US2537111A

US2537111A - Tracing cloth and the like and method of preparing same

Info

Publication number: US2537111A
Application number: US36443A
Authority: US
Inventors: Jr Horace Wood
Original assignee: Monsanto Chemicals Ltd
Current assignee: Monsanto Chemicals Ltd; Monsanto Chemical Co
Priority date: 1948-07-01
Filing date: 1948-07-01
Publication date: 1951-01-09
Anticipated expiration: 1968-01-09
Also published as: GB689381A

Description

Patented Jan. 9, 1951 2,55'Lili TBACING CLOTH AND THE LIKE AN!) METHOD- OF PREPARING SAME Horace Wood, Jan, Wal efield-, Mass., assignor to Monsanto. ilhemi'cal' Company, St. Louis, Mo., a

corporation of Delaware No Drawing. Application July, 1, 1948, Serial No. 36,443.

14; Claims. 1

The present invention relates to a method of preparing improved tracing cloth, hol'land cloth and thelike and to the-coated articles-per se. It more particularly relates to a method of preparing; improved tracing cloth and the likewhich is especially adapted to besensitized with a photographic emulsion coating.

Tracing cloth has, in general, been manufacured heretofore by; first impregnating a woven cotton fabric, fabricated; from. fine lon staple o on y ms; with starcnewatermixture, after which, the, f abric; is; dried; and-guper-calendered or friction-calendered ata; high temperature as, for example, about no? F It is. not: possible todirectly; coat, the: starch impregnated fabric; with a photographic gelatin emulsion; since thestarch is Water sensitive and, isremoved from; the: fabric to a, considerable extent onimmersion in water and, therefore, could: not, suitablywithstand the d v lop ng, and Washing. p ess s: normally employed in photographic, reproduction work. Therefore. order to, employ, starch impreghated. abrics or is useithas be n e ss y to coatsuch fabricswith a clear water-resistant film, r ating. fni rncellulosa ethylicellulose or he ik antecedent o the application there f a phot r phi u si nc atina.

The; foregoing method leaves much to be, desired. For examplait is diilicult to amalyw a completely'protective nitrocellulose or other. water resistant coating over the starch impregnant. Such-acoating is necessary, however, in. order to prevent water from swelling the starch and;c au sin image distortion and/or peeling of the protective coatin and the like. In practice com plete protection of the starch from the water used in the photographic reproduction processes is not always achieved with; the result that the photographic reproduction must at times be rejected as not being suitable for its intendeduse whether it be. used as a master print or" a copy. 'Ifheabove described method is also relatively in,- efii'oient invthatyextraisteps are employedin manufacturing the lacquered. tracing cloth, and, therefore. requires :1 the use of I considerable extra cqu nmen randclabor.

Ifhe same difiicultiesexist; in varying degrees the; manufacture, of; holland: cloth, surveying es; meas r nge-tapesand: the like.

The present; invention; provides: a. process. for m nu a urin tra ing clothL holland cloth. and the like, which is; not; only: efficiently. and; economically carried out, but: which-also eliminates many. of theforflgilihfl; ind'bther difficulties and Qi e ra e s he!pr nrartzprocessesiandrtne rretluc ssmt pa ed bnsuch processes/e.

It is one object of the present invention to manufacture a tracing cloth, holland cloth and the like for photographic and non-photographic uses by employin a coating impregnant which is notonly water-resistant and flexible, but which is also capable of being suitably super-calendered and glazed.

A further object of the invention is to provide a simple and efiicient process for manufacturing tracing'cloth especially suitable for photographic reproduction uses.

A further object of the invention is to produce by the use of a single impregnant a tracing cloth which is especially adapted to be sensitized with photographic emulsion coatings and which can be rocessed in Water solutions Without the use of an additional water-resistant coating.

Still further objects and advantages of the present invention will appear from the following description and the appended claims.

The invention is practiced, in general, by first impregnating a fabric, which is suitable as a base for tracing cloth, holland cloth, measuring tape or the like, with an organic solvent solution com-- prising as an essential film-forming material a copolymer of a polymerizable vinyl compound havin the structural formula RCH=CH2, where R is a phenyl or substituted pheny-l radical, with a secondary alkyl half ester of an ethylene -a,e-dicarboxylic acid, in which the alkyl group contains from: 4 to 12' carbon atoms. The impregnating solution preferably also contains a minor proportion, based on said copolymer, of polyviny1 butyral. After the fabric is impregnated in the manner indicated, it is heated to evaporate the organic solvent or dried in suitable manner. and is then frictionecalendered or supercalendered using heat and pressure to glaze the film-forming materialor materials.

A clear coating is formed by. the above procedure, but such coating may be opacified, if desred, by incorporating a small amount of pigment, flatting agent and the like in the impregnation solution. The super-calendered fabric possesses, sufficient water-resistance to be employed as a non-sensitized tracing, cloth, as holland cloth and the like. When the superecal- .endereo. fabric is to be employed in the manu- Ifacture of lightsensit've tracing cloth and the like, the resistance of the coating thereon to water and organic solvents is preferably improved, however, by incorporating in the impregnatingsolution a relatively small proportion, say

about 0.5 to 5% by weight, of a compound'which is capable of cross-linking the carboxyl' groups in the copolymer. As 'examples of such crosslinking compounds may be mentioned formaldehyde; amino-aldehyde monomeric or low polymeric resins; phenol-formaldehyde monomeric or low polymeric resins; alkylene polyamines such as ethylene diamine, propylene diamine, butylene diamine and the Ike; and polyglycols such as triethylene glycol, tetraethylene glycol and the like. When the impregnating solution contains such compounds, the film-forming materials described above are at least partially crosslinked or otherwise inter-reacted to produce a film or coating which is substantially resistant to the organic solvents in which they are originally soluble. The cross-linking or mutual reaction of at least a portion of the film-forming materials in the presence of such a cross-linking compound is accelerated by heat and/or an acid type catalyst. It is preferable when the above compounds are employed to heat the supercalendered fabrics at temperatures between about 225 F. to 330 F. in the presence of an acid catalyst such as tartaric acid, ethyl phosphoric acid, oxalic acid, citric acid or the like as, for example, for a period of from 1 to minutes, depending upon the temperature used, to accelerate the cross-linking or curing of the film-forming materials. Normally, the above copolymers and the polyvinyl butyral resin mutually react or cross-link at least partially merely on aging without the use of such cross-linking compounds, but the cross-linking generally proceeds at a relatively slow rate under such conditions.

Of the above described cross-linking compounds or agents, the amino-aldehyde resins are preferably employed. As examples of such resins may be mentioned urea-formaldehyde resins such as methylol urea and di-methylol urea; alkylated urea-formaldehyde resins or alkoxy alkyl urea resins such as methoxy methy1 urea, di- (methoxy methyl) urea, (methoxy methyl) methylol urea and the like; melamine-aldehyde resins such as the methylol melamines and particularly those having from 1 to 4 methylol groups per mol of melamine and the like; and alkylated melamine-aldehyde resins or alkoxy alkyl melamine resins such as (methoxy methyl) monomethylol melamine, di-(methoxy methyl) monomethylol melamine, di-(methoxy methyl) dimethylol melamine and the like or mixtures thereof. Of these the methyl ethers of methylol melamines or methylated melamine-formaldehyde resins of the type last described are preferred.

The copolymers employed herein as essential film-forming materials may be prepared in a variety of ways, but are generally prepared by copolymerizing by various Well-known methods a polymerizable vinyl compound, having the structural formula R,CH=CH2, Where R is a phenyl radical, a halogen substituted phenyl radical such as chloro phenyl, dichlor phenyl and the like, or a methyl substituted phenyl radical such as methyl phenyl, dimethyl phenyl and the like with a secondary half ester of an ethylene afi-dlcarboxylic acid in which the alkyl group contains from 4 to 12 carbon atoms and preferably 6 to 10 carbon atoms. The vinyl compound and half ester are generally copolymerized in a molal ratio Varying between about 2:1 to 1:1 and preferably in a molal ratio of 1.5:1 to 1.121. The secondary alkyl ester of an ethylene afi-dicarboxylic acid may also comprise a small proportion of an ethylene a,/3-dicarboxylic acid or anhydride.

As examples of such secondary half esters may Cir bemention-ed sec.-butylacid maleate,butylmethyl carbinyl acid maleate, methyl amyl carbinyl acid maleate, methyl hexyl carbinyl acid maleate, methyl heptyl carb'nyl acid maleate, methyl decyl carbinyl acid maleate and the like, the corresponding acid fumarates and the like.

The secondary alkyl half esters are prepared, in general, by reacting a secondary alcohol as, for example, secondary butyl alcohol, methyl isobutyl carbinol and the like with an ethylene a,/i-dicarboxylic acid or anhydride such as maleic acid, fumaric acid, maleic anhydride and the like. The alcohol and acid or anhydride are preferably reacted in a molal ratio varying between about lzl to 1:1.6. The unreacted alcohol, acid or anhydride can be removed or separated from the secondary alkyl ester so formed, if desired, or the entire mass can be employed in the subsequent polymerization with the above described vinyl compounds.

The above described copolymers may be prepared, if the secondary alkyl half ester and vinyl compound are mutually soluble, by mass polymerization which involves heating the reactants or monomers at temperatures varying between about to 300 0., usually, in the presence of a catalyst as, for example, a peroxide catalyst such as benzoyl peroxide. If the half-ester and vinyl compound are not mutually soluble, the copolymer may be prepared, for example, by emulsion polymerizing the monomers or by copolymerizing the monomers in a solvent for the monomers and copolymer. In the latter case the copolymer may be precipitated after it is formed, for example, by adding an inert diluent to the reaction mixture. The precipitated copolymer can then be separated from the mixture by filtration, centrifuging and the like.

The copolymers employed in the present invention are, in general, soluble in a wide variety of organic solvents and solvent mixtures. As examples of these may be mentioned: alcohols such as methanol, ethanol, isopropanol, n-propanol, butanol and the like; esters of acetic acid such as ethyl acetate, propyl acetate, butyl acetate and. the like; ketones such as acetone, diethyl ketone, methyl ethyl ketone, methyl isobutyl ketone and the like; mixtures of alcohols or acetates with aromatic or aliphatic hydrocarbons as, for example, such mixtures as ethanol-toluol, propanol-toluol, ethyl acetate-toluol, ethanolpetroleum naphtha fractions; propanol-petroleum naphtha fractions, ethyl acetate-petroleum naphtha fractions and the like. The foregoing solvents, generally Speaking, are also solvents for a mixture of the above copolymers, polyvinyl butyral and the above described cross-linking compounds.

Solutions of the above copolymers in the foregoing solvents or solvent mixtures can be applied to a fabric suitable for tracing cloth, holland cloth and the like in various ways as, for example, by knife coating, roll coating, and the like or by immersing the fabric in the solution and then removing the excess solution. Other methods of application may also be employed. The quantity of polymer present in such solution may be varied considerably depending upon the means used to apply the solution to the fabric, the particular end use of the fabric, the viscosity of the copolymer in the solution, the quantity of other film-forming material or compounds of the type hereinbefore described present in the solution etc. In general, from about 5 to 30% by weight .bf' the" copolyme'r is '-used in the impregnating s'oluti'on when su'ch copolymer is present as the sole film forming material. 'When, in-addition, polyvinyl butyraland/or the 'above' described cross-linking -compounds' are also employed in In a preferred embodiment "of the invention polyvinyl butyral and a cross-linking compound or agent of the type hereinbefore described are employed along with theabove described copolymers to give improved flexibility and-solvent resistance to' the tracing cloth. The quantity of polyvinyl butyral present in the impregnating "solution'depends to'a' considerable extent on the "degree of flexibility desired in the finished cloth or fabric. weight of polyvinyl "butyral, based on the 'copoly- 'mer', is imployed in theimpregnating solution,

In general, from about 1 to 35% by while from about to by weight of polyvinyl buty'ral; based on the copolymer, is preferably employed.

Afurther understanding of the present in- 'vention will be obtained from the following examples which are intended to be illustrative of the invention, but not limitative "of the scope ."thereof, parts and percentages being by weight.

thus prepared was copolymerized with about 115 molecular proportions'of styrene in the presence 1 *of about 0.003 molecular proportion of benzoyl I peroxide.

The reaction'was initiated at about C.and this temperature was maintainedduring the periodof rapid heat evolution. The temperature of the mass was then raised to 120 C. fora period of 1 /2 hours to complete the reaction. On cooling, ahard, "glassy resin was obtained which was com'minuted to "make it more readily soluble.

An impregnating solution was made up conta ning 20 parts of copolymer A (as prepared above) and parts of specialdenatured alcohol No. l and this solution wasknife coated onto a bleached cotton woven fabric weighing 1.9 oz.

per square yard and having about warp ends.- and '87 filling yarns per-inch. The impregnated fabric was 'driedat about for approximately 5 minutes "in a tunnel drier. The other surface of the fabric was then impregnated and dried in a similar manner and the fabric was then friction-calenderedusing a three roll friction-calender. The friction roll of the calender was rotated at a peripheral velocity 2 times greater than the peripheral velocity of the fabric rolls. During the friction-calcnderingoperation,

Example II SOIfitiehwas-prepared "Whi h "cont med 14 p rtsb 'c e'p olymr-A (prepareaas dsb bed ih jE-kahlble -I), --6'- par tS (if-polyvinyl "sa ty anc ents of'speci'al denatured alcohol ti'on wasron ocated onto a ti; n-ratrrc weighing--r.c; ez;-persquare nd ha'ving 85 war ends "ahd B'T filling yarns inch. The inipregnated abscess driedat ates l-00" F.- o'r (l fniiiutes. The-othersurface 'of the at was m pre'g'nated -and dried by a i131 pi-oced iire and the fabric was then given passes thfo'li gha three IG'I-I fl'lCti-OI'IECaIB'Iider.

The friction roll of the calender 'was driven" at "tihresthe: "peripheral velocity of the feed rolls. ehiper'atlire of"th'e -rolls'was aboi1t*320 F. *and the preset-teen "the fabric was about 15 tons *pe liiiear Thesurfac'ebf the fabric which een' exposed to the friction roll was smooth my grazed. 1 116;tracing cloth eo pioduce'd "I y water resrstant and possessed good flexibility.

-A-n impregnating solution was prepared which contained l7.5 .parts of copolymer A (prepared as described in Example I), 7.5 parts of polyvinyl 'butyral; 2.1- parts of anaqueous solution consisting-of-60% 'byweightofdi-(methoXymethyl) dirnethylol melamine and 72.9 parts of a solvent mixture consisting of"40 special denatured alcohol No.-l and 66% toluol. This solution was 'kn'ife coatedonto a. woven bleached cotton fabric having substantially the same weighta-nd construction as that described in Example- I. The fabric was dried at about-15F. for Erminutes and the other surface was then impregnated with the solution and dried using the same procedure.

Thedry impregnated fabric was given three passes through a three roll friction-calender wherein the friction roll "was driven at 3 times theperipher-al velocity of the feeding rolls. .The

temperature of the rolls was maintained at about 315 F. and the pressure on the fabric was approximately 13.5 tons per linear inch. The tracing cloth was then heated to a temperature of 250 to 260? F. for a period of 5 minutes to cure or cross-link the film-forming materials.

The cured tracing cloth ishighly flexible and co resistant to water, alcohol, and alcohol-hydrocarbon mixtures. 'It is also resistant to other :erganic liquids which are normally solvents for the copolymer andpolyvinyl butyral.

Thepolyvinyl butyral employed in the foregoing examples was prepared by condensing 'buty-raldehyde with a'partially hydrolyzed polyvinyl acetate and contained on aweight basis 1'7 to20'% hydroxygroups calculated as'polyvinyl alcohol; less than 3 acetate groups calculated as 7 0 polyvinyl acetate and the remainder substantially butyraldehyde acetal. Instead of this specific polyvinyl butyral other polyvinylbutyrals having lower hydroxy contents, higher acetate contents and/or lower viscosity may be employed. In fl l-r he,l perties of the film formed rrcm the foregoing copolymers together with polyvinyl -butyra1 as, for example, extensibility, flexibility and hardness will depend to a certain extent on the particular composition of the polyvinyl butyral and the method employed in preparing it. For these reasons, it will be apparent that the im- -.pregnating solutions described herein may be modified to a certain extent depending upon the characteristics of the polyvinyl butyral that is.

employed.

In the foregoing description and examples other conditions of drying and super-calendering the impregnated fabric may be used. For example, the impregnated cloth may be dried at any temperature which drives off the solvent contained in the impregnating solution, but is preferably dried at temperatures which allow the solvent to be released at such a rate whereby formation of blisters or bubbles on the fabric surface is avoided. If speed of drying is unimportant the impregnated fabric can be dried at normal room temperatures. The fabric can be dried satisfactorily, for example, at temperatures varying between about 90 to 120 F.

Calendering may be carried out by using other means and conditions than those described above. For example, the dried impregnated fabric may be super-calendered by hand ironing using a hot iron to cause thermoplastic flow of the coplymer and polyvinyl butyral, if the latter is also employed. When super-calendering is effected by friction-calendering the various conditions of operating the friction calender may be varied depending upon the type of apparatus employed and the end use of the impregnated and calendered fabric. In general, the impregnated fabric is super-calendered at temperatures and pressures which will cause the copolymer to soften or flow into a substantially continuous film or surface. Suitable temperatures for super-calendering vary between about 275 to 330 F., while temperatures of about 310 to 325 F. are preferably employed. However, other temperatures may be used depending upon the particular copolymer used and the ratio of copolymer to polyvinyl butyral employed in the impregnating solution.

What is claimed is:

'1. A method of producing tracing cloth which comprises impregnating a Woven cotton fabric which is suitable as a base for tracing cloth with anorganic solvent solution comprising 1) from to 30% by weight of a copolymer consisting of a secondary alkyl half ester of an ethylene 1,5 dicarboxylic acid selected from the group consisting of maleic and fumaric acids, and a polymerizable vinyl compound having the structural formula: RCH=CH2, where R is selected from the group consisting of a phenyl, halogen substituted phenyl and methyl substituted phenyl radical, said half ester and said vinyl compound being copolymerized in a molal ratio between 1:1 and 1:2, (2) a minor proportion, based on said copolymer, of polyvinyl butyral, (3) from 0.5 to 5% by weight of a compound selected from the group consisting of formaldehyde, phenol-formaldehyde rcsins,urea-aldehyde resins, alkoxy alkyl urea resins, melamine-aldehyde resins, alkoxy alkyl melamine resins, alkylene polyamines and polyglyco-ls and (4) an organic solvent for the foregoing ingredients, said solution comprising from 6 to 32% by weight of solids; drying said fabric and then friction-calendering said fabric. 2. A method of producing tracing cloth which comprises impregnating a woven cotton fabric which is suitable as a base for tracing cloth with an organic solvent solution comprising (1) from 5 to 30% by weight of a copolymer consisting of a secondary alkyl-half ester of an ethylene (1,3 dicarboxylic acid selected from the group consisting of maleic and fumaric acids, in which the alkyl group contains from 4 to 12 carbon atoms, and styrene, said half ester and styrene being copolymerized in a molal ratio between 1:1 and 1:2, (2) a minor proportion, based on said copolymer, of polyvinyl butyral, (3) from 0.5 to 5% by weight of a compound selected from the group consisting of formaldehyde, phenol-formaldehyde resins,,urea-aldehyde resins, alkoxy alkyl urea resins, melamine-aldehyde resins, alkoxy alkyl melamine resins, alkylene polyamines and polyglycols and (4) an organic solvent for the foregoing ingredients, said solution comprising from 6 to 32% by weight of solids; drying said fabric and then friction-calenderin-g said fabric. 3. A method of producing tracing cloth which comprises impregnating a woven cotton fabric which is suitable as a base for tracing cloth with an organic solvent solution comprising (1) from 5 to 30% by weight of a copolymer consisting of a secondary alkyl half ester of an ethylene ,3 dicarboxylic acid selected from the group consisting of maleic and fumaric acids, in which the alkyl group contains from 6 to 10 carbon atoms, and styrene, said half ester and styrene being copolymerized in a molal ratio between 1:1 and 1:2, (2) a minor proportion, based on said copolymer, of polyvinyl butyral, (3) from 0.5 to 5% by weight of a methyl ether of methylol melamine and (4) an organic solvent for the foregoin ingredients, said solution comprising from 6 to 32% by weight of solids; drying said fabric and then friction-calendering said fabric. 4. A method according to claim 3, but further characterized in that the secondary alkyl half ester is methyl isobutyl carbinyl acid maleate.

5. A method according to claim 3, but further characterized in that the secondary alkyl half ester is methyl amyl carbinyl acid maleate.

6. A method according to claim 3, but further characterized in that the secondary alkyl half ester is methyl hexyl carbinyl acid maleate.

7. A friction-calendered tracing cloth which consists essentially of a woven cotton fabric suitable as a base for tracing cloth impregnated with a copolymer consisting of a secondary alkyl half ester of an ethylene (1, 8 dicarboxylic acid selected from the group consisting of maleic and fumaric acids, and a polymerizable vinyl compound having the structural formula: RCH=CH2, where R is a member of the class consisting of a phenyl, halogen substituted phenyl and methyl substituted phenyl radical, said half ester and said vinyl compound being cogolymerized in a molal ratio between 1:1 and l:

8. A friction-calendered tracing cloth which consists essentially of a woven cotton fabric suitable as a base for tracing cloth impregnated with 1) a copolymer consisting of a secondary alkyl half ester of an ethylene afi dicarboxylic acid selected from the group consisting of maleic and fumaric acids, and a polymerizable vinyl compound having the structural formula: R-CH=CH2, where R is selected from the group consisting of a phenyl, halogen substituted phenyl and methyl substituted phenyl radical, said half ester and said vinyl compound being copolymerized in a molal ratio between 1:1 and 1:2, and (2) a minor proportion, based on said copolymer, of polyvinyl butyral.

9. A friction-calendered tracing cloth which consists essentially of a woven cotton fabric suitable as a base for tracing cloth impregnated with (l) a copolymer consisting of a secondary alkyl half ester of an ethylene afi dicarboxylic acid selected from the group consisting of maleic and fumaric acids, and a polymerizable vinyl compound having the structural formula:

Where R is selected from the group consisting of a phenyl, halogen substituted phenyl and methyl substituted phenyl radical, said half ester and said vinyl compound being copolymerized in a molal ratio between 1:1 and 1:2, (2) a minor proportion, based on said copolymer, of polyvinyl butyral and (3) a small proportion of a compound selected from the groupconsisting of formaldehyde, phenol formaldehyde resins, urea-aldehyde resins, alkoxy alkyl urea resins, melamine-aldehyde resins, alkoxy alkyl melamine resins, alkylene polyamines and polyglycols, said copolymer, butyral and last named compound being at least partly inter-reacted.

10. A friction-calendered tracing cloth which consists essentially of a woven cotton fabric suitable as a base for tracing cloth impregnated with (l) a copolymer consisting of a secondary alkyl half ester of an ethylene ,5 dicarboxylic acid selected from the group consisting of maleic and fumaric acids, in which the alkyl group contains from 4 to 12 carbon atoms, and styrene, said half ester and styrene being copolymerized in a molal ratio between 1:1 and 1:2, (2) a minor proportion, based on said copolymer, of polyvinyl butyral and (3) a small proportion of a compound selected from the group consisting of formaldehyde, phenol-formaldehyde resins, ureaaldehyde resins, alkoxy alkyl urea resins, melamine-aldehyde resins, alkoxy alkyl melamine resins, alkylene polyamines and polyglycols, said copolymer, butyral and last named compound being at least partly inter-reacted.

11. A friction-calendered tracing cloth which consists essentially of a woven cotton fabric suitable as a base for tracing cloth impregnated with (1) a copolymer consisting of a secondary alkyl half ester f an ethylene 11,5 dicarboxylic acid selected from the group consisting of maleic and fumaric acids, in which the alkyl group contains from 6 to 10 carbon atoms, and styrene, said half ester and styrene being copolymerized in a molal ratio between 1:1 and 1:2, (2) a minor proportion, based on said copolymer, of polyvinyl butyral and (3) a small proportion of a methyl ether of methylol melamine, said copolymer,

10 butyral and methyl ether being at least partly inter-reacted.

12. A friction-calendered tracing cloth which consists essentially of a woven cotton fabric suitable as a base for tracing cloth impregnated with (1) a copolymer consisting of methyl isobutyl carbinyl acid maleate and styrene, said maleate and styrene being copolymerized in a binyl acid maleate and styrene, said maleate and styrene being copolymerized in a molal ratio between 1:1 and 1:2, (2) a minor proportion, based on said copolymer, of polyvinyl butyral and (3) a small proportion of a methyl ether of methylol melamine, said copolymer, butyral and methyl ether being at least partly inter-reacted. 14. A friction-calendered tracing cloth which consists essentially of a woven cotton fabric suitable as a base for tracing cloth impregnated with (1) a copolymer consisting of methyl hexyl carbinyl acid maleate and styrene, said maleate and styrene beingcopolymerized in a molal ratio between 1:1 and 1:2, (2) a minor proportion, based on said copolymer, of polyvinyl butyral and (3) a small proportion of a methyl ether of methylol melamine, said copolymer, butyral and methyl ether being at least partly inter-reacted.

HORACE WOOD, JR.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Great Britain June 8, 1937

Claims

1. A METHOD OF PRODUCING TRACING CLOTH WHICH COMPRISES IMPREGNATING A WOVEN COTTON FABRIC WHICH IS SUITABLE AS A BASE FOR TRACING CLOTH WITH AN ORGANIC SOLVENT SOLUTION COMPRISING (1) FROM 5 TO 30% BY WEIGHT OF A COPOLYMER CONSISTING OF A SECONDARY ALKYL HALF ESTER OF AN ETHYLENE A,B DICARBOXYLIC ACID SELECTED FROM THE GROUP CONSISTING OF MALEIC AND FUMARIC ACIDS, AND A POLYMERIZABLE VINYL COMPOUND HAVING THE STRUCTURAL FORMULA: R-CH=CH2, WHERE R IS SELECTED FROM THE GROUP CONSISTING OF A PHENYL, HALOGEN SUBSTITUTED PHENYL AND METHYL SUBSTITUTED PHENYL RADICAL, SAID HALF ESTER AND VINYL COMPOUND BEING COPOLYMERIZED IN A MOLAL RATIO BETWEEN 1:1 AND 1:2, (2) A MINOR PROPORTION, BASED ON SAID COPOLYMER, OF POLYVINYL BUTYRAL, (3) FROM 0.5 TO 5% BY WEIGHT OF A COMPOUND SELECTED FROM THE GROUP CONSISTING OF FORMALDEHYDE, PHENOL-FORMALDEHYDE RESINS, UREA-ALDEHYDE RESINS, ALKOXY ALKYL ALKYL MELAMINE RESINS, ALKYLENE POLYAMINES AND ALKYL MELAMINE RESINS, ALKYLENE POLYAMINES AND POLYGLYCOLS AND (4) AN ORGANIC SOLVENT FOR THE FOREGOING INGREDIENTS, SAID SOLUTION COMPRISING FROM 6 TO 32% BY WEIGHT OF SOLIDS; DRYING SAID FABRIC AND THEN FRICTION-CALENDERING SAID FABRIC.