US2390780A - Process of making coated textile materials and the articles produced therefrom - Google Patents

Description

Patented Dec. 11, 1945 PROCESS OF MAKING .COATED TEXTILE MATERIALS AND THE ARTICLES DUCED THEREFROM Ralph T. K. Cornwell, Fredericksburg, Va", as-

signor to Sylvania Industrial Corporation,- Fredericksburg, Va., a corporation of Virginia No Drawing. Application October 2, 1943,

Serial No. 504,781

4 Claims. (Cl. 117-73) The present invention relates in general to waterproof textiles. More particularly, it relates to waterproof textiles of the class of oil cloth,

artificial leather, raincoats and the like, and to a process for producing the same.

Heretofore, in the manufacture of waterproof textiles, such as oil cloth, artificial leather, raincoats, and the like, it has been customary to apply a multiplicity of coatings to a fibrous sheet material, such as fabric, felts and paper. The trade would prefer to avoid the use of such multiple coatings but heretofore this has not been possible because (a) the fibrous materials, such as textiles, felts and papers are extremely porous, and the-first two or three coatings appliedtend merely to sink into the sheet without forming a film thereover; (b) such fibrous materials are characterized by having a substantial nap, the fibres of which tend to protrude through the coatings-and impart an uneven surface to the product; and due to the porosity, certain pin holes continue to exist even after the application of two or more coatings. Accordingly, the trade has found that these disadvantages can be overcome only by the application of a multiplicity of coatings, it being common in the trade to apply as many as seven or eight coatings in the manufacture of oil cloth, artificial leather and shoe fabric. It is obvious that the application of such a large number of coatings which must be separately dried is expensive, time consuming, and necessitates the use of a large amount of labor and equipment.

It is a general object of the present invention to provide a fibrous material with a waterproof and/or moistureproof coating which will tena- 'cious1y adhere to the material even during immersion in water for an unlimited length of time. It is another object of the present invention to provide a coated textile, of which the coating will be non-tacky, flexible and waterproof and strongly adherent.

A further object of the present invention is PRO- the sized textile and the moistureproof top coating to anchor the top coating to the sized textile. In the now preferred embodiment the textile is sized with an alkali-soluble water-insoluble cellulose ether, the anchor coating is a lacquer containing as the film-forming base a urea-formaldehyde resin, and the top coating .consists of a cellulose derivative, a plasticizer, a wax and a wax blending agent.

The invention accordingly comprises a process having the steps and relation :of one or more of such steps with respect to each ofthe others, and an article of manufacture possessing the features, properties and the relation of elements which will be exemplified and hereinafter described and the scope of the invention .will be indicated in the claims.

By the term water resisting is meant the ability of the coating material to remain adhered to the base sheet during immersion in water for 'an unlimited period of time.

to provide a simple and eflicient method of applyinglsa waterproof coating to n'brous sheet materia Other objects of the invention will be apparent to those skilled in the art from the following detailed description.

According to the present invention, there is provided a 'multi-coated fibrous sheet material comprising a layer of textile sized with an alkalisoluble water-insoluble celluiosic material and having a moistureproof top coating, and a water- 5 The textile material The sizing composition The sizing composition comprises in general an aqueous alkaline disperslon of a non-fibrous cellulosic colloid, such as the alkali-soluble waterinsoluble cellulose ethers as a class, such, for example, as alkyl cellulose ethers, hydroxy-alkyl cellulose ethers, and carboxy-alkyl cellulose ethers; also, natural or degraded cellulose dissolved in inorganic or organic cellulose solvents, such, for example, as alkaline zincate and alkaline stannate solutions, sodium hydroxide, alkali metal perchlorates, cuprammonia, quaternary ammonium bases, and the like. Also, there may be used'viscose which is a solution of cellulose xanthate dissolved in aqueous sodium hydroxide solution. The use of the alkali-soluble water-insoluble cellulose ethers is preferred over the other cellulosic' colloids because they give stronger films than the solutions of natural or degraded cellulose and they do not require desulfurization as is necessary when viscose is used.

The sizing composition may contain optional ingredients, such, for example, as pigments, dyeresisting intermediate coating disposed between stuffs and mineral fillers, flreprooflng agents.

plasticizers; and the like. The textile material is sized by spraying, padding, backfllling or otherwise coating and/or impregnating the textile with the composition after which the cellulosic colloid is coagulated on the textile by tpieating the textile with a coagulant of the colloid, such, for example, as an aqueous solution of an acid, an acid salt or an acid gas. When using the cellulose ethers, they may be coagulated additionally by hot water. After the cellulosic colloid is coagulated on the fabric, it may be washed, soured or dried preferably while maintaining the textile at a predetermined width. When penetration of the textile is not necessary as in making a product coated on oneside only, the sizing composition is applied by backfllling, using a composition of high viscosity to retard penetration and to cause a filming-over or window-paning" of. the spaces between the yarns or fibres. and/or after coagulation the sized textile is calendered or passed between doctor blades to lay the nap fibres into the size.

When a degraded cellulose ether or a degraded cellulose is employed as the size, the dried sized textile is preferably submitted to a calendering operation or ironing at an elevated temperature. such, for example, as 50 to 100 C. The application of heat and pressure in this manner serves two purposes, (a) to smooth the fabric (b) to cause a substantial flow of the cellulosic colloid. While such degraded cellulosic colloids have been I heretofore considered by those skilled in the art,

as non-thermoplastic materials, nevertheless, it has been found that they exhibit a substantial thermoplastic flow when subjected to heat and pressure. This novel characteristic is taken advantage of in the present invention tolay' the nap fibres and to smooth the surface of the fabric whereby one is enabled to produce an impermeable and waterproof material by the application of only two coatings upon the sized and calendered textile. The textile is now ready for ,the

application of the i'ntermediateflor anchor coating.

The anchor coating The film-forming agent used in the anchor coating is a film-forming water-resisting material selected from'the class consisting of drying tor-oil-rnodifled-alkyd, and soy bean-modified alkyd resins; among the thermosetting resins there may be used phenol-formaldehyde resins, urea-formaldehyde resins, melamine-formaldehyde resins. and the like; and among the syn thetic rubbers there maybe used co-polymer of butadiene and styrene, e. g. Buna-S," polymer of ehloroprene, e. g. neoprene, co-polymer of isobutylene and buta-diene, e. g. butyl rubber, polvmer of ethylene dichloride and sodium tetrasulflde, e. g. Thiokol"; also halo enated natural rubber and the product of treating rubber with stannic chloride e. g. Pliolite," and the like. However. in the now preferred embodiment, the film-f rming agent in the anchor coating is a thermosetting resin in the thermoplastic heathardenable state.

Before 5 ing have been discovered, for example, the anchor coating may be obtained by (a) applying the synthetic resins to the sized textile from an aqueous solution containing either the individual compounds such as urea and formaldehyde, which will condense, upon heating with an acid catalyst, to form the resin, or containing a water-solu-ble intermediate condensate of the resinforming compounds, e. g. dimethyiol urea, the condensate being polymerized on the textile by heating to form a water-resisting non-tacky resin, the top coating being subsequently applied; (b) by applying to the textile, an organic solution comprising. an intermediate condensate of the resinsforming compounds which is tacky and soluble in organic solvents, the polymerization being continued on the textile until the coating is tack-free and water insoluble, the top coating then being applied.

The foregoing heat-hardenable resins are added to the coating solution in the incompletely polymerized heat-hardenable state, which means that they are capable of later being furtherpolymerized or hardened to a tack-free, substantially insoluble stage while included in the coating, for example, of the magnitude of about 0.0001 of an inch in thickness, by the application of heat and/or a catalyst for a period of not longer than several minutes and at a temperature not exceeding C. The heat-hardenable resins are cured to give products which are nontacky and substantially insoluble in water or the organic solvents used in the top coating. At the same time, they do not embrittle the coating but enable it to remain soft and pliable and capable 40 of undergoing shrinkage and swelling as the moisture content of the hydrophilic pellicle changes with variations in atmospheric humidity.

The hardening agent for the heat-hardenable resin may comprise any material which tends to accelerate the polymerization or hardening of the resin, as, for example, by the release of acid upon the application of heat. Among the hardening coating composition is preferablyof the plasticizing resin type, for example, aresin of the soft type such as polymerized unsaturated hydrocarbons, for example, polymerized isobutylene, which is commonly sold under the trade name Vistanex, or soft alkyd resins. In addition to the plasticizing resins, or in place thereof, organic plasticizers maybe employed such as dibutyl sebacate, dibutyl phthalate, tricresyl phosphate, cyclohexyl butyl phthalate, and the like, or mixtures of these plasticizers.

There may be added to the intermediate or anchor coating certain optional ingredients, in particular a secondary film-forming agent, a moistureprooflng agent, such as a wax blending agent, and slip agent. Slip agentsin the anchor coating are advisable when the pellicle has to be rewound before application of the top coating thereon.

7 The secondary film-forming base of the anchor The top coating The top coating comprises, in general, a filmforming moistureproof material, but if the filmforming material is not inherently moistureproof or sufliciently flexible there is added a moistureproofing agent, a plasticizer and, optionally, a

blending agent. The film-forming base of the top coating may comprise (a) film-forming organic-solvent soluble cellulose derivatives as a class, among which may be mentioned cellulose nitrate, cellulose acetate, ethyl cellulose, benzyl cellulose and the like; or (b) film-forming thermoplastic synthetic resins as a class, such, for example, as the resin resulting from the reaction of polyhydric phenols with aliphatic polyhalides, polymers of esters of acrylic acid and methacrylic acid, polyvinyl resins and the like, in particular a copolymer of vinylidine chloride and vinyl chloride; or (c) drying oils and drying-oil-modified resins, or a mixture of theseclasses of bases; or (d) natural and synthetic rubber and rubberlike materials, such as halogenated rubber,-rubber hydrohalides, cyclizedrubber derivatives, and the like.

In the now preferred embodiment the filmforming agent employed as the top coating comprises nitrocellulose combined with a plasticizer and a moistureprooflng agent.

In the top coating composition there may be employed a compatible plasticizer such, for example, as a soft alkyd resin or a non-volatile organic plasticizer, such, for example, as tricresyl phosphate, dibutyl phthalate, cyclohexyl butyl phthalate, dibutvl sebacate, and the like.

The moistureproofing agent may comprise a high-melting wax or a wax-like material. A high melting paraiiin wax is preferred for this purpose, that is, a paraflin wax melting between 62 and 65 C. is preferred, although other waxes and wax-like materials may be used, for example, ozokerite, ceresin wax, carnauba wax, and the like.

If desired, a suitable wax-blending agent may be added to the coating. As wax-blending agents, there are used substances which are characterized, in general, by a low melting point and a solubility in both hydrocarbon solvents and hydroxyl-containing solvents and by compatibility with molten paraflin wax, for example,

ester gum, a blown vegetable oil, wax-free dammar, japan wax, and castor oil phthalates.

The foregoing ingredients are suitably dis- I solved in a solvent or a mixture of solvents for all of the materials present. Suitable solvents are mixtures of aromatic hydrocarbons, alcohols and esteqs, such as xylene and butanol, or toluene and butyl acetate.

Generally speaking, the organic solvent or both'the intermediate coating and the top coating is evaporated at an elevated temperature and when a moistureprootlng wax is present in either of the coatings, the temperature employed is preferably above the melting point of the particular wax employed.

There maybe added to the topcoating a suitable slip-inducing agent which is added in accordance with well-known practices 'to enable one. finished sheet to slide over another when stacked. Suitable 'slip agents-are, for example, any comminuted solid,which is insoluble in the ingredients of the anchor coating, such, for example, as starch, talc, zinc oxide, calcium carbonate, and the like.

By way of explanation of the invention and not in limitation thereof, the following specific examples of an anchor coating composition for use in the production of a moistureproof waterproof article of the present invention will be given;

Example I.A cotton fabric is first wet with on aqueous solution containing /a% of Tergitol.

After squeezing the wet fabric by means of a water mangle, the wet fabric is coated on both sides with an aqueous alkaline solution of a hydroxy ethyl cellulose ether containing 7% of cellulose ether and 7% of sodium hydroxide, the solution havinga viscosity of 9 compared to pure glycerine. The cellulose ether is coagulatedon the fabric by passing it into a aqueous solution of sulfuric acid. It is then washed in water and treated with a solution of /g% soda ash, washed, and then treated with acetic acid solution to neutralize any residual alkali. Thereafter the fabric is plasticizedwith an aqueous solution containing from 3 to 10% monoethanol-- amine sulfamate. The material is then dried on a tenter frame to a desired width. In the dried product the percent of plasticizer on the weight of the dry cellulose ether is from to The intermediate or anchor-coating composition is prepared by mixing together the following substances:

Film-forming agent: 1 Parts Urea-formaldehyde butanol ether resin 39 Plasticize'r:

Alkyd resin 20 Hardening agent:

Maleic acid 10 This composition is dissolved in a'mixture of toluene, xylene, butyl alcohol and butyl acetate,

and after application to the dried sized textile, the solvent is evaporated at an elevated temperature, for example, from 75 to 98 C. During the evaporation of the solvent, the heat causes a further polymerization or hardening of the thermosetting resin to the insoluble stage and causes the coating to become firmly anchored to the textile so that it will not blister when immersed in water.

The fabric bearing the anchor coating is then coated with a composition comprising:

Film-forming agent: Parts Nitrocellulose (5-6 see.) 30

Plasticizers: I

Dibutyl sebacate 13 Alkyd resin (Beckaclte") 25 Moistureproofing agent:

Paraffin wax .(M. P-. 67 C.) 5 Wax blending agents: Esterifled Congo gum 5 Rapeseed oil 0.5

From 10-20 parts of this composition are dissolved in-200 parts of a mixture of 70 a,v toluene, 15% ethyl acetate and 15% butyl acetate. This solution is then applied to the sized textile bear ing the anchor coating and the solvent is evap= orated at an elevated temperature, for example, from 75 to9 89 .C., that is, above the melting point of the wax.

Example II.The process of Example I is repeated'using, instead of the cellulose ether solution, a solution formed by dissolving ground woodpulp in an aqueous alkaline solution of sodium zincate containing an excess of sodium hydroxide, the solution being effected by cooling the mixture-to about 8 C. with cracked ice, stirring and warming. The solution thus produced is then applied by back-filling to one side of a textile felt, the cellulose coagulated immediately and the alkali neutralized by means of an acid coagulant, after which the felt is washed and dried. The dried felt is then calendered whereby the surface is rendered smooth and the nap fibres coating consisting of Saran (a co-polymer of 80' parts of vinylidine chloride and 20 parts of vinyl chloride) dissolved in-suitable solvents, such, .for example, as a warm mixture of toluene and dioxane or a mixture of dioxane and methyl ethyl ketone. The product thus produced will be found to be highly moistureproof and resistant to loosening of the coating when the felt is soaked in water. The product thus serves-admirably as a floor covering, artificial leather and the like. It should be noted that in the second example no moistureproof wax is employed either in the anchor coating .or in the top coating because the Saran is itself highly moistureproof and water-resisting.

Since certain changes in carrying out the above process and certain modifications in the composition which embody the invention may be made without departing from its scope, it is intended that all matter contained in the above description hydrophilic alkali-soluble cellulose ether insol-' uble in water; coagulating said cellulose ether to form a coating and thereafter applying pressure to said cellulose-ether-coated fabric while the coagulated cellulose ether coating is in a wet gel state to cause the coating to flow and lay the nap;

I applying to said coated fabric an intermediate anchor coating comprising a hydrophobic thermosetting synthetic resin in an intermediate stage of polymerization dissolved in an organic solvent, said resin being selected from the-group consisting of phenol-formaldehyde resins, urea-formal- .dehyde resins and melamine-formaldehyde resins; said cellulose ether coating preventing penetration of the fabric by said resin solution; thereafter evaporating the organic solvent and continuing polymerization of the resin to give a nontacky water-insoluble coating; applying to said intermediate coating a moisture-proofing composition comprising a film-forming cellulose compound dissolved in a volatile organic solvent, said cellulose compound being selected from the group consisting of cellulose ethers and cellulose esters; and evaporating said last-mentioned organic solvent to form a top coating; said intermediate coating anchoring said top coating and the cellulose ether coating anchoring the intermediate coating to the fabric, whereby the various coatings tenaciously adhere to the fabric without cracking or peeling therefrom.

2. The process recited in claim 1, wherein the top coating comprises a plasticizer and a moisture-proof wax.

4o 3. A flexible, water-proof fabric made in accordance with the process defined in claim 1.

4. A flexible, water-proof fabric made in accordance with the process defined in claiml, in which the top coating comprises a plasticizer and a moisture-proof wax.

RALPH T. K. CORNWELL.