US3734799A

US3734799A - Process for sulfolane bonding of textile fibers

Info

Publication number: US3734799A
Application number: US00053021A
Authority: US
Inventors: R Schaffer; J Moseley; D Sharrod
Original assignee: Shell Oil Co
Current assignee: Shell USA Inc
Priority date: 1969-07-09
Filing date: 1970-07-07
Publication date: 1973-05-22
Anticipated expiration: 1990-05-22
Also published as: GB1252191A; NL166289B; FR2051620B1; CA941696A; ZA704670B; DE2033664B2; DE2033664A1; ES381538A1; FR2051620A1; NL166289C; NL7009991A; BE752694A; DE2033664C3

Abstract

FIBERS OF TEXTILE ARTICLES ARE BONDERED BY APPLYING A BLEND OF A SULFONLANE AND AT LEAST ONE ORGANIC DILUENT, HAVING AN EVAPORATION RATE OF BETWEEN 0.01 AND 0.50 TIMES THE EVAPORATION RATE OF THE SULFONLANE AT 100*C. AND MISCIBLE THEREWITH, TO THE FIBERS AND HEATING THE ARTICLES SO AS TO BOND THE FIBERS.

Description

US. Cl. 156-308 12 Claims ABSTRACT OF THE DISCLOSURE Fibers of textile articles are bonded by applying a blend of a sulfolane and at least one organic diluent, having an evaporation rate of between 0.01 and 3.50 times the evaporation rate of the sulfolane at 100 C. and miscible therewith, to the fibers and heating the article so as to bond the fibers.

BACKGROUND OF THE INVENTION The use of sulfolane alone as a latent solvent for certain polyacrylonitrile fibers has been suggested in British Pat. No. 993,498. It has been found that sulfolane fails to effect appropriate bonding of modacrylic and cellulose ester fibers when applied as such to the fibers in accordance with a process analogous to that described in British Pat. No. 993,498. However, it has now been found that such fibers may nevertheless be bonded quite satisfactorily when sulfolane is applied under special conditions, i.e., when blended with certain organic diluents. The use of blends of .snlfolane and the latter diluents also has advantages when applied to effect bonding of polyacrylonitrile fibers or chlorofibers. For example, if a batt of the latter fibers is through-bonded with a blend of sulfolane and an organic diluent in accordance with the present invention, a softer, loftier wadding is obtained than by through-bonding a batt of these fibers with sulfolane alone. Moreover, if a woven textile article comprising polyacrylonitrile fibers or chlorofibers is surface-bonded with a blend of sulfolane and an organic diluent in accordance with the present invention, the resulting surface-bonded textile article has betterhandling characteristics than a textile article surface-bonded with sulfolane alone.

SUMMARY OF THE INVENTION The invention is directed to a process for bonding fibers of textile articles andwith the bonded fiber textile articles resulting therefrom.

The invention is particularly concerned with bonding the fibers of textile articles wherein said fibers are polyacrylonitrile, modacrylic, cellulose ester fibers or chloro fibers or a mixture thereof. The unqualified term fibers as used hereinafter represents at least one of the aforesaid fibers.

The fibers of the textile article are bonded by applying a blend of sulfolane and at least one organic diluent to the fibers and heating the article so as to bond the fibers. This blend acts as a latent solvent for the fibers; that is, as a liquid which is a non-solvent for the fibers at room temperature but which is activated by heat to become a solvent for the fibers.

The textile articles whose fibers can be bonded in accordance with the present invention may be woven, nonwoven, knitted or tufted textile articles of staple fibers or continuous multior monofilaments. The textile articles may be through-bonded or surface-bonded. Generally textile articles are through-bonded to improve their strength or surface-bonded to improve their aesthetic ap United States Patent O pearance and to increase theirresistance to pilling. A I

Patented May 22, 1973 through-bonded textile article is produced by bonding some or all of the fibers throughout the thickness of the textile article whereas a surface-bonded textile article is produced by bonding some or all of the surface fibers only of the textile article.

DESCRIPTION OF THE PREFERRED EMBODIMENT The present invention is specifically concerned with a process for bonding the fibers of a textile article which comprises applying a blend of a sulfolane (as hereinafter defined) and at least one organic diluent to the fibers of said textile article and heating said textile article so as to bond said fibers, the organic diluent being inert to the fibers of the textile article, miscible with said sulfolane, and having an evaporation rate of between 0.01 and 3.50 times the evaporation rate of said sulfolane at 100 C. and the fibers being polyacrylonitrile, modacrylic, cellulose ester fibers or chlorofibers.

The term polyacrylonitrile denotes fibers comprising both homopolymers of acrylonitrile and copolymers containing at least by weight of polymerized acrylonitrile units. Suitable comonomers may be organic compounds containing at least one ethylenically unsaturated carbon to carbon bond, such as vinyl acetate, vinylidene chloride, vinyl chloride, methyl acrylate, methylmethacrylate, vinyl pyridine or styrene. Fibers comprising copolymers of such unsaturated organic compounds and acrylonitrile containing from 35 to 85 by weight of polymerized acrylonitrile units are referred to in this disclosure as modacrylic fibers.

Examples of polyacrylonitrile fibers which may be used in the process of this invention include the fibers known under the following trademarks or trade designations: Orlon-42, Courtelle, Dralon and Acribel. Examples of modacrylic fibers are those known under the following trademarks or trade designations: Dynel, Verel, Kanekalon and Teklan.

Dynel is a fiber comprising a copolymer of vinyl chloride (60%) and acrylonitrile (40%), Verel is a fiber comprising a copolymer of vinylidene chloride (40%) and acrylonitrile (60%), Teklan is a fiber comprising a copolymer of vinylidene chloride (50%) and acrylonitrile (50%) and Kanekalon is a fiber comprising a copolytrier of vinyl chloride and acrylonitrile. (The percentages given in parentheses are approximate values only.)

Cellulose ester fibers are cellulose derivatives comprising aliphatic carboxylic acid moieties, such as cellulose diacetate, cellulose acetobutyrate. Examples of suitable cellulose ester fibers are commercially available under the registered trademarks Dicel and Tricel.

The chlorofibers are fibers comprising homopolymers or copolymers of vinyl chloride or vinylidene chloride. Suitable comonomers are those listed above as comonomers for polyacrylonitrile or modified polyacrylonitrile copolymers, it being understood that acrylonitrile is excluded as a suitable comonomer to produce chlorofibers. An example of a commercially available chlorofiber is Fibravyl (trademark). Fibravyl is a fiber comprising principally polymerized vinyl chloride.

The fibers of the textile articles may comprise a blend of one or more of the above-mentioned fibers with one or more different synthetic fibers or natural fibers. For example, the fibers of a blend of polyacrylonitrile fibers and wool or polypropylene fibers may be bonded according to the present process. 'Generally, the textile article should comprise at least 25% by weight of fibers of the textile article, of polyacrylonitrile, modacrylic, cellulose ester fibers or chlorofibers or a mixture thereof.

The term sulfolane includes sulfolane itself and substituted sulfolanes with up to 8, preferably not more than 4 carbon atoms. Examples of substituted sulfolanes are 2-methyl sulfolane, 3-bntyl sulfolane, 3-isopropyl sulfolane, 3-n-hexyl sulfolane, 2-methyl-4-butyl sulfolane and 3-cyclohexyl sulfolane. Blends comprising unsubstituted sulfolane (tetramethylene sulfone) are preferred.

Clearly if the blend applied to the fibers of the textile articles according to the invention comprises tetramethylene sulfone as latent solvent then the organic diluent should have an evaporation rate of between 0.01 and 3.5 times the evaporation rate of tetramethylene sulfone at 100 C. Stated in general terms, the organic diluent present in the blend should have an evaporation rate of between and 3.5 times the evaporation rate at 100 C. of the particular sulfolane present in the same blend.

As stated hereinbefore the organic diluents used in the process of this invention are diluents which are inert to the fibers and are miscible with sulfolane. By inertness is meant herein that the diluent should not be a normal solvent for the fiber, nor should it be capable of modifying the desirable physical characteristics of the fiber to a major extent. It may display some latent solvency charac teristics provided these are less than those of sulfolane. Likewise the inert diluents may be capable of acting as plasticizers for the fibers, provided this plasticizing effect of the diluents on the fibers is not too strong i.e., does not unduly modify the desirable properties of the fibers and the bonded textile articles.

As stated hereinbefore, the evaporation rate of the organic diluent in the blend to be applied to the fibers of the textile article according to the invention should be between 0.01 and 3.5, preferably between 0.1 and 3.0, times the evaporation rate as of sulfolane at 100 C. It has been found that if the evaporation rate of the organic diluent is more than 3.5 times the evaporation rate of sulfolane at 100 C., the diluent may evaporate first from the blend on the fibers of the textile article completely during heating, leaving a large amount of undiluted sulfolane on the fibers of the textile article which may attack the fibers and thereby produce a plasticized mass or even a solution of the fibers. If the evaporation rate of the inert organic diluent is too low, then it may remain on the fibers of the textile article after they have been bonded, making the textile article tacky; therefore, inert diluents are preferred which have an evaporation rate greater than 0.1 times the evaporation rate of the sulfolane at 100 C. Examples of typical inert diluents which are suitable to form blends with sulfolane are given in Table I below which also includes their evaporation rates, expressed both in rug/min. at 100 C. and as a multiple of the evaporation rate of sulfolane at 100 C. The evaporation rates were measured with a Netzch 409 Automatic Thermobalance. For comparative purposes the evaporation rate of unsubstituted sulfolane measured on the same model of the thermobalance is 0.48 mg./min. at 100 C. Thus the maximum and minimum evaporation rates of the organic diluent in the blend are 1.68 and 0.0048 mg./min. at 100 C. respectively measured on this particular model.

1 A product obtained by reacting a mixture of mainly linear aliphatic alcohols with 12 to 15 carbon atoms with 4.3 moles of propylene oxide and 5.6 moles of ethylene oxide. I

2 A product obtained by reacting glycerol with 7 moles of ethylene oxide and 3 moles of propylene oxide.

A particularly preferred diluent for sulfolane is diethylene glycol which has an evaporation rate at 100 C. approximately the same as sulfolane.

The blends to be applied to the fibers of the textile articles may contain components other than sulfolane and an inert organic diluent. The blends may contain water normally in amounts not exceeding 98% by weight, based on the Weight of the blend. The blends may also contain antistats such as cyclohexylamine ethoxylate, corrosion inhibitors such as sodium benzoate and flameproofing agents. Suitable amounts of antistats, corrosion inhibitors and flameproofing agents to be added to the blend are from 1 to 10% by weight, based on the weight of the blend.

The weight ratio of the organic diluent to sulfolane in the blend to be applied to the fibers of the textile article is to some extent dependent on the nature of the fibers. In general, it can be stated that suitable ratios will be found in between 95:5 and 5:95. Preferred ratios of organic diluent to sulfolane to be used for bonding polyacrylonitrile fibers are from 40:60 to 10:90. Preferred ratios for modacrylics are from 10 to 20:80. Preferred ratios for cellulose diacetate fibers are from 90:10 to 70:30. Preferred ratios for cellulose triacetate fibers are from 45:55 to 5:95. Preferred ratios for chlorofibers are from 70:30 to 5:95.

A stated hereinbefore, the instant process may be used to bond the fibers of woven, non-woven, knitted or tufted textile articles. Examples of non-Woven textile articles are yarns, slivers, laps, fleeces, tows, batts, and felts.

One particularly preferred embodiment of the invention is concerned with through-bonding non-woven textile articles. According to this aspect of the invention a process for through-bonding the fibers of a non-woven textile article comprises applying a blend of a sulfolane and an organic diluent to some or all of the fibers throughout the thickness of the non-woven textile article either before or after the fibers have been made up into the textile article and heating the textile article so as to bond the fibers, wherein the fibers and the organic diluent are as hereinbefore defined.

This embodiment of the invention is suitable for through-bonding a batt of fibers to produce a wadding and is particularly suitable for through-bonding a batt of modacrylic or cellulose ester fibers.

Batts of fibers are prepared in a conventional wadding plant by the process described hereinbelow. After a bale of staple textile fibers is opened in a wadding plant, the fibers are converted to webs of fibers either by carding the staple fibers, for example, by using the normal cotton or woolen card or a Garnett card, or by air-laying the staple fibers. In the latter process, the fibers are conveyed by a vary high speed air stream to a condenser where a web of fibers is formed which is then discharged for subsequent processing. Batts of fibers are then formed by crosslaying the webs of fibers.

The bonding blend may be applied to the fibers either before or after they have been made up into a batt of fibers. For example, the bonding blend may be sprayed, dripped or padded onto the fibers before carding or after web formation or after batt formation. If the bonding blend is applied to the fibers before batt formation, then it will be substantially evenly distributed throughout the interior fibers of the batt formed therefrom. However, if the bonding blend is applied to the batt of fibers then it may be necessary to force the blend through the batt to ensure that at least some of the fibers throughout the thickness of the batt are treated by the blend. The bonding blend may be applied to the back and/or the front of the batt of fibers and forced through the batt of fibers by means of a stream of compressed air.

The batt, whose internal fibers have been treated with the bonding blend, is then heated to activate the sulfolane in the blend so as to through-bond the batt of fibers and thereby produce a wadding. The batt of fibers may be heated in an oven by passing a hot gas, e.g., air, through the batt.- The temperature at which the batt is heated to activate the sulfolane depends on the type of fiber and is discussed hereinbelow in greater detail. The fibers of the batt which are in contact with each other will be bonded together at their contact points. Clearly, the amount of bonding will depend on the amount of blend applied to the fibers. A small amount of bonding blend will produce a weak through-bonded wadding whereas a large amount will produce a strong through-bonded wadding. Clearly, some of the surface fibers of the batt may also be bonded. A suitable amount of sulfolane in the blend may be found between 0.5 and 35% by weight, based on the weight of the fibers of the textile article, amounts between and 25% by weight being preferred.

The strength of the wadding produced in accordance .with the above embodiment of the invention may be increased by either needle-punching or stitch-bonding the glattaf fibers before or after it is treated with the bonding Another particular embodiment of the invention is concerned with surface-bonding a textile article. According to this aspect of the invention, a process for surface-bonding atextile article comprises applying a blend of sulfolane and an organic diluent to the surface fibers only of a textile article and heating the textile article so as to bond the surface fibers only, wherein the fibers and the organic diluent are as hereinbefore defined.

The surface fibers of textile articles comprising polyacrylonitrile fibers or chlorofibers are advantageously bonded by the above embodiment of the invention. The textile articles comprising these fibers which are surfacebonded' in accordance with this specific embodiment have a better combination of handling characteristics and abrasion resistance than textile articles comprising the above-mentioned fibers surface-bonded by using undiluted sulfolane as the surface-bonding agent. Suitable textile articles which may be surface-bonded are woven articles, such as blankets, and knitted or tufted articles. Non-woven textile articles, such as through-bonded waddings may also be surface-bonded. Surface-bonding textile articles improves the aesthetic appearance of the article and reduces pilling.

The amount of the sulfolane in the blend used to surface-bond textile articles may be between 0.5 and 35% by weight, based on the weight of the fibers of the textile articles preferably between 0.5 and by weight.

The heating of the fibers of the textile article to effect through-bonding or surface-bonding by activating srulfolane is usually done at temperatures above 60 C. for a period of from 0.5 to minutes, it being understood that the temperature should remain below the temperatures at which the fibers begin to lose their useful properties. Preferred bonding temperatures for polyacrylonitrile fibers are from 100m 160? C., preferred temperatures for'bon'ding modacrylic fibers are from 85 to 120 C. For cellulose diacetate, cellulose triacetate and chlorofibers, the preferred heating temperatures are from 75 to 95 C., from 115 to 135 C. and from 60 to 80 C., respectively.

terials or conditions recited therein. Unless otherwise.

noted, parts and percentages are by weight.

Example I A 6 inch x 6 inch x 0.5 inch batt of hand carded Tekl'an 9 denier fibers was placed in a wooden frame with a removable wire mesh at the back and the front. Teklan is a fiber comprising a copolymer of acrylonitrile (approximately 50%) and vinylidene chloride (approximately 50%); it has a specify gravity of approximately 1.36, softens between 80 and 115 C. and has a dry tenacity of from 3.0 to 3.5 gram/denier. The batt was sprayed with 20%by weight, based on the weight of the fibers of a fine mist of a blend comprising parts by weight of diethylene glycol (DEG) and 40 parts by weight of sulfolane. (The blend comprised 8% wt. by weight of sulfolane, based on the weight of the fibers). An air blast was used to force the applied blend homogeneously through the batt of fibers, and thereafter the batt was heated at 90 C. for 10 minutes by passing hot air through the batt in an oven.

The resulting bonding effect was investigated by feel, visual appearance and microscopic investigation and it was shown that the bonding of the fibers in the wadding was quite satisfactory.

Similar experiments were carried out to effect bonding of batts of 9 denier T eklan fibers using a series of different bonding blends in which the weight ratio of di ethylene glycol to sulfolane was 80:20, :25, 70:30, and 55:45. Another bonding blend was tested in which the organic diluent was triethylene glycol employed in a weight ratio to sulfolane of 70:30. These bonding blends were applied in amounts to ensure a concentration of sulfolane on the fibers of between 10 and 20% by weight, based on the weight of the fibers.

.Good bonding was obtained in each experiment.

Example II Batts of 5 denier Verel, 4 denier Kanekalon and 3 denier Dynel fibers were through-bonded with a blend of 60 parts by weight of diethylene glycol and 40 parts by weight of sulfolane in the manner described in Example I. The bonding of the fibers in the waddings proved satisfactory in each individual experiment. Verel is a fiber comprising a copolymer of vinylidene chloride (approximately 40%) and acrylonitrile (approximately 60% It has a specific gravity of 1.37 and has a dry tenacity of from 2.0 and 2.5 gram/denier. Kanekalon is a fiber comprising a copolymer of acrylonitrile and vinyl chloride. Dynel is a fiber comprising a copolymer of vinyl chloride (approximately 60%) and acrylonitrile (approximately 40%). It has a specific gravity of 1.30, softens at approximately 126 C. and has a dry tenacity between 2.0 and 3.5 gram/ denier.

Example III Using the same procedure as described in Example I, batts of 8 denier ,Dicel and 6 denier Tricel were through-bonded using blends of parts of diethylene glycol and 20 parts of sulfolane, and 25 parts of diethylene. glycol and 75 parts of sulfolane respectively. The batt of Dicel fibers was heated at temperature of C. so as to bond the fibers and the batt of Tricel fibers was heated at from to C. so as to bond the fibers. Again good bonding was obtained in each case. Dicel is a cellulose dicacetate fiber having a specific gravity of 1.32, a melting point of 230 C. and a dry tenacity of 1.4 gram/denier. Tricel is a cellulose triacetate fiber having a specific gravity of 1.32, a melting point of from 290 to 300 C; and a dry tenacity of 1.2 gram/denier.

Example IV For the purpose of comparison, the experiment described in Example I was repeated using blends of 60 parts of the diluents listed in Table II and 40 parts of sulfolane. The batts of fibers tested were 9 denier Teklan fibers and all the other conditions described were left unchanged. The waddings produced by throughbonding the batts of fibers by heating them at 90 C. for 10 minutes were not acceptable since they displayed low left, high shrinkage and some signs of fiber attack. A similar unacceptable bonding was also obtained when using undiluted sulfolane as the bonding liquid.

Table II also lists the evaporation rates of the unsuitable diluents expressed both in rug/min. at 100 C. and as a multiple of the evaporation rate of sulfolane (0.48 mg./min.) at 100 C.

TABLE II Evaporation rate (multiple of the evapora- Evaporation tio 11 rate of rate (millisulfolane, gram/min. 0.48 rug/min. Diluent at 100 C.) at 100 C.)

2- 5 3. 50 2. 5 3. 50 2. 5 3. 50 Monoethylene glyco 2. 06 4. l-methyl naphthalene 2. 08 4. 33 Butyldiethylene glycol acetate 1. 87 3. 90 Diphenyl other 1. 80 3.75 O-chloroacetophenone 2. 5. 21 Acetophenone 2. 5 3. 5 Diethyl succinate 2. 5 3. 5

Example V A blend of parts by weight of diethylene glycol and 40 parts by weight of tetramethylene sulfone was sprayed onto the loose surface fibers of a weak through-bonded Teklan wadding. The amount of blend applied to the surface fibers was 2% by weight, based on the weight of the fibers (0.8% wt. of sulfolane, based on weight of fiber). The Wadding was heated in an oven at C. between thin metal plates. The resultant wadding had virtually no loose surface fibers.

Example VI Various bonding blends diluted with water were padded onto samples of red raised pile, Arachne stitch-bonded Courtelle textile articles. The amount of blend and water which remained on the textile articles, i.e., the wet pick-up, was 170% by weight, based on the weight of fibers. The samples were heated in a drying box at C. so as to bond the surface fibers of textile articles. The composition and amount of the blends applied are given in Table III. Courtelle is a polyacrylonitrile fiber. It has a specific gravity of 1.17, softens at C. and has a dry tenacity of from 3.0 to 3.6 gram/ denier.

The degree of surface-bonding was estimated by the Taber wear test (ASTM Dl-64T) which determines the amount of removable fibers on the surface of the textile articles. The results are given in Table III. It can be seen that the surface-bonded samples lost less fibers than the control (Sample 1), i.e., the surface-bonded samples had a greater resistance to pilling. The feel of the samples (handle) was estimated as being very soft, firm, stifi or very stiff. The results are also given in Table III. It can be seen that the samples surface-bonded with a blend according tothe invention have better feel than the samples bonded with sulfolane alone.

The above experiments were repeated on a blue cord upholstery Courtelle textile article. The results are g ven in Table III. Again it can be seen that the samples surface-bonded with a blend of sulfolane and an organic diluent have better feel than the samples surface-bonded with sulfolane alone and that the samples have a greater resistance to pilling than the control (Sample 1).

Example VII Woven Courtelle blankets were surface-bonded in a similar manner as that described in Example VI. The amount of blend and water which remained on the textile article, i.e., the wet pick-up, was 80% by weight, based on weight of fibers. The composition and amount of the blends applied to the blankets are given in Table IV. The feel (handle) of the surfacebonded blankets was estimated and the results are also given in Table IV. Again it can be seen that blankets surface-bonded with a blend of sulfolane and diethylene glycol have a better feel than blankets surface-bonded with sulfolane alone.

TABLE III Amount of Amount of sulfolane blend applied applied to Percentage to fabric fabric Loss in concentra- (percent by (percent by weight of I tion of weight, based weight, based fabric on Blend applied to fabric (weight blend in on weight on weight wear test, Sample reference ratio) Water of fibers) of fibers) percent Handle one 2. 9 Ver of DEG l [sulfolane (30:70) 6. 8 11. 4 8.0 1. 0 Firrh. C DE G/sulfolane (6 8. 8 15. 0 6. 0 2. 4 Very soft. DE G/sulfolane (15:85) 2. 9 5.0 4. 3 0.9 Soft. do. 4.1 7.0 5.9 1.1 Firm. 2 Sulfolane 3. 5 6.0 Very stiff. 7 .d0 2.4 4.0 Do.

1 Diethylene glycol. 2 For comparison.

TABLE IV Amount of Amount of sulfolane blend applied applied to Percentage to fabric fabric (percent concentra- (percent by by weight, I tion of weight, based based on Blend appl ed to fabric blend in on weight weight of Blanket reference (weight ratio) water of fibers) fibers) Handle 1 None Ver 2 DEG 1 /sulfolaue (30:70) 3. 6 2.9 2. 0 Db 3 .do 7. 2 5. 8 4.1 Soft. 4 .do 10. 6 8.5 6.0 Firm. 5 DE G/sulfolaue (60:40) 18. 8 15.0 6.0 Very soft 6 do 31. 2 25. 0 10.0 D0. 7 DEG/sulfolane (15:85) 6.0 4. 8 4. 2 Soft. 8 do 8. 8 7. 0 0.0 -Do. 9 sulfolane 2 7. 5 6. 0 Very stiff.

1 Diethylene glycol.

2 For comparison.

We claim as our invention:

1. In a process for bonding fibers of a textile article by treating said fibers with a blend of sulfolane and an organic compound and heating to eifect bonding, said fibers being selected from the group consisting of polyacrylonitrile, modacrylic, cellulose ester fibers and chlorofibers, the improvement which comprises a blend of from to 95 parts by weight of sulfolane and from 95 to 5 parts by weight of at least one organic diluent, said diluent being inert to the fibers of the textile article, miscible with sulfolane and having an evaporation rate of between 0.01 and 3.50 times the evaporation rate of said sulfolane at 100 C.

2. A process as in claim 1 wherein the textile article is heated at a temperature above 60 C. for a time sufiicient to bond the fibers.

3. A process as in claim 1 wherein the fibers are polyacrylonitrile fibers, the weight ratio of the organic diluent to said sulfolane is between 40: 60 and :90 and the textile article is heated at a temperature of from 100 to 160 C. for a time sufiicient to bond the polyacrylonitrile fibers.

4-. A process as in claim 1 wherein the fibers are modacrylic fibers, the weight ratio of the organic diluent to said sulfolane is from 90: 10 to 20: 80 and the textile article is heated at a temperature of from 85 to 120 C. for a time sufficient to bond the modacrylic fibers.

5. A process as in claim 1 wherein the fibers are cellulose diacetate fibers, the weight ratio of the organic diluent to said sulfolane is from 90: 10 to 70:30 and the textile article is heated at a temperature of from 75 to 95 C. for a time sufiicient to bond the cellulose diacetate fibers.

6. A process as in claim 1 wherein the fibers are cellulose triacetate fibers, the weight ratio of the organic diluent to said sulfolane is from 45 :55 to 5:95 and the textile article is heated at a temperature of from 115 to 135 C. for a time sufiicient to bond the cellulose triacetate fibers.

7. A process as in claim 1 wherein the fibers are chlorofibers, the weight ratio of the organic diluent to the said sulfolane is from :30 to 5:95 and,the textile article is heated at a temperature of from 60 to C. for a time sufficient to bond the chlorofibers.

8. A process as in claim 1 wherein the organic diluent has an evaporation rate of from 0.1 to 3.0 times the evaporation rate of said sulfolane at C.

9. A process as in claim 1 wherein the amount of said sulfolane in the blend is from 0.5 to 35% by weight, based on the Weight of the fibers of the textile article.

10. A process as in claim 1 wherein the fibers of the textile article are through-bonded.

11. A process as in claim 1 wherein the fibers of the textile article are surface-bonded.

12. A process as in claim 1 wherein said sulfolane is tetramethylene sulfone and the organic diluent is diethylene glycol.

References Cited UNITED STATES PATENTS 3,23 6,586 2/ 1966 Humphreys 8l30.1 3,053,609 9/1962 Miller 8--128 FOREIGN PATENTS 993,498 5/1965 Great Britain.

ALFRED L. LEAVITT, Primary Examiner R. A. DAWSON, Assistant Examiner US. Cl. XQR.