JP2006063219A - Water-absorbing resin composite material assembly, method for producing the same, water-absorbing resin sheet and water-absorbing article - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a water-absorbing resin composite material assembly in which water-absorbing resin particles are uniformly fixed to fibers throughout before and after water absorption, which has high shape retention stability as a sheet irrespective of before and after water absorption and in which a water-absorbing resin composite material is readily recovered and reused by opening or sieving and a water-absorbing resin, and to provide a water-absorbing resin sheet. <P>SOLUTION: The water-absorbing resin composite material assembly is obtained by collecting a plurality of water-absorbing resin composite materials each having one water-absorbing resin particle and one or more fibers bonded to and/or embedded in the water-absorbing resin particle. The weight of the fibers embedded in the water-absorbing resin particle contained in the water-absorbing resin composite material assembly is the weight of the fibers bonded to the water-absorbing resin particle or above and the water-absorbing resin composite material assembly is opened or sieved. The water-absorbing resin composite material assembly 500 is produced by supplying liquid drops 200 of a liquid containing a polymerizable monomer before polymerization and/or during polymerization and fibers 300 in counter-current directions, contacting them, advancing polymerization of the polymerizable monomer and depositing the polymer. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an aggregate of water-absorbent resin composites in which water-absorbent resin particles are fixed to fibers and a method for producing the same, and in particular, used in the fields of water-absorbing materials used in various sanitary materials, agriculture and civil engineering. The present invention relates to a water-absorbent resin composite assembly that can be effectively applied to a water retention agent and the like and capable of forming a thin and flexible water-absorbent resin sheet, and a method for producing the same. The present invention also relates to a water absorbent resin sheet using the water absorbent resin composite aggregate, and a water absorbent article including the water absorbent resin sheet.

  In the present invention, “water absorption” includes not only water but also absorption of liquids other than water.

  Composites of water-absorbent resin and fibers in which powder or particulate water-absorbent resin is fixed to the fiber are various sanitary materials such as sanitary napkins and disposable diapers, various agricultural materials, various industrial materials, etc. Has been used. Various attempts have been made with respect to the technology for fixing the water-absorbent resin to the fibers, and various problems have been pointed out with respect to these technologies.

  For example, when a water-absorbent resin is used as a powder, it is pointed out that the handling is complicated, the process is difficult to disperse uniformly, and the like. For example, for the purpose of thinning a portion (absorbent body) responsible for water absorption performance such as sanitary materials, the amount of fibers such as pulp in the absorber is relatively decreased with respect to the amount of the water absorbent resin. When the water-absorbing resin is partially localized or easily dropped, problems such as a decrease in water-absorbing performance, deterioration of wearing feeling, and the influence of the dropped water-absorbing resin on the human body may occur.

  In order to solve these problems, a method for fixing a water-absorbent resin and fibers using polymerization has been studied. For example, according to WO 03/057764, as a method for producing a highly water-absorbent resin with good shape retention stability, a water-soluble adhesive dissolved in water or alcohol is used together with the highly water-absorbent resin powder in the antigravity direction. A method is disclosed in which a composite is produced by spraying and adding pulp or silica from the top. The composite of the water-absorbent resin and fiber produced by this method has no problem in the shape retention stability of the water-absorbent resin, but when it is used as an absorbent material for sanitary materials, etc. In addition, the water-absorbent resin that contains water from the pulp, silica, etc. is removed to dissolve the water-soluble adhesive and ooze out on the surface of the water-absorbent body to show stickiness or to fix the water-absorbent resin by the movement of the user When the body fluid enters the water absorbent body again, the body fluid leaks out from the water absorbent body without being absorbed by the water absorbent resin. Have the problem of feeling uncomfortable.

In order to solve these problems, a method for producing a water-absorbing material in which a substantially spherical water-absorbing resin is discontinuously fixed on the surface of a non-molded fiber has been proposed (Japanese Patent Laid-Open No. 11-93073). The water-absorbing material produced by this method certainly solves the above problem, but the non-molded fibers and the droplets in the course of polymerization are falling in the direction of gravity (the same (cocurrent) direction). Therefore, the frequency of contact between the droplets in the polymerization and the non-molded fibers is low, and it is difficult to form a composite of the droplets and the non-molded fibers in the gas phase. Therefore, the water-absorbing material produced by this method is in contact with the receiving surface at the bottom of the polymerization tank where fibers or polymerization particles are deposited, so that the non-molded fibers form a three-dimensional network between the polymerization particles. The formed nonwoven fabric is formed. Therefore, although the water absorbing material obtained by this method is excellent in shape retention stability before and after water absorption, the water absorbing material is opened, and the composite of the water absorbing resin and the fiber is individually separated. It cannot be recovered in a state. For this reason, expensive composites of water-absorbent resin and non-moldable fibers cannot be collected and recycled from broken materials, dirt, non-standard products, used water-absorbing articles, etc. in the manufacturing process. There was a problem that it took. That is, for example, as a technique related to a method for recovering a powdered water absorbent resin, a technique for recovering a water absorbent resin powder by sieving hygiene products after sieving under forced vibration is disclosed (Japanese Patent Laid-Open No. 2003-2003). However, it is difficult to apply such a recovery method.
WO 03/057764 Publication Japanese Patent Laid-Open No. 11-93073 JP 2003-39023 A

  The object of the present invention is that the water-absorbent resin particles are uniformly fixed to the fiber through before and after water absorption, so that the shape retention stability as a sheet is high regardless of before and after water absorption, and the breakage in the manufacturing process is also achieved. Water-absorbent resin sheet that can easily recover and reuse water-absorbent resin composites by opening or sieving used water-absorbent resin sheets. Is to provide a water-absorbent resin composite aggregate, a method for producing the same, and a water-absorbent resin sheet using the same. Another object of the present invention is to provide water-absorbing articles such as sanitary materials, industrial materials, and agricultural materials using such water-absorbing resin sheets.

  As a result of intensive studies, the present inventors have found that non-molded fibers and polymerization droplets as used in the prior art are not dropped together in the direction of gravity and contacted in parallel, but non-molded fibers and By increasing the contact frequency and the collision energy at the time of contact by bringing droplets in the middle of polymerization into contact in the countercurrent direction, more non-molded fibers can be embedded, opened, and sieved. The present inventors have found that an aggregate can be produced efficiently and completed the present invention.

That is, the gist of the present invention is as follows.
(1) A water-absorbent resin composite comprising a polymerizable monomer that forms a water-absorbent resin by polymerization and fibers, wherein one or more of the fibers are bonded and / or embedded in one water-absorbent resin particle. Is a method for producing an aggregate formed by collecting a plurality of liquid droplets containing the polymerizable monomer before and / or during polymerization in the gas phase and the fibers. A vapor phase polymerization step of allowing polymerization of the polymerizable monomer to proceed after feeding in a direction and a deposition step of depositing the fiber resin composite obtained in the vapor phase polymerization step, The manufacturing method of the water-absorbent-resin composite aggregate which performs.
(2) In (1), in the gas phase polymerization step, 10 to 2000 parts by weight of the droplets are supplied to 100 parts by weight of the fiber, and the method for producing a water absorbent resin composite aggregate .
(3) In (1) or (2), recovering the fiber that has not been bonded or embedded in the water-absorbent resin particles from the deposit obtained in the deposition step and supplying the recovered fiber to the gas phase polymerization step A method for producing an aggregate of water-absorbent resin composites.
(4) A water absorbent resin composite comprising a plurality of water absorbent resin composites each having one water absorbent resin particle and one or more fibers bonded and / or embedded in the water absorbent resin particle. The weight of the fibers embedded in the water absorbent resin particles contained in the water absorbent resin composite aggregate is not less than the weight of the fibers adhered to the water absorbent resin particles, and the aggregate Is an aggregate of water-absorbent resin composites that can be opened or sieved.
(5) The number of fibers embedded in the water-absorbent resin particles out of the total number of fibers adhered and / or embedded in the water-absorbent resin particles contained in the water-absorbent resin composite aggregate in (4) Is a water-absorbent resin composite aggregate characterized by being 50% or more.
(6) A water absorbent resin composite characterized in that it is a water absorbent resin composite aggregate produced by the method according to any one of (1) to (3) in (4) or (5). Body assembly.
(7) A water absorbent resin sheet obtained by molding the water absorbent resin composite aggregate according to any one of (4) to (6) into a sheet shape.
(8) In (7), the water absorbent resin composite aggregate, the fibers not bonded and / or embedded in the water absorbent resin particles, and the water absorbent resin particles in which the fibers are not bonded and / or embedded. A water-absorbent resin sheet obtained by molding one or both of them into a sheet shape.
(9) The water absorbent resin sheet according to (8), wherein the content of the water absorbent resin composite aggregate is 50% by weight or more.
(10) A water absorbent article comprising the water absorbent resin sheet according to any one of (7) to (9).

  According to the method for producing a water-absorbent resin composite aggregate of the present invention, in a gas phase, liquid droplets and fibers containing a polymerizable monomer before polymerization and / or polymerization in progress are directed in the countercurrent direction. Since the polymerization of the polymerizable monomer proceeds by feeding and contacting, the frequency of contact between the droplets during polymerization and the fiber is high, and the collision energy at the time of contact is high. The body can be easily formed. For this reason, as in the conventional method of dropping fibers and droplets in the same direction, the problem of forming a three-dimensional network of the aforementioned resin and fibers due to contact between the droplets and fibers during the deposition after deposition is The water-absorbent resin composite comprising one water-absorbent resin particle and one or more fibers bonded and / or embedded in the water-absorbent resin particle is not included in the fibers contained in the water-absorbent resin composite. A water absorbent resin composite aggregate that is an aggregate formed by entanglement and that can easily obtain individual water absorbent resin composites by opening or sieving can be produced.

  In the water absorbent resin composite according to the present invention, the water absorbent resin particles are uniformly fixed to the fibers, and even if the water absorbent resin particles absorb water and become a gel state, they are uniformly fixed to the fibers in this way. The state that is being maintained can be maintained.

  The water-absorbent resin sheet of the present invention has such a water-absorbent resin composite that has a uniform sheet shape in which a plurality of water-absorbent resin composites are connected to each other by entanglement of fibers contained in the water-absorbent resin composite. It is excellent in shape retention stability before and after water absorption. Therefore, the water-absorbent resin composite does not move and localize in the sheet due to vibration during conveyance or handling, nor does it move in the sheet when it becomes a gel after water absorption. Moreover, since this water-absorbent resin composite is simply joined by the entanglement of the fibers, it can be easily opened and sieved and separated. , Non-standard products and returns from the market, and collection and reuse from used water-absorbent resin sheets are also easy.

  Further, in the water absorbent resin composite aggregate of the present invention, the water absorbent resin can be present in a high ratio to the fiber, the water absorbency is remarkably high, and even if it is ultra-thin, it is flexible and long. A sheet having high form stability can be formed over a period.

  That is, the water-absorbent resin composite constituting the aggregate of water-absorbent resin composites of the present invention is one in which water-absorbent resin particles are uniformly fixed to fibers adhered and / or embedded therein, A water-absorbent resin using a large amount of fibers embedded in water-absorbent resin composite particles, effective for shape retention stability after water absorption, and using such a water-absorbent resin composite aggregate of the present invention Compared to the conventional sheet, the water-absorbent resin is uniformly fixed even when the weight ratio of the water-absorbent resin / fiber is large. In addition, a water-absorbing resin sheet having excellent absorption performance can be realized. In addition, it has excellent shape retention after water absorption and resin fixability, and also has good liquid permeability. Therefore, when used in sanitary materials, it also has the feature that no body fluid leaks. Moreover, since the water-absorbent resin composite aggregate of the present invention can be easily opened or sieved to separate the water-absorbent resin composite, the present invention is formed by molding it into a sheet. The water-absorbent resin sheet is economical because it can easily recover and reuse the water-absorbent resin composite from broken materials, dirt, non-standard products and returned goods from the market, and used products. It is.

  The water absorbent article of the present invention using the sheet of the present invention exhibiting such excellent performance is industrially used as a sanitary material, industrial material, agricultural material, etc., especially in the field of sanitary materials such as paper diapers and sanitary napkins. Very useful.

  Hereinafter, the present invention will be described in detail with reference to preferred embodiments of the present invention. In the present specification, a numerical range represented by using “to” means a range including numerical values described before and after “to” as a lower limit value and an upper limit value.

[1] Water-absorbent resin composite aggregate The water-absorbent resin composite aggregate of the present invention comprises one water-absorbent resin particle and one or more fibers bonded and / or embedded in the water-absorbent resin particle. An aggregate of water-absorbent resin composites, wherein the weight of the fibers embedded in the water-absorbent resin particles contained in the water-absorbent resin composite aggregate is equal to or greater than the weight of the fibers adhered to the water-absorbent resin particles. And can be opened or sieved.

  First, the water absorbent resin composite constituting the water absorbent resin composite aggregate of the present invention will be described with reference to FIG. FIG. 1 is a schematic explanatory view showing an embodiment of a water absorbent resin composite according to the present invention.

(1) Form of water absorbent resin composite The water absorbent resin composite according to the present invention comprises one water absorbent resin particle and one or more fibers bonded and / or embedded in the water absorbent resin particle (this The term “fiber” refers to “non-molded fiber” described later). The water absorbent resin particles are preferably substantially spherical. In the present invention, the fiber adhering to the water absorbent resin particles means that “a part is adhered to the surface of the water absorbent resin particles and a part is not adhered to the surface of the water absorbent resin particles. In the following, this fiber may be referred to as “surface adhesive fiber”. Further, the fibers embedded in the water absorbent resin particles are "fibers partially embedded in the water absorbent resin particles and partly exposed from the water absorbent resin particles", In this case, this fiber is sometimes referred to as “partially embedded fiber”.

  In the water absorbent resin composite according to the present invention, a water absorbent resin composite having only one or more surface adhesive fibers 2A as shown in FIG. Hereinafter, it may be referred to as “adhesive complex”.) As shown in FIG. 1B, 3A and a water absorbent resin complex having only one or more partially embedded fibers 2B (hereinafter “embedded complex”). 3B, and a water-absorbent resin composite (hereinafter referred to as “adhesive / adhesive”) having 3B and one or more surface adhesive fibers 2A and one or more partially embedded fibers 2B as shown in FIG. Sometimes referred to as “embedded complex.”) 3C.

  Among these, in the adhesive complex 3 </ b> A, the water absorbent resin particles 1 swell and absorb water, whereby the fibers 2 </ b> A are detached from the water absorbent resin particles 1. In this adhesive composite 3A, since the fibers 2A are fixed to the water absorbent resin particles 1 until the water absorbent resin particles 1 absorb water, the movement of the adhesive composite 3A is suppressed and used for water absorbent articles and the like. When used, it works to increase the shape retention before water absorption. Therefore, in the water-absorbent article, it is possible to prevent the occurrence of a part where the complex does not exist due to the movement of the water-absorbent resin composite, thereby preventing leakage of body fluids and the like, An effect of preventing the water-absorbent resin composite from falling off is obtained.

  Further, since the embedded composite 3B has the fibers 2B embedded in the water absorbent resin particles 1, the fibers 2B are detached from the water absorbent resin particles 1 even if the water absorbent resin particles 1 absorb and swell. There is no. In this embedded composite 3B, the fibers 2B are embedded in the water-absorbent resin particles 1 even after the water-absorbent resin particles 1 have absorbed water, and thus the movement of the embedded composite 3B is suppressed even after water-absorbing swelling. And when used for a water-absorbing article or the like, it has a function of improving shape retention after water absorption. For this reason, when used as a sanitary material, even if the user puts out body fluid and changes the body position, the embedding composite 3B that has absorbed and swollen with water exhibits high shape retention stability without moving again. Even when the body fluid penetrates into the absorbent article, there is an effect that the body fluid can be sufficiently absorbed without leaking the body fluid. Of course, as in the case of the adhesive complex 3A, high shape retention stability is exhibited even before water absorption.

  If it is 3C of adhesion | attachment and embedding composites, it has both the effect of the said adhesive complex 3A, and the effect of the said embedding composite 3B.

  As described above, each of the composites 3A to 3C has an important function in terms of shape retention. Further, as described later, the functions of assisting diffusion of body fluid into the absorbent article and water absorption It also has the function of suppressing resin gel blocking.

(2) Ratio of water-absorbent resin particles and fibers The ratio of the water-absorbent resin to the fibers in the water-absorbent resin composite according to the present invention is described in the section for producing the water-absorbent resin composite aggregate of the present invention described later. Thus, 10 to 1000 parts by weight of the water-absorbent resin is preferable with respect to 100 parts by weight of the fiber by dry weight, and more preferably 50 to 800 parts by weight.

(3) Ratio of surface-bonded fibers and partially-embedded fibers When comparing an adhesive complex and an embedded complex (including an adhesive / embedded complex), an embedded complex (including an adhesive / embedded complex) ) Has shape retention stability after water absorption, the water absorbent resin composite aggregate has a higher ratio of the embedded composite (including the adhesive / embedded composite) in the absorbent article. The shape-retaining stability tends to be good.

  That is, it is preferable that the weight of the partially embedded fiber in the water absorbent resin composite aggregate is larger than the weight of the surface adhesive fiber, and usually the surface adhesive fiber / partial embedded fiber = 40/60 to 0/100 (weight ratio). In particular, it is preferably 30/70 to 0/100.

  The number of fibers is also the total number of fibers adhered and / or embedded in the water-absorbent resin particles contained in the water-absorbent resin composite aggregate, that is, the total number of surface adhesive fibers and partially embedded fibers. Of these, the number of partially embedded fibers is preferably 50% or more, and usually, surface-bonded fibers / partially embedded fibers = 50/50 to 0/100 (lines), more preferably 40/60 to 0/100, particularly preferably 30/70 to 0/100.

(4) Water-absorbent resin particles The water-absorbent resin particles play a role of absorbing water, such as water, urine, and blood, in accordance with the intended use in the water-absorbent resin composite according to the present invention. The water absorption capacity of the water absorbent resin is preferably 5 to 50 g (water absorption amount per 1 g of the water absorbent resin), more preferably 10 to 50 g, and particularly preferably 20 to 50 g.

  The water absorbent resin particles constituting the water absorbent resin composite according to the present invention are preferably substantially spherical particles. Here, “substantially spherical” has a shape of a true sphere and an ellipsoid as a whole, and may have fine irregularities (that is, wrinkles, protrusions, depressions, etc.) on the surface. Further, there may be voids such as pores and cracks on the surface and inside.

  The average particle diameter of the water absorbent resin particles is preferably 10 to 2,000 μm, more preferably 20 to 1,000 μm, and particularly preferably 30 to 500 μm.

  The conventional pulverized water-absorbent resin powder has an irregular and sharp cut surface, so the skin is greatly irritated and the sharp cut surface is lost when mechanical force is applied. There is a disadvantage that fine grains are formed. However, the substantially spherical water-absorbing resin particles do not have such a drawback.

  The water-absorbing resin according to the present invention can be produced by the method described later using the following polymerizable monomer and initiator, and, if necessary, a crosslinking agent.

-Polymerizable monomer which produces | generates a water absorbing resin by superposition | polymerization The polymerizable monomer to be used does not ask | require the kind as long as it provides a water absorbing resin. It is particularly preferable to use a polymerizable monomer whose polymerization is initiated by a redox initiator. This monomer is usually preferably water-soluble.

  A typical example of such a monomer and preferred for use in the present invention is an aliphatic unsaturated carboxylic acid or a salt thereof. Specific examples include unsaturated monocarboxylic acids or salts thereof such as acrylic acid or salts thereof, methacrylic acid or salts thereof; or unsaturated dicarboxylic acids or salts thereof such as maleic acid or salts thereof, itaconic acid or salts thereof, etc. These may be used alone or in admixture of two or more. Among these, acrylic acid or a salt thereof and methacrylic acid or a salt thereof are preferable, and acrylic acid or a salt thereof is particularly preferable.

  As the polymerizable monomer used in the present invention, an aliphatic unsaturated carboxylic acid or a salt thereof is preferable as described above. As an aqueous solution of the polymerizable monomer, an aqueous solution mainly containing an aliphatic unsaturated carboxylic acid or a salt thereof is used. preferable. Here, “mainly comprising an aliphatic unsaturated carboxylic acid or salt thereof” means that the aliphatic unsaturated carboxylic acid or salt thereof is 50 mol% or more, preferably 80 mol%, based on the total amount of the polymerizable monomer. % Or more is included.

  As the salt of the aliphatic unsaturated carboxylic acid, a water-soluble salt such as an alkali metal salt, an alkaline earth metal salt, or an ammonium salt is usually used. The degree of neutralization is appropriately determined according to the purpose, but in the case of acrylic acid, 20 to 90 mol% of the carboxyl group is preferably neutralized with an alkali metal salt or ammonium salt. When the degree of partial neutralization of the acrylic acid monomer is less than 20 mol%, the water absorption ability of the water absorbent resin to be produced tends to be remarkably lowered.

  For neutralization of the acrylic acid monomer, alkali metal hydroxides, bicarbonates, or ammonium hydroxides can be used, but preferred are alkali metal hydroxides. Sodium oxide and potassium hydroxide are mentioned.

  In the present invention, in addition to the above polymerizable monomers such as aliphatic unsaturated carboxylic acids, polymerizable monomers copolymerizable therewith, for example, (meth) acrylamide, (poly) ethylene glycol (meth) acrylate , 2-hydroxyethyl (meth) acrylate, or a low water-soluble monomer, but also alkyl acrylates such as methyl acrylate and ethyl acrylate are in the range where the performance of the produced water-absorbing resin is not deteriorated. It can be copolymerized in an amount. In the present specification, the term “(meth) acryl” means both “acryl” and “methacryl”. The same applies to “(meth) acrylate”.

  Of these polymerizable monomers, those that give a water-absorbing resin are not used as auxiliary components for the aliphatic unsaturated carboxylic acid or a salt thereof, but the main monomer of “an aqueous solution of a polymerizable monomer that gives a water-absorbing resin”. It can also be used as

  The concentration of the polymerizable monomer in the polymerizable monomer aqueous solution containing the above-mentioned aliphatic unsaturated carboxylic acid or a salt thereof as a main component is 20% by weight or more, preferably 25% by weight or more. When this concentration is less than 20% by weight, the water absorption ability of the water absorbent resin after polymerization tends to be insufficient. The upper limit is preferably about 80% by weight from the handling of the polymerization reaction solution.

・ Crosslinking agent Aliphatic unsaturated carboxylic acid or its salt, especially acrylic acid or its salt, may form a self-crosslinking water-absorbing resin by itself, but it also forms a cross-linked structure in combination with a cross-linking agent. It can also be made. When a crosslinking agent is used in combination, the water absorption performance of the produced water absorbent resin is generally improved.

  Examples of the crosslinking agent include divinyl compounds copolymerizable with the polymerizable monomer, such as N, N′-methylenebis (meth) acrylamide, (poly) ethylene glycol (meth) acrylates, and carboxylic acids. Water-soluble compounds having two or more functional groups capable of reacting with polyglycidyl ether such as ethylene glycol diglycidyl ether and polyethylene glycol diglycidyl ether are preferably used. Of these, N, N'-methylenebis (meth) acrylamide is particularly preferred. The amount of the crosslinking agent used is usually 0.001 to 1% by weight, preferably 0.01 to 0.5% by weight, based on the charged amount of the polymerizable monomer.

-Polymerization initiator As a polymerization initiator, what is used by aqueous solution radical polymerization can be used. Examples of such initiators include inorganic and organic peroxides such as persulfates such as ammonium and alkali metals, particularly potassium, hydrogen peroxide, t-butyl peroxide, and acetyl peroxide.

  Furthermore, initiators known as azo compounds can also be used. For example, 2,2'-azobis (2-amidinopropane) dihydrochloride which shows water solubility to some extent can be mentioned.

  Polymerization is initiated by decomposition of the radical polymerization initiator. A commonly known technique is pyrolysis. Often, a polymerization initiator that is not heated is added to the monomer of the reaction solution that has been heated to the decomposition temperature of the polymerization initiator in advance to start the polymerization. This case also belongs to the category of thermal decomposition.

  The initiator preferably used in the present invention is a combination of an oxidizing agent and a reducing agent that forms a water-soluble redox system to some extent.

  Examples of the oxidizing agent include hydrogen peroxide, persulfates such as ammonium persulfate and potassium persulfate, t-butyl hydroperoxide, cumene hydroperoxide, ceric salt, permanganate, chlorite. And hypochlorite. Among these, hydrogen peroxide is particularly preferable. The amount of these oxidizing agents used is 0.01 to 10% by weight, preferably 0.1 to 2% by weight, based on the polymerizable monomer.

  The reducing agent is capable of forming a redox system with the oxidizing agent, specifically, sulfites such as sodium sulfite and sodium bisulfite, sodium thiosulfate, cobalt acetate, copper sulfate, ferrous sulfate, L- Examples include ascorbic acid or L-ascorbic acid alkali metal salt. Among these, L-ascorbic acid or L-ascorbic acid alkali metal salt is particularly preferable. The amount of these reducing agents to be used is usually 0.001 to 10% by weight, preferably 0.01 to 2% by weight, based on the polymerizable monomer.

(5) Fiber (non-molded fiber)
The water absorbent resin composite aggregate of the present invention can be opened and sieved as described later, and each of the water absorbent resin composites exists independently. Therefore, in this invention, it is one of the characteristics to use a non-molded fiber as a fiber of a water absorbing resin composite. This “non-molded fiber” means a fiber that has not yet been formed into a predetermined shape, and is a pad, web, or woven fabric as described in the above-mentioned publications. It is clearly distinguished from a molded fiber having a specific shape, such as a non-woven fabric. Specifically, a fiber lump in which fibers are gathered at random, a fiber lump unraveled by a defibrating machine such as a card machine, and individual fibers are included. Further, the fiber material in a state before the web forming operation is performed is also included in the non-molded fiber according to the present invention. The non-molded fibers are preferably in a state where the fibers are not bundled and each one of the fibers is separated from each other, but not all the fibers need to be separated from each other, If it is in a defibrated state, the effect of the present invention is sufficiently exhibited. If the non-shaped fiber is a fiber mass that its bulk density, from the viewpoint of performing uniform deposition of later droplets, 100~100,000g / ^{m 3,} in particular 500~50,000g / ^{m 3} Is preferred.

  As described above, the surface adhesive fibers and the partially embedded fibers included in the water absorbent resin composite according to the present invention play a role of securing the water absorbent resin particles. This fiber improves the fixability of the water-absorbent resin particles before and after water absorption. That is, since the fibers extending or extending from the surface of the water absorbent resin particles are entangled with each other and stabilized, the rotational motion and translational motion of the water absorbent resin particles during pressing and vibration are prevented. In particular, the partially embedded fiber does not detach from the water-absorbent resin particles even after water absorption, and thus can play an important role in the fixability of the water-absorbent resin particles after water absorption.

  Among the fibers contained in the water-absorbent resin composite according to the present invention, when the partially embedded fibers are composed of hydrophilic fibers, the fibers exhibit an effect of increasing the water conductivity of the water-absorbent resin particles. That is, water can be directly introduced into the water absorbent resin particles through the fibers. In order to exhibit this function more effectively, it is preferable to select and use fibers having high water conductivity described later.

  The surface-bonding fibers have a function of creating a gap between the water-absorbent resin composites and securing a water flow path. For this purpose, it may be preferable to use a fiber having a certain rigidity. The surface adhesive fiber also has an effect of preventing a blocking phenomenon that the composites come into contact with each other due to swelling of the water-absorbent resin and obstruct the flow path of water. On the other hand, when the surface-bonding fiber is a hydrophobic fiber, the fiber exhibits a function of improving water diffusibility between the composites.

  The shape of the fiber used for the water-absorbent resin composite according to the present invention may be hollow or side-by-side to improve liquid diffusibility and water conductivity.

  As the fiber material, synthetic fiber, natural fiber, semi-synthetic fiber, inorganic fiber, or the like can be used.

  The fiber to be used is selected according to the intended use of the water absorbent resin composite and the role of each fiber constituting the water absorbent resin composite. For example, when the composite is used for water-absorbing articles such as sanitary materials, industrial materials, and agricultural materials, fibers having high hydrophilicity such as pulp, rayon, cotton, regenerated cellulose and other cellulose fibers. Is preferably selected. Further, a fiber having high hydrophilicity is preferable from the viewpoint of water conductivity. In particular, groundwood pulp as mechanical pulp; semi-chemical pulp, chemical ground pulp, etc. as chemical mechanical pulp; sulfite pulp, sulfate pulp, soda pulp, nitric acid method pulp, chlorine method pulp, etc. as chemical pulp; Preferred is a mechanically crushed or pulverized product of paper made by recycling, or recycled waste paper pulp that is a mechanically crushed or pulverized product of waste paper. Pulp is preferred for hygiene material applications because of its good feel.

  It is preferable from the standpoint of fixability of the water-absorbent resin particles that each fiber is firmly bonded to the water-absorbent resin particles before and after water absorption. In general, it is known that adhesion between materials having high affinity is strong. From the viewpoint of securing the adhesive strength, it is also preferable in the present invention to use fibers having high affinity with the water-absorbent resin. A fiber having a high affinity with a water-absorbing resin that is generally hydrophilic is a hydrophilic fiber. The affinity between the hydrophilic water-absorbent resin and the fibers used can be regarded as a quantitative measure based on the contact angle of water on the surface of the fiber material. That is, the smaller the contact angle on the surface of the water fiber material, the higher the affinity between the water-absorbing resin and the fiber, and the greater the adhesive strength. Conversely, a large contact angle of water means low affinity and low adhesion. In this sense, the contact angle of water on the surface of the fiber material is preferably 60 ° or less, more preferably 50 ° or less, and most preferably 40 ° or less. The contact angle depends on the shape of the fiber material to be measured and the smoothness of the surface. The contact angle in the present invention means a contact angle with respect to distilled water when the fiber material is placed on a smooth surface such as a film or sheet, and can be measured using an apparatus described later.

  The surface of the hydrophobic fiber may be made hydrophilic so that the contact angle on the surface of the fiber material is 60 ° or less. Therefore, it can be modified with one or more known anionic, cationic or nonionic surfactants. For example, it can be hydrophilized by a method of directly spraying and applying to hydrophobic fibers, a method of applying during or after the formation of fibers or nonwoven fabrics, a method of adding fibers to a polymer composition before spinning.

  On the other hand, in combination with hydrophilic fibers, hydrophobic fibers can also be used from the viewpoint of water permeability and water diffusibility. For example, a hydrophilic fiber can be selected as the partially embedded fiber, and a hydrophobic fiber can be selected as the surface adhesive fiber. If such an aspect is employ | adopted, a hydrophobic fiber will exhibit the function to improve the diffusibility of the water between water absorbing resin particles. In this case, as the hydrophobic fiber, for example, polyester, polyethylene, polypropylene, polystyrene, polyamide, polyvinyl alcohol, polyvinyl chloride, polyvinylidene chloride, polyacrylonitrile, polyurea, Polyurethane, polyfluoroethylene, and polycyanidene vinylidene fibers can be used. Furthermore, in view of environmental problems, synthetic fibers such as biodegradable polylactic acid fibers and aliphatic polyesters may be used instead of synthetic fibers that are not biodegradable.

  From the viewpoint of preventing blocking, it is also important to select a fiber in consideration of the rigidity and fiber diameter of the fiber described later.

  Preferred fibers for use in the present invention are those having an average fiber length of 50 to 50,000 μm. The average fiber length is more preferably 100 to 30,000 μm, still more preferably 500 to 10,000 μm. If the fiber length is longer than 50,000 μm, the fibers adhere to a plurality of water-absorbent resin particles, and the independence of each composite cannot be ensured, and the opening of the aggregate containing this composite tends to be difficult. is there. On the contrary, if the fiber length is smaller than 50 μm, embedding and adhesion to the water-absorbent resin particles are difficult, and there is a tendency that it is difficult to form a sheet by entanglement of fibers.

  Further, in order to obtain the effect of the present invention, it is preferable to select a fiber length that allows the fiber portions extending outward from the surface of the water-absorbent resin particles to be entangled with each other to form a sheet, and the average particle diameter of the water-absorbent resin particles: The ratio of the fiber length is preferably 2: 1 to 1: 1,000. This ratio is more preferably 1: 1 to 1: 500, particularly preferably 1: 2 to 1: 100.

  The fiber preferably has a fiber diameter (fineness) of 0.1 to 500 dtex, more preferably 0.1 to 100 dtex, still more preferably 1 to 50 dtex, and particularly preferably 1 to 1 dtex. 10 dtex. When the fiber diameter is larger than 500 dtex, not only is the rigidity of the fiber too large, it becomes difficult to embed and adhere to the water-absorbent resin particles, but compression molding becomes difficult, and sheeting and thinning due to fiber entanglement become difficult. It may not be preferable. In addition, it may be stiff or crisp and unpleasant for the use such as sanitary products. On the other hand, if the fiber diameter is less than 0.1 dtex, the above-described water conductivity and diffusibility may not be ensured because the fibers are too thin. Moreover, since rigidity is insufficient, there are cases in which it is not possible to prevent such a situation.

  Moreover, fibers can be easily entangled by using non-linear fibers such as a crimped shape, a coiled shape, a branched shape, and a twisted shape as the fiber shape.

  From the above viewpoints, the fiber type, fiber length, fiber diameter, and fiber shape are appropriately selected.

  In addition, it is preferable that the fibers are dispersed as evenly as possible. In general, fibers tend to form a fiber mass due to entanglement, but the apparent fiber mass diameter is preferably 20 mm or less, more preferably 10 mm or less, and most preferably 5 mm or less. Of course, it is needless to say that it is preferable to be independent for each single fiber.

  In order to disperse the fiber mass uniformly, a technique called opening is used as a method of loosening. “Opening” includes the concept of both defibration and fiberization. Defibration includes tearing a sheet-like material such as nylon into strips or fibers. In addition, the fiberization includes cutting the base paper-like cellulose into pulp.

  As a specific method, “Fiber Handbook (Processing)” (Fiber Society of Japan, Maruzen, 1969), page 18 and below, cotton spinning type, eyelash type, woolen type, hemp type, silk spinning type or A rotary blade crusher, a hammer crusher, a pulp defibrator or the like can be used as appropriate. It is also possible to charge the fibers known as flocking and effectively disperse the fibers one by one using the electrostatic repulsion between the fibers and uniformly disperse them.

[2] Method for Producing Water-Absorbent Resin Composite Assembly Next, a method for producing the water-absorbent resin composite assembly of the present invention will be described. There is no particular limitation on the method for producing the water absorbent resin composite aggregate of the present invention, but preferably, in the gas phase, liquid droplets containing a polymerizable monomer before and / or during polymerization are polymerized. After the fiber is supplied and brought into contact with the fiber in the counterflow direction, the polymerization of the polymerizable monomer further proceeds and is deposited according to the method for producing a water absorbent resin composite aggregate of the present invention.

(1) Liquid substance containing polymerizable monomer before polymerization and / or in progress of polymerization In the present invention, “liquid substance” means a liquid substance at 20 ° C. The liquid material preferably has a viscosity at 20 ° C. of 10,000 mPa · s or less. If the viscosity is higher than this, it may be difficult to adhere the liquid to non-molded fibers, and the resulting composite may be non-uniform. The more preferable viscosity of the liquid at 20 ° C. is 0.2 to 2000 mPa · s, and more preferably 0.3 to 1000 mPa · s. Such viscosity is measured by a B-type viscometer (manufactured by Tokimec Co., Ltd.).

  This liquid substance comprises a polymerizable monomer capable of giving the above-mentioned water-absorbing resin and / or a polymerized product thereof.

  In the present invention, the “polymerization progress product” refers to a product in which the polymerization reaction of the polymerizable monomer has partially progressed, and includes the time immediately after the start of polymerization. The degree of polymerization of the polymerizable monomer in the polymerized product is preferably 90% or less, more preferably 60% or less, and particularly preferably 40% or less in terms of monomer polymerization rate. When the polymerization rate in the polymerization progress product exceeds 90%, the liquid droplet containing the polymerizable monomer and / or the polymerization progress product is adhered to the fiber, but the fiber is difficult to be embedded in the droplet. Therefore, the proportion of the above-mentioned partially embedded fibers tends to decrease, and the stability of the water-absorbent resin after water content tends to deteriorate. Here, the monomer polymerization rate is defined as a percentage of [amount of monomer consumed for polymerization / amount of monomer at the start of polymerization].

  As the polymerization progress product, a polymerized monomer previously polymerized to a predetermined polymerization rate may be used, or it is included in the droplet when the droplet is brought into contact with the fiber as in the examples described later. The polymerizable monomer may be used as a state in which polymerization is in progress. Further, a polymerizable monomer and a polymerized product may be mixed and used.

  The details of the polymerization method for making the polymerizable monomer into a polymerization progress product are the same as those described later for the method of polymerizing droplets in contact with the fibers.

  The liquid material according to the present invention is suitably used in the state of a solution obtained by dissolving the polymerizable monomer and / or the polymerized product thereof in a solvent. Although it does not specifically limit as this solvent, For example, water, methanol, ethanol, acetone, a dimethylformamide, a dimethylsulfoxide etc., and these mixtures can be used. The solvent preferably used is water from the viewpoint of cost and the like.

  When the solvent is used, the total concentration of the polymerizable monomer and the polymerized product is not particularly limited, but is preferably 10% by weight or more, more preferably 20% by weight or more. If this concentration is less than 10% by weight, the polymerization rate is slow, and the yield and economy may be inferior. The upper limit of this concentration is preferably the concentration in the saturation solubility of the polymerizable monomer and / or the polymerized product in the solvent. When the concentration exceeds the saturation solubility, solid content is precipitated in the liquid material, and the liquid material containing the polymerizable monomer and / or the polymerized product may be uniformly attached to the fiber in the form of droplets. It can be difficult.

  When both the polymerizable monomer and the polymerized product are contained in the liquid material, the blending ratio of the two is appropriately set according to the purpose. In this case, the polymerizable monomer that is a constituent unit of the polymerization progress product may be the same as or different from the polymerizable monomer contained in the liquid material.

  A reaction initiator for the polymerization reaction, a catalyst, or the like can be added to the liquid material. Moreover, the additive which adds the function as mentioned later can also be added to this liquid substance in the range which does not impair the characteristic of a polymerization reaction or the water-absorbing resin obtained.

(2) Method of supplying liquid substance The liquid substance is ejected from a nozzle and polymerized in a gas phase. As the nozzle used here, a known nozzle can be used as long as it can spray droplets during polymerization. For example, the nozzle currently disclosed by Unexamined-Japanese-Patent No. 2003-40904 can be used. Using such a nozzle, two liquids each containing a polymerizable monomer and a polymerization initiator in at least one of the first liquid and the second liquid are sprayed and mixed in the gas phase. In this case, the liquid containing the polymerizable monomer needs to prevent polymerization from proceeding before mixing the two liquids. For example, when a redox polymerization initiator composed of an oxidizing agent and a reducing agent is used as the polymerization initiator, the first liquid can contain an oxidizing agent and the second liquid can contain a reducing agent. At this time, the polymerizable monomer can be contained in one or both of the first liquid and the second liquid. Alternatively, the first liquid may contain a polymerizable monomer, and the second liquid may be prepared by mixing an oxidizing agent and a reducing agent immediately before use.

  Moreover, it is preferable that at least one of the first liquid and the second liquid is ejected into the gas phase so that the ejection cross section becomes a liquid film having a closed curve shape to generate droplets. In the case of the nozzle disclosed in the above Japanese Patent Application Laid-Open No. 2003-40904, the spray droplets from the nozzle rise or fall while opening in a holocone shape (trumpet shape).

  As soon as both the first liquid and the second liquid ejected by the nozzle are mixed, the polymerization starts, and the polymerization progresses in the droplets and rises or falls in the polymerization chamber. The atmosphere in the polymerization chamber can be arbitrarily set as long as the polymerization reaction is not hindered. Usually, nitrogen, helium, carbon dioxide, or the like is used as the atmospheric gas, but air or water vapor can also be used. When water vapor is fed into the atmosphere, moisture evaporation from the polymerizable monomer-containing liquid material is based on the concentration of the polymerizable monomer-containing liquid material used for the reaction and the moisture content required for the water-absorbent resin particles to be produced. What is necessary is just to set from a viewpoint of how much it is made. The temperature of the atmosphere is usually room temperature to 150 ° C, preferably room temperature to 100 ° C.

(3) Fiber conveying method As a method for supplying fibers (in a state where the fibers are opened, not in the fiber mass) in order to make contact with the droplets during polymerization, a generally known conveying method can be used. Spatial density of the fibers in the polymerization vessel will be described later, preferably in the range of 10~1,000g / ^{m 3} when partially causing embedding the fibers into the water-absorbent resin, further a range of 25~750g / ^{m 3} is preferably In particular, a range of 50 to 500 g / m ³ is preferable. If this upper limit is exceeded, fibers that are not embedded in the water-absorbent resin composite are produced, and if the lower limit is not reached, a water-absorbent resin that does not embed fibers is produced, and the yield of the water-absorbent resin composite is relatively reduced. Problems arise. In order to supply the fibers as finely and uniformly as possible, it is preferable to supply the fibers as a mixed phase flow with gas. As the gas used here, those mentioned above as the gas phase gas that gives the reaction field can be used. Among these, air is preferable from the viewpoint of economics and reduction of environmental load.

  The weight mixing ratio of fibers and gas supplied as a multiphase flow is preferably 1:20 or less, and the linear velocity of the gas is preferably in the range of 0.1 to 20 m / sec. If the linear velocity of the gas exceeds 20 m / sec, the locus of the reaction mixture during polymerization in the reaction field may be disturbed, and adhesion to the inner surface of the polymerization tank may become a problem. On the other hand, if it is less than 0.1 m / second, the fiber uniformity may not be ensured.

  The temperature of the gas supplied as a multiphase flow is desirably selected within a range that does not significantly inhibit the polymerization. In this sense, it is specifically 20 ° C. to 150 ° C., preferably 20 ° C. to 100 ° C. From the viewpoint of fiber conveyance, the humidity in the gas is preferably low. However, if the humidity is excessively low, the humidity in the polymerization tank is lowered, and the water in the aqueous monomer solution evaporates before the polymerization proceeds. As a result, the polymerization rate may be remarkably reduced, or the polymerization may be stopped in the middle.

(4) Contacting method between droplets and fibers In order to uniformly attach the liquid droplets to the non-molded fibers, the liquid and non-molded fibers are simultaneously oriented as in the examples described later. It is effective to attach the droplets to the non-molded fibers while supplying them in the flow direction. Moreover, it is desirable to supply the liquid and the non-molded fibers in a certain amount. Even if the supply method is a pulsating flow, the effect of the present invention can be obtained, but the obtained composite distribution may be easily biased.

  In addition, it is preferable that the droplet diameter (average particle diameter) of the droplet during polymerization at the time of contacting with the non-molded fiber is 50 to 3,000 μm, more preferably 50 to 2,000 μm, particularly 50 to 1,000 μm. It is preferable. If the particle size of the droplet is less than 50 μm, it may be difficult to adhere the droplet to the fiber. If the particle size exceeds 3,000 μm, the droplet will not be uniformly adhered to the fiber, or the droplet is spherical. May not be retained, and may become a water scrap.

  When the liquid is formed into droplets with a nozzle, a known atomization technique can be used as a method for adjusting the droplet diameter. For example, droplet formation using a rotating disk atomizer, ultrasonic method, and the like can be mentioned, but the invention is not limited to these.

  The amount of the liquid attached to the fiber is preferably 10 to 2000 parts by weight, more preferably 50 to 1500 parts by weight with respect to 100 parts by weight of the fiber.

  In addition, the amount of the water-absorbent resin in the obtained water-absorbent resin composite is preferably 10 to 1000 parts by weight, more preferably 50 to 800 parts by weight with respect to 100 parts by weight of the dry weight. If the amount of the water-absorbent resin is less than 10 parts by weight with respect to 100 parts by weight of the fiber, it is difficult to obtain the merit of the composite, and if it exceeds 1000 parts by weight, the immobilization of the water-absorbent resin may tend to be uneven. In addition, the water-absorbing resin may be easily detached from the fiber.

  In the present invention, the phrase “supplying and contacting the liquid droplets and fibers in the countercurrent direction” means that the liquid supply direction (for example, the ejection direction from the nozzle) and the fiber supply direction. The angle formed by is greater than 90 °, and this angle is preferably 120 ° or more, more preferably 150 ° or more and 180 ° or less.

(5) Water-absorbent resin composite aggregate and fiber recovery method The water-absorbent resin composite formed by the contact between the droplets and the fibers during polymerization falls, for example, from a polymerization composite tank as described later. . Therefore, it is efficient to collect this fallen object on an endless track such as a belt conveyor. In order to increase the recovery rate, the recovery surface side of the belt conveyor may be decompressed to form a descending airflow.

  Further, the water absorbent resin composite aggregate collected in this manner contains fibers that are not bonded or embedded in the water absorbent resin particles. It is preferable to collect fibers that are not bonded or embedded in the water-absorbent resin particles and reuse them as fiber raw materials. In this case, the recovery of the fiber from the deposit can be performed using, for example, an air classifier as shown in Examples described later. Further, as will be described later, the fibers can be circulated to the contact step with the droplets before being deposited.

(6) Specific Production Example Next, a specific production example of the water absorbent resin composite aggregate of the present invention will be shown with reference to FIG. FIG. 2 is a schematic explanatory view showing an embodiment of a method for producing a water-absorbent resin composite aggregate according to the present invention. Polymerization of a polymerizable monomer using a double-cylindrical polymerization composite tank 100 and water absorption 1 shows a method for producing a water-absorbent resin composite aggregate of the present invention by combining a resin and a fiber.

  The polymerization composite tank 100 has a double cylindrical structure in which an outer cylinder 101 and an inner cylinder 102 are concentrically arranged, and a liquid material containing a polymerizable monomer is provided below the inner cylinder 102. A monomer spray nozzle 103 for ejecting the liquid droplets is provided, and liquid supply pipes 104A and 104B for supplying the first liquid and the second liquid for droplet polymerization described above are connected to the nozzle 103. In addition, an air supply pipe 106 and an air curtain forming means (not shown) for supplying steam-containing air to the outer peripheral portion of the nozzle 103 to form the steam air curtain 105 are provided. On the other hand, a fiber (non-molded fiber) supply port 107 is provided in the upper part of the polymerization composite tank 100. A belt conveyor 108 is provided below the polymerization composite tank 100.

  In this method, a liquid material containing a polymerizable monomer is ejected from the nozzle 103 to generate a droplet 200 in the middle of polymerization as described above, and the droplet 200 in the middle of polymerization is raised in the inner cylinder 102. The superposed droplet 200 that has risen in the inner cylinder 102 falls across the gap between the inner cylinder 102 and the outer cylinder 101 after passing over the peripheral wall end of the inner cylinder 102 in a parabolic manner. When this droplet 200 exceeds the upper end of the peripheral wall of the inner cylinder 102, the fiber 300 falling from the fiber supply port 107 and the droplet 200 come into contact in the countercurrent direction (angle of about 180 °). The fibers 300 that have come into contact with the droplets 200 during polymerization form a composite 400 with the droplets, fall between the inner cylinder 102 and the outer cylinder 101, and accumulate on the lower belt conveyor 108. The droplet 200 rises in the inner cylinder 102 and then drops between the inner cylinder 102 and the outer cylinder 101 and accumulates on the belt conveyor 108 to complete the polymerization. The body collection 500 is recovered.

  The vapor air curtain 105 has a gas blowing nozzle around the nozzle 103 as necessary so that the droplet 200 does not adhere to the inner wall of the inner cylinder 102 when the droplet 200 rises in the inner cylinder 102. Installed and formed. The air curtain 105 needs to be set to a temperature that can maintain the optimum temperature in the polymerization tank. Further, the air curtain 105 needs to be adjusted to have such a strength that the superposed droplet 200 that has moved up the inner cylinder 2 can smoothly exceed the upper end of the peripheral wall of the inner cylinder 102. Conditions under which the polymerization droplet 200 jumps over the upper end of the peripheral wall of the inner cylinder 102 are controlled by the discharge speed of the liquid material containing the polymerizable monomer in the nozzle 103, the air curtain conveyance speed, the fiber supply air speed, and the like. In addition, in order for the fiber 300 to be embedded in the polymerization droplet 200, the monomer polymerization rate of the polymerization droplet 200 when the fiber 300 contacts the droplet 200 is greatly related. That is, when the monomer polymerization rate is low, the ratio of partially embedded fibers in the supplied fibers increases (conversely the ratio of surface adhesive fibers decreases), and the embedded depth also increases. Conversely, when the monomer polymerization rate is high, the proportion of partially embedded fibers decreases (in contrast, the proportion of surface adhesive fibers increases), and the embedded depth becomes shallow. The energy at which the fiber 300 and the droplet 200 during polymerization collide countercurrently and the monomer polymerization rate are importantly related to the ratio of partially embedded fibers in the resulting water absorbent resin composite aggregate. It is important to select appropriately.

  Further, in this method, by providing a gap between the monomer spray nozzle 103 and the inner cylinder 102, it is possible to generate a reflux of the airflow between the inner cylinder 102 and the outer cylinder 101. Then, using this reflux air flow, the non-contact non-molded fiber is recovered in the inner cylinder 102 by utilizing the low bulk specific gravity of the non-contact non-mold fiber, and is raised together with the droplet 200 to be reused. It doesn't matter. Moreover, as long as it does not disturb the burying of the non-molded fiber, a substance to which various functions described later may be added to the polymerization composite tank 100 together with the non-molded fiber as necessary.

[3] Characteristics of water absorbent resin composite aggregate (1) Opening and sieving of water absorbent resin composite aggregate The water absorbent resin composite aggregate produced as described above is a water absorbent resin composite. Are collected as an aggregate which is entangled with each other due to the entanglement of the fibers. Since the water-absorbent resin composite in this aggregate exists independently, it can be opened easily. For the opening, the opening method described in the description of the fiber, for example, cotton spinning type, lash type, spinning type, hemp spinning type, silk spinning type, or rotary feather type pulverizer, hammer type pulverizer, pulp defibrator, etc. Can be used as appropriate. In particular, it is preferable to open the water-absorbent resin composite aggregate using a spreader having many pins and blades. Furthermore, an apparatus and conditions that do not damage the water-absorbent resin particles due to mechanical impact are preferable. A known spreader can be used for the spread. For example, as shown in Fig. 5 (a) described later, a method using a fiber opening machine that rotates cylinders with needle-like pins in the same direction and winds and opens them between the cylinders; A method of applying a large centrifugal acceleration and applying an impact force due to a collision with the housing to open the fiber (Japanese Patent Laid-Open No. 5-9813, Japanese Patent Laid-Open No. 6-57542); a cylinder having a needle-like pin and a needle-like pin And a method of mechanically opening the absorbent sheet while suppressing fiber cutting using an auxiliary plate having

  Defective products, fouled products, and used water-absorbent resin sheets that are generated when a water-absorbent resin sheet described later is created can be similarly opened.

(2) Sieving of water-absorbing resin composite After opening the water-absorbing resin composite aggregate, the water-absorbing resin composite can be sieved. When sieving, an apparatus and conditions that do not damage the water-absorbent resin particles are preferable. For example, giving one or both of known forced agitation and forced vibration operation, for example, as shown in FIG. 5B described later, sieving by performing a decompression operation such as suction from the opposite side of the mesh be able to. Of course, sieving may be performed simultaneously with the opening.

(3) Liquid permeability of water-absorbent resin composite aggregates Generally, high water-absorbent resins are used for sanitary materials, etc., but by absorbing bodily fluids, they become swollen and soft, and the particle spacing becomes narrower. Gel blocking occurs in which gels come into contact with each other and suppress diffusion of body fluids. In the water-absorbent resin composite according to the present invention, the fibers are adhered and / or embedded in the water-absorbent resin particles, thereby functioning to suppress gel block of the water-absorbent resin after water absorption and swelling. However, when the fibers are bonded to the water-absorbent resin, the fibers and the water-absorbent resin are not firmly fixed due to water absorption from the surface, and the fibers come off and agglomerate due to mechanical force. Since the surface of the water-absorbent resin without fibers causes gel block, the diffusion of body fluid is worsened. When the fiber is embedded in the water-absorbent resin, blocking does not occur because the fiber and the water-absorbent resin are stable without being weakened even if water is absorbed from the surface.

  Therefore, in the present invention, in the water absorbent resin composite swollen with artificial urine, the concept of “liquid permeability” is used to evaluate whether the artificial urine freely flows through the gaps of the water absorbent resin composite.

  Although the detailed evaluation method will be described in the following test examples, in consideration of the usability and efficiency of the sanitary material, the liquid-absorbing resin composite constituting the water-absorbing resin composite aggregate has a liquid flow rate of 200 to 500 ml / It is preferable that it is second, in particular 250 to 500 ml / second, especially 300 to 500 ml / second. When this liquid passing speed is lower than 200 ml / second, the absorption of body fluid is delayed, so that a person using it as a sanitary material feels uncomfortable. Conversely, if it is faster than 500 ml / second, it may leak from the sanitary material without being absorbed.

[4] Water-absorbent resin sheet Next, the water-absorbent resin sheet of the present invention will be described.
(1) Structure of water-absorbent resin sheet The water-absorbent resin sheet of the present invention adheres to the water-absorbent resin particles described later together with the water-absorbent resin composite aggregate of the present invention or the water-absorbent resin composite aggregate of the present invention. And / or fibers that are not embedded (hereinafter may be referred to as “free fibers”) and water absorbent resin particles that are not bonded and / or embedded with fibers (hereinafter referred to as “powder water absorbent resin”). One or both of them may be formed into a sheet shape. Preferably, the content of the water absorbent resin composite aggregate of the present invention in the water absorbent resin sheet is 50% by weight or more, The amount is preferably 60% by weight or more, and particularly preferably comprises only the water absorbent resin composite aggregate of the present invention.

  When the water absorbent resin sheet of the present invention includes free fibers, the dry weight ratio of the free fibers and the water absorbent resin composite is preferably 90:10 to 0: 100, and 80:20 to 0: 100. Is more preferable, and it is still more preferable that it is 50: 50-0: 100. If the dry weight ratio of the free fiber and the water-absorbent resin composite exceeds 90:10, and there are many free fibers, the effect of the water-absorbent resin becomes substantially difficult to be exhibited, and the bulk density becomes small and bulky. There is a case.

  Moreover, when the water absorbent resin sheet of this invention contains powder water absorbent resin, it is preferable to add so that the dropout rate of a water absorbent resin may be 5% or less in evaluation mentioned later.

-Free fiber Free fiber is a fiber that is neither embedded nor bonded to water-absorbent resin particles. If necessary, non-molded fibers may be mixed in the sheet so that free fibers exist. The presence of this free fiber can further improve flexibility, soft feeling, water conductivity, water permeability, water diffusibility, air permeability and the like. Moreover, the fiber opening property and sieving property of the sheet itself can be improved by appropriately selecting the fibers to be added.

  The preferred free fibers are those having an average fiber length of 50 to 100,000 μm. More preferably, it is 100-50,000 micrometers, More preferably, it is 500-20,000 micrometers. If the average fiber length is longer than 100,000 μm, it may be difficult to open the water absorbent resin sheet. On the contrary, when the average fiber length is less than 50 μm, the mobility of the fiber itself is large, and thus there is a problem that the fiber leaks from the water absorbent resin sheet. The free fiber also preferably has an average fiber diameter of 0.1 to 500 dtex, more preferably 0.1 to 100 dtex, even more preferably 1 to 50 dtex, and particularly preferably 1 to 10 dtex. It is. When the average fiber diameter is larger than 500 dtex, not only is the rigidity of the fiber too large and mixing with the water-absorbent resin composite becomes difficult, but compression molding becomes difficult, which may not be preferable for thinning. In addition, the use of sanitary products may be stiff or tingling, and the touch may not be preferable. Conversely, if the average fiber diameter is less than 0.1 dtex, the above-described water conductivity and diffusibility may not be ensured because the fibers are too thin. Moreover, since rigidity is insufficient, blocking may not be prevented.

  In addition, as a fiber kind of free fiber, the same thing as the above-mentioned surface adhesive fiber and / or partial embedding fiber can be employ | adopted according to the addition purpose.

  From the above viewpoints, the fiber type, fiber length, and fiber diameter are appropriately selected.

-Powder water-absorbing resin As the powder water-absorbing resin, commercially available resins can be used. For example, sodium polyacrylate, potassium polyacrylate, acrylic acid-vinyl alcohol copolymer, crosslinked sodium polyacrylate, starch-acrylic acid graft polymer, isobutylene-maleic anhydride copolymer or saponified product thereof, etc. One or more of the powders are used. The water absorption capacity is preferably 5 to 50 g (water absorption amount per 1 g of water absorbent resin), more preferably 10 to 50 g, and particularly preferably 20 to 50 g.

(2) Manufacturing method of water-absorbing resin sheet The water-absorbing resin sheet of the present invention is obtained by collecting the water-absorbing resin composite aggregate as a sheet-like deposit in the above-described method for manufacturing a water-absorbing resin composite aggregate. Can be obtained.

  Further, in this method for producing a water absorbent resin composite aggregate, a fiber supply means for forming a fiber deposited layer is provided in the upstream or downstream of the polymerization complexing tank, and the bottom of the water absorbent resin composite aggregate deposited layer is provided. In addition, a water absorbent resin sheet having a laminated structure of a fiber layer and a water absorbent resin composite layer can be produced by forming a fiber deposition layer thereon. Furthermore, a water-absorbing resin sheet having an arbitrary laminated structure can be produced by arranging a combination of the polymerization composite tank and the fiber supplying means or the powder water-absorbing resin supplying means.

  The water-absorbent resin sheet of the present invention can also be collected by continuously forming the sheet as described above, and opening and sieving the water-absorbent resin composite from what was once manufactured into a sheet by the above-described method. The water-absorbent resin composite can be deposited again and heat-pressed to form a sheet. In this case, the above-mentioned free fibers and / or powder water absorbent resin may be further mixed with the water absorbent resin composite to form a sheet. In addition, a water absorbent resin composite layer may be formed on the opened fiber accumulation layer to form a sheet.

  In addition, as described above, this method includes broken materials, dirt, non-standard products and returned goods from the market, and recovery of the water absorbent resin composite from the used water absorbent resin sheet, as described above. In this case, a new water-absorbent resin composite may be further mixed with the recovered water-absorbent resin composite to form a sheet.

(3) Thinning of water absorbent resin sheet The water absorbent resin sheet of the present invention may also be thinned. In that case, it is preferable that the bulk density is 0.20~1.10g / cm ^3, more preferably 0.30~0.85g / cm ^3, 0.40~0.85g / cm Even more preferred is ³ . The thickness after thinning is preferably 0.2 to 20 mm, more preferably 0.2 to 10 mm, and further preferably 0.2 to 5 mm.

  The thinning of the water absorbent resin sheet can be adjusted by conditions such as pressurization, heating, and humidification of the water absorbent resin sheet.

  As a method for thinning the water-absorbent resin sheet, for example, a press machine can be used. As a press machine, a flat plate press machine, a roll press machine, etc. can be used. The pressure is selected within a range where the water-absorbing resin particles are not broken. When the water-absorbing resin particles are broken, the water-absorbing resin is separated from the fibers and the water-absorbing resin leaks out from the water-absorbing resin sheet (or water-absorbing article). Thus, the performance of the water absorbent resin sheet (water absorbent article) is lowered.

In reducing the thickness, the heating temperature for heating can be selected at a temperature lower than the melting temperature of the fibers used. When heated above the melting temperature, the fibers are bound together to form a network, resulting in a result different from the object of the present invention. In the case of humidification, steam can be used. The vapor pressure should be lower than 1 MPa, and preferably lower than 0.5 MPa. The steam capacity per m ² is preferably 300 kg / hr or less, more preferably 100 kg / hr or less, and further preferably 50 kg / hr or less. If the amount of steam is too large, the water-absorbing resin absorbs moisture, softens and crushes or binds fibers to form a network, resulting in a result different from the object of the present invention. Moreover, since a large amount of water must be distilled off, it is not economical. The temperature of the steam used is selected within a range lower than the fiber melting temperature. If steam having a temperature higher than the fiber melting temperature is used, the fibers are bound together as described above, resulting in a result different from the object of the present invention. Further, the water-absorbing resin sheet can be humidified by adding water by spraying or the like.

[5] Water Absorbent Article Next, the water absorbent article of the present invention using the water absorbent resin sheet of the present invention will be described.
(1) Structure of water-absorbing article The structure of the water-absorbing article of the present invention can be appropriately determined according to the function and application required for the water-absorbing article. A typical water-absorbent article is formed by appropriately combining the water-absorbent resin sheet of the present invention with water-absorbing nuclei, and fluff pulp, tissue, non-woven fabric, polyolefin sheet and the like commonly used for water-absorbent articles. In particular, so-called paper diapers and sanitary napkins may be laminated with a diffusion layer of a hydrophobic fiber nonwoven fabric such as polyethylene fiber, polypropylene fiber, or polyester fiber in order to improve the diffusibility of body fluids during use.

  FIG. 3 is a cross-sectional view showing a typical configuration example of a diaper as an embodiment of the water absorbent article according to the present invention. The structure of FIG. 3 is obtained by laminating a tissue 12, preferably a thinned water-absorbent resin sheet 13, a tissue 14, and a water-permeable polyester fiber nonwoven fabric 15 in this order on a water-impermeable polyethylene sheet 11. The water absorbent article 10 can be manufactured by laminating the layers in this manner, applying pressure to bring the layers into close contact, and thermocompressing the four sides after releasing the pressure.

  In the water absorbent article 10, the aqueous liquid to be absorbed is absorbed from the water permeable polyester fiber nonwoven fabric 15 side and absorbed by the water absorbent resin sheet 13. As shown in the structure of FIG. 4, an aqueous liquid can be quickly absorbed by disposing a fibrous base material such as tissue 14 or water-permeable polyester fiber nonwoven fabric 15 on the upper part of the water-absorbent resin sheet 13. Will be able to. Moreover, even if pressure is applied to the water-absorbent article, it is possible to make it difficult to release the absorbed aqueous liquid.

Furthermore, by inserting a material imparting bulkiness such as fluff pulp into the water-absorbent article, the touch to the skin can be improved and the applicability to the body can be enhanced. Basis weight of the material giving bulkiness is preferably 80~250g / ^{m 2,} and more preferably 100~220g / ^{m 2.} The material imparting bulkiness is preferably provided between the water-absorbent resin sheet 13 and a substrate such as the water-impermeable polyethylene sheet 11, but may be provided so as to sandwich the water-absorbent resin sheet 13 from above and below. . However, when sandwiching from above and below, it is preferable that the basis weight of the lower layer of the water absorbent resin sheet is larger.

(2) Use of the water-absorbing article The water-absorbing article of the present invention includes children's paper diapers, adult paper diapers, incontinence pads, sanitary materials such as sanitary goods, water-absorbing sheets such as waste water, holding sheets, cold-retaining agents, and water-stopping materials. It can be suitably used for industrial materials such as sealing materials, anti-condensation agents for construction, soil water retention agents, water retention sheets for seedlings, freshness retention agents such as vegetables, and agricultural materials such as water retention agents.

[5] Other additional steps In the production of the water absorbent resin composite aggregate (water absorbent resin composite) and / or the water absorbent resin sheet of the present invention, as other additional steps, a residual monomer treatment step, surface cross-linking, and the like. In order to provide a process and other functions, an additive addition process such as a catalyst, a reducing agent, a deodorant, a human urine stabilizer, an antibacterial agent, etc. may be added.

<Residual monomer treatment process>
Examples of the method for treating the residual monomer include 1) a method of proceeding polymerization of the residual monomer, 2) a method of introducing the residual monomer to another derivative, and 3) a method of removing the residual monomer.

  Examples of the method 1) of proceeding the polymerization of the residual monomer include a method of further heating the water absorbent resin composite aggregate, and a method of heating after adding a catalyst or catalyst component that promotes the polymerization of the residual monomer to the water absorbent resin. And a method of irradiating ultraviolet rays, a method of irradiating electromagnetic radiation or fine particle ionizing radiation, and the like.

  In the method of further heating the water absorbent resin composite, the water absorbent resin composite is heat-treated at 100 to 250 ° C. to polymerize the monomer remaining in the water absorbent resin composite.

  The method of adding a catalyst or catalyst component that promotes the polymerization of residual monomer to the water-absorbent resin composite is that, for example, when polymerization is performed using a redox polymerization initiator, the radical generator may remain. Since there are many, what is necessary is just to provide a reducing agent solution to water absorbing resin. As the reducing agent, sodium sulfite, sodium hydrogen sulfite, L-ascorbic acid or the like used as a redox polymerization initiator may be used. Usually, these are given to the water-absorbent resin composite as a 0.5 to 5% by weight aqueous solution. . The amount of the reducing agent applied is preferably 0.1 to 2% by weight based on the dry resin. Application | coating of a reducing agent solution can be performed by arbitrary methods, such as spraying using an atomizer and immersing in a reducing agent solution. The water-absorbent resin composite provided with the reducing agent is then heated to polymerize the polymerizable monomer. Heating may be performed, for example, at 100 to 150 ° C. for about 10 to 30 minutes. Although the water content of the water-absorbent resin composite is lowered by this heating, if the water content is high, the water-absorbing resin composite is further dried with a drier to form a product water-absorbing material.

  In the method of irradiating the water-absorbent resin composite with ultraviolet rays, an ordinary ultraviolet lamp may be used. Irradiation intensity, irradiation time and the like vary depending on the type of fiber used, the amount of residual monomer impregnation, etc. The lamp is 10 to 200 W / cm, preferably 30 to 120 W / cm, the irradiation time is 0.1 second to 30 minutes, and the lamp-complex distance is 2 to 30 cm. The water content in the water-absorbent resin composite at this time is generally 0.01 to 40 parts by weight, preferably 0.1 to 1.0 parts by weight, based on 1 part by weight of the polymer. Is done. A water content of less than 0.01 parts by weight or more than 40 parts by weight is not preferable because it significantly affects the reduction of residual monomers. As an atmosphere when irradiating with ultraviolet rays, any of vacuum, presence of an inorganic gas such as nitrogen, argon, helium, or air can be used. The irradiation temperature is not particularly limited, and the object can be sufficiently achieved at room temperature. There is no restriction | limiting in particular also in the ultraviolet irradiation apparatus to be used, Arbitrary methods, such as the method of irradiating for a fixed time for a fixed time, or the method of irradiating continuously with a belt conveyor, can be used.

  High energy radiation such as accelerated electrons and gamma rays is used for the method of irradiating the water absorbent resin composite. The dose to be irradiated varies depending on the amount of residual monomer in the composite, the amount of water, and the like, but is generally 0.01 to 100 megarads, preferably 0.1 to 50 megarads. When the dose exceeds 100 megarads, the amount of water absorption becomes extremely small. When the dose is less than 0.01 megarad, the water absorption capacity and the water absorption speed intended in the present invention are large, and it is difficult to obtain a particularly small residual monomer. The water content of the water-absorbent resin composite at this time is generally 40 parts by weight or less, preferably 10 parts by weight or less, based on 1 part by weight of the polymer. If the amount of water exceeds 40 parts by weight, the effect of improving the water absorption rate is small, and particularly the reduction of the residual monomer is significantly affected. As an atmosphere for irradiating the composite with high energy radiation, any of vacuum, presence of an inorganic gas such as nitrogen, argon, helium, or air can be used. A preferable atmosphere is air. When irradiation is performed in the air, the water absorption capacity and the water absorption speed are large and the residual monomer is particularly small. Moreover, there is no restriction | limiting in particular in irradiation temperature, The objective can fully be achieved at room temperature.

  Examples of the method of introducing the residual monomer of 2) to other derivatives include a method of adding an amine, ammonia and the like, and a method of adding a reducing agent such as bisulfite, sulfite and pyrosulfite.

  Examples of the method 3) for removing the residual monomer include extraction with an organic solvent and distillation. In the method of extracting with an organic solvent, the water-absorbent resin composite is immersed in a water-containing organic solvent to extract and remove residual monomers. As the water-containing organic solvent, ethanol, methanol, acetone or the like can be used, and the water content is preferably 10 to 99% by weight, particularly preferably 30 to 60% by weight. Generally, the higher the water content, the higher the ability to remove the residual monomer. However, when a water-containing organic solvent having a high water content is used, the energy consumption in the subsequent drying step increases. The time for immersing the complex in the water-containing organic solvent is usually about 5 to 30 minutes, and it is also preferable to adopt a means for promoting the extraction of the residual monomer such as shaking the complex. After the immersion treatment, it is usually treated with a dryer and dried.

  As a method for distilling off the residual monomer, there is a method of treating the composite with superheated steam or a steam-containing gas. For example, the residual monomer in the water-absorbent resin can be reduced by heating saturated steam at 110 ° C. to 120 to 150 ° C. and bringing it into contact with the composite as superheated steam. In this method, when water in the water-absorbent resin evaporates as water vapor, it is considered that residual monomers are vaporized at the same time and escape from the water-absorbent resin. According to this method, it is possible to both remove the residual monomer and dry the product.

<Surface cross-linking process>
In addition, for the purpose of improving the water absorption performance, the surface of the water absorbent resin can be crosslinked with a crosslinking agent. In general, it is known to improve the properties of resin particles by applying an appropriate amount of moisture together with a crosslinking agent to the surface of powdered water-absorbent resin particles, and then heating to crosslink the surface. As a result of the formation of a crosslinked structure, it is considered that the shape can be maintained without inhibiting the swelling when water is absorbed and swollen. In this step, first, a solution of a surface cross-linking agent is applied to the water absorbent resin sheet. As the surface cross-linking agent, polyfunctional compounds that can be copolymerized with polymerizable monomers such as N, N′-methylenebis (meth) acrylamide and (poly) ethylene glycol di (meth) acrylate, (poly) ethylene glycol diglycidyl ether, etc. A compound having a plurality of functional groups capable of reacting with the carboxylic acid group is used. These surface cross-linking agents are usually used in an amount of 0.1 to 1% by weight, preferably 0.2 to 0.5% by weight, based on the amount of dry water absorbent resin of the water absorbent resin composite. These surface cross-linking agents are diluted with water, ethanol, methanol, or the like so as to be uniformly applied to the entire water-absorbent resin sheet, and 0.1 to 1% by weight, particularly 0.2 to 0.5% by weight. % As a solution. The application of the cross-linking agent solution is usually preferably carried out by spraying the cross-linking agent solution onto the water-absorbent resin sheet using a sprayer or applying the cross-linking agent solution with a roll brush. In addition, after providing a crosslinking agent solution excessively, you may make it remove excessive surplus crosslinking agent solution by squeezing lightly to such an extent that a resin particle is not crushed with a pressing roll, or blowing a wind. The application of the crosslinking agent solution may be performed at room temperature. The direction which gave the crosslinking agent solution after providing the particle | grains in the middle of superposition | polymerization can provide a crosslinking agent efficiently to water absorbing resin. The water absorbent resin sheet to which the crosslinking agent solution has been applied is then heated to cause the crosslinking reaction to proceed, and a crosslinked structure is selectively formed on the surface of the water absorbent resin. The conditions for the cross-linking reaction may be appropriately selected depending on the cross-linking agent to be used. In the present invention, an unsaturated carboxylic acid polymer crosslinked product is preferred as the water-absorbing crosslinked resin, and a partially neutralized acrylic acid polymer crosslinked product is particularly preferred.

<Additive addition process>
Various additives can be added to the water absorbent resin composite aggregate or the water absorbent resin sheet in order to impart a desired function depending on the intended use. Examples of these additives include a stabilizer for preventing polymer degradation and alteration due to a liquid that absorbs water, an antibacterial agent, a deodorant, a deodorant, a fragrance, and a foaming agent.

  Among these, as a stabilizer to prevent polymer degradation and alteration due to the liquid that absorbs water, the degradation and alteration of the water-absorbent resin due to excrement (ie human urine, feces) and body fluids (body fluids such as human blood, menstrual blood, and secretions). Stabilizers to prevent are mentioned. JP-A-63-118375 discloses a method for containing an oxygen-containing reducing inorganic salt and / or an organic antioxidant in a polymer, JP-A-63-153060 discloses a method for containing an oxidizing agent, JP 63-127754 A contains an antioxidant, JP 63-272349 A contains a sulfur-containing reducing agent, JP 63-146964 contains a metal chelating agent. JP-A 63-15266 discloses a method containing a radical chain inhibitor, JP-A 1-275661 discloses a phosphinic acid group- or phosphonic acid group-containing amine compound or a salt thereof, Japanese Laid-Open Patent Application No. 64-29257 discloses a method of containing a polyvalent metal oxide, Japanese Patent Application Laid-Open No. 2-255804, and Japanese Patent Application Laid-Open No. 3-179008. A method in which the coexistence of Tokimizu soluble chain transfer agents have been proposed. All of these can be used in the present invention. In addition, JP-A-6-306202, JP-A-7-53884, JP-A-7-62252, JP-A-7-113048, JP-A-7-145326, JP-A-7-145263, The materials and methods described in JP-A-7-228788 and JP-A-7-228790 can also be used. Specific examples include potassium oxalate titanate, tannic acid, titanium oxide, phosphinic acid amine (or salt thereof), phosphonic acid amine (or salt thereof), metal chelate and the like. Of these, stabilizers against human urine, human blood, and menstrual blood are sometimes referred to as human urine stabilizer, human blood stabilizer, and menstrual blood stabilizer, respectively.

  Antibacterial agents are used to prevent spoilage due to absorbed liquid. As antibacterial agents, for example, “New development of bactericidal / antibacterial technology”, pages 17-80 (Toray Research Center (1994)), “Testing / evaluation methods and product design of antibacterial / antifungal agents”, pages 128-344 (NTT) S (1997)), Japanese Patent No. 2760814, Japanese Unexamined Patent Publication No. 39-179114, Japanese Unexamined Patent Publication No. 56-31425, Japanese Unexamined Patent Publication No. 57-25813, Japanese Unexamined Patent Publication No. 59-189854, JP 59-105448, JP 60-158861, JP 61-181532, JP 63-135501, JP 63-139556, JP 63-156540. JP-A-64-5546, JP-A-64-5547, JP-A-1-153748, JP-A-1-221242, JP-A-2-253. No. 47, JP-A-3-59075, JP-A-3-103254, JP-A-3-221141, JP-A-4-11948, JP-A-4-92664, JP-A-4-138165. JP-A-4-266947, JP-A-5-9344, JP-A-5-68694, JP-A-5-161671, JP-A-5-179053, JP-A-5-269164, Those introduced in JP-A-7-165981 can be appropriately selected.

  Examples thereof include alkylpyridinium salts, benzalkonium chloride, chlorhexidine gluconate, pyridione zinc, silver-based inorganic powders, and the like. Representative examples of quaternary nitrogen-based antibacterial agents include methylbenzethonium chloride, benzalkonium chloride, dodecyltrimethylammonium bromide, tetradecyltrimethylammonium bromide, and hexadecyltrimethylammonium bromide. Examples of the heterocyclic quaternary nitrogen-based antibacterial agents include dodecylpyridinium chloride, tetradecylpyridinium chloride, cetylpyridinium chloride (CPC), tetradecyl-4-ethylpyridinium chloride, and tetradecyl-4-methylpyridinium chloride.

  Other preferred antibacterial agents include bis-biguanides. These are described in detail, for example, in US Pat. Nos. 2,684,924, 2,990,425, 2,830,006 and 2,863,019. The most preferred bis-biguanide is 1,6-bis (4-chlorophenyl) diguanide hexane, known as chlorohexidine and its water-soluble salts. Particularly preferred are chlorohexidine hydrochloride, acetate and gluconate.

  Several other types of antibacterial agents are also useful. For example, carbanilides, substituted phenols, metal compounds, and rare earth salts of surfactants can be exemplified. The carbanilide includes 3,4,4′-trichlorocarbanilide (TCC, triclocarban) and 3- (trifluoromethyl-4,4′-dichlorocarbanilide (IRGASAN). Mention may be made of 5-chloro-2- (2,4-dichlorophenoxy) phenol (IRGASAN DP-300), which include graphite and tin salts such as zinc chloride, zinc sulfide and tin chloride. A rare earth salt of a surfactant is disclosed in European Patent Publication No. 10819. As this type of rare earth salt, a linear lanthanum salt of a C10-18 alkylbenzene sulfonate can be exemplified.

  In addition, deodorants, deodorizers, and fragrances are used to prevent or alleviate the unpleasant odor of the absorbed liquid. Examples of the deodorant, deodorant, and fragrance are “new deodorant / deodorant and technology and prospect” (Toray Research Center (1994)), JP-A-59-105448, JP-A-60-158861, JP-A-61-118132, JP-A-1-153748, JP-A-1-221242, JP-A-1-265156, JP-A-2-41155, JP-A-2-253847, Those introduced in Japanese Laid-Open Patent Publication No. 3-103254, Japanese Laid-Open Patent Publication No. 5-269164, and Japanese Laid-Open Patent Publication No. 5-277143 can be appropriately selected. Specifically, examples of the deodorizer and deodorizer include iron complexes, tea extraction components, and activated carbon. Examples of fragrances include fragrances (citral, cinnamic aldehyde, heliotopine, camphor, bornyl acetate) wood vinegar, paradichlorobenzene, surfactants, higher alcohols, terpene compounds (limonene, pinene, camphor, borneol, eucalyptol, Eugenol).

  A foaming agent and a foaming aid can be used in combination to increase the porosity and the surface area in order to improve the water absorption performance of the water absorbent resin. As the foaming agent and foaming aid, for example, those introduced in “Rubber / Plastic Compounding Chemicals” (Rubber Digest, 1989, pages 259 to 267) can be appropriately selected. Examples include sodium bicarbonate, nitroso compounds, azo compounds, sulfonyl hydrazides and the like.

  These additives are appropriately added according to the purpose and action mechanism in each step of manufacturing the water absorbent resin sheet. For example, the foaming agent is suitably added in the production process of the water-absorbent resin composite aggregate, and is preferably added before the polymerization process or during the polymerization process. Human urine stabilizer, human blood stabilizer, antibacterial agent, deodorant, and fragrance can be added in the manufacturing process of the water-absorbent resin composite assembly, the manufacturing process of the water-absorbing resin sheet, and the manufacturing process of the water-absorbing article. is there. Of course, it can be applied to the fibers in advance. Moreover, you may add these additives in components other than the water absorbing resin sheet which comprises a water absorbing article.

  Further, the water-absorbent resin sheet and the water-absorbent article of the present invention include JP-A 63-267370, JP-A 63-10667, JP-A 63-295251, JP-A 63-270801. JP-A 63-294716, JP-A 64-64602, JP-A-1-231940, JP-A-1-243927, JP-A-2-30522, JP-A-2-153373. The technique utilized for the sheet-like water-absorbing material proposed in Japanese Patent Laid-Open No. 3-213385, Japanese Patent Laid-Open No. 4-133728, Japanese Patent Laid-Open No. 11-156188, or the like may be appropriately used depending on the purpose. it can.

  The following examples further illustrate the present invention and illustrate its effectiveness. However, such examples do not limit the scope of the invention. In the following examples, “%” means “% by weight” unless otherwise specified.

[Example 1]
Neutralization was carried out by adding 3.3 parts by weight of water to 100 parts by weight of acrylic acid and adding 133.3 parts by weight of a 25% by weight aqueous sodium hydroxide solution to 25 ° C. or lower under cooling. Solution A was prepared by adding 0.14 parts by weight of N, N′-methylenebisacrylamide as a crosslinking agent and 4.55 parts by weight of a 31% by weight hydrogen peroxide aqueous solution as an oxidizing agent to the resulting partially neutralized acrylic acid aqueous solution. Prepared. The monomer concentration of solution A was 50% by weight, and the degree of neutralization was 60 mol%.

  Separately, 100 parts by weight of the partially neutralized acrylic acid aqueous solution prepared in the same manner as described above, 0.14 parts by weight of N, N′-methylenebisacrylamide as a crosslinking agent and L-ascorbic acid as a reducing agent Solution B was prepared by adding 0.57 parts by weight.

  The prepared solution A and solution B are each heated to a temperature of 40 ° C., and are respectively supplied from the two-component mixed type monomer spray nozzle 103 disposed in the lower center portion of the inner cylinder 102 of the polymerization composite tank 100 shown in FIG. The pump was supplied so that the flow rate would be 400 g / min.

  On the other hand, pulp fibers (manufactured by Wafer User: NB416, average fiber diameter 0.22 dtex) opened from the upper fiber supply port 107 (a disentanglement machine not shown is provided above the fiber supply port 107). 300, average fiber length 2.5 mm, water contact angle 0 °) 300 was fed in a multiphase flow with air (fiber feed rate 50 g / min). At that time, the temperature of the air in the multiphase flow was 50 ° C., and the linear velocity was 1 m / sec.

  The sprayed monomer droplet 200 immediately rises in the inner cylinder 102 along the air curtain 105 of the surrounding vapor (discharge speed 1 m / sec) while immediately starting polymerization, and has a height of about 1.6 m (polymerization). (Rate 40%) (in air, temperature 50 ° C.) and exceeded the upper end of the peripheral wall of the inner cylinder 102 (height 140 cm). When the upper end of the inner cylinder 102 is exceeded, the droplet 200 in the process of polymerization and the non-molded fiber 300 from the fiber supply port 107 come into contact with each other, and the fiber is bonded and / or embedded in the droplet 200, It dropped between 102 and the outer cylinder 101. The floating pulp fibers that did not come into contact with the droplet 200 again entered the inner cylinder 102 through the circulating flow through the gap between the nozzle 103 and the inner cylinder 102 and rose. The composite 400 was collected as a deposit on the wire mesh belt conveyor 108 installed 1 m below the nozzle 103. In addition, it controlled so that the pressure difference of a mesh upper and lower might be 1,000 Pa by attracting | sucking with a blower under a mesh. Further, the collected material was dried with a hot air dryer at 120 ° C. for 3 hours, and then the fibers that were not bonded or embedded were screened with an air classifier to obtain a water absorbent resin composite aggregate.

  The polymerization rate of the monomer at the position of collision with the fiber, the average diameter of the droplets, and the water contact angle of the fiber used were measured by the following procedure.

<Average droplet diameter>
It was calculated according to the following formula from the average particle diameter dp and monomer concentration ((acrylic acid + sodium acrylate) concentration) C _m of the water-absorbent resin particles forming the later-described water-absorbent resin composite.
Droplet diameter dd = dp / (C _m ) ^1/3

<Measurement of monomer polymerization rate>
A beaker containing methanol was installed so that the liquid level of methanol was located at the position where the fiber was introduced, and droplets of the reaction mixture that started polymerization were formed in the gas phase. Drops were allowed to fall. The monomer weight Mm (g) in methanol was measured by liquid chromatography. Further, after the polymer in methanol was dried under reduced pressure at 130 ° C. for 3 hours, the polymer weight Mp (g) was measured. From these values, the polymerization rate was calculated by the following formula.

<Water contact angle of fiber>
(1) A solution having a concentration of 1 to 10% by weight was prepared using a solvent capable of dissolving and dispersing fibers.
(2) The solution was thinly spread on a petri dish, and the solvent was gently evaporated with dry air at room temperature. After sufficiently drying, a thin film-like molded product was obtained.
(3) The contact angle of distilled water at room temperature with respect to the air surface of the film-like molded product was determined. The contact angle was measured using an automatic contact angle meter CA-V type (manufactured by Kyowa Interface Science Co., Ltd.).

To the obtained water-absorbent resin composite aggregate, the same non-molded fiber as used in the production of this water-absorbent resin composite aggregate is added, and finally the weight ratio of the water-absorbent resin and the non-molded fiber is 90. : A water-absorbent resin composite composition of 10 was obtained, and this water-absorbent resin composite composition was placed on a stainless steel plate so that the amount of the water-absorbent resin was 300 g / m ^2. Densification was performed over 30 minutes under the conditions of pressure: 100 kg / cm ² (9.8 MPa) and temperature: 25 ° C.

[Example 2]
In Example 1, the height of the inner cylinder 102 is set to 60 cm, and the solution A and the solution B are supplied from the two-component mixed type monomer spray nozzle 103 at a flow rate of 200 g / min, respectively. It was changed to 5 m / sec and blown up to a height of about 0.8 m (polymerization rate 15%), and the water-absorbent resin composite assembly was assembled in the same manner except that the pulp fiber supply rate was 25 g / min. A water-absorbent resin sheet was produced in the same manner.

Example 3
In Example 1, a water absorbent resin composite was prepared in the same manner as in Example 1 except that nylon fibers having an average fiber diameter of 1.7 dtex, an average fiber length of 0.9 mm, and a water contact angle of 50 ° were used instead of pulp fibers. An aggregate was obtained and a water-absorbent resin sheet was produced in the same manner.

[Comparative Example 1]
Using the same operating conditions as in Example 1 of JP-A-11-93073, the water-absorbent resin particles are uniformly fixed over the entire polyester fiber, and the coalescence of the water-absorbent resin particles is hardly observed. A nonwoven fabric water-absorbent resin composite having a network formed thereon was obtained, and a water-absorbent resin sheet was produced in the same manner.

[Comparative Example 2]
A water-absorbent resin composite aggregate was produced using a side wall fiber-injection type polymerization composite tank 100A shown in FIG. 4, members having the same functions as those shown in FIG. 2 are denoted by the same reference numerals.

  This polymerization composite tank 100A is provided with inlets 111 and 112 of fibers (non-molded fibers) 300 on the side peripheral wall of a cylinder 110, and a monomer for ejecting a liquid material containing a polymerizable monomer in the upper part. A spray nozzle 103 is provided, and liquid supply pipes 104 </ b> A and 104 </ b> B are connected to the nozzle 103. In addition, an air supply pipe 106 and an air curtain forming means (not shown) for supplying steam-containing air to the outer peripheral portion of the nozzle 103 to form the steam air curtain 105 are provided. A belt conveyor 108 is provided below the polymerization composite tank 100A.

  A solution A and a solution B were prepared under the same conditions and operations as in Example 1. The prepared solutions A and B were heated to a liquid temperature of 40 ° C., respectively, and the cylinder of the polymerization composite tank 100A shown in FIG. 110 was supplied from a two-component mixed spray nozzle 103 provided at the upper center of 110 so as to have a flow rate of 400 g / min. The atomized monomer droplet 200 dropped in the cylinder 110 while immediately starting polymerization (in air, temperature 50 ° C.). A fiber supply port installed at 0.8 m (polymerization rate: 15%) and 1.6 m (polymerization rate: 40%) below the tip of the nozzle (this fiber supply port is provided with a defibrating machine not shown) 111, Pulp fibers opened from No. 112 (manufactured by Wafer User: NB416, average fiber diameter 0.22 dtex, average fiber length 2.5 mm, water contact angle 0 °) were respectively supplied in a multiphase flow with air (230 g / Min). At that time, the temperature of the air in the multiphase flow was 50 ° C., and the linear velocity was 1 m / sec. The superposed droplet 200 and non-molded fiber 300 are in contact with each other, and the fiber 300 is adhered and / or embedded in the droplet 200 and deposited as a deposit on the wire mesh belt conveyor 108 installed 3 m below the nozzle 103. It was recovered. In addition, it controlled so that the pressure difference of a mesh upper and lower might be 1,000 Pa by attracting | sucking with a blower under a mesh. Further, the collected material was dried with a hot air dryer at 120 ° C. for 3 hours, and then the fibers that were not bonded or embedded were screened with an air classifier to obtain a water-absorbent resin composite aggregate, which was used in Example 1. In the same manner, a water-absorbent resin sheet was produced.

[Comparative Example 3]
A commercially available high water-absorbent resin (manufactured by Sundia Polymer Co., Ltd .: DS51) was used to produce a water-absorbent resin sheet by mixing the pulp equivalent to the pulp used in Example 1 with pulp.

[Test example]
The following evaluation was performed about the water-absorbent resin composite aggregate (water-absorbent resin composite) and the water-absorbent resin sheet obtained in Examples and Comparative Examples, and the results are shown in Table 1 together with the production conditions.

(1) Opening and sieving properties The weight (K1) of the water-absorbing resin sheet was measured, and the water-absorbing resin composite was recovered by applying the forced opening and sieving machine shown in FIGS. 5 (a) and 5 (b). .

The spreader 51 shown in FIG. 5 (a) has an outer diameter of 5 cm and a length of 20 cm on the surface of acrylic cylinders 51A and 51B provided with stainless steel pins 52 having a thickness of 1 mm and a length of 1 cm at intervals of 5 mm. The cylinder 51A rotates in the same direction at a rotation speed of 500 rpm and the cylinder 51B rotates at the rotation speed of 900 rpm. Further, the sieving machine 53 shown in FIG. 5B has a stirring blade 55 having an outer diameter of 8 cm and a 10-mesh metal mesh 56 having a diameter of 9 cm in an acrylic cylinder 54 having an inner diameter of 9 cm. The pipe portion 57 is provided with a 100-mesh wire net 58 having a diameter of 5 cm, and is sieved with reduced pressure-60 mmH ₂ O.

  The weight (K2) of the residue remaining on the 100 mesh wire net was measured, and the opening and sieving properties of the water absorbent resin sheet were evaluated according to the following formula.

(2) Weight ratio of water-absorbing resin / fiber, surface-bonded fiber / partially embedded fiber ・ Weight measurement of surface-bonded fiber In a 5 L beaker charged with 4500 ml of distilled water, magnetic stirrer (50 mm cylindrical, 300 rpm) Under stirring, 3 g (W1) of the water-absorbent resin composite aggregate (water-absorbent resin composite) weighed with a lower four-digit electronic balance was slowly added and allowed to equilibrate and swell for 6 hours. The fibers adhering to the surface were peeled off by stirring and floated. Stirring was stopped, the floating fiber was decanted and filtered through a 200 mesh wire mesh.

  Furthermore, distilled water was added so that it might become 4500 ml, it stirred for 10 minutes, the floating fiber was decanted, and it filtered with the 200 mesh metal-mesh. By repeating this operation three times, the floating fibers were hardly visible. The fibers collected in the wire mesh were dried at 100 ° C. for 3 hours, and the weight (W2) was measured with a lower 4-digit electronic balance.

・ Weight measurement of partially embedded fiber The water-containing gel remaining in the decantation was gradually added to a 2 L beaker containing 1000 ml of ethanol with a magnetic stirrer (50 mm cylindrical shape, 300 rpm) while stirring to remove moisture from the water-containing gel. Removed and collected by filtration as a white solid. In a 300 ml beaker containing 200 ml of distilled water, 3.0 g of potassium persulfate was dissolved while stirring with a magnetic stirrer (25 mm, cylindrical shape 100 rpm). After dissolution, each of the collected color solids was slowly added and allowed to swell for 6 hours. After completion of the equilibrium swelling, it was left in a dryer at 100 ° C. for 6 hours. After leaving, it was put into a 200 mesh wire mesh screen having an inner diameter of 25 cm. After recovering the magnetic stirrer, the water-soluble gel was filtered so as to be lined with a 70 mm wide silicone rubber spatula. The fiber remaining on the sieve was distilled several times, washed several times, collected and dried at 100 ° C. for 3 hours, and the weight (W3) was measured with a lower 4-digit electronic balance.

  As a control experiment, the fiber alone was treated in the same manner. In the weight measurement of the surface adhesive fiber and the weight measurement of the partially embedded fiber, almost 100% was recovered.

The weight ratio was calculated by the following formula.
Water-absorbing resin / fiber weight ratio = {W1- (W2 + W3)} / (W2 + W3)
Surface adhesive fiber / partially embedded fiber weight ratio = W2 / W3

(3) Average particle diameter of water-absorbent resin particles Take an optical micrograph of the sample after the opening and sieving measurement of (2), select 100 water-absorbent resin particles arbitrarily, and measure their long diameter The average value was defined as the average particle size (μm).

(4) Measurement of physiological saline water absorption capacity A 1,000 ml physiological saline solution having a concentration of 0.9% by weight was placed in a 2000 ml beaker. About 1.0 g of the sample after the opening and sieving measurement of (2) was put in a 250 mesh nylon bag (10 cm × 20 cm in size), and the bag was immersed in the physiological saline for 30 minutes. Next, the nylon bag was pulled up, and the weight after draining for 15 minutes was measured, and this was designated as W4 (g). Also, as a blank, prepare a fiber having the same weight as the fiber contained in the water-absorbent resin sheet used for the measurement of W4, and measure the weight after the physiological water absorption by the same method as W4. W5 (g). The weight of the water-absorbent resin contained in the water-absorbent resin sheet used for the measurement of W4 was defined as W6 (g). The physiological saline water absorption capacity of the water absorbent resin sheet was calculated according to the following formula.

(5) Artificial urine flow rate A faucet at the lower end and a glass filter (Geneal glass filter 30G1, pore diameter 100-130 μm) at the top, an inner diameter of 25.6 mm, and a height above the filter of about 40 cm Glass cylinders (General Biocolumn CF-30) were prepared. Marks were provided at positions of 100 ml, 150 ml and 200 ml from the upper surface of the glass filter. Room-temperature artificial urine (the composition is as follows) was placed in this glass cylinder up to the position of the 200 ml mark, and then 0.50 g of the water-absorbent resin composite was placed. After 30 minutes have elapsed, the glass cylinder is turned upside down 10 times (interval 5 seconds). Subsequently, the cock was opened, and the liquid level was lowered to the position of the 100 ml mark. The artificial urine was poured to the position of the marked line of 200 ml while taking care so that the cock was closed and the water-absorbent resin composite did not rise. After confirming that the water-absorbent resin composite has settled (floating fibers can be ignored), the cock is opened to allow the liquid to flow out, and the liquid level is 150 ml and 100 ml. The passage time (T seconds) between the lines was measured, and the liquid passing speed was calculated by the following formula. When the water-absorbing resin composite is not present, the time required for the liquid level to pass between the 150 ml mark and the 100 ml mark is 10.5 seconds.
Flow rate = 50 / (T-10.5) (ml / sec)
(Artificial urine composition)
Urea: 1.94%
Sodium chloride: 0.80%
Calcium chloride: 0.06%
Magnesium sulfate: 0.11%
Distilled water: 97.09%

(6) Thickness The water-absorbent resin sheet was cut into 5 cm × 5 cm, and the thickness was measured by the method shown in FIG. 6 in accordance with JIS 1-1096.
(1) Attach an adapter 31 with a diameter of 30 mm to a rheometer (FUDOH product, model number: NRM-2003J), the sample stage 32 rises at a speed of 2 cm / min, and stops when a pressure of 0.2 psi is applied It was set as follows.
(2) Set the sample (water absorbent resin sheet) 33 on the measurement table and raise the sample table 32 to reach the pressure of 0.2 psi and stop from the upper surface of the adapter 31 to the lower surface of the sample table 32. The distance t was measured using a caliper.
(3) Five samples were measured and the average value was obtained.
(4) A blank measurement was performed at the same time without placing the sample on the sample table 32.
(5) The thickness was obtained from the following formula.
Thickness (mm) = Sample measurement value (mm)-Blank measurement value (mm)

(7) Bulk density The weight of a 5 cm x 5 cm sample (water absorbent tree sheet) was determined, and the bulk density was determined from the following formula. Five samples were measured and the average value was obtained.

(8) Rigid softness The water-absorbent resin sheet is cut into 2 cm × 25 cm, stored at a temperature of 25 ° C. and a humidity of 50 ° C. all day and night, and then the heart loop method used for a relatively soft fabric of JIS L-1096 shown in FIG. The bending resistance was measured.
(1) A sample piece 42 was attached to a horizontal bar grip 41 shown in FIG. 7 in a heart loop shape so that the effective length of the sample piece 42 was 20 cm.
(2) After 1 minute, the distance L (cm) between the top of the horizontal bar and the lowest point of the loop was measured. Here, L was defined as bending resistance. Five samples were measured and the average value was obtained. The larger the measured value, the softer the value.

(9) Restoration rate The water-absorbent resin sheet is placed in a 5 cm x 5 cm size mold and compressed at a pressure of 1 MPa over 10 minutes, and then stored for 30 days at a temperature of 25 ° C and a humidity of 50 ° C. The thickness was measured by the thickness measurement method and calculated by the following formula. Five samples were measured and the average value was obtained.

(10) Water-absorbing resin drop-off rate
(1) The water absorbent resin sheet was cut into a size of 10 cm × 10 cm, and the weight was measured. The total amount of water absorbent resin was determined from the weight ratio of the water absorbent resin in the water absorbent resin sheet. As shown in FIG. 8, the square of the water-absorbent resin sheet 60 cut out in a standard screen sieve (inner frame dimensions: inner diameter 150 mm, depth 45 mm, 20 mesh) 67 defined in JISZ8801 is fixed to the center with a tape 68. .
(2) In this way, in the product manufactured by Tokyo Shinohara Co., Ltd., model number SS-S-228 type low tap type shaker (JIS Z8815) 69 shown in FIG. .
(3) Set the number of impulses: 165 times / minute, the number of rotations: 290 times / minute, measure the weight of the water-absorbent resin composite released from the water-absorbent resin sheet after 60 minutes of shaking, and measure the water-absorbent resin composite. The amount of the water-absorbing resin dropped off was determined from the polymerization ratio of the water-absorbing resin in the inside, and the dropping rate was determined from the following formula.

(11) Gel drop-off rate The drop-off rate of the water-absorbing gel of the water-absorbent resin sheet when a force acting so as to rub the water-absorbent resin sheet was repeatedly applied was measured by the following procedure.
(1) As shown in FIG. 10, a sample (water absorbent resin sheet) 62 is placed on a surface smoothing table 61, and a cylinder 63 having an open inner diameter of 40 mm is attached to the center and surrounded by the cylinder 63. An acrylic plate 65 (100 × 100 × 10 mm, total weight 150 g) provided with seven through-holes 64 having a diameter of 5 mm at almost equal intervals was placed in the portion. Further, a metal disc 66 (1500 g) having a diameter of 100 mm and having a hole 66 </ b> A having a diameter of 45 mm in the center portion was inserted into the cylinder 63 and mounted thereon.
(2) 150 ml of artificial urine was placed in the cylinder 63 and absorbed by the water absorbent resin sheet.
(3) After complete water absorption, the sample was allowed to stand at room temperature for 30 minutes, and as shown in FIG. 11, 72 cm was cut from the center 71 of the water-absorbent resin sheet 70, and the weight of the cut portion (sample 73) was measured.
(4) After the measurement, as shown in FIG. 12, this sample 73 is placed on the center of a 20 cm × 20 cm acrylic plate 74 and a load (3 kg) 75 having the same bottom area (10 cm × 10 cm) as the cut sample is applied. It was mounted so as not to protrude according to the shape.
(5) Set the sample so that the cut end of the sample is perpendicular to the moving direction of the shaker (Inoue Seieido Co., Model No. “MS-1”), and the amplitude is 50 mm and the frequency is 80 times / minute. And shaken for 30 minutes.
(6) The load after shaking was removed, the weight of the water-absorbing gel dropped from the sample was measured, and the gel drop-off rate was calculated using the following formula.

  From Table 1, it can be seen that the water-absorbent resin sheet provided by the present invention is excellent in water absorption, shape retention stability, and flexibility, and can easily collect and reuse the water-absorbent resin composite.

  The water-absorbent resin sheet of the present invention using the water-absorbent resin composite according to the present invention is a sanitary material such as disposable diapers and sanitary products, industrial materials necessary for water absorption and retention such as waste water, freshness retaining agents such as vegetables and water retention It is extremely useful industrially as a water-absorbing article such as an agricultural material such as an agent.

It is a schematic explanatory drawing which shows embodiment of the water absorbent resin composite which comprises the water absorbent resin composite aggregate | assembly of this invention. It is a schematic explanatory drawing which shows an example of embodiment of the manufacturing method of the water absorbent resin composite aggregate | assembly of this invention. It is a transverse cross section showing an embodiment of a water absorptive article of the present invention. 6 is a schematic explanatory view showing a polymerization composite tank used in Comparative Example 2. FIG. Fig.5 (a) is a schematic diagram which shows the external appearance of the opening machine used for evaluation of opening and sieving property, and FIG.5 (b) is a schematic diagram which shows the external appearance of the sieving machine. It is sectional drawing which shows a thickness measuring tool. It is the schematic which shows the jig | tool which measures the bending resistance by the heart loop method, (a) A figure is a perspective view, (b) A figure is sectional drawing which follows the BB line of (a) figure. It is the schematic which shows the measuring method of the water absorbent resin drop-off rate. It is the schematic which shows a low tap type shaker. It is sectional drawing which shows the water absorption method in a gel drop-off rate measurement. It is a top view which shows the cutting line of the sample in a gel drop-off rate measurement. It is sectional drawing which shows the state at the time of shaking in a gel drop-off rate measurement.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Water absorbent resin particle 2A Surface adhesive fiber 2B Partially embedded fiber 3A, 3B, 3C Water absorbent resin composite 10 Absorbent article 11 Water impermeable polyethylene sheet 12 Tissue 13 Water absorbent resin sheet 14 Tissue 15 Water permeable polyester fiber Nonwoven fabric 31 Adapter 32 Sample stand 33 Sample 41 Grasp 42 Sample 51 Opening machine 53 Sieving machine 60 Water absorbent resin sheet 62 Sample 63 Cylindrical 65 Acrylic plate 66 Disk 67 Net sieve 69 Low tap type shaker 70 Water absorbent resin sheet 73 Sample 74 Acrylic plate 75 Load 100 Polymerization composite tank 101 Outer cylinder 102 Inner cylinder 103 Monomer spray nozzle 105 Steam air curtain 108 Belt conveyor 200 Droplet 300 Fiber 400 Composite 500 Water-absorbing resin composite collection Thing

Claims (10)

A plurality of water-absorbent resin composites comprising one or more fibers bonded and / or embedded in one water-absorbent resin particle from a polymerizable monomer and fiber that form a water-absorbent resin by polymerization. A method for producing an assembly formed by assembly,
In the gas phase, liquid droplets containing the polymerizable monomer before polymerization and / or polymerization in progress are brought into contact with the fibers in the countercurrent direction, and then polymerization of the polymerizable monomer is performed. A gas phase polymerization step to proceed;
And a depositing step of depositing the fiber resin composite obtained in the gas phase polymerization step.   2. The method for producing a water-absorbent resin composite assembly according to claim 1, wherein in the gas phase polymerization step, 10 to 2000 parts by weight of the droplets are supplied to 100 parts by weight of the fibers.   3. The water absorbent according to claim 1, wherein fibers that are not bonded or embedded in the water absorbent resin particles are collected from the deposit obtained in the deposition step and supplied to the gas phase polymerization step. For producing a conductive resin composite aggregate.   A water absorbent resin composite aggregate comprising a plurality of water absorbent resin composites each having one water absorbent resin particle and one or more fibers adhered and / or embedded in the water absorbent resin particle. The weight of the fibers embedded in the water absorbent resin particles contained in the water absorbent resin composite aggregate is equal to or greater than the weight of the fibers adhered to the water absorbent resin particles, and the aggregate is opened. Alternatively, a water absorbent resin composite aggregate characterized by being sieving.   The number of fibers embedded in the water-absorbent resin particles is 50% of the total number of fibers adhered and / or embedded in the water-absorbent resin particles contained in the aggregate of water-absorbent resin composites according to claim 4. A water-absorbent resin composite aggregate characterized by the above.   6. A water absorbent resin composite assembly according to claim 4, wherein the water absorbent resin composite assembly is produced by the method according to any one of claims 1 to 3.   A water absorbent resin sheet obtained by molding the water absorbent resin composite aggregate according to any one of claims 4 to 6 into a sheet shape.   8. The water absorbent resin composite aggregate according to claim 7, wherein the fiber is not bonded and / or embedded in the water absorbent resin particles, and the water absorbent resin particles are not bonded and / or embedded in the fibers. Alternatively, a water-absorbent resin sheet obtained by forming both into a sheet.   The water absorbent resin sheet according to claim 8, wherein the content of the water absorbent resin composite aggregate is 50% by weight or more.   A water absorbent article comprising the water absorbent resin sheet according to any one of claims 7 to 9.

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