JP2000301644A - Water absorbent articles - Google Patents

Abstract

(57) [Problem] To provide a water-absorbent article having a high water-absorption rate, a large amount of water absorption, and excellent fixability of a swollen gel after absorbing water. SOLUTION: This is a water-absorbing article comprising a water-absorbing material in which water-absorbing polymer particles are immobilized on one surface of a fibrous base material, wherein the water-absorbing polymer particles absorb an aqueous liquid through the fibrous base material. A water-absorbent article wherein the absorbent is produced through a step of adhering the water-absorbing polymer particles undergoing polymerization in a gas phase to one surface of a fibrous base material.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a water-absorbing article, and more particularly to a water-absorbing article which has a high absorption rate of an aqueous liquid and hardly releases the absorbed aqueous liquid even when pressure is applied. The water-absorbing article of the present invention is particularly suitable for use as a disposable diaper, but is also suitable for various uses in which a water-absorbing material such as a sanitary napkin is used.

[0002]

2. Description of the Related Art Water-absorbing articles using water-absorbing polymer particles as a material for absorbing an aqueous liquid are widely used as so-called disposable diapers and sanitary napkins. Conventional water-absorbing articles are mainly used as a water-absorbing material for absorbing an aqueous liquid by dispersing water-absorbing polymer particles in a fibrous base material such as pulp or absorbing water between two sheet-like fibrous base materials. A material in which conductive polymer particles are interposed is used. Disposable diapers and sanitary napkins distributed on the market mainly use this water-absorbing material to improve mechanical strength, water leakage prevention, dispersion permeability of aqueous liquid to be absorbed, and feel during use. , Polyolefin sheet, paper, pulp, non-woven fabric and the like are appropriately laminated.

[0003]

One of the problems of such conventional water-absorbent articles is that the water-absorbent polymer particles are only mechanically engaged with and held by the fibrous base material. The reason is that the water-absorbing polymer particles move during the process and during use, and the polymer particles tend to be offset in the water-absorbing material. As a solution to this problem, there is a method of bonding the fibrous base material and the water-absorbing polymer particles with an adhesive, but this method tends to inhibit the water-absorbing polymer particles from absorbing and swelling the aqueous liquid. Yes, does not give satisfactory water absorbent articles. In addition, the water-absorbent article is required to absorb the aqueous liquid to be absorbed quickly when it comes into contact with the liquid, and not to easily release the absorbed liquid even when pressure is applied. Are not yet satisfactory in these properties.

[0004] Accordingly, the present invention seeks to provide a water absorbent article improved in these respects. Specifically, an object of the present invention is to provide a water-absorbing article having a high water-absorbing rate, a large amount of water absorption, and excellent fixability of a swollen gel after absorbing water.

[0005]

Means for Solving the Problems The present inventors have made intensive studies to solve the above-mentioned problems, and as a result, have found that the following effects can be obtained according to the present invention. . The present invention relates to a water-absorbent article comprising a water-absorbing material in which water-absorbing polymer particles are immobilized on one surface of a fibrous base material, wherein the water-absorbing polymer particles absorb an aqueous liquid through the fibrous base material. Thus, the present invention provides a water-absorbent article produced by a process in which the absorbent absorbs the water-absorbing polymer particles that are undergoing polymerization in a gas phase on one surface of a fibrous base material.

[0006] In a preferred embodiment of the water-absorbent article of the present invention, at least a part of the water-absorbent polymer particles constitutes an aggregated particle in which primary particles are bonded to each other; An embodiment in which 30% by weight or more constitutes the aggregated granules; an embodiment in which some of the primary particles constituting the aggregated granules do not adhere to the fibrous base material; 50-1000 μm
The average particle diameter of the aggregated granular material is 100 to 3
000 μm.

Further, the present invention provides a water-absorbing material in which water-absorbing polymer particles are immobilized on one surface of a fibrous base material, wherein the water-absorbing polymer particles are configured to absorb an aqueous liquid through the fibrous base material. An absorbent article, wherein at least a part of the water-absorbing polymer particles has an average particle diameter of 50 to 1000 μm.
And 30% by weight or more of the primary particles form an aggregated granular material having a shape satisfying the following conditions, wherein the particles are bonded to each other while substantially maintaining the particle shape, and The present invention also provides a water-absorbent article in which some of the constituent particles of the agglomerated particles do not adhere to the fibrous base material. Average particle diameter (D) 100 ≦ D ≦ 3000 μm Declination (θ) by declination analysis 10 ≦ θ ≦ 25 5 Hz / 20 Hz intensity ratio of frequency analysis (k) 0.6 ≦ k ≦ 0.9 Ratio of long diameter (L) to shortest diameter (l) 1.2 ≦ L / l ≦ 15.0

In a preferred embodiment of the water-absorbent article of the present invention, the fibrous base material is in a sheet form; the fibrous base material is selected from synthetic fibers, natural fibers, semi-synthetic fibers and inorganic fibers. An embodiment comprising one or two or more types; an embodiment in which the fibrous base material is a nonwoven fabric, in particular, a nonwoven fabric formed of fibers having a diameter of 10 to 50 μm;
0 to 100 g / m ² ; 50% by weight or more, particularly 80% by weight or more of the water-absorbing polymer particles constitute the agglomerated particles; and the surface of the water-absorbing polymer particles is crosslinked. An embodiment in which the water-absorbing polymer particles are fixed at 50 to 300 g / m ² on the fibrous base material; and a layer made of fluff pulp is laminated on the water-absorbing polymer particle side of the water-absorbing material. A mode in which fluff pulp layers are laminated on both surfaces of the water-absorbing material, and the basis weight of the fluff pulp layer laminated on the water-absorbing polymer particle side is laminated on the fibrous base material side. An embodiment in which the basis weight of the fluff pulp layer is larger than the basis weight of the fluff pulp layer laminated on the water absorbing polymer particle side of the water absorbing material.
0 g / m ² .

The water-absorbing material used in the present invention forms droplets of a reaction mixture in which a polymerization is initiated by mixing an aqueous solution of a polymerizable monomer to give a water-absorbing polymer and a redox polymerization initiator in a gas phase. The droplets are bound together in the gas phase and / or on the fibrous base material while maintaining their shapes substantially, to form aggregated granules, and the aggregated granules formed in the gas phase are mixed with the fibrous base material. After being supported on the material, it is preferable that the polymer is produced by completing the polymerization of the aggregated granular material on the fibrous base material and fixing the aggregated granular material to the fibrous base material.

[0010] In a preferred embodiment of the production method,
An embodiment in which the polymerization rate of the polymerizable monomer at the time of contact with the fibrous base material is 20 to 97%; a droplet of the reaction mixture is mixed with an oxidizing agent constituting a redox-based polymerization initiator and a polymerizable monomer-water solution. And a second liquid containing an aqueous solution of a polymerizable monomer and a reducing agent that constitutes a redox-based polymerization initiator, which are formed by mixing in a gaseous phase; Wherein the polymerizable monomer is mainly composed of an aliphatic unsaturated carboxylic acid or a salt thereof; and wherein the polymerizable monomer is a carboxyl group. Wherein the main component is acrylic acid in which at least 20 mol% of the acid is neutralized with an alkali metal salt or an ammonium salt; the oxidizing agent constituting the redox polymerization initiator is hydrogen peroxide, and the reducing agent is L- Ass Can be exemplified embodiment is Rubin acid or L- ascorbic acid alkali metal salts.
In this specification, “to” indicates a range including numerical values described before and after it as a minimum value and a maximum value.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the water-absorbent article of the present invention will be described in detail with reference to preferred embodiments.

The water-absorbing material constituting the water-absorbing article of the present invention is a material in which water-absorbing polymer particles are fixed to one surface of a fibrous base material (hereinafter sometimes abbreviated as “base material”). . The water absorbing material is
It satisfies at least one of the following conditions. (1) It is manufactured through a step of adhering water-absorbing polymer particles that are undergoing polymerization in the gas phase to one surface of a fibrous base material. (2) At least a part of the water-absorbing polymer particles is composed of primary particles having an average particle diameter of 50 to 1000 μm, and 30% by weight or more of the primary particles are bonded to each other while substantially maintaining the particle shape. Agglomerated granules having a shape satisfying the following conditions are formed, and some of the constituent particles of the agglomerated granules do not adhere to the fibrous base material. Average particle diameter (D) 100 ≦ D ≦ 3000 μm Declination (θ) by declination analysis 10 ≦ θ ≦ 25 5 Hz / 20 Hz intensity ratio of frequency analysis (k) 0.6 ≦ k ≦ 0.9 Ratio of long diameter (L) to shortest diameter (l) 1.2 ≦ L / l ≦ 15.0

It is preferable that at least a part of the water-absorbing polymer particles used in the present invention is composed of primary particles having an average particle diameter of 50 to 1000 μm. The average particle diameter of the primary particles is more preferably 100 to 900 μm, and 200 to 900 μm.
800 μm is particularly preferred.

At least 30% by weight of the primary particles are preferably such that the particles are bonded to each other to form an aggregated granular material while substantially maintaining the particle shape. The primary particles constituting the aggregated granules are more preferably at least 50% by weight, particularly preferably at least 80% by weight. Some of the primary particles constituting the aggregated granular material do not adhere to the fibrous base material. That is, the agglomerated particles are composed of primary particles directly attached to the fibrous base material and primary particles not attached to the fibrous base material at all. Since such agglomerated particles have a large specific surface area, the water absorption rate is high, and only a part of the primary particles constituting the agglomerated particles are bound to the fibrous base material. It is less constrained by the porous substrate and has excellent water absorption capacity. In addition, since the bonding surfaces of the primary particles constituting the aggregated granular material are integrated, the aggregated granular material may be broken down into primary particles and fall off from the fibrous base material not only before water absorption but also after water absorption. Less is.

The aggregated granular material has an average particle diameter (D),
Declination (θ) by declination analysis, 5 Hz / 20 of frequency analysis
It is preferable that the Hz intensity ratio (k) and the ratio between the longest diameter (L) and the shortest diameter (l) of the aggregated granules are within the specific ranges defined above. The average particle diameter (D) of the aggregated granular material is 100
3,000 μm, preferably 200-200 μm.
0 μm is more preferable, and 250 to 2000 μm is particularly preferable. If the average particle size is smaller than 100 μm, the water absorption performance tends not to be sufficiently exhibited. Further, when the average particle diameter is 3
If it is larger than 000 μm, the adhesive strength to the fibrous base material tends to be weak.

The argument (θ) obtained by the argument analysis is 10 to 25.
Is preferable, 12 to 24 are more preferable, and 1
4 to 22 are particularly preferred. 5Hz / 20H for frequency analysis
The z intensity ratio (k) is preferably 0.6 to 0.9, more preferably 0.65 to 0.85, and 0.65 to 0.85.
0.80 is particularly preferred. The ratio between the longest diameter (L) and the shortest diameter (l) of the aggregated granules is preferably 1.2 to 15.0, more preferably 1.5 to 10.0, and 1.5 to 8.0.
0 is particularly preferred. These average particle diameter (D), declination (θ) by declination analysis, 5 Hz / 20 Hz intensity ratio (k) of frequency analysis, longest diameter (L) and shortest diameter (l) of aggregated granular material
Can be determined by a method described in Test Examples described later.

The water-absorbing material satisfying the above condition (2) can maintain a soft feeling without being angular because the polymer particles whose primary particles are truly spherical are bound together and the secondary particles are in a grape shape. Has features. As in the present invention, a water-absorbing material in which a water-absorbing polymer is immobilized on a fibrous base material has been developed as described in JP-A-9-67403. The water-absorbent resin is a resin in which angular irregular single particles adhere to fibers. For this reason, the feel to the skin is rough or tingling, and the soft feeling may be lacking. However, the water-absorbing material used in the present invention significantly improves the feel to the skin.

The water-absorbing polymer particles usually contain 50
Is preferably contained such that the ^{~300g / m 2, 100~250g / m} 2, in particular 130～220G /
More preferably, it is contained so as to be m ² . When the content of the water-absorbing polymer particles is small, the water-absorbing ability tends to be small. Further, if the content is too large, it is uneconomical, and the ratio of the primary particles that bind to the fibrous base material decreases, and the binding force with the base material tends to weaken.

The method for producing the water-absorbing material used in the present invention is not particularly limited. What is manufactured by any method is included in the scope of the present invention as long as it satisfies the above condition (1) or (2). Further, the material of the water-absorbing polymer particles and the fibrous base material constituting the water-absorbing material is not particularly limited. Therefore, conventionally known water-absorbing polymers and fibrous base materials can be used. Further, a plurality of types may be used in combination. Specific examples of the water-absorbing polymer and the fibrous base material will be described later.

A method for producing a water-absorbing material The water-absorbing material for the purpose of the present invention can be produced simply and at low cost. A preferred production method is to form droplets of a reaction mixture in which polymerization has been initiated by mixing an aqueous solution of a polymerizable monomer that gives a water-absorbing polymer and a redox polymerization initiator in a gas phase, Or, on the fibrous base material, the droplets are bound to each other while maintaining their shapes to form aggregated granules, and after the aggregated granules formed in the gas phase are supported on the fibrous base material, The polymerization of the aggregated granular material is completed on the fibrous base material, and the aggregated granular material is immobilized on the fibrous base material.

<Polymerizable Monomer> The type of polymerizable monomer used is not particularly limited as long as it provides a water-absorbing polymer and as long as its polymerization is initiated by a redox initiator. . The monomer must be water-soluble because it is used as an aqueous solution, but the monomer that provides the water-absorbing polymer is generally water-soluble.

A representative example of such a monomer, which is also preferable 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, and unsaturated dicarboxylic acids or salts thereof such as maleic acid or salts thereof, itaconic acid or salts thereof. These may be used alone or as a mixture of two or more. Among them, preferred are acrylic acid or a salt thereof, and methacrylic acid or a salt thereof, and particularly preferred is acrylic acid or a salt thereof.

As the polymerizable monomer for providing the water-absorbing polymer used in the present invention, an aliphatic unsaturated carboxylic acid or a salt thereof is preferable as described above.
As the aqueous solution of (1), an aqueous solution containing an aliphatic unsaturated carboxylic acid or a salt thereof as a main component is preferable. here,
The phrase "having an aliphatic unsaturated carboxylic acid or a salt thereof as a main component" means that the aliphatic unsaturated carboxylic acid or a salt thereof is contained in an amount of 50 mol% or more, preferably 80 mol% or more, based on the total amount of the polymerizable monomer. Means that

As the salt of the aliphatic unsaturated carboxylic acid, a water-soluble salt, for example, an alkali metal salt, an alkaline earth metal salt, an ammonium salt and the like are usually used. The degree of neutralization is appropriately determined according to the purpose. In the case of acrylic acid, it is preferable that 20 to 90 mol% of the carboxyl group is neutralized with an alkali metal salt or an ammonium salt. The degree of partial neutralization of acrylic acid monomer is 20 mol%
If it is less than 3, the water-absorbing ability of the produced water-absorbing polymer tends to be remarkably reduced. For neutralization of the acrylic acid monomer, an alkali metal hydroxide, bicarbonate or the like or ammonium hydroxide can be used, but an alkali metal hydroxide is preferable, and a specific example thereof is water. Sodium oxide and potassium hydroxide.

In the present invention, in addition to the above-mentioned aliphatic unsaturated carboxylic acids, polymerizable monomers copolymerizable therewith, such as (meth) acrylamide and (poly) ethylene glycol (meth) acrylate , 2-hydroxyethyl (meth) acrylate, or a low water-soluble monomer
However, alkyl acrylates such as methyl acrylate and ethyl acrylate may be copolymerized in an amount that does not decrease the performance of the resulting water-absorbing polymer. In this specification, the term “(meth) acryl” shall mean both “acryl” and “methacryl”.

Among these polymerizable monomers, the one that gives a water-absorbing polymer is not used as an auxiliary component for an aliphatic unsaturated carboxylic acid or a salt thereof, but is an aqueous solution of a polymerizable monomer that gives a water-absorbing polymer. ] Can be used as the main monomer.

An aliphatic unsaturated carboxylic acid or a salt thereof, particularly acrylic acid or a salt thereof, may form a self-cross-linked polymer by itself, but a cross-linking agent is used in combination to positively form a cross-linked structure. You can also. When a cross-linking agent is used in combination, the water-absorbing performance of the resulting water-absorbing polymer is generally improved. Examples of the crosslinking agent include divinyl compounds copolymerizable with the polymerizable monomer, for example, N, N′-methylenebis (meth) acrylamide, (poly) ethylene glycol (meth) acrylates, and carboxylic acids. A water-soluble compound having two or more functional groups capable of reacting with water, for example, polyglycidyl ethers 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 to be used is 0.001 to 1% by weight, preferably 0.01 to 1% by weight, based on the charged amount of the monomer.
0.5% by weight.

The concentration of the polymerizable monomer in the aqueous polymerizable monomer 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. If the concentration is less than 20% by weight, it is difficult to form droplets having an appropriate viscosity, and furthermore, it is not preferable because the water absorbing ability of the water-absorbing polymer after polymerization cannot be sufficiently obtained. The upper limit is preferably about 80% by weight from the viewpoint of handling the polymerization reaction solution.

<Redox-based polymerization initiator> The polymerization initiator used in the present invention is a redox-based one obtained by combining an oxidizing radical generator and a reducing agent, and exhibits a certain degree of water solubility. Must.
Examples of such an oxidizing agent include hydrogen peroxide, persulfates such as ammonium persulfate and potassium persulfate, peroxides such as hydroperoxides such as t-butyl hydroperoxide and cumene hydroperoxide, and others. , Ceric salts, permanganates, chlorites, hypochlorites, etc., of which hydrogen peroxide is particularly preferred. The amount of the oxidizing agent to be 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 above-mentioned oxidizing agent. Specific examples thereof include sulfites such as sodium sulfite and sodium hydrogen sulfite, sodium thiosulfate, cobalt acetate, copper sulfate, and ferrous sulfate. , L-ascorbic acid or alkali metal salts of L-ascorbic acid. Among them, L-ascorbic acid or L-ascorbic acid alkali metal salt is particularly preferred. The amount of these reducing agents used is 0.1 to the polymerizable monomer.
001 to 10% by weight, preferably 0.01 to 2% by weight.

<Polymerization method> In a preferred production method, an aqueous solution of a polymerizable monomer which gives a water-absorbing polymer,
Specifically, a redox-based polymerization initiator is disposed in an aqueous solution of a polymerizable monomer containing an aliphatic unsaturated carboxylic acid or a salt thereof as a main component, and polymerization of the monomer is started. And forming the reaction mixture containing the produced polymer during polymerization into droplets in the gas phase and binding the droplets together in the gas phase and / or on the fibrous base material to form aggregated granules, The granules complete their polymerization on the fibrous substrate. Therefore, after the aggregated granules formed in the gas phase are supported on the fibrous base material (in some cases, the fibrous base material on which the aggregated granules are supported), the aggregated granules on the fibrous base material The body completes the polymerization as it is. In this specification, "on the fibrous base material" means on the surface of the formed fibrous base material,
It also covers on the base fiber and on the inner surface of the void between the fibers constituting the base.

In such a polymerization system, a monomer is used.
When the redox system is formed in the coexistence, polymerization is started practically immediately, and the time until the polymerization by the redox initiator reaches a predetermined polymerization rate corresponding to the chain polymerization, that is, the monomer-containing aqueous solution It is necessary to sufficiently consider that the time required for the viscosity to reach the predetermined level is relatively short, and the monomer-containing aqueous solution after the initiation of the polymerization forms droplets of the predetermined viscosity, and forms aggregated particles and forms It is necessary to select operating conditions so as to produce strong adhesion.

Under such considerations, one preferred method is to use a first liquid comprising a polymerizable monomer-water solution containing one of an oxidizing agent and a reducing agent constituting a redox polymerization initiator and a redox polymerization initiator. Initiating the polymerization by mixing the second and, if desired, a second liquid comprising an aqueous solution containing a polymerizable monomer in the gas phase.

As a specific means, for example, the intersection angle between the liquids flowing out of the first liquid and the second liquid from the nozzle is one.
There is a method of jetting from separate nozzles so as to collide at an angle of 5 degrees or more and in a liquid column state. In this way, by making the two liquids have an intersection angle and collide with each other, a part of the outflow energy from the nozzle is used for mixing. The intersection angle between the first liquid and the second liquid flowing out of each nozzle is determined by the properties of the polymerizable monomer used,
Select as appropriate according to the flow rate ratio and the like. For example, if the linear velocity of the liquid is high, the intersection angle can be reduced. To obtain a sufficient mixing effect, 15 degrees or more is required, and a particularly preferable angle is 20 degrees or more. As long as a liquid column is formed after the collision between the first liquid and the second liquid (details will be described later), the upper limit of the angle is not particularly limited, but is 120 ° or less, particularly preferably 100 ° or less for an industrial apparatus.

In this method, it is necessary to collide in a liquid column state so that the two liquids, the first liquid and the second liquid, coming out of the respective nozzles merge to form a liquid column. By colliding in the liquid column state in this way, liquids can be mixed at a set flow rate ratio, and the polymerization reaction is favorably performed. If the first liquid and the second liquid collide after becoming particulate, the mixing ratio is different from the set flow rate ratio, and a favorable result is hardly obtained. Further, the distance between the nozzle tips can be set freely within a range where the fluid can collide in a liquid column state, and the tips of the nozzles may be in contact. The inner diameter of the nozzle may be appropriately selected depending on the properties of the polymerizable monomer to be used and the shape of the intended water-absorbing material, but is preferably 0.15 to 2.0.
mm, more preferably 0.1 to 1.0 mm.

In this case, the temperature of the first liquid is usually from room temperature to about 60 ° C., preferably from room temperature to about 40 ° C.
The temperature of the second liquid is also usually from room temperature to about 60 ° C, preferably from room temperature to about 40 ° C. As described above, the respective aqueous solutions ejected from the nozzles collide in a liquid column state to combine the two liquids. After the merging, a liquid column is formed, and this state is maintained for a certain period of time. Thereafter, the liquid column is disassembled into a droplet. The resulting droplets fall in the gas phase or onto the substrate, where they form aggregated particulates.

The time for forming and holding the liquid column after the coalescence, the length of the liquid column, and the size of the droplets vary depending on the setting conditions such as the inner diameter of the nozzle, but generally the holding time is 0.1 to 3 seconds and the length of the liquid column is The size is 3 to 50 mm and the size of the droplet is about 5 to 300 in diameter.
0 μm. In order for the polymerization of the droplets to proceed and bind to each other to form appropriate aggregated granules, the size of the droplets is particularly 5
It is preferable to set it in the range of 0 to 1000 μm.

As a gas in the gaseous phase which provides a place for starting the polymerization and forming droplets during the polymerization, nitrogen, helium, carbon dioxide and the like which are inert to the polymerization are preferable. Good. Also, the humidity in the gas is not particularly limited, including the case of only water vapor.However, if the humidity is too low, the water in the aqueous solution of the monomer evaporates before the polymerization proceeds, and the monomer is precipitated. There is a possibility that the polymerization rate is remarkably reduced or the polymerization is stopped halfway. The temperature condition of the gas is from room temperature to 150 ° C., preferably 1
It is below 00 ° C. The flow direction of the gas may be either countercurrent or cocurrent with respect to the direction of travel of the liquid column and the droplet, but when it is necessary to extend the residence time of the droplet in the gas phase, that is, the polymerization rate of the polymerizable monomer is reduced. If it is necessary to raise the viscosity of the liquid droplets, and thus increase the viscosity of the liquid droplets, countercurrent (anti-gravity direction) is better.

The droplets undergoing polymerization collide with each other and adhere to each other in the gas phase or on the fibrous base material while maintaining their shapes substantially to form aggregated granules. The above aggregated granules are left as is, and the aggregated granules formed in the gas phase are supported on a fibrous base material, and then the polymerization is completed on the base material. Is immobilized on the fibrous base material by surrounding or in contact with the base fiber. At least a portion of the constituent particles of the aggregated granules fixed to the fibrous base material constitute aggregated granules joined to each other while substantially maintaining the particle shape, and the constituent particles of the aggregated granules are Some have a structure that does not adhere to the fibrous base material.

The polymerization rate at the time when the droplets during the polymerization are in contact with the gas phase or on the substrate to form the aggregated particles is 20 to 20.
97%, preferably 30-97%, more preferably 5%
Various conditions are set so as to be 0 to 95%. If the polymerization rate is too low, even if the droplets collide with each other in the gas phase, they will not form aggregated granules but will be integrated into large particles, or the liquid will fall when the droplets fall onto the substrate. It becomes impossible to adhere to the base material in the form of agglomerated granules by spreading or being absorbed or impregnated on the base material. On the other hand, if it is too high, the adhesive strength to the base material does not appear, and the base material and the water-absorbing polymer
And the fixability becomes worse.

The polymerization rate and the formation of agglomerated particles are determined by the angle of intersection between the first liquid and the second liquid flowing out of the nozzle, the diameter of the nozzle,
Depending on the type and amount of the polymerization initiator, the distance between the nozzle and the substrate, the temperature and humidity of the gas phase, the number and arrangement of the nozzles, and the relative position or distance between the nozzle and the substrate, the probability of collision between the liquids can be increased, It is possible to control by controlling the degree of polymerization progress in the phase. A method other than using two opposing nozzles is also possible. As an example of such a case, a binding type nozzle in which the tip positions of the two nozzles are aligned,
One example is a double nozzle in which one nozzle is inserted into the other nozzle.

The components of each liquid ejected from the nozzle collide and mix in a liquid column state to form droplets, and the droplets are polymerized while falling on the substrate or as the polymerization proceeds on the substrate to form aggregated granular materials. And the final stage of polymerization proceeds on the substrate.

If necessary, the remaining monomer may be treated in order to react the unreacted monomer remaining in the aggregated granules. Examples of the method of treating the remaining monomer include 1) a method of promoting polymerization of the monomer, 2) a method of leading the monomer to another derivative, and 3) a method of removing the monomer.

Examples of the method of promoting the polymerization of the monomer 1) include a method of further heating the composite of the aggregated granular material and the base material, and adding a catalyst or a catalyst component to the aggregated granular material to promote the polymerization of the monomer. Examples of the method include a method of heating later, a method of irradiating ultraviolet rays, and a method of irradiating electromagnetic radiation or particulate ionizing radiation. The method of further heating the composite of the aggregated granular material and the substrate is a method of heating the composite of the aggregated granular material and the substrate at 100 to 250 ° C. to polymerize the monomer remaining in the aggregated granular material. .

A method of adding a catalyst or a catalyst component for accelerating the polymerization of a monomer to the aggregated particles is, for example, that when a polymerization is carried out using a redox polymerization initiator, the radical generator remains. Since the amount is large, a reducing agent solution may be applied to the aggregated granules. As the reducing agent, sodium sulfite, sodium hydrogen sulfite, L-ascorbic acid, or the like used as a redox-based initiator may be used, and these are usually applied to the aggregated granules as a 0.5 to 5% by weight aqueous solution. The amount of the reducing agent applied may be 0.1 to 2% by weight based on the dry resin. The application of the reducing agent solution can be performed by an arbitrary method such as spraying using a sprayer or dipping in the reducing agent solution. The aggregated particles to which the reducing agent has been added are then heated to polymerize the polymerizable monomer. Heating may be performed, for example, at 100 to 150 ° C. for about 10 to 30 minutes. This heating reduces the water content of the aggregated granules, but if the water content is high, it is further dried by a dryer to obtain a water-absorbing material for the product.

In the method of irradiating the composite of the agglomerated granular material and the base material with ultraviolet light, an ordinary ultraviolet lamp may be used.
The irradiation intensity, irradiation time and the like vary depending on the type of the fibrous substrate used, the amount of the residual monomer impregnated, and the like, but are generally from 10 to 200 w / cm, preferably from 30 to 12 UV lamps.
0 w / cm, irradiation time 0.1 second to 30 minutes, lamp-composite interval 2 to 30 cm. The amount of water in the composite at this time is generally 0.01 to 40 parts by weight, preferably 0.1 to 1.0 part by weight, per 1 part by weight of the polymer. A water content of less than 0.01 part by weight or more than 40 parts by weight is not preferable because it has a significant effect on the reduction of the residual monomer. As an atmosphere for irradiating ultraviolet rays, any of a vacuum, in the presence of an inorganic gas such as nitrogen, argon, and helium, or in air can be used. The irradiation temperature is not particularly limited, and the object can be sufficiently achieved at room temperature. There is no particular limitation on the ultraviolet irradiation apparatus to be used, and any method such as a method of irradiating for a fixed time in a stationary state or a method of continuously irradiating with a belt conveyor can be used.

As a method of irradiating the composite of the aggregated granular material and the substrate with radiation, high-energy radiation such as accelerated electrons or gamma rays is used. The dose to be applied varies depending on the amount of residual monomer in the composite, the amount of water, etc.,
Generally, 0.01 to 100 megarads, preferably 0.1 to 100 megarads.
1 to 50 megarads. At a dose exceeding 100 megarads, the water absorption becomes extremely small, and when it is less than 0.01 megarads, the water absorption capacity and water absorption rate aimed at by the present invention are large,
It is difficult to obtain a particularly small residual monomer. Also,
At this time, the amount of water in the composite is generally 40 parts by weight or less, preferably 10 parts by weight with respect to 1 part by weight of the fibrous substrate.
Parts by weight or less are employed. If the amount of water exceeds 40 parts by weight, the effect of improving the water absorption rate is small, and in particular, the amount of unpolymerized monomer is significantly affected, which is not preferable. As the atmosphere when irradiating the composite with high-energy radiation,
It can be used under vacuum, in the presence of an inorganic gas such as nitrogen, argon, helium, or in air. The preferred atmosphere is air. Irradiation in the air increases the water absorption capacity and water absorption rate and reduces the residual monomer in particular. The irradiation concentration is not particularly limited, and the object can be sufficiently achieved at room temperature.

Examples of the method of introducing the monomer into the other derivative of 2) 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.

As a method for removing the monomer in 3),
For example, a method of extracting and distilling with an organic solvent may be mentioned. In the method of extracting with an organic solvent, the complex of the aggregated granular material and the substrate is immersed in a water-containing organic solvent to extract and remove the remaining monomer. Ethanol, methanol, acetone and the like can be used as the water-containing organic solvent, and the water content thereof is preferably from 10 to 99% by weight, particularly preferably from 30 to 60% by weight. In general, the higher the water content, the higher the ability to remove residual monomers. However, when a water-containing organic solvent having a high water content is used, energy consumption in the subsequent drying step increases. The time for immersing the composite of the aggregated granular material and the base material in the aqueous organic solvent is usually sufficient for about 5 to 30 minutes, and the extraction of the residual monomer such as shaking the composite of the aggregated granular material and the base material is sufficient. It is also preferable to employ means for promoting. After the immersion treatment, it is usually treated by a dryer and dried.

As a method for distilling off the monomer,
The composite of the aggregated particles and the substrate is treated with superheated steam or a steam-containing gas. For example, saturated steam of 110 ° C.
By heating to 20 to 150 [deg.] C. and bringing it as superheated steam into contact with the composite of the aggregated granular material and the base material, the residual monomer in the aggregated granular material can be reduced. In this method, it is considered that when water in the aggregated granules evaporates as water vapor, the remaining monomer is also vaporized and escapes from the aggregated granules. According to this method, both the removal of the residual monomer and the drying of the product can be performed.

Further, the surface of the aggregated particles on the substrate can be cross-linked with a cross-linking agent for the purpose of improving the water absorption performance. In general, it is known to improve the properties of resin particles by applying a crosslinking agent to the surface of powdery water-absorbing polymer particles and then heating and crosslinking the surface to form a crosslinked structure selectively on the surface. As a result, when swelling by absorbing water, it is considered that the shape can be maintained without inhibiting swelling. In this step, first, a solution of the surface cross-linking agent is applied to the aggregated granules of the composite of the aggregated granules and the substrate. Examples of the surface crosslinking agent include polyfunctional compounds copolymerizable with polymerizable monomers such as N, N'-methylenebis (meth) acrylamide, (poly) ethylene glycol bis (meth) acrylate, and (poly) ethylene glycol diglycidyl ether. A compound having a plurality of functional groups capable of reacting with the carboxylic acid group of the above is used. These surface cross-linking agents are generally used in an amount of 0.1 to the aggregated granules (dry basis).
It is used in an amount of 1 to 1% by weight, preferably 0.2 to 0.5% by weight. These surface cross-linking agents are diluted with water, ethanol, methanol or the like to 0.1 to 1% by weight, particularly 0.2 to 0.5% by weight, so as to be uniformly applied to the entire surface of the aggregated granular material. % Solution is preferred. The application of the cross-linking agent solution is usually performed by spraying the cross-linking agent solution onto the aggregated granules using a sprayer, or inverting the composite of the aggregated granules and the base material so that the resin particle adhesion surface is on the lower surface. It is preferable to apply the method by applying the crosslinking agent solution with a roll brush whose lower part is immersed in a tank containing the crosslinking agent solution. After the crosslinker solution is applied in excess, the excess crosslinker solution may be removed by squeezing the resin particles lightly with a squeeze roll or blowing air to such an extent that the resin particles are not crushed. The application of the crosslinking agent solution may be performed at room temperature. The composite of the aggregated granular material and the substrate to which the crosslinking agent solution has been applied is then heated to cause a crosslinking reaction to proceed, thereby selectively forming a crosslinked structure on the surface of the aggregated granular material. The conditions for the cross-linking reaction may be appropriately selected depending on the cross-linking agent to be used, but the reaction is usually performed at a temperature of 100 ° C. or higher for 10 minutes or longer.

The water absorbing material manufactured by the above manufacturing method is
It is excellent in water absorption, has a high water absorption rate, and most of the superabsorbent polymer is fixed on the fibrous base material with good stability, and also has excellent fixability of the swollen gel after absorbing water. Japanese Patent Application Laid-Open No. 9-239912, which is a prior art related to the present invention.
In the publication, water-soluble ethylenically unsaturated monomer-impregnated water-absorbing polymer particles are placed on or in a fibrous substrate, and then the ethylenically unsaturated monomer in the water-absorbing polymer particles is polymerized. Further, there is disclosed a method for producing a water-absorbing material, comprising immobilizing water-absorbing polymer particles on or in the fibrous base material. Since this method uses the water-absorbent resin polymer particles which have been polymerized in advance, the bonding with the fibers of the fibrous base material is performed by point bonding with the surface of the primary particles constituting the aggregated granular material. On the other hand, since the present invention binds to the fibers of the fibrous base material before the polymerization is not completed, the fibers of the fibrous base material penetrate through some of the primary particles constituting the aggregated granular material. When comparing JP-A-9-239912 and the water-absorbing resin of the above-mentioned water-absorbing material, the adhesive strength at the time of water absorption of the above-mentioned water-absorbing material is greatly improved as is clear from the bonding mechanism.

<Fibrous Substrate> As the fibrous substrate on which the droplets or agglomerated particles of the above-mentioned reaction mixture undergoing polymerization are to be adhered, synthetic fibers, natural fibers, semi-synthetic fibers, inorganic fibers and the like are used. be able to. Among them, a formed fibrous base material is preferable. The term "fibrous base material" used herein refers to a pad formed by loosely forming fibers, a carded or air-layed web, or a tissue paper.
Woven fabrics such as pars, cotton gauze, melias or non-woven fabrics having a specific shape. Molded fibrous base material means that cutting, joining, shaping, etc. may be necessary in order to incorporate the fibrous base material into the product, but there is no need to further perform web forming work. I do.

The fibers constituting the substrate are preferably hydrophilic fibers such as wood pulp, rayon, cotton, regenerated cellulose and other cellulose-based fibers, since they are used for water-absorbent articles. In addition, a material which enjoys the best of the present invention and which contains such a hydrophilic fiber as a main component is a particularly preferable substrate in the present invention. In addition, it is also preferable to use a fibrous base material mainly composed of polyester fibers, and other types of non-hydrophilic fibers such as polyethylene, polypropylene, polystyrene, polyamide, and polyvinyl alcohol. -System
It is also possible to use a fibrous base material mainly composed of polyvinyl chloride, polyvinylidene chloride, polyacrylonitrile, polyurea, polyurethane, polyfluoroethylene, and polyvinylidene cyanide fibers. Also, a relatively dense fibrous base material can be used as the fibrous base material. Specific examples include paper, wood, backskin, and leather.

Particularly preferred as the fibrous equipment used in the present invention is a nonwoven fabric made of fibers having a diameter of 10 to 50 μm, preferably having a basis weight of 10 to 100 g / m ² , more preferably 20 to 50 g / m ^2. Is more preferable.

<Manufacture of Water Absorbing Material> An example of an actual method for manufacturing a water absorbing material is as follows. That is, while transferring the sheet of the fibrous base material by a belt conveyor, the liquid column of the reaction mixture during the polymerization in which the polymerization of the polymerizable monomer aqueous solution has been started is dropped from above, and the generated liquid is dropped. After a predetermined period of time has passed after the aggregated granular material in which the droplets are bound together in the gas phase or on the fibrous base material sheet and supported on the base material sheet, the polymerization is completed. Since the produced water-absorbing polymer contains water, it is subjected to a drying treatment for removing water to obtain a raw material of the water-absorbing material. This is cut into a predetermined shape and size to produce a product as a water absorbing material.

In addition, JP-A-5-132502, JP-A-5-132503, and JP-A-6-211
904, JP-A-9-67403, JP-A-9-67403
-255704 and JP-A-9-286864 can be appropriately adopted.

<Water-absorbing material> The water-absorbing material obtained in this manner is such that the water-absorbing polymer becomes agglomerated granules, and at least a part of the agglomerated granules surrounds the periphery of the base fiber or is formed on the base fiber. It is fixed to the fibrous base material in contact therewith, and penetrates through some of the constituent primary particles to be carried on the base material. Therefore, the polymer is firmly fixed to the fibrous base material not only before the water absorption but also after the water absorption and the gel state, and the agglomerated granular material is further composed of the aggregated primary particles. Since the bonding surfaces are integrated and have no adhesive interface, they do not easily return to single particles even after swelling by absorbing water, and have excellent shape retention as an absorber. The fact that the water-absorbing polymer is less likely to fall off after water absorption, which is a feature of the present invention, is evident from the loading rate indicating the supporting strength of the water-absorbing polymer to the fibrous base material described later.

Further, since the water-absorbing polymer becomes agglomerated and granular, and some of the constituent primary particles do not adhere to the base fiber, the polymer is less restricted by the base fiber, so that the polymer absorbs water. The swelling inhibition received from the fiber when swelling is reduced, and a water-absorbing material having excellent water-absorbing ability can be obtained.

The water-absorbing material according to the present invention has satisfactory performance in terms of water-absorbing capacity and water-absorbing rate, as is clear from the physiological saline water-absorbing capacity and absorption rate tests described in the following Examples (and Comparative Examples). Have. According to the present invention, the water absorption capacity is generally 20 (fold) or more, usually 30 (fold) or more, and often 35 (fold) or more. The water absorption rate is generally 15 g / 5 min or more, usually 20 g / 5 min or more, and often 25 g / 5 min or more.

Further, the water-absorbing material used in the present invention is satisfactory in that the amount of residual unreacted monomer is small. The residual unreacted monomer concentration is generally 500 ppm
Hereinafter, it is usually 300 ppm or less, and often 100 ppm or less.

Water-absorbing article The water-absorbing article of the present invention comprises a water-absorbing material in which water-absorbing polymer particles are immobilized on one surface of a fibrous base material, and the water-absorbing polymer particles absorbing an aqueous liquid through the fibrous base material. This is a water-absorbing article configured to perform the following. The water-absorbing article of the present invention is a water-absorbing material in which a water-absorbing polymer is immobilized only on one side of a fibrous base material as a main water-absorbing part, and fluff pulp, paper, nonwoven fabric, which is commonly used for water-absorbing articles. It is constituted by appropriately combining a polyolefin film and the like. At this time, the water-absorbing material is arranged so that the fibrous base material side becomes the water-absorbing surface.
That is, the aqueous liquid to be absorbed passes through the fibrous base material of the water absorbing material and reaches the water absorbing polymer particles. By doing so, it is possible to obtain a water-absorbent article which is quickly absorbed and hardly releases the absorbed aqueous liquid even when pressure is applied.

In water-absorbent articles, particularly so-called disposable diapers and sanitary napkins, a material giving bulkiness such as fluff pulp is used in order to enhance adaptability to the body during use. Preferably also contains a layer of a material giving bulkiness, such as fluff pulp. The fluff pulp layer is preferably arranged on the water-absorbing polymer side, and the basis weight is preferably 80 to 250 g / m ² , particularly preferably 100 to 220 g / m ² . When the fluff pulp layers are disposed on both surfaces of the water-absorbing material, it is preferable that the basis weight on the water-absorbing polymer side is larger than that on the fibrous base material side. When a fluff pulp layer with a large basis weight is arranged on the fibrous base material side, the aqueous liquid to be absorbed passes through the hydrophilic fluff pulp layer and reaches the water absorbing material, so that the water absorbing material, which is the main absorbent, is absorbed. Absorption slows down. Also, unlike the water absorbed by the water-absorbing polymer particles, the water absorbed by the fluff pulp is easily released, so that when pressure is applied to the water-absorbing article after absorbing water, the water is easily squeezed out.

<Additives> Various additives can be added to the water-absorbing polymer, water-absorbing material, or water-absorbing article in order to impart a desired function according to the intended use. Examples of these additives include stabilizers for preventing polymer decomposition and deterioration due to the liquid to be absorbed, antibacterial agents, deodorants, deodorants, fragrances, and foaming agents.

Among the stabilizers, excrement (ie, human urine,
And a stabilizer that prevents the water-absorbent resin from decomposing and deteriorating due to feces) and body fluids (body fluids such as human blood, menstrual blood, and secreted fluid).
JP-A-63-118375 discloses a method of incorporating an oxygen-containing reducing inorganic salt and / or an organic antioxidant in a polymer, and JP-A-63-153060 discloses a method of containing an oxidizing agent. JP-A-63-127754 discloses a method of incorporating an antioxidant, and JP-A-63-272349.
Japanese Patent Application Laid-open No. Sho 6 (1994) discloses a method of incorporating a sulfur-containing reducing agent.
In JP-A-3-146964, a method of containing a metal chelating agent, in JP-A-63-15266, a method of containing a radical chain inhibitor, and in JP-A-1-275661, a phosphinic acid group or a phosphonic acid group is disclosed. For containing an amine compound or its salt
No. 9257 discloses a method of containing a polyvalent metal oxide,
JP-A-2-255804, JP-A-3-17900
No. 8 proposes a method for coexisting a water-soluble chain transfer agent during polymerization. Also, JP-A-6-306202, JP-A-7-53884, and JP-A-7-622.
No. 52, JP-A-7-113048, JP-A-7-13048
JP-A-145326, JP-A-7-145263, JP-A-7-228788, JP-A-7-228
The materials and methods described in 790 can also be used. Specific examples include potassium oxalate titanate, tannic acid, titanium oxide, amine phosphinate (or a salt thereof), amine phosphonate (or a salt thereof), and metal chelate. Of these, especially human urine,
Stabilizers for human blood and menstrual blood may be called human urine stabilizers, human blood stabilizers, and menstrual blood stabilizers, respectively.

An antibacterial agent is used to prevent spoilage due to the absorbed liquid. Examples of antibacterial agents include "New Development of Sterilization and Antibacterial Technology", pp. 17-80 (Toray Research Center (1994)), "Testing and Evaluation Methods and Product Design of Antibacterial and Antifungal Agents", pp. 128-344 (NTT)・ S (19
97)), Japanese Patent No. 2760814,
179114, JP-A-56-31425,
JP-A-57-25813, JP-A-59-1898
No. 54, JP-A-59-105448, JP-A-60-158861, JP-A-61-181532
JP-A-63-135501, JP-A-63-135501
JP-139556, JP-A-63-156540, JP-A-64-5546, JP-A-64-554
7, JP-A-1-153748, JP-A-1-153748
JP-A-221242, JP-A-2-253847,
JP-A-3-59075, JP-A-3-103254
JP, JP-A-3-221141, JP-A-4-14-1
1948, JP-A-4-92664, JP-A-4-138165, JP-A-4-266947, JP-A-5-9344, JP-A-5-68694
JP, JP-A-5-161671, JP-A-5-15-1
79053, JP-A-5-269164, and JP-A-7-165981 can be appropriately selected.

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

[0068] Other preferred antibacterial reagents include bis-biguanides. The bis-biguanides are also known as antibacterial reagents. These are, for example, U.S. Pat.Nos. 2,684,924, 2,990,425,
Nos. 2,830,006 and 2,863,019. Most preferred bis-biguanides include 1,6
-Bis (4-chlorophenyl) diguanidehexane, which is known as chlorhexidine and its water-soluble salt. Particularly preferred are the hydrochloride, acetate and gluconate salts of chlorohexidine.

[0069] Several other types of antibacterial reagents are also useful. Examples include carbanilides, substituted phenols, metal compounds, and rare earth salts of surfactants. Carbanilide includes 3,4,
4'-trichlorocarbanilide (TCC, triclocarban) and 3- (trifluoromethyl-4,4'-dichlorocarbanilide (IRGASAN). Substituted phenols include 5-chloro-2- (2 , 4-dichlorophenoxy) phenol (IRGASAN DP-300) Examples of metal compounds include graphite and tin salts such as zinc chloride, zinc sulfide and tin chloride. It is disclosed in EP 10819. Rare earth salts of this type include linear C10.
And lanthanum salts of -18 alkylbenzene sulfonates.

Further, deodorants, deodorants and fragrances are used to prevent or reduce the unpleasant odor of the absorbed liquid. Deodorants, deodorants, and fragrances are described, for example, in "New Deodorants and Deodorants, Techniques and Prospects", pp. 38-20 (Toray Research Center (1994)), JP-A-59-105448, JP-A-60-1985. No. 158861, JP-A-61-1986
No. 181532, Japanese Patent Application Laid-Open No. 1-153748,
JP-A-1-221242, JP-A-1-26595
No. 6, JP-A-2-41155, JP-A-2-2-2
JP-A-53847, JP-A-3-103254, JP-A-5-269164, JP-A-5-277143
Can be selected as appropriate. Specifically, examples of deodorants and deodorants include iron complexes, tea extract components, and activated carbon. As the fragrance, for example, fragrance-based (citral, cinnamaldehyde, heliotopin, camphor, bornyl acetate) wood vinegar, paradichlorobenzene, surfactant, higher alcohol, terpene-based compound (limonene, pinene, camphor, borneol, eucalyptol, Eugenol).

A foaming agent and a foaming aid can be used in combination to make the water-absorbing polymer porous and increase the surface area for improving the water-absorbing performance of the water-absorbing polymer. Examples of the foaming agent and foaming assistant include “rubber / plastic compounding chemicals” (Rubber Digest Inc., 198).
9, pages 259-267) can be selected as appropriate. For example, sodium bicarbonate, nitroso compounds,
Examples include azo compounds and sulfonyl hydrazides.

These additives are appropriately added in each step of the production of the water-absorbing resin, the water-absorbing material, and the water-absorbing article according to the purpose and mechanism of action. For example, the foaming agent is suitably added in the process of producing the water-absorbent resin, that is, before or during the polymerization step. The human urine stabilizer, human blood stabilizer, antibacterial agent, deodorant, and fragrance can be added in each of the steps of producing a water-absorbent resin, producing a water-absorbing material, and producing a water-absorbing article. Of course, it is also possible to apply it to a fibrous base material in advance.

Further, the water-absorbent article of the present invention includes
JP-A-3-267370, JP-A-63-10667, JP-A-63-295251, JP-A-2708
No. 01, JP-A-63-294716, JP-A-64-64602, JP-A-1-231940, JP-A-1-243927, JP-A-2-305
No. 22, JP-A-2-153731, JP-A-2-153731
JP-A-21385, JP-A-4-133728,
The technology used for the sheet-like water-absorbing material proposed in Japanese Patent Application Laid-Open No. H11-156118 can be used according to the purpose.

[0074]

The present invention will be described more specifically with reference to Production Examples, Test Examples, Examples and Comparative Examples. The materials, reagents, ratios, operations, and the like shown below can be appropriately changed without departing from the spirit of the present invention. Therefore, the scope of the present invention is not limited to the following specific examples.

(Production Example 1) 58.3 parts by weight of a 48.5% by weight aqueous solution of sodium hydroxide, 6.4 parts by weight of water, and 125% by weight of an aqueous solution of 80% by weight acrylic acid, a crosslinking agent (N,
N'-methylenebisacrylamide) 0.15 parts by weight and an aqueous solution of 30% by weight of hydrogen peroxide 5.0 as an oxidizing agent
Solution A was prepared by adding parts by weight. Solution A had a monomer concentration of 60% by weight and a degree of neutralization of 50 mol%.

Separately, 125 parts by weight of an aqueous solution of 80% by weight of acrylic acid, 57.3 parts by weight of a 48.5% by weight aqueous solution of sodium hydroxide, 9.9 parts by weight of water, and a crosslinking agent (N,
Solution B was prepared by adding 0.15 parts by weight of (N′-methylenebisacrylamide) and 1.5 parts by weight of L-ascorbic acid as a reducing agent. The monomer concentration and degree of neutralization of solution B were the same as solution A.

The prepared solution A and solution B were mixed using the nozzle shown in FIG. The inner diameter of the nozzle of FIG.
3 mm, and five nozzles for each solution are arranged at intervals of 1 cm. Solution A and solution B flowing out of the nozzle
Was adjusted to 30 degrees, and the distance between the nozzle tips was adjusted to 4 mm. The solution A and the solution B were heated at a liquid temperature of 40 ° C., respectively, and supplied by a pump so that the flow rate was 5 m / sec.

The solution A and the solution B join at the exit of each of the nozzle pairs, and each of them
After the formation of the liquid column, the liquid drops were dropped in the gas phase (in air, at a temperature of 50 ° C.) while the polymerization proceeded as droplets. Some of the droplets collide with each other in the gas phase to form agglomerated particles, and fall onto a polyester nonwoven fabric substrate (basis weight: 30 g / m ² ) located 3 m below the tip of the nozzle, and The polymerization was completed on the material. At the same time, a part of the liquid droplets fell on the substrate, and after forming aggregated particles on the substrate, polymerization was completed on the substrate. Thus, the water-absorbing polymer was supported on the substrate. The supported polymer was dried until the water content of the polymer became 5% to obtain a water-absorbing material A having a polymer support amount of 200 g / m ² . Optical micrographs of the water absorbing material A are shown in FIGS.

(Production Example 2) Instead of the solution A used in Production Example 1, 125 parts by weight of an 80% by weight aqueous solution of acrylic acid was
80.4 parts by weight of 48.5% by weight potassium hydroxide, 2.0 parts by weight of water, 0.15 part by weight of a crosslinking agent (N, N'-methylenebisacrylamide) and 30% by weight of peroxide as an oxidizing agent Using a solution prepared by adding 5.0 parts by weight of a hydrogen aqueous solution, 48.5% by weight was added to 125 parts by weight of an aqueous solution of 80% by weight acrylic acid instead of the solution B used in Production Example 1.
80.4 parts by weight of potassium hydroxide, 5.5 parts by weight of water, and a crosslinking agent (N, N'-methylenebisacrylamide) 0.1
5 parts by weight and 1.5% of L-ascorbic acid as a reducing agent
A water-absorbing material B was obtained in the same manner as in Production Example 1 except that a solution prepared by adding parts by weight was used.

(Production Example 3) The same operation as in Production Example 1 except that the nonwoven fabric substrate made of polypropylene / polyethylene (basis weight: 100 g / m ² ) was used instead of the nonwoven fabric substrate made of polyester used in Production Example 1. To obtain a water-absorbing material C.

(Production Example 4) The same operation as in Production Example 1 except that a rayon nonwoven fabric substrate (basis weight: 50 g / m ² ) was used instead of the polyester nonwoven fabric substrate used in Production Example 1. To obtain a water-absorbing material D.

(Production Example 5) The water-absorbing material A (water content of the polymer: 20%) obtained in Production Example 1 before drying was 1000 mJ / c.
After irradiating with ultraviolet rays of m ² , the supported polymer was dried until the water content of the polymer became 5%, whereby a water absorbing material E was obtained.

(Production Example 6) An absorbent composite F was prepared in the same manner as in Production Example 1 except that the inner diameters of the nozzles for Solution A and Solution B used in Production Example 1 were changed to 0.20 mm. Obtained.

(Production Example 7) Instead of the solution A used in Production Example 1, 100 parts by weight of an aqueous solution of 80% by weight of acrylic acid was added to
27.4 parts by weight of maleic anhydride, 68.9 parts by weight of 48.5% by weight sodium hydroxide, 18.0 parts by weight of water, 0.15 of a crosslinking agent (N, N'-methylenebisacrylamide)
Using a solution prepared by adding 5.0 parts by weight of a 30% by weight aqueous hydrogen peroxide solution as an oxidizing agent and 100 parts by weight of an 80% by weight aqueous solution of acrylic acid instead of the solution B used in Production Example 1 , Maleic anhydride 27.4 parts by weight, 4
8.5% by weight of 68.9 parts by weight of sodium hydroxide, water 2
Production Example 1 except that a solution prepared by adding 1.5 parts by weight, 0.15 parts by weight of a crosslinking agent (N, N'-methylenebisacrylamide) and 1.5 parts by weight of L-ascorbic acid as a reducing agent was used. By performing the same operation as described above, an absorbent composite G was obtained.

(Production Example 8) Water-absorbing material A obtained in Production Example 1
A 5% aqueous solution of ethylene glycol diglycidyl ether was sprayed through a spray nozzle to impregnate the polymer, and then dried until the water content of the polymer became 5% to obtain a water absorbing material H. Was.

(Production Example 9) Absorbent composite I was obtained in the same manner as in Production Example 1 except that the amount of the polymer carried was changed to 100 g / m ² .

(Production Example 10) Solution A prepared in Example 1
Was heated to a liquid temperature of 40 ° C., and supplied by a pump using a nozzle having an inner diameter of 0.13 mm so as to have a flow rate of 5 m / sec.
The solution A formed a liquid column from the tip of the nozzle, then dropped as a droplet in the gas phase (in air, at 50 ° C.). The droplets were received on a polyester nonwoven fabric substrate (basis weight: 30 g / m ² ) placed 3 m below the tip of the nozzle, and the solution B prepared in Example 1 was sprayed by the same operation as the solution A. . The solution A and the solution B reacted on the substrate, and the polymerization proceeded to form a water-absorbing polymer. This was dried until the water content became 5% to obtain a water-absorbing material J having a polymer carrying amount of 200 g / m ² . An optical microscope photograph of the water absorbing material J is shown in FIG. The scale in the photograph is 1.5 mm.

(Production Example 11) The same operation as in Example 1 was performed except that the polyester nonwoven fabric substrate was placed 20 cm below the tip of the nozzle in Example 1, and polymerization proceeded on the substrate. A water-absorbing material L without forming aggregated granules was obtained.

(Production Example 12) The same operation as in Example 1 was carried out except that the polyester nonwoven fabric substrate was placed 5 m below the tip of the nozzle in Example 1, the polymerization was almost completed on the substrate. The water-absorbing material M from which the aggregated particles fell was obtained.

(Production Example 13) A water-absorbing material N was obtained by the method described in Example 1 of JP-A-9-67403.
FIG. 6 shows an optical microscope photograph of the water absorbing material N. The scale in the photograph is 500 μm.

(Production Example 14) A water-absorbing material P was obtained by the method described in Example 1 of JP-A-9-239912.

(Production Example 15) 60% with sodium hydroxide
N, N'-methylenebisacrylamide was added to the neutralized acrylic acid in an amount of 0.07 mol% (based on the pre-neutralization) with respect to the acrylic acid to obtain a partially neutralized aqueous solution of acrylic acid (monomer concentration 50 wt. %) To 237.4 parts by weight,
Solution A was prepared by adding 9 parts by weight of a 30% by weight aqueous hydrogen peroxide solution. Also, a solution B was prepared by adding 1.0 part by weight of L-ascorbic acid to 237.4 parts by weight of the same aqueous solution of acrylic acid. The prepared solution A and solution B were coated on a floor with a polyester non-woven fabric (fiber diameter 25 to 30 μm, basis weight 35 g /
m ² ) was discharged at a rate of 5 m / sec from the respective nozzles (inner diameter 0.1 mm) arranged so as to face each other at a height of 3 m from the floor surface at an upper portion of the polymerization chamber where the m ² ) was placed. The two liquids collided in the air to form droplets, and were dropped on a nonwoven fabric as a fibrous base material while being polymerized in an atmosphere at 40 to 50 ° C. Next, the nonwoven fabric to which the particles in the course of polymerization had adhered was removed from the polymerization chamber, and heated to complete the polymerization, thereby obtaining a water-absorbing material Q. The content of the water-absorbing polymer particles in the obtained water-absorbing material Q was 200 g / m ² . The particle diameter of the polymer particles was 100 to 600 μm for the primary particles, and the particle diameter of the aggregated granular material in which the primary particles were aggregated was 300 to 3000 μm. The proportion occupied by the aggregated granules was about 90% or more.

(Test Example) The water absorbing materials obtained in Production Examples 1 to 14 were measured and tested by the following methods. (1) Proportion of Polymer Forming Agglomerated Granules After taking scanning micrographs (SEM photographs) of a plurality of portions of the water absorbing material, 100 particles were arbitrarily selected to determine the presence or absence of aggregation. Assuming that the density of the agglomerated particles is uniform, the ratio of the polymer to the agglomerated particles was calculated.

(2) Average Particle Size of Agglomerated Particles After taking SEM photographs of a plurality of locations of the water-absorbing material, the
Individual particles were selected, the particle diameter was measured, and the average of the measured values was determined.

(3) Residual unreacted polymerizable monomer concentration 0.5 g of the water-absorbing material was precisely weighed, added to 1 liter of ion-exchanged water in a 2 liter beaker, and sufficiently stirred for about 10 hours. Swelled. 20 polymer gels after swelling
The mixture was filtered through a 0-mesh sieve, and the filtrate was analyzed by high performance liquid chromatography. Separately, a monomer standard solution having a known concentration was prepared, and a calibration curve was prepared therefrom to determine the absolute concentration.

(4) Support strength of water-absorbing polymer on fibrous base material 60 mm × 300 mm (thickness: 0.5 to 20 m) of water-absorbing material
m) was made to absorb saturated water with physiological saline, and then placed on a stone table.
Roller of 5mm, width 60mm and weight 4kg is 10cm
The weight of the water-absorbing polymer dropped from the sample when the sample was reciprocated 5 times at a speed of / second was weighed, and was evaluated by the loading A expressed by the following formula. Those having a loading ratio of 60% or more are preferable since they have practical loading strength, and those having a loading ratio of 70% or more are more preferable. A (%) = [(W0−w) / W0] × 100 In the formula, W0 represents the dry weight of the water-absorbing polymer in the sample, and w represents the dry weight of the water-absorbing polymer dropped.

(5) Absorption capacity of physiological saline About 1.0 g of a water-absorbing material and about 200 g of physiological saline having a concentration of 0.9% are weighed and placed in a 300 ml beaker, and left standing for about 4 hours. The polymer was sufficiently swollen with saline. Next, after draining with a 100 mesh sieve, the physiological saline water absorption capacity B was calculated according to the following formula,
The water-absorbing ability of the supported water-absorbing polymer was evaluated. B = (W1-W2) / W3 In the formula, W1 represents the weight of the water-absorbing material after water absorption, W2 represents the weight of the base material alone after water absorption, and W3 represents the weight of the water-absorbing polymer supported on the water-absorbing material.

(6) Water absorption speed About 1.0 g of a water-absorbing material and about 200 g of physiological saline having a concentration of 0.9% were weighed and placed in a 300 ml beaker, and left for 5 minutes. The polymer was swollen. Then, after draining with a 100 mesh sieve,
Physiological saline water absorption capacity B was calculated according to the above equation, and the water absorption rate was used to evaluate the water absorption rate of the water-absorbing polymer carried.

(7) Polymerization rate when dropped onto a substrate A beaker containing methanol weighed so that the liquid level of methanol is located at the position where the substrate is placed is placed, and the reaction mixture obtained by initiating the polymerization is Droplets were formed in the gas phase, and the aggregated granules during the polymerization dropped into the beaker containing methanol. The amount of the monomer in methanol was measured by liquid chromatography. Further, the polymer in methanol was dried under reduced pressure at 130 ° C. for 3 hours, and then the weight was measured. The polymerization rate was calculated from the respective weights according to the following formula (Mp is the weight of the polymer, Mm is the weight of the monomer). Polymerization rate = Mp / (Mm + Mp) × 100

(8) Frequency Intensity Ratio Using a scanning electron microscope (Model S2400, manufactured by Hitachi, Ltd.), a photograph at a magnification of 160 or 300 was obtained for the aggregated granular material. The particle contours of these photographs were faithfully traced on a tracing paper with a mechanical pencil (HB, 0.5 mm diameter), and the obtained trace image was further reduced by half.
The original reduced for image analysis. Next, an image was captured at a resolution of 75 dpi using a scanner (CanoScan 300, manufactured by Canon Inc.). The resolution of the measurement length in the captured image at this time is 2.3 μm (80
Times) or 1.25 μm (150 times). Further, after filling in the inside of the captured outline image (for example, commercially available softwares such as Adobe Photoshop and NIH)
image can be used), and converted to a text file.

A figure in which the inside including the contour is filled is defined as a binary figure (0, 1), and the center of gravity (Gx, y) is obtained. If all of the four pixels on the upper, lower, left, and right sides of the target black pixel are “1”, the outline (closed curve of the graphic boundary line) is obtained as a pixel inside the graphic. Next, the black pixels constituting the contour are continuously traced, and m
The coordinate array (Yi, Xi) of the contour line composed of the pieces of data was obtained. The distance from the center of gravity to the pixels forming the contour was determined for all contour coordinate arrays, and then the distance from the center of gravity was normalized. For normalization, the distance from the center of gravity was divided by the average distance, and “1” was subtracted to obtain the normalized distance. Normalized distance = (distance from center of gravity / average distance)-1

Before the frequency analysis of the normalized distance, the number of data points is different for each particle.
It was standardized to 12 points. 5 data from m normalized distance data
In order to convert the data into twelve data, interpolation was performed using data at two points sandwiching the data to be obtained. The normalized distances in the 512 data array were subjected to Fourier transform to obtain a power spectrum. The power spectrum was integrated from the low frequency side to the high frequency side to obtain an integrated value of the power spectrum.

In order to define the characteristics of the figure, the ratio of the integral value of the frequency 5 (Ipw, 5) to the integral value of the frequency 20 (Ipw, 20) as the integral value of the power spectrum was defined as the frequency intensity ratio. The frequency intensity ratio is large for a figure like an ellipse (a figure with many low frequency components), and a small value for a complicated contour (a figure with many high frequency components). Frequency intensity ratio = (Ipw, 5) / (Ipw, 20)

(9) Declination by Declination Analysis The deviation (Δi) from the coordinate array (Yi, Xi) of the contour
θ) was determined. The variation of the argument is defined by the following equation.
That is, the declination change (Δθi) of the i-th contour data is n times smaller than the i-th data (Xi, Yi) and the i-th data.
A vector connecting the data (Xi + n, Yi + n) preceding the data and the data (Xi-n,
Yi-n) and the direction of the vector connecting the i-th data (Xi, Yi). If the direction is the same, the angle of change of the argument is 0 degree. The direction of change is not distinguished between right and left. Δθi = (tan-1 (Yi + n-Yi) / (Xi + n-Xi)-tan-1 (Yi-
Yi-n) / (Xi-Xi-n)) x180 / π

In the case of n = 1, the minimum change angle is 45 degrees (π / 4 radian), so that the step width is too large and is easily affected by the digitization error. The change angle average angle of the argument was obtained by the following equation. Average angle of change in declination = (ΣΔθi-360xn) / number of data (m) Here, the correction term “360xn” in the equation is corrected because the total change in declination is 360 degrees even in the case of a circle. . Since n is the sum of all data, n
This is a correction for summing up the change in the rotation angle.

The average angle of change in declination is a value that defines the complexity of the particle contour, and is a large value for a complex shape having many irregularities in the contour. In these data processing, since the coordinate data is a contour and a closed curve, the coordinate array (X
(1, Y1) and (Xm, Ym) were calculated in consideration of their continuity. Numerical values were randomly selected.
The average of more than one particle was used.

(10) Ratio of Longest Diameter to Shortest Diameter The longest diameter and the shortest diameter of the aggregated granular material were determined from the image processing diagram of the aggregated granular material. Here, the longest diameter and the shortest diameter indicate the longest distance and the shortest distance as the diameter of the aggregated granular material, and the longest diameter and the shortest diameter are not necessarily orthogonal. The ratio between the longest diameter and the shortest diameter was determined by dividing the longest diameter by the shortest diameter. If the ratio of the longest diameter to the shortest diameter is less than 1.2, the shape is not a cohesive granular structure. The following table summarizes these measurement and test results.

[0108]

[Table 1]

(Examples and Comparative Examples) Prepared water absorbing material Q
, And six types of water-absorbing articles (diapers) were manufactured using the water-absorbing material N. As the structure of the water-absorbent article, the structure specified in Table 2 was selected from FIGS. The water absorption surface was manufactured so as to be the upper surface in the figure. Each structure of polyethylene film 16 (basis weight 20 g / m ^2), fluff pulp layer 13 (basis weight 110.5 g / m ^2), water absorbent of the water-absorbing polymer particles 15 immobilized on a fibrous substrate 14, Teisshu It consists of paper 12 (basis weight 18 g / m ² ) and polyester fiber nonwoven fabric 11 (basis weight 30 g / m ² ). However, in the structure of FIG. 7E, the water-absorbing polymer particles are dispersed in fluff pulp so as to be uniform, instead of the water-absorbing material in which the water-absorbing polymer particles are bound only on one surface of the fibrous base material. The pulp mix was used. Pulp mix
A water-absorbing polymer particle obtained in the same manner as described above except that it was not attached to the nonwoven fabric, and the above-mentioned fluff pulp were prepared by combining the water-absorbing polymer with 200 m ² / g and the pulp with 256 g / m ² . .

The absorption rate of artificial urine and the amount of artificial urine released by pressurization were measured for each manufactured diaper by the following methods. A cylinder having an inner diameter of 40 mm and an open top is attached to the center, and a portion surrounded by the cylinder has a diameter of 5 mm.
Acrylic plate (100 × 100 × 10 mm, total weight 15
0 g) was placed on the center of each manufactured diaper (180 × 180 mm), and a disk (500 g) having a diameter of 100 mm and a hole having a diameter of 45 mm at the center was inserted through the cylinder and placed thereon. 25 ml of artificial urine was placed in a cylinder, and the time until this was absorbed was measured with a stopwatch. After 10 minutes, remove the disk and acrylic plate, and remove the filter paper (ADVANTE).
C No. 424, 100 × 100 mm, manufactured by Toyo Roshi Kaisha Co., Ltd.) were placed in the same position as the acrylic plate on the diaper, and a 4 kg weight was placed on the filter paper.
After 5 minutes, the weight was removed, the weight of the filter paper was measured, and the amount of artificial urine absorbed by the filter paper was measured. The above measurement was repeated three times. The results are shown in the table below. The unit of water absorption speed is seconds,
The unit of the amount of released water is g.

[0111]

[Table 2]

When the results of Sample 1 and Sample 2 are compared, the diaper of Sample 1 having the water-absorbing surface of the water-absorbing polymer particles is compared with the diaper of Sample 2 of the present invention having the surface of the fibrous base material as the water-absorbing surface. As a result, the second and third water absorption rates are significantly reduced. In the diaper according to the present invention, the sample 3 in which the fluff pulp layer is disposed on the water-absorbing polymer particle side absorbs more than the sample 4 in which the fluff pulp layer is disposed on the fibrous base material side. Excellent in both speed and water release. Sample 5 is a conventional diaper, and the second and third water absorption rates are low.

The amount of movement of the water-absorbing polymer particles of the diaper when the force acting to rub the diaper was repeatedly applied to the diaper of Sample 2 and the diaper of Sample 5 produced above was measured. did. The measurement was 180 × 180 m on a shaking table where 50 times the weight of water-absorbent resin was absorbed.
m, and a 120 × 120 mm acrylic plate curved in a semicircle was placed on the diaper so that the center of the outside of the semicircle coincided with the center of the diaper. An insertion portion for supporting the weight is provided in the center of the semicircular inside, and a T-shaped weight (3 kg) support having a support attached to the center of a 100 × 100 mm plate is loosely inserted therein. did. When the shaking table is shaken left and right, the weight tilts left and right about the column, thereby moving the acrylic plate left and right as if rubbing the diaper. After shaking the shaking table at 80 reciprocations / minute for 5 minutes, the center of the diaper was
It cut out to the size of 0x100 mm, and measured the reduction rate of the water-absorbing polymer particle. As a result, the reduction ratio of the water-absorbing resin was 15% in the diaper of Sample 2, but was 29%, which was about twice as large in the diaper of Sample 5.

As described above, when the same water-absorbing material was used, it was found that adopting the structure of the present invention was preferable in terms of the water absorption speed, the amount of released water, and the movement of the water-absorbing polymer particles. This is the same when the water absorbing materials A to I, M, and N are used instead of the water absorbing material Q. As the type of the water-absorbing material, water-absorbing materials A to I, M, and N are preferable from the viewpoints of water-absorbing ability, water-absorbing speed, and the supporting strength of the water-absorbing polymer particles. Was.

[0115]

The water-absorbent article of the present invention has a high water absorption rate, a large amount of water absorption, and is excellent in the fixability of the swollen gel after absorbing water. Further, the water-absorbent article of the present invention exhibiting such excellent performance is extremely useful and useful because it can be easily and inexpensively manufactured.

[Brief description of the drawings]

FIG. 1 is a schematic view showing an example of a nozzle structure used when manufacturing a water absorbing material used in the present invention.

FIG. 2 is an optical micrograph of a water-absorbing material A produced in Production Example 1.

FIG. 3 is an optical micrograph of a water-absorbing material A produced in Production Example 1.

FIG. 4 is an optical micrograph of a water-absorbing material A produced in Production Example 1.

FIG. 5 is an optical micrograph of a water absorbing material J produced in Production Example 10.

FIG. 6 is an optical microscope photograph of a water absorbing material N manufactured in Production Example 13.

FIG. 7 is a cross-sectional view illustrating a structure of a water-absorbent article manufactured in an example.

[Explanation of symbols]

 1: Nozzle for first liquid 2: Nozzle for second liquid 3: Solution A 4: Solution B 11: Non-woven fabric 12: Paper 13: Fluff pulp 14: Fibrous base material 15: Water-absorbing polymer particles 16: Polyethylene film

Claims (26)

[Claims] 1. A water-absorbing material comprising a water-absorbing material having water-absorbing polymer particles immobilized on one surface of a fibrous base material, and a water-absorbing article configured such that the water-absorbing polymer particles absorb an aqueous liquid through the fibrous base material. A water-absorbent article wherein the absorbent is produced through a step of adhering water-absorbing polymer particles that are undergoing polymerization in a gas phase to one surface of a fibrous base material. 2. The water-absorbent article according to claim 1, wherein at least a part of the water-absorbent polymer particles forms an aggregated particle in which primary particles are bound to each other. 3. The water-absorbent article according to claim 2, wherein 30% by weight or more of the water-absorbent polymer particles constitute the aggregated granules. 4. A part of the primary particles constituting the aggregated granular material does not adhere to the fibrous base material.
The water-absorbent article according to 1. 5. An average particle diameter of the primary particles is 50 to 10.
The water-absorbent article according to any one of claims 2 to 4, which has a thickness of 00 µm. 6. The aggregated granular material has an average particle size of 100 to 100.
The water-absorbent article according to any one of claims 2 to 5, which has a size of 3000 µm. 7. A water-absorbing material having a water-absorbing material in which water-absorbing polymer particles are immobilized on one surface of a fibrous base material, and a water-absorbing article constituted such that the water-absorbing polymer particles absorb an aqueous liquid through the fibrous base material. At least a part of the water-absorbing polymer particles is composed of primary particles having an average particle diameter of 50 to 1000 μm, and 30% by weight or more of the primary particles are bonded to each other while substantially maintaining the particle shape. A water-absorbent article comprising an aggregated granular material having a shape satisfying the following conditions, wherein a part of the constituent particles of the aggregated granular material does not adhere to the fibrous base material. Average particle diameter (D) 100 ≦ D ≦ 3000 μm Declination (θ) by declination analysis 10 ≦ θ ≦ 25 5 Hz / 20 Hz intensity ratio of frequency analysis (k) 0.6 ≦ k ≦ 0.9 Ratio of long diameter (L) to shortest diameter (l) 1.2 ≦ L / l ≦ 15.0 8. The water-absorbent article according to claim 1, wherein the fibrous base material is in a sheet shape. 9. The fibrous base material is one or two selected from synthetic fibers, natural fibers, semi-synthetic fibers and inorganic fibers.
The water-absorbent article according to any one of claims 1 to 8, comprising at least one species. 10. The water-absorbent article according to claim 1, wherein the fibrous base material is a non-woven fabric. 11. The fibrous base material has a diameter of 10 to 50 μm.
The water-absorbent article according to claim 10, wherein the non-woven fabric is a nonwoven fabric made of the fibers of the above. 12. The basis weight of the fibrous base material is 10 to 10.
Absorbent article according to any of claims 1 to 11 is 0 g / m ^2. 13. 50% by weight of the water-absorbing polymer particles
The above constitutes the agglomerated granular material.
The water-absorbent article according to any one of the above. 14. 80% by weight of the water-absorbing polymer particles
The water-absorbent article according to claim 13, wherein the above constitutes the aggregated granular material. 15. The water-absorbent article according to claim 1, wherein the surface of the water-absorbent polymer particles is cross-linked. 16. The water-absorbent article according to claim 1, wherein said water-absorbent polymer particles are fixed on said fibrous base material at 50 to 300 g / m ² . 17. The water-absorbent article according to claim 1, wherein a layer made of fluff pulp is laminated on the water-absorbent material on the side of the water-absorbent polymer particles. 18. A fluff pulp layer is laminated on both surfaces of the water-absorbing material, and the weight of the fluff pulp layer laminated on the water-absorbing polymer particle side is laminated on the fibrous base material side. 18. The water-absorbent article according to claim 17, wherein the basis weight of the layer made of fluff pulp is larger. 19. The fluff pulp layer laminated on the water-absorbing polymer particle side of the water-absorbing material has a basis weight of 8
The weight is 0 to 250 g / m ^2.
19. The water-absorbent article according to 7 or 18. 20. The water-absorbing material forms droplets of a reaction mixture in which a polymerization is started by mixing an aqueous solution of a polymerizable monomer that gives a water-absorbing polymer and a redox-based polymerization initiator in a gas phase, The droplets are bound to each other in the gas phase and / or on the fibrous base material while maintaining their shapes substantially, to form aggregated granules, and the aggregated granules formed in the gas phase are applied to the fibrous base material. 20. The water absorption according to any one of claims 1 to 19, wherein the water absorption is produced by completing polymerization of the aggregated granules on the fibrous base material after the support and fixing the aggregated granules to the fibrous base material. Products. 21. The water-absorbent article according to claim 20, wherein the polymerization rate of the polymerizable monomer at the time of contact with the fibrous base material is 20 to 97%. 22. A droplet of the reaction mixture is mixed with an oxidizing agent constituting a redox-based polymerization initiator and a first liquid containing an aqueous solution of a polymerizable monomer, a reducing agent constituting a redox-based polymerization initiator, and a polymerizable monomer. 22. The water-absorbent article according to claim 20, which is formed by mixing a second liquid containing an aqueous solution in a gas phase. 23. The water-absorbent article according to claim 22, wherein the mixing is a step of colliding and mixing the first liquid and the second liquid under a liquid column state. 24. The polymerizable monomer comprising an aliphatic unsaturated carboxylic acid or a salt thereof as a main component.
The water-absorbent composite article according to any one of the above. 25. The method according to claim 20, wherein the polymerizable monomer is mainly composed of acrylic acid in which at least 20 mol% of carboxyl groups are neutralized with an alkali metal salt or an ammonium salt. Water absorbent articles. 26. The method according to claim 20, wherein the oxidizing agent constituting the redox polymerization initiator is hydrogen peroxide, and the reducing agent is L-ascorbic acid or an alkali metal salt of L-ascorbic acid. Absorbent articles.