US3737504A - Process for the production of crimped acrylonitrile base yarns with an isopropanol containing bath - Google Patents

Abstract

A PROCESS FO PRODUCING SYNTHETIC YARNS AND FIBERS CONTAINING AT LEAST 50% ACRYLONITRILE COMPRISING: SPINNING AN ACRYLONITRILE POLYMER BASE SLUTION INTO A COAGULANT BATH COMPRISING A SOLVENT FOR THE ACRYLONITRILE AND ISOPROPANOL, DRAWING THE SPUN FILAMENTS IN A SECOND BATH COMPRISING A SOLVENT FOR THE ACRYLONITRILE AND ISOPROPANOL, CUTTING THE WASHING THE FILAMENTS IN THE RELAXED STATE, IMMERSING THE FILAMENTS IN BOILING WATER WHILE IN A RELAXED STATE, ND DRYING THE FILAMENTS IN A RELAXED STATE. FILAMENTS HAVING A TIGHT REVERSIBLE CRIMP ARE PREPARED.

Description

United States Patent 3,737,504 PROCESS FOR THE PRODUCTION OF CRIMPED ACRYLONITRILE BASE YARNS WITH AN ISO- PROPANOL CONTAINING BATH Paul Herrbach, Lyon, and Alain Breton, Paris, France, assignors to CTA-Compagnie Industrielle de Textiles Artificiels et Synthetiques, Paris, France No Drawing. Filed Apr. 22, 1971, Ser. No. 136,566 Claims priority, application France, Apr. 24, 1970, 7014955 Int. Cl. D01f 7/00 U.s. Cl. 264-168 8 Claims ABSTRACT OF THE DISCLOSURE This invention relates to a process for the production of yarns containing at least 50% acrylonitrile having a tight reversible crimp. More particularly, this invention relates to a process for the production of yarns and fibers comprising at least 50% acrylonitrile and having a tight reversible crimp suitable for use in knitted and woven goods.

Synthetic yarns and fibers such as polyamides, polyesters, and polyacrylonitriles may be woven into fabrics having high strength, improved durability, improved launderability, and wrinkle resistance. However, in spite of these superior properties, fabrics produced from synthetic yarns, especially those produced from continuous filament yarns, do not produce products which have asthetic properties similar to natural yarns. For example, fabrics Woven from such filamentary yarns tend to have a slick, cold hand and often have poor luster and cover. A desirable synthetic fabric should have a warm, dry hand, good luster and other properties of a naturally occurring wool-type fabric.

Improvements in this area have generally been attained with mixed shrinkage or bicomponent yarns. Although these fibers tend to crimp and loop and give the fabric a greater bulk and cover, the mixed shrinkage or bicomponent yarns often have undesirable physical properties. The processing of acrylonitrile by a wet spinning process, i.e., the extrusion of an acrylonitrile polymer of copolymer base solution into a coagulant bath, although a desirable method for producing acrylonitrile yarns, does not produce yarns with desirable crimp properties.

There have ben many attempts to produce acrylonitrile yarns with a tight reversible crimp directly from the wet spinning process. U.S. Pat. 3,447,998 discloses a process for producing self-crimping acrylonitrile fibers utilizing the wet spinning method. However, this process utilizes a coagulating bath which does not appreciably penetrate into the fibers. This creates a fiber with a non-uniform skin, a type of sheath-core relationship, therefore causing the fibers to crimp and curl. This process, however, is not suitable for use in producing fibers containing less than 80% acrylonitrile. US. Pat. 3,402,234 discloses a method for obtaining bent fibers by spinning an acrylonitrile polymer solution into a coagulating bath containing t-butyl or t-amyl' alcohol and a polymer solvent. The polymers produced according to the method of this patent, however, are not self-crimping and also have inferior tensile properties,

Patented June 5, 1973 such as tenacity and elongation to rupture. Furthermore, in French Pat. 1,385,441 a method is disclosed for preparing low count vinyl filaments by spinning these polymers into a coagulating bath containing a polymer solvent and a coagulant. However, the process disclosed in this patent also does not produce self-crimping acrylonitrile filaments.

Briefly, it has been found that inherently self-crimping yarns and filaments containing at least 50% acrylonitrile are produced by extruding the acrylonitrile base solution into a coagulating bath containing a solvent for the acrylonitrile, isopropanol, and between 0 and 5% water, drawing the filaments in a second bath containing a solvent for the acrylonitrile, isopropanol and between 0 and 5% water, cutting and washing the filaments in a relaxed state, immersing the filaments in a relaxed state in boiling water, and drying the filaments in a relaxed state.

It is, therefore, the primary object of this invention to provide a process for the production of acrylonitrile based yarns and filaments having a tight reversible crimp.

It is a further object of this invention to provide a process for the production of yarns and filaments containing at least 50% acrylonitrile having a tight reversible cnmp.

It is a still further object of this invention to provide a process for producing acrylonitrile yarns and filaments having a tight reversible crimp by utilizing the wet spinning process.

-It is yet a further object of this invention to provide a process for producing acrylonitrile based yarns and filaments having a tight reversible crimp and superior physical properties.

A still further object of this invention is to provide a process for producing tightly crimped acrylonitrile yarns produced by the wet spinning process utilizing a subsequent treatment bath containing isopropanol.

Still further objects and advantages of the process of the present invention will become more apparent from the following more detailed description thereof.

The process of the present invention, which is suitable for producing crimped filaments, fibers, and yarns from solutions of homopolymers, copolymers, and terpolymers containing at least 50% acrylonitrile, comprises: spinning an acrylonitrile based polymer solution, comprising the acrylonitrile based polymer dissolved in an organic solvent, into a coagulant bath containing an organic solvent for the acrylonitrile polymer, isopropanol, and between 0 and 5% water; drawing the spun filaments in a second bath comprising a solvent for the acrylonitrile polymer, isopropanol, and between 0 and 5% water; cutting and washing the filaments in a relaxed state; immersing the filaments in boiling water in a relaxed state; and drying the filaments in a relaxed state.

The acrylonitrile based polymers suitable for use in the process of the present invention include homopolymers of acrylonitrile, mixture of acrylonitrile polymers with other polymers, copolymers and graft copolymers containing at least 50% by weight acrylonitrile and less than 50% by weight of one or more ethylenically unsaturated monomers copolymerizable with acrylonitrile, such as vinyl chloride, vinyl acetate, vinylidene chloride, acrylic acid, methacrylic acid, esters and amides; methacrylonitrile; compounds containing a carbocyclic acid group such as itacon-ic acid, or a sulphonic acid such as vinylsulphonic compounds, allyl and methallyl sulfonic acids, sulfonated aromatic compounds, for example styrenesulphonic acids and vinyl oxyarene sulfonic acids, vinyl derivatives of basic nature such as vinylpyridiue and its alkyl derivatives, vinyl-dialkylamine ethers, etc.

The acrylonitrile polymer is first dissolved in an organic solvent for the acrylonitrile polymer to form a polymer solution containing from 10 to 30% polymer. The

acrylonitrile based polymers can be dissolved in this solvent for the acrylonitrile utilizing any well known technique. Solvents suitable for use in the process of this invention include dimethylformamide, dimethylacetamide, dimethylsulfoxide, etc. Although the above solvents are preferred, any other solvent which is capable of dissolving the acrylonitrile based polymer may be used in the process of the present invention.

This solution of the acrylonitnile based polymer in the organic solvent is then extruded into a coagulating bath comprising from 37 to 49% by weight of the solvent for the acrylonitrile based polymer, from 61 to 49% by weight of isopropanol, and from to by weight, and preferably from 0.1 to 2%, water. The temperature of this coagulating bath is generally kept below 30 C. and preferably between 0 and 20 C.

After leaving the coagulating bath, the filaments thus formed are then drawn in a bath comprising from 37 to 49% by weight of the solvent for the acrylonitrile based polymer and from 61 to 49% isopropanol. Although this bath may also contain a small proportion of water, i.e., from 0 to 5% water, the water content is preferably from 0.1 to 2% by weight of water. The temperature of the drawing bath is preferably between 80 and 95 C. Although it is not necessary that the composition of the drawing bath and the coagulating bath be the same, itis generally advantageous, and it is preferred, to utilize a drawing lbath having the same composition as the coagulating bath. The rate of drawing in the drawing bath is generally greater than 3X (200%) and preferably between 5x (400%) and X (900%).

Although not necessary for the process of the present invention, the filaments may be slightly drawn after leaving the coagulating bath and before entering the drawing bath at ambient temperature by means of a simple adjustment of the relative speeds of the successive rollers controlling the advance of the filaments. These filaments then are drawn in the drawing bath with the composition as defined above such that the total draw ratio is greater than 3 X, and preferably between 5 X and 10X. Although, as indicated above, the drawing operation may be completed in a single stage or may be a series of'drawing operations, it is preferable to draw the filaments in a continuous manner following the wet spinning operation.

The high drawing rates at these temperatures are possible because of the drawing bath composition and this directly contributes to the production of filaments with improved physical and mechanical properties and in particular to filaments having a tight reversible crimp, very good elongation, and a high tenacity.

Following the drawing step, the filaments are cut into fibers in any conventional manner. The length of these fibers depends entirely upon their later use, and are generally from 20 to 150 mm. These cut fibers are then washed in water at ambient temperature in at least one vat or tub with the water being passed countercurrent to the direction of the fibers to remove the solvent and isopropanol. The solvent and isopropanol, which is recovered, may be recycled for reuse. The washing step may also be performed prior to the cutting operation.

The cut and washed fibers are immersed, while in a relaxed state, in boiling water for about 30 seconds in order to develop the crimp and are then dried by any conventional means, while still in a relaxed state. Alternatively, a thermal treatment may also be employed subsequent to drying utilizing any conventional means in order to further reduce shrinkage of the fibers produced by the present invention.

The fibers produced according to the process of the present invention have a tight, stable and reversible crimp and do not require any further mechanical crimping operations. These fibers also have a good dyeing aifinity and also a good elongation and a high tenacity. These fibers also are particularly Well suited for producing woven and knitted fabrics.

The process "of the present invention will'be further illustrated by means of the following illustrative examples. In the following examples, all parts and percentages are by weight and all temperatures in degrees centigrade. As stated above, these examples are for the purposes of illustration only and are in no way to be taken as limiting.

EXAMPLE 1 A solution containing 21.5% of a tel-polymer of 92.2% acrylonitrile, 7.2% methyl methacrylate, and 0.6% sodium methallyl sulfonate in dimethylformamide' is prepared at 70 C. The specific viscosity of this polymer solution is 0.400 (a 0.2% solution in dimethylformamide at 20 C.). This polymer solution is extruded througha spinneret having 200 holes 0.05 mm. in diameter into a coagulating bath containing 2% water, 48% dimethylformamide, and 50% isopropanol, the temperature of the coagulating bath being 0C. The filaments obtained from this coagulating bath are then drawn in air at ambient temperature to a draw ratio of 2.90 These filaments are then drawn in a bath containing 2% water, 48% dimethylformamide, and 50% isopropanol kept at C.'so as to obtain a total draw ratio of 7.9x. These filaments are then out into fibers 120 mm. long and washed in a relaxed state in water at ambient temperature and flowing countercurrent to the direction of travel of the fibers. The fibers are then immersed in boiling water in a relaxed state so as to form the crimp. The fibers are then dried in a relaxed state at 70 C. and then subjected to a heat treatment in the presence of steam at C. Whilein the relaxed state.

The fibers produced according to this process are tested for their crimping and tensile properties, the individual tests performed and the results of these tests are summarized in Table I below.

The tests conducted on the fibers include:

Tensile properties.elongati0n to rupture and tensile strength measured after treatment, either in the conditioned state, i.e., at 20 C. and 65% humidity, or in the wet state, i.e., after immersion in water.

Crimp properties-level of crimping, frequency of crimping, and permanence are calculated according to the following formulae:

length of uncrimped fiber length of crimped fiber g h of uncrimped fiber X 100: evel Frequency (crimps/centimeter) X 1/2 Following the procedure of Example 1, the same acrylonitrile solution is extruded into a coagulating bath comprising 2% water, 42% dimethylformamide, and 56% isopropanol, maintained at 0 C. The filaments formed are then drawn in a bath containing 2% water, 42% dimethylformamide, and 56% isopropanol maintained at 88 C. to a draw ratio of 8.8x. These filaments are then cut into fibers mm. long and washed in a relaxed state with water at ambient temperature flowing countercurrent with respect to the fibers. These fibers are then im: mersed in boiling water for 30 seconds so as to bring out the self-crimping properties and dried at 70 C.

The tensile and crimping properties measured as indicated in Example 1 are as follows:

A dimethylformamide solution containing 23% of a copolymer comprising 69% acrylonitrile, 30% vinylidene chloride, and 1% potassium vinyloxybenzene sulfonate with a specific viscosity of 0.400, (a 0.2% solution of dimethylformamide at 20 C.), is spun into a coagulating bath comprising 2% water, 38% dimethylformamide, and 60% isopropanol, maintained at 20 C. These filaments are drawn to a draw ratio of 7.9x in a bath with the same composition as the coagulating bath maintained at 90 C. These filaments are then processed as in the previous examples and tested in the same manner. The results of these tests are shown in Table III.

Utilizing the procedure of Example 1 the following acrylonitrile polymers and copolymers are mixed with enough dimethylformamide to form a 20% solution and these solutions are extruded into a coagulating bath containing 2% water, 48% dimethylformamide, and 50% isopropanol, maintained at 0 C. These filaments are also drawn in a drawing bath having the same composition as the coagulating bath kept at 90 C. to a draw ratio of 7.9x. After cutting, Washing, and immersing in boiling water, these fibers are dried at 70 C.

(a) 100% acrylonitrile;

(b) 85% acrylonitrile, methyl methacrylate, 5%

styrene sulfonic acid;

(0) 94% acrylonitrile, 6% vinyl chloride;

(d) 96% acrylonitrile, 4% allyl sulfonic acid;

(e) 52% acrylonitrile, 40% vinylidene chloride, 8% p0- tassium vinyloxybenzene sulfonate;

(f) 60% acrylonitrile, 25% vinyl acetate, methyl methacrylate;

(g) 92% acrylonitrile, 8% vinylpyridene.

Each of the above compositions when treated according to the process of the present invention produces fibers which have excellent crimp level and frequency and the filaments also have excellent tensile properties and count.

EXAMPLE 5 Utilizing the process of Example 1, a solution of a terpolymer containing 94% acrylonitrile, 5% methyl methacrylate, and 1% potassium vinyloxybenzene sulfonic acid, in dimethylformamide is extruded into the following coagulant bath compositions:

(a) 2% water, 37%

panol;

dimethylformamide, 61% isoprowater, 49% dimethylformamide, 49% isopropanol; (c) 1% panol; (d) 1% panol; (e) 0% panol; (f) 0% water, 49%

panol.

The fibers are then drawn in a drawing bath having a composition corresponding to the individual coagulant bath compositions noted above. After this drawing treatment the filaments are cut and Washed, dried and given a heat treatment. Each of these fibers produced has excellent crimp, count and tensile properties.

EXAMPLE 6 A copolymer of acrylonitrile containing 94% acrylonitrile and 6% methyl methacrylate is dissolved in enough of each of the following organic solvents to make a 20% solution:

water, 38% dimethylformamide, 60% isoprowater, 49% dimethylformamide, 50% isoprowater, 39% dimethylformamide, 61% isoprodimethylformamide, 51% isopro- (a) dimethylformamide; (b) dimethylsulfoxide; (c) dimethylacetamide.

These solutions are then extruded into a coagulant bath containing 2% Water, 48% of the respective solvent shown above, and 5 0% isopropanol. These fibers are then treated in accordance with Example 1, using a drawing bath with a composition corresponding to the composition of the coagulant bath. The fibers produced have excellent count, tensile strength and crimp properties.

As can be seen by each of the foregoing examples, the fibers and filaments produced utilizing the process of the present invention have superior crimp properties, and also excellent count and tensile properties.

While the process of the present invention has been described by way of the foregoing specific examples, the process of the present invention is to be in no way limited thereto but is to be construed as broadly as any and all equivalents of the process as defined in the appended claims.

What we claim is: 1. A process for the production of crimped yarns and fibers from solutions of an acrylonitrile polymer selected from homopolymers of acrylonitrile and copolymers of at least 50% acrylonitrile with up to 50% of at least one ethylenically unsaturated monomer copolymerizable therewith comprising:

spinning a solution of said acrylonitrile polymer to form filaments, said solution being formed by dissolving said acrylonitrile polymer in acrylonitrile polymer solvent, into a coagulating bath consisting essentially of from 37 to 49% of said solvent, from 61 to 49% of isopropanol, and from 0 to 2% Water;

drawing the spun filaments to a total draw ratio of from 200 to 900% in a drawing bath consisting essentially of from 37 to 49% of said acrylonitrile polymer solvent, from 61 to 49% of isopropanol, and between 0 and 2% water, said bath maintained at a temperature of from to 95 0.;

cutting and washing the drawn filaments while said filaments are in a relaxed state;

immersing the washed and cut filaments in boiling water while said filaments are in a relaxed state; and drying the washed and treated filaments while in the relaxed state.

2. The process of claim 1 wherein the compositions of the drawing bath and the coagulating bath are substanthe coagulating bath is between 0 and 20 C.

6. The process of claim 4 wherein the temperature of 'the coagulating bath is between 0 and 20C.

7. The process of claim 1 wherein the filaments are drawn prior to the drawing in the drawing bath. 8. The process of claim 1 wherein the solvent is dimethylformamide.

References Cited UNITED STATES PATENTS 2,970,884 2/1951 Stanton et a1 264- 182 3,482,010 12/1969 Yasuietal 264-210F 3,551,547 12/1970 Knudsen 264182 5/1971 Knudsen 264--182 3,402,234 9/1968 n n'vi 61 a1." 264 182 2,249,756 7/1941 Finzel 264Q16'8 2,509,740 5/1950 Miles 8-1301 2,869,975 1/1959 Hare 8-1301 2,869,974 1/1959 Adams 8-1301 3,083,071 3/1963 Wishman 8 130.1 3,233,019 2/1966 Adams 264-168 3,284,871 11/1966 Yano et al-. 264-1 8 3,389,206 6/1968 Jamison 264+l-6'8 3,398,441 8/1968 Adachi et al. -264 168 3,491,179 1/1970 Chinaiet al. 264l68 3,558,763 l/l97l Guyan et a1. 26{l-168 FOREIGN PATENTS 43-6111 3/1968 Japan 264-182 JAY H. WOO, Primary Examiner U.S. c1. X.R.