US2021717A - Textile yarn and fabric - Google Patents

Description

. duced with the aid of highly twisted cellulose Patented Nov. 19, 1935 PATENT, OFFICE TEXTILE YARN AND FABRIC Henry Dreyfus, London, and William Alexander Dickie andjiobert Wighton Moncrieff, Spondon, near Derby, England, assilnors to Celanese Corporation of America, a corporation of Delaware No Drawing. Application May 11, 1932, Serial No. 610,702. In Great Britain May 15, 1931 12 Claims.

This invention relates to the manufacture of textile fabrics and textile yarns suitable for incorporating therein, and is more particularly concerned with the production of fabrics exhibiting crepe effects.

Textile materials exhibiting crepe effects have longbeen obtained by employing in their construction highly twisted yarns of natural silk in the gummed state. Upon scouring such a fabric in an aqueous bath the well-known crepe effects appear and the fabrics so obtained have long been highly prized on account of their great beauty and-pleasing handle. The production of crepe fabrics by utilizing highly twisted yarns consisting of or containing filaments of artificial silk has, however, been accompanied by considerable difllculties, more particularly in the case of utilizing highly twisted yarns made of filaments of cellulose acetate.

In British Patent No. 348,589, there is, however, described a process whereby there may be proacetate yarns, fabrics exhibiting crepe effects comparable in character with those obtainable on According to that specification, the highly twistedcrpe threads are impregnated with a suitable material and after incorporation into fabrics, the fabrics are subjected to a treatment adapted to swell the impregnating materials, which preferably have been so applied as to surround effectively the filaments of the crepe threads. The swelling treatment is essentially such "as will not render the impregnating material excessively soft or yielding. It appears that the swelling of the impregnating material within the highly twisted crepe threads forces apart the filaments thereof and so causes, on account of the high twist, a, diminution in the length of the crepe threads. In this specification it will be noted, the means specified for effecting the swelling of the impregnating material and hence the shrinkage of the crpe threads, are

' physical in character.

soluble sulphate, for example potash alum, and thereafter treated with a solution of lead acetate in order to form lead sulphate within the highly twisted crepe threads and scoured. The shrinkage consequent upon the formation of the lead 5 sulphate may be due to the forcing apart of the filaments and the contraction brought about by the high twist, or may be due to a strain set up by the increase in volume, or again may be due to a strain set up by the surface contraction brought about by the formation of the solid material. Whatever the mechanism of the process, however, the yarns are constrained to shrink in length to a very considerable degree and to give rise to, crepe effects of an excellence hitherto unattained or attained only with great difiiculty in the case of fabrics containing highly twisted crepe threads of cellulose acetate filaments. We have further found that the formation of other solid or semi-solid materials within the crepe threads may be utilized in an analogous manner for the production of crepe effects.

The formation of the solid or semi-solid materials may be effected in the woven fabrics as outlined above or may be effected at other stages of the manufacture of the fabrics. The compounds may for instance be produced within the crepe threads prior to weaving and in fact at any convenient stage in their production, for example prior to the application of the high degree of twist requisite therein.

It has been found, however, that most satisfactory results are obtained when the solid or semi-solid compound is formed within the crepe threads in the finished fabrics. Moreover, it has been found that it is particularly advantageous to incorporate a suitable reagent in the crepe threads prior to weaving and especially prior to the application of a substantial proportion of the twist and then to convert the said reagent into a suitable solid or semi-solid compound after the threads have been incorporated into fabrics. Thus in the case wherein lead sulphate is produced. within the crepe threads, cellulose acetate yarn of low twist, for example 5 turns per inch, may be impregnated with the potash alum in. the form of an aqueous solution and the impregnated yarn thereafter twisted in one or more stages to the requisite high degree, for example 50 to 60 turns per inch. The impregnated and 50 twisted yarn may then be woven into a warp and the resulting fabric subjected to the action of an aqueous solution of lead acetate or other soluble lead salt, and thereafter scoured. By operating in this manner the formation of the lead sulphate 66 or other solid or semi-solid material is effected well within the crepe threads and around the individual filaments constituting the latter. Shrinkage of the crepe threads to the maximum possible degree is thereby assured.

The application of a reagent subsequently to be converted into a solid or semi-solid material may be effected in various ways. Thus, for example the yarn to be utilized as crepe threads may be impregnated, either before or after crepe twisting, with a solution of the requisite reagent, while in the form of hanks or while wound on perforated bobbins or other form of yarn container, and the impregnation may be assisted by the employment of vacuum in the well-known manner. Most conveniently, however, the solution of the reagent may be applied to the yarn while winding from one package to another. The impregnated yarn may then be dried.

The application to the crepe threads of, part or the whole of the requisite high degree of twist may be effected simultaneously with such-an impregnating operation, the yarn being dried, if desired, by means of warm air or otherwise prior to the rewinding. Particularly good results are obtained, however, if at least a part of the crepe twist is applied in an operation following the application of the reagent. Further, it is preferred to apply the high degree of twist in two or more stages rather than in a single operation. Thus, yarn of low twist may be passed through a solution of the reagent, dried if desired, and then twisted to 15 to 30 turns per pinch and thereafter to the high degree necessary in the final threads, for example 45 to 70 turns per inch or more, e. g. turns per inch, in a second operation. Alternatively, the reagent may be applied between the two twisting operations and, if desired, simultaneously with one of them. In practice very good results may -be obtained by twisting yarn of about 5 turns per inch up to about 25 turns per inch on a machine of the type in which twist is applied as the'yam is drawn off its package, the drawn off and twisted yarn being passed through the aqueous or other solution of the reagent on the way to the rewinding device. The yarn so produced is thereafter twisted to 50 to 60 turns per inch or more in a separate operation. I

Solid or semi-solid materials of widely varying character may be produced by chemical means within the crepe threads and around the filaments thereof in-the production of fabrics exhibiting crepe effects in accordance with the present invention. As, however, it"is usually most convenient to utilize aqueousreagents in the production of said materials, materials which are not soluble or are only diflicultly soluble in water are to .bepreferred. As examples of such com-- als, where these are sufficiently difficultly soluble in water.

The difficultly soluble salts may comprise eithe organic or inorganic acid radicles. For example,

there may beutllized the sulphates, carbonates or phosphates of the alkaline earth metals or of lead, or the carbonates or phosphates of other of the foregoing metals. In practice, however,

the diflicultly solubleiorganic acid salts of the foregoing metals have been found especially convenient. As examples of such organic acids, mention may be made of dior poly-basic carboxylic acids or dior poly-basic hydroxy carboxylic acids, for example, oxalic acid, tartaric. acid, citric acid, mucic acid or saccharic acid. 5 Again, there may be mentioned the higher fatty acids, for example oleic, stearic, palmitic, ricinoleic or lauric acid. All of these acids are capable of yielding difficultly soluble salts with one or other of the foregoing metals. Other difficultly l0 soluble compounds may be utilized, however, for example metal compounds of casein or other albuminous materials.

The reactions involved in the production of the insoluble or diflicultly soluble materials may 15 be of any desired character, for example difiicultly soluble metal salts may be produced by interaction between a water-soluble salt of the metal and a water-soluble alkali metal salt of the appropriate acid, e. g. sodium citrate, sodium 0 tartrate, or Rochelle salt. Again, an appropriate acid may be caused to react with a water-soluble hydroxide of a metal, for example calcium or barium hydroxide.

As one of the reagents is in general preferably 25 applied to the crepe threads during their manu facture and prior to the application of at least part of the twist, the reagent so applied will in general, though not necessarily, be in substantially solid form in the material at the time of applying a further reagent or reagents and the reaction requisite for the production of the solid or semi-solid salt or other compound will therefore generally be between a solid reagent and another reagent, the latter usually in the form of an aqueous or other solution. If desired, however, a second or subsequent reagent may be applied in the form of a gas; for example, ammonia may be caused to react with an aluminium salt so as to produce aluminium hydroxide within the crepe threads.

The compounds formed within the materials and the reagents used to effect the said formation may with advantage be such that the bulk of the material formed is relatively large in comparison 40 with the bulk of the reagent first applied to or incorporated within the crepe threads.

of an insoluble or difllculty soluble metal salt, which when prepared with the aid of an aqueous solution, prior to or during the application of the high crepe twist and are then treated with barium hydroxideuafter, weaving into fabrics, a large increasein the bulk ofthe yarn takes place and a corresponding shrinkage in length on account of the high twist. Other' compounds may likewise be produced in hydrated, solid or semisolid form, for-example other metal salts or aluminium or other metal hydroxide.

As previously indicated it is usually most convenient from the point of view of ease of application to produce within the crepe threads materials which are insoluble or diiilcultly soluble in water. The invention is not however restricted to the use of such materials, as materials having appreciable solubility in water may be utilized,

- providing they are produced with reagents in an appropriate form. For example, if aqueous reagents are used there,may be added thereto alkali metal salts, for example sodium chloride or potassium chloride or other substances capable of diminishing the solubility in water of the material it is desired to produce within the crepe threads. In the case, for instance, of producing barium citrate or other difiicultly soluble salt from an acid and a base, material impregnated with an appropriate acid may be treated with a solution of the base, for example barium hydroxide, containing ethyl alcohol or containing sodium chloride in substantial proportion, e. g. up to saturation, in order to assist the separation of the barium citrate or other material within the crepe threads and prevent its solution by the aqueous reagent employed. Such additions of alcohol, salts, and the like to reagents may also serve to prevent solution and removal from the crpe threads of citric acid or other reagenttherein prior to its conversion into the desired solid compound. This method of assisting the formation of the desired compounds within the materials constitutes an important and valuable feature of the present invention, more particularly so in view of the fact that many of the compounds, for example, a hydrated barium citrate or other hydrated salts'of organic acids which may be produced iii-relatively large bulk from relatively small quantities of reagent in the crepe threads, are appreciably soluble in water itself but are less soluble-in aqueous alcohol or concentrated solutions of sodium chloride or other salts.

In general the reactions utilized for the production of the solid or semi-solid materials within the crepe threads may be advantageously effected under such conditions as to separate the material in maximum quantity and in the most advantageous physical form from the point of view of securing good shrinkage of the crepe threads. It is often beneficial for example to effect the reactions at elevated temperatures or to leave the materials in contact with the reagents for prolonged periods, for example 12 to 24 hours, or to incorporate wetting agents in the reagents. When forming calcium citrate from citric acid or sodium citrate andcalciunr chloride the fabric containing highly twisted yarns prepared with citric acid. or sodium citrate maybe left in contact with calcium chloride solution, preferably highly concentrated for several hours with or without heating. Again, when producing barium citrate, for instance,.in the above described manner, the barium hydroxide solution, whether containing or not alcohol or salts or. other additions, may with advantage be applied at 60-80 C. or even at temperatures up to the boiling point.

It has further been found that-instead of or in addition to applying heat during the formation of the insoluble or diflicultly soluble compounds, the materials may with great advantage subsequently be'subjected to a hot aqueous treatment, for example in an aqueous scouring bath, e. g. a both containing a soap or sulphonated soap, for instance Turkey red oil, or a wetting agent. In the case of materials containing cellulose acetate crepe threads the hot aqueous treatment is preferably carried out at temperatures above C., e. g. at 80-85 C. or even at temperatures up to scribed in British Patent No. 352,451,

' alkaline earth hydroxide.

c. Hot aqueous baths may contain neutral salts or other substances adaptedto minimize reduction of lustre.

The proportions of reagent incorporated in the crepe threads may vary within wide limits and according to the nature of the reactions to be utilized and the effects it is desired to produce. The proportion incorporated may be regulated for instance by varying either the quantity or concentration or both quantity and concentration of the solution in which the said reagent is applied. In the case of producing barium citrate for instance, citric acid may be incorporated in the proportion of 1 to 5 per cent. or more of the weight of the threads; applied in the form of aqueous solutions of 10, 20 or 30 per cent. concentration or even of concentrations up to that of saturated solutions.

After the dimcultly soluble metal salts or other solid materials produced within the crepe threads have served their purpose in the production of the desired crepe effects, they may be removed from the fabrics if desired or requisite. In general, it will be found convenient to select compounds which admit of ready removal from textile materials. Such removal may be effected in many cases by simple mechanical means, for example by thorough washing and agitation with water or other liquids, or by chemical means ascording to the precise nature of the material in question. Where-a hot aqueous scour or like treatment is applied in the manner previously indicated, such treatment may simultaneously serve to effect the removal of the diflicultly soluble compounds.

The crepe threads employed in accordance with the present invention may, if desired, be sized at any suitable stage of their manufacture. In this connection particular mention may be made of sizing materials which may be caused to swell without becoming soft or yielding by suitable treatment, particularly by the subsequent treatment of the fabrics in ordertoproduce,

by chemical means, suitable compounds therein or by a scouring treatment where such is employed. The sizing materials may be selected with advantage according to the principles laid down in British Patent No. 348,589. Again, the

crepe threads or the filaments contained therein may be sized with or provided with a coating of a cellulose or a cellulose derivative as described in British Patent No. 357,169, or with a coating of a polymerized vinyl compound or other polymerized or condensed organic compound as .de-

'Any sizes or coatings m'ay be applied intermittently to the threads as describedin U. S. Patent No. 1,966,440 and British Patent No. 365,041.

Sizing materials, where. employed, are prefer ably applied to or formed on the crepe threads prior to the application of a substantial degree of twist and convenently may be applied simultaneously with a reagent adapted subsequently to be converted by chemical means into a mate-- rial of greater bulk in accordance with the foregoing processes. A casein size saturated with citric acid or other suitable organic acid may, for example, be employed, and the fabrics subsequently treated with'a solution of barium or other In this. manner there may be simultaneously effected a swelling of the casein size and a formation of barium or other alkaline earth citrate or other compound, whereby a substantial shrinkage of the crpe threads may be caused to take place.

Again, the treatment applied to produce by chemical means within the crepe threads a suitable solid or semi-solid material, may be one which is also adapted to cause a swelling of the material of the crepe thread filaments without causing it to become excessively soft or yielding or may be applied in conjunction with such a swelling treatment. For examples of such swelling treatments reference may be made to U. S. Patent No. 1,995,296 and British Patents Nos. 352,000 and 357,084. For instance, where an acid is employed for the production of .the requisite material by chemical means within the crepe threads, the acid may be one capable of swelling cellulose acetate material in the presence of water or may be applied in admixture with such a substance, e. g. alcohol. The acid may, for instance, be applied to the crepe threads prior to twisting in the form of an alcoholic solution. Crepe threads may thus be produced which, upon treatment with an aqueous solution containing a suitable base, for example barium hydroxide, have formed therein an insoluble barium salt of the acid utilized, while at the same time a swelling of the material of the filaments takes place. Again, cellulose acetate yarn may, either before or after crepe twisting, be dehydrated by means of a concentrated calcium chloride solution, as described in British Patent No. 357,084, woven into fabrics and the latter treated with a reagent capable of forming an insoluble calcium salt with calicum chloride. Such a reagent may, for instance, be a soluble sulphate, carbonate or suitable salt of an organic acid. Alternatively, one of the latter reagents may be incorporated in the crepe threads, the latter woven into fabrics and the said fabrics subjected to the action of a concentrated solution of calcium chloride and finally washed or scoured. In these ways also' simultaneous swell'ng and production of solid material, e. g. calcium sulphate or carbonate, within the crepe threads may be efiected. If desired, however, a swelling treatment may be applied in an operation independent of the process of producing the solid or semi-solid material within the crepe threads.

As stated previously, the invention is of particular value in connection with the production of crepe fabrics with the aid of highly twisted yarns consisting of cellulose acetate filaments. Crepe threads comprising filaments of other organic derivatives of cellulose may be employed in an analogous manner. As examples of such cellulose derivatives may be mentioned cellulose formate, propionate or butyrate or other cellulose esters of organic acids, or methyl, ethyl or benzyl cellulose or other cellulose ethers. If desired, crepe threads consisting of. or comprising filaments of other materials may be employed, for example filaments of silk, cotton, or of artificial silk of the regenerated cellulose type. The crepe threads may also be composed of filaments of two or more different kinds whether in respect of material or denier or both. Thus there may be used threads containing both filaments or cellulose esters or ethers and filaments of natural silk or regenerated cellulose artificial silk, or threads containing cellulose ester or ether filaments of two or more difierent deniers. Further, the crepe yarns may consist, wholly or in part, of staple fibre" i. e. relatively short lengths of filament.

The degree of twist imparted to the crepe threads made or used according to the present invention, may be similar to that commonly employed in the case of crepe threads of natural silk in the gum. For example, as previously indicated, a twist of from 45-70 turns per inch may be employed. In general a twist of about 60-65 turns per inch has been found to give highly satisfactory results, but higher twists, for example 5 75-85 or more turns per inch, may be employed with advantage in some. cases, particularly when the filaments are of very low denier (see British Patent No. 357,577). Any other suitable degree of twist may, however, be employed according to the nature and denier of the filaments constituting the crepe threads and according to the effects it is desired to produce. Moreover, the twist may be irregular in character, varying frompoint to point along the crepe thread, as described in British Patent No. 358,585. Further, the requisite high degree of twist may be applied in two or more stages with or without intermediate sizing, in the manner described in British Patents Nos. 332,903 and 375,355.

The highly twisted crepe threads may be incorporated in the fabrics in any suitable manner, for example the weft alone may be wholly or partially composed of such threads or the warp may also contain them. In the former case the finished fabrics exhibit chiefly shrinkage in the direction of the weft. It is found particularly convenient however, in generaLto employ threads of relatively low twist in the warp and to employ in the weft both crepe threads having a left-hand twist and crepe threads having a right-hand twist. Such threads may be disposed in the fabrics in any convenient manner, for example pairs of threads of left-hand twist may alternate with pairs of threads of right-hand twist. A further method of constructing the fabrics is to weave composite crepe threads consisting of a yarn of high twist doubled with a yarn of low twist, or consisting of two yarns of high but opposite direction of twist, the yarns being prepared and the fabrics subsequently treated in accordance with the processes of the invention. In this manner crepe fabrics may be readily produced without the necessity for the employment of a loom capable of weaving two different types of yarn such as is necessary when alternate picks of yarn of left-handed twist and yarn of right-handed twist are to be woven. In this'connection reference is made to U. S. applications S. Nos. 444,619, filed 15th April, 1930 and 589,304, filed 27th 1 January, 1932.

Where the fabrics comprise yarns of low twist, the latter may be either of the same material or of a different material from that of the highly twisted crepe threads. For example, where the crepe threads are composed of cellulose acetate filaments, the said yarns of low twist may be composed of cotton or of a regenerated cellulose type of artificial silk.

In the case of fabrics containing low twist yarns as well as the highly twisted crepe threads, such yarns, particularly when forming the warp of the material, will usually be sized. In this event it has been found beneficial to employ sizes which are easily removed or at least easily soft- 5 ened by the treatments subsequently to be applied to the fabrics in accordance with the invention. Indeed, if desired, the said treatments may be modified, for example in respect of temperature or other conditions, or a special treatment may be applied, for thepurpose of softening or removing the size on the yarn of low twist.

Preferably the size on the said low twist yarns should be more easily softened or removed than any size which may have been applied to the highly twisted crepe threads in the fabrics. Again, when utilizing yarns of low twist in con junction with the crepe threads of high twist, the said low twist yarns may be of such character or be so treated as to be less readily wetted than the crepe threads. For instance they may be oiled with an animal, vegetable, or mineral oil prior to incorporation into the fabrics.

The invention is illustrated but not limited by the following examples:-

Example 1 Cellulose acetate yarn of 100 denier 26 filaments, twisted to one turn per inch, is twisted to 26 turns per inch and then passed over a roller revolving in a bath of citric acid solution of 10 per cent. strength. The yarn is subsequently twisted up to 67 turns per inch. Yarn of lefthand twist as well as yarn of right-hand twist is prepared. The twisted and treated yarn is then woven into a warp consisting of cellulose acetate threads of denier, twisted one turn per inch, two picks of left-hand twisted yarn alternating with two picks of righthand twisted yarn in the weft, the total number of picks being per inch.

The resulting fabric is then immersed for several hours in a two per cent. aqueous solution of barium acetate, preferably containing a small proportion of alcohol. The fabric is thereafter washed, dyed and finished.

Example 2 Cellulose acetate yarn of 75 denier is twisted to 26 turns per inch, passed through a concentrated solution of lead acetate and thereafter twisted up to '70 turns per inch. The resulting treated and twisted yarn is thereafter woven into a warp containing 80 ends per inch of cellulose acetateyarn of 75 denier and 22 turns per inch twist. 80 picks per inch of weft are employed with a 5 shaft satin weave. The woven fabric is then immersed for some time in a 10 per cent. aqueous solution of potash alum, and is subsequently scoured and finished.

Example 3 Cellulose acetate yarn of denier is twisted to 26 turns per inch and treated with a 30 per cent. solution of sodium citrate. The yarn is then further twisted up to 67 turns per inch righthand. A further quan 'ty of yarn is prepared in the same manner but with left-hand twist. The prepared yarn is thereafter woven into a cellulose acetate warp of low twist, two picks of left-hand twist yarn alternating with two picks of righthand twist yarn. The fabric is then immersed for several hours in a solution containing 4 per cent. of barium hydroxide and saturated with common salt. The resulting fabric is finally scoured and finished. 1

Example 4 Cellulose acetate staple fibre yarn of 12s cotton counts with 20 turns per inch twist is passed through a 30 per cent. solution of citric acid. It is then twisted up to 62 turns per inch right-hand,

a similar quantity of yarn being prepared in the.

Patent 18:-

.agent adapted to react with the first reagent to 1. Process for the production of a fabric exhibiting crepe effects which comprises'incorporating in a fabric -a highly twisted thread produced by applying part of the high twist 'to a thread, impregnating the partly twisted thread 5 with a suitable reagent and then completing the high twist, and thereafter subjecting the fabric to theaction of a reagent adapted to react with the first reagent to form a solid material in the highly twisted threads. 10

2. Process for the production of a fabric exhibiting crepe effects which comprises incorporating in a fabric a highly twisted thread produced by applying part of the high twist to a thread of filaments of an organic derivative of 15 cellulose, impregnating the partly twisted thread with a suitable reagent andthen completing the high twist, and thereafter subjecting the fabric to the action of' a reagent adapted to react with the first reagent to form a solid material in the 20 highly twisted threads.

3. Process for the production of a fabric exhibiting crepe effects which comprises incorporating in a fabric a highly twisted thread produced by applying part of the high twist to a 25 thread of cellulose acetate, impregnating the partly twisted thread with a suitable reagent and then completing the high twist, and thereafter subjecting the fabric to the action of a reagent adapted to react with the first reagent to form a 30 solid material in the highly twisted threads.

4. Process for the production of a fabric exduced by twisting cellulose acetate thread to at 35 least 15 turns per inch, impregnating the partly twisted thread with a suitable aqueous reagent and then completing the high twist, and thereafter subjecting the fabric to the action of a reform a solid material in the highly twisted threads.

5. Process according to claim 4 wherein the total twist is 60-85 turns per inch.

6. Process for the production of a fabric exhibiting crepe effects which comprises incorporating 45 in a fabric a highly twisted thread produced by twisting cellulose acetate thread to at least 15 turns per inch, impregnating the partly twisted thread with an aqueous solution of a salt and then completing the high twist, and thereafter 5o subjecting the fabric to the action of a reagent adapted to react with the salt to form a solid material in the highly twisted threads.

7. Process for the production of a fabric exhibiting crepe effects which comprises incorpo- 5 rating in a fabric a highly twisted thread produced by twisting cellulose acetate thread to at least 15 turns per inch, impregnating the partly twisted thread with an aqueous solution of an alkali metal salt and then completing the high twist, and thereafter subjecting the fabric to the action of a reagent adapted to react with the salt to form a solid insoluble salt in the highly twisted threads. 65

8. Process for the production of a fabric exhibiting crepe effects which comprises incorporating in' a fabric a highly twisted thread produced by twisting cellulose acetate thread to at least 15 turns per inch, impregnating the partly 7 twisted thread with an aqueous solution of an alkali metal salt of an acid containing at least two carbonyl groups and then completing the high twist, and thereafter subjecting the fabric to the action of areagent adapted to react with It boxylic acid in the highly twisted threads.

9. Process for the production of a fabric exhibiting crepe efiects which comprises incorporating ina fabric a highly twisted thread produced by twisting cellulose acetate thread to at least 15 turns per inch, impregnating the partly twisted thread with an aqueous solution of an alkali metal salt of citric acid and then completing the high twist, and thereafter subjecting the fabric to the action of an aqueous solution of an alkaline earth salt.

10. Process for the production of a fabric exhibiting crpe effects which comprises incorporating in a fabric a highly twisted thread produced by twisting cellulose acetate thread to at least 15 turns per inch, impregnating the partly twisted thread with aqueous citric acid and then completing'the high twist, and thereafter subjecting the fabric tothe action of an aqueous solution of an alkaline earth hydroxide.

11. Process for the production of a fabric exhibiting crepe effects which comprises incorporatthe salt to form a solid insoluble salt of the caring in a. fabric a highly twisted thread produced by twisting cellulose acetate thread to atleast 15 turns per inch, impregnating the partly twisted thread with aqueous citric, acid and then completing the high twist, and thereafter subjecting 5 12. Process for the production of a fabric exhibiting crepe effects which comprises incorporating in a fabric a highlytwisted thread produced 10 by twisting cellulose acetate thread to at least 15 turns per inch, impregnating the partly twisted thread with a suitable aqueous reagent and then completing the high twist, and thereafter subjecting the fabric to the action of an aqueous solu- 15 tion of a reagent adapted to react with the first reagent to form a solid material in the highly twisted threads, said aqueous reagent containing a substance minimizing solution of the first reagent from the material. g0

HENRY DREYFUS.

WILLIAM ALEXANDER DICKIE. ROBERT WIGHTON MONCRIEFF.

CERTIFICATE OF CORRECTION.

Patent No. 2,021,717. November 19, 1935.

HENRY DREYFUS, ET AL.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows; Page 2, first column, line 33, for

"pinch" read inch; page 4, second column, line 19, for "Patents Nos." read Patent No.; line 20, for "332,903 and 375, 355" read 357,576; line 49, beginning with"U. S." strike out ali to and including "i932" in line 51, and insert instead British Patents N0s.332,903

and 375,355; and that the said Letters Patent should be read with thcse-c0rrections therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 14th day of January, A. D. 1936.

Leslie Frazer (Seal) Acting Commissioner of Patents.