JP2003206324A - Water absorbing material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a water absorbing material without marked decline of characteristic absorption features to blood. <P>SOLUTION: The water absorbing material contains polyacidic amino acids and/or their salts and is composed of water absorbing resin particles prepared by the reaction of a polyacidic amino acid having at least one ethylenic unsaturated double bond in the molecule and an ethylenic unsaturated compound and has a molecular structure of fused primary particles with an average particle size of 100-1,000 μm and bulk density of 0.1-0.6 g/mL. <P>COPYRIGHT: (C)2003,JPO

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel and useful water-absorbing material.

[0002]

2. Description of the Related Art Conventionally, as a blood-absorbing article such as a panty liner or a sanitary napkin, a liquid-permeable surface material made of a nonwoven fabric or the like and a liquid impermeable material made of a polyethylene sheet or a polyethylene sheet-laminated nonwoven fabric are used. It has been known that an absorbent made of hydrophilic absorbent paper or cotton pulp that physically absorbs and retains blood is interposed between the leakage material. Among them, with regard to the material of the absorber, it has been proposed to improve the absorption capacity of blood by using a water-absorbing resin instead of absorbent paper or pulp, and to prevent leakage by retaining blood after absorption.

[0003] As a water absorbing resin of this kind,
Hydrolysates of starch-acrylonitrile graft copolymer, crosslinked carboxymethylcellulose, crosslinked polyacrylic acid (salt), acrylic acid (salt) -vinyl alcohol copolymer, crosslinked polyethylene oxide, and the like are known. However, since these conventional water-absorbent resins are developed to absorb urine instead of blood,
Adsorption of proteins, blood cell components, and tissue decomposed products in blood on the surface of the highly water-absorbent resin enhances adhesion between particles and promotes gel blocking, so that there is a problem that absorption characteristics are significantly reduced.

[0004] As one of the prescriptions for solving this problem and improving the absorbability of the water-absorbent resin to blood, a modification method for increasing the surface area of the water-absorbent resin is known. As one method for preparing such a water-absorbent resin aggregate having a large surface area, a water-soluble polymerizable monomer containing a phosphate ester surfactant in a hydrophobic organic solvent containing a phosphate ester surfactant is used. A method of performing suspension polymerization by supplying an aqueous solution is disclosed in JP-A-2001-2712,
Since this method was also developed mainly for improving the absorption characteristics of urine under pressure, it did not improve the blood absorption characteristics.

[0005] Under such circumstances, there has been a long-felt need to develop a water-absorbing material that does not significantly reduce absorption characteristics due to blood components.

[0006]

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a water-absorbing material having improved blood absorption characteristics.

[0007]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems, and as a result, they have a specific average particle diameter containing a polyacid amino acid and / or a salt thereof, and Found that the use of the water-absorbent resin particles having a structure in which the water-absorbent resin particles are fused makes it possible to increase the surface area of the water-absorbent resin particles, improve the wettability to blood, and improve the blood absorption characteristics. Thus, the present invention has been completed.

That is, the present invention provides a polyacid amino acid and / or
Or containing a salt thereof, having a structure in which primary particles are fused, having an average particle diameter of 100 to 1000 μm, and a bulk density of 0.1 to
An object of the present invention is to provide a water-absorbing material comprising water-absorbing resin particles of 0.6 g / ml.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Necessary items for carrying out the present invention will be specifically and in detail described below. The water-absorbent material of the present invention is a water-absorbent resin particle containing a polyacidic amino acid and / or a salt thereof, the particle having a structure in which primary particles are fused, an average particle diameter of 100 to 1,000 μm, and a bulk density of Is a water-absorbing material composed of water-absorbing resin particles having a non-spherical shape of 0.1 to 0.6 g / ml.

The polyacidic amino acids constituting the water-absorbent resin particles used in the present invention include polyaspartic acid and polyglutamic acid. These compounds may have a linear structure or may have a branched structure.

Further, in the basic skeleton of the polyacid amino acid,
It may contain an amide bond and an amino acid unit other than glutamic acid and aspartic acid. Glutamic acid, amino acid units other than aspartic acid, for example, glycine, alanine, valine, leucine, isoleucine, serine, threonine, asparagine, glutamine, lysine, ornithine, cysteine, cystine, methionine,
Aliphatic α-amino acids such as proline, hydroxyproline and arginine; aromatic α-amino acids such as tyrosine, phenylalanine, tryptophan and histidine;
-Substituted amino acid side chain functional group, aminocarboxylic acid such as β-alanine, γ-aminobutyric acid, glycyl-
Examples include amino acid units such as dipeptides (dimers) such as glycine and aspartyl-phenylalanine, and tripeptides (trimers) such as glutathione. These amino acids may be optically active (L-form, D-form) or racemic. Further, these amino acid units may be bonded to glutamic acid and aspartic acid and exist as a random copolymer, or may exist as a block copolymer.

The salts of polyacid amino acids used in the present invention include alkali metal salts, alkaline earth metal salts and ammonium salts of the above polyacid amino acids. Alkali metal salts include sodium salts, potassium salts, lithium salts, rubidium salts and the like, and alkaline earth metal salts include calcium salts, magnesium salts and the like.

The water absorbent resin particles used in the present invention are characterized by having a structure in which primary particles are fused. These water-absorbent resin particles are formed by the primary particles formed first being gradually fused during the manufacturing process. By having a structure in which the primary particles are fused, the surface area of the water-absorbent resin particles increases, and the wettability to blood can be increased.

The average particle size of the water-absorbent resin particles is required to be 100 to 1000 μm in order to increase the wettability of blood and make it difficult to form a cage. It is preferably from 500 to 500 μm. Here, the average particle diameter in the present invention is based on a numerical value obtained according to the method for measuring the average particle diameter in Examples described later.

The bulk density of the water-absorbent resin particles must be 0.1 to 0.6 g / ml in order to increase the wettability of blood, and is 0.2 to 0.5 g / ml. Preferably, there is. The bulk density refers to the apparent density of a material including bubbles, voids, and the like. The numerical value of the bulk density (ρ _k ) in the present invention is based on the value calculated by the equation (A) by setting the true density of the material to ρ, the porosity to ε, and the porosity specific to the material to p. Things.

Ρ _k = ρ (1−ε) (1−p) (A) The value of the porosity ε is a numerical value that can be changed depending on how the substance is filled into the material.

In order to obtain the water-absorbent resin particles used in the present invention, there is no particular limitation, but for example, a polyacid amino acid (A-1) having at least one ethylenically unsaturated double bond in the molecule. With the ethylenically unsaturated compound (B). When such a reaction is performed in the presence of a phosphate-based surfactant represented by the following general formula (1), the primary particles are fused, the surface area of the particles is increased, and the wettability of blood is increased. It is preferable in that it can be used.

Embedded image [Wherein, R¹Is an alkyl group having 8 to 30 carbon atoms or
Represents an alkylaryl group, and n represents an integer of 1 to 30
Then R²Is a hydroxyl group or R¹O- (CH₂CH₂O) _n−
(R¹And n are the same as those described above). ]

The water-absorbent resin particles used in the present invention are:
In the presence of the phosphate ester surfactant represented by the above general formula (1) and the polyacidic amino acid (A-2) having no ethylenically unsaturated double bond in the molecule, the ethylenically unsaturated compound The method of reacting (B) is also a preferable method because the same effect as described above can be obtained. Although any of these methods may be used, a comparison of the repetitive blood absorbency when blood is added again to the water-absorbent resin that has once absorbed blood shows that the polyacid amino acid having at least one ethylenically unsaturated double bond (A- It is preferable to use the method of reacting 1) with the ethylenically unsaturated compound (B), since the resulting water-absorbent resin can increase the repeated blood absorbency.

The phosphate ester surfactant used in the present invention has a structure represented by the above general formula (1).
In the above formula, R ¹ represents an alkyl group or an alkylaryl group having 8 to 30 carbon atoms, but from the viewpoint of industrial availability, an alkyl group or a monoalkylphenyl group having 8 to 23 carbon atoms. It is preferable that Preferred examples of R ¹ include a nonylphenyl group, an octylphenyl group, a tridecyl group, a lauryl group, a 2-ethylhexyl group, an octadecyl group, and a dodecylphenyl group.

In the above formula, n represents an integer of 1 to 30,
It is preferably 2 to 15. Also R²Is a hydroxyl group or R
¹O- (CH₂CH₂O)_n− (R¹And n are the same as above.
, But R¹O- (CH₂CH
₂O)_n-Two R ¹ O- (CH_Two CH_Two 
O)_n-Are preferably the same.

The commercial product of the phosphate ester surfactant is usually a mixture of a phosphate monoester and a phosphate diester.

The polyacid amino acid (A) having at least one ethylenically unsaturated bond in the molecule used in the present invention
Examples of -1) include, but are not particularly limited to, a polysuccinimide hydrolyzate (a) having a maleimide terminal group as a terminal group, and a polyacid amino acid;
Compounds (b) obtained by reacting a compound having a functional group having reactivity with an ethylenically unsaturated bond and a polyacidic amino acid in the molecule are included. Such a polysuccinimide having a maleimide terminal group can be obtained, for example, by reacting maleic anhydride, fumaric acid, malic acid, or the like with ammonia and passing through maleimide or maleamic acid.

The hydrolyzate (a) of a polysuccinimide having a maleimide terminal group can be obtained by subjecting the polysuccinimide obtained above to a hydrolysis reaction, usually by adding an aqueous alkali solution. The reaction temperature at this time is preferably in the range of 0 to 100 ° C, more preferably 20 to 95 ° C.

Examples of the alkali compound used in the alkaline aqueous solution include an alkali metal compound and / or an alkaline earth metal compound. As the alkali metal compound or the alkaline earth metal compound, among the above, hydroxides or carbonates are typical examples. Specifically, LiOH, NaOH, KOH, Mg (OH)
_{2, Ca (OH) 2,} Li 2 CO 3, Na 2 CO 3, K 2
CO ₃ , MgCO _3, CaCO _{3 and the} like can be mentioned. Generally, sodium hydroxide or potassium hydroxide is used, and it is preferable to use a 0.1 to 40% by weight aqueous solution of these compounds. The amount of the alkali compound used is
It is preferable to use 0.4 to 1.0 mol per one imide ring group.

The hydrolyzate of polysuccinimide having a maleimide terminal group (a) may be neutralized with a protonic acid such as hydrochloric acid, sulfuric acid or phosphoric acid for the purpose of adjusting pH.

The polyacid amino acid used in the compound (b) obtained by reacting a polyacid amino acid with a compound having an ethylenically unsaturated bond and a functional group reactive with the polyacid amino acid in the molecule includes: The above-mentioned polyacidic amino acids can be used.

The compound having a functional group reactive with an ethylenically unsaturated bond and a polyacidic amino acid in the molecule is not particularly limited, but in order to achieve the object of the present invention, for example, the following general formula: The compound represented by (2) is preferable.

[0027]

Embedded image Wherein R ₁ represents at least one group selected from the group consisting of an amino group, an epoxy group, a carboxyl group, a carbodiimide group, an oxazoline group, an imino group and an isocyanate group; 1 atom
10 represents an alkylene group, and R ₂ represents hydrogen or an alkyl group having 1 to 4 carbon atoms. )

Specific examples of the compound represented by the general formula (2) include glycidyl acrylate, glycidyl methacrylate, acrylic acid, methacrylic acid,
-Methacryloyloxyethyl isocyanate, 2-isocyanatomethyl acrylate and the like.

The polyacid amino acid (A-2) having no ethylenically unsaturated double bond used in the present invention includes the above-mentioned polyacid amino acids polyaspartic acid and polyglutamic acid.

As the ethylenically unsaturated compound (B) used in the present invention, any compound having an ethylenically unsaturated double bond in the molecule and having water solubility or water miscibility can be used. Can also be used. Specific examples of such compounds include, for example, ionic monomers such as (meth) acrylic acid and / or its alkali metal salt, ammonium salt, 2- (meth) acrylamido-2-methylsulfonic acid and / or its alkali metal salt; (Meth) acrylamide,
Non-ionic monomers such as N, N-dimethylacrylamide, 2-hydroxyethyl (meth) acrylate, N-methylol (meth) acrylamide; and non-amino-containing monomers such as diethylaminoethyl (meth) acrylate and dimethylaminopropyl (meth) acrylate Examples thereof include saturated monomers and quaternized products thereof. One of these or a mixture of two or more thereof can be used.

Among these, (meth) acrylic acid and / or
Alternatively, alkali metal salts, alkaline earth metal salts, ammonium salts, and (meth) acrylamide thereof are preferable. Examples of the alkali metal salt include sodium salt, potassium salt, lithium salt, rubidium salt and the like, and examples of the alkaline earth metal salt include calcium salt and magnesium salt. Here, the term “(meth) acryl” means “acryl” and “methacryl”.

The ethylenically unsaturated compound (B) is preferably
By using a polyfunctional ethylenically unsaturated compound having two or more ethylenically unsaturated groups or a compound having two or more reactive groups as a cross-linking agent, water absorbing properties can be exhibited.

As the polyfunctional ethylenically unsaturated compound, basically any compound can be used as long as it is an ethylenically unsaturated compound having two or more ethylenically unsaturated groups. Specifically, for example, N, N'-methylenebis (meth) acrylamide, (poly) ethylene glycol di (meth) acrylate, (poly) propylene glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, trimethylol Propane di (meth) acrylate, glycerin tri (meth) acrylate, glycerin acrylate methacrylate, ethylene oxide modified trimethylolpropane tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol hexa (meth) acrylate, and the like. be able to.

Compounds having two or more reactive groups include, for example, ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, glycerin, polyglycerin, propylene glycol, 1,4-butanediol, 1,5 -Pentanediol, 1,6-hexanediol, neopentyl alcohol, diethanolamine, tridiethanolamine,
Polyhydric alcohols such as polypropylene glycol, polyvinyl alcohol and pentaerythritol, sorbit,
Sugar alcohols such as sorbitan, sugars such as glucose, mannitol, mannitan, sucrose and glucose; polyglycidyl ethers such as ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether and glycerin triglycidyl ether; epichlorohydrin, α- Haloepoxy compounds such as methyl chlorohydrin; polyaldehydes such as glutaraldehyde and glyoxal; polyamines such as ethylenediamine; calcium hydroxide, calcium chloride, calcium carbonate, calcium oxide, magnesium borax, magnesium oxide,
Polyvalents such as hydroxides, halides, carbonates, oxides, borates such as borax, and aluminum isopropylate of metals of Groups 2A, 3B and 8 of the periodic table such as aluminum chloride, zinc chloride and nickel chloride. Metal compounds and the like.

One or two or more of these polyfunctional ethylenically unsaturated compounds having two or more ethylenically unsaturated groups or compounds having two or more reactive groups are
It can be used in consideration of reactivity.

Further, the method for producing the water-absorbent resin particles used in the present invention will be specifically described. That is, the phosphoric acid ester-based surfactant is contained in an inert solvent containing the phosphoric acid ester-based surfactant represented by the general formula (1), and at least one ethylenically unsaturated double molecule is contained in the molecule. A polyacid amino acid having a bond (A-1) or a polyacid amino acid having no ethylenically unsaturated double bond (A-
2) An aqueous solution containing the ethylenically unsaturated compound (B) and a cross-linking agent [hereinafter referred to as an aqueous solution of the ethylenically unsaturated compound (B)] and a radical initiator are supplied to form a water-in-oil reverse phase suspension. By subjecting the polymer particles obtained by polymerization to a surface cross-linking treatment, water-absorbent resin particles can be produced. In order to obtain the water-absorbent resin particles of the present invention, the above method is preferable.

The inert solvent used in the present invention means a hydrophobic solvent which is hardly soluble in water, and any solvent can be used as long as it is inert in the polymerization reaction for producing the resin particles of the present invention. Is not particularly limited. Such inert solvents include, for example, aliphatic hydrocarbons such as n-pentane, n-hexane, n-heptane and n-octane; alicyclic hydrocarbons such as cyclohexane and methylcyclohexane; aromatics such as benzene, toluene and xylene. Hydrocarbons and the like. Of these, aliphatic hydrocarbons such as n-hexane, n-heptane, and cyclohexane, or cyclic hydrocarbons are preferred because a water-absorbent resin with no stickiness is obtained.

The amount of the phosphate surfactant used in the inert solvent is usually preferably 0.01 to 5% by weight. When the amount is within this range, a desired dispersing effect can be obtained without lowering the blood absorbing properties of the water absorbent resin particles of the present invention.

The amount of the inert solvent used is based on the aqueous solution of the ethylenically unsaturated compound (B) used in the reaction.
A range of 0.5 to 10 times by weight is preferable.

The amount of the phosphate-based surfactant used in the aqueous solution of the ethylenically unsaturated compound (B) depends on the concentration (X) of the phosphate-based surfactant in the inert solvent and the amount of the ethylenically unsaturated compound. The ratio (X / Y) to the concentration (Y) of the phosphate ester surfactant in the aqueous solution of the compound (B) is

It is preferable that the compound is added so that 0 <X / Y ≦ 10. When the amount of the phosphate ester surfactant in the aqueous solution of the ethylenically unsaturated compound (B) is within the above range, the average particle diameter of the resulting water-absorbent resin particles can be controlled to 100 to 1000 μm, and blood absorption The characteristics can be improved.

Examples of the radical polymerization initiator include inorganic peroxides (hydrogen peroxide, ammonium persulfate, potassium persulfate, sodium persulfate, etc.) and organic peroxides (benzoyl peroxide, di-t-butyl peroxide). , Cumene hydroxyperoxide, succinic peroxide, di (2-ethoxyethyl) peroxydicarbonate, etc., azo compounds (azobisisobutylnitrile, azobiscyanovaleric acid, 2,2′-azobis (2-aminopropane) hydro And redox catalysts (combinations of reducing agents such as alkali metal sulfites or bisulfites, ammonium sulfite, ammonium bisulfite, and ascorbic acid) and oxidizing agents such as alkali metal persulfates, ammonium persulfate, and peroxides. Consisting of
Is mentioned.

The phosphate ester surfactant in the inert solvent and the phosphate ester surfactant in the aqueous solution of the ethylenically unsaturated compound (B) are different even if they are the same. Is also good.

In the water-in-oil type reverse phase suspension polymerization used in the present invention, an ethylenically unsaturated compound (B) containing a phosphate ester surfactant is added to an inert solvent containing a phosphate ester surfactant. The above method is carried out by supplying the aqueous solution of (1), dispersing the aqueous solution in oil in the form of droplets, and polymerizing.

Even if the above polymerization reaction is started after supplying the entire aqueous solution of the ethylenically unsaturated compound (B) into the inert solvent, the aqueous solution of the ethylenically unsaturated compound (B) may be divided during the polymerization. Although they may be supplied sequentially, the latter method is preferred. In the former method of starting the polymerization reaction after supplying the entire amount of the aqueous solution of the ethylenically unsaturated compound (B), the operation range in which desired water-absorbent resin particles can be produced is narrowed,
In addition, it becomes difficult to remove heat generated by polymerization.

On the other hand, in the latter method, a part of an aqueous solution of the ethylenically unsaturated compound (B), usually 1 to 25%, is first fed into an inert solvent to start polymerization, and the polymerization of this compound is started. After a certain degree of progress, polymerization is carried out while sequentially supplying the remaining aqueous solution of the ethylenically unsaturated compound (B).

As a method other than the above method, the polymerization is carried out simultaneously while sequentially supplying the aqueous solution of the ethylenically unsaturated compound (B) from the beginning to the inert solvent previously set under the polymerization conditions. Is also good.

In carrying out these methods, a mixture of the aqueous solution of the ethylenically unsaturated compound (B) and a part of the inert solvent is used as the aqueous solution of the ethylenically unsaturated compound (B), May be supplied in an inert solvent. The supply of the aqueous solution of the ethylenically unsaturated compound (B) is usually performed over a period of 20% or more, preferably 40% or more of the total polymerization time.

The supply of the aqueous solution of the ethylenically unsaturated compound (B) is usually carried out at a constant rate, but if desired, the supply rate may be changed on the way, and the supply may be temporarily interrupted on the way. You can also. For example, polymerization is started by continuously supplying an aqueous solution of the ethylenically unsaturated compound (B) into a hydrophobic organic solvent under polymerization conditions, and 1 to 25% of the aqueous solution of the ethylenically unsaturated compound (B) is added. At the time of the supply, the supply of the aqueous solution of the ethylenically unsaturated compound (B) is stopped for 3 to 60 minutes, preferably 5 to 30 minutes to allow only the polymerization to proceed, and then the ethylenically unsaturated compound ( An aqueous solution of B) can be supplied. This method is one of the preferred embodiments for producing the water-absorbent resin particles of the present invention.

The polymerization temperature depends on the polymerization initiator, but is usually from 40 to 150 ° C. If the temperature is too high, self-crosslinking proceeds, and the water absorption capacity of the generated resin particles decreases. On the other hand, when the temperature is too low, not only long time is required for polymerization, but also sudden polymerization may be caused to form lumps. A suitable polymerization temperature is 60 to 90 ° C., and it is particularly preferable to carry out the polymerization under the reflux condition of an inert solvent.

A polyacid amino acid (A-1) having at least one ethylenically unsaturated double bond in the molecule or a polyacid amino acid (A-2) having no ethylenically unsaturated double bond in the molecule The method of adding the compound to the inert solvent is not particularly limited, but may be an aqueous solution or a molecule of a polyacid amino acid (A-1) having at least one ethylenically unsaturated double bond in a previously hydrolyzed molecule. Polyacidic amino acid having no ethylenically unsaturated double bond (A
A method in which the aqueous solution of -2) is preliminarily mixed with an aqueous solution of the ethylenically unsaturated compound (B) and then added;
After adding the aqueous solution of the ethylenically unsaturated compound (B),
The method of adding is mentioned.

Any of these methods may be used, but the method is preferable in that the stability of the system can be maintained more. After adding an aqueous solution of the ethylenically unsaturated compound (B), a polyacidic amino acid (A-1) having at least one ethylenically unsaturated double bond in the molecule and an ethylenically unsaturated double bond in the molecule are added. Polyacid amino acids without (A-2)
When adding an aqueous solution of the above, the aqueous solution may be added as it is, or an inert solvent obtained by dissolving a surfactant in an aqueous solution of the polyacidic amino acid (A-1) or the polyacidic amino acid (A-2) may be used. After addition, the mixture is stirred and dispersed, and then added. The latter addition method is more preferable because the resin particles do not agglomerate and the polymerization stability is improved. At this time, the surfactant to be dissolved in the aqueous solution of the polyacidic amino acid (A-1) or the polyacidic amino acid (A-2) is not particularly limited, and a phosphate ester-based interface used in the above-described reverse phase suspension polymerization method. One or more activators can be used in combination.

Among the stirring conditions in the reversed-phase suspension polymerization, the absolute value of the stirring rotation speed cannot be uniquely shown because the absolute value varies depending on the type of the stirring blade used and the scale of the polymerization reaction tank. Since the stirring speed affects the average particle size of the polymer particles, and in order to achieve the object of the present invention, the average particle size is preferably in the range of 100 μm to 1000 μm.
The rotation speed is preferably in the range of rpm.
More preferably, it is in the range of 0 to 1000 rpm.
By appropriately selecting the type of the stirring blade and the stirring power at the stirring rotation speed in this range, it is possible to obtain water-absorbent resin particles having a large wetted area to blood and having a structure in which primary particles are fused.

By the above-mentioned reversed-phase suspension polymerization method, a hydrated gel,
A slurry mixture of excess surfactant and inert solvent is produced. The slurry-like mixture can be subjected to a known method, for example, direct dehydration or azeotropic dehydration with an inert solvent, followed by drying, sieving, etc., to obtain gel-like water-absorbent resin particles.

The water-absorbent resin particles used in the present invention can further increase the osmotic pressure on blood by subjecting the water-absorbent resin particles obtained above to a cross-linking reaction near the surface of the particles using a surface cross-linking agent. be able to. The surface cross-linking of the particles makes it possible to further enhance the blood absorption characteristics.

Examples of such a surface cross-linking agent include compounds having two or more functional groups capable of reacting with a functional group near the surface of the water-absorbent resin particles. In addition, when used in blood-absorbing articles and the like, they remain on the surface of the particles, and are therefore preferably highly safe for the human body.

Examples of such compounds include compounds having a reactive group capable of reacting with two or more carboxyl groups (carboxylate groups) such as polyamine and polyglycidyl ether, and γ-glycidoxypropyltrimethoxy. Silane coupling agents such as silane, γ-glycidoxypropylmethyldiethoxysilane, N-β- (aminoethyl) -γ-aminopropyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane, and dibutyltin dilaurate as a silanol condensation catalyst And ethylenically unsaturated compounds having a reactive group such as glycidyl methacrylate such as dibutyltin diacetate and dibutyltin dioctoate. One or more of these can be used.

The surface cross-linking of the water-absorbent resin particles is carried out by directly dewatering the swollen bead-like particles after reverse phase suspension polymerization by an appropriate method such as azeotropic dehydration or heating.
It can be carried out by mixing a powdery resin dried to a predetermined moisture content with a surface crosslinking agent. At this time,
In order to uniformly mix the resin and the surface crosslinking agent, it is preferable to use water and a hydrophilic solvent. The water and the hydrophilic solvent may be used by mixing 50 parts by weight or less of water and 60 parts by weight or less of the hydrophilic solvent with respect to 100 parts by weight of the resin.

Examples of the hydrophilic solvent include lower alcohols such as methanol, ethanol, n-propanol, isopropanol, n-butanol and isobutanol, ketones such as acetone and methyl ethyl ketone, dioxane, tetrahydrofuran,
And ethers such as diethyl ether, N, N-
Examples include amides such as dimethylformamide and N, N-diethylformamide, and sulfoxides such as dimethylsulfoxide.

The method of mixing the resin and the surface crosslinking agent is not particularly limited, and for example, a known mixing device can be used. Known mixing devices include, for example, a cylindrical mixer, a double-walled conical mixer, a high-speed stirring mixer, a V-shaped mixer,
Ribbon type mixer, screw type mixer, fluid type furnace rotary desk type mixer, air flow type mixer, double arm type kneader,
Examples of the mixing device include an internal mixer, a pulverizing kneader, a rotary mixer, and a screw extruder. For mixing with these mixing devices, it is preferable to add the surface cross-linking agent while stirring the resin, and it is more preferable to add the surface cross-linking agent while spraying.

The heating time at the time of surface cross-linking is appropriately selected depending on the heating temperature. In order to obtain water-absorbing resin particles having high water-absorbing performance without causing thermal deterioration, a temperature of 60 ° C. to 300 ° C. It is preferably from 5 minutes to 100 hours or less.

The heating device is not particularly limited,
Usually, a dryer or a heating furnace can be used. Specifically, for example, a groove-type mixing dryer, a rotary dryer, a disk dryer, a fluidized-bed dryer, a gas-flow dryer, an infrared dryer, a reduced-pressure dryer and the like can be mentioned.

The water-absorbing material of the present invention is composed of specific water-absorbing resin particles obtained by performing the above-mentioned operations, and exhibits particularly excellent blood absorption characteristics. The blood absorption amount is not particularly limited, but is preferably 6 g / g or more.

By using the water absorbing material of the present invention,
A blood absorbing article can be made. The above-mentioned blood-absorbing article comprises the water-absorbing material of the present invention, and usually has an absorber containing an absorbent material and a fiber material disposed between a liquid-permeable sheet and a liquid-impermeable sheet. It has a structure in which the absorber is held inside.

As a specific method of manufacturing the blood absorbent article, the absorbent is sandwiched between a liquid permeable sheet and a liquid impermeable sheet, and the liquid permeable sheet and the liquid impermeable sheet are sandwiched between the liquid permeable sheet and the liquid impermeable sheet. A method in which the outer edge of the sheet is joined with an adhesive such as a hot-melt adhesive or an adhesive means such as heat sealing may be used.

The method for producing the absorbent containing the water-absorbing material and the fiber material is not particularly limited, but 1) a method in which the fiber material is formed into a sheet and the sheet is wrapped with the water-absorbing material, 2) a multilayer fiber. A method in which a water-absorbent material is sprayed on a sheet to form the multilayer sheet, a method in which a fiber material and a water-absorbent material are mixed and formed into a sheet, and the like are exemplified.

The blood-absorbing article is required to have blood-absorbing properties such as sanitary napkins, tampons, medical blood-absorbing sheets, drip absorbents, wound protection materials, wound healing materials, and wastewater treatment agents for surgery. Articles. Also,
Water containing protein as well as blood, such as milk, breast milk, vaginal discharge, etc., exhibit excellent absorption properties, as well as urine, seawater, cement water, soil water, and fertilizer similar to conventional water-absorbing materials Since it has excellent absorption properties for water, rainwater, drainage, and the like, its application field is wide.

[0067]

The present invention will be described more specifically with reference to examples and comparative examples. In the following, all percentages are by weight unless otherwise specified. still,
The properties of the material were measured by the methods outlined below.
Table 1 summarizes the charged compositions of Examples 1 to 3 and Comparative Examples 1 and 2.

[Measurement Method of Blood Suction Amount] A 15-layered toilet paper (55 mm × 75 mm) immersed in 20 ml of horse delipidated blood (obtained from Japan Biomaterials Center Co., Ltd.) in a petri dish with an inner diameter of 95 mm is described later. About 1 g of the water-absorbing resin particles obtained in the example was added, and after absorbing the liquid for 5 minutes, a swelling gel of the resin was collected and its weight was measured. The weight of the swollen gel after the liquid absorption was divided by the weight of the resin particles before the liquid absorption to calculate the blood suction amount (g / g).

[Measurement Method of Average Particle Diameter] The water-absorbent resin particles obtained in the following Examples were mixed with a mesh of 16 mesh (100 mesh).
0 μm), 30 mesh (500 μm), 100 mesh (150 μm), 140 mesh (106 μm), 2
35 mesh (63 μm) sieve (JIS-Z880
1) Combined in the order of the tray, and about 20 g of the resin particles were put into the uppermost sieve and shaken sufficiently. The weight of the resin particles remaining on each sieve was weighed, and the total weight was taken as 100%, the particle size distribution was determined from the weight fraction, and the 50% particle size on a weight basis was taken as the average particle size.

[Method of measuring bulk density] JIS K-67
21. The measurement was performed three times, and the average value was obtained.

Reference Example 1 Production Example of Polysuccinimide Maleic anhydride 96 was placed in a 1-L four-necked flask equipped with a stirrer, thermometer, reflux device, and nitrogen gas blowing device.
g and 50 g of ion-exchanged water. Next, the mixture was heated to 55 ° C. to dissolve maleic anhydride, and then cooled once to obtain a maleic anhydride slurry. Heat the system again, 55 ℃
Then, 60.8 g of 28% aqueous ammonia was added. Thereafter, the temperature in the system was raised to 80 ° C. After reacting for 3 hours, the obtained aqueous solution was dried to obtain a reaction intermediate. 100 g of the reaction intermediate and 10 g of 85% phosphoric acid were charged into a 2 L eggplant flask, and reacted at 200 ° C. under reduced pressure for 4 hours in an oil bath using an evaporator. The obtained product was washed several times with water and methanol. As a result of measuring the obtained polysuccinimide by GPC, the weight average molecular weight was 3,000.

Example 1 75 g of an aqueous solution in which 20.6 g of sodium hydroxide was dissolved was added to a 500 ml four-necked flask equipped with a stirring device, a thermometer, a reflux device, and a nitrogen gas blowing device. An aqueous solution of polysuccinimide was obtained by adding 50 g of the polysuccinimide powder obtained in Example 1. Next, after the temperature was raised to 90 ° C., 5.0 g of glycidyl methacrylate was added, and the mixture was reacted for 1 hour to obtain an aqueous solution containing a methacryloyl group-introduced polyaspartic acid hydrolyzate.

Acrylic acid 3 was placed in a 500 ml Erlenmeyer flask.
0 g, and 8.74 g of lithium hydroxide monohydrate dissolved therein while cooling from the outside.
5 g was added dropwise to neutralize 50 mol% of the acrylic acid. 1.12 g of Plysurf A210G (polyoxyethylene octyl phenyl ether phosphate, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) was added to this solution and dissolved. Further, 23.4 mg of N, N'-methylenebisacrylamide and 0.04% of ammonium persulfate were added to this solution.
5 g was added and dissolved.

Separately, 164 g of cyclohexane was added to a 500 ml four-necked flask equipped with a stirrer, a thermometer, a reflux device, and a nitrogen gas blowing device, and 0.82 g of Plysurf A210G was added thereto.
It was dispersed while stirring at rpm. Next, after the flask was replaced with nitrogen, the temperature was raised to 75 ° C., and the acrylic acid aqueous solution prepared above was added dropwise over 60 minutes. After the dropwise addition, 7.8 g of the previously obtained methacryloyl group-introduced polyaspartic acid aqueous solution was added thereto all at once. Next, after maintaining at 70 to 75 ° C. for 3 hours, dehydration was performed until the water content of the resin formed by azeotropic distillation with cyclohexane became 10%. still,
Stirring was performed at a constant rotation speed of 500 rpm. After the reaction, the cyclohexane phase was separated by decantation,
Subsequently, water was removed from the obtained water-containing resin particles by drying under reduced pressure to obtain a polymer powder.

In a 500 ml flask, 30 g of the obtained polymer particles were weighed, and a mixed solution comprising 1.2 g of acetone, 2.1 g of ion-exchanged water, 0.09 g of glycidyl methacrylate, and 0.09 g of ammonium persulfate was added thereto. Silica (Nippon Aerosil Co., Ltd., 200CF)
0.3 g was evenly sprayed. Aqueous resin particles at 108 ° C
The surface of the resin particles was crosslinked by drying under reduced pressure for a time. Microscopic observation of the obtained water-absorbent resin particles revealed that the particles had a structure in which primary particles were fused as shown in FIG. Table 1 shows the average particle diameter measured according to the above average particle diameter measurement method and the bulk density measured according to the above bulk density measurement method.

The results of evaluating the properties of the water-absorbent material of the present invention comprising the above water-absorbent resin particles are shown in Table 1-1. Example 1
As shown in Table 1, the water-absorbing material obtained in the above is excellent in blood absorbing power and has an affinity for blood.

Example 2 Water-absorbent resin particles were obtained in the same manner as in Example 1, except that the amount of N, N'-methylenebisacrylamide was changed to 93.6 mg. Microscopic observation of the obtained water-absorbent resin particles revealed that the particles had a structure in which primary particles were fused. Table 1 shows the average particle diameter measured according to the above average particle diameter measurement method and the bulk density measured according to the above bulk density measurement method. Table 1 shows the property evaluation results of the water-absorbing material of the present invention. As shown in Table 1, the water-absorbing material obtained in Example 2 has an excellent blood absorbing ability and has an affinity for blood.

Example 3 1.68 g of Plysurf A210G was added to a neutralized aqueous solution of acrylic acid in lithium hydroxide, and Plysurf A210G was added to cyclohexane.
Water absorbent resin particles were obtained in the same manner as in Example 1 except that 0.41 g was added. Microscopic observation of the obtained water-absorbent resin particles revealed that the particles had a structure in which primary particles were fused. Table 1 shows the average particle diameter measured according to the above average particle diameter measurement method and the bulk density measured according to the above bulk density measurement method. Table 1 shows the property evaluation results of the water-absorbing material of the present invention. As shown in Table 1, the water-absorbing material obtained in Example 3 has excellent blood absorbing ability and has an affinity for blood.

Example 4 75 g of an aqueous solution in which 20.6 g of sodium hydroxide was dissolved was added to a 500 ml four-necked flask equipped with a stirring device, a thermometer, a reflux device, and a nitrogen gas blowing device. An aqueous solution of polyaspartic acid was obtained by adding 50 g of the polysuccinimide powder obtained in Example 1. Water-absorbent resin particles were obtained in the same manner as in Example 1, except that 7.8 g of the aqueous polyaspartic acid solution obtained by this operation was added all at once. Microscopic observation of the obtained water-absorbent resin particles revealed that the particles had a structure in which primary particles were fused. Table 1 shows the average particle diameter measured according to the above average particle diameter measurement method and the bulk density measured according to the above bulk density measurement method. As shown in Table 1, the water-absorbing material obtained in Example 4 has excellent blood absorbing ability and has an affinity for blood. << Comparative Example 1 >> 30 g of acrylic acid was added to a 500 ml Erlenmeyer flask, and 81.5 g of an aqueous solution of lithium hydroxide in which 8.74 g of lithium hydroxide monohydrate was dissolved was added dropwise while cooling from the outside. Mol%
Was neutralized. 23.4 mg of N, N'-methylenebisacrylamide was added to this solution, and 0.05 g of ammonium persulfate was further added and dissolved.

Separately, 164 g of cyclohexane was added to a 500 ml four-necked flask equipped with a stirring device, a thermometer, a reflux device, and a nitrogen gas blowing device, and 0.82 g of Plysurf A210G was added, followed by 500 rpm.
While stirring at a rotation speed of. Next, after the flask was replaced with nitrogen, the temperature was raised to 75 ° C., and the acrylic acid aqueous solution prepared above was added dropwise over 60 minutes. After the dropwise addition, the previously obtained dispersion solution of the aqueous solution of the hydrolyzate of polysuccinimide into which the methacryloyl group was introduced was added at once.

Then, after maintaining at 70 to 75 ° C. for 3 hours,
Dehydration was performed until the water content of the resin particles generated by azeotropic distillation with cyclohexane became 10%. In addition, stirring is 50
The test was performed at a constant rotation speed of 0 rpm. After completion of the reaction, the cyclohexane phase was separated by decantation, and then water was removed from the water-containing resin particles by drying under reduced pressure to obtain a polymer powder.

30 g of the obtained polymer particles were weighed in a 500 ml flask and subjected to a surface crosslinking treatment in the same manner as in Example 1. Microscopic observation of the obtained water-absorbent resin particles showed that the primary particles had a fused structure,
As shown in Table 1, excellent blood absorption ability could not be obtained. Table 1 shows the average particle diameter measured according to the above average particle diameter measurement method and the bulk density measured according to the above bulk density measurement method.

Comparative Example 2 To a 500 ml four-necked flask equipped with a stirrer, a thermometer, a reflux device, and a nitrogen gas blowing device, 164 g of cyclohexane was added, and DK ester F-90 (surfactant HLB = 0.75 g of sucrose ester of No. 9 (Daiichi Kogyo Seiyaku Co., Ltd.) was added, and the mixture was heated to 50 ° C. with stirring to dissolve. Thereafter, the contents of the flask were cooled to 30 ° C. On the other hand, 50
30 g of acrylic acid was added to a 0 ml Erlenmeyer flask, and 86.5 g of an aqueous sodium hydroxide solution in which 8.3 g of sodium hydroxide was dissolved was added dropwise while cooling from the outside to neutralize 50 mol% of acrylic acid. 23.4 mg of N, N'-methylenebisacrylamide was added to this solution, and 0.05 g of ammonium persulfate was further added and dissolved.

Next, the aqueous solution of the acrylate containing the polymerization initiator and the crosslinking agent obtained as described above was added to the contents of the above-mentioned cylindrical round bottom flask, and cyclohexane containing a surfactant was added. It was dispersed in a solution and the inside of the system was sufficiently replaced with nitrogen. Thereafter, the temperature was raised by heating to start the polymerization reaction. Thereafter, the temperature was maintained at 60 to 65 ° C. for 3 hours. The stirring was performed at 300 rpm. After completion of the reaction, the cyclohexane phase was separated by decantation, and then water was removed from the wet polymer by drying under reduced pressure to obtain a polymer powder.

In a 500 ml flask, 30 g of the obtained polymer particles were weighed and subjected to a surface crosslinking treatment in the same manner as in Example 1. Microscopic observation of the obtained water-absorbent resin particles did not show a structure in which the primary particles were fused. Table 1 shows the average particle diameter measured according to the above average particle diameter measurement method and the bulk density measured according to the above bulk density measurement method. Table 1 shows the property evaluation results of the obtained water-absorbing material.

[0086]

[Table 1]

The water-absorbing material of the present invention has excellent blood absorption properties and also excellent absorption of protein-containing water and the like. Therefore, sanitary napkins, tampons, medical blood-absorbing sheets, drip absorbents It can be applied to various uses requiring blood, blood absorption characteristics, and the like.

[Brief description of the drawings]

FIG. 1 is an electron micrograph of water-absorbent resin particles obtained in Example 1.

────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] February 14, 2002 (2002.2.1
4)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claims

[Correction method] Change

[Correction contents]

[Claims]

Embedded image [Wherein, R ¹ is an alkyl group having 8 to 30 carbon atoms,
Or an alkylaryl group, n represents an integer of 1 to 30, R ² represents a hydroxyl group or R ¹ O— (CH ₂ CH ₂ O) _n
-(R ¹ and n are the same as described above). ]

Embedded image [Wherein, R ¹ is an alkyl group having 8 to 30 carbon atoms,
Or an alkylaryl group, n represents an integer of 1 to 30, R ² represents a hydroxyl group or R ¹ O— (CH ₂ CH ₂ O) _n
-(R ¹ and n are the same as described above). ]

Embedded image [Wherein, R ¹ is an alkyl group having 8 to 30 carbon atoms,
Or an alkylaryl group, n represents an integer of 1 to 30, R ² represents a hydroxyl group or R ¹ O— (CH ₂ CH ₂ O) _n
-(R ¹ and n are the same as described above). ]

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0017

[Correction method] Change

[Correction contents]

The water-absorbent resin particles used in the present invention are:
In the presence of the phosphate ester surfactant represented by the above general formula (1) and the polyacidic amino acid (A-2) having no ethylenically unsaturated double bond in the molecule, the ethylenically unsaturated compound The method of polymerizing (B) is also a preferable method because the same effect as described above can be obtained. Either of these methods may be used. However, when the repetitive blood absorbability when blood is added again to the water-absorbent resin that has once absorbed blood is compared, a polyacid amino acid (A) having at least one ethylenically unsaturated double bond in the molecule is used. -1) and the method of reacting the ethylenically unsaturated compound (B),
This is preferable in that the obtained water-absorbent resin can increase the repeated blood-absorbing property.

[Procedure amendment 3]

[Document name to be amended] Statement

[Correction target item name] 008

[Correction method] Change

[Correction contents]

[0086]

[Table 1]

The water-absorbing material of the present invention has excellent blood absorption properties and also excellent absorption of protein-containing water and the like. Therefore, sanitary napkins, tampons, medical blood-absorbing sheets, drip absorbents It can be applied to various uses requiring blood, blood absorption characteristics, and the like.

[Brief description of the drawings]

FIG. 1 is an electron micrograph of water-absorbent resin particles obtained in Example 1.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI theme coat ゛ (reference) C08F 290/06 F term (reference) 4C003 AA23 4J011 AA05 AA08 BA04 BA08 JA01 JA13 JB02 JB06 JB08 JB27 JB30 PA46 PA96 PB15 PB40 PC07 4J026 AB28 AC22 AC23 AC35 BA24 BA25 BA29 BA30 BA32 BB01 CA02 DA02 DA07 DB03 DB08 DB09 DB14 FA03 GA08 4J027 AD02 AH03 BA06 BA08 BA13 BA14 CD07

Claims (6)

[Claims] 1. A composition comprising a polyacid amino acid and / or a salt thereof, having a structure in which primary particles are fused, and having an average particle diameter of 10
0-1000 μm, bulk density 0.1-0.6 g / ml
A water-absorbing material comprising water-absorbing resin particles. 2. The method according to claim 1, wherein the water-absorbent resin particles have at least one
The water-absorbent material according to claim 1, which is obtained by reacting a polyacid amino acid (A-1) having two ethylenically unsaturated double bonds with an ethylenically unsaturated compound (B). 3. The method according to claim 1, wherein the water-absorbent resin particles are reacted with an ethylenically unsaturated compound (B) in the presence of a polyacidic amino acid (A-2) having no ethylenically unsaturated double bond in the molecule. The water-absorbing material according to claim 1, which is obtained by: 4. A polyacid having at least one ethylenically unsaturated double bond in a molecule thereof in the presence of a phosphate ester surfactant represented by the following general formula (1): 3. The water-absorbing material according to claim 1, which is obtained by reacting the amino acid (A-1) with the ethylenically unsaturated compound (B). Embedded image [Wherein, R ¹ is an alkyl group having 8 to 30 carbon atoms,
Or an alkylaryl group, n represents an integer of 1 to 30, R ² represents a hydroxyl group or R ¹ O— (CH ₂ CH ₂ O) _n
-(R ¹ and n are the same as described above). ] 5. A water-absorbent resin particle comprising a phosphate ester surfactant represented by the following general formula (1) and a polyacid amino acid (A-A) having no ethylenically unsaturated double bond in the molecule.
4. The water-absorbing material according to claim 1, which is obtained by reacting an ethylenically unsaturated compound (B) in the presence of 2). Embedded image [Wherein, R ¹ is an alkyl group having 8 to 30 carbon atoms,
Or an alkylaryl group, n represents an integer of 1 to 30, R ² represents a hydroxyl group or R ¹ O— (CH ₂ CH ₂ O) _n
-(R ¹ and n are the same as described above). ] 6. The water-absorbent resin particles contain the phosphate ester-based surfactant in an inert solvent containing the phosphate ester-based surfactant represented by the following general formula (1), A polyacidic amino acid (A-1) having at least one ethylenically unsaturated double bond and / or a polyacidic amino acid (A-2) having no ethylenically unsaturated double bond, an ethylenically unsaturated compound (B ) And an aqueous solution containing a crosslinking agent and a radical initiator, and subjecting the polymer particles obtained by the water-in-oil type reverse phase suspension polymerization to a surface crosslinking treatment. The water-absorbing material according to any one of claims 1 to 5. Embedded image [Wherein, R ¹ is an alkyl group having 8 to 30 carbon atoms,
Or an alkylaryl group, n represents an integer of 1 to 30, R ² represents a hydroxyl group or R ¹ O— (CH ₂ CH ₂ O) _n
-(R ¹ and n are the same as described above). ]