JP2011168895A - Method for producing acrylic fiber - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing acrylic fibers having excellent anti-pilling property and a fine fineness by a wet spinning method, which has high operation stability and high productivity, and is most suitable as an industrial production process. <P>SOLUTION: In the method for producing anti-pilling fine fineness acrylic fibers comprising an acrylonitrile-based polymer containing 87 wt.% or more of acrylonitrile by a wet spinning method, the relationship between the total fineness and the linear extrusion velocity in a coagulation bath, satisfies the following expression: 2.5≤total fineness/linear extrusion velocity≤15.9, the drawing ratio is 3.5 to 5.0; the relaxation rate after drawn is not more than 5%; the heat treatment temperature under tension is not less than 160°C; and the single fiber fineness of the produced acrylic fibers is 0.3 to 1.0 dtex. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a method for producing anti-pilling fineness acrylic fibers by wet spinning.

  Acrylic fibers have excellent bulkiness similar to wool, texture, and clearness of dyeing, and have a wide range of uses in the clothing field such as knits and jerseys. In addition, fiber products made of acrylic fibers have a drawback that pilling is likely to occur during wearing, and acrylic fibers having excellent anti-pilling properties that hardly cause pilling have been developed. In addition, in recent years, there is a demand for an anti-pill property and a softer texture to the skin, or there is an increasing demand for heat storage properties of fiber fabrics. In order to develop a product that satisfies these required characteristics, it is essential to make the acrylic fiber having anti-pilling property finer.

  However, when the fineness of the anti-pill acrylic fiber is reduced, the amount of fiber that can be produced per fixed time is reduced and the productivity is lowered. In order to compensate for this, it is common to increase the production amount by increasing the spinning speed. However, since acrylic fibers are produced by a wet spinning method, when the spinning stock solution is spun from a spinneret into a coagulation bath solution and coagulated, the accompanying flow generated in the vicinity of the yarn running in the coagulation bath is influenced by the spinning speed. Increases with increasing speed. When the accompanying flow increases, the yarn sway increases and single yarn breakage tends to occur, and the operability deteriorates. As a result, in the case of acrylic fibers, it is difficult to improve productivity by simply increasing the spinning speed. Further, when the spinning speed is simply increased, the dry heat treatment time is shortened, it becomes difficult to sufficiently obtain fiber densification by the dry heat treatment, and the anti-pill property is lowered. Thus, it has been considered difficult to reduce the fineness and maintain productivity while maintaining the excellent anti-pill performance of the anti-pill acrylic fiber.

  Various proposals have heretofore been made as methods for producing anti-pill fine acrylic fibers. Patent Document 1 discloses a method in which the conditions such as the concentration of the spinning dope, the coagulation bath temperature, and the draw ratio are within a specific range in order to produce an anti-pill fine fineness acrylic fiber. Patent Document 2 discloses a specific fiber cross-sectional shape. However, even if these methods are adopted, a decrease in operability due to an increase in spinning speed cannot be avoided. That is, in order to obtain high operational stability, a decrease in productivity is inevitable.

  In order to achieve stable spinning, as disclosed in Patent Document 3, a method has been proposed in which the relationship between the discharge linear velocity and the free discharge linear velocity is optimized to enable stable production. However, even when this method is applied, if the spinning speed is increased, the accompanying flow in the vicinity of the spun yarn increases, turbulence occurs in the coagulation bath, and single yarn breakage increases. Patent Document 4 discloses a rectifier for preventing the coagulation bath from being disturbed by an accompanying flow. Even if this rectifier can suppress the disturbance of the coagulation bath, it is difficult to prevent the problem of insufficient heat treatment due to an increase in the spinning speed and the resulting decrease in the anti-pill property.

JP 2006-176937 A JP 2008-150752 A Japanese Unexamined Patent Publication No. 03-51309 Japanese Patent Laid-Open No. 11-229227

  The object of the present invention is to achieve high operational stability and high productivity when producing acrylic fibers with excellent anti-pilling properties and fineness by wet spinning, and optimal wet spinning for industrial production processes. Is to provide a way.

The present invention is a method for producing an anti-pyruc fine fineness acrylic fiber comprising an acrylonitrile-based polymer containing acrylonitrile at 87% by weight or more by wet spinning, and the relationship between the total fineness in the coagulation bath and the discharge linear velocity is as follows. Satisfying the formula, the draw ratio is 3.5 to 5.0 times, the relaxation rate after drawing is 5% or less, the tension heat treatment temperature is 160 ° C. or more, and the single fiber fineness of the manufactured acrylic fiber is 0.3 to 1.0 dtex It is characterized by being.
2.5 ≦ total fineness / discharge linear velocity ≦ 15.9

The spinneret used here has a spinning stock solution discharge hole number of 5.0 H / mm ² or more per spinneret surface area, the acrylic fiber produced has a fiber strength of 2.65 cN / dtex or more and a knot strength of 1.25 It is preferably ~ 1.90 cN / dtex, and the total fineness is preferably 150 to 210 kilotex.

  Further, as a coagulation bath tank of the wet spinning apparatus to be used, a tank having a shallow depth along the yarn traveling direction is used, and a side cross section along the yarn traveling direction of the tank has a base installation portion as a lower side. It is preferable that the ratio of the upper side to the lower side of the trapezoid is 1: (2.5 to 3.5).

  According to the method of the present invention, it is possible to produce a high-quality acrylic fiber having fineness and excellent anti-pilling properties by a production process having both high productivity and high operational stability. That is, it is possible to achieve both the operational stability and the anti-pill property retention in the fineness, and it is possible to produce the anti-pill fine fineness acrylic fiber with high productivity.

It is vertical direction sectional drawing which shows the outline of the solidification process using the solidification bathtub in this invention (Claim 3). It is vertical direction sectional drawing which shows the outline of the solidification process using the conventional solidification bathtub.

  The anti-pill fine fine acrylic fiber produced in the method of the present invention is an acrylic fiber having excellent anti-pill properties and fine fineness. Specifically, the single yarn fineness is 0.3 to 1.0 dtex, and the anti-pill property is low. This refers to acrylic fiber that is 3.5 or higher.

  The anti-pilling fineness acrylic fiber produced by the method of the present invention is a fiber made of an acrylic polymer containing acrylonitrile in an amount of 87 wt% or more, preferably 90 wt% or more. If the acrylonitrile in the acrylic polymer is less than 87 wt%, the heat resistance as a fiber becomes inferior, so that the heat setability in a tension state preliminarily applied in the yarn production process is remarkably caused by dyeing or steaming in a higher processing step. descend.

  Further, the acrylic polymer may contain 13 wt% or less of a vinyl monomer copolymerizable with acrylonitrile. Examples of vinyl monomers copolymerizable with acrylonitrile include acrylic acid, methacrylic acid or alkyl esters thereof, vinyl acetate, acrylamide, 2-hydroxyethyl methacrylate, glycidyl methacrylate, sodium allyl sulfonate, sodium styrene sulfonate, vinyl chloride. , Vinylidene chloride and the like.

  The polymerization method for producing the acrylic polymer may be any of suspension polymerization method, emulsion polymerization method, solution polymerization method and the like. From the viewpoint of the stability of the polymerization stock solution due to the chain transfer effect and the spinning productivity in wet spinning, it is desirable to polymerize by a solution polymerization method using dimethyl sulfoxide (hereinafter referred to as DMSO) as an organic solvent.

  The spinning dope is a polymer solution in which the acrylic polymer is dissolved in a solvent and an additive is added as necessary, and DMSO may be used as the solvent.

  The polymer concentration in the spinning dope is preferably 20 to 25 wt% in consideration of spinning productivity, stock solution stability, fiber glossiness, and the like. When the polymer concentration is less than 20 wt%, the resulting fiber is devitrified and gloss is lost, and color developability is deteriorated. On the other hand, if the polymer concentration exceeds 25 wt%, the spinnability deteriorates. The spinning dope thus prepared is spun using a normal wet spinning apparatus. In the method of the present invention, the temperature of the spinning dope when discharged from the spinneret is 60 to 80 ° C., preferably 65 to 75 ° C. The spun yarn discharged from the spinneret has a solvent concentration of solvent and water. It is solidified and fiberized in a coagulation bath of 30 to 65 wt% and a temperature of 30 to 60 ° C. When the temperature of the spinning dope is less than 60 ° C., the polymer undissolved portion increases, and accordingly, the filter medium blockage of the filter equipment such as a filter is accelerated. If it is higher than 80 ° C., the deviation from the temperature of the coagulation bath liquid becomes large and temperature control becomes difficult.

  As the coagulation bath, an aqueous solution containing an organic solvent such as DMSO, dimethylformamide, dimethylacetamide, particularly a DMSO aqueous solution is preferable. If the solvent concentration in the coagulation bath is less than 30 wt%, the fiber surface layer is solidified very rapidly, and the internal coagulation does not proceed, so that the spinnability tends to decrease significantly. On the other hand, if it exceeds 65 wt%, the coagulation rate in the coagulation bath becomes slow, and adhesion between fibers tends to occur. On the other hand, when the temperature of the coagulation bath is less than 30 ° C., the spinnability, tensile elongation, and knot elongation increase, and thus the anti-pill property decreases. On the other hand, when the temperature exceeds 60 ° C., the fiber tends to become brittle, and the physical properties of the fiber are deteriorated and the passability in the spinning process is deteriorated.

The spinneret used in wet spinning may be any one having a discharge hole diameter that provides a predetermined single yarn fineness (0.3 to 1.0 dtex). It is preferable from the viewpoint of production efficiency that the number of discharge holes with respect to the die surface area is 5.0 H / mm ² or more. Further, the number of base weights is not particularly limited as long as it has a predetermined total fineness (for example, 150 to 210 kilotex).

  As shown in FIG. 1, the coagulation bath of the wet spinning apparatus used in the method of the present invention is preferably a tank whose depth decreases along the yarn traveling direction. This tank has a trapezoidal shape in which the side cross section along the yarn traveling direction has the base installation side as a lower side, and the side cross section of the coagulating bath liquid becomes a trapezoid. That is, when the base installation site side of the coagulation bath is the lower side and the coagulation bath outlet side is the upper side, the position of the bottom of the bath increases as it approaches the tank exit from the base, and the vertical cross-sectional area of the coagulation liquid decreases. Shape. At this time, it is preferable that the length ratio of the upper side and the lower side satisfies a relationship satisfying 1: (2.5 to 3.5), and particularly preferably 1: 3. At this time, it is preferable that the liquid supply part supplied to the coagulation bath is provided at the bottom of the tank on the side of the base installation where there is little adverse effect on the spun yarn. If the ratio of the upper side / lower side (corresponding to the ratio of the depth of the coagulation bath mouthpiece installation part / tank outlet side) is too small, the concentration of the coagulated liquid supplied and the concentration in the vicinity of the spun yarn will be uneven and large. If it is too much, it is not preferable because it is affected by the turbulent flow caused by the supply liquid.

  The spinning draft when spinning the spinning solution into a coagulation bath (DMSO aqueous solution) is preferably in the range of 1.5 to 2.2. If the spinning draft is less than 1.5, the yarn from the die to the take-up roller is likely to loosen, the yarn swaying due to the turbulent flow of the coagulation bath liquor tends to be large, and the yarn tends to break on the die surface, which is not preferable. Similarly, if the spinning draft exceeds 2.2, the yarn is too tight and the yarn tends to break on the die surface.

  The yarn discharged from the die and solidified is stretched 3.5 to 5.0 times. When the draw ratio is less than 3.5 times, the spinning operability is lowered, and when the draw ratio exceeds 5.0 times, the bending strength of the obtained fibers becomes high and it becomes difficult to obtain fibers having good anti-pill performance. In this way, stretching at an appropriate magnification is an essential condition for exhibiting both high spinning operability and anti-pill properties. The drawn yarn is removed from the solvent contained in the yarn in warm water, for example, water at 40 to 60 ° C., and then at 150 ° C. or more, preferably 155 to 165 ° C. under a dry heat of 5.0% or less. Drying / densification at a relaxation rate and tension heat treatment are performed. If this relaxation rate exceeds 5%, the effect of increasing the fiber orientation in the spinning draft is not maintained, and the bending strength increases and the anti-pill property deteriorates because remarkable orientation relaxation occurs in the high-order processing step. . Further, by subjecting the densified fiber to a tension heat treatment at at least 160 ° C., entanglement between yarns due to shrinkage is reduced, and anti-pill properties are exhibited. The drying densification and the tension heat treatment are usually performed continuously in the same hot air dryer instead of the separated steps, but a separation method may be used.

  In order to develop the anti-pill property in this way, it is necessary to perform drying / densification and tension heat treatment under the above-mentioned appropriate conditions, and further, the ratio of the total fineness and the discharge linear velocity should be within an appropriate range. Is necessary.

In the method of the present invention, it is necessary to set conditions so that the ratio of total fineness / discharge linear velocity is 2.5 to 15.9, and preferably 3.5 to 14.0. Here, the total fineness is the total fineness (Ktex) in the tow stage after the drawing of the acrylic fiber to be produced. The discharge linear velocity is a polymer discharge linear velocity (m / min) from the die in a state where no spinning draft is applied, and can be obtained by the following equation.
Discharge linear velocity (m / min) = spinning speed (m / min) / spinning draft

  When the ratio of the total fineness / discharge linear velocity is less than 2.5, the spinning stability and anti-pilling property due to single yarn breakage deteriorate, and when it exceeds 15.9, the aforementioned deterioration is reduced. Productivity is low and production efficiency is poor.

  By adopting the manufacturing conditions specified in the method of the present invention, the effects of each condition are synergistically maximized, and anti-pill properties, color developability and high productivity are provided. High acrylic fiber can be stably produced with high productivity.

  EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto. The fiber strength, knot strength, operability and anti-pill property in the examples were based on the following methods.

(Fiber strength, nodule strength)
Based on the JIS L1015 chemical fiber staple test method, measure 30 times and determine the average value.

(Operability)
The operability is evaluated from the viewpoints of spinnability and process stability. Spinnability is determined by the presence or absence of yarn breakage on the die surface. The process stability is determined by the presence or absence of single yarn winding around the drawing roller.
○: Both spinnability and process stability are good. △: Either spinnability or process stability is poor. ×: Both spinnability and process stability are poor.

(Anti-pill)
Measured according to JIS L 1076A method. In this measurement method, a test piece of 10cm x 12cm is wound around a special rubber tube in a box with a cork sheet lined inside (a cube with an inner side of 23mm), and is operated for a specified time. A pill is generated by slowly applying the frictional effect of the random contact over time. At this time, no scissors or bending action is applied. It is evaluated based on the results (ICI 5Hr) of a 5-hour test (ICI method) according to JIS L1076 A method. As a test piece, a spun yarn with a count of 1/52 was prepared from a sample acrylic fiber raw cotton, knitted and dyed by a conventional method to form a tubular knitted fabric, and this tubular knitted fabric cut out to a predetermined size was used. It was.

(Example 1)
A spinning stock solution (spinning stock solution concentration 22.0 wt%) was prepared from an acrylonitrile polymer containing 0.3 wt% methacrylsulfonic acid soda and 92.0 wt% acrylonitrile containing methyl acrylate and a solvent (DMSO) as copolymerization components. .

The spinning solution at 77 ° C. was discharged from the spinneret, passed through a coagulation bath (41 ° C., DMSO aqueous solution with a concentration of 68%), coagulated, and taken up with a spinning draft 1.90. At this time, the spinning speed was adjusted while maintaining the spinning draft 1.90 so that the discharge linear speed was 12.0. As the spinneret, a 95,000-hole die having a number of die holes per die surface of 5.3 / mm ² was used. As a tank for the coagulation bath, a trapezoidal tank (the ratio of the upper side / lower side is 1: 3) shown in FIG. 1 was used.

  The coagulated yarn is stretched 4.5 times, relaxed at 4.5%, subjected to tension heat treatment at 165 ° C., and an acrylic fiber tow having a total fineness of 190 kilotex and a single yarn fineness of 0.7 dtex, Acrylic fibers (raw cotton) were produced by cutting to a length of 38 mm.

  The obtained acrylic raw cotton was measured for fiber strength, knot strength, and anti-pill property. The measured values are shown in Table 1 together with the operability evaluation results in the manufacturing process.

(Example 2 and Comparative Examples 1-5)
Except for changing to the manufacturing conditions shown in Table 1 (total fineness, discharge linear velocity, number of nozzle holes, stock solution temperature, draw ratio, relaxation rate, drying heat treatment temperature, coagulation bath cross-sectional shape), the same as in Example 1 An acrylic fiber (raw cotton) was produced as an acrylic fiber tow. The rectangular coagulation bath used in Comparative Examples 2 and 5 has the shape shown in FIG.

  From the results in Table 1, it can be seen that, by satisfying all the conditions specified by the method of the present invention, fine-fine acrylic fibers having excellent anti-pill performance and characteristics can be produced with high operational stability.

The acrylic fiber obtained by the method of the present invention is suitable for producing a fiber product having excellent texture, good quality and performance since it has fineness and excellent anti-pilling property. For example, in the case of using the obtained acrylic fiber alone or blended with cotton, rayon, etc. to produce spun yarn, the anti-pilling effect of the fine-fine acrylic fiber is large, and the underwear that requires anti-pilling properties, etc. It is particularly suitable for use in clothing.

1: coagulation bath tank 2: coagulation bath liquid 3: spinneret 4: coagulated fiber bundle 5: guide roll 6: take-up roller 7: coagulation liquid supply part 8: coagulation liquid overflow outlet

Claims (3)

It is a method for producing an anti-pillar fine-fine acrylic fiber comprising an acrylonitrile-based polymer containing acrylonitrile at 87% by weight or more by wet spinning, and the relationship between the total fineness in the coagulation bath and the discharge linear velocity satisfies the following formula, The draw ratio is 3.5 to 5.0 times, the relaxation rate after drawing is 5% or less, the tension heat treatment temperature is 160 ° C. or more, and the single fiber fineness of the manufactured acrylic fiber is 0.3 to 1.0 dtex. A method for producing an anti-pilling fineness acrylic fiber, which is characterized.
2.5 ≦ total fineness / discharge linear velocity ≦ 15.9 The spinneret discharge hole number in the spinneret is 5.0 H / mm ² or more per spinneret surface area, the fiber strength of the acrylic fiber produced is 2.65 cN / dtex or more, and the knot strength is 1.25 to 1.90 cN / dtex. 2. The method for producing an anti-pilling fineness acrylic fiber according to claim 1, wherein the total fineness is 150 to 210 kilotex A tank having a shallow depth along the yarn running direction is used as a bath for the coagulation bath, and the side cross section along the yarn running direction of the tank is a trapezoid with the base installation side as the lower side, and the upper side of the trapezoid The method for producing an anti-pilling fineness acrylic fiber according to claim 1 or 2, wherein the ratio of the lower side is 1: (2.5 to 3.5).

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