US2335739A - Coated fabric - Google Patents

Description

Patented Nov. 30, 1 943 V l Tl' -D STATES PATENT. OFFICE I j 2.335.739 i i COATED FABRIC Merle H. Chamberlin, Newbmh Sig-11 i to E. I. du Pont de Nemours & Company; Wil-v I i. mington, Del., acorporation of Delaware No Drawing.

Application January 31, 1942, Serial No. 428,979

16 Claims. (Cl. 117-46) This invention relates to nitrocellulose coated sheets, including non-woven paper sheets and woven fabric sheetawhich contain a material which will discolor nitrocellulose.

In my copending application Ser. No. 416,601, filed-October 25,1941, there is disclosed and claimed a stain resistant'nitro'cellulose coated fabric which is surfaced .with a layer of either celluloseacetobutyrate'or cellulose acetopropionate. This material is resistant to staining by colored cosmetica foodstufis, etc.

In" the coated fabric industry the base fabric,

usually cloth or, paperJiS often dyed a color approximately the color of the coating which is to-besubsequently applied; The dyes employed are water-solubleanddo-notbleed when contacted with organic solvents which are employed in cellulose derivative compositions." When a 'paper' base is made from reclaimed rags which are usuallydyed, occasionally small quantities of anoil or spirit-soluble-dyefwill be carried over to the paper- -base. When a n'itrocellulose containingcompo sitioii applied over a base material containingonly tracs df oil or" spirit soluble, the dyestuff willbleed -'1'1p through thenitrocellulose coatingandthedye color-will appear on the surface of the coating, thus marring the appearance of the'finished'product. --This'is extremely objec- 'tionable'wliere the nitrocellulosecoating is of a shade lighter than'thedyestuif color. I

Also in'the dyeing of fabrics with water soluble dyesto be subsequently coated with organic solutions of nitrocellulose compositions the dyes employed frequently become contaminated with traces of oil or "spirit'soluble-dyestufis' which will remain on the fabric after dyeing and will bleed up through the nitrocellulose coating.

In the case of paper made from reclaimed dyed rags, it is not practical to extract the oil or spirit soluble dyestufl's before converting the rags into paper sheets and, therefore, such'paper has not plasticizers willalso discolor lightfcolored nitrocellulose coatings applied over such a paper base.-

This invention hasasa primaryv object, the, provision of a'simple and economical'method of preventing the discoloration of, nitrocellulose coatings applied overuapaper oriabric bases containing a materialwhich will discolor nitrocellulose, and doesnot'requirewany procedure'or' apparatus other than thatnowused-inithe coated fabric and paper industry. objective, as well as other important but subsidiary objectives will become readily-apparent to-' those skilled in the art-as the description of the invention pr'o'ceeds";

These objects are accomplished by *afpplyingfa' barrier coating of a cellulose acetopropionat'e or cellulose acetobutyrate ai'reuy ov'erthe fabric or paper base containing either spirit-broilsoluble dyestufl, rubber antioxidants .or; -a-bituminous plasticizer, and subsequently applying a nitrocellulose coatin'g over the barrier coat. N Thebarrier coating will not permit the" migration of'the nitrocellulose staining ina'terial'up tli'rou gfli 'fto' found widespread -use as a base for nitrocellulose coatings. These papers have been confined to black coatings which would not show the discoloration resulting from the contaminating dye- The paper stocks suitable for coating with the nitrocellulose.

The following description of the prefe bodiment is given by the "way'o'f illustration and not limitation; it beingund'er's'tood that the invention is not to belimited to this pre ferred'em- EXAMBLEI A woven fabric pound per 53 inch width and having a sateen weave was dyed with-an oil or spiritsoluble dyestuif. A plurality of coats of a cellulose acetopropionate coating of the following approximate composition was applied by means of a doctor knife. Base coating composition Per cent by weight Cellulose acetopropionatenu 18.75 Ethyl phthallyl ethyl glycollate 6.25 Ethyl mh 37.50 Ethyl aceta 37.50

Sufiicient coats of the above composition were applied to deposit 2 ounces per yard per inch width of the non-volatile components. The

method of preparing the above composition is well known in the art and further detailed description does not appear to be necessary. The

volatile solvents were expelled between each successive coat of the composition by passing the material through a heated chamber.

The material was then given a plurality of coats of the following composition:

Surface coating composition Per cent by weight Cellulose nitrate 14.10

White pigment 14.57 Castor oil 24.76 Ethyl alcohol 23.28 Ethyl aceta 23.29

The volatile solvents were expelled by passing the coated fabric through a heated chamber. The surface coating firmly anchored to the cellulose acetopropionate coating. Sufilcient surface coating composition was applied to deposit approximately 15 ounces of non-volatile compo- .nents per yard for 50 inch width. The coated EXAMPLE H The following composition has been-found satisfactory as barrier coats to be applied directly over a fabric or paper base containing an oil or spirit soluble dyestufl which is subsequently over coated with conventional plasticized nitrocellulose compositions:

Base coating composition Per cent by weight Cellulose acetobutyrate 18.75 Mixture of orthoand para-toluene ethyl sulfonamides 6.25 Ethyl alcohol 37.50 Ethyl ace 37.50

Exemma III A film deposited from the following composition is a satisfactory barrier to the passage of oil or spirit soluble dyestufl, rubber antioxidants and bituminous materials contained in paper or fabric sheet'material:

Bas'e coating composition Per centby weight Cellulose acetobutyrate 17.90

Zinc oxide 13.84 Mixture of orthoand para-toluene ethyl.

sulfonamides 6.92

Ethyl alcohol 30.67

Ethyl acetate 30.67

While in the preferred embodiment of this invention the barrier coat of cellulose acetopropionate or cellulose acetobutyrate is applied directly over the base material containing either an oil soluble dyestuff, rubber antioxidant or a bituminous material, it may be sandwiched in between two layers of cellulose nitrate coatings. This is particularly advantageous in commercial production when the cellulose nitrate coating is applied over a dyed cotton fabric or paper base in which the dye forthe fabric or paper dye was unknowingly contaminated with oil soluble or spirit soluble dyestufi and was not detected until a portion of the nitrocellulose coating had been 7 applied. A barrier coat of either the cellulose acetopropionate or cellulose acetobutyrate com-, position may be applied over the discolored nitrocellulose coating and a suflicient coating of additional nitrocellulose com'positon applied over the intermediate barrier coat to hide discolored areas since the barrier coat is usually unpigmented and does not conceal the stained areas.

In the preferred examples the barrier coat is a mixed ester of cellulose, such as cellulose acetobutyrate and cellulose acetopropionate.

. It is also to be understood if the base material containing the oil or spirit soluble dyestuif is to be coated on each side, it is necessary to apply the barrier coat on each side of the base material. Also if the sheet base material containing a nitrocellulose staining material is to be coated on one side only andto be stored for any length -of time in roll form where the coating is in direct contact with the uncoated side of the base material, it is desirable to apply a barrier coat on each side of the base material in order to seal in the nitrocellulose staining material and prevent contact with the nitrocellulose coating.

While the invention has been described with respect to a specific construction of a coated 'fabric, it will be readily-apparent to those skilled in the art that the invention can be utilized with any pyroxylin coated fabric construction or pyroxylin coated paper. There is no limitation to be placed upon the nitrocellulose composition which is applied over the barrier coat in accordance'with the teachings of this invention.

The plasticizer for the cellulose acetopropi onate or cellulose acetobutyrate is preferably one which does not have an afinity for the oil or spirit soluble dyestuffs, commonly used in the dyeingof fabrics or paper to form the baseof pyroxylin coated sheets. Plasticizers for thecellulose acetopropionate or cellulose acetobutyrate, other than those mentioned in the examples,

which ehave been found to besatisfactory for I the purpose of this invention are triethylene glycol dihexoate, dibutyl phthalate, dibutyl tartrate, triethylene glycol dicaprylate, tricresyl phosphate, tributyl phosphate and the dibutyl ester of sebacic acid.

It has been found that the resistance of the barrier coat to the passage of the nitrocellulose staining material is in proportion to the amount of plasticizer content present. ,It has been discovered that if the plasticizer content of the barrier coat is increased beyond 65% of the total amount of non-volatile components of the barrier coat, that it is not sufllciently resistant to the oil or spirit soluble dyestufl.

' In the preferred embodiment the nitrocellulose overcoating contains an oil or softener and a pigment. It has been found that the oil orspirit soluble dyestuffs, rubber, antioxidants, and bituminous plasticizers will discolor unpigmented, plasticized nitrocellulose films. Also these materials will discolor unpigmented, and unpla-sticized nitrocellulose films.

This invention will find great utility in the field of nitrocellulose coated fabrics and papers in using base materials which unknowingly become contaminated during the dyeing process with spirit or oil soluble dyestuffs which otherwise could only be used as a base for very dark or black shades. Also the invention will find reat use in coating papers containing nitrocel lulose discoloring materials such as rubber antioxidants, and bituminous materials. Where the dyed base material is unknowingly contaminated with oil soluble'dyestufi, it is not normally encountered until the first one or two coats of the cellulose derivative are applied at which time a layer of the barrier coat can be applied over the discolored coating and then the cellulose derivative coating applied over the barrier coat.

An advantage of this invention is that it allows the use of paper base material made from reclaimed rags which contains 011 soluble dyestufis fdr light colored pyroxylin coatings. A further advantage is that it permits the use of water soluble dyestufis which have become contaminated with oil or spirit soluble dyestufl for dyeing paper or fabric sheets which are to be subsequently coated with compositions containing organic solvents in which case the oil or spirit soluble dyestuflf does not bleed up to the surface of the coating.

It is apparent that many widely different embodiments of this invention may be made without departing from the spirit and scope thereof, and therefore, it is not intended to be limited except as indicated in the appended claims.

I claim:

1. A base material containing a nitrocellulose discoloring agent said base material having superposed on-at least oneside thereof a coatin of a mixed cellulose ester of a plurality of lower aliphatic acids, said mixed ester being characterized by its resistance to coloring by said agent and an overcoating of a nitrocellulose composition, said nitrocellulose composition being characterized in that it is susceptible to coloring by said agent. v 2. The product of claim 1 in which the mixed cellulose ester comprises cellulose acetopropionate.

3. The product ofclaim 1 in which the mixed cellulose ester is celluloseacetobutyrate.

4. A dyed fabric base material containing a ester of cellulose comprises cellulose acetobutyrate.

7. A dyed paper base material containing a nitrocellulose discoloring agent having superposed on at least one side thereof a coating of mixed cellulose ester of a plurality of lower aliphatic acids, said mixed ester being characterized by its resistance to color bysaid agent nitrocellulose discoloring agent said base material having superposed on at least one side thereof a coating of a mixed cellulose'ester of a plurality of lower aliphatic acids, said mixed ester being characterized by its resistance to coloring by said agent and an overcoating 01' a nitrocellulose composition, said nitrocellulose composition being characterized in that it is susceptible to color by said agent.

5. The product of claim 4 in which the mixed ester comprises cellulose acetoproplonate.

6. The product of claim. in which the mixed and an overcoating of a nitrocellulose composition, said nitrocellulose composition being characterized in that it is susceptible to color by said agent.

8. The product of claim v'7 in which the mixed ester of cellulose comprises cellulose acetopropionate. v I

9. The product of claim 7 in which the mixed ester of cellulose comprises cellulose acetobutyrate.

10. A dyed sheet base material containing a nitrocellulose discoloring agent said base ma- ;terial having superposed on both sides thereof a coating of a mixed cellulose ester of a plurality of lower aliphatic acids, said mixed ester being characterized by its resistance to coloring by said agent and an overcoatlng of a nitrocellulose composition, said nitrocellulose composition being characterized in that it is susceptible to coloring by said agent.

11. The product of claim :10 in which the mixed cellulose ester comprises cellulose acetopropionate.

12. The product of claim 10 in which the mixed cellulose ester comprises cellulose acetobutyrate.

13. A dyed sheet base material containing a nitrocellulose discoloring agent said base material having a first coating of nitrocellulose applied directly thereto, a second coating of a plasticized cellulose ester of mixed lower aliphatic acids composition superposed on the first mentioned coating, 9. third coating of nitrocellulose applied over said second coating, the said first and third coatings being characterized in I that they are susceptible to coloring by said discoloring agent. I

14. The product or claim 13 in which the 16. The product of claim 13 irrwhich the-plasticizer in the mixedester coat is less than per cent thereof.

MERLE H.