JP2001172854A - Absorbent of water for hygienic material, and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an absorbent of water for a hygienic material, having improved mechanical strengths and the absorbency prevented from reduction thereof, and further to provide a method for producing the absorbent of water. SOLUTION: This absorbent of water is the one comprising (A) a fiber assembly, and at least a part of the fiber constituting the fiber assembly A is at least partially bound by a resin derived from at least one kind selected from (B) a water-based resin emulsion and (C) a powdery resin emulsified again. The resultant water absorbent can be produced, for example, by applying the water-based resin emulsion B to the fiber assembly A. The absorbent can also be produced by allowing the powdery resin C emulsified again to be present on the surface and/or the interior of the fiber assembly A, and further applying water thereto.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a water absorber used for sanitary materials such as disposable diapers, incontinence pads and sanitary napkins, and a method for producing the same.

[0002]

2. Description of the Related Art Sanitary materials such as disposable diapers, incontinence pads and sanitary napkins are made of water (hereinafter, "water" in the present specification refers to general water which may contain salts, solids, etc. Absorbents such as distilled water, ion-exchanged water and the like, specifically, for example, refer to bodily fluids such as urine and blood)
It is covered with paper etc., a part of the paper etc. is stopped with hot melt adhesive etc., and it is provided between the air permeable polymer sheet that directly hits the wearer's skin and the impermeable nonwoven fabric Having a structure. These sanitary materials are sanitary,
Characteristics such as high water absorption and water retention are required. This water absorber is usually a thin fiber aggregate made of pulp, and a water-absorbent polymer capable of absorbing and retaining a large amount of water is contained in the fiber aggregate as necessary. Contains.

[0003] However, since such a water absorber absorbs a large amount of water and has insufficient mechanical strength, the shape of the absorber is collapsed and broken by its own weight, and the water is absorbed inside the sanitary material. The absorber moves between the air-permeable polymer sheet and the nonwoven fabric, causing a bias in the distribution of the absorber inside the sanitary material. As a result, there is a problem that moisture cannot be sufficiently absorbed and leakage occurs. In order to solve this problem, there has been proposed a method of improving the mechanical strength of the moisture absorber by using a hot melt adhesive for bonding the absorber and the tissue (Japanese Patent Laid-Open No. 3-3706).
No. 2). However, in this method, the effect of improving the mechanical strength of the moisture absorber is small, and further, there may be a problem that the water absorption of the moisture absorber is reduced. Therefore, a decrease in water absorption is prevented, and a mechanical strength, particularly a moisture absorber used for a sanitary material having improved mechanical strength at the time of absorbing water, and a method for producing such a moisture absorber are required. I have.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above-mentioned problems, and an object of the present invention is to prevent the reduction of water absorption and improve the mechanical strength, particularly the mechanical strength at the time of water absorption. It is an object of the present invention to provide a moisture absorber for a sanitary material, a method for producing such a moisture absorber, and a sanitary material using such a moisture absorber.

[0005]

Means for Solving the Problems The present inventors have conducted various studies on preventing the reduction of water absorption while improving the mechanical strength of a water absorber, particularly the mechanical strength at the time of water absorption. As described in detail below, in (A) a water absorber comprising a fiber aggregate, (A) fibers forming the fiber absorber are combined with (B) an aqueous resin emulsion and (C) re-emulsified. At least one selected from shaped powder resins
By bonding using a resin derived from the seed,
(A) The present inventors have found that it is possible to prevent the reduction of water absorption while improving the mechanical strength of a water absorber comprising a fiber aggregate, particularly the mechanical strength at the time of water absorption, and have completed the present invention. It is.

The inventor of the present invention has proposed (A) a method of improving the mechanical strength of a moisture absorber comprising a fiber aggregate by increasing the strength of the fiber aggregate by bonding the fibers constituting the fiber aggregate. I thought it was effective to improve. Then, in order not to decrease the water absorption while increasing the strength of the fiber assembly, it was thought that (A) the fiber of the fiber assembly should be provided with an appropriate crosslinked structure by resin. That is, it was thought that the problem could be solved by using (A) a resin that provides a resin that imparts an appropriate number of crosslinked structures to the fibers of the fiber assembly.

[0007] From the above considerations, the inventor has found that:
It has been found that (B) an aqueous resin emulsion and (C) a re-emulsifiable powder resin can be used to provide a resin that imparts a moderate number of crosslinked structures to the fibers of the fiber assembly. It is completed. Each of the components that are the main components of the adhesive force between the (B) aqueous resin emulsion and (C) the re-emulsifiable powder resin is, for example, a granular or film-like resin. Therefore, (A) these resins invade between the fibers forming the fiber aggregate, and the fibers that come into contact with each other can be bonded to each other.

[0008] The present invention has been made based on the above study, and according to one gist of the present invention,
(A) a water absorber comprising a fiber aggregate,
(A) The fibers forming the fiber absorber are combined with each other using a resin derived from at least one selected from (B) an aqueous resin emulsion and (C) a re-emulsifiable powder resin. To provide a water absorber for sanitary materials.

BEST MODE FOR CARRYING OUT THE INVENTION

In the present invention, the term “(A) fiber aggregate” refers to, for example, a fiber aggregate particularly made of pulp,
This is a collection of fibers that are made by appropriately treating a plant as a raw material, and more specifically, an aggregate of fibers produced by pulverizing pulp. It is not particularly limited as long as it is generally used as a moisture absorber for sanitary materials.

In the present invention, the fiber aggregate (A) can contain an absorbent polymer. For example, it may be present therein and / or on the surface. In the present invention, "absorbent polymer" refers to a polymer that can absorb and retain a large amount of water, and is particularly limited as long as it is used as an absorbent polymer for sanitary materials. is not.

Examples of the absorbent polymer include synthetic polymers such as polyacrylates, polyvinyl alcohols and polyacrylamides, and natural polymers such as starches and celluloses. These can be used alone or in combination. Such an absorbent polymer can be produced by a known method, and a commercially available one can be used. For example, AquaKeep (trade name) manufactured by Sumitomo Seika Co., Ltd. and Sanyo Chemical Industries Sunwet (trade name) manufactured by K.K.

In the present invention, "absorbent polymer"
(A) It is preferable to add 0.1 to 50 g, more preferably 1 to 20 g, per 100 g of the fiber aggregate,
It is particularly preferred to add 1 to 5 g. The form in which the “absorbent polymer” is present in the fiber aggregate (A) may be a form usually used for a fiber aggregate for a sanitary material, and must be a form that gives an unfavorable effect to the properties of the fiber aggregate. It is not particularly limited. For example, a granular absorbent polymer may be sprinkled on the fiber aggregate, a granular or massive absorbent polymer may be dispersed in the fiber aggregate, or in the fiber aggregate. The absorbent polymer may be inserted in the form of a sheet.

In the present invention, "(B) water-based resin emulsion" is an emulsion of a resin using water as a medium, and the resin obtained by drying the resin is used to bond (A) the fibers of the fiber assembly to each other. There is no particular limitation as long as it can be performed. The glass transition temperature (hereinafter also referred to as “Tg”) of the resin obtained by drying is −50 to
100 ° C is preferred, and -20 to 80 ° C is more preferred.

In the present invention, "glass transition temperature" refers to a value obtained based on measurement of viscoelasticity at various temperatures as described below. That is, using DVE4 (trade name) manufactured by Rheometrics Co., Ltd., the viscoelasticity of the resin (in the form of a film) was measured, and the frequency was 1H in the shear mode.
The stress with respect to the strain given to the resin is measured by z, and the phase difference δ between the stress and the strain is obtained. This measurement is repeated in a predetermined temperature range. The glass transition temperature is defined as the tangent of the phase difference δ between the stress and the strain, that is, the temperature at which tan δ gives the peak top. Therefore, from the value of δ for the temperature measured in the measurement of the viscoelasticity of the resin,
A curve of tan δ versus temperature is obtained, and the temperature giving the peak top of the curve is defined as the glass transition temperature.

Examples of the aqueous resin emulsion (B) include an acrylic resin emulsion, a vinyl acetate resin emulsion, a vinyl chloride-vinyl acetate copolymer emulsion, a styrene-butadiene copolymer emulsion, and an ethylene-vinyl acetate emulsion. Examples thereof include a polymer emulsion, a polyester resin emulsion, a urethane resin emulsion, a nylon resin emulsion, and a polyolefin emulsion. In addition, reference can be made to reference materials related to the voluntary standards for sanitary treatment products (issued by the Japan Federation of Sanitary Materials Industries, October 1998). These (B) aqueous resin emulsions can be used alone or in combination.

Such an aqueous resin emulsion (B) can be produced by a known method. Examples of the production method include a conventional emulsion polymerization method (see Soichi Muroi, Chemistry of Polymer Latex, pp. 51-54, published by Kobunshi Kankokai 1970) and a forced emulsification method (Japanese Patent Publication No. 6-102748). No., Japanese Patent Application Laid-Open No. HEI 10-301). Further, a commercially available aqueous resin emulsion (B) can be used, but the present invention is not limited thereto. In addition, in these (B) aqueous resin emulsions,
It is preferable to use those having low odor or no odor.

In the present invention, "water" refers to general water, for example, distilled water, ion-exchanged water, pure water, etc., but within a range that does not adversely affect the properties of the absorber of the present invention. Water-soluble or water-dispersible organic solvents, which may contain monomers, oligomers, and the like, and are usually used in the production of an aqueous resin emulsion, an emulsifier, a polymerization initiator, a reducing agent, a chain transfer agent, and Various additives such as a pH adjuster may be included.

In the present invention, "(C) re-emulsifiable powder resin" is a powder obtained by drying a synthetic resin emulsion obtained by emulsion polymerization in the form of particles, and is a powder that can be re-emulsified by the presence of water. A resin obtained by drying the emulsion after re-emulsifying the re-emulsified powder resin (substantially (C) the re-emulsified powder resin itself)
However, there is no particular limitation as long as (A) the fibers of the fiber assembly can be bonded to each other. (C)
The glass transition temperature of the re-emulsifying powder resin is -50 to 100.
C is preferable, and -20 to 80 C is preferable.

From the above method (C) for producing a re-emulsifiable powder resin, (C) shows that the particles of the re-emulsifiable powder resin are formed by aggregating the particles of the synthetic resin emulsion as the raw material. Here, the term "re-emulsification" means that, due to the presence of water, the particles of the re-emulsifiable powder resin formed by the aggregation of the particles of the synthetic resin emulsion of the raw material are uncoagulated, and the particles of the re-emulsifiable powder resin become Forming an aqueous emulsion with the same size as the particles of the synthetic resin emulsion, which means that the coagulation of the particles of the re-emulsifying powder resin does not dissolve, and the particles of the re-emulsifying powder resin remain as they are. Don't say dispersing. Therefore, the (C) re-emulsifiable powder resin can have the same properties as the original synthetic resin emulsion by re-emulsifying.

However, in the actual production of the water absorber of the present invention, it is not necessary to completely re-emulsify (C) the re-emulsifiable powder resin in the presence of water, and the present invention aims at (A) It suffices if the bonding of the fibers of the fiber assembly can be achieved.

As such a (C) re-emulsifiable powder resin, for example, the acrylic resin-based emulsion, vinyl acetate resin-based emulsion, vinyl chloride-vinyl acetate copolymer-based emulsion used as the above-mentioned (B) aqueous resin emulsion. And styrene-butadiene copolymer-based emulsions, ethylene-vinyl acetate copolymer-based emulsions, polyester resin-based emulsions, urethane resin-based emulsions, nylon resin-based emulsions, and polyolefin-based emulsions. When these aqueous resin emulsions are emulsion-polymerized, when emulsion polymerization is performed using a water-soluble polymer such as polyvinyl alcohol as a protective colloid, when the aqueous resin emulsion is spray-dried, the particles of the emulsion are hardly blocked, and thus are obtained. (C) The re-emulsifiability of the re-emulsifiable powder resin is favorable, which is preferable.

Further, when the aqueous resin emulsion is spray-dried in the presence of an anti-binder, the particles of the emulsion are less likely to be blocked, and the re-emulsifiable property of the resulting re-emulsifiable powder resin (C) is favorable, which is preferable. As an anti-caking agent, for example,
Examples thereof include fine particle powders of aluminum silicate, silica, calcium carbonate, and the like. These (C) re-emulsifiable powder resins can be used alone or in combination.

(C) The re-emulsifiable powder resin can be produced by a known method, but a commercially available resin can be used. When (A) the fiber aggregate contains an absorbent polymer, it is preferable to use at least (C) a re-emulsifiable powder resin, and (B) even if used together with an aqueous resin emulsion, The re-emulsifying powder resin may be used alone.

(B) 100 g of the aqueous resin emulsion and (C) the re-emulsifiable powder resin (total of (B) and (C))
Preferably, 0.1 to 50 g, more preferably 1 to 20 g, and particularly preferably 1 to 10 g of solid content per (A) fiber aggregate. still,
(B) The concentration of the solid content (or the water content) of the aqueous resin emulsion should be appropriately selected according to the method for producing the water absorber.

Several methods are conceivable as a method for producing the above-mentioned water absorber for sanitary materials. This will be described below. According to another aspect of the present invention, there is provided a method for producing a new moisture absorber for a sanitary material, comprising: (A) a method for producing a moisture absorber comprising a fiber aggregate, (A) A method for producing a water absorber for a sanitary material, wherein (B) an aqueous resin emulsion is applied to a fiber assembly.

In the present invention, “application” means that an appropriate amount of a fluid is allowed to exist on the fiber aggregate (A).
A normal application method can be used, and examples thereof include coating, coating, and spraying. Here, the “coating” can be used without any limitation as long as it is a coating method conventionally used as a method for coating a fluid. Further, “coating” can be used without any limitation as long as it is a coating method conventionally used as a method for coating a fluid. The term “spray” can be used without limitation as long as it is a spray method conventionally used as a method for spraying a fluid. Here, 100 g of the aqueous resin emulsion (B) was used.
(A) 0.1 to 50 g in solid content with respect to the fiber aggregate
Is preferably applied, more preferably 1 to 20 g is applied, and particularly preferably 1 to 10 g.

In this production method, the aqueous resin emulsion (B) penetrates between the fibers of the fiber aggregate (A) by being applied to the fiber aggregate (A).
It is considered that the resin derived from the penetrated (B) aqueous resin emulsion bonds between the fibers in the (A) fiber aggregate. Therefore, (A) the mechanical strength of the fiber aggregate is improved, and the mechanical strength of the water absorber is increased. However, even if the water absorber absorbs the water, this bond may exist without being easily broken, so that the mechanical strength of the water absorber at the time of water absorption is also improved.

In this production method, after the aqueous resin emulsion (B) is applied to the fiber aggregate (A), the resultant is dried to produce the desired moisture absorber for a sanitary material. In the present invention, "drying" can be used without limitation as long as it is a drying method conventionally used as a drying method for removing moisture. For example, warm air drying, reduced pressure drying, natural drying, and the like can be exemplified.

In accordance with another aspect of the present invention, there is provided a method of manufacturing a new moisture absorber for a sanitary material, the method comprising: (A) manufacturing a moisture absorber comprising a fiber aggregate; A method for producing a moisture absorber for a sanitary material, comprising: (C) causing a re-emulsifiable powder resin to be present on the surface and / or inside of a fiber assembly (A) and applying water. It is. Here, the above-mentioned application method can be used for “application”.

In this production method, (C) the re-emulsifiable powder resin may be present on the surface or inside of the fiber assembly (A).
Examples thereof include a method of sprinkling on the surface of the fiber assembly, a method of mixing (C) the re-emulsifiable powder resin with the fiber assembly (A), and the like. Here, the “sprinkling method” can be used without limitation as long as it is a commonly used sprinkling method as a method of sprinkling powder. Furthermore, the “mixing method” can be used without limitation as long as it is a mixing method conventionally used as a method for mixing powders. Here, the (C) re-emulsifiable powder resin is preferably present in a solid content of 0.1 to 50 g, more preferably 1 to 20 g, and preferably 1 to 20 g, per 100 g of the (A) fiber aggregate.
It is particularly preferred that 0 g is present.

In this production method, (C) the re-emulsifiable powder resin is present on (A) the surface and / or inside of the fiber assembly, and (A) water is applied to the fiber assembly to regenerate the water. Emulsify. It is considered that the resin derived from the re-emulsified aqueous resin emulsion bonds the fibers in the (A) fiber aggregate. Therefore, (A) the mechanical strength of the fiber aggregate is improved, and the mechanical strength of the water absorber is increased. However, even if the water absorber absorbs the water, this bond may exist without being easily broken, so that the mechanical strength of the water absorber at the time of water absorption is also improved.

In this production method, water is added to (A)
Three modes are considered depending on the time of application to the fiber assembly. That is, when water is applied to the (A) fiber aggregate,
There are three embodiments, before (C) the re-emulsifiable powder resin is present on (A) the surface and / or inside of the fiber aggregate, at the same time as it is present, and after it is present. This production method is not particularly limited by the time at which water is applied to the (A) fiber assembly, but the time at which water is applied to the (A) fiber assembly is based on (C) the re-emulsifying powder resin. (A) It is preferable that the fibers are present on the surface and / or inside of the fiber assembly.

Further, as one embodiment of this manufacturing method,
A new method of manufacturing a moisture absorber for a sanitary material is provided, comprising (A) a method of manufacturing a moisture absorber comprising a fiber assembly, comprising applying water and (C) re-emulsifying. A method for producing a moisture absorber for a sanitary material, wherein the shaped powder resin is present on the surface and / or inside of the fiber aggregate (A) is preferred.

In this production method, the obtained moisture absorber for a sanitary material can be further dried to produce a desired moisture absorber for a sanitary material. Here, the above-mentioned drying method can be used for “drying”.

According to another preferred aspect of the present invention, there is provided a method for producing a new moisture absorber for sanitary materials, comprising (A) a method for producing a moisture absorber comprising a fiber aggregate. Water absorption for a sanitary material, wherein (C) the re-emulsifiable powder resin is present on (A) the surface and / or inside of the fiber assembly, and (B) an aqueous resin emulsion is applied. It is a method of manufacturing the body. Further, (B) an aqueous resin emulsion and (C) a re-emulsified powder resin (that is,
The sum of (B) and (C)) is preferably 0.1 to 50 g, more preferably 1 to 20 g, and more preferably 1 to 10 g as solids per 100 g of the (A) fiber aggregate.
It is particularly preferred that it be present. Here, the “existing” and “applying” methods can use the above-described methods of making them exist and applying methods, respectively.

In this production method, both (C) the re-emulsifiable powder resin and (B) the aqueous resin emulsion are used in combination. (A) The re-emulsifying powder resin to be present on the surface and / or inside of the fiber assembly is (A)
The water contained in the aqueous resin emulsion (B) applied to the fiber assembly results in an aqueous resin emulsion. It is considered that the resin derived from the resulting aqueous resin emulsion and (B) the aqueous resin emulsion bind the fibers in the (A) fiber aggregate. Therefore, (A) the mechanical strength of the fiber aggregate is improved, and the mechanical strength of the water absorber is increased. However, even if the water absorber absorbs the water, this bond may exist without being easily broken, so that the mechanical strength of the water absorber at the time of water absorption is also improved.

In this manufacturing method, three modes are considered depending on the timing of applying the aqueous resin emulsion (B) to the fiber aggregate (A). That is, the time when (B) the aqueous resin emulsion is applied to the (A) fiber aggregate is
There are three embodiments, before (C) the re-emulsifiable powder resin is present on (A) the surface and / or inside of the fiber aggregate, at the same time as it is present, and after it is present.

This production method is not particularly limited by the timing of applying the (B) aqueous resin emulsion to the (A) fiber aggregate, but the (B) aqueous resin emulsion is applied to the (A) fiber aggregate. It is preferable to perform this step after (C) the re-emulsifiable powder resin is present on the surface and / or inside of the fiber aggregate (A). Further, as one aspect of this production method, (B) when the aqueous resin emulsion is applied to the (A) fiber aggregate, (C) the re-emulsifying powder resin is applied to the surface of the (A) fiber aggregate and / or Preferably before it is present inside.

Further, in this production method, an appropriate amount of water can be applied to (A) the fiber aggregate as needed. The timing and amount of application of water can be appropriately selected. For example, as one embodiment of this manufacturing method,
(A) A method for producing a water absorber comprising a fiber assembly, wherein water is applied, and (C) the re-emulsifiable powder resin is present on (A) the surface and / or inside the fiber assembly. ,
(B) A method for producing a water absorber for sanitary materials, characterized by applying an aqueous resin emulsion, is preferred. Further, as another embodiment of the production method, (A) a method for producing a moisture absorber comprising a fiber aggregate, wherein (B)
An aqueous resin emulsion is applied, (C) the re-emulsifiable powder resin is present on the surface and / or inside of the fiber aggregate (A), and water is applied. Manufacturing methods are preferred.

In this production method, the obtained moisture absorber for a sanitary material can be further dried to produce a desired moisture absorber for a sanitary material. Here, the above-mentioned drying method can be used for “drying”.

As described above, all of the production methods of the present invention provide (A) a water-based resin emulsion and (C) a resin-based emulsion which provides a resin which imparts an appropriate number of crosslinked structures to the fibers of the fiber assembly. Since at least one selected from the emulsified powder resin is used, the method provides a method for producing a water absorber for a sanitary material, which has improved mechanical strength, particularly mechanical strength at the time of water absorption, and prevents reduction in water absorption. I do. Furthermore, the water absorber for sanitary materials manufactured by the above-described manufacturing method of the present invention has improved mechanical strength of the absorber, particularly the mechanical strength of the absorber at the time of water absorption, and reduces water absorption. The present invention provides a moisture absorber for sanitary materials having such properties.

In addition, the above-described water absorber of the present invention improves the mechanical strength, particularly the mechanical strength of the water absorber when absorbing water, and therefore the water absorber of the present invention is used as a sanitary material. Thus, the problem that the shape of the absorber is broken or broken by its own weight is reduced or eliminated. Further, the moisture absorber moves between the breathable polymer sheet and the nonwoven fabric inside the sanitary material, causing a bias in the distribution of the moisture absorber inside the sanitary material, and as a result, the moisture absorbability partially increases. The problem of the occurrence of defective sanitary materials due to the reduction is alleviated or eliminated. Accordingly, the present invention provides such a sanitary material.

The above-mentioned sanitary material is prepared by producing a water absorbent for a sanitary material of the present invention once and then using a conventionally known method for producing a sanitary material (for example, JP-A-8-337).
954 and JP-A-6-245955) by using the water absorbent of the present invention. Further, the method for producing a moisture absorber for a sanitary material of the present invention is described by using a conventionally known method for producing a sanitary material (see, for example, JP-A-8-337954 and JP-A-6-245955). The above-mentioned sanitary material can be manufactured by incorporating and utilizing as a part of.

[0044]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples and comparative examples. However, these examples are only one embodiment of the present invention, and the present invention is not limited by these examples. is not.

Example 1 (1) Production of water-based resin emulsion Polyvinyl alcohol (having a polymerization degree of 1700, saponification) was placed in a reactor equipped with a stirrer, a temperature controller, a reflux condenser, two drip tanks, a thermometer and a nitrogen inlet tube. The degree is 88 mol%, Co., Ltd.
5% by weight of Kuraray, PVA217 (trade name))
Was added in an amount of 85 parts by weight. 75 ° C with stirring
After that, 100 parts by weight of vinyl acetate and 15 parts by weight of a 1% aqueous solution of ammonium persulfate were added dropwise from separate dropping tanks over 4 hours. After the dropwise addition, the mixture was further stirred at 80 ° C. for 2 hours, cooled to room temperature, and water was added thereto to give a concentration of 50% by weight.
Thus, an aqueous resin emulsion of Example 1 was obtained.

The aqueous resin emulsion of Example 1 was added to 5
The resin was dried in a dryer at 0 ° C. for 48 hours to remove the solvent, and the aqueous resin emulsion of Example 1 was dried to obtain a resin (film). The glass transition temperature of the resin of Example 1 was obtained by measuring the stress with respect to the strain given to the urethane resin having a crosslinked structure at a frequency of 1 Hz in a shear mode using DVE4 (trade name) manufactured by Rheometrics. From the phase difference δ of the applied stress and strain, ta
nδ was calculated. The measurement was repeated at various temperatures to obtain a curve of tan δ against temperature. The temperature giving the peak top of the obtained curve was defined as the glass transition temperature. The glass transition temperature was 60 ° C.

(2) Manufacture of moisture absorber for sanitary material 12 cm × 12 cm × 0.5 cm made of ground pulp
Absorbent polymer (Aquakeep (trade name), manufactured by Sumitomo Seika Co., Ltd.) was sprinkled on the fiber assembly (with a basis weight of 8 g) at a weight ratio of 5 g per 100 g of the fiber assembly. Thereafter, the aqueous resin emulsion of Example 1 diluted to a concentration of 30% by weight was applied to the fiber assembly. The aqueous resin emulsion of Example 1 was applied using a spray so that the solid content of the aqueous resin emulsion was 5.5 g per 100 g of the fiber aggregate. Thereafter, drying was performed at 130 ° C. for 1 minute to obtain a moisture absorber for a sanitary material of Example 1. The moisture absorber was cut into a size of 2 cm × 12 cm to obtain a test piece.

(3) Evaluation of water absorber for sanitary material The strength of the water absorber for sanitary material and the breaking strength of the test piece were measured using Tensilon (RTM250 (trade name, manufactured by Orientec)). The evaluation was performed by measuring under the conditions of a head speed of 50 mm / min and a distance between chucks of 100 mm. The breaking strength was measured for the obtained test piece itself (at the time of drying) and the test piece to which 1 ml of physiological saline had been dropped (when wet). The breaking strength of the test piece of Example 1 when dried per cm was 1.46 × 10 ⁻³ N,
The breaking strength when wet per cm was 0.6 × 10 ⁻³ N. The results of Example 1 are shown in Table 1.

Example 2 A reactor equipped with a stirrer, a temperature controller, a reflux condenser, two drip tanks, a thermometer and a nitrogen inlet tube was charged with polyvinyl alcohol (polymerization degree: 1700, saponification degree: 88 mol%, )
5% by weight of Kuraray, PVA217 (trade name))
Was added in an amount of 85 parts by weight. 75 ° C with stirring
Then, a mixture of 25 parts by weight of vinyl acetate, 74 parts by weight of butyl acrylate and 1 part by weight of ethylene glycol dimethacrylate, and 15 parts by weight of a 1% aqueous solution of ammonium persulfate were each added from another dropping tank for 4 hours. It dripped over. After the dropwise addition, the mixture was further stirred at 80 ° C. for 2 hours, then cooled to room temperature, and polyvinyl alcohol (having a polymerization degree of 50
0, saponification degree: 88 mol%, manufactured by Kuraray Co., Ltd., PVA2
05 (trade name)) in an aqueous solution having a concentration of 25% by weight.
An aqueous resin emulsion of Example 2 having a concentration of 40% by weight was obtained in addition to 5 parts by weight.

Example 1 was repeated using the same method as described in Example 1 except that the aqueous resin emulsion of Example 2 was used instead of the aqueous resin emulsion of Example 1. The glass transition temperature of the solid content of the aqueous resin emulsion was measured. Further, in Example 1,
A method described in Example 1 except that the aqueous resin emulsion of Example 2 was applied to the fiber assembly so as to obtain 6.0 g per 100 g of the fiber aggregate instead of the aqueous resin emulsion of Example 1. Using the same method as described above, a water absorber and a test piece for a sanitary material of Example 2 were obtained,
The specimen was evaluated. The results are shown in Table 1.

Example 3 In Example 1, instead of 100 parts by weight of vinyl acetate, 48 parts by weight of butyl acrylate, 50 parts by weight of methyl methacrylate, 1 part by weight of methacrylic acid and 1 part by weight of γ-methacryloxypropyl Using a mixed solution of trimethoxysilane, 85 parts by weight of 5% by weight polyvinyl alcohol (polymerization degree is 1700, saponification degree is 88 mol%,
Instead of the aqueous solution (Kuraray Co., Ltd., PVA217 (trade name)), 1.5 parts by weight of a 60% by weight aqueous solution of sodium dodecylbenzenesulfonate and 1.5 parts by weight of polyoxyethylene sorbitan monolaurate were 105 parts by weight. A water-based resin emulsion of Example 3 having a concentration of 45% by weight was obtained in the same manner as in Example 1, except that an aqueous solution dissolved in some parts of distilled water was used.

The procedure of Example 3 was repeated, except that the aqueous resin emulsion of Example 3 was replaced with the aqueous resin emulsion of Example 3. The glass transition temperature of the solid content of the aqueous resin emulsion was measured. Further, in Example 1,
A method described in Example 1 except that the aqueous resin emulsion of Example 3 was applied to the fiber assembly so as to obtain 5.0 g per 100 g of the fiber aggregate instead of the aqueous resin emulsion of Example 1. Using the same method as described above, a water absorber and a test piece for a sanitary material of Example 3 were obtained,
The specimen was evaluated. The results are shown in Table 1.

Example 4 In Example 1, 29 parts by weight of butyl acrylate, 20 parts by weight of ethyl acrylate, 50 parts by weight of methyl methacrylate and 1 part by weight of ethylene glycol dimethacrylate were used instead of 100 parts by weight of vinyl acetate. Using a mixed solution, 85 parts by weight of 5% by weight of polyvinyl alcohol (polymerization degree is 1700, saponification degree is 88 mol%,
Example 4 having a concentration of 45% by weight using 1.0 part by weight of a polymerizable emulsifier (manufactured by Sanyo Kasei Kogyo Co., Ltd., JS2 (trade name)) instead of the aqueous solution of Kuraray, PVA217 (trade name). A water-based resin emulsion was obtained.

The procedure of Example 4 was repeated, except that the aqueous resin emulsion of Example 1 was replaced with the aqueous resin emulsion of Example 4. The glass transition temperature of the solid content of the aqueous resin emulsion was measured. Further, in Example 1,
A method described in Example 1 except that the aqueous resin emulsion of Example 4 was applied to the fiber assembly so as to obtain 5.5 g per 100 g of the fiber aggregate instead of the aqueous resin emulsion of Example 1. Using the same method as described above, a water absorber and a test piece for a sanitary material of Example 4 were obtained,
The specimen was evaluated. The results are shown in Table 1.

Example 5 In Example 1, 85 parts by weight of a mixture of 54 parts by weight of butyl acrylate, 45 parts by weight of methyl methacrylate and 1 part by weight of ethylene glycol dimethacrylate was used instead of 100 parts by weight of vinyl acetate. 5% by weight
1.0 part by weight of polyoxyethylene (20) sorbitan monolaurate was used in addition to an aqueous solution of polyvinyl alcohol (polymerization degree: 1700, saponification degree: 88 mol%, manufactured by Kuraray Co., Ltd., PVA217 (trade name)). Thus, an aqueous resin emulsion of Example 5 having a concentration of 45% by weight was obtained.

In Example 1, an aqueous resin emulsion of Example 5 was used in place of the aqueous resin emulsion of Example 1, and a method similar to that described in Example 1 was used. The glass transition temperature of the solid content of the aqueous resin emulsion was measured. Further, in Example 1,
A method described in Example 1 except that the aqueous resin emulsion of Example 5 was applied to the fiber assembly so as to obtain 6.0 g per 100 g of the fiber aggregate instead of the aqueous resin emulsion of Example 1. Using the same method as described above, a moisture absorber and a test piece for a sanitary material of Example 5 were obtained,
The specimen was evaluated. The results are shown in Table 1.

Example 6 The same procedure as in Example 1 was repeated except that the aqueous resin emulsion of Example 2 was replaced with the aqueous resin emulsion of Example 1.
After applying 5.5 g to the fiber assembly per g of the fiber assembly, 100 g of the re-emulsified powder resin (Erotex BN0107 (trade name) manufactured by Erotex Co., Ltd.) was added.
g of the water-absorbent for sanitary material of Example 6 using the same method as described in Example 1 except that the fiber aggregate was sprinkled to 2.0 g per fiber aggregate. A test piece was obtained. The test piece of Example 6 was evaluated using the same method as that described in Example 1. In the measurement of the glass transition temperature in Example 1, a re-emulsion type resin was used in the same manner as that described in Example 1 except that the re-emulsion type powder resin was used instead of the aqueous resin emulsion of Example 1. The glass transition temperature of the resin obtained from the powdered resin was measured. The results are shown in Table 1.

Example 7 In Example 1, distilled water was sprayed on the fiber assembly in place of the aqueous resin emulsion of Example 1 and then re-emulsified powder resin (Erotex BN010, manufactured by Erotex Co., Ltd.)
7 (trade name)) per 100 g of fiber aggregate.
A water absorber for a sanitary material and a test piece of Example 7 were obtained using the same method as described in Example 1 except that the fiber aggregate was sprinkled to 0 g. The test piece of Example 7 was evaluated using the same method as that described in Example 1. In addition, after adding the above-mentioned re-emulsifiable powder resin to water separately, in the measurement of the glass transition temperature of Example 1, except that it was used instead of the aqueous resin emulsion of Example 1, The glass transition temperature of the resin obtained from this re-emulsified powder resin was measured using the same method as described above. The results are shown in Table 1.

Example 8 In Example 1, an ethylene-vinyl acetate copolymer emulsion (Sumikaflex 456 (trade name), manufactured by Sumitomo Chemical Co., Ltd.) was used in place of the aqueous resin emulsion of Example 1, and the concentration was 45. % By weight) was sprayed onto the fiber assembly so as to be 4.0 g per 100 g fiber assembly, using the same method as described in Example 1 for the sanitary material of Example 8. A moisture absorber and a test piece were obtained. Example 8 Using a method similar to that described in Example 1,
Were evaluated. The method of Example 1 was repeated except that the above-mentioned ethylene-vinyl acetate copolymer emulsion was used in place of the aqueous resin emulsion of Example 1 in the measurement of the glass transition temperature of Example 1. Using the same method, the glass transition temperature of the resin obtained from the ethylene-vinyl acetate copolymer emulsion was measured. The results are shown in Table 1.

Example 9 In Example 1, styrene-butadiene rubber latex (Nippol LX430 (trade name, manufactured by Nippon Zeon Co., Ltd., concentration: 48% by weight)) was used in place of the aqueous resin emulsion of Example 1. Per 100 g of fiber aggregate,
A water absorber and a test piece for a sanitary material of Example 9 were obtained using the same method as described in Example 1 except that the fiber aggregate was sprayed to 3.5 g. The test piece of Example 9 was evaluated using the same method as that described in Example 1. A method similar to the method described in Example 1 except that the above-mentioned styrene-butadiene rubber latex was used instead of the aqueous resin emulsion of Example 1 in the measurement of the glass transition temperature of Example 1 Was used to measure the glass transition temperature of the resin obtained from this styrene-butadiene rubber latex. The results are shown in Table 1.

Example 10 241.7 g of polypropylene glycol having a molecular weight of 1000 and 62.3 g of polyethylene glycol having a molecular weight of 7500 were charged into a reactor, dissolved by heating at 95 ° C., and then 111 g of isophorone diisocyanate was added. At 95 ° C. for 6 hours to obtain a urethane prepolymer. After cooling to 50 ° C., 2.63 g of diethanolamine and 13.4 g of a nonionic emulsifier (K9 H9
60 (trade name)) and an aqueous solution containing 579.2 g of
High shear was applied to emulsify the prepolymer. further,
129.8 g of an aqueous solution containing 29.8 g of isophoronediamine was added, and a chain extension reaction was performed at 50 ° C. for 1 hour to obtain an aqueous urethane resin emulsion of Example 10 having a concentration of 40% by weight.

The procedure of Example 10 was repeated, except that the aqueous resin emulsion of Example 10 was replaced with the aqueous resin emulsion of Example 10. The glass transition temperature of the solid content of the aqueous resin emulsion was measured. Further, in Example 1, except that the aqueous resin emulsion of Example 10 was applied to the fiber aggregate so as to be 5.0 g per 100 g of the fiber aggregate in place of the aqueous resin emulsion of Example 1, Using a method similar to that described in Example 1, a water absorber and a test piece for a sanitary material of Example 10 were obtained, and the test piece was evaluated. The results are shown in Table 1.

Comparative Example 1 Comparative Example 1 was carried out in the same manner as in Example 1 except that distilled water was sprayed on the fiber assembly in place of the aqueous resin emulsion of Example 1. Thus, a moisture absorber and a test piece for a sanitary material were obtained. The test piece of Comparative Example 1 was evaluated using the same method as that described in Example 1. The results are shown in Table 1.

[0064]

[Table 1] a) The glass transition temperature of the resin obtained by drying the water-based resin emulsion and the re-emulsified re-emulsified powder resin. The unit is ° C. b) The solid content of the aqueous resin emulsion and the re-emulsifiable powder resin (that is, the total of both) is the amount present per 100 g of the fiber assembly, and the unit is g. c) Shown as the strength per 1 cm of the test piece. The value obtained by multiplying the displayed value by 10 ⁻³ is the value of the breaking strength, and the unit is N (that is, × 10 ⁻³ N). d) Glass transition temperature of aqueous resin emulsion: -5 ° C Glass transition temperature of re-emulsified powder resin: 0 ° C

[0065]

The moisture absorber for sanitary materials of the present invention is:
(A) a water absorber comprising a fiber aggregate,
Since (A) the fibers forming the fiber aggregate are bound together using a resin derived from at least one selected from (B) an aqueous resin emulsion and (C) a re-emulsifying type powder resin, The mechanical strength of the absorber, especially the mechanical strength at the time of absorbing water, is improved, and a decrease in the absorbency of the water absorber is prevented.

In the method for producing a moisture absorber for a sanitary material according to the present invention, (A) a water-based resin emulsion is applied to a moisture absorber comprising a fiber aggregate, so that a machine for the moisture absorber is used. It is possible to improve the mechanical strength, particularly the mechanical strength at the time of absorbing water, and to prevent a decrease in the absorbency of the water absorber. The method for producing a water absorber for a sanitary material according to the present invention comprises: (C) causing the re-emulsifiable powder resin to be present on the surface and / or inside of the fiber aggregate (A), and applying water to the water absorber. Can be improved, particularly the mechanical strength at the time of water absorption, and a decrease in the absorbency of the water absorber can be prevented.

The method for producing a water absorbent for sanitary materials according to the present invention comprises: (C) dispersing the re-emulsifying powder resin on the surface and / or inside of the fiber assembly; Is applied, the mechanical strength of the moisture absorber, particularly the mechanical strength at the time of absorbing water, can be improved, and a decrease in the absorbency of the moisture absorber can be prevented. Further, by the above-mentioned production method of the present invention, there is provided a moisture absorber for sanitary materials in which the mechanical strength, particularly the mechanical strength at the time of absorbing water, is improved and the absorption of the moisture absorber is prevented from being reduced.

Further, by using the above-mentioned moisture absorber for a sanitary material, the shape of the moisture absorber is broken or broken by its own weight, so that between the breathable polymer sheet and the nonwoven fabric inside the sanitary material. The problem of the occurrence of the failure of the sanitary material due to the movement of the absorbent and the uneven distribution of the absorbent inside the sanitary material, and as a result, the partial decrease in the absorbency of moisture is reduced or eliminated. Provide sanitary materials.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C09K 3/00 (72) Inventor Toshinari Yamamoto 3-7-46 Funaba Nishi, Minoh-shi, Osaka F-term (Reference) 3B029 BA12 BA17 4C003 AA07 AA12 AA22 AA27 GA02 4C098 AA09 CC40 DD05 DD06 DD14 DD23 DD27 4L047 AA08 AB02 BA13 BA17 BC05 BC14 CA19 CB01 CB07 CC03 CC04 CC05

Claims (6)

[Claims] 1. A water absorber comprising (A) a fiber assembly, wherein (A) the fibers forming the fiber assembly are composed of (B) an aqueous resin emulsion and (C) a re-emulsified powder. A water absorber for a sanitary material, wherein the water absorber is bonded using a resin derived from at least one selected from resins. 2. A method for producing a water absorber comprising (A) a fiber assembly, wherein (A) an aqueous resin emulsion is applied to the (A) fiber assembly. Method for producing a water absorber. 3. A method for producing a water absorber comprising (A) a fiber aggregate, wherein (C) the re-emulsifiable powder resin is present on (A) the surface and / or inside the fiber aggregate. ,
A method for producing a water absorber for sanitary materials, characterized by applying water. 4. A method for producing a water absorber comprising (A) a fiber aggregate, wherein (C) the re-emulsifying powder resin is present on (A) the surface and / or inside of the fiber aggregate. ,
(B) A method for producing a water absorber for sanitary materials, characterized by applying an aqueous resin emulsion. 5. A moisture absorber for a sanitary material, which is produced by the production method according to claim 2. Description: 6. A sanitary material using the water absorber for a sanitary material according to claim 1.