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METALS DIVISION To (Name) Mr. R. E. Byrne, Jr. Division UCC-Metals Division Location Niagara Falls, NY Copy to Messrs. F. J. McCarthy J. L. Myers File P. 0. BOX 579 -4625 ROYAL AVE., NIAGARA FALLS, fJEWYORK U Date Originating Dept. May 7, 1979 "Calidria" Asbestos Answering letter date Subject Possible Montello Patent on Oil-Wetted Asbestos Attached is the patent in Formation from Montello. I don't see anything in the three patents 1 is Fed that bears closely on the Montello invention. The question in my mind is not so much specific prior patent art, but whether a person with a reasonable technical knowledge of chemistry and drilling mud technology, i.e. skilled in the art, could have assembled the elements described. The invention has four limitations imposed in the choice of the oil plus the use of a surfactant. On this basis it seems to rne that a reasonable application could be written for a patent based on a combination of five ingred ients particularly if very critical ranges can be defined for several or all of them. Such a patent would obviously be quite narrow in scope. In this connection, it must be remembered that a patent covering only ''Calidria" asbestos has a far more limited commercial scope than one covering all short-fiber chrysotile, regardless of source. yJ /). H. B. Rhodes HBRrdal Attachment 6106 EAST 32ND PLACE TULSA, OKLAHOMA 74135 (918) 665-1170 / TWX 910-845-2396 April 24, 1979 RECEIVED APR a 7 797g -SSSSSf, Dr. Harry Rhodes Union Carbide Corporation Metals Division P. 0. Box 579 Niagara Falls, New York 14302 Dear Harry: Sorry for the delay in getting these off to you. Frankly, it slipped my mind until my talk with Bob Byi'rie earlier today. We are moving rapidly toward our first manufacturing run of any size on the oil wet product. Should have 2,500 to 3,000 bags ready by mid-May. All tests so far leave us optimistic about the possiblity of generating some very low TWA's. Of course if there is any way of securing some kind of pro prietary coverage for the product, this should be done. Enc. (5) cc: Harry Wyatt Allen Johnson To Whom It May-Concern: Asbestos has long been known to be an effective viscosifier in aqueous drilling fluids. It is also known to be mere effective than other viscosfiers in aqueous systems containing salt and/or other contaminants. Modified forms of asbestos are also used as viscosifiers in oil base and invert systems. The problem in the recent past has been the adoption of regulations governing the use of asbestos where any airborne fibers are emitted. This regulation has prevented many companies from using asbestos, although it is generally agreed that asbestos is the most economical viscosifier in aqueous systems, especially those containing salt and/or other contaminants. In order to eliminate this problem, a number of different approaches have been taken, including different forms of the asbestos. These forms have included plain ground, pellets, cracked pellets, and water-wet. The above forms have not eliminated the problem of airborne fiber emissions. The approach taken here was to coat the granular pellet with an oil like substance thereby reducing the possibility of any airborne fiber / emissions. The oil used must have the following characteristics: 1. Non-fluorescing 2. Bio-degradability 3. Low KB number 4. Must not adversely affect the yield of the asbestos Along with the oil, a surfactant is added in very small quanities. The purpose of the surfactant in the oil is: 1. To increase the penetration of the oil into the pellets. Law OrrCES P. A.Head, Johnson & Chafin, Patent and Trademark Attorneys JAMES R. HEAD PAUL H. JOHNSON JAMES H. CHAPIN RONALD H. EVANS PATENT AGENTS DR. DANIEL SILVERMAN MILORED K. FLOWERS May 18, 1978 212 BEACON BLDG. Tulsa,Oklahoma 7-4103 (916) S6A-AIB7 Montello 6106 East 32nd Place Tulsa, OK 74105 Attention: Mr. Harry Wyatt, Vice-President Re: Aqueous Viscosifier - Our File 78-140 Dear Mr. Wyatt: Pursuant to your request, we have conducted a preliminary patentability search in the United States Patent & Trademark Office relating to an asbestos viscosifier which is specifically designed to eliminate the problems of air borne fiber emissions and the following patents were found as a result of that search: Otouma et al Heron Xanthos et al 3,967,043 3,660,148 3,965,284 (1976) (1972) (1976) Very briefly, the patent to Otouma et al teaches a dust proof asbestos which is coated with a water soluable film and is further impregnated by a water-insoluable compound. The patent to Heron teaches the coating of asbestos cloth and other materials with polymeric coating, again for the purpose of reducing airborne fibers and dust content. The patent to Xanthos et al teaches the encapsulating of chrysotile asbestos. The above three patents were the closest art found in six subclasses of four separate classes of the search. Mr. Harry Wyatt May 18, 1978 Page 2 Although we are usually able to uncover the most pertinent prior art, you should be advised that a preliminary patentability search of this nature is not by any means an exhaustive search. Further, pertinent and prior art may not have been uncovered for various reasons including patents missing from the search room files and actual misclassification of patents. The cost of the search often renders it impractical to cover foreign art and publications which could prevent the issuance of a United States patent. Similarly, by law, we are unable to look at pending applications which could ultimately prevent the issuance of a patent. Although we did not find a specific oil and surfactant coating for asbestos material, I feel that you should study the enclosed patents before making a decision as to whether or not to incur- the expense of filing and prosecuting a patent application on your invention. After you have had an opportunity to make your decision, if you wish a patent application prepared I feel we should probably get together and discuss the process used to manufacture the viscosifier product. In the meantime, if you have any questions, feel free to contact me at your convenience. JHC:ms Enclosures United States Patent im Otouma ct al. 'nl 3,967,043 I4-Sl June 29, 1976 1541 ASBESTOS articles having DL'STI'ROOF PROPERTIES 3.542.706 11/1970 Columbus ct ul..................... 260/14 3.660,148 5/1972 Heron........................... 117/126 AB 1751 Inventors: Takashi Otouma, Yokohama; Micltio Nakamura, Odawara, both of Japan Primary Examiner--Ronald H. Smith Assistant Examiner--Evar, K. Lawrence Attorney, Ayenl, or Firm--Browdy and Ncimark 1731 Assignee: Nippon Asbestos Company, Ltd., Tokyo. Japan |22) Filed: Jan. 3, 1974 |2I1 Appl. No : 430,590 1301 Foreign Application Priority Data Mar. 26. 1973 Japan................................ 48-34299 1521 U.S. Cl..................................428/443; 428/524 1511 Int. Cl.1.......................................... B32B 19/02 1581 Field of Search...... 117/126 AB. 62.2, DIG. 3. 117/126 AO; 428/443, 271. 290. 375; 427/340, 341.342; 260/14 1561 941.605 1,111,286 2.190.672 2.249.514 2.318.560 2.534.818 2.774.687 3.415.674 References Cited UNITED STATES PATENTS 11/1909 9/1914 2/1940 7/1941 5/1943 12/1950 12/1956 12/1968 Back land...................... 117/161L Aylswurth......................... 117/161 L Meharg.......................... 1 17/DIG. 3 Berg cl al.......................... 117/139 X Ripper........................... I 17/126 AB Holmyd cl al................. I 17/126 AB Nnttchnhm ct al......... 1)7/161 t. X Voisincl................... 1I7/I26ABX 1571 ABSTRACT A method of preparing asbestos articles to exhibit dustproof effects in secondary processing without deg radation of the inherent properties of the asbestos arti cles comprises the step of immersing the asbestos arti cle in a treating agent comprising formaldehyde, a water-soluble organic compound capable of reacting with formaldehyde to form a water-insoluble com pound under weakly alkaline conditions in an atmo sphere maintained at a high temperature and a high humidity, a plaslici/cr, and a water-soluble macromolecular substance having film forming properties, and the steps of infusing the asbestos article with a weakly alkaline solution ami fust reacting the asbestos article in an atmosphere maintained at a high temperature and high humidity, and subsequently heat treating the resulting pioduct to obtain the final product. The final product is impregnated in the interior substrate thereof by 0.5 to 10 wt.'/c of the water-insoluble com.pound, has a surface layer of 0.(>4 to 0.09 wt.Vr of a film of the water-soluble m;icronio!ecular substance, and has 1.5-30 wt.% op a polyhydric alcohol plastici/.er. 2 Claims, 1 Drawing Figure U.S. latent June 29, 1976 3,967,043 3,967,043 12 ASBESTOS AHTICLES HAVING DUSTI'HOOF PROPERTIES DETAILED DESCRIPTION The product formed in accordance with the method of this invention is hereinafter referred to as the "com FIELD OF THE INVENTION 5 plete product." Because the treating agent used in the The present invention relates to a method of prepar present invention is impregnated through the entire ing and treating asbestos articles to exhibit dustproof staring asbestos article and close adhesion and bond properties in secondary processing, particularly spun ing among asbestos fibers in the asbestos article is ob and woven asbestos articles, by treating such articles with a treating agent without degradation of the inher ent asbestos properties of the articles. 10 tained in the aging and heat treatment steps, the amounts of each ingredient in the treating agent is defined based on the weight of the dried complete product. BACKGROUND OF THE INVENTION The complete product comprises 1.5 to 30 wt.% of Emulsions, dispersions or solutions containing mac- 15 said polyhydric alcohol or other high-molecular-weight alcohol, 0.04 to 0.09 wt.% of the water-soluble macro romolecular substances have heretofore been used for molccular substance having film-forming properties imparting dustproof properties to asbestos articles. which is uniformly distributed through the surface According to conventional techniques, such treating layer, and 0.5 to 10 wt.% of the water-insoluble com agents are impregnated into the interior substrate and pound formed during (he heat treatment and aging /or onto the surface portions of an asbestos article and 20 steps which is distributed through the interior of the then the dispersion medium or solvent is removed bv complete product. The treating agent to be used in this drying, thereby leaving a film of the macromolccular inventiuu may further comprise methanol as a stabilizer substance contained in the treating agent. Since in the for an aqueous solution of formaldehyde. If the amount secondary processing of asbestos articles they are sub of polyhydric alcohol or other high-inoleculai-weight jected to cutting and other processing operations, it is 25 alcohol, the plasticizer, is less than 1.5 wt.%, plasticiz essential that the dustproof properties be imparted ing effects in the aslsestos article cannot be obtained, uniformly to not only the surface portions but also the and if the amount of the plasticizer exceeds 30 wt.%, interior substrate of asbestos articles. However, in con the jrilasticizer, a liquid substance, will ooze out when ventional techniques, the dispersed substance or solute tends to gather on the surface portions of an asbestos 30 the asbestos article is pressed by fingers or the like. If the amount of the water-soluble macromolccular sub article at the drying step, thus the distribution density is stance to be used as the film-forming substance is less frequently lower in the interior substrate portion of the article. Consequently, optimal dustproof effects cannot be obtained using conventional techniques. 35 than 0.04 wt.%, the resulting dust-proof effects are too low, and if the amount of this substance exceeds 0.09 wt.%, the surface layer of the asbestos article becomes too readily combustible. In this invention, the content BRIEF SUMMARY OF THE INVENTION of the water-insoluble substance formed by the reac This invention provides a method which overcomes tion between the water soluble organic compound and formaldehyde is limited to a range of from 0.5 to 10 the above mentioned defects in conventional tech wt.% because at a content below 0.05 wt.% the dust- niques by imparting dustproof properties uniformly to 40 proof effects are too low and at a content exceeding 10 not only the surface portions but also the interior sub wt.% the complete product becomes too hard to work strate portion of an asbestos article without the degra in the subsequent secondary processing. dation of its inherent asbestos properties. The treating Some examples of treating agents employed in the agent used in this invention is one prepared by forming method of this invention 2re set forth below: a mixture of formaldehyde with a water-soluble organic 45 compound capable of both being aged under weakly Example I alkaline conditions in an atmosphere maintained at a Melamine ( 13% aqueous solution) high temperature and a high humidity and reacting with Formaldehyde (20% aqueous solution) Glycerin plasticizer formaldehyde to form a water-insoluble compound, Polyethyleneoxide water-soluble adding a plasticizer such as a polyhydric alcohol or any 50 macromolecular substance (0.5% aqueous solution) other liquid alcohol having a high molecular weight, Methanol and finally incorporating a water-soluble macromolec- Total 50 parts 50 parts 3 parts 10 parts \ part H4 parts ular substance having film-forming properties into the Example 2 resulting mixture. An asbestos article to be treated, 55 Urea | It)?* aqueous solution) Formaldehyde (20% aqueous solution) hereinafter referred to as a "starting article," such as a Ethylene gUcol plasticizer spun or woven article of asbestos in the form of cloth, Polyvinyl alcohol water-soluble macromolecular substance tape, rope or the like, is immersed in this treating agent t0.5% aqueouv solution) in order to impregnate the starting article with the Methanol Total treating agent. Then the resulting product is first aged 60 with a weakly alkaline substance in an atmosphere Example 3 Urea (259 aqueous volution) maintained at a high temperature ar.d a high humidity, Formaldehyde (38% aqueous solution) 50 parts 50 parts 5 parts 10 parts 2 parts )|? parts 50 parts 50 parts and subsequently subjected to heat treatment and dried. Glycerin plasticiser Poly clhylencoside water soluble marromnlccular substance BRIEF DESCRIPTION OF THE DRAWING 65 Ctt uqucou* solution) Mvihanol 'total 5 parts 10 parts 4 parts l|9 parts FICi. 1 is a schematic diagram of an apparatus em ployed in carrying out the method of this invention. F.samnle 4 Pncnol ( 10% aqueous solution) 40 parts 3,967,043 3 continued Formaldehyde (20*3.tqucou* xolutrnn) Glycerin ptaxiici/er 40 parts 40 parts 4 or methyl cellulose forms a film the surface layer of the starting article at the drying step and thus exhibits dust-proof effects. Furthermore, since the polyhydric Methyl cellulose waleresoluble macr<*m*>Iccul.ir plasticizer (1% aqueous solution) Methanol Toul 10 parts 2 parts 132 parts or other high-molecular-weight alcohol such as glyc 5 erin or ethylene glycol is distributed through the inter ior of the starting article as a liquid plasticizer, despite the above-m- oned bonding activity and film-forming Psample 3 Aqueous solution of phenol prepolymer (average molecular weight -- 200; concentration -- 60% Formaldehyde (3% aqueous solution Glycerin plasticizer Polycthylcneoxidc water-soluble macromolccular substance (0.5% aqueous solution) Water Total I part I part 3 parts 10 parts 83 parts 100 parts activity brou...; about in the interior and the surface layers of the asbestos article, the flexibility is not lost in 10 the complete product. In order to know the duslproof effects of the com plete product made in accordance with this invention, tests were conducted in the following manner using products made with the treating agents of the above IS Examples 1 to 5. A film filter is connected to a suction pump and the sucking rate is adjusted to 200 cc/min. The method of the present invention can be illus The sample is cut with scissors at the same height as the trated with reference to FIG. 1; guide rollers of varying filler and about 30 cm from the filter. Asbestos fiber diameters are connoted by reference number 8. A starling article 1 is passed through a treating bath 2 20 dust formed by the cutting step is collected by the filter. The collected dust particles are fixed on the filter film containing treating agent 3 to impregnate the starting by use of a fixing agent, and after the filter film is made article with the treating agent. The impregnated article transparent by use of a chemical, the filter film is ob is forwarded through squeeze rolls 4 and 5 where ex served under a phase-contrast microscope. The num cess treating agent is removed so that the weight of the impregnated article is 2.1 to 2.2 times the weight of the 25 ber of particles having a length gi eater than 5 ,u is counted and the number of asbestos dust particles per starting article. Then, the impregnated article is cc of air is calculated. Results are shown in the follow brushed by means of brushing rolls 6 and 7 to infuse a ing Table: water-soluble alkaline component through the asbestos article and into the treating agent impregnated in the JO starting asbestos article in order to attain the weakly alkaline conditions (pH 8--11) necessary for the reac tion of the reactive substances in the treating agent. Table I N-iml'Cf of asl'rM is ck-.xt paf'idox per cc of Air ikxi. Inlay Appearance During this brushing treatment, the impregnated asbes Untreated A Hide tos article is also squeezed by the brushing rolls so that 35 Product of bum;)!* 1 the weight of the impregnated article is about 2 times Product of Example 2 Product of Example 3 the weight of the starting article. Then, the aging step is conducted for 15 to 20 minutes in an aging tank 9 filled Product of Example 4 with high humidity conditions (R.H. 20%--100%) at Product of Example 3 70C-- I00C. The article coming from the aging tank is 40 heat-treated and dried in a drying furnace 10 main 3D pood good 1.2 good good 1.3 food gotnl 0.9 slightly slightly inferior colored 1.2 slightly colored 1.3 good . good tained at about 70C--150C. This results in a complete As is indicated by the results from the foregoing product which comprises 1.5 to 30 wi.% of the poly- Table, in the complete product of this invention, sur hydric alcohol or other high molecular-weight alcohol faces of interior asbestos fibers are covered with the as the plasticizer, 0.04 to 0.09 wt.% of the water-solu 45 water-soluble resinous compound and these fibers arc ble macromolecular substance having film-forming bonded tightlv to one another by such water-insoluble properties uniformly distributed in the surface layer resinous compound. Furthermore, a film is formed on and 0.05 to 10 wt;% of the water-insoluble compound the surface layer of the asbestos article. Accordingly, in distributed through the interior of the complete prod the complete product of this invention, the dustproof uct and formed by the above aging and heat treatment 50 effects are attained in not only the interior but also the steps. In the foregoing example the brushing treatment outer portions and these effects are very high. More is adapted to attain weakly alkaline conditions, but over, although the interior and outer portions of the means for attaining weakly alkaline conditions are not asbestos article are in the coaled state, flexibility is limited to a brushing step and it is possible to add an imparted to the complete product by the presence of alkaline substance such as aqueous ammonia or a dilute 55 the plasticizer and therefore, the inherent flexibility of solution of sodium hydroxide by some other suitable the asbestos article is not lost in the complete product means. of this invention. . The water-soluble organic substance such as mela The foregoing description of this invention will so mine. urea, phenol and phenol prepolymer used in the fully reveal the general nature of the invention that above examples 1-5 is fixed and bonded to the surface Ml others can, by applying current knowledge, readily of the asbestos fibers in the aging tank 9 and reacts with modify such invention and/or vary it without departing formaldehyde to form a water-insoluble resinous com from the generic concept, and. therefore, such varia pound. This reaction proceeds and is completed in the tions and modifications should and are intended to be drying furnace 10. The water-insoluble compound comprehended within the meaning and range of equiv formed by this reaction acts as a dust-proofing binder 65 alents of the disclosed invention. It is lo be understood bonding asbestos fibers to one another in the interior of that the phraseology or terminology emplojcd herein is the asbestos article. The water-soluble macromolecular for the purposes of description and not of limitation. substance such as polyethylencoxide, polyvinyl alcohol What is claimed is: ->,2 0 / ,UH0 56 1. An asbestos product which exhibits dusiproof cf- said asbestos product of a film of a w ater-soluble mne- , feels comprising an asbestos article impregnated in the rumolecular substance, said asbestos product having interior substrate thereof by the reaction product of 1.5 - 30wt. *3 based on the weight of the asbestos prod formaldehyde and a water-soluble organic compound reacted therewith to form a water-insoluble compound under weakly alkaline conditions in an atmosphere 5 uct of a polyhydric alcohol plasticizer therein. 2. The asbestos product in accordance with claim 1 maintained at a high temperature and a high humidity, wherein said water-soluble organic compound is mela said reaction product being present in an amount of mine, urea, phenol or phenol prepolymer, and said r 0.05 to 10 wt.^ based on the total weight of the asbes water-soluble macromolecular substance is polye- tos product, said asbestos product having a surface 10 thylcncoxide, polyvinyl alcohol or methyl cellulose. layer of 0.04 to 0.09 wt.Sr based on the weight of the IS 20 25 30 35 40 45 50 55 60 65 --i 3 b:> 2 > j *t 6 7T *4 1 ^y oiiUC . :. V---------^>/ vt *. *> H orcr: Patent ;: j M~v :. i r?2 [5*] TREATMENT OF ASBESTOS [72] Inven'r-: Ccrdon F. Heron, Rochdale. England [73] Assigns:: Turner Brothers Asbectcs Company Lirrulcd, Manchester. England [22] Filed: Jar.. 2. T>70 [2!] Appl.Nc.: 1,635 [3C] Fcrei-n Application Priority T sta Jcr- 10. 190? Crest Britain........................... 1,579/69 [52] C.S.C!...........117. a2 AE, 1I7M6! CC. 117/161 I'D. 117/162. i-.-2/155. It !/'2 [5'] Int.C!................................P371. I'JMI.psph 19;.;t'j'sj risiuorr-tsrc:..............i\ir: : ab. :e-: vt>. i6i uc. 1.7/162; lv.2J.l-5i 101.92 [56] F.e'er-srcs Cit'd UNITED STATES PATENTS 2.264.15S 11/1941 Clark.............. .................. 117/126 AE 2.563.144 ' 9/]951 Crerter r: si.'..:...... ........... i 17/!26 AS FOREIGN PATENTS OR A":. /CATIONS 591,327 1/1560 Crr.u/s.................................1 ',7/!26 AB Primary Zxcrr.incr--V-'.'iiarr. IN h'.artir Assiatc::; F.xmir.e?--D. Ccr.-.r. Attorney--Suyhrue. F.c:r. ell. Mica. Eire, .v: Maepea'.: [57] ..35T.-.ACT The invertirr crrrrn.-.--; r.-tas cloth srd ether asbestos products to r;.jthe ass: e:-..red by durir.; hardline and use. 77 dear t.y d:-" 'ting a sr.-.si' atr.at r.* of poivner:; retie:.r thrr. jy.cu: '.re p-rvi-c: to : ere ties fibers to or.; another . 1 : in th~ - . c;'.:.-: t ;ccet the dur.iiat-it ess'-cti.i"!. h . I. 71.-: rrv t*rrd m;:' r - con sists in imp: oyr,N- . . .. .v v .,h : .tsn.s i.r or suspension cf lh> - i. :c r. ater.a' ;i;d re:...i.:p water. 6Ci . =. M. " - PATENTED HAT 2 IS72 SHEET 1 OF 2 3.660,148 FIG. I FIG. 2 BY INVENTOR GORDON F. HERON ATTORNEYS Dl AIMEOKAYZ 137? SHEET 2 OF 2 3.660,148 zo D'g. 4. GORDON F. HERON by Z?Zi4A\ J sM*efiaajg Attorneys 3,660,148 12 TREATMENT OF ASBESTOS BACKGROUND OF THE INVENTION asbestos product throughout with a dispersion, emulsion or solution of the polymeric material, and removing the continu ous phase of the dispersion or emulsion or the solvent of the 1. Field of the Invention Thu invention relatet to the treatment of asbestos products. 5 solution to leave polymer particles adherent to and bonding together at least the majority of the fibers at points of contact 2. Description of the Prior Art with other fibers. On the other hand, spreading a melt of the In recent yean the risk of contraction of asbestosis by peo polymeric material on asbestos cloth is of no value, as it mere ple who make or handle asbestos products has been increas ly proofs the cloth. ingly appreciated. This risk arises when asbestos dust is present in the atmosphere. Dust control is usually achieved in 10 DETAILED DESCRIPTION OF THE INVENTION manufacturing processes by the use of ventilation, or by en While a solution gives maximum penetration and bonding of closing or shielding machinery, but the users of the manufac the asbestos, the most suitable polymeric materials are not tured products frequently work in unprotected atmospheres. water-soluble, and the use of organic solvents leads to For example, asbestos cloth used as insulation is often tom by 15 problems in solvent recovery. Preferably, therefore, the the installers, and asbestos clothing is often roughly handled. polymeric material is applied in the form an aqueous disper- Then short fibers fluff and fibrous particles are given off as sion or emulsion. A particularly advantageous process com dust into the atmosphere. prises immersing the asbestos product in an aqueous emulsion The suppression of asbestos dust is accordingly an acute ot dispersion, e.g. by passing it through a bath of the emulsion problem. Coating the product is an obvious approach, but has 20 or dispersion, mechanically expressing water from the materi not proved successful. el. e.g. by passing it between two rolls, and then drying it, e.g. The most important requirements for the majority of by passing it through a dryer. To ensiiie uniform distribution asbestos products in normal use are that the products should of the polymeric material in the asbestos product, its concen give rise to the minimum of dustiness in normal handling (not tration in the dispersion or emulsion should be low . preferably necessarily tearing), that the flexibility and handling charac 25 no more than 5 percent by weight and better still no more than teristics of the product should not be substantially impaired, 2 percent. and that the product should be compatible with materials sub What is required is that the pick-up of the polymeric materi sequently applied to it, such as resin, rubber or paint. In short, al shall be from 0 1 to 5 percent weight of the asbestos the product, though treated to suppress dust, should not lose prodqct, and preferably from 0.5 to 3 petcent by weight, and any of its natural characteristics other than that of giving off 30 the concentration of the polymeric material, the duration of dust. the immersion, the amount of water expressed, and the nature The most important asbestos products which it is desirable of the cloth or other asbestos product must be correlated to to treat for dust suppression are asbestos cloth of all kinds, give the desired pick-up. which normally contain a small proportion (say 10 percent) of Asbestos slivers or yarn may be impregnated by passage cotton or other organic fibers Other materials advantageously 35 over a damping roller which dips inlo a bath of a dispersion or treated include slivers, yarns, tapes and rope. emulsion; in this case the concentration of the polymeric A solution of the problem proposed some thirty years ago material may be higher, say up to 10 percent. involved brushing a synthetic resin diluted with acetone onto Polymeric materials of very different chemical composi the outside of a garment of asbestos cloth and, after evapora tions have been found to give satisfactory results, though same tion of the acetone, baking the garment to toughen the resin. 40 such as polyvinyl acetate must be plasticized if they are to However, the application of a surface layer to asbestos cloth have the required extension to break without which satisfacto impairs the handle and flexibility of the cloth and in practice ry results are not obtained. Suitable polymeric materials with docs not solve the problem, because dust in the interior of the their approximate percentage elongations at break include cloth is still liable to escape, for example when the cloth is lorn. As far as we are aware this old process has never come 45 polyvinyl acetate plasticized with 20 percent dibutyl phthalaic (<(50 percent), terpolymers of vinyl acetate, unsaturated acid into use in practice. and vinyl caprale (300 percent), copolymers of vinyl acetate To proof asbestos cloth with rubber or other material is also and 25% 2-ethyl-hexyl-acrylate (320 percent), plasticized known, but this is no remedy, as the cloth is completely polyvinyl chloride (50 percent), copolymers of vinyl acetate changed in handle, flexibility and appearance by the proofing. 50 and an ucrylate and copolymers of styrene and an acrylate, SUMMARY OF THE INVENTION (which are too soft to test for extension), natural rubber latex (2,000 percent), styrene-butadiene rubber latex (2,000 per 1 have surprisingly found that asbestos cloth and other cent) and neoprene (1,500 percent). In contrast unplasticiscd products can be rendered substantially less dusty without es polyvinyl acetate (8 percent) renders the product stiff and sential modification of any other property of the cloth or other 55 harsh to handle, os do emulsions of polystyrene (3 percent) material if a suitable polymeric material is so introduced into and emulsioms of phenol-formaldehyde resins (3 percent). the asbestos product as to bond as many as possible of the These polymeric materials so modify properties of the product fibers to one another. as to be of no value. To be suitable, the polymeric materia] must have two essen In the drawings, tial properties. First, it must possess the ability to bond the 60 FIGS. 1 and 2 are photomicrographs of. respectively, un fibers in the asbestos product, and a suitable criterion of this is treated asbestos cloth Bnd asbestos doth treated according to film-forming ability, that is to say ability to form a coherent the invention. film on drying from solution, emulsion or dispersion. Second FIGS. 3 and 4 diagrammatically show two ways by which and most important, it must be flexible; a suitable criterion of asbestos products can be treated according to the invention. flexibility is the extension at break of the materia) under the 65 Referring to FIG. 3, a roll of asbestos cloth 1 is unwound to A.S.T.M. tensile test D 882-611 and under this lest the pass round a roller 2 in a bath 3 containing an emulsion or polymeric materia) must have an extension to break of at least dispersion of the polymer, and leaves Ihe bath to pass between 10 percent, and preferably at least 50 percent. Ad rollers 4 and 5 which express liquid from it, this liquid vantageously the polymeric material is thermoplastic or dropping back into the bath. The impregnated cloth then elastomeric. 70 travels through a dryer 6, which is essentially formed by a According to the invention at least the majority of the fibers housing for four cylinders 7 internally steam-heated to and in an asbestos product are bonded by particles of such a from which the doth is guided by rollers 8. polymeric material distributed throughout the asbestos Some examples of the treatment of different asbestos dothi product in an amount of from 0.1 to 5 percent by weight of the in apparatus such as that diagrammatically shown in FIG. 3 product. This distribution can be effected by impregnating the 75 will now be given. 3,660,148 34 EXAMPLE 1 Since dust may be produced by normal handling, which in cludes chafing and flexing, or by tearing, tests have been A general purpose asbestos cloth, weighing 28 ounces per devised to enable comparisons to be made. The number of square yard with a plain weave was passed at 80 feel per fibers in air can l>c measured both by a Royeo electro-optical minute through an emulsion of a copolymer of vinyl acetate and maleic ester containing 1.7 percent solids by weight. The amount of liquid left in the cloth after passing through the rol lers 4 and 5 was 45 percent by weight of the cloth. The cloth emerged dry from the dryer 6 and contained 0.7 percent dry 5 particle counter, and by collecting the fibers on a membrane filler an;: rouming them under an optical microscope. In chaf ing tes -- -ample of cloth is repeatedly drawn through a rightangle across the edge of a metal plate inside a box through which air flows, and the fibers carried out of the box 8re as polymer by weight. The suppression of dust and the general handling characteristics were both excellent. 10 sessed. The results can be expressed as fibrous particles per cc of air (p/cc). In the tearing tests a mechanism in the same box EXAMPLES is externally operated to tear cloth. The results of such tests on both the untreated and the un A further roll of the same cloth as in Example 1 was treated in the same way by passage through a bath of an emulsion of 15 treated cloths of Examples 1,2,5,6 and 8 are given below. mcthacrylic ester homopolymer. The pick-up of the polymer was 0.7 percent. The dust suppression was excellent, but the handle was not quite so good. Cloth Chafing Text p/cc Royeo Tearing Teit p/cc Royeo EXAMPLE 3 20 An asbestos cloth weighing 78 ounces per square yard with a twill weave, normally used for insulating lagging, was treated exactly as in Example I. but the amount of liquid left in the cloth after passing through the rollers 4 and 5 was 50 percent 25 by weight. The pick-up was 0.8 percent. The results were as good as in Example 1. EXAMPLE 4 Untreated cloth ol Examples 1 and 2 Example 1 Example 2 Example 8 Untreated cloth of Example* 3 and 6 Example 3 Example 6 7.8 0 17 02 0.25 27 0 22 0 25 53 5 13.1 90 14 0 46 1 11.5 120 Equally good results were obtained on the cloth used in Ex 30 ample 3 when the emulsion of the copolymer was replaced be natural rubber latex.. As itn indicatum of ihe reduction of dust in practice. specimens of the iiulrcntt-d cloth of Example 1, Ihe cloth as (i rated in that crumple, nod th: same cloth treated with natu- EXAMPLES 35 r.d lubber l.tlex were torn and then fitted round a steam pipe. A cloth weighing 36 ounces per square yard with a (.'lain Samples of the air were taken dr.ring the tearing processes. weave was treated with a styrene-butadiene rubber latex, the and continuous ait samples; were taken during the fitting and pick-up being C.6 percent. The dust suppression and handle sevring of the cloth in position. The Table below shows the were both excellent. results obtained. EXAMPLE 6 40 The same cloth as in Example 5 was treated in the same way During During Fitting with an emulsion of a copolymer of styrene and an acrylic acid ester, the pick-up being again 0.8 percent by weight. The dust suppression was excellent, but the treated cloth, though 45 Cloth Tearing p/cc and Seeing p/cc satisfactory, was a little stiffer. Untreated Cloth 61 0 60 Cloth treated as EXAMPLE 7 The same cloth as in Example 1 was treated with an emul 50 in Example 1 Cloth treated with naluTj> rubber latex 8.6 60 22 2.3 sion of polyvinyl chloride plasticized with 15 percent tricresyl phosphate, the pick-up being 0.7 percent. The dust emission was much reduced, but the improvement was not as great as in That the treatment according to the invention does not in Example 1. terfere with post-treatments of the cloth is shown by a test in EXAMPLE 8 55 which untreated cloth of the kind used in Examples 5 and 6 and the same cloth treated with natural rubber latex according Example 1 was repeated with neoprene latex as the to the invention were proofed with rubber, and then pieces of polymeric material. The dust suppression was good, but the the proofed cloths were plied together under heat and pres product became stiffer and discoloured with age. so neoprene 60 sure. The resultant laminates were then tested for strength is most suitable only when the product is to be used shortly between th: plies by a peeling test. It was found that the after treatment. laminate produced from the cloth treated according to the in In contrast, when the cloth of Example 1 was treated with vention resisted peeling better than the laminate produced an emulsion of a phenolic resin of 2 percent concentration by from the untreated cloth. weight, with a pick-up of 1 percent, the dust suppression was 65 FIG. 4 diagrammalically shows the impregnation of asbestos poor and the cloth became excessively stiff and harsh. When sliver as it passes through a spinning frame. the same cloth was treated with an emulsion of unplasticised The asbestos sliver, shown at 9. passes between rollers 10 polyvinyl acetate to give a pick-up of 0.8 percent there was no and then over a damping roller 11 which dips into a bath 12 of significant improvement in dust emission, and the cloth was a dispersion or emulsion of the polymeric material and from unacceptably stiff and harsh. 70 this to a flyer frame package 13 shown purely diagrammati- A practical test for the emission of dust is "mark-off," that cajly. In passing from the bath to the package 13 the sliver ii to say the appearance of fibers on a dark cloth against which passes over a bat 14, the position of which determines the the product is rubbed. Untreated asbestos products leave nu angle of contact 0 between the damping rolier 11 and the par merous small fibers on the cloth, whereas products of Exam tially twisted sliver. The twist runs back from the package 13 ples I to 8 mark the cloth to a very much smaller extent. 75 to the rollers 10 with the result that the sliver is rotating while 3,660,148 56 in contact with the roller 11, the uniformity of impregnation Asbestos cloth according to the invention presents the addi being accordingly improved. tional advantages that it is of improved appearance and im The advantage obtained by-mean* of the invention is shown proved weave stability, and that when cut it frays less than by dust measurements made in the atmosphere close to a similar untreated cloth. spinning frame in which asbestos sliver was impregnated with 5 I claim: an emulsion of the copolymer of -x>Iyvinyl acetate and maleic 1. An asbestos product rendered substantially less dusty ester of 8 percent concentration, and also when more of the without essential modification of any other property by parti same untreated sliver passes to the frame. The pick-up of the cles of a film-forming polymeric materia] having an extension copolymer was 0.5 percent by weight of the sliver. The Royco to break of at least 50 percent, distributed throughout the measurement in p/cc was 1.0 for the untreated sliver but only 10 product in an amount of from 0.1 to 5 percent by weight of the 0.35 for the treated sliver. product and bonding at least the majority of the fibers at The yams spun in the frame were tested for dust emission by points of contact with other fibers. being wound from the spinning bobbins into cheeses in a box 2. The product of claim 1 in the form of a-'oestos cloth. of the kind used for the chafing and tearing tests. During the 3. A product according to claim 1 in which the polymeric winding, the Royco counts in p/cc air were 2.8 for the un- *5 material is a thermoplastic or elastomeric material. treated yam, but only 0.65 for the treated yam. Moreover, the 4. A product according to claim 1 in which the polymer par treated yam. except for the improvement in dust emission, ticles amount to from 0.5 to 3 percent by weight of the was essentially similar to the untreated yam. product. An important property of asbestos cloth is inflammability. 5. A product according to claim 1 in which the polymeric Since the process according to the invention introduces a material is a copolymer of vinyl acetate and maleic ester. combustible product into the cloth, it might be thought that 6. A product according to claim I in which the polymeric there would be an adverse effect on inflammability. In fact, material is natural rubber oi slyrciie-huladiene rubber. the difference is negligible. 25 30 35 40 45 50 55 60 65 70 75 ' T An 3965264 . United States Patent m'i Xanthos ct al. mi 3,965,284 (45! June 22, 1976 I-54 J CHEMICALLY OPENING CHKYSOTILE ASBESTOS AND ENCAPSULATING (75) Inventors: Marinos Xanthos; Raymond T. Woodhams, both of Toronto, - Canada [73] Assignee: Canadian Patents and Development Limited, Ottawa, Canada |22] Filed: Jan. 19, 1973 (21] Appl. No.: 325,149 ]30] Foreign Application Priority Data Jan. 27. 1972 Canada................................ 133336 |52] U.S. Cl................................. 428/404; 162/155; 427/221; 427/299; 427/340; 427/341; 428/407 (51] Int. Cl.1.......................................... B32B 17/00 [58] Field of Search.............. 117/126 AB, 126 AO, 117/100 S, 62.1,62.2; 162/155; 427/299, 221, 340, 341; 428/404, 407 (56] 2.609.313 2.940.892 3.409,499 3.410.751 3,519,591 3.535.150 References Cited UNITED STATES PATENTS 9/1952 1/1960 11/1968 11/1968 7/1970 10/1970 Fettcl........................... 117/126 All Fciglcyel al.......................... 162/155 Drcshcr el al........................ 162/155 Battista................................ 162/155 Bolger........................... U7/126AQ Lipsclt.............................. 117/100 S 3.5K2.46U 3,635.K79 3.721.637 6/1971 Lipsell................................. 162/155 1/1972 Uatr ct al.......................... I 17/100 S 3/1973 Schultz el al........................ 162/155 Primary Examiner--Ronald H. Smith Assistant Examiner--Dennis C. Konopacki Attorney, Agent, or Firm--Alan A. Thomson (57] ABSTRACT Chrysotilc asbestos is chemically opened into the indi vidual fibrils by soluble vinylic polymer polyelectroIvtcs containing carboxylic acid groups in aqueous me dia. Polyacrylic acids, polymethncrylic acids, maleic anhydride polymers and water-soluble copolymers thereof are preferred polyelectrolytcs and form stable colloidal dispersions. The polyelcctrolytes are neutral ized to alkaline pH with inntganic or organic bases, but preferably with basic vinylic monomers when complete encapsulation is dcsiied. By a further aspect of the invention the polyelectrolyte-coated fibrils in aqueous dispersion are encapsulated by copolynterization witlt (a) a basic vinylic comonomer (used for pH control) such as dimcthyiaminoethyl methacrylate, t-bntylaminoethyl methacrylate or a vinylpyridine; and (b) a lion-basic vinylic comonomer such as styrene, divinylhenzene, vinyl chloride or fluoride, vinyl acetalc, methyl methacrylate, ethyl acrylate, acrylonitrile, and mcthacrylonitrile. The encapsulated fibrils are ad vantageous for foiming reinforced composites includ ing laminates and foamed or cellular products. 13 Claims, 4 Drawing Figures U.S. Patent June 22, 1976 Sheet 1 of 3 3,965,284 FIG. I Polymerization of styrene in the presence of polynicthacry] ic arid neutralized with sodium hydroxide. A- '^C*. yvs; i '*9i Vi $ FIG. 2 Polymerization of styrene in the presence of a copolymer of styrene -acrylic acid neutralized with ammonia. U.S. Patent June 22, 1976 Sheet 2 of 3 3,965,284 FIG. 3 Electron micrograph showing completely coated Chryaotile fibrils. Copolymerization of styrene/dimethylaminoethyl methacrylate (3/l) in the presence of polyacrylic acid. 6,340x. U.S. Patent June 22, 1976 Sheet 3 of 3 3,965,284 Electron microcraph showing completely coated chvysotilc fibrils. Copolyr.icrization of methyl methacrylate/ dimethylarainocthyl methacrylate (3/1) in the presence of polyacrylic acid. 7 940x. ritfi ^ 3,965,284 12 good strength after drying to remove excess water. The CHEMICALLY Ol'FWNG CHRYSOTILE dispersion may be spun through an orifice into a ASBESTOS AND ENCAPSULATING coagulaiinng medium such as for example an organic liquid, an aqueous solution of alkaline earth metal ions The asbestos minerals comprise the filirous form of 5 (c.g. calcium, barium) or by passing into an aqueous serpentine, known as chrysolite, and five minerals of solut'o- of low pH c.g. below about 5. the antphibole group, namely: anthophyllite, crocido- M.. > papers of asbestos may be formed simply by' iilc. actinolite, tremolite and amositc, Chrysotilc, one depos.r-.ng a layer of the chemically-opened fibres on a of the most useful and plentiful forms of asbestos, may surface and then removing the water. The polyelectro- be opened into discrete fibrils (a) mechanically by a K* lytcs will act as a binder, becoming insolubilized on combination of crushing and high speed air turbulence healing and producing a tough sheet of material. Other and/or (b) by chemical methods of opening employing uses for these dispersions include the preparation of various known chemical opening agents. rigid, low density panels for sound and heat insulation Chemical opening agents used previously include and battery separators. selected surfactants including fatty acid soaps, acrylic *5 In the attached Figures which illustrate embodiments acid, methacrylic acid or maleic anhydride monomer of and the advantages of a preferred aspect of, the (at acid pH), and saturated amines such as triethanol invention (see Example XIII) amine. Inorganic salts have also been used. In many FIG. I is a photomicrograph at magnification 10450 cases, the degree of opening or the stability of the aque of Chrysotile fibrils opened with polymethacrylic acid ous dispersion is less than desirable, or the residue of 3,1 neutralized with sodium hydroxide and showing glob the agent remaining on the fibrils is deleterious in sub ules of styrene polymerized m situ. sequent use and difficult to remove. The present inven FIG. 2 is a photomicrograph at magnification 10450 tion is believed to have several important advantages of the fibrils opened with a copolymer of styrenc-acry- over former methods. lie acid neutralized with ammonia and showing fine The asbestos employed in the processes and products 2' unifoim-sixed globule*, ol styrene polymerized in situ. of this invention is known as Chrysotilc. Chrysotilc, FIG. 3 is a photomicrograph at magnification 6340 of being a common and plentiful form of asbestos, is the fibrils opened w-iih polyacrylic acid and neutralized widely used as a filler in synthetic organic polymei and copolymeiized with slyiene/dimclhylaminoethyl compositions. However, in order to make best use of its methacrylate (3/11 in situ. reinforcing properties, the mechanically-opened min 3b FIG. 4 is a photomicrograph at magnification 7940 of eral must be separated into its primary fibrils of an the fibrils opened with polyaerylic acid and neutralized average diameter of 250 - 500 A. This mineral should and copnlynicrizcd with methyl mcthacrylate/dime- first be broken up in a preliminary way mechanically as thylaminoelhyl methacrylate (3/1) in situ. in a crusher or chopping mill and then further opened In a preferred aspect of the invention, a basic vinylic c.g. by turbulent, high speed air jets. Mechanical agita 35 monomer is used to neutralize and polymerize onto the tion is not able to separate the individual fibrils from polyelectrolyte, and has basic amino groups or basic each other and form a stable dispersion. The presence heterocyclic nitrogen atoms in the molecule. Suitable of a dispersing agent is therefore necessary to disperse basic monomers include dimethylaminoethyl metha and stabilize the individual fibrils of Chrysotile in wa crylate. t-butylaminoethyl methacrylate and a vinylpyr- ter. 40 idine (as any isomer) or mixtures thereof. If the basic It has been discovered that polyelectrolytes having monomer is used as the sole neutralizing agent it should free carboxylic acid groups and in particular poiy- be present in equivalent amount to neutralize or com acrylic acid, polymethacrylic acid, maleic anhydride bine with the free carboxylic acid groups of the polye- polymers and water-soluble copolymers thereof are Icctrolyte. Mixtures of the various neutralizing agents excellent aqueous dispersing and opening agents for 45 may bc^advantagcous for particular purposes c.g. am Chrysotile. The pH of the solution used for the chemi monia with vinylpyridinc. cal opening should be carefully adjusted to the alkaline Operative inorganic neutralizing agents which may side for best results; preferably a pH of K-10 is main be used in whole or in part include the alkali metal and tained, resulting in dispersions of excellent stability. In ammonium hydroxides. a typical example a 0.5% solution of polyacrvlic acid 5() In some cases, it is advantageous to employ a volatile neutralized to pH 8 with sodium hydroxide is added to base as a neutralizing agent, i.e. ammonia, although any a weighed quantity of mcchanically-opcned Chrysotilc. volatile organic amine may he chosen. The resulting In order to hasten the process of chemical opening the dispersion can be converted to filaments or mats which suspension is subjected to high shear agitation for few after moderate heating to remove the volatile base are minutes, such as in a Waring Blendor. A uniform colloi 55 less sensitive to moisture. In such cases the reactive dal suspension results which shows excellent separation carboxyl groups are believed to form insoluble salts of the individual fibrils when examined under the elec with the magnesium ions present in the asbestos. tron microscope. Lightweight insulating materials have also been pre The amount of dispersing agent may be as little as pared by using tlic above asbestos mats after drying. about 0.1%. based on the weight of dry asbestos or as 60 The polyelectrolyte, after removal of the excess mois great as 1000% for some purposes. The aqueous disper ture serves to chemically bond the submicroscopic sion of asbestos is usually in the range of 1-10% solids fibrils together. Furthermore the polyelectrolyte can be since concentrations above 10% become too viscous to made completely insoluble by post-treatment with al handle. In cases where the polyelectrolyte may act kaline earth tons of calcium or barium. subsequently as a binder, the proportion of polymeric 65 The use of these polyelectrolytes particularly acrylic dispersing agent may be greater than necessary for acid copolymers, methacrylic acid copolymers or ma complete dispersion. Such dispersions are easily spun leic anhydride copolymers offer considerable control into continuous fibres, the resulting fibres showing over the degree of chemical opening, the stability of the -tCa' ; ~i;*- 3,965,284 3 icMilling dispersion, binding efficient:) after drying, and other factors associated with processing and per 4 (made by adding l .0 g. Acrysol A-3 (tradename) to 99 g. distilled water) was adjusted to pH 8 by the addition formance. In addition to the composition of the copoly of ammonia. This solution was added to 5 g. of Chryso mers and choice of neutralizing agent or basic comono tile asbestos shreds (Plastibest No 20) and thoroughly mer. the molecular weight at each stage may be chosen 5 blended in a high-speed mixer of the Waring Blender so as to give optimum processability. type. The resu .ing thick, dough-like mass was placed This invention will be better understood by reference in a beaker and heated to dryness in a radio frequency to the following illustrative examples. (RF) oven. The mass in this case retained its original EXAMPLE 1 shape and occupies a volume equal to that of the origi 10 nal mixture. The density was approximately 8 lb/fl3. Chrysolite asbestos, grade Plastibest No. 20 (trade The tough, rigid mass did not disintegrate even when mark of Canadian Johns-Manville Co., Ltd.) was the boiled for a prolonged period in water, showing that the type of asbestos used. Three grams of coarse mcchani- process is irreversible. Suitable adjustment of the vis cally-shredded fibres were suspended in 297 grams of cosity of the original mixture can be employed to per distilled water containing 1.5 g. of polyacrylic acid 15 mit foaming or expansion to take place during the dry (Acrysol A-3, Rohm and Haas Co.). After three min ing state, thereby resulting in a much lower density. utes agitation at low speed in a Waring Blendor an Such rigid foams are desirable for insulating.purposes equivalent amount of sodium hydroxide solution was where high beat resistance is required. The composi added in order to raise the pH to X. The thick, viscous tion of the polyclectrulytc dispersing agent can be se suspension was further stirred at high speed for 10 20 lected to provide specialized ptopedies for different minutes. Excellent, stable dispersions were formed by applications. this process. No agglomerates or fibre bundles were visible under the microscope. EX AMI'LL VII EXAMPLE II 2.0 g. Chrysotile asbestos shreds (I'lastibest No. 20) 25 were dispersed in 100 g. of a polyatrybc acid solution Chrysotile shreds were treated in exactly the same containing 0.5 g. polyacrylic acid adjusted to pH 8 with manner as in Example 1, but in this case polymcth- ammonia, flic colloidal suspension was spun through a acrylic acid neutralized with ammonia was used as small orifice (a hypodermic syringe) into a coagulating dispersing agent. A 1rk asbestos dispersion in water was bath containing dissolved barium acetate. The precipi prepared, containing 0.25 g. polymethacrylic acid per 30 tated fiber was pulled under slight tension to induce g. of asbestos. Under the electron microscope the com orientation of the asbestos fibrils using a conveyor pletely separated fibrils of average diameter 500 A system in which the speed of drawing could be adjusted were visible. to conform with the speed of extrusion. A slight posi EXAMPLE 111 tive pressure of nitrogen could be employed to control 35 the speed of extrusion through the orifice. A continu 0.75 g. of a styrene/acrylic acid copolymer (carboxyl ous thread was formed with an outer sheath of hard content 0.75 g. cquiv. --COOH per 100 g. of polymer) ened material while the inner core remained fluid until were dissolved in 300 cc of distilled water containing heated to dryness. Reasonably strong, flexihle fibers an equivalent amount of sodium hydroxide to give a pH could be prepared by this technique. If desired, the or about 8. 3 g. of Chrysotile asbestos shreds (Plastibest 40 polyacrylic acid binder could be removed completely No. 20) were added and the suspension was stirred in a by heating the fiber to temperatures above 500C. Waring Blender for 10 minutes. A dispersion of excel These continuous fibers can be used for filament lent stability resulted which showed no agglomerates or winding application or in the manufacture of woven visible particles. materials. EXAMPLE IV 45 EXAMPLE VIII 3 g. of a methyl mcthacrylate/acrylic acid copolymer A Chrysotile asbestos dispersion prepared as in the (carboxyl content 0.54 g. cquiv. --COOH per 100 g. of previous hxample VII was filtered by suction. After the polymer) were dissolved in 300 cc of distilled water filtrate was dried, a very stiff, strong paper-like mat was containing an equivalent amount of sodium hydroxide 50 obtained. A similar product was formed by centrifugal to give a pH of about 8. 300 cc of an I% asbestos dis filtration. The polyacrylic acid provides strong binding persion were then prepared as in Example III with simi forces which increase the toughness and rigidity of the lar results. sheet material. By adjusting the quantity of asbestos, EXAMPLE V . the thickness of the resulting mat can be controlled, 55 thicker sections being suitable for use in building pan 1.2 g. of a slyrene/maleic anhydride copolymer els and lightweight insulating panels for acoustic pur (SMA 1420 A, Sinclair Oil Co.) were dissolved in 300 poses. thermal insulation and fire protection. cc of distilled water containing an equivalent amount of Incorporation of the Chrysotile ultimate fibrils into sodium hydroxide. 300 cc of 0.759f asbestos dispersion the thermoplastic malrics by conventional techniques, were prepared as in Example III and IV (pH about 8). 60 i.e. latex compounding, docs not always ensure uni The resulting suspension was stable and showed excel lent separation of the fibrils. formity of the resulting composition. The present in vention includes a method for coating the individual EXAMPLE VI asbestos fibrils (encapsulation) with a layer of polymer formed by free-radical polymerization in the presence This example illustrates the preparation of a rigid, 65 of the aqueous colloidal Chrysotile dispersions de tough, lightweight expanded structure using the chemi scribed above. This technique is particularly advanta cally-opened coated asbestos fibrils of this invention. geous in the case of asbestos. Encapsulation of opened 100 g. of an aqueous solution of 0.25% polyacrylic acid asbestos fibers with polymer provides several advan- 5 3,965,284 6 tages, namely, ease of molding, lower mixing costs, include styrene, divinylbenzenc. vinyl chloride or fluo formation of translucent composites and several other ride. vinyl acetate, methyl methacrylate, ethyl acrylate, advantages as will be discussed further. acrylonitrile, and nu-thacrylonilrilc. Coaling of some inorganic particles with polymers The concentrations of the individual components for have previously been described in the literature. Parti ' a l' by weight solids asheslos dispersion ensuring cles of macroscopic dimensions are reported to be complete encapsulation should be the following: polye- coated via free-radical or Zic^ler-Natta polymeriza leclrolyte at least about 0.15 g. per g. asbestos, an tion. However, the method used in the present inven equivalent amount of amine monomer, and weight tion is believed to be unique in that an inorganic polyc- ratio of amine to non-basic monomer at least about Icctrolvle-treatcd substrate of colloidal dimensions 0.33. The amount of polymer in the final asbestos com (average diameter 500 A) can be coaled by carrying out the polymerization in aqueous media, eliminating thus the use of expensive and usually nonrecovcrahle organic solvents. The encapsulated fibril products arc also believed to be novel. According to the present invention, a method is also provided which consists of opening and dispersing )S posite may ary from about 2% to 100% by weight of the asbestos. The polymerization may be carried out in sealed containers under nitrogen with appropriate agitation and temperature control for instance at 60C and for time periods varying from about 1 -- 16 hours (until the polymerization is completed as desired). Chrysotile asbestos in water as described above, fol Use of such encapsulated Chrysotile asbestos fibrils is lowed by copolymerization of unsaturated monomers advantageous for several reasons. with a basic amine monomer functioning both as a 2i> a. Greater ease of molding Time periods required for co-monomer and pH controller for the above disper molding are greatly reduced because the resin sur sion. rounds completely, and can wet-out thoroughly the The use of anionic polyelectrolyles (polyacrylic acid, filler. polymethacrylic acid, maleic anhydride polymers and b. Preparation of translucent composites The mate- water-soluble copolymers thereof) as asbestos opening 25 rial can be more easily pigmented and better gloss and and dispersing agents has been described above. The color potential results from the translucent nature of pH of these dispersions is carefully adjusted to about the encapsulated filler. S-IO by using inorganic or organic bases, in order to c. Lower mixing costs and elimination of the use of obtain coated fibril dispersions which are stable. expensive organic solvents. Cheaper grades of asbestos According to this preferred aspect of our invention -,f< can be employed in many cases. the organic bases used to neutralize the polyelectroh tc ri. Reduced die and tool wear during injection mold may jnclude cationic organic compounds having poly ing ot extrusion due to inherent lubrication. merizable sites such as dimeihylaminoeihyl methacry c. High heat distortion temperatures due to the large lates, t-bulylaminoethyl methacrylate or vinylpyridinc. surface area of the opened asbestos fibrils. Organic or inorganic bases which may be present also, 33 f. Greater ease of handling, iess dusting and conse include ammonia, amines, sodium hydroxide, potas quently less danger of cancer and lung disorders (*`as- sium hydroxide or lithium hydroxide as described bestosis"). above. Vinylic non-basic comonomers, are preferably Another application is the manufacture of asbestos present along with the basic comonomer. foams. The polymerization-encapsulation may be car In a typical example, a 0.5 % solution of polyacrylic ried out in the presence of an oil-soluble blowing agent acid neutralized with dimethylaminoethyl methacrylate which decomposes during molding, forming a light was added to a weighed quantity of asbestos shreds and weight encapsulated asbestos foam. Examples of suit the mixture agitated in a high-speed Waring Blender able blowing agents are azobisformamide, azobisisobu- for 10 minutes. To the resulting stable opened disper sion was added a ncn-basic monomer such as styrene which contained an oil-soluble initiator such as azobis- isobutyronitrile (AIBN). The weight ratio of basic amine comonomer to non-basic monomer (styrene) should be at least about one-third for complete encap 4S tyronitrile, N.N'-dinitrosopentamethylene tetramine, and toluene-4-sulfonyl hydrazide. This further aspect of the invention will be better understood by reference to the following representa tive examples; sulation. After the polymerization, completely-coated 50 EXAMPLE IX individual Chrysotile fibers were precipitated out and easily recovered. This material after filtering and dry 3 g. Chrysotile asbestos, grade Plastibest No. 20 were ing can be easily molded to give translucent specimens of excellent properties. added to 300 cc of a 0.3 % aqueous polyacrylic acid solution (Acrysol A-3, tradename of Rohm and Haas Encapsulation with other polymers is feasible by this 55 Company) and the mixture was agitated for three min method and is independent of the aqueous solubility of utes at low speed in a Waring Blendor. 1.96 g. dimeth- the added non-basic monomers, provided that the ylaminoethyl methacrylate were then added dropwise weight ratio of amine to non-basic monomer is not less to pH 8 and stirring was continued at high speed for a than one-third. Use of oil-soluble initiators such as total period of 10 minutes. A stable dispersion of colloi- benzoyl peroxide, lauryl peroxide, methylethylketone 60 dat Chrysotile (average diameter 500 A) was pro peroxide, diisoproplyperoxydicarbonate, and AIBN is preferable in order to minimize the formation of exces duced. 5.88 g. styrene containing 0.5% azobisisobutyronitrile (AIHN) were then added. After 16 hours at sive free polymer, i.e. polymer not attached to the completely coated asbestos fibers precipitated. surface of the fibrils. The material was then filtered, dried and molded to The non-basic vinylic comonomer incorporated to 65 give excellent translucent specimens. The asbestos polymerize with the basic monomer (and thus onto the content of the encapsulated material, determined by polyelectrolyte), may be any other vinyl monomer ashing, was found to be 27.8% by weight, in good polymerizable in aqueous systems. Such monomers agreement with the feed composition. 78 to resist-acids or bases, or other corrosive environments EXAMPLE X which would normally destroy the asbestos. Solvent- The same procedure was repeated as in Example IX. resistant sheaths may be provided using acrylonitrile but in this case the amount of po'yacrylic acid w as 0.15 copolymers as the encapsulating material. It is apparent g. per g. of asbestos. Equivalent amounts of dimethyl- 5 that only a continuous coating would provide a coher aminoethyl methacrylate and ainine/slyiene weight ent network, and that encapsulation must be essentially -alio 1/3 were used. The final encapsulated material complete. The individual coated fibrils may be fused or containing 46.6% asbestos was easily molded to give a joined together at their crossover points by the mild uniform, translucent specimen. application of heal and pressure. EXAMPLE XI 10 We claim: 1. A method of chemically opening chrysotile asbes The same procedure was repealed as in Example IX tos into individual fibrils and at least partially encapsu and X."but in this case methyl methacrylate was used lating with polymer comprising: instead of styione. A very desirable product was ob a. physically breaking up the asbestos and shredding tained. IS the fibres to a preliminary stage. EXAMPLE XII b. dispersing the resulting asbestos shreds in an aque ous alkaline medium of alkaline pH up to about 10 1 g. Chrysolite asbestos was dispersed in 100 cc water containing a soluble vinylic polymer polyelectro with 0.15 g. polyacrylic acid and 0.3 g. dimethylamino- lyte having free carboxylic acid groups, with agita cthyl methacrylate. 0.9 g. ethyl acrylate containing 20 tion to chemically open and coat the individual C.S'rf A1BN were then added and polymerization pro asbestos fibrils, and ceeded at 60CC for 16 hours. After the completion of c. insolubili/.ing the polyelectrolyte on the fibrils, and the reaction, 2 g. styrene containing additional catalyst separating coated fibrils from the aqueous medium. were added and the polymerization continued at the 2. The method of claim 1 wherein the polyelectrolyte same temperature for 1 2 hours. Coated Chrysotile with 25 is selected from the group consisting of polymers of two successive layers of polymer were precipitated in acrylic acid, polymers of melhacrylie acid, and copoly the form of easily filtered spheres. Specimens prepared mers of maleic anhydride from this material showed improved Izod impact 3. The method of claim 1 wherein the pH of the strengths, due to the prcssence of the energy-absorbing aqueous medium is adjusted to about 8-10. polymeric layer on the surface of the fibrils. 30 4. The method of claim 1 v. herein the polyelectrolyte EXAMPLE XIII is insohtbilized in (c) with an inorganic or volatile or ganic base. Typical polymer-fibril products were examined 5. The method of claim 1 wherein the polyelectrolyte under the electron microscope. In each case the asbes on the fibrils is reacted and polymerized with a basic tos fibrils were chemically opened with the vinyl poly 35 vinylic monomer. mer polyelectrolyte having carboxylic acid groups, 6. The method of claim 1 wherein the polyelectrolyte giving very good opening and dispersion of the individ is insolubilized and reacted and polymerized with both ual fibrils. In FIGS. I and 2, the fine individual fibrils a basic vinylic comonomer and non-basic vinylic como are clearly shown. nomer to encapsulate the individual fibrils with poly FIG. 1 shows the polymerization behaviour of styrene 40 mer, the weight ratio of basic to non-basic comonomer when sodium hydroxide was used to neutralize poly- being at least about 0.33 methacrylic acid the latter acting as the asbestos open 7. A method of chemically opening chrysotile asbes ing and dispersing agent. There was hardly any polymer tos into individual fibrils and encapsulating the fibrils attached onto the fibrils in this case, and the major part with polymer as in claim 1 comprising: of the polymer precipitated during polymerization. In 45 a. physically breaking up the asbestos and shredding FIG. 2, the effect of a more efficient dispersing agent (a the fibres to a preliminary stage, copolymer of styrene-acrylic acid neutralized with am b. dispersing the resulting asbestos shreds in an aque monia) is shown. Many small polystyrene particles ous medium of pH about 8-10 containing both . partly attached to some of the fibrils are formed when styrene is polymerized in situ. (A1BN initiator was used 50 soluble vinylic polymer polyelectrolyte selected from the group consisting of polymers of acrylic for the styrene polymerization in both these cases). acid, polymers of methacrylic acid, and copoly Upon filtration of this suspension the bulk of the poly mers of maleic anhydride and a basic vinylic mono mer is recovered in the filtrate. mer selected from the group consisting of dimeth- FIG. 3 shows individual fibrils opened and dispersed with polyacrylic acid and completely coated with co 55 ylaminocthyl methacrylate, t-butyluminoethyl methacrylate and a vinylpyridine, with agitation to polymer formed in situ from styrene/dimethylamino- chemically open and coat the individual asbestos cthyl methacrylate (3/1) using AIBN initiator. In FIG. fibrils, and 4 the fibrils were opened and dispersed with polyacrylic c. insolubilizing the polyelectrolyte, polymerizing the acid, and coated with copolymer formed from methyl mcthacrylate/dimcthylaminoethyl methacrylate (3/1) 60 monomer and separating the encapsulated fibrils from aqueous niedia. and AIBN initiator. In both these Figures, the polymer is seen to completely encapsulate and adhere to the 8. A method of chemically-opening chrysotile asbes tos into individual fibrils and encapsulating the fibrils individual fibrils. with polymer comprising: Encapsulated asbestos fibrils may be partially fused a physically breaking up the asbestos and shredding into sheets, tubes, or other shapes to be used as porous 65 the fibres to a preliminary stage, filter webs of extreme fineness such that only the finest b. dispersing the resulting asbestos shreds in an aque particles may pass through the reticulated structure ous medium of alkaline pH up to about 10 contain The type of polymeric encapsulation may be selected ing 3,965,284 9 10 i. a soluble vinylic polymer polyelcctrolyte selected from the group consisting of polymers of acrylic acid, polymers of mcthaciylic acid, and copoly 9. The method of claim 8 wherein the non-basic monomer is a styrene and an oil-soluble initiator is used. 10. Chemically-opened, chrysotile asbestos fibrils mers of maleic anhydride; 5 encapsulated with polymer comprising a vinylic poly ii. basic vinylic monomer selected from the group mer polyelcctrolyte and po'ymerized basic vinylic consisting of dimethylaminoethyl methacrylate, t-buiylaminoethyl methacrylate and a vinylpyri- monomer, the polyelcctrolyte having carboxylic acid groups neutralized by the basic groups of said mono mer, the amount of polymer being from about 2 to dine; and |0 100% by weight of the asbestos. iii. non-basic vinylic comonomer and a polymeriza 11. The encapsulated fibrils of claim 10 wherein the tion initiator therefor; to chemically open and basic vinylic monomer is selected from the group con coat the individual asbestos fibrils, the weight ratio of basic monomer to non-basic comonomer sisting of dimethylaminoethyl methacrylate, tbutylaminoethyl methacrylate and a vinylpyridine. 12. The encapsulated fibrils of claim 10 wherein the being at least about 0.33, and 15 polymer comprises non-basic vinylic monomer copoly- c. insolubilizing the polyelcctrolyte, copolymerizing merized with said basic monomer. the basic and non-basic monomers to encapsulate 13. The encapsulated fibrils of claim 10 wherein the the fibrils with polyelcctrolyte and copolymer, and polyelcctrolyte is selected from the group consisting of polymers of acrylic acid, polymers of methacrylic acid. separating the encapsulated fibrils from aqueous 2o and copolymers of maleic anhydride., media. ** 25 30 35 40 45 50 \ 55 60 65 CUO * UJVlK Uuj. ntrun 1 *v CUSTOMER & nr.tnnK' Montello - Tulsa, Oklahoma. 'INDUSTRY ^ .. ^ . CLASSIFICATION _WStrtbutor------ "SALESMAN. J.E. Velsh RFr.nrj Southern _PATE OF CALL___LL21. ASBESTOS WEALTH REGULATORY DOCUMENTS PROVIDED: D USDS o Health l OSHA Information Blue Book n Dust Count Report O Other, specify below PERSONS INTERVIEWED: Km Campbell - President Chuck Petri - Ofifilce Marager CALL OBJECTIVE: Call made cut the home ofifilce ofi oua distributor to the oil well Industry. RESULTS OF CALL: This was the filrst visit to Hontello's new 6howpZa.ce ofifilce location since they moved out ofi their combZnatZon ofifilce-warehouse Zn Sand Springs. MonteZlo own6 thZ6 one story 11M 6q. fit. buZZdZng and. occupies about 4M 6q. fit. with luxury decor. This has been another, good bu&Zne66 yean fior Montello Km 6aZd and they expect to cZo6e their filscal yean, on June 30 wZth about $5MM 6aZe6 i/a $3.5MM Za6t yean.. The oZZ wetted peZZet project has bem goZng along 6moothZy with Chemical Sealing Zn Kansas City, but they have expenlmced a 6lZght delay Zn getting bag6. They need polypropylme lined krafit bag6 a6 the oil used 6eep6 tknough polyethylme and they will be u&Zng an International Paper bag currently being manufiactured to package explosives and ammunition type product6. The oil wetted product will be known simply as "Unlvls" and Km expects a complete 6hlfit firom Supervl6 and Shurellfit sales to the oil wetted material. The UnZvls bags will have the asbestos warning and Km expects that sales should grow back up to around 5,000 tons a year again. Afiter a success fiul trial It Zooks like fiuZl scale production wilt occur at Chemical Sealing's West Coast plant In Union City, Callfiornla to help reduce the transportation costs. FOLLOW-UP ACTION REQUIRED: -COPIES TO- JRk*TPN: JLM! :KC~F1LE?NF--FILE MF PERHANEKT FILE F~)