JPH10211234A - Article for absorbing body fluid - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an article for absorbing body fluid which is superior in a shape holding performance in being wet and fluid leakage prevention performance by setting a moist shape holding rate of a fluid absorbing complex to a specific value in a body fluid absorbing article in which the compressed fluid absorbing complex having fluid absorbing polymer and a base material for supporting it. SOLUTION: In an article for absorbing body fluid which is formed by, at least, partially arranging compressed fluid absorbing complex having, at least, fluid absorbing polymer and a base material for supporting it, a moist shape holding rate of the fluid absorbing complex is set to 10% or more. The compression elastic ratio of the base material is set to 3 or more and a polyurethane sponge base material is used as the base material. The bending resistance of the base material is set to 2000(mgf) N} or less and a substance obtained by polymerizing water soluble unsaturated monomer on the base material is set as the fluid absorbing complex. The fluid absorbing complex is compressed by adding a water soluble binder and this compressed fluid absorbing complex is arranged in the circumference of an absorbing core as a fluid leakage preventing material.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a body fluid absorbing article having a liquid-absorbing composite at least partially arranged. Furthermore, to be more specific, the liquid-absorbing composite, which is particularly excellent in shape retention when wet, is at least partially arranged.
The present invention relates to a body fluid absorbing article such as a disposable diaper, a sanitary napkin, an incontinence pad and the like.

[0002]

2. Description of the Related Art In recent years, a superabsorbent resin having high water absorbency has been developed and is composited with a fiber base such as cotton, pulp, paper and sponge, and has been put to practical use as a body fluid absorbing article such as a disposable diaper or a sanitary napkin. Has been For example, Japanese Patent Application Laid-Open No.
No. 3562 discloses that a water-absorbent polymer is bonded to a fiber web having compression-restoring elasticity, and a second layer made of hydrophilic fibers is pressed in the thickness direction under wet conditions to form a fiber. It is disclosed to obtain a web compression composite. This compressed composite has a problem that the water absorption rate is low and the lateral leakage (re-wet, return amount) increases. Therefore, as a means for improving this, a hydrophilic low-density fiber layer (crushed pulp) is added to the compressed composite. Lamination has also been proposed.

[0003] However, this compressed composite has a small restorability when deformed by the wearer's walking or rolling motion, and has a problem in shape retention. It was almost impossible to hold, and liquid leakage was easy to occur.

[0004]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a body fluid absorbing article which has a high liquid absorption rate and a small amount of return, and is particularly excellent in shape retention and liquid leakage prevention when wet. It is in.

[0005]

According to the present invention, a compressed liquid-absorbing composite having at least a liquid-absorbing polymer and a substrate supporting the liquid-absorbing polymer is at least partially arranged. Provided is a body fluid absorbing article, characterized in that the liquid absorbent composite has a wet shape retention ratio of 10% or more.

The present invention also provides the above-mentioned body fluid absorbing article, wherein the compression elasticity ratio of the substrate is 3 or more. The present invention further provides the above body fluid absorbing article, wherein the substrate is a polyurethane sponge substrate. The present invention also provides the above-mentioned body fluid absorbing article, wherein the base material has a stiffness of 2000 (mgf) {N} or less.

The present invention further provides the above-mentioned body fluid absorbing article, wherein the liquid-absorbing complex is obtained by polymerizing a water-soluble unsaturated monomer on a substrate. The present invention also provides
The present invention provides the above-mentioned body fluid absorbing article, wherein the liquid-absorbing composite is a product obtained by adding a water-soluble binder and compressing the composite. The present invention further provides the above-mentioned body fluid absorbing article, wherein the liquid-absorbent composite is disposed around the absorbent core as a liquid leakage preventing material.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.
The absorbent composite used in the body fluid absorbing article of the present invention is
Has a specific wet shape retention. The method of measuring the wet shape retention ratio is as shown in the examples, and indicates that the higher the value of the wet shape retention ratio, the more easily the liquid-absorbent composite deformed after liquid absorption is restored to its original form. I have. The liquid absorbent composite used in the present invention has a wet shape retention of 10% or more, preferably 6%.
0% or more, more preferably 95% or more. 10%
When the value is less than the above, the body fluid absorbing article is less resilient when deformed by the wearer's walking or rolling motion, and is likely to cause lateral leakage, and in particular, liquid leakage after liquid absorption and wetting increases.

The absorbent composite used in the present invention is compressed, and it is preferable to maintain the compressed state until the first liquid absorption occurs. Maintaining the compressed state means that there is substantially no change in the thickness from the compressed state until the first liquid absorption occurs, and refers to maintaining the thickness of 60% or less of the thickness before compression. . Since the thickness of the liquid-absorbent composite is reduced by such compression, a thin product can be obtained when a product such as a disposable diaper or a napkin is formed. In addition, the density of the liquid-absorbent composite obtained by compression increases, and "strain" appears in the texture, so that it is excellent in shape retention and prevents kinking.

[0010] In the case of products such as disposable diapers and napkins, it is better to compress the product in terms of thinness. However, if the product is too compressed, it will be too hard and the texture of a product such as a diaper will be impaired. Therefore, the degree of compression is generally set to a thickness in the range of 2/3 to 1/100 of the normal thickness. In particular, the range of 1/2 to 1/10 is preferable.

The method for compressing the liquid-absorbent composite includes: (1) a method for compressing the obtained liquid-absorbent composite. If necessary, the liquid-absorbing polymer fixing the obtained liquid-absorbing composite to the substrate may be softened with water, a water-soluble bonding agent may be used, or compressed while heating. In addition, a known method can be adopted as the compression method, but a method of winding with a strong tension and compressing with a winder is preferable from the viewpoint of productivity and workability. (2) A method of producing a liquid-absorbent composite using the compressed base material by compressing the base material before polymerization to make it thinner. (3) A method in which, when a water-soluble unsaturated monomer that can be converted into a liquid-absorbing polymer by polymerization is polymerized on a substrate, the substrate to which the monomer is attached is compressed. (Simultaneous polymerization and compression) (4) A method of compressing a substrate to which the water-soluble polymer or the like has adhered when the water-soluble polymer or the like is adhered to the substrate and cross-linked on the substrate. (Simultaneous crosslinking and compression).

Above all, in the method of compressing the monomer while polymerizing it on the base material, the resulting liquid-absorbing polymer itself serves as a bonding agent, so that the compressed shape can be maintained without using another bonding agent. . Therefore, the polymerization and compression steps can be performed in one step, and excellent liquid-absorbing swelling properties are exhibited because no other bonding agent that inhibits liquid-absorbing swelling is used. For this reason, the method of compressing the monomer while polymerizing it on the substrate is most preferable. When the compressed liquid-absorbent composite comes into contact with water, the compressed form is released due to the liquid-absorbent swelling of the liquid-absorbent polymer, and the composite expands in volume.

In the method of compressing a water-soluble polymer or the like while crosslinking it on a substrate, the liquid-absorbing polymer itself produced by the crosslinking serves as a bonding agent and maintains a compressed shape. Therefore, the step of forming the liquid-absorbent polymer by crosslinking and the compression step can be performed in one step. In addition, since no other bonding agent is used, excellent liquid swelling property is exhibited. For this reason, a method of compressing while crosslinking a water-soluble polymer or the like is also preferable.

Further, by applying a water-soluble binder and compressing the binder, the bonding force of the binder contributes to maintaining the compressed form, and it is easy to control the degree of compression to an optimum degree. In addition, since the water-soluble binder becomes water-soluble during liquid absorption, it does not hinder the liquid-absorbing swellability of the liquid-absorbing composite. Examples of the method of applying the water-soluble binder to the liquid-absorbing composite include impregnation, spraying, coating, and spraying the liquid-absorbing composite.
A method in which the monomer is previously contained in a water-soluble unsaturated monomer and the monomer is polymerized on a substrate is also simple and preferable.

The amount of the water-soluble binder to be applied (active ingredient) is preferably 0.1 to 40 parts by weight, more preferably 5 to 20 parts by weight, based on 100 parts by weight of the dry absorbent composite. Parts by weight. If the amount is less than 0.1 part by weight, the binder effect may be insufficient and compression may be difficult. On the other hand, when the amount exceeds 40 parts by weight, the liquid absorbing property of the liquid absorbing composite at the time of liquid absorption may be adversely affected, and problems in workability and economy are likely to occur.

Examples of the water-soluble binder include dextrin, gum arabic, methyl cellulose, urea-based initial condensate, water-soluble phenol resin, polyvinyl methyl ether, polyvinyl alcohol, starch, glue, casein, shellac, hydroxyethyl cellulose, and polyacrylic acid. Examples include water-soluble resins such as sodium, polydioxolan, and polyethylene oxide, and water-soluble thermoplastic resins. Above all, polyvinyl alcohol, starch, and hydroxyethyl cellulose are preferable from the viewpoint of water solubility, and further, water-soluble thermoplastic resins such as polydioxolane and polyethylene oxide need to be dissolved in a solvent such as water because they can be melted by heating. This is particularly preferable because the step of removing the solvent after application can be omitted.

An organic solvent or an emulsion-type binder may be used as long as the amount does not impair the liquid absorbing property. Nitrate cellulose, acetate cellulose, ethyl cellulose, polyvinyl acetate, polyvinyl butyral, polystyrene ,
Natural rubber, synthetic rubber, butyl rubber, vinyl chloride-vinyl acetate copolymer, polyacrylate and the like can be mentioned.

The liquid-absorbent composite used in the present invention preferably releases the above-mentioned compressed state and swells when the first liquid absorption occurs. In other words, the liquid-absorbent composite is compressed and thin, and maintains its compressed state until the first liquid absorption occurs. Swells up to the thickness of. The degree of swelling is preferably 1.5 times or more, more preferably 2 times or more, the thickness at the time of compression. 1.5
If it is less than twice, liquid leakage is likely to occur.

The above-mentioned liquid-absorbing composite will be described more specifically. The liquid-absorbent composite used in the present invention includes at least a liquid-absorbent polymer and a substrate supporting the polymer. Examples of such a liquid-absorbing composite include the following types. A) a liquid-absorbent composite obtained by coating at least a part of the liquid-absorbent polymer with a substrate such as a water-permeable nonwoven fabric or sponge; B) A liquid-absorbing composite obtained by directly pressing a liquid-absorbing polymer softened with a solvent such as water on a substrate such as a nonwoven fabric or a sponge, and drying as necessary. C) A liquid-absorbing composite obtained by attaching a liquid-absorbing polymer to a substrate such as a nonwoven fabric or a sponge using a bonding agent. D) A liquid-absorbing composite obtained by applying a water-soluble polymer such as sodium polyacrylate, polyvinyl alcohol, and polyalkylene glycol, which can be converted to a liquid-absorbing polymer, to a substrate, followed by crosslinking. E) A liquid-absorbing composite obtained by applying a water-soluble unsaturated monomer such as a metal acrylate monomer, which can be converted into a liquid-absorbing polymer by polymerization, to a base material and then polymerizing the base material. And the like.

Above all, from the viewpoints of swelling property, durability, easiness of production and economical efficiency, a monomer which can be converted into a liquid-absorbing polymer by polymerization is adhered to a substrate, and then the monomer is placed on the substrate. The liquid-absorbing composite obtained by polymerization in the above is preferable.
Examples of the substrate used for the liquid-absorbent composite include porous materials such as hydrophilic or hydrophobic woven fabric, nonwoven fabric, paper, knitted fabric, and sponge. It is preferable that the base material has voids therein, because a space allowing swelling of the liquid-absorbing polymer can be secured, and water or the like can effectively contact the liquid-absorbing polymer. The shape is preferably a sheet or a tape from the viewpoint of handleability.

As the material used as the base material, when the base material is a fiber base material, as the hydrophilic material, wood pulp,
Fibers such as cotton, wool, rayon, acetate, vinylon, etc. are listed, and hydrophobic ones include fibers such as polyester, acrylic, nylon, polypropylene, polyethylene, polyurethane, glass wool, rock wool, metal fibers (metal wool), and shapes. Memory alloy fibers can be mentioned.

When the substrate is in the form of a sponge, polyurethane sponge, cellulose sponge, viscose sponge, polyvinyl alcohol sponge, polyethylene foam, polypropylene foam, rubber sponge, polyvinyl acetal sponge, polyacetal sponge Sponge, phenol resin sponge, metal sponge and the like can be mentioned.

Further, a composite of two or more of the above-mentioned substrates can also be used. Further, the above-mentioned colored or flame-retardant base material can also be used. Above all, the obtained liquid-absorbent composite retains the liquid-absorbing swellability (expandability) and the expanded form,
From the viewpoint of preventing liquid leakage, a sponge substrate having high compression recovery elasticity is preferable, and among them, a polyurethane-based sponge substrate is preferably used from the viewpoint of the shape retention ratio before liquid absorption and the wet shape retention ratio.

The sponge substrate has voids of open cells and a large surface area in contact with water, so that the liquid absorbing composite obtained has a high liquid absorbing speed. In addition, due to the combination of the bubble space and the liquid-absorbing swelling property of the liquid-absorbing polymer, extremely high retention of liquid such as water is exhibited. Therefore, when a sponge substrate is used, extremely high liquid absorption swelling property is exhibited. In addition, by using a base material having high compression restoring elasticity, the liquid-absorbing composite has a very rapid volume expansion due to liquid absorbing swelling due to a high liquid-absorbing swelling property and a restoring elasticity of the base material when a liquid is added. Is expressed. The speed of the volume expansion is, when immersed in water, the time required to reach a thickness of 90% of the maximum expansion thickness is within 10 minutes, preferably within 5 minutes, more preferably within 2 minutes. . If the swelling time is longer than 10 minutes, the liquid leakage prevention property is reduced. And
After swelling once, even if deformed, it is easy to restore to its original form.

The substrate used in the present invention is preferably one having high compression restoring elasticity as described above.
Specifically, those having a compression elasticity ratio of 3 or more, preferably 5 or more, described below are suitably used. When the compression elasticity ratio is less than 3, the obtained liquid-absorbent composite cannot sufficiently maintain the expanded form. Here, the compression elasticity ratio was determined by the following equation.

Compression elasticity ratio = (T2−T1) / T1 T1: Thickness when 15 substrates are stacked and a load of 10 kgf / 20 cm ² is applied for 1 minute T2: The load is removed after T1 measurement and left for 1 minute , 30
Thickness when a load of gf / 20 cm ² is applied for 1 minute The thickness of the substrate used in the present invention in a normal state is not particularly limited, but is generally in the range of 0.2 mm to 100 mm, and particularly 2 mm to 10 mm. Is preferred. 0.2mm
If it is less than 10 mm, the resulting liquid-absorbent composite may have reduced swellability and material strength due to liquid absorption swelling, and if it exceeds 100 mm, handling becomes complicated.

Since the body fluid absorbing article of the present invention comes into direct contact with the human body, the base material of the absorbent composite has a stiffness of 2000 (mgf) {N} or less, preferably 200 or less. (Mgf) It is preferable to use a soft material of {N} or less. If the bending resistance exceeds 2,000 (mgf) {N}, the resulting liquid-absorbent composite will have a hard feel and will be difficult to handle, and it will be difficult to produce (polymerize) the liquid-absorbent composite. The bending resistance is measured according to JIS-L1096.

The liquid-absorbing polymer to be fixed to the substrate is, for example, water-soluble ethylene containing acrylic acid or an acrylate or a sulfonic acid group-containing acrylate as a main component and optionally adding a crosslinking agent. 10 to 100 of its own weight obtained by polymerizing the unsaturated monomer.
Water-absorbing polymers that absorb and swell 0-fold water can be mentioned, and are preferably used.

As examples other than the above liquid absorbing polymer,
For example, crosslinked polydioxolane, crosslinked polyethylene oxide, crosslinked polyvinylpyrrolidone, crosslinked sulfonated polystyrene, crosslinked polyvinylpyridine, saponified starch-poly (meth) acrylonitrile graft copolymer, starch-poly (meth) acrylic acid (and Examples thereof include water-absorbing polymers such as a salt thereof, a graft crosslinked copolymer, a reaction product of polyvinyl alcohol and maleic anhydride (salt), a crosslinked polyvinyl alcohol sulfonate, and a polyvinyl alcohol-acrylic acid graft copolymer.

Further, as the liquid-absorbing polymer other than the above-mentioned water-absorbing polymer, the following monomers are used as main components, and a crosslinking agent is added as needed. An oil-absorbing polymer having an absorption capacity can be mentioned. For example, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, iso-butyl (meth) acrylate, t-butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-octyl (meth) acrylate, dodecyl (meth) acrylate, stearyl (meth) acrylate, phenyl (meth) acrylate, octylphenyl (meth) acrylate, nonylphenyl (meth) acrylate, dinonylphenyl (meth) acrylate, cyclohexyl ( (Meth) acrylate, menthyl (meth) acrylate, polyalkylene glycol mono (meth) acrylate, alkyl polyalkylene glycol mono (meth) acrylate, poly (di) alkylsiloxane mono ( Data) acrylate, isobornyl (meth) acrylate ,, dibutyl maleate, didodecyl maleate, dodecyl crotonate, unsaturated carboxylic acid esters such as didodecyl itaconate; (di) butyl (meth) acrylamide,
(Meth) having a hydrocarbon group such as (di) dodecyl (meth) acrylamide, (di) stearyl (meth) acrylamide, (di) butylphenyl (meth) acrylamide and (di) octylphenyl (meth) acrylamide
Acrylamide; α-olefins such as 1-hexene, 1-octene, isooctene, 1-nonene, 1-decene and 1-dodecene; alicyclic vinyl compounds such as vinylcyclohexane; allyl having a hydrocarbon group such as dodecyl allyl ether Ethers; vinyl esters having a hydrocarbon group such as vinyl caproate, vinyl laurate, vinyl palmitate and vinyl stearate; vinyl ethers having a hydrocarbon group such as butyl vinyl ether and dodecyl vinyl ether: styrene, t-butyl styrene, octyl styrene And the like.

The liquid-absorbing composite in which two or more of the above-mentioned water-absorbing polymer and oil-absorbing polymer are mixed can absorb liquid irrespective of hydrophilic or hydrophobic liquid, and has excellent liquid-absorbing swelling property. Is shown. In the present invention, the weight ratio of the liquid-absorbent polymer to the substrate is preferably in the range of 10 to 1000 parts by weight with respect to 100 parts by weight of the substrate. When the amount of the liquid-absorbing polymer is less than 10 parts by weight, the liquid-absorbing swelling property is reduced. On the other hand, when the amount is more than 1000 parts by weight, the polymer is desorbed from the substrate of the liquid-absorbing composite. However, the flexibility is lowered, which is not preferable from the viewpoint of workability.

After adhering a monomer capable of being converted into a liquid-absorbing polymer by polymerization to a substrate, the liquid-absorbing complex obtained by a method of polymerizing the monomer on the substrate is subjected to liquid absorption as described above. It is preferable from the viewpoints of swellability, durability, ease of production, and economy, and has the following effects. (1) It exhibits high liquid absorption swelling because it does not use a binder such as an adhesive, a pressure-sensitive adhesive, or rubber that inhibits liquid absorption swelling. (2) Since the liquid-absorbing polymer is directly and firmly fixed to the base material itself, the polymer does not fall off very little and does not contaminate the periphery. (3) Since it is in the form of a sheet, it is easy to handle, some processing and construction work is simple, and disposal and removal after use are easy. (4) Since the monomer is directly attached to the base material by impregnation or the like, the polymer can be uniformly formed on the entire base material (surface and inside). Therefore, the liquid-absorbing swelling is uniform and shows high liquid-absorbing swelling.

Specific examples of the monomer to be attached to the substrate include, for example, acrylic acid, methacrylic acid, itaconic acid,
Maleic acid, fumaric acid, crotonic acid, citraconic acid,
Vinylsulfonic acid, (meth) allylsulfonic acid, 2-
(Meth) acrylamide-2-methylpropanesulfonic acid, 2- (meth) acryloylethanesulfonic acid, 2-
(Meth) acryloylpropanesulfonic acid, (meth) allylsulfonic acid, and their alkali metal salts and ammonium salts; N, N'-dimethylaminoethyl (meth) acrylate and its quaternary product, (meth) acrylamide, N , N'dimethyl (meth) acrylamide,
2-hydroxyethyl (meth) acrylamide, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, hydroxyalkyl (meth) acrylate, polyethylene glycol mono (meth) acrylate, polyalkylene glycol ( Meth) acrylates, and one or two of these
More than one species can be used.

From the viewpoint of the swelling property of the absorbent composite, acrylic acid, methacrylic acid, and their alkali metal salts and ammonium salts are preferably used. Further, in order to maintain a high liquid absorption swelling over a long period of time, a monomer capable of obtaining a salt-resistant or nonionic liquid-absorbing polymer by polymerization, acrylic acid, methacrylic acid, and,
It is particularly preferred to copolymerize these alkali metal salts and ammonium salts.

Examples of the salt-resistant or nonionic monomer include 2- (meth) acryloylethanesulfonic acid and 2
-(Meth) acryloylpropanesulfonic acid, 2- (meth) acrylamido-2-methylpropanesulfonic acid and water-soluble ethylenically unsaturated monomers having a sulfonic acid group such as alkali metal salts and ammonium salts thereof,
(Meth) acrylamide such as (meth) acrylamide, (meth) acryloylmorpholine, diacetone (meth) acrylamide, N-isopropyl (meth) acrylamide, N, N'-dimethyl (meth) acrylamide and derivatives thereof; polyethylene glycol (meth) Polyalkylene glycol (meth) acrylate represented by acrylate or methoxypolyethylene glycol (meth) acrylate; hydroxyalkyl (meth) acrylate represented by hydroxyethyl (meth) acrylate or hydroxypropyl (meth) acrylate; N-vinyl N-vinyl monomers represented by pyrrolidone and N-vinylsuccinimide; N-vinylformamide, N-vinyl-N-methylformamide, N-vinylacetamide, N-vinyl N-vinylamide monomers such as -N-methylacetamide: vinyl methyl ether and the like.

Among them, one or more selected from acrylamide, methacrylamide, methoxypolyethylene glycol (meth) acrylate, and hydroxyalkyl (meth) acrylate are preferably used. The monomer to be adhered to the base material may be used as a 100% component or in the form of an aqueous solution. The monomer concentration when handled as an aqueous solution is preferably in the range of 2% by weight or more and less than 90% by weight, more preferably 20% by weight.
% By weight or more and less than 50% by weight. When the amount is less than 2% by weight, the polymerizability is reduced, and when the amount is more than 90% by weight, the liquid-absorbing swellability of the obtained liquid-absorbing composite is reduced.

If necessary, the aqueous monomer solution may contain:
A crosslinking agent, a polymerization initiator, a thickener such as hydroxyethylcellulose, and additives such as a water-soluble polymer, a liquid-absorbing polymer powder, and a moisture-absorbing / wetting agent may be added. The aqueous monomer solution may be one in which a small amount of a water-soluble organic solvent is dissolved. In particular, it is preferable to add a water-absorbing polymer powder since the resulting liquid-absorbing composite has improved liquid-absorbing swellability. From the viewpoint of the liquid absorption swelling property and the mixing property with the monomer, those having a particle size of 150 μm or less, more preferably 75 μm or less, are suitably used.

As the cross-linking agent, a copolymerizable polyfunctional water-soluble or oil-soluble ethylenically unsaturated monomer or a compound capable of reacting with a functional group of the monomer can be used. It can be added to the above monomer, previously applied to a substrate and adhered thereto, or added after polymerization. Specific examples of the crosslinking agent include N, N'-methylenebis (meth) acrylamide and ethylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, polyalkylene glycol, Examples include polyalkylene glycol diglycidyl ether, polyhydric alcohol, polyvalent epoxy compound, polyvalent amine, alkylene carbonate, divinylbenzene, and the like.

The use of the crosslinking agent can improve the durability, shape retention and swelling of the resulting absorbent composite. The amount of the cross-linking agent can be appropriately selected depending on the type of the monomer and the polymerization conditions.
It is in the range of 1 to 10 mol% (relative to monomer), preferably in the range of 0.01 to 5 mol% (relative to monomer). If the amount is less than 0.001 mol%, the liquid-absorbing polymer may be detached from the substrate, and if it is more than 10 mol%, the liquid-absorbing swellability and the polymerizability are undesirably reduced.

In order to promote the polymerization, it is preferable to use a polymerization initiator. The polymerization initiator used in the present invention is an oxidizing or azo radical polymerization initiator which is water-soluble or water-miscible / dispersible with water, and one or more of these initiators may be used. Further, a redox initiator may be used by adding a reducing substance. Furthermore, the azo initiator, the oxidizing initiator and the reducing substance may be combined to form a ternary initiator, which is particularly preferable from the viewpoints of polymerizability and swelling property.

A method in which an azo-based initiator and an oxidizing initiator are added to a monomer and adhered to a substrate and then a reducing substance is added has good stability of the monomer and is easy to handle. Further, the monomer and the above three components may be mixed and sprayed on the base material immediately before being attached to the base material using a screw nozzle. Examples of the oxidative polymerization initiator include persulfates such as sodium persulfate, potassium persulfate and ammonium persulfate; inorganic peroxides such as hydrogen peroxide; organic peroxides such as di-tert-butyl peroxide and acetyl peroxide. No.

As the azo polymerization initiator, 2,2′-azobis (2-amidinopropane) dihydrochloride, 2,2′-
Azobis (N, N 'dimethyleneisobutylamidine) 2
Hydrochloride, 4,4′-azobis (4-cyanovaleric acid),
An azo compound such as 2,2′-azobis (2,4-dimethylvaleronitrile) can be given. Examples of the reducing substance include a sulfite, L-ascorbic acid, an amine and the like. The reducing substance forms an oxidation-reduction system with the oxidizing polymerization initiator and promotes its decomposition. This is known as a redox initiator.

The amount of the polymerization initiator to be added is generally from 0.001 g / mol to less than 10 g / mol with respect to the monomer, but from the viewpoints of polymerizability, economy and discoloration, 0.1 g / mol.
/ Mol or more and less than 5 g / mol. When the amount is less than 0.001 g / mol, the polymerizability is reduced and a large amount of unreacted monomers may remain. When the amount is more than 10 g / mol, the liquid-absorbing swellability of the obtained liquid-absorbing polymer sheet is reduced. However, there is also a problem in economics.

As a method for adhering the monomer to the substrate, any known means can be used as long as the monomer can be uniformly or desirably dispersed and maintained on the substrate and polymerized. Specifically, it means impregnating, spraying, coating or printing a substrate with an aqueous monomer solution. Further, if necessary, after spraying, impregnating, coating or printing, it can be squeezed out with a roller or the like to control the amount of monomer adhesion. The aqueous monomer solution can adhere to the entire surface of the substrate, or can adhere to only one surface. A concentration gradient can be given in the thickness direction of the substrate. Also,
The monomer aqueous solution can be attached in a dot, stripe, lattice, or other pattern.

The monomer adhered to the substrate is polymerized by a known means, and the liquid-absorbing polymer can be directly fixed to the substrate.
As a method of polymerizing a monomer, for example, heat, light, γ
A method using a beam, an electron beam, an ultraviolet ray, a microwave, or the like can be employed. Above all, from the viewpoints of compression processability, productivity, and polymerizability, a method in which the base material to which the monomer is attached is sandwiched while being pressed with an inert belt and heated and polymerized is preferred.

The thickness of the liquid-absorbent composite used in the present invention is preferably as thin as possible in order to improve the handleability. The thickness of the liquid-absorbent composite used in the present invention is in the range of 0.1 mm or more and less than 10 mm, 0.2 mm
To 5 mm is preferred. If it is less than 0.1 mm, the liquid absorption swelling property is reduced, and if it is 10 mm or more, the handling property is reduced, and the work, storage and transportation during processing and construction are undesirably complicated.

The liquid-absorbing complex thus obtained is
It can be used alone, but it is possible to apply a pressure-sensitive adhesive or adhesive to at least a part of the composite, or to composite with a nonwoven fabric, film, pulp, etc. as long as the liquid absorption swelling property of the sheet is not impaired, and process and manufacture a body fluid absorbing article May be. The body fluid absorbing article of the present invention has the above-described liquid-absorbing complex at least partially disposed therein. As with the conventional liquid-absorbent composite, the liquid-absorbent composite may be sandwiched between a liquid-permeable top sheet and a liquid-impermeable backsheet to form an absorbent core, or a strip-shaped absorbent core may be provided around the absorbent core. The liquid composite may be disposed as a liquid leakage preventing material. Since the liquid-absorbent composite has a high shape retention ratio and a wet shape retention ratio, it exhibits excellent liquid leakage prevention properties. It is particularly effective for preventing loose stools from leaking in newborns.

The body fluid that can be absorbed by the body fluid absorbing article of the present invention includes urine, blood, loose stool, sweat, lymph, saliva and the like.

[0049]

Next, the present invention will be described in more detail with reference to examples. The absorption time, return amount, shape retention, wet shape retention, and liquid leakage were measured by the following methods. (Absorptive liquid) Sheep blood "SHEEP defibrinated blood" manufactured by Japan Biotest Laboratory Co., Ltd. was used. (Absorption time) After 5 mL of sheep blood was added to the center of a 7 * 7 cm sample with a syringe, the time [sec] until absorption of sheep blood from the sample surface due to absorption was measured. (Return amount) 5 mL of sheep blood was added to the center of a 7 * 7 cm sample using a syringe, and after standing for 5 minutes, 18 g of paper (Kim towel, manufactured by Jujo Kimberly Co., Ltd.) was placed on the surface of the sample for 1 minute. When a load of ² kg / cm ² was applied, the amount of sheep blood absorbed and returned to the paper was calculated from the weight change of the paper. (Shape retention ratio) A 7 * 7cm sample before liquid absorption was folded in ^{two and} a load of 0.2kg / cm2 was applied for 1 minute. Then, the sample was removed and the sample was hung for 10 seconds with one corner of the sample removed. Was. Next, it was gently placed on a horizontal base and the straight-line distance between both ends of the bent side was measured. The value of the distance is the length of the original side (7c
m) to obtain the shape retention ratio. (Wet shape retention) 7 * 7cm after measurement of absorption time and return amount
After folding the sample in half and applying a load of 0.2 kg / cm ² for 1 minute, remove the load and hold one corner of the sample,
Hanged for 0 seconds. Next, it was gently placed on a horizontal base and the straight-line distance between both ends of the bent side was measured. The value of the distance was divided by the length of the original side (7 cm) to obtain a wet shape retention ratio. (Amount of liquid leakage) (1) Cut the center of the absorber (absorber core) of Kao's paper diaper “Meries” into a size of 7 cm × 10 cm.

(2) The absorber is placed on a smooth plate plate, and the width 1c is set so as to be in contact with the peripheral portion (four sides) of the absorber.
A liquid-absorbent composite of m * 10 cm is arranged as a liquid leakage prevention material. (3) Add 180 g of 0.9% aqueous sodium chloride solution to the absorbent body with a syringe. (4) Measure the amount of physiological saline leaking (liquid leakage [g]). (Production Example 1 of Liquid Absorbent Complex) N, N'-methylenebisacrylamide 0.1 was added to a partially neutralized aqueous solution of sodium acrylate in which 99 mol% was neutralized with sodium hydroxide.
Mole% (based on monomer), 1.5% by weight of hydroxyethyl cellulose (based on monomer) and 1.0 g / mole of sodium persulfate (based on monomer) and 2,2'-azobis
(N, N 'dimethyleneisobutylamidine) dihydrochloride
5 g / mol (relative to the monomer) was dissolved to prepare a 34% by weight aqueous monomer solution.

Next, a compressive elasticity ratio of 10, an elasticity of 20 (mgf) {N} and a thickness of 4.6 m were added to the aqueous monomer solution.
After immersing a polyurethane sponge substrate having a m and a basis weight of 72 g / m ² and impregnating the aqueous solution, excess monomer aqueous solution was squeezed out with a roller. This impregnated material was sandwiched between two inert belts and subjected to radical polymerization by heating while being compressed on the substrate.

The obtained composite had a liquid absorbing polymer of 150 g / m ² fixed directly to the substrate and had a thickness of 1 mm. A surfactant is attached to this complex to form an absorbent composite.
(1) was obtained. (Production Example 2 of Liquid Absorbent Composite) Radical polymerization by heating was performed on a substrate without compressing the monomer-impregnated product of Production Example 1. The obtained composite was sandwiched between two metal rollers and crushed under the condition of zero clearance.

In this composite, 151 g / m ² of the liquid-absorbing polymer was directly adhered to the substrate, the thickness was 1 mm, and it was thin and much more flexible than before crushing. A surfactant was attached to this complex to obtain a liquid-absorbing complex (2). The thickness after standing for 3 months was 1.5 mm. (Production Example 3 of Liquid Absorbent Composite) The monomer-impregnated product of Production Example 1 was subjected to heating radical polymerization on a substrate without compression. The poly (dioxolane) powder was uniformly spread on the obtained sheet-like composite, and was hot-pressed and crushed while heating.

In this composite, 150 g / m ² of the liquid-absorbing polymer was directly adhered to the base material, the thickness was 1 mm, the thickness was thin, and it was much more flexible than before crushing. A surfactant was attached to this complex to obtain an absorbent composite (3). The thickness after standing for 3 months was 1 mm, and there was no change with time, and it was extremely stable. (Example 1) 1 mm thick cut into 7 cm * 7 cm
Sheep blood was poured into the central part of the liquid-absorbent complex (1) using a syringe, and the absorption time, return amount, shape retention ratio before liquid absorption, and wet shape retention ratio were measured.

The absorption time of the liquid-absorbent composite (1) was 60 seconds, the amount of reversion was 1.6 g, and the shape retention ratio before liquid absorption was almost 100%. In addition, the shape retention ratio after liquid absorption was almost 100%, and almost the original state was restored. The liquid-absorbent composite (1) had a small thickness before liquid absorption and was easy to handle. further,
Even if the liquid-absorbent composite (1) expanded in the thickness direction after liquid absorption was deformed by pressing it with a finger, the composite was immediately restored to its original state, and the expanded form was maintained. (Example 2) Absorbent composite (2) instead of absorbent composite (1)
The procedure was performed under the same conditions as in Example 1 except for using.

The absorption time of the liquid-absorbent composite (2) was 62 seconds, the amount returned was 1.7 g, and the shape retention ratio before liquid absorption was almost 100%. In addition, the shape retention ratio after liquid absorption was almost 100%, and almost the original state was restored. The liquid-absorbent composite (2) had a small thickness before liquid absorption and was easy to handle. further,
Even if the liquid-absorbent composite (2) expanded in the thickness direction after liquid absorption was deformed by pressing it with a finger, it was immediately restored to its original state, and the expanded state was maintained. (Example 3) Instead of the absorbent composite (1), the absorbent composite (3)
The procedure was performed under the same conditions as in Example 1 except for using.

The absorption time of the liquid-absorbent composite (3) was 65 seconds, the amount of return was 1.8 g, and the shape retention ratio before liquid absorption was almost 100%. In addition, the shape retention ratio after liquid absorption was almost 100%, and almost the original state was restored. In addition, the liquid-absorbent composite (3) was thin and easy to handle before liquid absorption. further,
Even if the liquid-absorbent composite (3) expanded in the thickness direction after liquid absorption was deformed by pressing it with a finger, it was immediately restored to its original state, and the expanded form was maintained. (Comparative Example 1) The same operation as in Example 1 was performed except that a commercially available absorbent core (Whisper Ultra Slim) for a disposable diaper was used as the comparative liquid absorbent composite (1) instead of the liquid absorbent composite (1). Was.

The absorption time of the comparative liquid-absorbent complex (1) was 300
Seconds, the return amount was 2.6 g, and the shape retention ratio before liquid absorption was 75%. In addition, the shape retention rate after liquid absorption was 0%, and the original state was not restored at all. In addition, the expanded liquid-absorbing complex after liquid absorption (1)
When pressed with a finger, it was easily deformed and did not return to its original state at all. (Comparative Absorbent Composite Production Example 1) N, N'-methylenebisacrylamide 0.1 mol% (based on monomer) was added to a partially neutralized aqueous solution of sodium acrylate in which 99 mol% was neutralized with sodium hydroxide. 1.5% by weight of hydroxyethyl cellulose (based on monomer) and 1.0 g / mole of sodium persulfate (based on monomer) and 0.5 g / mole of 2,2′-azobis (N, N ′ dimethyleneisobutylamidine) dihydrochloride (To the monomer) was dissolved to prepare a 34% by weight aqueous monomer solution.

Next, a rigidity of 18 was added to the aqueous monomer solution.
After dipping a cellulose sponge sheet of 000 (mgf) {N} and impregnating the aqueous solution, excess monomer aqueous solution was squeezed out with a roller. The impregnated material was heated and radical polymerization was performed on the substrate to obtain a comparative liquid-absorbent composite (2).
The wet shape retention of the comparative liquid-absorbent composite (2) was 6%. (Example 4) 66 mm * 162 mm absorbent composite (1)
Was provided with a leak-proof film at the bottom and further wound with rayon paper to obtain a sanitary napkin (1). The sanitary napkin (1) had a small thickness and a soft texture, and was gripped by hand with 10 ml of sheep blood absorbed, but immediately restored to its original shape. (Example 5) Instead of the absorbent composite (1), the absorbent composite (2)
Sanitary napkin (2) under the same conditions as in Example 4 except that
I got This sanitary napkin (2) had a small thickness and a soft texture, and was gripped by hand with 10 ml of sheep blood absorbed, but immediately restored to its original shape. (Example 6) Absorbent composite (3) instead of absorbent composite (1)
Sanitary napkin (2) under the same conditions as in Example 4 except that
I got The sanitary napkin (3) had a small thickness and a soft texture, and was absorbed by 10 ml of sheep blood, but was immediately restored to its original shape. (Comparative Example 2) A comparative sanitary napkin (1) was obtained under the same conditions as in Example 4, except that the comparative absorbent composite (2) was used instead of the absorbent composite (1). The feel of this comparative sanitary napkin (1) was hard and difficult to handle, and the one that absorbed 10 ml of sheep blood was grasped by hand, but was not restored to its original shape. (Production Example 2 of Comparative Liquid Absorbent Complex) 0.1 mol% of N, N'-methylenebisacrylamide (based on monomer) was added to a partially neutralized aqueous solution of sodium acrylate in which 99 mol% was neutralized with sodium hydroxide. 1.5% by weight of hydroxyethyl cellulose (based on monomer) and 1.0 g / mole of sodium persulfate (based on monomer) and 0.5 g / mole of 2,2′-azobis (N, N ′ dimethyleneisobutylamidine) dihydrochloride (To the monomer) was dissolved to prepare a 34% by weight aqueous monomer solution.

Next, 5 denier,
Made of polyester fiber having a fiber length of 30 mm, a basis weight of 50
g / m ² of a nonwoven fabric (thermal fusion treatment) was immersed and impregnated with the aqueous solution, and excess monomer aqueous solution was squeezed out with a roller. The impregnated material was heated and radical polymerization was performed on the substrate to obtain a comparative liquid-absorbent composite (3). Comparative absorbent composite (3)
Was 0%. (Example 7) Thickness 1 mm * width 10 mm * length 110 mm
Of the absorbent composite (1) was immersed in ion-exchanged water for 1 hour to cause water absorption and swelling. At this time, the thickness was 5.1 mm.
The liquid-absorbent composite (1) was placed on a horizontal table, and a weight was placed from above to apply a load of 0.91 kg / cm ² . One minute later, the weight is removed in the horizontal direction and the swollen absorbent composite (1)
Was measured and the thickness was 5.0 mm. The thickness remained almost unchanged and maintained the expanded form. (Comparative Example 3) thickness 1 mm * width 10 mm * length 110 mm
The liquid-absorbent composite (3) was immersed in ion-exchanged water for 1 hour to swell. The thickness at this time is 7. It was 0 mm. The comparative liquid-absorbent composite (3) was placed on a horizontal table, and a weight was placed from above to apply a load of 0.91 kg / cm ² . One minute later, the thickness of the comparative liquid-absorbent composite (3), which was swollen by removing the weight in the horizontal direction, was measured and found to be 3.5 m.
m. The thickness was reduced by 50% with respect to the thickness at the time of swelling, and the expanded form could not be maintained. (Example 8) The amount of liquid leakage when the liquid-absorbent composite (1) was used as a liquid leakage preventing material for an absorber was measured. No liquid leakage
g did not leak at all. (Comparative Example 4) The amount of liquid leakage was measured using only the absorber without disposing the liquid leakage preventing material. The amount of liquid leakage was 51 g, and the surrounding area was contaminated.

[0061]

The liquid-absorbent composite used in the body fluid-absorbing article of the present invention has excellent wet shape retention properties, and is easily restored to its original shape when deformed after liquid absorption. Therefore, the liquid absorption rate is high and the amount of return is small and the liquid leakage prevention property is excellent. Further, the absorbent composite used in the body fluid absorbing article of the present invention is compressed, and maintains a compressed state until the first liquid absorption occurs, and is thin, so that products such as disposable diapers, napkins, etc. In this case, a thin product can be obtained. In addition, the density of the liquid-absorbent composite obtained by compression increases, and "strain" appears in the texture, so that it is excellent in shape retention and prevents kinking.

Further, when a substrate having a high compression restoring elasticity such as a sponge is used, the restoring elastic force of the substrate and
Due to the liquid-absorbing swelling property of the liquid-absorbing polymer, the liquid-absorbing polymer exhibits extremely high volume expansion together with rapid liquid absorption.

Claims (7)

[Claims] 1. A body fluid absorbing article comprising at least partially disposed a compressed liquid absorbing composite comprising at least a liquid absorbing polymer and a substrate supporting the liquid absorbing polymer. A body fluid absorbing article characterized in that the liquid composite has a wet shape retention of 10% or more. 2. The body fluid absorbing article according to claim 1, wherein the compression elasticity ratio of the base material is 3 or more. 3. The article for absorbing body fluid according to claim 1, wherein the substrate is a polyurethane sponge substrate. 4. The base material has a softness of 2000 (mgf) {N}.
The body fluid absorbing article according to any one of claims 1 to 3, wherein: 5. The body fluid absorbing article according to claim 1, wherein the liquid-absorbing complex is obtained by polymerizing a water-soluble unsaturated monomer on a substrate. 6. The body fluid-absorbing article according to claim 1, wherein the liquid-absorbent composite is a product obtained by applying a water-soluble binder and compressing the composite. 7. The body fluid-absorbing article according to claim 1, wherein the liquid-absorbent composite is disposed around the absorbent core as a liquid leakage preventing material.