US2939200A - Fabric woven from coated yarns - Google Patents

Description

June 7, 1960 H. EWING ETAL FABRIC WOVEN FROM C(JATED YARNS Filed may 12, 195 4 PLASTICIZED POLYVINYL CHLORIDE CELLULOSIC YARN FIG.

m w H C L m V m w H m m m x CELLULOSIC YARN CELLULOSIC YARN PLASTICIZED POLYVINYL CHLORIDE FIG. 2

CELLULOSIC YARN COATED WITH PLASTICIZED POLYVINYL CHLORIDE FIG. 3.

United States Patent F FABRIC WOVEN FROM COATED YARN Henry Ewing and Alexander Henderson Gentle, Spondon, near Derby, England, assignors to British Celanese Limited, a corporation of Great Britain Filed May 12, 1954, Ser. No. 429,323

Claims priority, application Great Britain May 15, 1953 1 Claim. (CI. 28-80) This invention relates to fabrics and other textile materials, and especially to the production of fabrics of good fire-resistance.

The fabrics of the invention are formed from yarn having a relatively heavy coherent overall coating (preferably from 80 to 150% of the uncoated yarn weight) of a rubber-like, water-resistant, non-inflammable filmforming material, preferably comprising a chlorine-containing polymer, especially gelled plasticized polyvinyl chloride. By rubber-like is meant having at ordinary temperature a recoverable extension of at least 30%. Coated yarns of the kind specified are thought to be novel in themselves, and the invention includes such yarns. Preferably the yarn is a multi-filament yarn of heavy denier. It may, for instance, contain 500 to 4,000, e.g. 1,000 to 3,000, filaments of denier between about 0.5 and about 4, e.g. 1 to 2.5.

One of the objects of the invention is to provide a waterproof, substantially non-inflammable, fiexible sheet material combining high strength with relatively low weight per unit area. We considered that such a material might be obtained by coating a fabric woven from high-tenacity, continuous-filament yarns with a non-inflammable, water-resistant, film-forming material. (By high-tenacity is meant of tenacity at least 3 gms. per denier.) High-tenacity, continuous-filament yarns, however, do not readily adhere to such film-forming materials. This lack of adhesive properties was a source of considerable difficulty. It seemed desirable to use for the material of the fabric a material of low or negligible infiammability. Various condensation polymers which melt when heated, and especially nylon-6-6, do not readily propagate flame, but it was found particularly difficult to provide a fabric of such material with a firmly adherent coating of water-resistant, non-inflammable, filmforming material. High-tenacity regenerated cellulosic material presented somewhat less difficulty in respect of adhesion, but when coating was effected by any of the conventional fabric coating methods it was found necessary to apply a very heavy coating to obtain the desired fire resistance, and this resulted in a relatively stiff and heavy fabric. It was finally found that the desired object could be achieved by coating a high-tenacity, regenerated cellulose, continuous-filament yam with a dispersion of polyvinyl chloride in tricresyl phosphate, heating the yarn to gel the plasticized polyvinyl chloride (Le. to form it into a coherent non-sticky layer), weaving a fabric from the coated yarn and subjecting the fabric to heat and pressure so as to seal the interstices in the fabric.

Example 1 describes making a waterproof, substantially non-inflammable sheet in this way.

Example I The textile material was a yarn of regenerated cellulose Patented June 7, 1960 length. The filament strength of the regenerated cellulose was approximately 7 gms. per denier.

The film-forming material was a so-called P.V.C. paste, consisting of polyvinyl chloride dispersed in substantially the same weight of tricresyl phosphate.

The yarns were drawn in the form of a parallel sheet over a circumferentially-grooved furnishing roll, freely rotatable in a bath of the polyvinyl chloride paste, each yarn being accommodated in one groove in the roll. A doctor blade extending across the roll controlled the amount of paste taken up in the grooves of the roll. The yarns passed beneath this blade and thence partly round the roll. After leaving the roll they passed above an infra-red heater, which applied sufiicient heat to the travelling yarn to gel the coating of plasticized polyvinyl chloride. The yarn was then taken up under substantially constant tension. (The yarn required to form the warp of the fabric was taken up on a warp beam, and that required for the weft on individual bobbins.)

From the coated yarn a fabric was woven in a plain weave, but using two picks and two ends in place of one, and there being 30 ends and picks per inch, and both warp and weft consisting of the coated yarn. The fabric weighed 19.3 ozs./sq. yd., the weight of the uncoated yarn being 9.5 ozs./sq. yd.

The fabric was pressed for five minutes at a temperature of C.

In this way a supple, waterproof, fire-resistant material was made which was particularly suitable for use as the material for railway truck covers. The most suitable material previously found for such covers was a flax fabric having a heavy coating of a linseed oil-bauxite composition on both sides. The properties of a typical sample of railway truck cover material made of coated fiax fabric are compared in the table below with the properties of a material made for the same purpose according to the present invention. fabric is referred to as material A, and the material obtained by the process of the example is referred to as material B.

Property M atfria Mugrlnl It is preferred to use regenerated cellulose yarn obtained by the complete saponification of cellulose acetate yarn that has been stretched to many times its original length (i.e. 8 to 15 times) in a suitable stretch-assisting agent, e.g. moist steam or hot water, or that has been so stretched during a wet spinning operation. Yarn obtained in this way may have a tenacity within the range 3-7 gms. per denier, according to the degree to which the cellulose acetate yarn was stretched and the shrinkage effected in saponification or in an additional shrinking operation. The structure of regenerated cellulose yarn obtained in this way appears to be different from that of other kinds of high-tenacity regenerated cellulose yarn, e.g. high-tenacity yarn obtained by the cuprammonium or viscose processes. Nevertheless, high-tenacity yarn of regenerated cellulose made by such processes may also be treated in the same way as the saponified cellulose acetate yarn referred to.

In the table, the coated flax As the film-forming material for coating the yarn, it is preferred to use polyvinyl chloride plasticized with tricresyl phosphate. Other fire-resistant plasticizers for polyvinyl chloride can be used instead of or in addition to tricresyl phosphate. Such plasticizers include other liquid aromatic phosphoric acid esters, e.g. trixylenyl phosphates. Less fire-resistant plasticizers, e.g. dibutyl phthalate, di-Z-ethyl hexyl phthalate and other esters of dicarbonylic acids, especially phthalic acid, may also be used, but at some sacrifice of fire-resistance in the product. The nature and amount of the plasticizer should be suiticient to impart to the polymer forming the basis of the film-forming material some degree of rubber-like elasticity. Instead of polyvinyl chloride, other polymers containing a relatively high proportion of chlorine and capable of exhibiting the desired rubber-like elasticity (if necessary when compounded with a suitable plasticizer) can be employed. Examples of such polymers are copolymers of vinyl chloride with a minor proportion (5-15 of the total of the copolymer weight) of vinyl acetate, copolymers of vinyl chloride with vinylidene chloride, and chlorinated polythenes. Chlorine-containing polymers derived from dienes, e.g. polychloroprene, chlorinated rubber and rubber hydrochloride are less suitable.

In coating the yarn with the film-forming material, it is greatly preferred to employ that material in the form of a paste or dispersion with the plasticizer, and to form the coating into a substantially homogeneous, continuous layer round each yarn by a so-called gelling process, comprising heating the coated yarn. By this method a relatively heavy coating of the film-forming material can be obtained without the necessity of making two or more successive applications of film-forming material, and without the use of any volatile liquid. The weight of the coating may range from about 40 to about 150% based on the weight of the yarn. We have found that amounts between about 80 and 150% of that weight, e.g. from 95-110% thereof, give satisfactory results in most cases. It will be appreciated that in the fabric, unless (as described below) an additional coating has been applied after weaving, the weight ratio of coating to fabric will be the same as that of coating to yarn.

For the hot-pressing operation, the best results have been obtained by pressing the fabric for several minutes between the heated plates of a press. Heat and pressure can, however, be applied by other methods, e.g. by a calendering operation.

The method of weaving a fabric from yarn coated with a plasticized, rubber-like, water-resistant, non-inflammable, film-forming material, and subjecting the fabric to heat and pressure so as to cause the film-forming material to seal the interstices in the fabric, enables non-inflammable fabrics to be made which are supple, and in relation to their weight very strong, especially when hightenacity continuous-filament yarns are employed. As indicated above, specially advantageous results are obtained when high-tenacity regenerated cellulose continuous-filament yarns are employed with plasticized polyvinyl chloride. The method described may be applied with some advantage to continuous-filament yarns of materials other than regenerated cellulose and cellulose acetate, e.g. yarns of natural silk, of nylon-66 and other polyamides such as nylon-6 and nylon-610, of polyethylene terephthalate, of polyacrylonitrile, of copolymers of acrylonitrile with vinyl chloride or vinylidene chloride, and yarns of glass fibre. The method described is of advantage also when the yarn is a stable fibre yarn made, for instance, of any of the fibre-forming materials referred to above or of animal fibres such as wool.

The method described can be used in making waterproof, substantially non-inflammable fabrics for various purposes other than for truck covers. Thus, for example, the method may be used in making fabrics for fireresistant clothing and conveyor belting fabrics, and driving belts, including spindle-driving tapes.

If desired, an additional coating of the film-forming material can be applied to one or both sides of the fabric. This can be done, for instance, after weaving and before the hot pressing operation, the gelling of the composition of the further coating then being effected during the pressing operation. Additional coatings of film-forming material can also be calendered on to the fabric after pressing, or preformed sheets of the film-forming material can be bonded to one or both sides of the fabric. Two or more layers of the fabric woven from the coated yarn can also be bonded together, e.g. by additional layers of the film-forming material, and additional layers of that material may also be provided on one or both sides of the laminate.

For some purposes it is not essential that the fabric should have the degree of resistance to penetration by water that is imparted to the fabric when the interstices between the yarns are sealed by the film-forming material. In making fabrics in which the interstices are not so sealed, the hot-pressing step may be omitted and/or the fabric construction may be more open. For example, the number of picks and/or of warp ends per inch may be reduced to such an extent that any hot-pressing operation does not result in the interstices being filled. The fabric may be plain-woven, or special constructions adapted to ride as the film-forming material. Very useful sheet materials can also be made from cellulose acetate yarns with the film-forming material, especially gelled plasticized polyvinyl chloride. When high strength is required have been obtained from cellulose acetate yarn in which i the acetyl value is between 51 and 54%.

High specific adhesion between the film-forming material and the yarn does not appear to be essential when give large spaces between the threads may be adopted. Thus, for example, the coated yarn may be woven to form a leno fabric. Alternatively, the fabric may be formed from the coated yarn by knitting, e.g. by warp knitting or circular knitting, or by netting. To avoid sealing the interstices, the weight of the coating providedround each yarn may also be decreased, but this weight should in general not be less than about 25% of the weight of the yarn, and is preferably at least 50%. It may, of course, be much greater, e.g. between 50 and of the yarn weight. By forming fabrics from the coated yarns (e.g. yarns of high-tenacity regenerated cellulose coated with polyvinyl chloride plasticized with a phosphate plasticizer) without sealing thcinterstices between the yarns, we have obtained fabrics of excellent fire-resistance, of low water-absorption, but not resistant to penetration by water under pressure, of good flexibility and suppleness, and of high tear-strength.

For some purposes, for instance for driving-belts and tapes, high lateral strength is unnecessary. For such purposes fire-resistant, waterproof fabrics can be made by bonding together the coated yarns in parallel alignment without the use of a weft, or with weft yarns very widely spaced apart. The bonding can be effected bypassing the warp of coated yarns through a hot calender or by pressing the warp while hot in a press of the kind used in making rubber belting. The fabric should preferably be cooled before removal from the press, and the operation may be carried out by raising the warp of coated yarns to a temperature slightly above that required to effect a satisfactory bond under the pressure available, and introducing the hot length of warp into the press, which is kept cool. Laminates can be made by bonding together a plurality of layers of weftless fabric made as described. By assembling the fabric layers so that the,

threads in one layer run at an angle to those in the next layer, laminates of good lateral tenacity and tear-strength can be obtained. It is possible to make tubular laminates by winding two or more layers of the weftless fabric or of the warp of coated yarns round a mandrel and effecting the bonding on the mandrel. Tubular laminates so formed can, if desired, be slit to form a sheet, and when the yarns in successive layers run at an angle to one another, the line along which the tube is slit may or may not be parallel to one set of yarns. Very heavy sheets can be made by flattening the tubular laminate and bonding all layers together, instead of slitting the tube.

A further method of making fabrics according to the invention is by bonding together a random assembly of relatively short lengths of the coated yarn. The yarn may, for example, be coated as described above, and, after gelling the coating, the yarn may be cut up into the desired-short lengths, which may range, for instance, from half an inch to several inches. The bonding together of the lengths of yarn may be effected in a press or by a hot calendering operation, in which, if desired, the coated yarns may be supported between two layers of a fabric to which they do not adhere, these fabric layers being subsequently stripped from the bonded fabric. Very openwork fabrics having a pleasing, irregular design can be obtained by the methods described. Such fabrics, where the structure is very open, seem likely to be useful as camouflage materials. They may also be used for decorative purposes, for instance, when exposed beneath a sheet of transparent material such as a glass table top, or bonded to two sheets of transparent or translucent thermoplastic material in making lampshades and the like.

The following examples, in which all the parts are by weight, further illustrate the invention.

Example 2 The yarn to be coated was as specified in Example 1. The film-forming material was a dispersion of ,the following composition:

50 parts of polyvinyl chloride;

20 parts of a mixture of phthalates of secondary alcohols containing 7 to 9 carbon atoms, obtained by hydration of an olefine cut;

20 parts of tricresyl phosphate;

10 parts of di-(methylcyclohexyl) phthalate.

The application of the film-forming material and the subsequent gelling of the coating were effected as described in Example 1.

From the coated yarn a fabric was woven in a plain weave, but using two picks and two ends in place of one, and there being 30 ends and picks per inch, and both warp and weft consisting of the coated yarn. The fabric weighed 19.5 ozs./sq. yd., the weight of the uncoated yarn being 9.5 ozs./sq. yd.

The fabric obtained was supple and of good tenacity and tear-resistance in both directions. Its waterabsorption was low, and although water was able to pass between the interstices of the fabric, immersion of the fabric in water did not result in as substantial a reduction in the tenacity as occurred when a fabric of the regenerated cellulose coated with the same mixture after weaving was subjected to the same test.

Example 3 The process was carried out as in Example 2, but using as the textile material a continuous-filament cellulose acetate yarn of total denier 1,200, filament denier 2.5, and twist 1.5 turns per inch.

It will be understood that the fabric obtained in this example can be subjected to a hot pressing operation, e.g. at a temperature of C., to seal the interstices, if a substantially waterproof fabric is desired.-

Example 4 The process was carried out as in Example 3, except that the yarn was of 1,600 total denier, 1.6 filament denier, and 2.5 turns per inch. The filament tenacity was 4 grns. per denier. The fabric was of higher strength than that of Example 3.

Example 5 The coated yarn was as described in Example 2. A warp of this yarn was drawn through a hot calender with adjacent warp yarns in contact, and in this way the yarns were bonded together to form a weftless fabric. The fabric was waterproof, fire-resistant, supple, of high tenacity in a direction parallel to the run of the yarn, and of good abrasion resistance. Strips of the fabric were suitable for use as driving-tapes for textile apparatus.

Example 6 The coated yarn was as described in Example 3. This yarn was cut into one-inch lengths. The cut yarn was fed into a calender in such a way as to produce a random arrangement of overlapping yarn lengths. During passage through the calender, the yarn lengths were bonded into an openwork fabric of irregular pattern. The fabric was of excellent fire-resistance, of low water-absorption and of considerable strength both longitudinally and laterally.

Example 7 The process was carried out as described in Example 5, except that the yarn was a cellulose acetate yarn as specified in Example 4, and the dispersion with which the yarn was coated had the following composition:

50 parts of polyvinyl chloride; 20 parts of di-(3,5,5-trimethyl-n-hexyl)-phthalate; 10 parts of di-(methylcyclohexyl) phthalate.

Although it is preferred in making a weftless fabric to coat the yarns as a separate operation before bonding them together, we have found that quite good results are also obtainable by effecting coating and bonding substantially simultaneously, for example by feeding the coating composition together with the yarns into a hot calender.

The cellulose acetate of Examples 3, 4, 6 and 7 was of acetyl value between 52 and 54%.

The accompanying diagrammatic drawings illustrate by way of example fabrics made according to the invention.

In the drawings:

Figure 1 is a part sectional view in perspective of a weftless fabric made according to the invention by bonding together in parallel alignment yarns of cellulosic material each having a heavy continuous coating of plasticized polyvinyl chloride.

Figure 2 shows in sectional elevation a laminate made by bonding together two weftless fabrics of the kind shown in Figure 1, in such a way that the yarns in the one are perpendicular to the yarns in the other.

Figure 3 shows a fabric made by bonding together randomly arranged short lengths of cellulosic yarn having a heavy continuous coating of plasticized polyvinyl chloride.

Having described our invention, what we desire to secure by Letters Patent is:

Flexible sheet material of good fire and water-resistance and high strength-weight ratio, said material comprising a woven fabric of coated yarn, each end of said References Cited in the file of this patent UNITED STATES PATENTS 1,673,797 Brown June 19, 1928 8 Neville et a1 July 9, 1940 D'Orio Nov. 29, 1949 Whalen Sept. 19, 1950. Philipps Sept. 4, 1951 Howald et a1. Oct. 16, 1951 Foster Dec. 2, 1952 Rodman Nov. 29, 1955 Schoenberger July 24, 1956 Southwell Nov. 6, 1956

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