JPS59192710A - Water-absorbing composite fibrous material - Google Patents

Abstract

PURPOSE:To provide the titled composite fiber having excellent durability, strength and handleability, by compounding fine particles of a water-absorbing resin to a fiber composed mainly of a fiber-forming polymer and having a specific structure. CONSTITUTION:Fine particles of a water-absorbing resin such as hydrolyzed starch-acrylonitrile copolymer and having an average particle diameter of <=100mu and maximum particle diameter of <=300mu are compounded in a fiber or near the surface of a fiber composed mainly of a fiber-forming polymer such as crystalline polyolefin, etc. and having a microfibrillated or microlamellar structure. The water-absorbing particles are connected to the outer atmosphere through microscopic crazings or pores, and the specific surface area of the composite fiber is >=1m<2>/g.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a fibrous material having a fine fibrillar structure made of a composite of fine water-absorbing resin particles.

<Conventional technology and its problems> In recent years, water-absorbing resins have been developed and used as sanitary and medical materials.

Although it has been applied to food packaging materials, agricultural and horticultural materials, etc., most of this water-absorbing resin is in the form of powder and granules, and it is difficult to use it by itself. On the other hand, the development of water-absorbing materials formed into fibrous materials has progressed, and various fibrous water-absorbing materials have been obtained. It is made by heat-insolubilizing CMC (carboxymethyl cellulose) with a degree of carboxymethylation (substitution degree) of around 06 in the fibrous state, or by crosslinking it with epichlorohydrin, ethylene glycol diglyndyl ether, or the like. Although this fibrous water-absorbing material is easier to handle than powder-like water-absorbing resin,
The problem is that the water absorption capacity is low.

In addition, since the entire fiber is chemically modified, it swells when it absorbs water and does not retain its original shape at all, and its two-dimensional strength is also significantly reduced, making it unsuitable for use as a comb. Rough, urethane.

It is already known that a water-swellable resin sheet can be obtained by kneading a water-absorbing resin with ethylene-vinyl acetate copolymer, butyl rubber, or the like. However, in this case, it was added for the purpose of imparting water absorption and swelling properties to the resin.
The water absorption power of the resin as a whole is low.

On the other hand, a term for compounding fine particles in a fine fibrous material has already been published in Japanese Patent Publication No. 51-30605. In all of these proposals, inorganic fine particles are composited into a fiber-forming polymer.

It was not previously known to combine fine particles of an organic polymer compound into a fiber-forming polymer.

<Object of the Invention> The present invention solves the problems seen in conventional fibrous water absorbing materials. The present invention relates to a fibrous water-absorbing material that shows almost no change in fiber morphology even when water is absorbed, and has excellent durability, strength, and handleability.

<Structure of the invention> The water-absorbing composite fibrous material of the present invention has an average particle diameter of 100 μm.
The water absorption property is as follows: Resin fine particles are mainly composed of fiber-forming polyester and are compounded inside or near the surface of a fibrous material having a fine fibril-like or fine film-like structure. It is characterized in that the resin fine particles are connected to the outside through fine voids or pores, and the total specific surface area is 1 m27 g or more.

Below, eight aspects of the present invention will be explained in more detail.

The water-absorbing resin fine particles used in the present invention include:

Hydrolyzed product of tenbun-polyacrylonitrile copolymer 1 A hydrolyzed salt (for example, alkali metal salt, etc.) of a partially crosslinked tenbun-polyacrylic acid co-graft polymer,
Partially crosslinked reactants such as polyoxyethylene, polyvinyl alcohol, polyacrylamide, polyhinylpyrrolidone, polystyrene sulfonate, hydrolysates of methyl methacrylate-vinyl butyrate copolymers, hydrolysates of acrylonitrile-vinyl acetate copolymers The hydrolyzate of a cellulose-polyacrylonitrile copolymer is a partially cross-linked carboxymethyl cellulose. %, hydrolyzate of starch-polyacrylonitrile copolymer 2, hydrophilic salt of partially cross-linked starch-polyacrylic acid cogshift polymer, etc. are preferred from the viewpoint of high water absorption and water retention capacity. .

The water-absorbing resin fine particles are generally compounded by 01 to 6 times the weight of the fiber-forming polymer, although it also depends on the particle size.

As the fiber-forming polymer that serves as a carrier for the water-absorbing resin fine particles, a polymeric substance that can be dissolved in a non-aqueous organic solvent is used, and specifically, polyethylene, polypropylene, polybutene-1, poly-4-methylhentene-1 are used. , HoIJ acrylonitrile, styrene-acrylonitrile copolymer,
PVC.

Examples include polymers further modified with cellulose acetate and the like. Particularly preferred polymers include crystalline polyolefins, acrylonitrile (co)polymers, and cellulose acetate. In addition to these matrix polymers, fiber-forming properties are insufficient.

Ethylene-vinyl acetate copolymers are useful depending on their purpose, such as their low melting point or hydrophilic properties.

Ethylene-acrylic acid copolymer metal salts and the like may be added.

In the composite fibrous material, in addition to the water-absorbing resin fine particles, inorganic fine powder is used for the purpose of reinforcing the fiber structure, etc., with a weight of 0.1 to 5 times the weight of the fiber-forming polymer, preferably 0 to 2 times. It is better to add weight and co-composite. The primary particle size of the inorganic fine powder is 10 μm or less, preferably 10 μm or less, and is generally preferably smaller than the average particle size of the water-absorbing resin fine particles. Examples of inorganic fine powders include perilla, alumina, carunium carbonate, talc, kaolin, clay, and titanium oxide.

Carbon, iron oxide, etc. are used.

The solvent used when spinning the composite fiber of the present invention is:

The fiber-forming polymer must be stable at elevated temperatures and must be substantially inert to water-absorbing resin fine particles and inorganic fine powder. Solvents suitable for these conditions include pentane and hexane.

Hydrocarbons such as cyclohexane and benzene, logogenated hydrocarbons such as methylene chloride, chloroform, carbon tetrachloride, and trichlorethylene, alcohols such as methyl alcohol, ethyl alcohol, and inopropyl alcohol, nonitrile such as acetonitrile, and acetone. , ethyl methyl!・Glue 17 such as N, ethers such as ethyl ether and tetrahydrofuran, l! ! Examples include esters such as methyl t-acid and ethyl acetate, and mixtures of these solvents. These solvents are appropriately selected depending on the characteristics of the fiber-forming polymer used.

Water absorption (L1 fat particles originally contain a small amount of water and absorb water in the solvent, so they are very likely to aggregate in the spinning solution. Therefore, prevent the water-absorbing resin particles from agglomerating in the spinning solution. At the same time, it is preferable to add a surfactant for the purpose of uniform dispersion.Surfactants include lipophilic or hydrophilic anionic, cationic, amphoteric, and nonionic surfactants, and they are used as appropriate. Ru.

Due to the action of the surfactant, not only the water-absorbing resin fine particles but also the fine particles present in the spinning dope are uniformly dispersed. In this case, the effect is more fully exerted than in the agglomerated state, and it becomes less likely to fall off from the composite fibrous material.

Add ultraviolet absorber to composite fibrous materials as necessary.

Antioxidants, fungicides, and insect repellents may be added.

A fine fibrillated synthetic fiber string-like article having the water-absorbing resin fine particles of the present invention composite therein is produced using the above-mentioned water-absorbing resin fine particles, fiber-forming polymer, and solvent by the following method. A mixture of water-absorbing resin fine particles, a fiber-forming polymer, and a relatively low-boiling-point solvent that is difficult to understand at normal temperature and pressure, but can be dissolved under elevated temperature and pressure, is heated and stirred under closed conditions. , the fiber-forming polymer is dissolved to form a dispersion in which water-absorbing resin fine particles are uniformly dispersed. Additionally, the dispersion is rapidly discharged through a nozzle at high temperature and high pressure into a low pressure region of substantially atmospheric pressure. The solvent in the discharged dispersion liquid momentarily evaporates in a low pressure region, and the fiber-forming polymer solidifies.

Fine fibrillated fibers are formed. Solvents play an important role in providing the desired structure during fiber formation. That is, unless the solvent is selected so that the fiber-forming polymer is substantially dissolved at a temperature above the boiling point of the solvent, it is impossible to produce the fine fibrillated fibrous material of the present invention.

As explained above, the water-absorbing composite fibrous material of the present invention is:
Since the water-absorbing resin fine particles are compounded into the fibers with good dispersibility, even when the fibers are cut or torn, there is little shedding of the fine particles, and they do not substantially flow out. However, because the composite water-absorbing resin fine particles are connected to the outside through fine voids or pores, they exhibit a water absorption rate comparable to that of uncompounded powder. Fine fibrillar fibers containing water-absorbing resin particles.

It is made of a high molecular weight, fiber-forming polymer that does not swell when mixed with water, so it is extremely durable.

Even when water is absorbed, there is no change in the fiber morphology that poses a practical problem, and it is easy to handle.

The present invention will be described in detail below, but these examples are not intended to limit the technical content of the present invention.

Example 1 400 mesh pass water absorbent resin (average particle size 15 μm
, Sunwet E M-ROOO [Starch-Aku IJ 0
Hydrolyzate of 2l-1) copolymer], manufactured by Sanyo Chemical Co., Ltd.)
50 parts by weight, high density polyethylene (Hi-Zex 21
00J, manufactured by Mitsui Petrochemical QflJ) 100 parts by weight surfactant (dotecylamine propionic acid A/salt,
25 parts by weight (manufactured by Sanyo Chemical Co., Ltd.) were placed in an autoclave together with 1300 parts by weight of hexane, and while stirring, the
After heating to 160°C and holding for 10 minutes.

A continuous fibrous material composited with water-absorbing resin fine particles was produced by discharging the dispersion liquid at 150° C. under normal pressure through the nostle (1 mInφ) of an autoclave ff1H1 (7).

The specific surface area of the obtained fibrous material was 4.5 m27 g. Further, as a result of scanning electron microscopy (SEM) observation, it was found that the water-absorbing resin fine particles were connected to the outside world through fine voids or pores.

After immersing the fibrous material in excess water and allowing it to absorb enough water, 9
When the water retention amount of the fibrous material was measured by the so-called centrifugal dehydration method in which it was placed in a bag and centrifugally dehydrated, it was found that the fibrous material was 1 gA7. O
g of water was retained. Also.

The water absorption rate was 90 to 100% of the total amount of water absorbed in about 2 minutes. The shape of the fibrous material after use was almost unchanged from that before use, and no water-absorbing resin particles were observed to fall off.

Example 2 400 mesh pass water absorbent resin (average particle size 15 μm
, Sunwet E M-600. Sanyo Chemical Q3) 50 parts by weight, high density polyethylene 100 parts by weight, silica ()
100 parts by weight of Toku [manufactured by IJ Chida] and a surfactant (dodecylaminopropionic acid A)
1 salt, manufactured by Sanyo Chemical Co., Ltd.) was charged into an autoclave together with 71,400 parts by weight of hexa, and using the same spinning conditions as in Example 1, a continuous fibrous material composited with water-absorbing resin fine particles and silica was produced.

The specific surface area of the obtained fibrous material was 32.1 m27g. Further, as a result of SEM observation, it was found that the water-absorbing resin fine particles were connected to the outside world through fine voids or pores.

: When the water retention amount of this water-absorbing composite fibrous material was measured by the same method as in Example 1, it was found that 1 g of this fibrous material
111 g of water was retained per cup. Moreover, the water absorption rate was 90 to 100% of the total amount of water absorbed in about 2 minutes. When the fibrous material was subjected to water absorption and drying five times, there was almost no decrease in the water retention capacity, and almost no change in the fiber morphology was observed.

Comparative Example 1 When the water absorption capacity was measured in the same manner as in Example 1 using the fibrous water absorption material "Aqualon" (manufactured by Vercules), the water absorption capacity was 50 times the weight of the fiber, but this fiber did not absorb water. Then, it swelled so much that it did not retain its original shape at all. In addition, the fibers upon water absorption are very sticky and have poor handling properties. 1 It is considered difficult to use them alone like ordinary water-absorbing resins.

Comparative Example 2 Cotton is considered as a natural fiber that absorbs water well. When the water retention amount was determined using this cotton in the same manner as in Example 1, it was found that 1 ga of cotton retained 90.5 g of water, which was not too much.

Claims (1)

[Claims] Water-absorbing resin microparticles with an average particle size of 100 μm or less and a maximum particle size of 300 μm or less are compounded inside or near the surface of a fibrous material mainly composed of a fiber-forming polymer and having a fine fibril-like or fine film-like structure, and the water-absorbing A water-absorbing composite fibrous material characterized in that fine resin particles are connected to the outside through fine voids or pores, and the total surface area is 1 m27 g or more.