US2370946A - Textile fabric - Google Patents

Description

Mmh 6, 1945 D. FINLAYsoN :a1-AL4 TEXTILE FABRIC Filed Nov. 25, 1943 FIG. l

n V I I v F/Gz INV ENTOKS 7m W AvromlEY-S Patented Mar. v6, 1945 UNITED I STATES ,PATENTOFFICE TEXTILE FABRIC Donald Finlayson and Harry Crawshamspondon,

near Derby, England, assignors to British Celanese Limited, London, England, a company I of Great Britain Appuetimi November 25', 1943, serial No. 511,718

e AIn Great Britain November 19, 1942 (ci. zii-so) i example a i--shaftv satin, the warps being ar- 17 Claims.

This invention relates to textile fabrics yand is especially concerned'with woven fabrics that are rendered suitable for electrical insulating purposes' by` treatment with avdrying 4oil or other insulating varnish.

Fabrics of this character are generally required to combine extreme thinness with a high degree of strength, for which purposes fine yarns of high .suitableffor oiling or varnishing for use, for example, as an electrical insulating fabric comprises in both warp and weft, yarns of great ten-l sile strength-and low extensibility and yarns of relatively low strength and high extensibility woven together in such a way that the yarns of low extensibility are not interlaced in any substantial degree, and preferably not at all, with other yarns of the same kind but depend entirely or almost entirely for their maintenance in the fabric structure on the presence of the yarns of high extensibility. When a fabric of this kind is treated withan insulating varnish it is found to possess -a muchhigher resistance to tearing then a fabric of similar weight woven from the stronger yarns alone, apparently because there is no tendency for the stronger yarns, not being interlaced with one another, to cut intoone another and so localise .the strains on the yarns when the fabric is subjected to a tearing action.

In order to produce the desired effect on the fabric, that the low extensibility yarns-should not interlace with one another, many dierent arrangements f the ,two lkinds of yarn inthe warp and weft are possible, with corresponding systems or patterns of weaving. The simplest arrangement is a plain weave in which both warp and weft consist of the stronger yarnsalternating one and .onewith the more extensible yarns. Itis often more convenient. however, in the operation of weaving, to'insert picks of the same kind of yarn-in` pairs so that'the yarns of the weft alternate two and two. .In this case some other form ranged to alternate one and one.

In such an arrangement, all thelthrewads of one ofthe two warpsheets are of one kind for two successive picks and of the other kind for the next two picks and so on, the threads of the other sheet being always mixed. The effect required for the pur- 1 pose of the present invention can thus be obtained by causing the weft picks to alternate two and two, as stated above, the weft inserted at each pick being different in kind from the thread of which the one warp sheet\whollyv consists. In

both of the fabrics mentioned above, not only are the yarns of low extenslbilitynot interlaced with one another, but thel same is also tru'e of the yarns of high extensibility, the coherence of the fabric depending upon the interlacing of the warps of onefkind of yarn with the wefts of the other. Many other arrangements are also possible in which each of the two kinds of yarn does not interlace with its.own kind but depends on yarns of the other kind to hold it in the fabric.v Y

Itis particularly convenient to employ as .the stronger yarn in the fabric continuous lament yarns. of regenerated cellulose of high tenacity,

for example a tenacity in excess of about 2 grams per denier, accompanied Iby a low extensibility, e. g. of the order of 8% or less, the extens1bility Y generally' varying inversely with the tenacity ,achieved-,f Such high tenacity yarns 'may be made. for example, by the complete saponication of yarns of cellulose acetate or lother organic ester of cellulose that has been stretchedto a considerable extent while in asoftened condition, for example in the presence ofy wet or saturated steam or hot water as described in U. S.'Patents Nos. v

2,142,717 and 2,142,722. Again, high tenacity yarns of an organic ester of cellulose, which may saponiiledhigh tenacity cellulose ester'materialssubsequently be saponifled', can also be made by wet-spinning processes carried out` under such conditions that the materials are drawn down considerably as they are extruded, for example by several hundred percent ofthe length they would have if extruded freely and vwithout; stretch. Again, regenerated cellulose `yarns of high tenacity can alsobe made directly by spinning solutions of viscose or cuprammonium cellulose under suitable conditions, for 'example under such condi' tions that a considerable stretch is effected. AAmong othermaterials of which the' stronger yarns in the fabric may be composed are un.-

efthe kind referred te above and cellulose ether 0f waive than a plain weave must be adopted, for N5v materials' that in their, manufacture have bility of'about 15% or somewhat subjected to similar stretching processes for ensuring high tenacity.'

Any suitable fine yarn having a relatively high degree of extensibility, as compared with the high-tenacity yarns, may be employed as the more extensible yarn; e. g. in-association with high-tenacity lyarns having an extensibility of 8% or less, low tenacity yarns having an extensibility of 12-20% or more may be used. Thus, for

example, any of the types of yarn mentioned above as being capable of having a high degree of strength imparted to them by stretching them t weil as in the stronger yarn it is preferablethat the yarn should consist of continuous filaments,

' as from such yarns thinner fabrics of a given weight may be produced than vfrom yarns consisting of or containing staple lengths of fibre.

As typical of the high-tenacity low-extensibility yarns of regenerated cellulose previously described may be mentioned a continuous filament' in or run through a hot tower for an appropriate period.

The following is givenas an example of a fabric in accordancewith the present inven-v tion z Example The warp bf the-fabric comprises yarns of 30 denier of continuous filaments made by stretching continuous filaments of cellulose acetate and subsequently saponifying substantially completely the stretched yarn. These yarns alternate with .yarns of 45 denier made of unstretched and unsaponied cellulose acetate filaments, the two kinds of yarn alternating end and' end in the warp. Similar yarns are employed in the weft but in this case the picks of weft alternate two and two instead of one and one. The warp and weft are woven together to form a 4-shaft satin fabric with 100 ends per inch in the warp and 140 picks per inch in the weft.I The fabric so produced is treated with an insulating varnish hav,-` lng as its basis a glycerol/ phthalic-anhydride resin which has been modified with linseed oil, and containing about 60% 0f the modified resin together with ahydrocarbon thinner.

The fabric is run through a bath of the varnish and drawn vertically upwards, as it leaves the yarn made from cellulose acetate filaments by.

stretching .such filaments in the presence of wet steam to about'l ten times their original length,

and then completely saponifying them. The regenerated cellulose yarn thus produced may have' atenacity exceeding 4 grams per denier and an extensibility of 5-6%'.v Such high-tenacity yarns may be used in conjunction with continuous lilament yarns of cellulose acetate spun in the ordinary way, which will generally have an extensimore.

' it encounters the blade.

As the insulatingvarmsh with which the fabric l according to the present invention is to be treated to render it more suitable as' an insulating material, any appropriate composition may be employed that has no injurious effect on the stronger yarn contained in the fabric, and preferably none on either of the kinds of yarn. Insulating var' nishes of the type commonly employed and comprising a basis of a drying oil, such as linseed or China-wood oil, together with other ingredi` ents, e. g., driers, softeners and the like may be used. Other var-nishes, however, maybe used having a basis of a material capable on drying of forming a exible nlm, e. g. oil-modied resins such as oil-m'oded alkyd or phenol-formaldehyde resins. While it generally preferable that the varnish should be without injurious effect on the more extensible as well as Aon the poses, so to select the varnish and the Anature of the more extensible yarn that the latter is destroyed, orrendered veryA weak by the application of the varnish. By these means any tendency for even the mor extensible yarns to lo-h calise the stresses on the stronger yarns is avoided.

In this case the stronger yarns are held together in the finished product by the film that-isA formed by the varnishon' drying.

i stronger yarns, it'is possible, for particular purtherewith. Similarly all the unshaded weft yarns.

bath, past a doctor blade to remove excess varnish.

' The fabric then passes up a drying tower through which air heated to a temperature of C. is passed. The amount of varnish taken up by the fabric may be adjusted by adjusting the temperature (and therefore the viscosity) of the varnish, and by varying the height of the doctor blade above the surface of the bath so as to vary the degree of drying of the fabric before A fabric of the kind described above may, in this way, be given a finished thickness of from 4 mils. upwards. Thicker fabrics may, ofcourse, be produced by using yarns of greater weight.

vWhile the invention has been described above in connection with fabrics intended to be usedv present invention are shown in the accompanying drawing in which Figure 1 is a diagrammatic view of a plainwoven fabric and Figure 2 is a diagrammatic view of a 4- shaft ,fsatin fabric, both figures showing the manner in which the yarns of the fabrics are interlaced.

In Figure 1, which shows a plain-woven fabric,

the yarns of high tensile strength and relatively low extensibility are-shown at I and the yarns of low strength and high extensibility at 2, the yarns of the first kind being distinguished from those of the second kind by being lshaded while' those of the second kind are shown plain. It

will be seen that the -yarnsof the two kinds al-y ternate witheach other in both warp and weft, and as a result all theshaded weft yarns lie over all the shaded .warp yarns and arenot interlaced lieover all the unshaded warp yarns. Nevertheless, the cohesion of the fabric is brought about by the fact that the unshaded weft yarns, though passing over the unshaded warp yarns, pass under the shaded warp yarns while the unshaded warp yarns, though passing'under the unshaded u weft yarns. pass over the shaded weft yarns.

l. It will be seen that the shaded warp Yyarns j pass over all the shaded weft yarns and that the unshaded warp yarns pass over all the-unshaded weft yarns. The coherence of the yfabric is brought about, however, by the Yfact that the shaded warp yarns pass under one-half of the unshaded weft yarns while the unshaded warp yarns pass under one-half of the shaded weft yarns. Thisarrangement depends on the disposition ofthe shaded and unshaded pairs of weft kinds alternate two and two, as previously stated.

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

l. A fabric suitable for use as the basis of a varnished fabric, comprising in both warp and weft, yarns of high tensile strength and low extensibility and yarns of relatively low tensile strength and high extensibility, said yarns being so woven together that the yarns of low extensibility are not interlaced with one another to any substantial degree but depend substantially entirely for their maintenance in the fabric structure on the presence of the yarns of high extensibility.

2. A fabric suitable for use as the basis of a a varnished fabric, comprising in both warp and weft, yarns of high tensile strength `and. low extensibility and yarns of relatively low tensile strength and high extensibility, said yarns beingv so woven together that the yarns of low extensibility are not interlaced with one another to any substantial degree and the yarns of high extensibility are not interlaced with one another to any substantial degree, the yarns of each of the two kinds depending substantially entirely for their maintenance in the fabric structure on the presence of the yarns of the other kind.

3. A fabric suitable for use as the basis of a varnished fabric, comprising in both warp and weft, yarns of high tensile strength and low extensibility and yarns of relatively low tensile strength and high extensibility, said yarns being so woven together that the yarns of low ex In this fabric', the warp' the two kinds depending substantially entirely for their maintenance in the fabric structure on the presence of the yarns of the other kind, the

fabric having a 4-shaft satin weave wherein the yarnsalternate one and one in the warp and two and two inthe weft.

5. A fabric suitable for use as the basis of a varnished fabric, comprising in-both warp and weft, regenerated cellulose yarns of low extenssibility that have been subjected to a high degre'e of stretch in the course of their production weft, continuous lament yarns of low extensilto as to impart a high tenacityto them, and

yarns of relatively low tensile strength and high extensibility, said yarns'being so woven together that the yarns of low extensibility are not interlacedr with one -another to any substantial degree but depend substantially' entirely for their maintenance in the fabric structure on the presence of the yarns of high extensibility.

6. A fabric suitable for use as the basis of a varnished fabric,.comprising in both warp and weft, regenerated cellulose yarns of low extensibility that have been subjected to a high degreeof stretch in the course vof their production so as to impart a high tenacity to them, and yarns of relatively low tensile strength and high extensibility, said yarns being so woven together that the yarns of low extensibility are not interlaced with one another to any substantial degree, and the yarns of high extensibility are not interlaced with one another to any substantial degree, the yarns of each of the two kinds depending substantially entirely for the maintenance in the fabric structure on the presence of the yarns of the other kind, the'fabric having .a 4-shaft satin weave wherein the yarns alternate one and one in the warp and two and two l in the weft.

being sov woven .together that the yarns of low extensibility are not interlaced with one another to any substantial degree but depend substantially entirely for their 'maintenance in the fabric structure on the presence of the yarns of high extensibility. v

l8. vA fabric suitable for use as the basis of a varnished fabric, comprising in both warpand bility made by .saponifying cellulose ester filaments that have been stretched so as to impart a y high tenacity to them, and yarns of relatively l another to any substantial degree and the yarns weft, yarns of high tensile strength and low ex- Y tensibility and yarns of relatively low4 tensile strength and high extensibility, said yarns being so woven togethervthat the yarns of low extensibility are not interlaced with one another to any substantial degree and the yarns of high extensibility are not interlaced with one another to any substantial degree, the yarns of each of of high extensibility are not interlaced with one another to any substantial degree, the yarns of .each of the two lkinds vdepending substantially entirely for their maintenance in the fabric structure r`on the presence of the yarns vof the other kind; the fabric'having a 4shaft satin weave wherein the yarns alternate one and one inthe warpand .two and two in the weft.

-9. A fabric suitable for use at the basis of varbility, and thermoplastic yarns of relatively low tensile strength and high extensibility, said yarns beingso wovenv together that the yarns of low 7. A fabric suitable for us as the' basis of a yextensibility are not interlaced with one another to anysubstantial degree but depend substantiallyy entirely for their maintenance in the fabric structure on the presence of the yarns of high extensibility.

10. An insulating fabric comprising a basis of tial degree but depend substantially entirely for their maintenance in the fabric structure on the presence of the yarns of high extensibility, said woven fabric being impregnated with an insulating varnish that is inert to the materials of which the low extensibility yarns consist.

11. An insulating fabric comprising a basis of woven fabric, comprising in both warp and weft, yarns of high tensile strength and low extensibility and yarns of relatively low tensile strength and high extensibility, said yarns being so woven together that the yarns of low extensibility are not interlaced with one another to any substantial degree and the yarns of high extensibility are not interlaced with one another to anyv substantial degree, the yarns of each of the two kinds depending substantially entirely for their maintenance in the fabric structure on the presence of the yarns of the other kind, the fabric having a 4-shaft satin weave wherein the yarns alternate one and one in the warp and two and two in the weft, said fabric being impregnated with'an insulating varnish that is inert to the materials of which the low extensibility yarns consist.

-12. An insulating fabric comprising a basis of woven fabric, .comprisingin both warp and weft, regenerated cellulose yarns of low extensibility that have been subjected'to a high degree of stretch in the course of their'production so as to impart a high tenacity to them, and yarns of relatively low tensile strength and high'extensibility, said yarns being so woven together that the yarns of low extensibility are not interlaced with one another to any substantial degree and the yarns of high extensibility are not interlaced with oneanother to any substantial degree, the yarns of each ofthe twov kinds depending substantially entirely for their maintenance in the fabric structure on the presence of the yarns of Athe other kind, the fabric having ali-shaft satin weave wherein the yarns alternate one and one 55 the yarns of low extensibility are not interlacedin the warp. and "two-and two in the weft, said fabric being impregnated with an insulating var'- nish that is inert to the materials of which the low extensibility yarns consist.

13. A fabric suitable for use as the basis of a. varnished fabric, comprising in both warp and weft, continuous filament yarns of low. extensif bility made by saponifying cellulose ester filaments that have been subjectedto a high degree 'of stretch in the course of their production so as with one another to any substantial degree;the

yarns of each of the two kinds depending substantially entirely for their 4maintenance in the fabric structure on the presence 4of the yarns of the other kind, the fabric having a 4-shaft satin weave wherein the yarns alternate onaand one in the warp and two and two in the weft, said j 4 gamme fabric being impregnated with an insulating varnlsh that is inert to the materialsv of which the low extensibility yarns consist.

14. An insulating fabric comprising a basis of 5 woven fabric, comprising in both warp and weft,

regenerated cellulose yarns'of low extensibility that have beensubjected to a high degree of stretch in the course of their production so as to impart a high tenacityto them, andyarns of relatively low tensile strength andhigh extensibility, said yarns being so woven together that 'the yarns of low extensibility are not interlaced with one another to any substantial degree and the yarns of high extensibility are not interlaced with one'another to any substantial degree-the yarns of each of the two kinds depending substantially entirely for their maintenance in the fabric structure on the presence of the yarns of the other kind, the fabric having a 4-shaft satin 420 weave wherein the yarns alternate one and one adrying oil.-` 15. A fabric suitable foruse as the basis of a varnished fabric, comprising in both warp and weft, continuous filament yarns of low extensibility made by saponifying cellulose ester filaments that have been subjected to a high degree of stretch in the course of their production so as to impart a high tenacity to them, and yarns of relatively low tensile strength and high extensibility, said yarns being so woven together that the yarns of low extensibility are not interlaced with kind, the fabric having a i-shaft satin weave wherein the yarns alternate one and one in'the warp and two and two in the weft, said fabric being impregnated with an insulating varnish that is inert to the materials of which the low extensibility yarns consist,and has a basis of a drying oil. i

16. An insulating fabric comprisinga basis of woven fabric, comprising in both warp and weft,

vregenerated cellulose yarns of low extensibility that have been subjected 'to a high degree of stretch in the course of their production so as to impart' a high tenacity to them, and yarns of relatively low tensile strength and high extensibility, said yarns being so woven together that Withone another to any substantial degree and the yarns of high extensibility are not interlaced with one another to any substantial degree, the yarns of each of the two kinds depending substantially entirely for their maintenance in the Kfabric structure on the presence of the yarns of the other kind, the fabric having a 4-shaft satin weave wherein the yarns alternate one and one in the warp and two and twoV in the weft, said fabric being impregnated with an insualting varnish that is inertto the materials of which thelow extensibility yarns consist, and has a basis of an oil-modied alkyd resin.

17` A'fabric suitable for use as the basis of a varnished fabric, comprising in both warp or weft, continuous lament yarns of low extensi^ bility, made by saponifying cellulose ester fila,- -ments that have been lsubjected to a high degree of stretch in the course of 'their production so as 'Il to impart a high tenacity to them, and yarns of relatively low tensile strength and high extensibility, said yarns being so woven togetherthat the yarns of low extensibility are not interlaced with one another to any substantial degree, the yarns of each of the two kinds depending substantially entirely for their maintenance in the fabric structure on the presence of they yarns of theother kind, the fabric having a 4-shaft satin weave wherein the yarns alternate one and one in the warp and two and two in the weft, said fabric being impregnated with an insulating var-- nish that is inert to the materials of which thu low extensibility yarns consist, and has a basic of an oil-modified alkyd resin.

DONALD FINLAYSON. HARRY CRAWSHAW.

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