JPS6253479A - Fiber material having water absorbability imparted thereto - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to fibrous materials with a high degree of water absorption. Examples of the form of the fibrous material include paper, nonwoven fabric, cloth or web, mat, felt, cotton-like material, and the like. Fibers include natural fibers such as pulp, cotton, linen, and wool, synthetic fibers such as polyolefin, nylon, and polyester, and mixtures thereof.

BACKGROUND OF THE INVENTION Water-absorbing fiber materials made by dispersing super-absorbent resin powder onto paper or pulp brocade are used in sanitary materials such as sanitary napkins and paper diapers.

Conventional technology Super-absorbent resins have the property of absorbing water hundreds of times their own weight, and super-absorbent resin powders such as acrylic acid polymers and vinyl acetate-acrylic acid ester copolymer hydrolysates are commercially available. ing.

The structure of the polyacrylic acid-based superabsorbent diencephalon is a partially alkali metal salt of polyacrylic acid with moderate crosslinks that is insoluble and swells in water, and the degree of neutralization is so that the pH of the water gel is in the neutral range. adjusted. A large number of patent applications regarding the mounting method have been published.

The polymer skeleton is constructed by radical polymerization of an aqueous solution of acrylic acid alone or a monomer containing a water-soluble comonomer such as methacrylic acid, maleic acid, or acrylamide. Crosslinking can be introduced by self-crosslinking by polymerization of a highly concentrated aqueous solution, or by crosslinking using polyfunctional monomers such as methylenebisacrylamide or N-methylolacrylamide, which has a functional group that reacts with the functional group of the polymer to form a crosslink. This is carried out by methods such as copolymerization of monomers and addition of a crosslinking agent such as ethylene glycol bisglycidyl ether that is reactive with the carboxyl group of the polymer. By these methods, a suitable amount of crosslinking is introduced during the polymerization reaction or during heating and drying of the polymer, thereby imparting a high degree of water absorption to the polymer. A method of producing a graft polymer by adding starch or polysaccharide in addition to the above-mentioned components is also known.

The pH of the aqueous stock solution to be subjected to polymerization is neutralized to a neutral range with caustic alkali, and the reaction is initiated with a water-soluble radical initiator. The polymerization reaction occurs vigorously and a large amount of polymerization heat is generated.

As a method to control the polymerization reaction and carry it out on an industrial scale,
Reverse-phase suspension polymerization method in which the aqueous stock solution is dispersed in the oil phase (1) Thin layer polymerization method that facilitates the removal of polymerization heat, or a thin layer polymerization method that suppresses the formation of crosslinks during polymerization and is subjected to agitation and fluidization treatment as a high viscosity aqueous solution. A method of reacting with a crosslinking agent during heat drying is known.

As mentioned above, the superabsorbent resin powder is sprinkled on paper or pulp cotton and used as an absorbent material for sanitary napkins and paper diapers. There are also examples of spraying it on absorbent cotton to give it water-absorbing properties, and attempts to spray it on other textile materials.

Problems to be Solved by the Invention There are various examples of increasing the water absorbency of these materials by scattering and incorporating superabsorbent resin powder into fiber materials. It adheres to the skin and gives an unpleasant sensation. These fiber materials are often used as sanitary or medical materials (
Separation of the swollen gel, which has absorbed moisture, blood or fluids, from the fiber substrate must be avoided. for that,
Covering fiber material containing super absorbent resin powder with non-woven fabric,
Measures are taken to prevent the gel from spilling out.

The present inventor first impregnated a paper or cloth-like material with an aqueous stock solution containing an alkali metal acrylic acid salt as the main component and producing a superabsorbent resin through a radical polymerization reaction, heated the impregnated material, and obtained a monomer. By polymerizing the components, paper and cloth-like materials with water absorption properties were invented (Japanese Patent Application No. 59-175).
846).

In products obtained by impregnating and polymerizing fiber materials with an aqueous stock solution that produces polyacrylic acid-based superabsorbent resin, the resin is integrated with the fibers and a high degree of water absorption is imparted. When absorbing water, the water-use gel does not separate from the fibers, and the material behaves as if the fibers themselves had a high degree of water absorption. Observation of the water-absorbed sample under a microscope confirms that the fibers are uniformly coated with the superabsorbent resin.

The water-absorbing fiber material produced in this way has remarkable advantages compared to conventional products that are sprayed with resin powder, but on the other hand, the problem is that when the resin content is high, the fiber material becomes hard when drying, and the resin does not contain the water-absorbing fiber material. There is a tendency for the flexibility of the material to be impaired.

Therefore, if it is possible to impart a high degree of water absorption by increasing the superabsorbent resin content without impairing the flexibility of the fiber material, it would have a great practical effect.

Means to solve the problem The fiber material containing super absorbent resin fine powder is sprinkled with it.
An aqueous stock solution containing a partial alkali metal salt of acrylic acid as a main component and having a pH in the neutral range that produces a superabsorbent resin through a radical polymerization reaction is impregnated, and the impregnated material is heated to remove the monomers contained in the aqueous stock solution. It has been found that the components can be polymerized to provide a highly water-absorbing fibrous material. The amount of superabsorbent resin contained in the fiber material that is the product is expressed as the sum of the amount sprayed in advance as a powder and the amount of resin produced by polymerization of the aqueous stock solution.

The fiber material obtained by the above method not only exhibits a high degree of water absorption corresponding to the resin content, but also the resin powder is strongly bonded to the fibers by the resin produced by polymerization and is integrated, so that when water is absorbed, the fiber material absorbs water. The Japanese gel is prevented from detaching from the fibers. Furthermore, the amount of resin produced to coat the fibers is at a level that does not impair the flexibility of the fiber material, and can bond the resin powder to the fiber substrate sufficiently firmly.

As a result, the fiber material of the present invention can be obtained which solves the above-mentioned problems, has a high degree of water absorption, does not detach the water gel when water is absorbed, and does not lose its flexibility.

The fibers applied to the present invention are not particularly limited in terms of material,
Although various fibers such as those mentioned above can be used, cellulose fibers are particularly suitable. The form of the fiber material is also as described above (various forms are selected depending on the application).

The particle size of the super absorbent resin fine powder sprinkled in advance is 10
It is preferably 0 mesh or less, and a powder of 200 mesh or less is also suitably used. The undesirable fine powder of 200 mm or less, which is produced as a by-product when a super absorbent resin is pulverized to produce a powder product, is also suitable for the product of the present invention.

An aqueous stock solution containing a partial alkali metal salt of acrylic acid as a main component and producing a superabsorbent resin through a radical polymerization reaction is prepared according to a known method. The outline is as described above, but a preferred example is as follows.

An aqueous stock solution is prepared by adding a radical initiator and a crosslinking agent component to a neutral aqueous solution having a concentration of 20 to 40% by weight, which is obtained by adding caustic soda to an acrylic acid aqueous solution to neutralize 70 to 80 moles of carboxyl groups. As the radical initiator, a persulfate salt such as persulfurized potassium is usually used. As means for introducing crosslinking, there are various methods as mentioned above, including the addition of a polyfunctional comonomer such as methylbisacrylamide, or the radical crosslinking method invented by the present inventor (Japanese Patent Application No. 6O-136).
653) is appropriate.

The amount of superabsorbent resin fine powder sprinkled on the working fiber material, the aqueous stock solution and the amount of polyacrylic acid-based superabsorbent resin produced therefrom are adjusted depending on the water absorbency required for the product.

If the amount of resin produced from the aqueous stock solution is a large number (x amount) relative to the fiber material, it will be effective in fixing the dispersed resin powder to the fibers. On the other hand, the upper limit of the amount of resin varies depending on the product and application, and is generally less than half the amount of resin per 4-fiber material.

The water-absorbing RA fiber material of the present invention can be used as a water-absorbing material by itself, but when it is in the form of a web, mat, or cotton, the fibers can be spread and mixed with #R fibers that do not contain resin. You can also do it. For example, when producing water-absorbent treated absorbent cotton, absorbent cotton sprinkled with superabsorbent resin powder is impregnated with an aqueous stock solution, the dried product obtained by polymerization is opened, and then mixed uniformly with untreated absorbent cotton. After that, it can be processed into products such as rolled cotton, chikara, and tofu. Products obtained from blended cotton not only have an excellent dry and absorbent feel and are highly absorbent, but also have a hydrated gel of 4#1. There is no possibility of detachment from the fiber.

Water absorbency #1 of the present invention. A wide variety of textile products are developed by mixing, combining, and laminating different fibers.

Example 1 To an aqueous solution of 34 parts of caustic soda (purity 93'1) dissolved in 230 parts of water, 72 parts of acrylic acid, 0.16 parts of methylenebisacrylamide and 0.2 parts of potassium persulfate were added to adjust the pH. An aqueous stock solution of 6.8 was prepared.

The polyacrylic acid-based super water absorbent resin fine powder that has passed through a 160-meter mesh was uniformly dispersed on a matte pulp cotton using 100 f/8 tons of pulp cotton, and the above aqueous stock solution was added to the pulp cotton at a rate of 32 f per 100 m/s of pulp cotton. Spray to uniformly impregnate. This aqueous stock solution impregnated product was heated at a temperature of 95°C in a nitrogen atmosphere for 30 minutes.
Polymerized for minutes.

From the weight of the dry product, 16 per 100P of pulp cotton
Contains t super absorbent resin. Of these, 8f is due to polymerization of the aqueous stock solution.

One sample was put into water, and 20 minutes later, it was taken out of the water and the weight of the absorbed water was measured, and it was 45 f.

The water absorption rate of the sprayed resin was determined to be 280 times its own weight, and the water absorption rate of the pulp cotton itself was determined to be 11 times its own weight. Therefore, the water absorption rate of the resin produced from the aqueous stock solution is calculated to be 240 times its own weight.

The product has approximately 4 times the water absorption capacity compared to untreated valve cotton, and the water absorbent material does not exhibit the detachment of hydrated gel seen in samples sprayed with resin, and also provides a soft feel. .

Example 2゜The super absorbent resin powder of Example 1 was applied to a pulp-based nonwoven fabric and a polyester-based nonwoven fabric at a rate of 6 per 100P of nonwoven fabric.
? It was distributed at a ratio of These were uniformly impregnated with the aqueous stock solution of Example 1 at a rate of 4 Ct per 100 f of nonwoven fabric. Next, the impregnated sample was subjected to polymerization treatment in the same manner as in Example 1.

The dried product is 100% raw material nonwoven fabric. Contains binder resin powder 6f and polymerized resin 109 from an aqueous stock solution.

The weight of the water absorbent of each sample 1f is as follows: 43f of pulp-based nonwoven fabric;
It was polyester nonwoven fabric 32f.

In addition, the water-absorbed sample showed no detachment of the water-use gel and had a good feel.

Example 3 72 parts of acrylic acid, 34 parts of caustic soda (purity 93%),
Methylenebisacrylamide 0.05 part, persulfate power IJ
An aqueous stock solution was prepared from 1 part O, and 115 parts water.

Absorbent cotton is fluidized and dispersed in the air, and per 1001 absorbent cotton,
Super absorbent resin fine powder 10 of Example 1? Spread evenly,
Further, the above stock solution 201 was uniformly sprayed to impregnate. The impregnated material was compressed and polymerized at a temperature of 95° C. for 30 minutes in a nitrogen atmosphere.

The dried product is 10 resin powder per 100 P of absorbent cotton.
? and polymerized resin 32 from an aqueous stock solution. The weight of the water absorbed material of this sample 1f was 4817. Also absorbent cotton 1
The weight of the water absorption material f is 122.

The product was then dry-opened and simultaneously mixed with untreated absorbent cotton to obtain a homogeneous mixture consisting of 1 part of product and 2 parts of absorbent cotton. The weight of the water absorbed from 1f of this product is 24f, which is about twice the water absorbency of untreated absorbent cotton. The water-absorbing material does not show any detachment of the hydrated gel, and its feel is almost the same as that of regular absorbent cotton.

Effects of the Invention As shown in the examples, the water-absorbing fiber material of the present invention does not exhibit separation of the water gel from the base material, which is seen in conventional resin powder spraying products, and has high water absorption and a good feel. have

Water-absorbing fiber materials can take various forms, and a wide variety of water-absorbing material products can be developed by mixing or combining them with other types of water-absorbing materials.

Claims (2)

[Claims] (1) A fiber material containing fine powder of a super absorbent resin is impregnated with an aqueous stock solution containing a partial alkali metal salt of acrylic acid as a main component and having a pH in the neutral range that produces a super absorbent resin through a radical polymerization reaction. A fibrous material imparted with water absorbency, which is produced by heating the impregnated material and polymerizing the monomer components contained in the aqueous stock solution. (2) The fibrous material imparted with water absorption properties according to claim 1, wherein the fibrous material containing the super-absorbent resin fine powder is a cellulose-based fiber material on which the super-absorbent resin fine powder is dispersed.