JPS60824A - Manufacture of microcapsule - Google Patents

Abstract

PURPOSE:To simplify the manufacturing process of a microcapsule contg. a hydrophobic core substance, and to obtain the microcapsule of high quality by using natural and/or synthetic clay minerals having a gelling function as an emulsifying and dispersing agent of the hydrophobic core substance. CONSTITUTION:The natural or synthetic clay substance such as a mont-morillonite group clay substance having a gelling function are used as an emulsifying and dispersing agent of a hydrophobic core substance in the manufacture of a microcapsule by polymerizing a film-forming monomer on the surface of the hydrophobic substance which is dispersed in a hydrophilic dispersion medium. The mixing ratio of the hydrophilic substance contg. clay minerals to the hydrophobic core substance contg. the monomer is regulated preferably to from 1:2 to 50:1 weight ratio. In addition, the mixing ratio of the hydrophobic core substance to the monomer is regulated to from 1:1 to 19:1. The water content of the hydrophilic dispersion medium to contain the clay minerals is regulated to about >=60wt%. In this way, the microcapsule of high quality can be manufactured with the simple method.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing microcapsules containing a hydrophobic core material, which simplifies the manufacturing process and allows high quality microcapsules to be obtained.

Generally, methods for producing microcapsules are classified into physical/mechanical methods, physicochemical methods, and chemical methods.

Physical/mechanical methods include the fluidized bed method, spray granulation method, pan coating method, etc., physicochemical methods such as the conflation core cell bathing method, and submerged drying method, and chemical methods include the interfacial weight granulation method. Examples include a condensation method and an in 5 situ method.

The method of the present invention involves reacting a film-forming monomer and a polymerization initiator on the surface of a hydrophobic core substance, and in
It belongs to the 5itu method.

Conventionally, in this in-situ method, various surfactants and water-soluble polymers have been used as emulsifying and dispersing agents.

Specific examples include stearic acid, soaps such as sodium rosinate, anionic surfactants such as sodium lauryl sulfate, sodium polyoxyethylene lauryl ether sulfate, sodium nooctylsulfokophosphate, stearyl chloride, etc. There are cationic surfactants such as trimethylammonium, nonionic surfactants such as oxyethylene alkyl ether, and polyoxyethylene lupitan fatty acid ester.

Water-soluble polymers include natural polymer compounds such as gum arabic, sodium alginate, gelatin, sodium carboxymethyl cellulose, hydroxyethyl cellulose, and methyl cellulose, and their derivatives, calgexivinyl polymer, sodium polyacrylate, polyvinyl alcohol, and polyvinyl These included synthetic water-soluble polymer compounds such as pyrrolidone.

However, conventional in-process methods using surfactants and water-soluble polymers
In the case of the 5 itu method, it is difficult to remove surfactants and water-soluble polymers remaining in the membrane material or on the membrane surface, and a large amount of engineering and effort is required during washing and cleaning, leading to increased costs. Furthermore, there were quality problems such as elution of the core substance, incomplete encapsulation, and reduction in membrane density.

An object of the present invention is to provide a novel method for producing microcapsules that eliminates the drawbacks of such conventional methods. From this point of view, as a result of intensive research, the present inventors have discovered that by using natural and/or synthetic clay minerals with celifying ability as emulsifying and dispersing agents instead of surfactants and water-soluble polymers in conventional methods. It was discovered that microcapsules can be produced, leading to the present invention.

The present invention is directed to a method for producing microcapsules in which a film-forming monomer is polymerized on the surface of a hydrophobic core material dispersed in a hydrophilic dispersion medium. The present invention relates to a method for producing microcapsules characterized by using/or synthetic clay minerals.

The clay minerals having gluing ability used in the present invention are mainly clay minerals of the montmorillonite group such as montmorillonite, saponite, hectorite, beidellite, nontronite, and sauconite, or the above-mentioned clay minerals. Bentonite, acid clay, etc., especially synthetic hectorite (trade name: Laponite, Laporte I)
(manufactured by Lim-lted, Inc.) is preferred. These clay minerals have emulsifying and dispersing properties and stabilize suspensions, and exhibit emulsifying and dispersing properties equivalent to or higher than those of conventional surfactants and water-soluble polymers. In particular, synthetic hectorite has high emulsifying and dispersing properties.

In the present invention, such clay minerals are present in the residual aqueous medium at 0.0%.
The content is preferably 1% by weight or more, and more preferably 0.24% or more from the viewpoint of ease of emulsification and dispersion and quality of microcapsules. The upper limit of the content is determined by the viscosity and stability of the system, as well as the dispersion equipment, but is generally kept at 3 ft% or less. If the clay mineral content is too small, the emulsification and dispersion effects will be insufficient, and if it is too large, the viscosity will be too high and there may be a risk of precipitation.

The hydrophilic medium containing the clay mineral is one that contains water by weight of about 60% or more, and includes lower alcohols such as methanol, ethanol, and isonoropanol, ethylene glycol, propylene glycol, glycerin, 1,3-butylene glycol, sorbitol, and glucose. Polyhydric alcohols such as sodium chloride, sodium carbonate, sodium metaphosphate, sodium dihydrogen phosphate, inorganic salts such as sulfur and lithium sulfate, acids such as hydrochloric acid, phosphoric acid, acetic acid, sodium hydroxide, calcium hydroxide , a water-soluble substance can be added, such as a base such as aqueous ammonia.

The water in the hydrophilic medium must be about 60% by weight or more to ensure the formation of glue by water swelling of the clay mineral.

In the present invention, the mixing ratio of the hydrophilic substance containing the clay mineral and the hydrophobic core substance containing the monomer is determined from the viewpoint of ease of emulsification and dispersion and/or stability of the system; :2 to 50=1, more preferably 1:1 to 25:1.

In the present invention, the hydrophobic core substance to be encapsulated in the microcapsules is not particularly limited and may be selected depending on various purposes, but the following substances are exemplified. Oils and fats such as safflower oil, soybean oil, olive oil, cottonseed oil, castor oil, palm oil, sesame oil, beef tallow, waxes such as beeswax, carnauba wax, spermaceti wax, lanolin, candelilla wax, and jojoba oil, RYU F7JI NOE RAFFIN , liquid polyisobutylene, vaseline, noya rough-in, microcrystalline wax, squara/,
Hydrocarbons such as silylistan, fatty acids such as myristic acid, palmitic acid, stearic acid, oleic acid, 12-hydroxystearic acid, isostearic acid, lanolin fatty acid, coconut oil fatty acid, cetyl alcohol, stearyl alcohol, behenyl alcohol, oleyl alcohol, Lanolin alcohol, cholesterol, phytosterols, 2-octyldodecanol, higher alcohols such as isostearyl alcohol, inglovir myristate, butyl stearate, hexyl laurate,
Esters such as myristyl myristate, octyldodecyl myristate, oleyl oleate, octyldodecyl oleate, and cetyl lactate, silicone oils such as dimethylpolysiloxane and methylphenylsiloxane, and even butylhydroxane, which is a component soluble in these substances. '/7 = 7-ol, antioxidants such as butylated hydroxytoluene, preservatives such as salicylic acid, methyl guraoxybenzoate, oil-soluble vitamins such as vitamins A, D, and E, and other fragrances. , dyes, etc.

In the present invention, the mixing ratio of the hydrophobic core material and the hexamer is in the range of 1:1 to 19=1, more preferably in the range of 3:2 to 9:1. When the hydrophobic core substance is smaller than the above range, microcapsules themselves can be formed, but the amount contained is too small to fully demonstrate their original usefulness during use; There is a strong possibility that it will be difficult to form a microcapsule film, or that even if it is formed, it will be very weak.

The film-forming monomers used in the present invention may be known ones, such as acrylic acid and its esters (methyl acrylate, etc.), methacrylic acid and its esters (methyl methacrylate, etc.), acrylonitrile, vinyl acetate, vinyl ether (butyl vinyl ether, etc.). ), styrene and its derivatives (α-methylstyrene, etc.), polyethylene glycol dimethacrylate (polymerization degree 1-8
), divinylbenzene, etc. These can be used alone or in a mixture of two or more, but in particular methyl methacrylate accounts for 500% of the total monomer components.
A high-quality capsule membrane can be obtained by using a higher proportion by weight, so it is advantageously used.

The polymerization initiator used in the present invention is preferably one that is soluble in the monomer.5 For example, organic peroxides such as benzoyl peroxide, lauroyl peroxide, and t-butyl peroxide, azobisisobutyronitrile (AIBN), etc. , azo-based initiators such as azobiscyclohexanecardenitrile, and the like.

The addition ratio of the polymerization initiator to the monomer used in the present invention is from 0.1% by weight to 5% by weight of the film-forming monomer.
The amount is preferably 0.5% to 3% by weight.

The present invention will be explained in more detail with reference to Examples below, but the present invention is not limited thereto.

Example 1 (Heavy liquid part) After A was dissolved at 60°C, B was added to cool it to 40n at 17°C. This was gradually added to C, whose pH was adjusted to 5 and the temperature was adjusted to 40° C., under a nitrogen atmosphere to perform rough emulsification, and further, using a homomixer at 8000 rpm.

Emulsification and dispersion were performed for 3 minutes. This suspension was transferred to a reaction vessel equipped with a reflux condenser, a stirrer, a thermometer, and a nitrogen inlet tube, and a polymerization reaction was carried out at 60° C. for 6 hours to produce microcapsules. The slurry in which the microcasselles were dispersed was centrifuged to remove saponite, followed by p-filtration, washing, and drying to obtain the desired microcapsules.

Example 2 After melting and mixing A and B at 20°C, they were gradually added to C whose - was adjusted to 7 in a nitrogen atmosphere to coarsely emulsify, and further using a homomixer at 110,000 rpm. Emulsification 1 dispersion for 1 minute was carried out in a reaction vessel similar to Example 1.
A polymerization reaction was carried out at ℃ for 8 hours to produce a microcasselle. The slurry was centrifuged, washed, and dried to obtain the desired microcassette.

Example 3 (Parts by weight) A is dissolved at 80°C, then cooled to 60°C, and B is added. This was adjusted to -5 in a nitrogen atmosphere and gradually added to C whose temperature was adjusted to 60°C to perform rough emulsification, and then soo using a homomixer.

emulsification and dispersion for 2 minutes at rpm. After transferring the mixture to the same reaction vessel as in Example 1, a polymerization reaction was carried out at 70° C. for 6 hours to produce microcapsules. The slurry was centrifuged, filtered, washed, and dried to obtain the desired microcasselle.

Example 4 (parts by weight) Microcapsules were prepared as in Example 20.

As mentioned above, all of the microcapsules have high thermal and mechanical stability, no elution of hydrophobic core substances, and the best advantage is that they can be easily and completely separated and washed.

These effects are highly useful industrially as a general microcapsule manufacturing method. In particular, when used as cosmetics such as powder and emulsified fan del gel, various textures can be imparted by changing the type of hydrophobic core substance:::M even within the same dosage form. Beneficial.

Patent applicant? −La Kasei Kogyo Co., Ltd. Agent: Patent attorney Asamichi Kato

Claims (1)

[Scope of Claims] 1) Hydrophilic dispersion 1 In a method for producing microcapsules in which a film-forming monomer is polymerized on the surface of a hydrophobic core substance dispersed in a certain hydrophilic dispersion 1, caking as an emulsifying and dispersing agent for a hydrophobic core substance. 1. A method for producing microcapsules characterized by the use of natural and/or synthetic clay minerals having the following properties. 2) The manufacturing method according to claim 1, wherein the natural or synthetic clay mineral is a montmorillonite group clay mineral. 3) A ratio of the sum of the film-forming monomer and the hydrophobic core substance to the sum of the clay mineral and the hydrophilic dispersion medium is in the range of 2:1 to 1:50 by weight. The manufacturing method according to item 1 or 2. 4) The manufacturing method according to claims 1 to 3, wherein the ratio of the film-forming monomer to the hydrophobic core substance is in the range of 1=1 to 1:19. 5) The manufacturing method according to claims 1 to 4, wherein 60% by weight or more of the hydrophilic dispersion medium is water.