JPH0742605B2 - Method for producing acrylic fiber - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for producing an acrylic fiber, and more specifically, an acrylic resin that prevents sticking of a fiber obtained by spinning by a wet or dry-wet spinning method. The present invention relates to a method for producing a system fiber.

[Prior Art and its Problems] Acrylic fibers are precursor fibers of high-strength carbon fibers (hereinafter,
It's called a precursor. Widely used as).

On the other hand, the high-strength carbon fiber is a material having a high elastic modulus, and its strength is easily affected by minute scratches.

However, in the fiber obtained by the conventional manufacturing method, particularly the dry-wet spinning method, the surface of the fiber is smooth, so that the fiber easily adheres, so-called sticking, and the strength of the carbon fiber is significantly reduced. Has become.

Therefore, as a method of preventing the fibers from sticking, for example, a method of improving the polymer in the spinning dope (JP-A-60-167919).
(See Japanese Patent Laid-Open Publication No. 60-204203), a method of preventing sticking in a spinning nozzle or a coagulation bath by using a surfactant (see Japanese Patent Laid-Open No. 60-24203), and a method of applying various silicone oils after densification by drying (Japanese Laid-Open Patent Publication No. 61-62 -83373), a method of dispersing the fibers constituting the fiber bundle by an external force such as wind (Japanese Patent Laid-Open No. 61-2).
Various methods have been proposed.

However, in these methods, sticking still occurs, and it is difficult to say that the anti-sticking curing is sufficient.

Therefore, under the present circumstances, there is a demand for a method for producing an acrylic fiber having a better anti-sticking effect.

[Object of the Invention] An object of the present invention is to meet such a demand, and has an excellent effect of preventing fiber sticking regardless of whether it is a dry-wet spinning method or a wet spinning method. For example, the production of a precursor on a high-strength carbon crosspiece. An object of the present invention is to provide a method for producing an acrylic fiber that can be suitably used for the above.

[Means for Achieving the Object] As a result of earnest studies by the inventor in order to achieve the object, in the manufacturing process of the acrylic fiber, at least after washing with water and before hot-water drawing. It has been found that, when silicone oil is added to the above, it is possible to provide a method for producing an acrylic fiber which has an excellent effect of preventing the fiber from sticking and can be suitably used for producing a precursor of high-strength carbon fiber. The invention was reached.

That is, the outline of the present invention is, in a method for producing an acrylic fiber from an acrylic polymer solution, at least a fiber obtained by spinning the acrylic polymer solution in a coagulation bath is washed with water, and then the fiber is silicone-treated. A method for producing an acrylic fiber, which comprises applying oil and subsequently performing hot water drawing.

As the acrylic polymer solution, for example, a polymer solution obtained by polymerizing acrylonitrile or acrylonitrile and another vinyl compound monomer in a concentrated zinc chloride solution having a hydrogen chloride content of 0.01 to 5 wt% can be preferably used. .

The monomer used for the polymerization can be used with acrylonitrile 100%, but in order to improve operability, acrylonitrile is 85% or more, preferably 90% or more, and other vinyl compounds are preferably used as a monomer for copolymerization. . Preferred other vinyl compounds include, for example, acrylic acid, methacrylonitrile, methacrylic acid, itaconic acid,
Examples thereof include crotonic acid, vinyl acetate, acrylamide, methyl acrylate, methyl methacrylate, pastyrene sulfonic acid, p-styrene sulfonic acid ester, allyl sulfonic acid, methallyl sulfonic acid and metal salts thereof, or a mixture thereof.

The solvent used for the preparation of the spinning dope is a concentrated aqueous solution of a rhodanic salt such as rhodanesoda, potassium rhodan, ammonium rhodan, and calcium rhodan; a concentrated aqueous solution of an inorganic salt such as zinc chloride or lithium chloride; an inorganic salt such as sulfuric acid or nitric acid. A concentrated aqueous solution of dimethylformamide; an organic solvent such as dimethylformamide (DMF), dimethylacetamide (DMAC), dimethylsulfoxide (DMSO), and the like.

As the polymerization method, for example, dimethyl sulfoxide (DMSO), solution polymerization in an aqueous solution of zinc chloride, aqueous suspension polymerization, or the like can be used as in the conventional method, but in the method of the present invention, preferred is in an aqueous solution of zinc chloride. Solution polymerization.

The spinning solution viscosity is 50 poises or higher, preferably 100 poises or higher, and the polymer concentration is preferably 4-12%. The polymer molecular weight is 50,000 or more, preferably 80,000 to 400,000.

In the method of the present invention, the acrylic polymer solution is wet-spun or dry-wet-spun in a coagulation bath as in the conventional method for producing acrylic fibers.

As the coagulation bath used for the coagulation bath, a dilute aqueous solution of the solvent used for preparing the spinning dope can be used.

For example, in the case of an aqueous zinc chloride solution, the concentration when used as a spinning solution is usually about 50 to 60%, but the concentration when used as a coagulating liquid is preferably 40% or less. The solidification temperature is usually 0 to 35 ° C.

The spinning method is the wet spinning in which the spinning stock solution is directly discharged from the spinning nozzle into the coagulation bath and the spinning stock solution is once discharged into the air or an inert atmosphere from the spinning nozzle, and the discharged fiber bundle is then discharged into the coagulation bath. Although any of dry-wet spinning that guides and solidifies can be adopted, the dry-wet spinning method is preferable from the viewpoint of productivity. Further, when wet spinning and dry wet spinning are compared, sticking is likely to occur in dry wet spinning, so the method of the present invention is particularly effective.

Regardless of which spinning method is used, the gap between the nozzle surface and the coagulation bath surface is preferably 3 to 20 mm.

In the method of the present invention, washing the fibers spun in a coagulation bath with water is the same as in the conventional method for producing acrylic fibers.

That is, usually, in the continuous process, the solvent in the fibers is removed by flowing water in a countercurrent direction to the running direction of the fibers. This washing with water is preferably carried out until the solvent contained in the fiber becomes 2% or less on a dry basis (percentage based on the dry polymer). If 2% or more of the solvent remains,
The silicone oil emulsion may be broken and the silicone oil may not be uniformly applied to the fibers.

An important point in this invention is that after this washing with water,
In addition, the silicone oil is applied to the fiber before hot water drawing.

That is, when hot water drawing is performed, if a large tension is applied at a stage where the fiber temperature does not rise sufficiently, the fibers are likely to stick.

Therefore, when the silicone oil is applied to the fiber after washing with water and before hot water drawing, the prevention of sticking of the fiber is more excellent than in the case where an oil agent is applied after hot water drawing as in the conventional manufacturing method. .

Here, the residual ratio of the solvent of the fiber before applying the silicone oil is 2
% Or less and a moisture content of 200% or more, preferably 4
It is preferably about 00 to 700%. That is, in the method of the present invention, raising the washing temperature to 70 ° C or higher,
After washing with water, if the fibers are compressed or if the moisture content is reduced by drying, the fibers tend to stick, so
It is preferable to apply the silicone oil immediately after leaving the yarn washed with water at room temperature as it is.

As the silicone oil, in addition to dimethylpolysiloxane, methylstyrene-modified silicone oil, olephin-modified silicone oil, polyether-modified silicone oil, alcohol-modified silicone oil, fluorine-modified silicone oil, hydrophilic special modified silicone oil,
Amino-modified silicone oil, mercapto-modified silicone oil, epoxy-modified silicone oil, carboxyl-modified silicone oil, higher fatty acid-modified silicone oil, carnauba-modified silicone oil, amide-modified silicone oil, radical-reactive silicone oil, end-reactive silicone oil, etc. Silicone oils and mixtures thereof can be used.

Among these, amino-modified silicone oil is particularly preferable.

This amino-modified silicone oil can be represented by, for example, the following structural formulas [1] and [2].

(However, in the formulas [1] and [2], m and n represent integers, and R represents a methyl group or a methoxy group.) In addition, although the water-soluble silicone oil may be used, It is also possible to use a water-soluble, so-called emulsion type.

The silicone oil used is usually used at room temperature,
You may use it after cooling or heating. However, the heating temperature when used after heating is usually 70 ° C. or lower. If the temperature exceeds 70 ° C., the heat history given to the fiber may become excessive and the quality of the obtained fiber may be deteriorated.

In the method of the present invention, after applying silicone oil to the fiber, hot water drawing is subsequently carried out.

In hot water drawing, the fiber is usually drawn 2 to 5 times in hot water at a temperature of 70 to 100 ° C. If dry densification is carried out without hot-water drawing, fiber sticking may occur. When emulsion type silicone oil is used, part of the silicone oil may be liberated in hot water, but there is no problem that the liberated silicone oil can be easily removed, rather, This liberation of silicone oil is preferred for removing excess silicone oil.

In the method of this invention, since the silicone oil is removed during hot water drawing, before performing dry densification of the fiber,
It is preferable to apply the oil agent again using silicone oil.

The oil agent used for applying the oil agent is preferably the above-mentioned silicone oil, and is usually used in the form of an emulsion or an aqueous solution having a concentration of 1 to 3%.

Thereafter, drying, heat-sensitive stretching and steam stretching are performed in this order in the same manner as in the conventional manufacturing method.

That is, the drying is preferably carried out by passing the fibers through hot air having a temperature of 80 to 130 ° C. until the water content of the fibers becomes 2% or less.

In the dry heat drawing, usually, the fiber is brought into contact with a hot roll having a temperature of 120 to 140 ° C. and drawn 1.1 to 1.5 times.

Subsequently, steam stretching is carried out. The temperature of steam used for this steam stretching is usually 120 to 150 ° C., and the stretching ratio is usually 2 to 5 times.

In the method of the present invention, the total draw ratio determined by the ratio of the roller speed for drawing fibers from the coagulation bath and the roller speed after vapor drawing, which is the final drawing, is 10 to 30 times, preferably 15 to 30 times.
It is preferable to set it within the range of 25 times.

The acrylic fiber yarn thus obtained has a tensile strength of 60 kg / mm ² or more and an elongation of 10% or more and does not cause sticking between single fibers, so that it can be used, for example, as a composite material or as a precursor of carbon fiber. It can be used suitably.

In particular, when the acrylic fiber obtained by the method of the present invention is used as a precursor of carbon fiber, it may be flame-resistant and carbonized according to a conventional method. It is preferable to treat at a temperature of ~ 250 ° C for 5 minutes or more. Sudden exposure to high temperatures may cause fiber sticking.

[Effects of the Invention] According to the method of the present invention, (1) no sticking occurs in the manufacturing process, and (2) the resulting fiber has excellent mechanical properties, and is preferably used as, for example, a precursor of carbon fiber. (3) In addition, since it can be applied to both the dry-wet spinning method and the wet-spinning method, it is possible to provide a method for producing an acrylic fiber having various advantages such as wide application range. .

EXAMPLES Next, examples and comparative examples of the present invention will be shown, and the present invention will be described more specifically.

Example 1 Polyacrylonitrile / concentrated pure zinc chloride aqueous solution (molecular weight 110,000, 4) consisting of a polymer concentration of 6.5%, methyl acrylate 5%, itaconic acid 2% and residual acrylonitrile.
A spinning stock solution consisting of a solution viscosity at 5 ° C of 310 poise),
It is discharged from a spinning nozzle with a diameter of 0.18 mm and 600 holes, and coagulation bath zinc chloride concentration is 28% and coagulation bath temperature is 5 by dry-wet spinning method.
Spinning was carried out at a temperature of 5 ° C., a discharge linear velocity of 2.5 m / min, a draft rate of 3.0, and a dry length (distance between spinning nozzle tip and coagulation bath liquid surface) of 5 mm.

Next, this fiber thread is 1.
The film was washed while being stretched 5 times, and the amount of zinc chloride was 2% and the moisture content was 500% with respect to the amount of polymer.

Then, the fiber thread was passed through a 1% aqueous emulsion of amino-modified silicone oil [Matsumoto Yushi Co., Ltd., trade name "N-20"] to apply silicone oil.

Then, the fiber yarn is passed through a hot water bath at 90 ° C for 2.
Hot water drawing was performed to give 0 times drawing and 1.5 times drawing at 95 ° C.

Thereafter, according to a conventional method, application of an oil agent, drying, dry heat drawing and steam drawing were performed in this order to obtain an acrylic fiber.

That is, the oil agent was applied by applying a 1% aqueous emulsion of dimethylpolysiloxane [Matsumoto Yushi Co., Ltd., trade name "# 318"] to the yarn.

Drying is carried out by passing the yarn in hot air at 80 ° C.
The water content of the yarn was 1.5%.

The dry heat drawing was carried out by bringing the film into contact with a hot roll at 120 ° C. while giving 1.2 times the drawing.

The steam stretching was carried out by passing through steam at 150 ° C. while giving a 3.7 times stretch.

With respect to the fiber bundles thus obtained, the sticking state was evaluated.

The results are shown in Table 1.

Then, about this acrylic fiber, the temperature from 220 ℃ to 2
The carbon fiber was subjected to flameproofing treatment under the condition that the temperature was raised stepwise to 60 ° C and carbonization treatment under the condition of temperature of 1300 ° C to obtain carbon fiber, and the carbon fiber strength of the obtained carbon fiber was measured.

The results are shown in Table 1.

The evaluation of the stuck state and the measurement of the carbon fiber strength were carried out by the following methods.

Evaluation of stuck state; cut the obtained fiber bundle to a thickness of 1 mm,
Observe the cross section with an optical microscope at 400x magnification,
The number of sticking threads in 100 fiber threads was calculated and expressed as a sticking occurrence rate.

Measurement of carbon fiber strength: According to the resin impregnated strand test method shown in JIS R7601.

(Example 2) In Example 1, a nozzle having a diameter of 0.08 mm was used in place of the nozzle having a diameter of 0.18 mm, and wet spinning was carried out at a discharge linear velocity of 12.7 m / min and a draft rate of 0.5 instead of dry-wet spinning. In addition, it carried out like Example 1 above.

The results are shown in Table 1.

(Example 3) In Example 1, the amino-modified silicone oil [Matsumoto Yushi Co., Ltd., trade name "N-29"] was replaced with dimethylpolysiloxane [Matsumoto Yushi Co., trade name "# 31".
8 ”] was used, and the same procedure as in Example 1 was performed.

The results are shown in Table 1.

(Example 4) In Example 2, instead of amino-modified silicone oil [Matsumoto Yushi Co., Ltd., trade name "N-20"], dimethylpolysiloxane [Matsumoto Yushi Co., trade name "# 31".
8 ”] was used, and the same procedure as in Example 2 was performed.

The results are shown in Table 1.

(Example 5) Polyacrylonitrile / concentrated pure zinc chloride aqueous solution having a polymer concentration of 6.8% (molecular weight 150,000, solution viscosity at 45 ° C 1
050 poise) with a spinning solution of 0.30 mm in diameter and 100 holes
It is discharged from the spinning nozzle of 0, the coagulation bath zinc chloride concentration is 25%, the coagulation bath temperature is 8 ° C, and the discharge linear velocity is 1.
Spinning was carried out at 0 m / min, a draft rate of 8.0, and a dry length (distance between spinning nozzle tip and coagulation bath) of 5 mm.

Next, this fiber thread is 1.
The film was washed while being stretched 1 time to adjust the amount of zinc chloride to the amount of polymer to 0.6% and the water content to 450%.

Then, the fiber thread was passed through a 2% aqueous emulsion of amino-modified silicone oil [Matsumoto Yushi Co., Ltd., trade name "N-110"] to apply silicone oil.

Then, pass the fiber yarn through a hot water bath at 95 ° C. 3.
Hot water drawing was performed to give 0 times drawing.

Thereafter, the fiber yarn was further passed through a 2% aqueous emulsion liquid of dimethylpolysiloxane [Matsumoto Yushi Co., Ltd., trade name "# 318"] to apply an oil agent.

Thereafter, drying, dry heat drawing and steam drawing were carried out in this order according to Example 1 to obtain an acrylic fiber.

The results are shown in Table 1.

(Example 6) In Example 5, the water-soluble amino-modified silicone oil was used as the amino-modified silicone oil [Shin-Etsu Chemical Co., Ltd.].
Manufactured by trade name "KF858"] was performed in the same manner as in Example 5 except that a 1% aqueous solution was used.

The results are shown in Table 1.

(Comparative Example 1) An acrylic fiber was obtained in the same manner as in Example 1 except that the silicone oil was not applied after washing with water and before hot water drawing in Example 1, and this acrylic fiber was used. The adhesion state was evaluated, and the carbon fiber strength of the carbon fiber obtained from this acrylic fiber was measured.

The results are shown in Table 1.

As is clear from Table 1, the rate of sticking and the carbon fiber strength of the acrylic fiber in this comparative example were inferior to those of any of Examples 1 to 6 above.

(Comparative Example 2) In Example 2, an acrylic fiber was obtained in the same manner as in Example 2 except that the silicone oil was not applied after washing with water and before hot water drawing. The adhesion state was evaluated, and the carbon fiber strength of the carbon fiber obtained from this acrylic fiber was measured.

The results are shown in Table 1.

As is clear from Table 1, in this comparative example, as in the case of Comparative Example 1, the sticking occurrence rate of the acrylic fiber and the carbon fiber strength were inferior to any of Examples 1 to 6. .

Claims (2)

[Claims] 1. A method for producing an acrylic fiber from an acrylic polymer solution, which comprises at least spinning a fiber obtained by spinning an acrylic polymer solution in a coagulation bath and washing the fiber with silicone oil. Then, the method for producing an acrylic fiber is characterized by carrying out hot water drawing. 2. The method for producing an acrylic fiber according to claim 1, wherein the spinning is dry-wet spinning.