JP2000290832A - Porous fiber and method for producing the same - Google Patents

Abstract

(57) [Summary] [Problem] To produce industrially and safely a porous fiber excellent in bulkiness. [Solution] After spinning a thermoplastic polymer obtained by adding a resin having a water absorbing property, heat treatment is performed. A method for producing a porous fiber, wherein pores are developed by performing the method. In the case where the spinning of the thermoplastic polymer is a wet spinning, it is achieved by performing a wet heat treatment after a dry and dense treatment after the spinning.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fiber excellent in bulkiness and suitable for use in pile products such as clothing and toys.

[0002]

2. Description of the Related Art Conventionally, as a method for producing a porous fiber, Japanese Patent Application Laid-Open No. 56-4711 discloses a method of spinning a polymer comprising cellulose acetate, a vinyl polymer and an acrylic polymer, and forming a capillary by phase separation. Although a method of expressing pores has been proposed, since pores are expressed during stretching,
This has caused a reduction in spinning stability such as yarn breakage. As a method for producing a fiber having excellent bulkiness, a method has been proposed in which a low-boiling compound is added to JP-A-61-102408 and heat treatment is performed to develop vacancies. On the other hand, a method of generating pores by performing a rapid heat treatment after mild drying on -28014 has been proposed, but it has been difficult to mass-produce industrially.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to safely produce industrially a porous fiber having excellent bulkiness.

[0004]

That is, the present invention provides a porous fiber characterized in that pores are developed by spinning a thermoplastic polymer to which a resin having a water absorbing property is added and then performing a heat treatment. When the thermoplastic polymer is wet-spun, it is preferable to perform a wet heat treatment after the dry and dense treatment after the spinning.

On the other hand, when the spinning of the thermoplastic polymer is dry spinning or melt spinning, it is preferable to perform a wet heat treatment after spinning.

[0006] The water swelling degree of a resin having water absorbing performance is 1
It is preferably at least 00 cc / g, and the resin may be a resin containing an acrylate compound or a resin containing a vinyl alcohol compound. In this case, the amount of the resin having water absorbing performance is preferably 0.5 to 30 parts by weight based on 100 parts by weight of the thermoplastic polymer.

[0007] Further, the thermoplastic polymer is preferably a polymer containing acrylonitrile.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.
In the present invention, the resin having water absorbing performance (hereinafter, abbreviated as a water absorbing resin) includes starch, cellulose, acrylate, sulfonic acid, acrylic acid graft, acrylic acid copolymer, Grade ammonium salt, vinyl alcohol, acrylamide, oxyethylene, polyacrylate, isobutylene / maleate copolymer, starch / acrylate graft, vinyl alcohol / acrylate copolymer, polyvinyl Homopolymers or copolymers such as alcohols and starch / acrylonitrile hydrolysates can be applied, but acrylic acid is preferred because it has a strong affinity for water, has a high molecular weight, is commercially available, and is easily available. Salt-based and vinyl alcohol-based compounds are preferred. These may be used alone or as a blend of two or more thereof.

The water-absorbent resin is 100 μm or less in a completely dry state,
Preferably an average particle size of 50 μm or less and 20 cc
/ G, preferably a water swelling degree of 100 cc / g or more and hardly soluble in water. If the average particle diameter exceeds 100 μm in a completely dry state, it is not preferable because the spinning stability such as clogging of the nozzle and breakage of the yarn at the time of drawing occurs, and when the water swelling degree is less than 20 cc / g. It tends to be difficult to develop a sufficiently porous structure in the finally obtained fiber.

The water-absorbent resin is added to a thermoplastic polymer melt or solvent solution to form a spinning solution. In the case of the melt spinning method, the water-absorbing resin does not decompose or react at a temperature lower than the spinning solution temperature. In the case of the system, it is preferable that the water absorption performance is not hindered by the spinning method, such as a material that is hardly soluble in the solvent.

The mixing ratio of the water absorbing resin is in the range of 0.5 to 30 parts by weight, preferably 1 to 10 parts by weight based on 100 parts by weight of the thermoplastic polymer. If the amount is less than 0.5 part by weight, the porous structure of the finally obtained fiber becomes insufficient, which is not preferable. On the other hand, if the amount exceeds 30 parts by weight, there is a problem of thread breakage and the like.

The method of blending the water-absorbent resin can be carried out by a conventionally known method, and the method of blending the dispersion of the water-absorbent resin in a viscous liquid or the like is as follows. It is preferable from the viewpoint that aggregation of

[0013] The spinning method of the present invention comprises a known melting, dry,
Wet spinning, semi-dry spinning-wet spinning can be used.For example, a solvent solution of a thermoplastic polymer or a water-absorbent resin is added and mixed at a stage before a melt is spun from a spinning nozzle. After being made into a stock solution, and then spun, heat treatment is performed in the process of forming the fiber to obtain a porous fiber.

In order to obtain the desired porous fiber, it is preferable that the porous fiber has water at least at the stage of heat treatment. From this point, the porous fiber can be efficiently obtained by performing the heat treatment at 100 ° C. or higher after the spinning, the dry densification, and the wet spinning method or the semi-dry semi-wet spinning method.

[0015] Even in the melt spinning method or the dry spinning method, if a predetermined amount of a water-absorbing resin is added, heat treatment is finally performed in the presence of moisture to obtain a desired porous fiber. Can be.

The heat treatment in the present invention includes general dry heat treatment using hot air or the like, wet heat treatment using steam, hot water, or the like.
Alternatively, known methods such as heat treatment and dyeing using a constant temperature bath such as polyethylene glycol and glycerin can be used, and two or more methods can be used in combination. Of these, wet heat treatment is preferable from the viewpoint of developing a porous structure. It is presumed that the porous structure can be obtained by the expansion mechanism of the water-absorbent resin due to water absorption and the gas expansion force of the adsorbed water by heating and vaporizing. For example, in the case of a heat treatment method not in the presence of water, the resin obtained at the time of heat treatment cannot absorb water, so that the finally obtained fiber tends to have difficulty in obtaining a porous structure. The conditions of the wet heat treatment are 105 to 15
When carried out in pressurized steam at 0 ° C., preferably 120 to 130 ° C., porous fibers can be obtained most efficiently.

In the heat treatment, any of a tensioned state and a relaxed state is possible. In the relaxed state, the porous structure of the fiber to be obtained is more likely to be exhibited and the bulkiness tends to be increased. In addition, for the stretching or the like, a method or the like performed in ordinary fiber production can be used.

The heat treatment of the present invention may be performed after crimping, after crimp setting, after cutting, or the like. Further, it may be performed after the product becomes a pile product or a doll hair. Pores are also generated by such heat treatment, but have a porosity of 10 as compared with a sufficiently dense fiber having the same composition and the same fineness.
% Or more is preferable because the volume feeling when made into a pile product is improved. If the porosity exceeds 60%, the texture such as the touch and the strength of the single fiber tend to decrease.

The thermoplastic polymer in the present invention includes acrylonitrile, homopolymers or copolymers such as vinyl chloride and vinylidene chloride, olefin polymers,
In addition, various polymers such as polyamides, polyesters, and polyurethanes can be applied.However, in order to realize various characteristics such as excellent texture, coloring, and heat retention, a polymer containing acrylonitrile or a vinyl-based polymer is used. Is more preferable. These polymers may be used alone or as a blend of two or more. The copolymer containing acrylonitrile preferably contains 25% by weight or more of acrylonitrile from the viewpoint of imparting heat resistance, and more preferably acrylonitrile 35.
-85% by weight, more preferably acrylonitrile 40
６０60% by weight. If the amount of acrylonitrile exceeds 85% by weight, the feeling such as touch is undesirably reduced.

Further, in the present invention, generally used additives such as stabilizers, organic or inorganic pigments and dyes, matting agents, various tactile sensation improvers, flame retardants, brighteners and the like are used. It can be used as long as it does not impair the water-absorbing performance of the water-absorbing resin to be added, and it does not impair the object of the present invention.

Next, the fiber cross-sections that can be used in the present invention include circular, horseshoe-shaped, cocoon-shaped, potato-shaped,
There are no particular restrictions on polygonal shapes such as triangles, squares, flat shapes, and star shapes, and other irregular shapes. For example, when the ratio of the major axis to minor axis of the fiber cross section is in the range of 2: 1 to 10: 1. , Softness, the feeling of thickness is preferably improved, but if it is outside the lower limit of the range, the sense of hardness tends to increase, and if it exceeds the upper limit of the range, the fiber tends to lose its stiffness. is there.

[0022]

The present invention will be described more specifically with reference to the following examples. The effect evaluation method of the present invention is based on a visual and tactile viewpoint, performs a sensory evaluation by five judges using a pile knitted fabric, and obtains a gloss, texture, and animal-like gloss.
A sample having a voluminous feel was evaluated as “good”, a sample with a lower volume was evaluated as “acceptable”, and a sample with a lower volume was evaluated as “impossible”.

The measurement of the water swelling degree, porosity and fineness, and the measurement of the major axis and minor axis described in the text and in the examples were carried out by the following methods. The relative humidity was calculated from the value measured with a dry and wet bulb hygrometer.

(I) Method for calculating the degree of water swelling: 1.0 g of a water-absorbent resin in an absolutely dry state was weighed, and the conductivity was 0.2 m
Distilled water of S / m (25 ° C.) or less was infiltrated in a graduated cylinder, and the volume of the water-absorbent resin after swelling was measured in an atmosphere maintained at 25 ° C., and an average value of 10 measurements was obtained.

(Ii) Method of calculating porosity: Using a scanning electron microscope (Hitachi, Model S-510), a photograph is taken at a constant magnification and a constant distance from above the vertical cross section of the single fiber, and the porosity is determined. The average value of 100 pieces of the total cross-sectional area was calculated. Next, the average value of 100 cross-sectional areas of the non-porous fibers having the same composition and the same fineness as the fibers was obtained by the same method, and the porosity of the porous fibers was calculated by the following equation. . Porosity (%) = (Sa−Sb) / Sa × 100 where Sa: average value of 100 cross-sectional areas of porous fibers Sb: average value of 100 cross-sectional areas of non-porous fibers ( iii) Measurement method of fineness: Using a motorcycle blow type fineness measuring device (Search Control Electric DC-11), an average value of 100 fibers was obtained and converted to decitex.

(Iv) Definition of long axis and short axis Using a scanning electron microscope (Hitachi S-510),
Take a photograph of the single fiber cross section and use the longest axis as the long axis when viewed from the single fiber side direction, and when viewed from the single fiber cross section direction, view from the single fiber side direction with the axis perpendicular to the long axis. The longest axis was taken as the short axis, and the average value of 100 pieces was determined.

Examples 1 to 7, Comparative Example 1 30% by weight of an acrylonitrile polymer obtained by copolymerizing 50% by weight of acrylonitrile, 49% by weight of vinyl chloride, and 1% by weight of sodium styrenesulfonate in acetone. The average particle size in a completely dry state was 10 cc and 150 cc /
g of an acrylate-based water-absorbent resin having a water swelling degree of 0.1 g per 100 parts by weight of an acrylonitrile-based polymer was added and dispersed, and the obtained composition was a circle having a pore diameter of 0.2 mmφ and 100 holes. Using a two-hole spinneret,
Discharged into a 5% by weight acetone aqueous solution, and the winding speed was 4.5.
It was immersed for 20 seconds at m / min. Subsequently, the film was immersed in a hot water bath at 75 ° C. for 30 seconds while being stretched twice, and the obtained washed yarn was sufficiently dried in a flash dryer at 120 ° C., and then subjected to secondary stretching twice at 120 ° C. Then, heat treatment was performed for 2 minutes in a pressurized steam at 120 ° C. while applying a 0.9-fold relaxation, to obtain a porous fiber having a single fineness of 16.7 decitex. A sliver is created using this fiber, and after sliver knitting, a cut length of 20 mm and a basis weight of 1 k are passed through a back coating, shearing and polisher processes.
A pile knitted fabric of g / m 2 was obtained. Table 1 shows the results.

[0028]

[Table 1] (Examples 8 to 13, Comparative Example 2) An acrylonitrile-based polymer obtained by copolymerizing 50% by weight of acrylonitrile, 49% by weight of vinyl chloride, and 1% by weight of sodium styrenesulfonate was contained in acetone at 30% by weight. 3 parts by weight of an acrylate-based water-absorbing resin having an average particle diameter of 10 μm in a completely dry state and a water swelling degree of 150 cc / g were added to 100 parts by weight of an acrylonitrile-based polymer and dispersed. 25% by weight at 25 ° C. using a spinneret having a circular hole having a hole diameter of 0.2 mmφ and 100 holes.
It was discharged into an aqueous acetone solution and immersed at a winding speed of 4.5 m / min for 20 seconds. Subsequently, the film was immersed in a hot water bath at 75 ° C. for 30 seconds while being stretched twice, and the obtained washed yarn was
After thoroughly drying in a flash dryer at 0 ° C.,
The secondary stretching was performed twice at a temperature of ° C. Thereafter, various heat treatments shown in Table 2 were performed to obtain porous fibers having a single fineness of 16.7 dtex. After making sliver using this fiber and sliver knitting, cut back 20mm through back coating, shirring and polisher process,
A pile knitted fabric having a basis weight of 1 kg / square m was obtained. Table 2 shows the results.

[0029]

[Table 2] (Examples 14-18, Comparative Examples 3-4) Acetylonitrile-based polymer obtained by copolymerizing 50% by weight of acrylonitrile, 49% by weight of vinyl chloride, and 1% by weight of sodium styrenesulfonate was contained in acetone at 30% by weight. Things
3 parts by weight of the various water-absorbing resins shown in Table 3 having an average particle diameter of 10 μm in the absolutely dry state were added to 100 parts by weight of the acrylonitrile-based polymer and dispersed. Was discharged into a 25% by weight aqueous solution of acetone at 25 ° C. using a spinneret having various holes of 100 holes as shown in (1) and immersed at a winding speed of 4.5 m / min for 20 seconds. Then 75
Immersion for 30 seconds in a hot water bath at a temperature of 2 ° C. while stretching the film twice, and after thoroughly drying the obtained washed yarn in a flash dryer at 120 ° C., successively performing secondary stretching at 120 ° C. twice.
Heat treatment was performed in pressurized steam at 120 ° C. for 2 minutes while relaxing 0.9 times, to obtain a porous fiber having a single fineness of 16.7 dtex. A sliver is created using this fiber, and after sliver knitting, the cut length is 20 m through the back coating, shearing and polisher processes.
m, a pile knitted fabric having a basis weight of 1 kg / square m. Table 3 shows the results.

[0030]

[Table 3]

[0031]

Industrial Applicability According to the present invention, it is possible to industrially safely produce a porous fiber excellent in bulkiness and suitable for use in clothing or toys.

Claims (10)

[Claims] 1. A method for producing a porous fiber, comprising spinning a thermoplastic polymer to which a resin having a water-absorbing property is added and then performing a heat treatment to develop pores. 2. The method for producing a porous fiber according to claim 1, wherein the spinning of the thermoplastic polymer is a wet spinning, and a wet heat treatment is performed after a dry and dense treatment after the spinning. 3. The method for producing a porous fiber according to claim 1, wherein the spinning of the thermoplastic polymer is dry spinning or melt spinning, and a wet heat treatment is performed after the spinning. 4. The water swelling degree of a resin having a water absorbing property is 10
The method for producing a porous fiber according to claim 1, 2 or 3, which is at least 0 cc / g. 5. The method for producing a porous fiber according to claim 1, wherein the resin having a water absorbing property contains an acrylate compound. 6. The method for producing a porous fiber according to claim 1, wherein the resin having a water absorbing property contains a vinyl alcohol-based compound. 7. The method for producing a porous fiber according to claim 1, wherein the amount of the resin having water absorbing performance is 0.5 to 30 parts by weight based on 100 parts by weight of the thermoplastic polymer. . 8. The method for producing a porous fiber according to claim 1, wherein the thermoplastic polymer is a polymer containing acrylonitrile. 9. The method for producing a porous fiber according to claim 1, wherein the ratio of the major axis to the minor axis of the fiber cross section is in the range of 2: 1 to 10: 1. 10. The method for producing a porous fiber according to claim 1, wherein the porosity of the pores generated by the heat treatment is in the range of 10 to 60%.