JPH01260014A - Water-absorbing fiber - Google Patents

Abstract

PURPOSE:To obtain a fiber, excellent in water absorbability, providing neutral pH in absorbing water and suitable for sanitary uses, by forming a mixture of an alkaline metal salt of a specific (meth)acrylic acid based polymer with a polyvalent epoxy compound, etc., into a fibrous shape and heat-treating the resultant fibrous composition. CONSTITUTION:The objective fiber obtained by forming a mixture consisting of (A) an alkaline metal salt of (meth)acrylic acid based polymer having a neutralization degree within the range of 0.2-0.95, preferably 0.4-0.8 and (B) a polyvalent epoxy compound (e.g., glycerol diglycidyl ether or diglycidyl ether of bisphenol A) or polyhydric amine (e.g., ethylenediamine or pentamethylenehexamine) into a fibrous shape and heat-treating the formed fibrous composition, preferably at 100-180 deg.C.

Description

[Detailed description of the invention] [Field of medical application] The present invention has excellent water absorption properties, and has water absorption properties that are suitable for use in sanitary materials, which require that - at the time of water absorption be neutral. Regarding fibers.

[Conventional technology]

In recent years, super absorbent resins that can absorb 10 to 100 times their own weight in vaporized water have been developed and are conveniently used in paper diapers, sanitary products, and other art supplies, but most of the current super absorbent resins is in the form of powder or granules, and is used in combination with pulp, nonwoven fabric, etc., but it has drawbacks such as difficulty in uniform dispersion because of the powder, and a tendency to cause migration in the final product.

[Problem to be solved by the invention]

A fibrous water-absorbing resin is desired as a solution to these drawbacks, but it is inexpensive and has excellent performance. (Required) Most commercially available absorbent fibers are no good at all.

[Means to solve the problem]

According to the present invention, the above problem is solved when the degree of neutralization of the prisoner is 0.2 to 0.
A mixture consisting of an alkali metal salt of an acrylic acid polymer or a methacrylic acid polymer within the range of 95 and (B) a polyhydric 4-oxy compound or a polyhydric amine is formed into a fiber shape, and then heat-treated to form sl. ! This problem can be solved by obtaining a fibrous water-absorbing resin. In other words, an alkali metal salt of an acrylic acid polymer or a methacrylic acid polymer whose degree of neutralization has been adjusted so that the - value when absorbed is neutral is mixed with a polyvalent epoxy compound or a polyvalent amine and formed into a fiber. Afterwards, by heat treatment, the acrylic acid polymer 7'C is combined with the methacrylic acid group in the X base and the epoxy 7' group in the polyvalent epoxy compound! ! Friends are many 1F1fi Ami/Naka no Amino/
+1" group≠4 cross-linking occurs and becomes insoluble in water, resulting in a water-absorbent fiber that is highly water-absorbent and has a neutral - value when water is absorbed.

What is the acrylic acid-based polymer or methacrylic acid-based ) acrylonitrile, poly(meth)
It also includes compounds obtained by hydrolyzing acrylamide and the like. Furthermore, the base I combination may include nests based on vinyl compounds such as styrene, vinyl acetate, and vinyl alcohol. It is also possible to carry out the weighting using a (meth)acrylic late monomer that has been partially neutralized in advance to obtain a partially neutralized alkali metal salt of a (meth)acrylic acid polymer in the second stage.

If the molecular weight of these (meth)acrylic acid-based polymers is too low, it will not be possible to obtain water-absorbing fibers with a large water absorption capacity, while if it is too high, the viscosity of the solution will be high when it is made into an aqueous solution, and the water-absorbing fibers will not be able to be obtained. 10 due to problems with handling during manufacturing.
,000~1000,000. Preferably 50,000
~500,000 is suitable.

The alkali metal salt of an acrylic acid polymer or a methacrylic acid polymer used in the present invention is obtained by partially neutralizing a polymer of acrylic acid or methacrylic acid with an alkali metal compound, and is used as an alkali metal compound. Examples include oxides or hydroxides of alkali metals such as sodium, potassium, and lithium, especially hydroxides)
Potassium hydroxide is preferably used for IJumma.

In the present invention, the reaction ratio of the alkali metal compound to the acrylic acid polymer or the methacrylic acid polymer, that is, the degree of neutralization, is determined as follows: 1 molar equivalent of the alkaline substance reacts with 1 mol of carboxyl group present in the polymer. It is important that the degree of neutralization is within the range of 0.2 to 0.95, assuming that the degree of neutralization is 1. If the degree of neutralization is less than 0.2,
The resultant water-absorbing fibers not only become acidic when water is absorbed, making them unsuitable for thin material applications, but also have poor reactivity with polyvalent epoxy compounds or polyvalent amines, making it impossible to obtain a solid polymer. . On the other hand, if the degree of neutralization exceeds 0.95 t-, the - at the time of water absorption becomes alkaline, which is not preferable. From these points of view, the degree of neutralization of the copolymer is 0.2 to 0.95. It is preferably within the range of 0.4 to 0.8. In addition, "one-neutral" in thin material applications means that when a water-absorbing resin is absorbed with distilled water, it becomes methyl orange (changes color in acidity).
and phenolphthalein (changes color in alkalinity) indicator, which means that it is not colored, not necessarily p) 17
It is not necessary that the pt is within the range of approximately 14.5 to 8.0.

The polyvalent epoxy compound used in the present invention means a compound that can partially crosslink an alkali metal salt of a metacoacrylic acid polymer and has two or more epoxy groups in its molecule. Typical compounds are partially water-soluble, such as glycerin diglycidyl ether, ethylene glycol diglycidyl ether, and ethylene glycol soglycidyl ether.

Examples include di- or triglycidyl ethers of polyhydric alcohols such as glycerin triglycidyl ether, propylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, and trimethylolpropane triglycidyl ether. Mayu, diglycysol etherified compounds containing carxyl groups, cyclohexene oxide, bicyclohebutene oxide,
Also included are polyvalent epoxy compounds containing alicyclic epoxy groups such as cyclopentene oxide. Furthermore, it is also possible to use materials that do not need to be uniformly dissolved in the reaction system but are uniformly dispersed. Examples of such polyvalent epoxy compounds include diglycidyl ether of bisphenol A, dimer acid glycidyl ester type epoxy resin, and metal-containing epoxy resin.

In addition, when caustic alkali is used as the alkaline substance in the present invention, it is necessary to use a chlorohydrin etherified compound, such as glycerin dichlorohydrin/ether, glycerin trichlorohydrin ether, ethylene glycol dichlorohydrin ether, before the epoxy compound. Dorine ether, glopylene glycol sochlorohydrin ether, etc. can also be used.

Among these polyhydric epoxy compounds, diglycidyl ethers of polyhydric alcohols such as glycerin diglycidyl ether, ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, and 7t are polyglycidyl ethers such as polyglycidyl ether and glycol diglycidyl ether. Preferably convenient
Ru. Further, it is important to use one having an epoxy equivalent of 100 to 500.

Next, the polyvalent amine used in the present invention refers to all water-soluble polyvalent amines having two or more amino groups in the molecule, and an example thereof is ethylenediamine.

Diethylenetriamine, triethylenetetramine/.

Examples include tetraethylenepentamine, pentaethylenehexamine, and polyethyleneimine having straight iron-like columns and branches.

It is also possible to use two or more types of these polyvalent epoxy compounds or polyvalent amines in combination.

The ratio of the polyvalent 22x compound or polyvalent amine to the alkali metal salt of the (meth)acrylic acid copolymer is:
It is appropriate that the violet is present in an amount of 0.1 to 5% by weight, preferably 0.3 to 3% by weight, based on the carboxyl group in the polymer. If the amount is too low than this range, the water absorption capacity of the obtained water-absorbing fibers will be high, but the glue strength during water absorption will be weakened, causing problems such as adhesion of fibers to each other and part of the fibers dissolving in water. . Also, if it is larger than this range,
This is a poor choice because the crosslinking density becomes too high and only a product with a low water absorption capacity can be obtained.

Next, a specific method for manufacturing 1 m of water absorbent fibers of the present invention will be described. First, a (meth)acrylic acid polymer and a predetermined amount of an alkali metal compound are reacted in water to prepare an aqueous solution of a partially neutralized alkali metal salt (13) of the polymer. Polyvalent epoxy compound or polyvalent amine (II) ffi is added and the components are mixed and stirred until uniformly dispersed or dissolved to obtain a homogeneous mixed aqueous solution of (I) and (If). Thus obtained 7' If a filament is formed by a method such as spray drying or melt blowing using the mixed aqueous solution of (11 and (II)), or by ordinary wet or dry spinning, a fibrous composition can be obtained. You can get things.

By subjecting this fibrous composition to total heat treatment, the component (1
) and (II) undergo a crosslinking reaction to obtain water-insoluble superabsorbent fibers. If the heat treatment temperature is too low, crosslinking will be slow and the heat treatment time will be too long; if it is too high, the fibers will deteriorate in beak color.
Suitably, the temperature is within the range of 80°C.

The water-absorbing fiber of the present invention obtained by the method described above exhibits a high water-absorbing capacity of 10 to 500 times its own weight, preferably 50 to 300 times its own weight, and the pH at the time of water absorption is neutral ( It can be determined whether or not - when water is absorbed is neutral by mixing a small amount of mine indicator and absorbing chlorine water.] Therefore, it can be used as art materials such as disposable diapers and sanitary products, as a substitute for sphagnum moss, as a water retention material for soil, etc. * Suitable for horticultural uses.

The water-absorbing fiber of the present invention may be made of other polymeric materials, m.
It can be used as a convenience product containing all i-agents, pigments, dyes, ultraviolet absorbers, antioxidants, antifungal agents, bactericides, insecticides, herbicides, fertilizers, fragrances, deodorants, etc. It is also possible to process and use it in the form of strands, yarns, non-woven fabrics, or woven fabrics, depending on the needs.

〔Example〕

EXAMPLES Hereinafter, the present invention will be specifically explained with reference to Examples, but the present invention is not limited thereto in any way.

Example 1 Acrylic acid polymer (molecular weight 250,000.
100 parts by weight, hydroxide) IJium 41,6
Part by weight and 1274 parts by weight of water were all mixed and stirred to prepare a water bath solution of Na salt of acrylic acid polymer (degree of neutralization 0.75, concentration 10
%) were prepared. Then, the above aqueous solution has an epoxy equivalent of 1
0.5 parts by weight of glycerin diglycidyl ether (No. 45) was added to the above copolymer, and the mixture was sufficiently stirred and mixed to obtain a uniform mixed aqueous solution. This mixed aqueous solution was applied to an Anhydro Con-Guktos grade dryer (inlet gas temperature 250°C).

Exit gas temperature 120°C, residence time 20-30 seconds.

Feed IL 15 kg/hr, Mad My Day 3
0.00 Orpm) to obtain a fibrous composition with a diameter of several μm. This fibrous composition was dried in a hot air dryer for 12 hours.
Heat treatment was performed at 0° C. for 1 hour to obtain water absorbent fibers with a water absorption capacity of 220 times.

The liquid properties of the above-mentioned water-absorbing fibers when absorbing water are 7t, as there is no layer color due to phenolphthalein and no discoloration due to methyl orange.

Example 2 100 parts by weight of the acrylic acid polymer used in Example 1, 16.6 parts by weight of IJ (hydroxide) and 855 parts by weight of water were mixed and stirred to form an aqueous solution of Na salt of the acrylic acid polymer (neutralized). degree 0.3, concentration 12%)! Made in i14.

Polyethylene glycol diglycidyl ether t3X Dobe Ouka having an epoxy equivalent of 410 was added to this aqueous solution and thoroughly mixed to obtain a uniform mixed aqueous solution.

This aqueous solution was dried using a spray dryer in the same manner as in Example 1 to obtain a fibrous composition with a diameter of several microns. This fibrous composition was heat-treated at 1140° C. for 30 minutes to obtain water-absorbing fibers with a water absorption capacity of 95 times and neutral inside when water was absorbed.

Comparative Example 1 100 weight parts of the acrylic acid polymer used in Example 1, 5.5 weight parts of sodium hydroxide, and 598 weight* parts were mixed and stirred to form an acrylic acid polymer Na salt water bath solution (degree of neutralization). 0.1
, concentration 15) was prepared. A solution obtained by adding and mixing 0.5 parts by weight of the epoxy compound used in Example 1 to this water bath solution was applied to a spray dryer to obtain a fibrous composition. The fibers obtained by heat-treating this composition at 120°C for 1 hour are extremely slimy due to insufficient crosslinking and a large number of dissolved parts. It exhibited discoloration) and was unsuitable for use as an art material.

Comparison 4/IJ2 Sodium polyacrylate (completely neutralized product, degree of polymerization 2.7
00-7,500. 0.5 parts by weight of the epoxy compound used in Example 1 was added to a solution of 100 parts by weight of Wako Pure Industries (manufactured by Wako Pure Industries, Ltd.) in 900 parts by weight of water and thoroughly mixed to obtain a uniform water bath liquid. . The resulting fibrous composition was heat-treated at 120°C for 1 hour by applying this water bath solution to a spray dryer.As a result, the water absorption capacity of the fibrous composition was 180 times, and it had a firm, sticky shape with little bath decomposition. However, when water is absorbed, - is alkaline (colored with phenolphthalein)
Therefore, it is not suitable for use as a supplementary material.

Example 3 A fibrous composition 2 was obtained using spray drying in the same manner as in Example 1 except that a polyethyleneimine tube having a molecular weight of about 600 was used instead of glycerin diglycidyl ether. This fibrous composition was heat-treated at 160° C. for 2 hours to obtain neutral water-absorbing fibers with a water absorption capacity of 210 times.

〔Effect of the invention〕

According to the present invention, it is possible to obtain a water-absorbing fiber suitable for impact applications, which requires excellent water-absorbing properties and a neutral voice when absorbing water.

Patent applicant RiRashi Co., Ltd.

Claims (1)

[Claims] A mixture consisting of (A) an alkali metal salt of an acrylic acid polymer or a methacrylic acid polymer having a degree of neutralization within the range of 0.2 to 0.95, and (B) a polyvalent epoxy compound or a polyvalent amine. A water-absorbing fiber obtained by forming into a fiber and then heat-treating it.