JPH01207133A - Porous microcapsule - Google Patents

Abstract

PURPOSE:To prevent a microcapsule from transformation to jelly material after absorbing water, and to enable to adjust its water retention, i.e., its controlled release, freely by encompassing a polymer absorbent 1 such as a crosslinked polymer of polyacrylic acid, etc., with a hydrophilic porous wall material 2. CONSTITUTION:Water is absorbed by a powdery or granular polymer absorbent such as a crosslinked polymer of polyacrylic acid such as 'Aquakeep 4S (R)', and generated gel is mixed with amine, alcohol acid, or a compd. contg. an active hydrogen such as mercaptan. The mixture is dispersed uniformly in a water-insoluble org. solvent. An interfacial poycondensation (plyaddition) is carried out by adding an isocyanate or an epoxy compd., etc., to the liquid dispersion. After separating formed capsule-shaped product encompassing the polymer absorbent by filtration, etc., porous microcapsules having 5mum-10mm particle size are obtd. by drying the separated produce. Thus, porous microcapsules are obtd. without impairing water absorption of encompassed polymer absorbent. Problems concerning jellification after absorbing water are eliminated, and the water retention of the product is optionally adjustable. Accordingly, the product is utilizable as a release controllable carrier, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to porous microcapsules that have both excellent water absorption and water retention properties. It is a capsule that can be used for general purposes as a water absorbent or carrier for various modifying additives.

Conventional technology Polymer absorbent materials (or superabsorbent resins) have traditionally been used as materials for sanitary hygiene products such as diapers, diaper covers, and napkins, but this type of absorbent material gels when it absorbs water. , which takes advantage of the property that once water is incorporated into the gel, it is difficult to flow out of the gel. However, conventional polymeric absorbent materials have the disadvantage that they turn into a jelly-like state after absorbing water, resulting in a sticky state that causes discomfort to the wearer.

In addition, this type of polymeric absorbent material is expected to be used as a carrier for soil conditioners and various sustained-release compositions (e.g. deodorants, insect repellents, rust preventives, etc.), and some of them are in practical use. This utilizes the water-retentive property of the polymer absorbent material, that is, the property of retaining absorbed water and gradually releasing it. However, in this case, in addition to the above-mentioned problem of formation into a jelly, there is also the difficulty of not being able to freely control sustained release properties, which naturally limits its use.

Problems to be Solved by the Invention The present invention has been made in order to expand the uses of this type of polymer absorbent material by solving the above-mentioned problems related to the water absorption and water retention properties of polymer absorbent materials. .

Means for solving the problem, that is, the present invention, as shown in the schematic cross-sectional view of FIG. Regarding capsules.

When the polymeric absorbent material (1) comes into contact with water or an aqueous medium, it rapidly swells and gels, exhibiting water-retentive properties. Known polymer absorbent materials can be used.

Examples of this type of polymer absorbent include crosslinked polymers of polyacrylic acid, crosslinked polymers of polyvinyl alcohol, copolymers of starch and acrylic acid, and acrylic copolymers containing acrylic acid as the main component. be done.

In addition, commercially available superabsorbent resins, such as Aqua Keep 4S and Aqua Keep 103H (manufactured by Steel Chemical Co., Ltd.),
Sumikagel 58 and Igetagel 5S (manufactured by Sumika Kagaku Co., Ltd.)
, 5GP502S (manufactured by Henkel Japan), and Sunwet IM-300 (manufactured by Sanyo Chemical Co., Ltd.) can also be used as appropriate.

The form and size of the polymer absorbent material (1) contained in the capsule are not particularly limited, but the particle size is usually about 1 μm.
1 mm powder or granules.

In this case, the particle size means the average value (volume average) of the primary particle size (unagglomerated material) measured using a Coulter Counter (manufactured by Coulter Inc.) (the same applies hereinafter).

In addition, the amount of the polymer absorbent (1) included is not limited,
It may be selected as appropriate depending on the type of absorbent, purpose of use, size of capsule, etc.

The wall material (2) constituting the shell wall of the porous microcapsule according to the present invention is a hydrophilic porous polymer, which facilitates water absorption into the polymer absorbent material (1), and also allows the absorbent material to retain water. While separating the absorbent material from the outside, it also suppresses water separation from the absorbent material.

Examples of such hydrophilic porous polymers include water-soluble acrylic seventh polymer copolymers, polycondensates of incyanates and amines, alcohols, or polyvalent thiols, and epoxy compounds and amines, alcohols, or polyvalent thiols. Examples include polycondensates, polycondensates of carboxylic acids, acid anhydrides, or their chlorides, and amines or alcohols. Water-soluble acrylic salts include acrylic acid, methacrylic acid, droxyethyl acrylate or methacrylate, hydroxypropyl acrylate or methacrylate, metal salts of acrylic acid or methacrylic acid, glycidyl methacrylate, acrylonitrile,
vinylpyrrolidone, acrylamide methylpropanesulfonic acid, diacetone acrylamide, acrylamide,
Examples include maleic anhydride and butoxyethyl acrylate.

Incyanates include aliphatic, aromatic or heterocyclic polyisocyanates, such as 1.4-tetramethylene diisocyanate, 1.6-hexamethylene diisocyanate, 1.12-dodecane diisocyanate, 1.3- or 1.3-cyclohexane. 4-diisocyanate and mixtures thereof, l-incyanato-3,3,
5-1-Dimethyl-5-isocyanatomethyl-cyclohexane, 2,4- or 2,6-hexahydrotoluylene diisocyanate, hexahydro-1,3- or 1,4-phenylene diisocyanate, perhydro-
2,4′-and/or 4.4°-diphenylmethane diisocyanate, diphenylene-2,4-and/or
or 4.4'-diisocyanate naphthalene, 1.5
'-Diisocyanate triphenylmethane 4.4'', 4
"-triisocyanate, polyphenylpolymethylene polyisocyanate, m- and p-isocyanatophenylsulfonyl isocyanate, carbodiimide-containing polyisocyanate, aryl polyisocyanate, allophanate group-containing polyisocyanate, biuret group-containing polyisocyanate, ester group-containing polyisocyanate Examples include isocyanates.

Amines include aliphatic primary or secondary diamines, aromatic diamines and polyamines, such as ethylene-1,2
-diamine, bis(3-aminopropyl)-amine, hydrazine and its salts, hydrazine-2-ethanol,
Bis(2-methylaminoethyl)methylamine, 1.4
-diaminocyclohexane, 3-amino-1-methylaminopropane, 1,4-diamino-n-butane,! ,6
-Diamitsu n-hexane, ethylene-1,2-diamine-N-ethyl-sulfonic acid, l-aminoethylene-1
,2-diamine, (bis-N,N'-aminoethyl)-
Ethylene-1,2-'; Examples include amine, m-xylene diamine, p-xylene diamine, and the like.

Alcohols include aliphatic or aromatic polyhydric alcohols, hydroxy polyesters, hydroxy polyalkylene ethers, etc., such as catechol, resorcinol,
Hydroquinone, 1,3-dihydroxy-5-methylbenzene, 3,4-dihydroxy-1-methylbenzene,
3.5-dihydroxy-1-methylbenzene, 2.4-
Dihydroxyethylbenzene, 1.3-naphthalenediol, 1.5-naphthalenediol, 2.7-naphthalenediol, 2.3-naphthalenediol, o.

0′-biphenolp, p″-biphenol, 1.1
'-Bisnaphthol; bisphenol A, 2.2'-bis(4-hydroxyphenyl)-butane, 2.2'-bis(4-hydroxyphenyl)-isopentane, 1.1
'-(4-hydroxyphenyl)-cyclopentane, 1
．． 1'-bis(4-hydroxyphenyl)-cyclohexane, 2,2'-bis(4-hydroxy-3-methylphenyl)-propane, bis(2-hydroxyphenyl)
-methane, xylylene diol, ethylene glycol,
1.3-propylene glycol, 1.4-butylene glycol, l,5-bentanediol, l,6-hebutanediol, 1.7-hebutanediol, 1.8-octanediol, l,l,l- Trimethylolpropane, hexanetriol, pentaneerythritol, glycerin, sorbitol, hydroxy polyesters obtained from the above polyhydric alcohols and polyhydric carboxylic acids, and the above polyhydric alcohols and alkylene oxides (e.g. bisphenol A glycidyl ether and 1,3-propylene). Examples include hydroxypolyalkylene ethers obtained from glycols, etc.).

Examples of polyvalent thiols include thioglycol and condensation products of thioglycol.

Epoxy compounds include aliphatic glycidyl esters such as glycidyl ether, glycerin triglycidyl ether and polyallyl glycidyl ether, diglycidyl ether of bisphenol A, triglycidyl ether of trihydroxyphenylpropane, and 4.4'-
Examples include glycidyl ether/ester mixtures such as diglycidyl ether ester of bis(4-hydroxyphenyl)valeric acid.

Examples of carboxylic acids include malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, maleic acid, isophthalic acid, gluconic acid, etc., and examples of acid anhydrides include maleic anhydride, succinic anhydride, phthalic anhydride, Examples include benzoic anhydride.

The water permeability of the wall material (2) and the properties that separate the water-retaining polymer absorbent material (1) from the outside, such as porosity, thickness and strength of the shell wall, heat resistance, etc., depend on the intended use of the microcapsules.
It can be adjusted by appropriately selecting the types of components forming the hydrophilic porous polymer and the conditions for producing the polymer.

For example, when an isocyanate polycondensate is used as a wall material, the porosity of the shell wall can be increased by increasing the production reaction temperature by interfacial polymerization of the shell wall to generate CO1.

The thickness of the shell wall and the size of the shell, that is, the size of the porous microcapsules, are not particularly limited, and can be appropriately selected depending on the purpose of use of the microcapsules and the material and characteristics of the wall material (2). However, the thickness is usually about (L1 μm to 5 μm).
00 μm, and the size is approximately 5 μm"l Omm. The method for producing porous microcapsules according to the present invention is not particularly limited, and any known encapsulation method may be used, but a particularly preferred method is There are two methods:

The first method involves absorbing water into the above-mentioned polymeric absorbent material in powder or granular form, mixing the resulting gel with the above-mentioned active hydrogen-containing compound such as an amine, alcohol, acid, or mercaptan; The polymer absorbent material is uniformly dispersed in a water-soluble organic solvent, and a component capable of polycondensation with the active hydrogen-containing compound, such as the above-mentioned incyanate or epoxy compound, is added to the dispersion liquid to perform an interfacial polycondensation reaction. This method is characterized by separating the capsule-like product containing the molecule by filtration or the like, and then subjecting it to drying.

Examples of the water-insoluble organic solvent include n-hexane, xylene, and a xylene/carbon tetrachloride mixed solvent.

The interfacial polycondensation reaction temperature depends on the types of reaction components and is not particularly limited, but is usually about 20 to 80°C.

The capsule-shaped product separated by filtration or the like is washed with a volatile organic solvent such as n-hexane, if desired, and then subjected to drying.

The drying process is usually about 40-100℃ after air-drying at room temperature.
This removes the water impregnated and encapsulated in the capsule.

A second method suitable for producing porous microcapsules according to the invention is to mix the aforementioned polymeric absorbent material in powder or granular form with water and at least two of the aforementioned water-soluble acrylic monomers to form a porous microcapsule. The gel is uniformly dispersed in the above-mentioned water-insoluble organic solvent, and then in-situ (irl 5
This method is characterized by carrying out a copolymerization reaction, separating the capsule-shaped product containing the polymer absorbent by filtration, etc., and then subjecting it to drying.

The in-situ copolymerization reaction temperature depends on the types of reaction components, etc., and is not particularly limited, but is usually about 40 to 150℃.
It is °C.

Porous microcapsules can be obtained by subjecting the capsule-shaped product produced by this reaction to the same post-treatment as in the first production method described above.

Hereinafter, the present invention will be explained by examples.

Example 1 Aqua Keep 4S (polymer absorbent manufactured by Steel Chemical Co., Ltd.) 0.
Rheodol 5po-10L (oil-soluble surfactant manufactured by Kao Corporation) 109 and hexamethylene diamine 159 were mixed into a gel prepared by mixing 59 and 250 g of pure water, and the mixture was dispersed in 1000 g of n-hexane. ,600r
Stirring was carried out for 15 minutes under pm conditions.

20 g of hexamethylene diisocyanate was added at once to this dispersion, and the reaction was carried out at room temperature for 1 hour. The temperature of the system was raised to 60°C to form a capsule shell, and stirring was continued at this temperature for 2 hours to react. completed.

After the reaction mixture was cooled, it was subjected to filtration treatment, thoroughly air-dried, and then heat-treated in a dryer (80°C, 5 hours) to completely remove the moisture inside the capsules, thereby reducing the particle size. Target 0, l Rava porous microcapsule 30y'km.

The obtained porous microcapsules absorbed 8 times their own weight of water (corresponding to 500 to 600 times the amount of water per water-absorbing agent), and even in this water-absorbed state, they were free of moisture and exhibited a smooth texture. The polymeric water absorbing agent is gel-like,
The microcapsules are easy to handle, although they have the disadvantage that water is moved by finger pressure.

Example 2 Aqua Keep 103H (polymer absorbent manufactured by Steel Chemical Co., Ltd.)
A gel prepared by mixing 0.59, 200 g of water, 1 g of water-soluble triacrylic formal, 50 g of hydroxyethyl methacrylate, and 0.5 g of ammonium persulfate was dispersed in 1000 g of xylene, and the reaction was carried out at 80°C for 5 hours to form a capsule shell. was formed.

After cooling the reaction mixture, it was subjected to a filtration treatment, thoroughly air-dried, and then heat-treated in a dryer (60°C, 5 hours) to obtain porous microcapsules with a particle size of 50 to 2000μ. Ta.

The resulting porous microcapsules remained dry until they absorbed 10 times their own weight of water.

Example 3 Super water-absorbent resin powder mainly composed of polyacrylic acid-acrylonitrile (average particle size 5 to 10 μm) 1 g, water 2
A gel prepared by mixing 00 g of metaxylene diamine 109 and a 3-mole adduct of nonylphenol-ethylene oxide 19 was dispersed in 500 g of xylene, and after stirring vigorously for 10 minutes, Desmodur L-75 (fragrant A solution prepared by diluting 15 g of incyanate) in 50 g of xylene was added, stirred at 25°C for 30 minutes, and the reaction was continued at 60°C for 3 hours.

The reaction mixture was filtered and then diluted with n-hexane 10
Washing was carried out twice using 0 mff, and the obtained capsules (particle size 10-100 μm) were subjected to heat treatment (60° C. for 15 hours) to obtain 30 g of porous microcapsules.

Example 4 Sumikagel (polymer absorbent manufactured by Sumima Kagaku Kogyo Co., Ltd.)
19. A gel prepared by mixing 5 g of polyethyleneimine 5P-600 (manufactured by Nippon Shokubai Kagaku Kogyo Co., Ltd.) and 300 g of water was mixed with a xylene/carbon tetrachloride mixed solvent (specific gravity 1) 5
009 with vigorous stirring, and 50 g of Coronate EH (aliphatic incyanate manufactured by Nippon Polyurethane Co., Ltd.) 159 in a xylene/carbon tetrachloride mixed solvent was added to the dispersion.
Add the solution dissolved in
I did it for an hour.

The reaction mixture was filtered, washed, and then heat treated (60° for 0.5 hours) to obtain porous microcapsules 259.

Example 5 Aqua Keep 4S 1g, triacrylic formal 1g
, acrylonitrile 59, acrylamide 59, hydroxypropyl acrylate 109, V-50 (Azobis reaction initiator manufactured by Wako Pure Chemical Industries, Ltd.) 0.29 and water 2
00g of gel prepared by mixing 500g of n-hexane.
The mixture was dispersed in water and the reaction was carried out under heating and reflux for 6 hours.

After the reaction mixture was filtered, it was placed in a dryer for 6 hours.
20 g of porous microcapsules were obtained by drying at 0° C. for 5 hours.

Effects of the Invention Since the porous microcapsule according to the present invention has a structure in which a polymer absorbent material is enclosed and separated by a hydrophilic porous wall material,
The above-mentioned problems related to jelly formation and water retention of the absorbent material caused by water absorption can be solved without impairing the excellent water absorbency of the polymer absorbent material.

Therefore, the porous microcapsules according to the present invention can impregnate and encapsulate water and various active ingredients (e.g., medicines, agricultural chemicals, deodorant fragrances, rust preventives, fertilizers, etc.) as water-absorbing agents for sanitary hygiene products such as diapers and napkins. It can be used in a wide range of fields as a sustained release carrier.

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional view of a porous microcapsule according to the present invention. (1) indicates a polymer absorbent material, and (2) indicates a hydrophilic porous wall material. Patent applicant: Matsumoto Yushi Pharmaceutical Co., Ltd. Agent: Patent attorney: Aobai Ao and two others Figure 1: JLJ Emaiko sword figure's talent

Claims (1)

[Scope of Claims] 1. Porous microcapsules comprising a polymeric absorbent material enclosed in a hydrophilic porous wall material. 2. The porous microcapsule according to claim 1, which has a particle size of 5 μm to 10 mm. 3. The polymeric absorbent material according to claim 1, wherein the polymeric absorbent material is a crosslinked polymer of polyacrylic acid, a crosslinked polymer of polyvinyl alcohol, a copolymer of starch and acrylic acid, or a copolymer of acrylic acid and a polyfunctional monomer. Porous microcapsules. 4. The hydrophilic porous wall material is a copolymer of a water-soluble acrylic monomer, a polycondensate of an isocyanate and an active hydrogen-containing compound, a polycondensate of an epoxy compound and an active hydrogen-containing compound, or a polycondensate of a carboxylic acid and an amine or alcohol. The porous microcapsule according to claim 1, which is a polycondensate of. 5. Let powdered or granular polymer absorbent absorb water,
The resulting gel is mixed with an active hydrogen-containing compound, the mixture is uniformly dispersed in a water-insoluble organic solvent, and a component capable of polycondensation with the active hydrogen-containing compound is added to the dispersion to cause an interfacial polycondensation reaction. 5. The method for producing porous microcapsules according to any one of claims 1 to 4, wherein the product is separated and then subjected to a drying treatment. 6. Mixing a powdered or granular polymer absorbent with water and at least two types of copolymerizable monomers, uniformly dispersing the resulting gel in a water-insoluble organic solvent, and performing an in-situ copolymerization reaction; 5. The method for producing porous microcapsules according to claim 1, wherein the product is subjected to a drying treatment after being separated.