JP2007231449A - Acrylic fiber and method for producing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To stably provide an acrylic fiber being rich in lightweight property, heat retaining property and hygroscopic property while keeping high thermal stability and crimp-retaining property without depending on a complicated spinning method. <P>SOLUTION: The acrylic fiber has a plurality of continuous porous parts randomly continuing in the axis direction of the fiber in an axial cross section and has a comb tooth shape alternately having protruded parts and recessed parts continuing in the axis direction of the fiber in a part of a single fiber surface. A method for producing the acrylic fiber comprises using, as a spinning dope, a solution obtained by mixing a solution obtained by dissolving a copolymer composed of ≥90 mol% acrylonitrile and ≤10 mol% unsaturated vinyl compound into an organic solvent with a solution obtained by dissolving a polyether ester block polymer into an organic solvent and then carrying out graft polymerization of the mixture and spinning the drop by a wet spinning method to provide a fiber and then bringing the fiber into contact with an alkali solution. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an acrylic fiber that is excellent in lightness, heat retention, moisture absorption, high-order workability, and capable of stable production, and a method for producing the same.

Acrylic fibers are excellent in color developability and bulkiness, and are widely used in the clothing field, the jewelry field, the interior field, and the like. In recent years, many attempts have been made to impart lightness, heat retention, and hygroscopicity to the consumer's further comfort orientation with respect to acrylic fibers. For example, core-sheath spinning is performed using different polymers or polymers having different copolymerization components in the core part and the sheath part, and the core part and the sheath part are peeled at the interface in the manufacturing process to form a hollow part. (Patent Documents 1, 2, and 3). Further, it has been proposed that cellulose acetate, polyalkylene oxide, etc. are added to the spinning dope, and after spinning, phase separation occurs between the polymers in the stretching process to form microvoids (Patent Documents 4 and 5). However, the core-sheath spinning method requires a high degree of viscosity adjustment between the polymers, and the number of holes in the spinneret is limited in order to obtain good spinnability due to the characteristics of the core-sheath structure. Furthermore, in the method of forming microvoids in the spinning process, the microvoids are thermally unstable, so that sufficient high-temperature treatment cannot be performed during drying and crimping. Thereby, there are concerns about the shape stability and crimp retention of the resulting fiber. In order to improve this, a method using a thiocyanate aqueous solution as a solvent has been proposed (Patent Document 6), but the solvent recovery step becomes complicated.
JP-A-7-70824 (Claims) JP 2002-13029 A (Claims) JP-A-7-90721 (Claims) Japanese Patent Publication No. 60-11124 (Claims) Japanese Patent Publication No. 59-53365 (Claims) Japanese Patent Laid-Open No. 10-238221 (Claims)

  An object of the present invention is to provide a novel acrylic fiber imparted with lightness, heat retention and moisture absorption as fiber functionality, and the fiber is not produced by a special spinning method and is stably produced. It is to provide a method that is possible.

  The present inventors added an alkali-eluting polymer to the spinning dope, stirred and dispersed, and then spun the fiber obtained by spinning in a high-order processing stage to elute the added polymer, It has been found that a special void is formed in the fiber shape. It has also been found that an acrylic fiber rich in lightness, heat retention and moisture absorption can be obtained.

  That is, the present invention has a plurality of and random voids (porous) in the fiber axis cross section in the fiber axis cross section, and alternately has convex portions and concave portions continuous in the fiber axis direction on a part of the single fiber surface. It is an acrylic fiber characterized by having a comb shape, and further a polyether ester in a solution in which a copolymer of 90 mol% or more of acrylonitrile and 10 mol% or less of an unsaturated vinyl compound is dissolved in an organic solvent. A solution obtained by mixing a solution obtained by dissolving a block polymer in the same organic solvent and graft polymerization is used as a spinning stock solution to obtain a fiber by spinning with a wet spinning method, and the fiber is then contacted with an alkaline solution. The method for producing acrylic fiber according to claim 1.

  Thus, according to the present invention, it is possible to stably and stably obtain acrylic fibers having high porosity, light weight, heat retention, and moisture absorption, regardless of complicated spinning methods.

  The acrylic fiber of the present invention was graft polymerized by mixing a polyether ester block polymer in a solution in which a copolymer of 90 mol% or more of acrylonitrile and 10 mol% or less of an unsaturated vinyl compound was dissolved in an organic solvent. It is obtained by spinning a solution as a spinning stock solution by a wet spinning method.

  That is, the acrylic fiber of the present invention can be obtained by adding an alkali-eluting polymer to an acrylic polymer. The acrylic polymer used in the present invention is a polymer composed of at least 90 mol% acrylonitrile (hereinafter referred to as AN), and can be copolymerized with other copolymerizable unsaturated vinyl compounds within 10 mol%. A single polymer can be used without copolymerization.

  The copolymer component contained in the AN polymer includes acrylic acid, methacrylic acid or esters thereof, acrylamide, methacrylamide, vinyl acetate, vinyl chloride, vinylidene chloride and vinyl sulfonic acid, acrylic sulfonic acid, methallyl sulfone. Acid, unsaturated sulfonic acid such as P-styrene sulfonic acid, or acidic monomers such as salts thereof. The copolymerization rate of the vinyl monomer having a sulfonic acid group is usually 0.2 to 0.7 mol%, preferably 0.3 to 0.5 mol%. If it is less than 0.2 mol%, the dyeability is poor. On the other hand, if it exceeds 0.7 mol%, the drawability tends to deteriorate or the single yarn tends to stick. The copolymerization ratio of the neutral monomer is usually 2 to 7 mol%, preferably 3 to 6 mol%.

  The polymerization method of the acrylic polymer used in the present invention may be any of suspension polymerization method, emulsion polymerization method, solution polymerization method, etc., but the effect is particularly remarkable in dimethyl sulfoxide (hereinafter referred to as DMSO) type wet spinning as an organic solvent. Therefore, the polymerization method is preferably solution polymerization using DMSO.

  The alkali-eluting polymer used in the present invention is not particularly limited as long as the graft polymerization of AN is possible, but it is preferable to select a polyether ester as the alkali-eluting polymer. Examples of the polyester component include ester compounds composed of adipic acid, azelaic acid and ethylene glycol, and examples of the polyether component include polyethylene glycol. The polyether ester is preferably a block polymer. A polymer comprising these two components is dissolved in the same organic solvent as the AN polymer, and AN is added and mixed to carry out graft polymerization. An AN polymer coexists in the polymerization solution thus obtained. Such a polymerization solution is used as a spinning dope. The addition amount of the polyetherester block polymer at this time is 5 to 40% by weight, preferably 25 to 30% by weight, based on the whole spinning dope.

  Water coagulation can be imparted by graft polymerization of acrylonitrile to the polyether ester block polymer in an organic solvent. This makes it possible to form a fiber shape together with the acrylic copolymer without the polyether ester block polymer eluting in the coagulation bath and without generating microvoids in the production process.

  The polymer concentration as the spinning dope is preferably 20 to 25% by weight. When the polymer concentration is less than 20% by weight, the resulting fiber is devitrified and gloss is lost, and color developability is lowered. On the other hand, when the polymer concentration exceeds 25% by weight, the spinnability is remarkably deteriorated. The spinning dope thus prepared is spun using a normal wet spinning apparatus. The spinning bath is preferably an organic solvent such as DMSO, dimethylformamide, or dimethylacetamide, particularly a DMSO aqueous solution.

  When the spinning dope is spun into a DMSO aqueous solution, the spinning draft is usually in the range of 1.5 to 2.2, preferably 1.75 to 2.05. If the spinning draft is less than 1.5, the yarn from the die to the take-up roller will loosen, and the yarn will sway due to the turbulent flow of the coagulation bath liquid, and the yarn will break at the die surface, and if the spinning draft exceeds 2.2, the yarn Is not preferable because the yarn is cut too much on the base.

  As the coagulation bath concentration, a high concentration bath containing 55 to 75% by weight, preferably 57 to 65% by weight of the above-mentioned solvent is desirable. The coagulation bath temperature is generally 30 to 50 ° C., preferably 35 to 45 ° C. When the coagulation bath concentration is high, by setting the coagulation bath temperature relatively low, it is easy to obtain a fiber cross section close to a perfect circle, and the surface smoothness becomes good. The cross-sectional shape of the fiber is not particularly limited, and may be an irregular cross-section.

  In addition to the above coagulation bath conditions, the stock solution temperature is preferably in the range of 60 to 90 ° C, preferably 70 to 80 ° C, and the spinning draft is in the range of 1.75 to 2.05. The coagulated yarn thus prepared is stretched 3.5 to 5 times, preferably 4.0 to 4.5 times in a DMSO aqueous solution. If the draw ratio is less than 3.5, the spinning operability is lowered. The drawn yarn is subjected to removal of the solvent contained in the yarn in warm water, for example, water at 40 to 60 ° C., and then the shrinkage is 5% under dry heat of 150 ° C. or more, preferably 155 to 165 ° C. Hereinafter, drying / densification tension heat treatment is preferably performed while maintaining a shrinkage rate of 0 to 3%. In addition, the densified fiber is subjected to non-tensile heat treatment at a temperature of at least 160 ° C., thereby reducing the entanglement between yarns due to shrinkage and suppressing the occurrence of pilling. In addition, although drying densification and tension free heat processing are normally performed with a hot air dryer, without isolate | separating, you may use the method of isolate | separating and adding a stress free heat processing.

  Thereafter, the acrylic fiber is obtained as a cut or tow of any length through crimping, heat setting, and drying. The obtained fiber is immersed and stirred in an alkaline aqueous solution by high-order processing to elute an alkali-soluble component. This is called alkali treatment. Alkali treatment in high-order processing is not limited by the shape of the acrylic fiber, such as cut or tow shape.

  The conditions for the alkali treatment are as follows: 0.03-6.0 wt% NaOH aqueous solution, temperature 30-90 ° C., treatment time 10-180 minutes, preferably 0.3 wt% NaOH aqueous solution, temperature 60 ° C., treatment time 60 minutes. Good degree. If the alkali concentration is high, the acrylic fiber may be yellowed. The same applies to the case where the temperature is high and the processing time is long.

  After the treatment, it is washed with water for about 10 minutes and then air-dried to obtain an acrylic fiber having a porosity of 15 to 25% and having excellent lightness, heat retention and moisture absorption.

  Thus, the fiber of the present invention is obtained. The fiber of the present invention has plural and random voids (porous) continuously in the fiber axis direction on the fiber axis cross section, and alternately has convex portions and concave portions continuous in the fiber axis direction on a part of the single fiber surface. It has a comb shape. That is, it has a void (porous) in the fiber axis, that is, in the longitudinal direction. The voids are formed long along the fiber axis direction, and a plurality of the voids are present in the fiber axis cross section and are present at random. Moreover, the fiber of this invention forms the comb shape which has the convex part and recessed part which continued to the fiber-axis direction alternately in a part of surface of a short fiber. The lightness, heat retention, and hygroscopicity which were excellent in combination with the voids and the comb structure can be achieved.

  In the fiber of the present invention, the porosity is preferably 1 to 30%. Here, the porosity is calculated by calculating the area of the void portion from a cross-sectional photograph perpendicular to the fiber axis and occupying the total cross-sectional area.

  Hereinafter, the present invention will be specifically described by showing Examples and Comparative Examples, but the present invention is not limited to these. The lightness, heat retention, and hygroscopicity in Examples and Comparative Examples were measured based on the following methods.

Lightweight The lightness was quantitatively evaluated by the weight loss rate before and after alkali treatment. The method for calculating the weight loss rate was performed based on the following formula.
Polymerization weight loss rate = (M ₁ −M ₂ ) / M ₁ × 100
M ₁ : absolute dry weight (g) before alkali treatment
M ₂ : Absolute dry weight after alkali treatment (g)
The absolutely dry weight is the weight dried for 8 hours by a vacuum dryer (80 ° C.).

Porosity The porosity was calculated based on the following formula.
Take a cross-sectional photograph perpendicular to the fiber axis at any location of the fiber of the present invention after alkali treatment (magnification 3000 times), calculate the area of the void in the photograph by integration, and calculate the ratio to the total cross-sectional area did. The average of the respective ratios at 20 arbitrary locations was defined as the porosity.
Porosity = A / B x 100
A: Cross-sectional area of void portion calculated by diagram integration B: Cross-sectional area perpendicular to fiber axis.

Thermal insulation The thermal insulation was evaluated by the claw (CLO) value. 1CLO is necessary for an adult male who is sitting on a chair and resting in an atmosphere with an air temperature of 21.2 ° C, humidity of 50%, and wind speed of 10 cm / s to continue a comfortable condition with an average skin temperature of 33 ° C. It is defined as the thermal resistance value of clothes. Therefore, it shows that it is excellent in heat retention, so that this figure is high. A sample sample is a sample prepared using the inventive fiber after alkali treatment (cylindrical knitting made using 30th spun yarn obtained by blending and spinning the fiber and cotton at a ratio of 80:20. CLO value was measured using a precise rapid thermophysical property measuring apparatus using a knitted fabric with a weight of 210 g / m ² ).

Hygroscopicity Hygroscopicity was quantitatively evaluated using the moisture absorption rate (ΔMR) defined by the following equation. The same sample used for evaluation of heat retention was used.
ΔMR = (N ₂ −N ₁ ) / N ₀
N ₀ : Absolute dry weight of the sample (g)
N ₁ : Sample weight (g) in an atmosphere of 20 ° C. × 65% RH
N ₂ : Sample weight (g) under an atmosphere of 30 ° C. × 95% RH.

Example 1
As a copolymerization component of AN, methyl acrylate and sodium methallyl sulfonate were mixed at a molar ratio of 95.5 / 4.2 / 0.3, and each was prepared in a DMSO solvent. A polymerization initiator is added to the solution, the temperature is adjusted based on the polymerization conditions, and polymerization is performed to obtain a polymerization stock solution A of AN polymer. Separately, an ester compound composed of adipic acid, azelaic acid and ethylene glycol and polyethylene glycol were dissolved in DMSO and graft polymerized with AN to obtain a copolymer stock solution B of polyether ester and AN. Polymerization stock solution A having a polymer concentration of 23% and polymerization stock solution B having a polymer concentration of 22% were added at a ratio of 8: 2. As a result, a spinning dope having a polymer concentration of 22.8% by weight was obtained.

  The obtained spinning dope was discharged from a spinneret into a DMSO aqueous solution having a concentration of 65% and a temperature of 35 ° C., and subjected to water washing, stretching, drying, and heat treatment according to a conventional method to obtain 2.2 DTEX acrylic fibers. When carrying out the spinning, there was no trouble such as clogging of the base or yarn breakage, and the spinnability was stable. The obtained fiber is immersed and stirred in a sodium hydroxide aqueous solution having a concentration of 0.3 wt% NaOH aqueous solution and subjected to an alkali treatment, so that the alkali-soluble polymer is eluted and has a void inside the fiber. The fiber of the present invention was obtained. A photograph of the shape of this fiber is shown in FIG. The weight loss rate of this fiber was 23 wt%. This fiber and cotton were blended at a ratio of 80:20 to obtain 30th spun yarn. Using this spun yarn, a sample specimen with a fabric-like cylindrical knitted fabric shown in Table 1 was prepared, and the weight loss rate, heat retention, and moisture absorption were measured. The results are shown in Table 1.

Example 2
Using the polymerization stock solutions A and B prepared in Example 1, the polymer concentration of the polymerization stock solution A was set to 22.4%, and the polymer concentration of the stock solution B was added to 20%. As a result, a spinning solution having a polymer concentration of 21.5% by weight was obtained. Using the obtained spinning dope, a cylindrical knitted sample sample was prepared in the same manner as in Example 1, and the evaluation measurements shown in Table 1 were performed. The results are shown in Table 1.

Comparative Example 1
Acrylic fibers (fineness: 2.2DTEX) consisting only of AN and cotton were mixed at a ratio of 80:20 to obtain 30th spun yarn. Using this spun yarn, a cylindrical knitted fabric sample was prepared in the same manner as in Example 1, and the evaluation measurements shown in Table 1 were performed. The results are shown in Table 1.

Comparative Example 2
PET fiber (fineness 2.2 DTEX) and cotton are blended at a ratio of 80:20 to obtain 30th spun yarn. Using this spun yarn, a cylindrical knitted fabric sample was prepared in the same manner as in Example 1, and the evaluation measurements shown in Table 1 were performed. The results are shown in Table 1.

Comparative Example 3
Using a 30th spun yarn using 100% by weight of cotton, a cylindrical knitted fabric sample was prepared in the same manner as in Example 1, and the evaluation measurements shown in Table 1 were performed. The results are shown in Table 1.

  Since the knitted fabric obtained from the fiber of the present invention has the function of the fiber, it can be applied to a wide range of fields such as innerwear, lining, and materials.

A photograph (magnification 3000 times) showing the shape of the fiber as seen from an oblique section perpendicular to the fiber axis of the acrylic fiber produced in Example 1

Claims (4)

  Having a plurality of and random voids (porous) in the fiber axis direction on the fiber axis cross section, and a comb-like shape having alternately convex portions and concave portions continuous in the fiber axis direction on a part of the single fiber surface Characteristic acrylic fiber.   The acrylic fiber according to claim 1, wherein the fiber has a porosity of 1 to 30%.   Grafting is carried out by mixing a solution in which a copolymer of 90 mol% or more of acrylonitrile and 10 mol% or less of an unsaturated vinyl compound is dissolved in an organic solvent with a solution in which a polyether ester block polymer is dissolved in the organic solvent. 2. The method for producing acrylic fiber according to claim 1, wherein wet spinning is performed using the polymerized solution as a spinning solution, and the obtained fiber is immersed and stirred in an aqueous alkali solution.   A textile product comprising the acrylic fiber according to claim 1 or 2.

Images