyl stripping lacquer may have some advantages over the cold spray type or a hot melt type such as the ethyl cellulose hot. melt developed for Army Ordnanoe (Specification AN0-117-A) Formulation J-200~X-*7012 referred to above, has been recommended for this purpose and is now undergoing tests at the Naval Ordnance Laboratory, Silver Spring, Mdo Considerable search and experimentation indicates that the most satisfactory adhesive for use in adhering the NOL SS-193 type of film to the base of equipment to be pro tected is a phenol-formaldehyde modified butadiene/aorylonitrile type as represented by "Gaytex* or rtpliobond*<, Although this type of adhesive is somewhat thermoplastic and it would be desirable to use an adhesive which would convert on aging to the non-thermoplastic state, tests indicate that "Gaytex" or *PliObond*roay be adequate for the intended purpose,. Pre liminary work to develop a self-converting type of adhesive has as yet met with no success * However, laboratory tests indicate that there are two means of improving the resistance of a "Pliobond" bond to loosening under a?load at elevated temperatures,) The use of Estio #1^ oil in the- NOL SS-193 formula definitely improves the resistance to failure at ele vated temperatures, and the deletion of VYNL resin from the NOL SS-195 also gives a slight improvement,* For adhering the neoprene type stripping lacquer to steel, the problem is more simple , Fairprene Cement #5115 (duPont Gompany) gives bonds whi<$i appear to be satisfactory jjowever, stronger bonds can be obtained with a chlorinated rubber cement such as Fairprene #51014. or an experimental cement such as j-N-205-12 also made by duPont* In the previous report (No,,900) the use of small quantities of surface active agents such as sodium petroleum sulphonate and soya lecithin was discussed with respect to DUP030001014 their influence in reducing the adhesion of the stripping lacquers discussed therein . Some further work along the"line of obtaining 11controlled adhesion" in the vinyl type stripping lacquer has been done.; Normally the vinyl chioro-acetate resins yield stripping lacquers with very poor adhesion to most substrates and in some applications it is necessary to increase the ad hesion so that the film will not be stripped from the sub strate by. the wind when the film is accidentally ruptured-, It has been found that "Vinylite" VMCH (believed to be a vinyl chlcro-acetate intarpolymer with which a small amount of maleicacid has been copolymer1 sad) can be added to a vinyl stripping lacquer to give any desired degree ;>fadhesion.. This effect is, obtained, however? only in the"absence of a surface active agent such as soya lecithin or BOdium petroleum sulphonate as tests show that when both are used the latter are'more effective In reducing adhesion than VMCH is in increasing it, In this connection it is interesting to note that. Rustban 603. a rust inhibiting oil which is believed to contain sodium petroleum sulphonate, improves corrosion resistance of a vinyl stripping lacquer as compared to a refined mineral oil containing no surface active agents such as Estic oil* These results are contrary to those obtained when sodium petro leum sulphonate is added to an ethyl cellulose or 'nitrocellulose type stripping lacquer as in these cases sodium petroleum sul- phonste has a deleterious effect on corrosion resistance.., The possibility of developing a webbing agent or lacquer having webbing characteristics equal to or better than Solution A (NOL SS-193) has been investigated. None of the polymers examined had as satisfactory properties as Solution A, but a lacquer based on a mixture of polyvinylbutyral and poly vinyl acetate has working properties which approach that of Solution A and might be considered a secondary alternate composition . Ill EXPERIMENTAL In the experimental, work on the subject problem as covered in Parlin Laboratory Report No,. 9^0* which did not include any work with the "Vinylite" resins for reasons previ ously mentioned, the three most promising film forming mater iale of the candidates studied were ethyl cellulose, nitro cellulose and neoprene.. Stripping lacquers based on these fiii formers in laboratory tests had -such desirable properas s): r 'vysbilIty, strlppability, durability and provided good protection from corrosion to steel teat pieces when .subjected ic nigh temperaturs/high humidity, high temperatura/salt spray and ether aimiiar tests However,, the following described DUP030001015 field tests on the ethyl cellulose and neoprene types plus; the results obtained from a study of the "Vinylitee" ir/ilrete that the latter are for general use more promising fill-, former? for stripping .lacquers . la Field'Tests Field .tests were rv.: on the ethyl cellule?*! ana - prene types at (1) the U.S-.Arroy, Air Base#* Newark.-. N....T-, a..,o ?_). the TJt.SoNavy Yard; Philadelphia P.: A TJvS.-Army Atlantic- Ovei'seao Air .Service Command _____ Newark Aray^Air Base- Newarkj, N,,J,. __________ In this test- J-SQO -3f-.<>657 ahd J 200 X'-t'639i strippi r. /. lacquers based on ethyl cellulose and neoprene reapertt.ive.iy,, were tested as temporary protective coatings for packaging fighter planes intended fqr shipment overseas as deck cargo on freighters end tankers-, The ethyl cellulose lacquer* ij .200- X--663?, was ap plied. to & camouflaged P-U7> Thunderbolt, by spray application with a reexilttng film thi tkneas of 10- -12 mils in fi ve 3pray coats,. Forty, one gallons of lacquer and, eight gallons of thinner were required to complete the job-, When tested for atrippability at the end of 2k hours, the film wav readily strlppable and the coated plane was 0 X-.* d for shipment, tc the Cth.ea.tir by Colonel WE,.Ni .-cl? Chief of Maintenance-. However, the ethyl, cellulose film was act as tough and rubbery as the vinyl type regularly being used at Newark "for this pur pose, and for this reason it was felt to be inferior to thavinyl type. The neoprene stripping lacquer, J.-200. X -66.59; was applied to an unpainted Mustang, by spray application, to give a film thickness of 940 mils in five spray coats Twenty-five gallons of lacquer and five gallons of thinner were required t;e complete the job On this pia ne it was be,, cided to hold, up shipment until it could be determined that the film would strip., Normally this would require a period of two weeks at a Minimum temperature of 75F-. At the end of two weeks the film was strippable In scrae areas, but not ir. ox-ners.. A check on the st-rippabiiity two weeks later showed little in provement and it was decided to strip the film off and to package the plane in the normal manner..- Aa later laboratory tests showed... the failure of the neoprene to fully vulcanize sad acquire enough f.\\m Bt.vengtb tc- be ruadily scr-ippable -was due to the low temperature prevailing at that tim^ (Sec Chart IV at end of tbia report } Mo v-cu'--srhad it beer fully DUP030001016 "7" vulcanized It would still have been Inferior in film strength to the vinyl type then being used at Newark. It did, however, have good abrasion resistance^ B - U^S .Navy Yard; Philadelphia,. Paa The neoprene composition was also field tested aboard the UoS-S,North Star at the U-,S-.,Navy Yard., Philadelphia/ Paw Here it was tested as a protective coating for packaging topside equipment aboard ships laid up for storage In thi.3 test, a range finder wa3 packaged in the following manner: A web, sprayed from a mixture of Solutions A and B (NOL SSTM193_) was used to first envelop the range finder The neoprene solution was then applied by spray application over the web tc a film thickness of I4.0 mils . Nine gallons of neoprene lacquer were required. The package was then opened and silica gel placed inside, together with a humidity indicator and a polished ij.0 mm projectile.. A "Vinylite" sheet (0, 064 inches thick) wa3 then sealed into the package to act as a window,. At the end of four months exposure, at which time all the test packages were removed from the tUS-S.North Star, the neoprene package was still in good shape with no rust on the projectile and the indicator showing an inside relative humidity of less than 30% . In this application the neoprene type stripping lacquer was inferior to the NOL SS-193 type mainly In application properties; as more skill and care are required in order to g9t the proper degree of tautness. It also ha3 lower tensile strength, but at the film thickness at which it was applied, this difference may not be serious Further field tests are underway at the Naval Air Experimental Station, U .S-Navy Yard, Philadelphia,pa-, on the ethyl cellulose, neoprene and a vinyl type stripping lacquer as temporary protective coatings for aircraft component parts during outdoor storage.. These coatings were applied by spray to painted aircraft wing sections at a film build of 12 >-->15 mils and have been on exposure at Philadelphia since December 1944.0 No results of these tests have been communicated to the writer of this report as of this date , ' No field tests were conducted on the nitrocellulose type c>f strippable coating because of its well-known in- flammability., However, exposure tests indicate that this typo Is definitely more durable than the ethyl cellulose type, equal or slightly more durable than the neoprene, and may be equally as durable as the vinyl type , , DUP030001017 Based upon the results described above and labors tory evaluation of the "Vinylites" as described, below, it'is felt that for most purposes the vinyls represent the mo3t promis ing of the film formers yet examined for use In sprayable, strippable, protective coatings., In order to study the durability of the NOL SS 195 stripping lacquer and various modifications of it as well, as to compare it with the neoprene type stripping lacquerr a aeries of miniature packages (suggested by the Naval Ordnance Labora tory at Silver Spring.: Mo) have been prepared as described be low and are now on exposure at Pariin . The packages consist of one cubic foot "dog houses" which have been enveloped with a web sprayed from a mixture of Solutions A and B (NOL SS 193) ever which waa applied the vari ous topcoat and topcoat systems listed below0 The films were sealed to the base with Tygon TP107A Adhesive., The package wa3 cut open and a IjO"nun polished projectile, a one pound bag of "Silica Gel" and a humidity indicator were placed inside0 A thermometer was also placed in the films marked with an asterisk (*) in the table below A rigid "Vinylite" sheet (o06i|. inches thick) was sealed over the ipdj." opening to serve as a window. The films were sprayed to a thickness of 30> itO mils.. The following films are being tested? (1) NOL SS-193* (2) NCL SS-193 plus aluminum paste* (3) NCL SS193 pigmented with carbon black* (4:) NCL. SS-193 pigmented with titanium dioxide/lampblack* (5) Alternating coats of NOL SS'=>193 pigmented black and yellow (lead chromate) with the black as the final coat . (6) Black (carbon) vinyl based on VXUS/VYHB (25/?5) ard plasticized with trieresyl phosphate., (7) Aluminized vinyl {%) based on VYNS/VtHH (25/75) and plasticized with trieresyl phosphate,. (8) Gray vinyl (titanium dioxide/lampblack) based on VYNS/VYHH (25/75) and plasticized with trieresyl phosphate,. (9) Alternating coats of a black (carbon) and yellow (lead chromate) vinyl with black as the final coat Both formulations based on VYNS/VYHH (25/75) and plasticized with trieresyl phosphate, (10)Clea.r modification of NCL SS' 193 containing straight VYNS (J- -1300. X 7147) =. (11)Composition used in (l,.) but pigmented with carbon black (12)Clear modification of NOL SS-193 in which Estic #44 oil is used in place of Rustban 603 , DUP030001018  9" (13) Composition used in (12) "but pigmented with carbon blacks (14) Clear modification of NOL SS-193 in which Es?i.~. #44 oil is used in place of Rustban 603, and in which VMCH is used as 10# of the resin replacing VTNS (15) Composition used in (lit) but pigmented with carbon blACk'i (16) Thirty mils of NOL SS "193 followed by 10 mils of carbon black pigmented NOL SS-193 > (17) Black Neoprene Stripping Lacquero (18) Aluminized Neoprene Stripping Lacquer These packages have now been on exposure for three months and all appear to be in satisfactory condition with the relative humidity in all packages being leas than and none of the steel proijeotil.es showing rusto A recent check on the temperature variations in the packages having no pigmentation, pigmented blacky gray and aluminum gave the following results; (1) NOL SS-193 dar (2) NOL SS-193 pigmented black (3) MOL SS-193 aluminized (4) NOL SS '193 pigmented gray Inside .. 102 F 100SP . 103 p Outside 0?,; 90 F.. 90?,, 90p ,, Because of the apparent inconsistency in the above temperature readings it is felt that in order to get truer data on the effect of various pigments on heat absorption, it may be desirable to run field testa on packages having a larger .sur face area,. In addition to this we are planning on running some tests to determine the temperature of stripping lacquer films pigmented gray, black and aluminum when exposed to direct sun light o 2o General Evaluation of the Vinyl Resina The evaluation of the vinyl chloro- acetate copolymers for use in stripping lacquers indicates that two general types , are desirables (1) one type based on the high molecular weight/ high vinyl, chloride content copolymers such as used in NOL SS-193 for use where wide openings are to be bridged and the film is for the most part unsupported, and hence must ha\ i maximum strength and maximum col'd-craok resistance; and (2) one type based on more soluble:, lower molecular weight,, lower vinyl chloride content copolymers as represented by J-2C0 X-70j u : for use where the film for the most part ia to remain in con tact with the surface of the equipment to be protected DUP030001019 ao- Three typical compositions ax*c shown below; For us where the film will be unsupported ~ J 2QQ-X-7151 (NOu SS-193 pigmented) "Vinylite" VYNS "Vinylite* VYNL dioetyl phthalate Rustban 6O3 Stabilizer A carbon black 10o9% 2.8 5r>5 3*4 (Standard Oil of N.J..) Ooj (B F,Goodrich) 2.1 methyl ethyl ketone ^5 <0 For use in direct contact with surface of equipment to be protected ~ (a) J- 200-'X 7012 "Vinylite^yyNS ~ "Vinylite* VYHH tricreeyl phosphate Estie #44 oil Stabilizer A lampblack methyl ethyl ketone toluene methyl isobutyl ketone 5,.'}% 15.-9 8.3 1-7 0,4 3.2 2&o0 13v>0 26 rjO (b) J-200. x >7182 ,,Vinylitew~raS "Vinylite* VYHH "Vinylite* VM3H dioctyl phthalate Estio #44 oil Stabilizer A lampblack methyl ethyl ketone methyl isobutyl ketone 8,2* 8.0 0,,3 6 -.6 I06 C'.,3 2-/3 37 b 25-1 Formulation J-200-X-7131 is the recommended pig mented modification of NOL SS 193 and Is designed to impart maximum durability- Formulations J-200--X*'7012 and J 200-X 71,82 are representative of the type which is applied in direct con tact'with the surface tc be protooted-. The latter, J-2CC- X 7x82, is formulated to have a better cold-crack' real stance than J-200"X-'>7Q12 * and to have an adhesion tc Aided of 1 3 to 7. X pounds per inch-. .A eacrsf ice in' total solids at spraying via cosity' is required to obta in the improved cold -crack ro-X :> ^!:>ce. DUP030001020 -11' The following are the results of laboratory eval.ua tion of the vinyl resins which led to the development of the above formulations : A Resixw Threw grades of "Vinylite" resins are available from Carbide and Carbon Chemical .Corporation which lend themselves for this purpose Thsy are* VYML a copolymer of vinyl chloride and acetate having a vinyl chloride content of 93~95$ and an average molecular weight of 2k, 000 0 \ VYNS ' a copolymer of vinyl chloride and acetate having a vinyl chloride content of 88 >5-90.>5$ and an average moleculap weight of 1.6.000,, VYHH copolymer of vinyl chloride and acetate having s vinyl chloride content of 8.5- 88$ and an average molecular weight of 20..000 .' s A comparison of the physical properties of three typical compositions containing them are as follows: 2098 189 ! "Vinylite* VYHL ~~TW "Vinylite" VYHS 119 "Vinyllte* VYHH dioctyl phthalate 60 Rustban 605 3o? Stabilizer A 0-3 methyl ethyl ketone ?5,,0 iT$rn% total solids 25- 0% vise0(#15 DuPont cup) 24 sec tensile strength 195G psi' elongation h.00% MVTR (50 mils) 55 grama 2098-189-2 16*5 66 4.>i 0,5 72,5 275$ 22 sec* 2865 psl hzof 29 .grams 2098-189' 3 w* 1 5o3$ 15*7 8., 4 54 ) Oak ) 65o O 2315 >s0e$c., 1600 psi 395% 29 grams Ratio 10o0 4c 0 2o7 -*MVTR grams/lOC square meters/hro at 59->5Ov UDder a vapor pressure differential corresponding to 100$ relative humidity on one side of the film and less than 5$ on the other side Prom the above results it can be seen that where maximum film strength is required with maximum tautening effect (see Photograph I at end of report) the higher moletul'.ar weight resins should be used At the same time a higher degree of chemical inertness and flexibility at low temperatures l* ot> talned, These .properties are gained, however.-, at the ?xper.1 of solubility (tbtai solids at spraying viscosity), solution stability and sprayability.-. DUP030001021 - 12 - The relative durability of each of these resins is being studied by exposure in Florida but no significant results are as yet available Another of the nVinylits" resins examined was vacs, not. as the main film former, but as a'modifier to increase the adhesion . *'Vinyl ite* VMCH is believed to be the same as VYHa except that a small amount of maleic acid has been introduc ad into the polymer during the polymerization process,. The ex fee of this resin on adhesion can be illustrated as follows when added in varying proportions to a stripping lacquer based on a l/l blend of VYNS/VYHH and plasticizer 10/Ij. with dioctyl phthalateo ' ' Composition 0% VMCH 1% VMCH on resin 2% VMCH * li$ VMCH * i.0% VMCH tt " \0G% VMCH Adhesion adhesion too low to be measured with. available equipment 1500 grama/inch width - I.585 graps/ineh width ''* 196 5 grams/inch width ^ /I? grams/inch width ~ cannot be stripped This effect only takes place in the absence of a surface active agent such as contained in Ruatban 605, as with this oil present even with straight VMCH in the ratio of 10 parts resin to one of oil* the adhesion drops to ij.50 grams/inch width. Preliminary results indicate that the use of VMCH in quantities up to 10j of the resin does not have a deleterious effect on corrosion resistance or moisture vapor transmission rate and that it may even have a beneficial effect,. Its effect on ultimate durability is being studied,, B ' Flaatic-izera A number of plasticizers are being evaluated for use with the vinyl resins* among'which arej X,,. dioctyl phthalate 2 , trioreayl phosphate 5 Paraplex G-\25 .' Ip-, dibutyl sebacat-e 5., dioctyl sebac&ts methoxyglyc-ol. a/etyl ricinol.eate DUP030001022 -1.5- The best .all-around plasticiser appears to be dioctyl phthalate, although we do nor; have the durability experience with, it that we have with irieresyl phosphate.-, Dioctyl phthalate gives the best combination of flexibility over a wide range of temperatures# pliability* arid lour mois ture vapor transmission rate.. Tricresyl phosphate is inferior to dioctyl phthalate mainly in flexibility at low temperatures Dibutyl sebacate while returning better low temperature flex ibility than dioctyl phthalate slightly impairs the MVTR and is inclined to be slightly, more volatile.. Paraplex G-25 and methoxyglyool aoetylrioinoleate have poorer low temperature flexibility than dioctyl phthalate and there are indications that the methoxyglycol. acetylrieinoleate returns poorer durbii> ity., Dioctyl sebacate, contrary to the man ufa:; tuner' s (Resinotia Products) claims- did not return as good cold-crack, resistance in our tests as did dioctyl phthalate when used in vinyl stripping laoqWr formulations C - Oils . Two types cf oils have been evaluated for use in vinyl stripping lacquers; viz.,- Rustban 60J and Estio oil,-, Both oils have a place in the formulations depending upon the use to which the coating is to be put Rustban 6OJ while having the advantage of promoting corrosion resistance, returns a slightly higher MVTR and in uses where the film is to be adhered to the metal with an adhesive, it impairs the heat resistance of the bond (see dis cussion under "Adhesives" in latter part of this report) , It also cannot be used when a definite degree of "controlled adhesion" is to be incorporated in the film.. Such an applica tion is as a protective coating for use in direct contact to equipment intended, for outdoor storage or shipment , Here, if the adhesion is too low, there is danger of the film being stripped from the equiproen t by the wind It the film is accidental ly ruptured. D" Stabilizers An evaluation of a number of stabilizers, both organic and inorganic is underway to determine their stabiliz ing effect against heat and light with the view of improving the durability of the vinyl stripping lacquers.. Among those being evaluated ares Organic. "STafciIize.r A (the acnogi of a vegetable 3cur-' fatty acid manufactured by B F-.Goodr-i Sb Co j, Salpi (phenyl salicylate} DUP030001023 "14- Inorganic blue lead red lead litharge lead chromate lead titanate antimony oxide Both Stabiliser A and Salol appear to have a alight atabilizing effect eapecially in clear lacquers. There are indications that on outdoor exposure Salol may be slightly superior to Stabilizer A, but the improvement ob tained with both is very small compared to the effect of such pigments aa carbon black In addition both improve the cor rosion resistance > This beneficial effect is definitely noticeable in vinyl lacquers containing Estic oil and is . not so noticeable in formulations containing Rustban f>05 In. this respect Stabilizer A is slightly more -beneficial than Salolo Exposure tests in Florida have also not gone far 'enough to draw any conclusions regarding the effect of the inorganic type stabilizers on ultimate durability, There are some indications that the lead pigments may have a deleterious effect on corrosion resistance This points however9 is being checked E < > Pigments Several pigments and pigment combinations are now undergoing evaluation to determine their effect on the durabil ity of vinyl type stripping lacquers, These are carbon blacks: lampblack, titanium dioxide/lampblack? lead chromate,- cadmium sulphide and aluminum,- with and without stabilizers Although the exposure series have not progressed to the point alieredefinite conclusions can be drawn,- the evidence obtained so far indicates that pigmentation definitely improves the durability of '& vinyl type stripping lacquer and that carbon black pigmentation offers the best possibilities, of giving a, film Its maximum durable life , Photograph III at the end of this report shows the beneficial effects to be gained by pigmenting a clear vinyl stripping lacquer.. The panels shown in this photograph were coated to a 10 mil film thickness with a vinyl stripping lac quer composed of "Vinylite" VIHH 10 ,o/tricresyl phosphate - 30/Sstio #i}4 oil < 1 .0. t The panel, on the right was pig mentad with carboys black/red lead, the one on the left with titanium dioxide/lamp!lac.k/ced lead, while the one in the center is unpigmantsd All were exposed nine months in Florida at a hJy* angle facing south- The two pigmented modifications DUP030001024 -15' are still readily strlppable, have retained a fair degree of flexibility and have protected the steel substrate iron; coi* rosion , The clear> however^ has become dark and very brittle and has flaked off the panel which is badly corroded,. This deterioration of the film was apparent at the end of one month's exposure at which time the clear film showed surface checking, had darkened, and the steel substrate began to s hew signs of rusting- Photograph II shows four microphotographs of films of clear and pigmented NOL SS '195 stripping lacquers which have been exposed three months in Florida as unsupported films on wooden frames.. These films were sprayed over the web coat- to a film thickness of approximately 4O mils. The clear film is the only one showing signs of deterioration, evidenced by 3xoall surface checking and darkening. Photograph (a) is the clear before exposure while (b) is after three months* exposure Photographs (c) and (d) represent the clear pigmented with carbon black, and the clear with a 5 mil thick topcoat of a black pigmented vinyl stripping lacquer*. Neither show any signs of deterioration. (The difference in smoothness which is noticeable between photographs (c) and (d) is due to dlf~ ferences in spray application and existed before the films were exposedo) This would indicate that perhaps only a top coat of nils of a black pigmented vinyl stripping lacquer is all that is necessary to give the desired degree of outdoor durability,, Vinyl stripping lacquers pigmented with titanium dioxide/lampblac-k and with lead chromate also give evidence that added durability can be imparted to a clear with these pig ments, but it is not expected that they will return as good durability as can be obtained with carbon black. Modifications of the clear pigmented with cadmium sulphide were better than the clear for durability also but show signs of beginning to fail at the end of four months* exposure in Florida-, The use of aluminum flake is not being recommended at this time as there is some evidence that it weakens the corrosion resistance of the film, It does, however, tend to decrease the MVTR but the amount of aluminum needed to obtain an appreciable decrease in permeability also tends to reduce the toughness of the film by decreasing its tensile strength and elongation.. However, it may be that a final topcoat of an aluminized vinyl lacquer over the clear may be desirable, particularly because of its ability to reflect rather than absorb heat and light It Is recommended that field tests be DUP030001025 -l6TM made on large pieces of equipment to check the dif.forence in the heat absorbed in the pa ckage 'when tope oated wi th black;, gray and aluminum vinyl lacquers , F Solvents The following work with solvents has been done or. the vinyl stripping lacquers both for the NOL SS-193 type and the J-200 X--7012 type. In the NOL SS-193 type straight methyl ethyl ketone can be used with satisfactory results for most conditions of application,. However., when the lacquer is to be sprayed under conditions of high tenparature/kigh. humidity, the use of small amounts of methyl iaobutyl ketone is recommended Several batches of NOL SS 195 have been formulated with other solvent compositions and their effect on speed of solution, apray&bility, properties of the sprayed film, and stability of the solutions have.been noted All except No>5 blend shown below appeared to be promising in the event sufficient methyl ethyl ketone is not, obtainableo Listed below each blend xs the viscosity of the NOL SS-193 solution obtained initially and after aging,. MEK KIBK toluene "cetone 12 l730 C. 5 10 20 ". to -.w 30 ko 1 6 1** 50 10 20 20 .3 it 8-tHt 10 27 63 original vise-,* after 5 days after 1 month 17" 20* 20" 2hn 25* 19" 20" 19 HI 22 27 55 2k 20 19 21. 2.3 26 34 2b 21 20" 21 21 viscosity determined at 250> In duPont #15 cup suggested by Lt. Wm. H,,Holst It would, therefore, appear that if necessary the amount of methyl ethyl ketone needed can be materially de creased or entirely eliminated, In the J-200 1C 7^12 formulation the solvent combina tion used is considerably slower than in the NCL. SS-193 type This is necessary because J 200 X-7012 Is applied at a con siderably le3s film thickness (10^1*5 mils) and for this .reseon must have a lesser degree of porosity,. The solvent combina tions recommended for this type are: DUP030001026 17- methyl ethyl ketone toluene methyl Isobutyl ketone ko 20 40 40 No02 blend is recommended for use where a high percentage of VYNS is used such as in J-200-X-7182 G - Application In the spray application of the NC& SS-195 nothing can be added here which is not already, covered In Manual OPl485 (Preliminary), However, for the J-200-X-7012 and J*200 X"7l82 the following recommendations are made0 Spray ing should be done, either at package viscosity or reduced slightly with a 1/1 mixture of toluene and methyl Isobutyl ketone- Although other types of spray equipment can undoubtedly be used, it is recommended that a De Vilbiss MBC gun equipped with a #70 or #76 cap and an E tip be usedo Pressure at the gun should be 75 pounds or greater and 20- >35 pounds oh the fluid. Under these conditions a non-porous 10 mil thick film can be laid down in 5"4 spray coats,. A minimum elapsed time of five minutes between coats is desirable.. 3o Adhesives One cf the main problems in developing the NGL SS-'193 system of packaging has been the development of a satisfactory adhesive for*adhering the film to the base of equipment to be packaged., A survey was made of potential candidates for this job which would give a better bond than Tygon TP-107A, the adhesive originally recommended,. It was found that adhesives such as "Gaytex" or "Pllobond" which are based on a phenol- formaldehyde resin modified butadiena/acrylonitrile copolymer give the best Initial bond and least thermoplasticity of any of the adhesives tested* Some of these adhesives were; Tygon TP-107A "Vinylite" VMCH "Vinylite" VMCH plasticized with Paraplex G -25 wVinyllten VMCH plasticized with methoxyglycol acetylrlcinoleate (5) k&55t a selfcuring "Butaoite* type (6) Gaytex 111 Pliobond C'-62"53* a duPont experimental cement similarto Gaytex DUP030001027 -18 Of these, Noso 6, 7 and 8 were best in initial properties In addition, it was also found that initial bond strengths and resistance to loosening of the bond under a load at elevated temperatures can be improved by {1) using Estic #L|4 oil in place of Rustban 60J and (2) replacing 10# of the resin in NQL SS-193 with VMCH resin,, The following table gives the strength required to pull a one inch strip of (1) NOL SS-193, (2) Estic #44 oil modification of NOL SS-193 (2098-179"!) and (3) Estic #44 oil modification with 10# of resin replaced by VMCH (2098-171-1) from steel coated with the following adhesives: {The adhesives were brushed on lptl2w steel panels which had been sanded to a smooth surface and allowed to dry one hour* The strippable coatings were then sprayed over the adhesive to a film thick ness of 30 mils and the system then allowed to age at room temperature+ 5*}for one week before tests were made*} NOL SS-193 over Pliobond Gaytex C-6253 VMCH VMCH/Paraplex G-.-25 Adhesion In Grama .. I3B5--------------- 1350 425 too low to be measured too low to be measured 2098-179-<1 over Pliobond Gaytex C~62~53 VMCH, VM5H/Faraplex G-25 1670 1735 1015 54-0 955 2098-171~1 over Pliobond * Gaytex C-62 >53 VMCH VJCH/paraplex G--25 1675 1900 1135 800 2250 However, thermoplasticity tests made at a 180 pull with a dead load of 1/2 pound per inch width indicate that Pliobond and Gaytex have the best heat resistance and this is especially true tinder the 2098-179! 2098-171-1 modifica- tlons of NOL SS-193o Check tests on NOL SS-193 and 2098-179l over Gaytex and Pliobond made at a 45 P^ll which more closely simulate the most severe conditions to be met in service gave the fol lowing resultso In the following tables 9-1/2 inohes is the maximum distance the film can be stripped* DUP030001028 "191 iSo^p,, NOL SS-193 over Pliobond in J+5 min-, Gaytex 9^5 in,, In 1 hr0 2098179~1 over. Pliobond 15 in0 in 2 hrSo Gaytex Ool in* In 2 hrs.. idQF o Yft Inin 75 in,, 9 5 in* in 5 hr8 o 95 ino in JO hrso 0,,2 in. in 30 krsi ii;0op., "Join-' in i}.8 hrs 95 in., in 1|8 hrs , 602 in0 in 148 hrso 0.8 in, in I4S hr b <> These teats indicate that the use of Rustban 603 in formulation NGL SS-193 does not give the heat resistant bonds with "Gaytex or Pliobond1* as are obtained with Estic #44. oil, and that Pliobond is inferior'to Gaytex0 However, because these testa may be considerably more severe than will be en countered in actual service and because these results have not been correlated with those obtained in the field, the apparent weakness of these adhesives in resistance to a dead load pull at elevated temperatures, may not be as serious as it would ap pear from the tests As for the differences encountered between Gaytex and Pliobond which are supposedly identical in composi tion, batch to batch variation of the adhesive may be the answer,. By changing the oil in NOL SS193 from Rustban 603 to Estic #44, an improvement in heat resistance of the bonds can undoubtedly be obtained but this must be balanced against a sligjht decrease in corrosion resistance,, The systemslisted in the above table are now being exposed outdoors with a dead load of 1/2 pound per inch at a 45* puli' in order to determine their resistance to flow under constant load at summer temperatures, Some preliminary experiments to develop a self-curing adhesive in order to improve the heat resistance of the bonds have'not met with any success as yet0 These adhesives were based on Vinylite/Hycar combinations and were two package compositions with one of the solutions containing the vulean izatlon agent and the other containing an ultra accelerator such as a butyraldehyde/monobutylamine condensation product , liu vrebblng Agents or Lacquers A high^spot investigation has been made to evaluate the merits of other film formers as webbing agents or webbing lacquers having working properties equal to or better than Solution A (NOL SS-193)* the webbing agent developed at the Naval Ordnance Laboratory,, Silver Spring, Md,, for use in con junction with Solution B (NOL SS*l93)n DUP030001029 -20- Among the candidates examined were: polyvinyl butyral polystyrene polyvinyl acetate n-butyl isobutyl methacrylate polyvinyl pyridine methyl methacrylate Styraloy (Dow Chemical Co.) None of the above polymers produced a lacquer with as satisfactory webbing properties as Solution Ac However? a lacquer based on a mixture of polyvinyl butyral and poly vinyl acetate had webbing characteristics which approach that of Solution A, and might be considered . secondary alternate composition-. This lacquer has the following composition: 2098-282 -2 polyvinyl butyral polyvinyl acetate Rustban 603 ethyl alcohol acetone toluene aliphatic hydrocarbon (65 405*0 .) 9*5# Ho 7 2U8 57*7 16 *0 'lOoij. 18,9 i$6:w CGMiRMW S/30/k5 DUP030001030 DUP030001031 II DUP030001032 wmmm t i i DUP030001033 DUP030001034