JP2007126794A - Method for producing porous acrylic fiber - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a porous acrylic fiber giving textile products having large percentage of hollowness and small dispersion of the hollowness, at a high productivity, requiring neither special processing condition nor plant investment. <P>SOLUTION: The method for producing porous acrylic fiber comprises eluting a component (B) from an acrylic fiber by using an alkaline solution, wherein the acrylic fiber comprises a mixture of an acrylonitrile polymer (A) with the component (B) soluble in the alkaline solution. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for producing porous acrylic fibers.

  Acrylic fibers are widely used in clothing and bedding because they are excellent in flexibility, heat retention, color development, weather resistance, and the like. However, the hygroscopicity and water absorption are inferior to those of natural fibers, and in applications such as underwear, socks, and blankets, a feeling of stuffiness and stickiness is generated, resulting in poor commercial value.

  For this reason, many techniques for improving the water absorption of acrylic fibers have been proposed, and one of them is a porous acrylic fiber having a large number of micropores in the cross section of the acrylic fiber. Porous acrylic fibers improve water absorption by capillarity in the internal pores and fine gaps between single fibers, and the absorbed water is present on a vast surface, so water evaporates quickly and quickly dries. There is also an advantage that it is excellent.

  Techniques for producing this porous acrylic fiber have also been proposed in the past. For example, a method in which a water-soluble polymer is added and removed during the yarn-making process (see Patent Document 1), and foreign components are added to form voids at the interface. A method (see Patent Document 2), a method of foaming a low molecular weight additive (see Patent Document 3), and the like are known as known techniques.

  However, these methods have a problem in making them porous during the spinning process. In other words, even if porous acrylic fibers are obtained, the pores are crushed during the subsequent crimping, setting, cutting, carding processes, spinning, weaving, and dyeing processes. There was a problem of impaired expression. In addition, it is possible to maintain the porous shape to a certain extent by improving the processing method, but in that case, special processing conditions are required, making it necessary to invest in equipment and reduce production costs. There was a problem of increasing the cost.

  By the way, the technique which adds an ester-type polymer to an acrylic from the viewpoint of antistatic is proposed (refer patent document 4). However, this technique is an antistatic technique that utilizes the characteristics of an ester-based polymer and is not a technique for making it porous.

Patent Document 1 discloses a technique in which a porous acrylic fiber is produced and then treated with an alkali. This technique is a technique for hydrolyzing the side chain by alkali treatment and introducing a transition metal, and is not a technique for making it porous.
Japanese Patent Laid-Open No. 03-124811 (page 4) Japanese Examined Patent Publication No. 60-011124 (page 4) JP 2001-131821 (page 2) JP 49-116327 A (first page)

  The subject of this invention is providing the manufacturing method of the porous acrylic fiber which can solve the problem of the said prior art.

  The present invention relates to a porous acrylic fiber characterized in that the component (B) is eluted with an alkaline solution from an acrylic fiber comprising a mixture of an acrylonitrile-based polymer (A) and a component (B) that is soluble in an alkaline solution. It is a manufacturing method.

  The porous acrylic fiber manufacturing method of the present invention suppresses the collapse of the holes in the fiber product manufacturing process after the yarn production process, and even when the fiber product is used, the porous acrylic fiber has a high hollow ratio and a small variation in the hollow ratio. can get.

  Hereinafter, the manufacturing method of the porous acrylic fiber of this invention is demonstrated in detail.

  The precursor fiber for forming the porous acrylic fiber used in the present invention comprises a mixture of an acrylonitrile polymer (A) and a component (B) that is soluble in an alkaline solution (hereinafter referred to as an acrylic mixture). Called fiber). The mixed state of both components is that after the component (B) is eluted with an alkaline solution, it becomes porous, that is, a large number of independent pores exist, so that (A) component is sea and (B) component is island in the fiber cross section. Preferably, the sea-island fiber is. Furthermore, it is a sea-island blend fiber having a morphology in which the independent phase composed of component (B) extends in a streak shape in the fiber axis direction and finely disperses to form islands in the sea composed of component (A). However, it is more preferable because a large number of fine holes extending in the fiber axis direction can be formed when a porous acrylic fiber is used.

  The mixing ratio of the acrylonitrile polymer (A) and the component (B) soluble in the alkali solution in the fiber is not sufficiently porous after elution if the component (B) is small, and the cost of raw materials is reduced. Since the addition amount of the component (B) is preferably small, the component (B) is preferably 5 to 50% by weight, more preferably 15 to 40% by weight based on the entire acrylic mixture fiber.

  As the acrylonitrile polymer (A), an acrylonitrile homopolymer and / or an acrylonitrile copolymer of an acrylonitrile monomer and another monomer can be used depending on the application. Examples of other types of monomers include styrene, vinyl toluene, vinyl acetate, vinyl chloride, vinylidene chloride, vinyl bromide, vinylidene bromide, vinyl fluoride, vinylidene fluoride, etc., for the purpose of changing the texture and dyeability of acrylic fibers. Unsaturated monomers, p-sulfophenyl methallyl ether, methallyl sulfonic acid, allyl sulfonic acid, styrene sulfonic acid, 2-acrylamido-2-methylpropane sulfonic acid and alkali metal salts thereof may be mentioned. In addition, when a porous acrylic fiber is used as a carbon fiber precursor, a monomer or acrylamide having a carboxylic acid group or an esterified product thereof for the purpose of accelerating the cyclization of the acrylonitrile-based polymer (A) in the flameproofing step. System monomers may be copolymerized. The ratio of the acrylonitrile monomer to the other monomer can be appropriately selected according to the use of the fiber, but the acrylonitrile monomer in the acrylonitrile copolymer is preferably 50% by weight or more, more preferably 80% by weight or more. By increasing the ratio of the acrylonitrile monomer, the unique properties of the acrylic fiber are maintained even in the porous acrylic fiber.

  In addition, the acrylonitrile-based polymer (A) preferably has a viscosity of 100 to 2000 poise in a 20% by weight dimethyl sulfoxide solution at 45 ° C., which is an index of molecular weight, from the viewpoint of obtaining excellent mechanical properties.

  Component (B) that is soluble in an alkaline solution can be inorganic, organic, low-molecular, or high-polymer as long as it is soluble in an alkaline solution, but it suppresses crushing of pores in the manufacturing process of textile products. In order to achieve this, it is preferable that the product is not eluted in the process of using hot water in yarn production and high-order processing, and zinc oxide and higher fatty acids that are insoluble in water and soluble in alkali are preferably used.

  Furthermore, in order to finely disperse the component (B) in a streak shape in the fiber axis direction, the component (B) is most preferably an ester polymer. There is no particular limitation on the molecular species and molecular weight of the ester polymer as long as it has an ester bond in the main chain, but in order to disperse the ester polymer in a streak form in the yarn production process, The viscosity of the 15 wt% dimethyl sulfoxide solution is preferably 2000 poise or less.

  The ester polymer is more preferably a block polyether ester copolymerized with a polyol, particularly polyalkylene glycol, from the viewpoint of increasing the elution rate with an alkaline solution. Furthermore, for the purpose of improving the compatibility with the acrylonitrile-based polymer (A) and improving the stability of the spinning dope, graft copolymerization of a monomer having good compatibility with the acrylonitrile-based polymer (A) is performed on this block polyether ester. Is most preferred.

  The molecular weight of the polyalkylene glycol copolymerized with the ester-based polymer is preferably 1000 to 20000 from the viewpoint of polymerizability with the polyester, and 3000 in order to make the block polyether ester have a uniform structure in view of solubility in a solvent. It is more preferable to set it to -6000. The mixing ratio of the polyalkylene glycol is preferably 1 to 60% by weight with respect to the total weight of the ester polymer. By setting the content to 1% by weight or more, the decomposition rate during alkali treatment is promoted, and the water resistance of the sea-island fibers obtained by setting the content to 60% by weight or less improves. Specific examples of the polyalkylene glycol include polyethylene glycol, polypropylene glycol, polytetramethylene glycol and the like, and it is particularly preferable to use polyethylene glycol from the viewpoints of polymerizability and alkali decomposability.

  Regarding the composition of the polyester part of the block polyether ester, an aliphatic diol is used for the purpose of suppressing the crystallinity of the ester polymer, improving the solubility in a solvent when preparing the stock solution, and improving the decomposability during alkali treatment. In contrast, aliphatic dicarboxylic acids or a combination of aliphatic dicarboxylic acids and aromatic dicarboxylic acids are preferred. Examples of aliphatic diols include ethylene glycol, propylene glycol, butanediol, pentanediol, hexanediol, neopentyl glycol and the like, and aliphatic dicarboxylic acids include succinic acid, glutaric acid, adipic acid, suberic acid, Examples of azelaic acid, sebacic acid, dodecanedioic acid and aromatic dicarboxylic acid include terephthalic acid, isophthalic acid, orthophthalic acid, 2,6-naphthalenedicarboxylic acid, paraphenylene dicarboxylic acid and the like. Moreover, it is more preferable that a C6 or less aliphatic dicarboxylic acid component is included for the purpose of improving the polymerizability with polyalkylene glycol.

  The monomer that is graft copolymerized with the block polyether ester may be any monomer that is compatible with one or more acrylonitrile-based polymers (A), and examples thereof include acrylonitrile and methyl methacrylate.

  The acrylic fiber comprising the mixture of the acrylonitrile-based polymer (A) of the present invention and the component (B) that is soluble in an alkaline solution has a single yarn fineness of 1.0 to 1.0 from the viewpoint of processability in yarn production and high-order processing. 100 dtex, strength 1.0 to 10 cN / dtex, and elongation 10 to 100% are preferable.

  Such an acrylic blend fiber can be produced by a known method, for example, with respect to a dimethyl sulfoxide solution of an acrylonitrile-based polymer (A) in which the viscosity of a 20 wt% dimethyl sulfoxide solution at 45 ° C. is 100 to 2000 poise. The component (B) soluble in the alkaline solution is mixed so that the fraction of the component (B) is 5 to 50% by weight with respect to the total weight of the components (A) and (B), and 20 It is prepared so that the solution viscosity of the mixed solution at ˜90 ° C. is 20 to 1000 poise. This mixed solution is wet or dry-wet spun into a coagulation bath consisting of a 20 to 80% by weight dimethyl sulfoxide / water mixed solution at 5 to 70 ° C., and the resulting acrylic mixed fiber is taken up at 1 to 100 m / min. It is obtained by stretching two to 20 times in a bath, washing with water and drying, then performing crimping such as stuffing, and further performing steam setting.

  In the present invention, porous acrylic fiber is obtained by eluting component (B) with an alkaline solution from an acrylic mixture fiber comprising a mixture of acrylonitrile-based polymer (A) and component (B) that is soluble in an alkaline solution. Get. According to the present invention, “obtaining porous acrylic fiber by elution” means that the weight of the fiber is reduced by the alkali treatment, and before the alkali treatment, there is substantially no pore in the fiber cross section. It refers to changing to a state in which a large number of pores exist in the fiber cross section after the treatment. In the present invention, substantially no pores are present before the alkali treatment, and the pores are not crushed even if the same yarn production and higher-order processing as those for ordinary acrylic mixed fibers are performed. Depending on the spinning conditions of the acrylic mixture fiber, the acrylic mixture fiber itself may have slight micropores. However, even in the mixed acrylic mixture fiber of the component (A) and the component (B) used in the present invention ( A) Such fine pores may be included in the component portion.

  Further, in the present invention, the component (B) is eluted with an alkaline solution. However, when the component (B) is an ester polymer, the main chain of the ester polymer is hydrolyzed and eluted by the alkali treatment, so that the elution rate is dramatically increased. Improve. This is the most preferable mode because it significantly shortens the processing time compared to known hot water elution of a water-soluble polymer and can greatly reduce equipment, utility, and energy.

  The alkaline solution used in the present invention is a solution having a pH higher than 7, preferably pH 12 or higher, more preferably pH 13 or higher from the viewpoint of improving the processing speed. As the alkaline solution, an aqueous solution of barium hydroxide, calcium hydroxide, copper hydroxide, aluminum hydroxide, ammonia, sodium hydrogen carbonate, or the like can be used, but it is a strong alkali, has a high degree of ionization, and is industrially inexpensive. Most preferably, the aqueous solution is sodium hydroxide or potassium hydroxide.

  Although the density | concentration of an alkaline solution changes with alkali seed | species and the ionization degree of an alkali, from a viewpoint of a processing rate improvement and an industrial yield improvement, 0.03 to 10 weight% is preferable and 0.1 to 6 weight% is more preferable.

  The treatment time with the alkaline solution varies depending on the form of the fiber and the pH of the alkaline solution, but 1 to 180 min is preferable from industrial practicality, and 10 to 120 min is more preferable. The treatment temperature is 10 to 98 ° C., preferably 20 to 70 ° C., from the viewpoint of shortening the elution time and suppressing the evaporation of water from the alkaline solution.

  The alkali treatment can be performed in the form of continuous yarn, crimped yarn, cut cotton, spun yarn, fabric, non-woven fabric or the like. The alkali treatment may be performed by continuously passing the fibers through a bath of an alkaline solution, or may be a batch treatment in which fiber skeins, raw cotton, spun yarn cheese, and fabric are immersed in a liquid bath.

  The process of alkali treatment includes post-yarning, crimping, cutting, spinning, weaving and knitting, after scouring, etc. Subsequent and subsequent steps are preferred.

  The porous fiber obtained in the present invention is a fiber having 50 or more, preferably 100 or more pores in the cross section, and from the viewpoint of improving water absorption, there are pores connected to the fiber surface. preferable. The average value (Dv) of the equivalent circle diameter of each hole is preferably 0.05 μm or more in order to exhibit the function as a hole, and 5.0 μm or less in order to increase the water absorption. The ratio (Dmax / Dv) of the equivalent circle diameter (Dmax) of the pores to the average value (Dv) of the equivalent circle diameter of the pores is 1 to 20, preferably 1 to 10, and has high mechanical properties and water absorption. Is more preferable from the viewpoint that both can be achieved. The hollow ratio expressed as a percentage of the ratio of the total area (Sv) of pores in the cross section of the fiber and the area surrounded by the outer periphery of the single fiber (Sf) is 5 from the viewpoint that both high mechanical properties and water absorption can be achieved. It is preferable that it is -50%, and 10-40% is more preferable. The number of pores in the present invention, the equivalent circle diameter of the pores, the equivalent circle diameter of the largest pore (Dmax), the average value of equivalent circle diameters of the pores (Dv), the area of the pores in the fiber cross section The total (Sv), the area surrounded by the outer periphery of the single fiber (Sf), and the hollow ratio are values determined by the method described in the examples.

  The porous acrylic fiber obtained by the present invention is preferably used for applications such as clothing and bedding, and has a single yarn fineness of 1.0 to 100 dtex, a strength of 1.0 to 10 cN / dtex, and an elongation of 10 to 100%. In addition, since the porous acrylic fiber obtained by this invention does not have a coarse void | hole and consists of a fine void | hole, it is the characteristics that the outstanding intensity | strength is acquired even if it makes it porous.

  The porous acrylic fiber obtained by the present invention has a high hollowness due to a large number of pores, so it is excellent in water-absorbing quick-drying, lightweight heat retention, and has high mechanical properties that can be used as an acrylic fiber. Because there are fine irregularities on the fiber surface due to the communicating part of the fiber, it is excellent in refreshing feeling, and the acrylic side chain is modified by alkali treatment, and the adsorptivity of the cationic dye is also improved. It is suitably used for various applications. Porous acrylic fibers may be used alone, natural fibers such as cotton, hemp and wool, chemical fibers such as rayon and acetate, synthetic fibers with polyester and nylon, blended or mixed, interwoven, and knitted. It is also possible to use it. Examples of applications include foot cleaning mats, towels, dryer canvas, underwear, and socks. Further, by adsorbing a functional agent to the surface of the micropores and porous fibers, it can be used for antibacterial clothing, chemical solution sustained-release materials, cell culture media, and the like.

  In the method for producing the porous acrylic fiber of the present invention, the most suitable example is that a block polyether ester obtained by graft copolymerization of acrylonitrile is used as the component (B) that is soluble in an alkaline solution, and the acrylonitrile polymer (A) component is After obtaining an acrylic mixed fiber in which the sea and the component (B) are islands, and performing crimp processing such as stuffing and steam setting, it is added to a sodium hydroxide aqueous solution having a pH of 12 or more at 20 to 70 ° C. for 5 to 120 minutes. By soaking, a porous acrylic fiber having 50 or more voids in the cross section and a hollowness of 5 to 50% is obtained.

Hereinafter, the present invention will be described in more detail with reference to examples. In addition, each characteristic value in an Example was calculated | required with the following method.
A. Viscosity of Polymer Solution Using a DV-II + Pro VISCOMETER manufactured by BROOKFIELD, the viscosity was measured at a shear rate of 10 to 20 sec ⁻¹ under the condition that the temperature was controlled constant with TC500 manufactured by BROOKFIELD.
B. Measurement of fiber cross-sectional shape and pores After impregnating the sample fiber with epoxy resin, a microtome is used to make an ultrathin slice of the plane perpendicular to the fiber axis (or the plane horizontal to the fiber axis in the case of a longitudinal section), Observation with a transmission electron microscope (Hitachi, Ltd., H-7100FA) at a magnification of 4000 times, the form is observed from the obtained image, and image processing software ( Circular figure separation was performed by Mitani Shoji Co., Ltd. (Winroof), and the following measurements were performed.
Number of holes: The number of holes independent from the observed image was measured.
Equivalent circle diameter of holes: The equivalent circle diameter of each hole was determined by image processing software.
Maximum equivalent circle diameter of holes (Dmax): The largest equivalent circle diameter of holes was adopted.
Minimum equivalent circle diameter (Dmin): The smallest hole equivalent circle diameter was adopted.
Average value of equivalent circle diameters of holes (Dv): The average of equivalent circle diameters of all holes was obtained.
Total area of pores in fiber cross section (Sv): A value obtained by summing the areas of all pores was used.
Area surrounded by the outer periphery of the single fiber (Sf): All the holes in the image were filled, and the area of the portion surrounded by the outer periphery of the fiber was obtained by image processing software.
In addition, the hollow ratio was calculated | required with the following formula | equation.
Hollow ratio (%) = (Sv / Sf) × 100
C. Single fiber fineness, strength, and elongation The single fiber fineness was measured using a Denier Computer manufactured by Search, and the average value of the ten single yarn finenesses was defined as the single fiber fineness. The strength and elongation were measured using Tensilon UTC-100 manufactured by Orientec Co., Ltd. at an initial length of 20 mm and a tensile speed of 20 mm / min, and the average value of five measurements was used as the strength and elongation.
D. Number of crimps The length L (mm) and the number of peaks (M) are measured in a state where a load of 1.8 mg / dtex is applied to a single fiber, and the number of crimps is obtained by the following equation.
Number of crimps (mountain / 25 mm) = M × 25 / L
Example 1
An acrylonitrile polymer (A) composed of 94% by weight of acrylonitrile, 5% by weight of methyl acrylate, and 1% by weight of sodium methallyl sulfonate is polymerized by a solution polymerization method using dimethyl sulfoxide (DMSO) as a solvent. Of 20% by weight in DMSO (S _A ) was obtained. The viscosity of (S _A ) at 45 ° C. was 200 poise.

Next, 12 parts of ethylene glycol was added to 5 parts of adipic acid and 12 parts of azelaic acid, and an esterification reaction was performed to obtain a prepolymer. To this prepolymer, 48 parts of polyethylene glycol (molecular weight 4000) was added and subjected to polycondensation to obtain a block polyether ester composed of polyadipate, polyazelate, and polyethylene glycol. The block polyether ester 100 parts was dissolved in DMSO737 parts, to obtain a 15.0 wt% DMSO solution of the ester-based polymer and 30 parts of acrylonitrile were graft polymerized _{(B) (S} B). The viscosity of (S _B ) was 15 poise at 45 ° C. When the ester polymer (B) obtained by discharging (S _B ) into water was immersed in an aqueous sodium hydroxide solution having a pH of 13.5 at 60 ° C. for 60 minutes, the polymer was completely dissolved, so that the ester polymer ( It can be said that B) is soluble in an alkaline solution.

These were metered and discharged independently by a gear pump so that (S _A ) was 630 g / min and (S _B ) was 360 g / min, and both were mixed by a mixer having 14 stages. The viscosity of the mixed stock solution (S) was 140 poise at 45 ° C. This mixed stock solution (S) was discharged into a coagulation bath composed of a 40 wt% DMSO / water mixed solution at 40 ° C. using a spinneret having a hole diameter of 0.06 mmφ and a hole number of 30000, and coagulated at 5.0 m / min. After drawing, the film was stretched 6.0 times in a two-stage stretching bath composed of a 30 wt% DMSO / water mixed solution at 70 ° C. and a 10 wt% DMSO / water mixed solution at 90 ° C., and then washed with a 25 ° C. water bath. Subsequently, the mixture was passed through a hot drum at 160 ° C. to obtain a 60000 dtex / 30000 f acrylic mixed fiber. This acrylic mixed fiber had a weight ratio of component (A): component (B) of 70:30, single fiber fineness of 2.0 dtex, strength of 2.1 cN / dtex, and elongation of 25%.

  The acrylic mixture fiber was introduced into a stuffing box having an inlet pressure of 0.06 MPa and an outlet pressure of 0.01 MPa, and then steam set at 105 ° C. for 30 minutes using a batch setter. In the cross-sectional observation of the fiber after the steam setting, a sea-island structure in which the component (A) is the sea and the component (B) is the island was observed, but no clear pores were observed. At this point, the acrylic mixture fiber became porous. It wasn't. In addition, in the fiber longitudinal section observation of this fiber, it was confirmed that the (B) component formed an independent island in the sea part of the (A) component, and was stretched and finely dispersed in the fiber axis direction. . This acrylic mixed fiber had a number of crimps of 12 peaks / 25 mm, a single fiber fineness of 2.1 dtex, a strength of 1.8 cN / dtex, and an elongation of 40%.

  Using this acrylic mixture fiber as a skein, a bath ratio of 1: 100 or more is added to a 1.5 wt% (pH 13.5) sodium hydroxide aqueous solution (Marserine PES manufactured by Meisei Chemical Co., Ltd. added to the bath by 0.4 wt%). Soaked at 60 ° C. for 120 min. Before and after the alkali treatment, the weight of the fiber (skein) was reduced by 25 wt%. When the cross section of the fiber after alkali treatment was observed, 190 pores were generated in the cross section to make it porous, and pores communicating with the surface were also seen (the communication holes were pores). Not considered as a part of the outer periphery of a single fiber). The equivalent circle diameter of the pores was 2.9 μm at the maximum (Dmax), 0.072 μm at the minimum (Dmin), 0.54 μm in the average value (Dv), and Dmax / Dv was 5.4. Further, the hollowness was as high as 24% (Table 1).

  Further, this porous acrylic fiber had a single yarn fineness of 1.6 dtex, a strength of 2.3 cN / dtex, and an elongation of 40%, and had excellent mechanical properties.

Examples 2-5
In the same manner as in Example 1, except that the acrylic mixture fiber after the steam setting composed of the component (A) and the component (B) used in Example 1 is changed as shown in Table 1. An alkali treatment was performed. The cross-sectional observation results after treatment are also shown in Table 1, and it can be seen that porous acrylic fibers having a high hollow ratio can be obtained even when the pH, treatment temperature, and treatment time are changed.

Example 6
61 parts of the _{(S A)} that used in Example 1 to give _{(S B)} were charged at a ratio of 14 parts, stirring to mix the stock solution by using a stirring blade (S). The viscosity of this mixed stock solution at 45 ° C. was 170 poise. This mixed stock solution is measured with a gear pump so as to be 7.5 g / min, and is discharged into a coagulation bath composed of a 45 wt% DMSO / water mixed solution at 45 ° C. using a spinneret having a hole diameter of 0.06 mmφ and a hole number of 400. It was solidified, taken up at 6.0 m / min, and stretched 4.0 times in a two-stage stretching bath consisting of a 30 wt% DMSO / water mixed solution at 75 ° C. and a 15 wt% DMSO / water mixed solution at 95 ° C. After that, it was washed with a 25 ° C. water bath and subsequently passed through a 140 ° C. hot drum to obtain 600 dtex / 400 f of acrylic mixed fiber. This acrylic mixture fiber had a weight ratio of component (A): component (B) of 85:15, single fiber fineness of 1.5 dtex, strength of 1.8 cN / dtex, and elongation of 20%.

  The acrylic mixture fiber was introduced into a stuffing box having an inlet pressure of 0.06 MPa and an outlet pressure of 0.01 MPa, and then steam set at 105 ° C. for 45 minutes with a batch setter. In the cross-sectional observation of the fiber after the steam setting, a sea-island structure in which the component (A) is the sea and the component (B) is the island was observed, but no clear pores were observed. At this point, the acrylic mixture fiber became porous. It wasn't. In addition, in the fiber longitudinal section observation of this fiber, it was confirmed that the (B) component formed an independent island in the sea part of the (A) component, and was stretched and finely dispersed in the fiber axis direction. . This acrylic mixed fiber had a number of crimps of 12 peaks / 25 mm, a single fiber fineness of 1.7 dtex, a strength of 1.7 cN / dtex, and an elongation of 22%.

  This acrylic mixture fiber was used as a skein and immersed in the same alkaline solution as in Example 1, and subjected to an alkali treatment at 60 ° C. for 120 min. The weight of the fiber (skein) was reduced by 11 wt% before and after the alkali treatment. When the cross section of the fiber after alkali treatment was observed, 104 pores were generated in the cross section to make it porous, and pores communicating with the surface were also seen. The equivalent circle diameter of the pores was 2.8 μm at the maximum (Dmax), 0.11 μm at the minimum (Dmin), 0.35 μm in average value (Dv), and Dmax / Dv was 8.0. Further, the hollow ratio was as high as 10%.

  Further, this porous acrylic fiber had a single yarn fineness of 1.5 dtex, a strength of 2.0 cN / dtex, and an elongation of 21%, and had excellent mechanical properties.

Comparative Example 1
Polymerization degree of 1,700, a saponification degree of 99 mol% polyvinyl alcohol (PVA) were dissolved in DMSO, and to adjust the PVA of 15 wt% solution of _{(S C).} The viscosity of (S _C ) at 45 ° C. was 2000 poise.

The mixed stock solution (S) was adjusted, knitted, and crimped by the same method as in Example 6 except that this (S _C ) was used instead of (S _B ). The viscosity of the mixed stock solution (S) at 45 ° C. was 1900 poise. The crimped acrylic mixture fiber had a number of crimps of 12 peaks / 25 mm, a single fiber fineness of 1.5 dtex, a strength of 2.1 cN / dtex, and an elongation of 21%. In the cross section observation of the acrylic mixed fiber, no clear sea-island structure was found in the cross section, but 22 holes were present in the cross section. At this time, the equivalent circle diameter of the hole is 0.9 μm at the maximum (Dmax), 0.35 μm at the minimum (Dmin), the average value (Dv) is 0.55 μm, and Dmax / Dv is 1.6. It was. The hollowness was 2.2%.

  This fiber was subjected to alkali treatment in the same manner as in Example 6. The weight reduction before and after the alkali treatment was 0.5 wt%, and the weight was not substantially reduced. When the cross section of the fiber after alkali treatment was observed, 19 holes were found in the cross section, and the equivalent circle diameter of the holes was 1.0 μm at the maximum (Dmax) and at the minimum (Dmin). 0.41 μm, the average value (Dv) was 0.50 μm, Dmax / Dv was 2.0, the hollowness was 2.0%, and no porosity was formed by alkali treatment.

  The PVA used in this experiment is soluble in hot water, and PVA was eluted during the spinning process. Therefore, pores were observed in the acrylic mixed fiber after crimping, but the eluted components remained in the alkali treatment. Since it was not, it is estimated that it was not made porous by alkali treatment.

Example 7
83 parts of the _{(S A)} that used in Example 1, to obtain a charge at a rate of _{(S B)} of 90 parts, stirring to mix the stock solution by using a stirring blade (S). The viscosity of this mixed stock solution at 45 ° C. was 110 poise. This mixed stock solution is measured with a gear pump so as to be 17.3 g / min, a spinneret having a hole diameter of 0.12 mmφ and a hole number of 100 is used, and the take-up speed (roller speed at the coagulation bath) is 6.5 m / min. Yarn making and crimping were performed in the same manner as in Example 6 except that the magnification was 4.6 times. The acrylic mixed fiber after spinning is 1000 dtex / 100f, the weight ratio of the component (A) :( B) is 55:45, the single yarn fineness is 10 dtex, the strength is 1.3 cN / dtex, and the elongation is 30%. there were. The crimped acrylic mixed fiber had a number of crimps of 12/25 mm, a single yarn fineness of 12 dtex, a strength of 1.1 cN / dtex, and an elongation of 34%. In the cross-sectional observation of the fiber after crimping, a sea-island structure in which the component (A) is the sea and the component (B) is the island was observed, but no clear pores were observed. At this point, the acrylic mixture fiber was porous. It was not converted. In addition, in the fiber longitudinal section observation of this fiber, it was confirmed that the (B) component formed an independent island in the sea part of the (A) component, and was stretched and finely dispersed in the fiber axis direction. .

  This acrylic mixture fiber was subjected to alkali treatment in the same manner as in Example 6. Before and after the alkali treatment, the weight of the fiber (skein) was reduced by 36 wt%. When the cross section of the fiber after alkali treatment was observed, 212 pores were generated in the cross section to make it porous, and many holes communicating with the surface were also seen. The equivalent circle diameter of the pores was 4.6 μm at the maximum (Dmax), 0.10 μm at the minimum (Dmin), 0.82 μm in average value (Dv), and Dmax / Dv was 5.6. The hollow ratio was as high as 31%.

  Further, this porous acrylic fiber had a single yarn fineness of 7.7 dtex, a strength of 2.1 cN / dtex, and an elongation of 20%, and had excellent mechanical properties.

Example 8
Polyadipates used in Example 1, Poriazereto, a block polyether ester 15 parts of a polyethylene glycol dissolved in DMSO85 parts (not added acrylonitrile) 15.0 wt% DMSO solution of the ester-based polymer (B) _{(S B} ) The viscosity of (S _B ) at 45 ° C. was 12 poise. Yarn production and crimping were performed in the same manner as in Example 1 except that (S _B ) was used. The viscosity of the mixed stock solution was 130 poise. The acrylic mixed fiber after spinning is 60000 dtex / 30000f, the weight ratio of component (A): component (B) is 70:30, single yarn fineness 2.0 dtex, strength 2.0 cN / dtex, elongation 26 %Met. The crimped acrylic mixed fiber had a number of crimps of 12/25 mm, a single yarn fineness of 2.2 dtex, a strength of 1.9 cN / dtex, and an elongation of 28%. In the cross-sectional observation of the fiber after crimping, a sea-island structure in which the component (A) is the sea and the component (B) is the island was observed, but no clear pores were observed. At this point, the acrylic mixture fiber was porous. It was not converted. In addition, in the fiber longitudinal section observation of this fiber, it was confirmed that the (B) component formed an independent island in the sea part of the (A) component, and was stretched and finely dispersed in the fiber axis direction. .

  This acrylic mixture fiber was subjected to alkali treatment in the same manner as in Example 1. The weight of the fiber (skein) was reduced by 28 wt% before and after the alkali treatment. When the cross section of the fiber after the alkali treatment was observed, 172 pores were generated in the cross section to make it porous, and pores communicating with the surface were also seen. The equivalent circle diameter of the pores was 3.2 μm at the maximum (Dmax), 0.095 μm at the minimum (Dmin), 0.63 μm in average value (Dv), and Dmax / Dv was 5.1. The hollow ratio was as high as 26%.

  Further, this porous acrylic fiber had a single yarn fineness of 1.6 dtex, a strength of 2.3 cN / dtex, and an elongation of 23%, and had excellent mechanical properties.

  The porous acrylic fiber manufacturing method of the present invention enables the porous acrylic fiber having a high hollow ratio and a small variation in the hollow ratio to be produced as a fiber product without requiring special processing conditions and capital investment, and with high productivity. Obtainable. The resulting porous acrylic fiber has excellent water absorption and quick drying, lightweight heat retention, refreshing feeling, and clear color development. By adsorbing the functional agent on the surface, it can be suitably used for antibacterial clothing, drug solution sustained-release materials, cell culture media and the like.

Claims (2)

  A method for producing a porous acrylic fiber, wherein the component (B) is eluted with an alkaline solution from an acrylic fiber comprising a mixture of an acrylonitrile-based polymer (A) and a component (B) that is soluble in an alkaline solution. .   The method for producing a porous acrylic fiber according to claim 1, wherein the component (B) soluble in the alkaline solution is an ester polymer.