JPH01148338A - Manufacturing method of microcapsules - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] This invention relates to a method for producing microcapsules using coacervation of hydrophilic colloids.

[Conventional technology]

A complex coacervage method using two types of hydrophilic colloids, at least one of which has gelling properties, is known as one of the means for microencapsulating hydrophobic substances. The details are known from US Pat. No. 2,800,457, etc., and the outline of the process is as follows.

(1) A hydrophobic liquid is emulsified and suspended in a hydrophilic colloid solution. or solid particles, into suspension.

(2) Mix an aqueous solution of a hydrophilic colloid with an opposite charge to the above hydrophilic colloid and the suspension of (1), dilute with water and
(Adjustment causes coacervation.

This causes colloidal coacervate droplets to adhere around the hydrophobic substance and form a wall film.

(3) Cooling to below the gelling temperature of the colloid.

(4) Add a curing agent and cause a curing reaction of the wall film by adjusting pi.

Among the above-mentioned hydrophilic colloids, examples of anionic colloids include gum arabic, sodium alginate, agar, carrageenan, and carboxymethyl cellulose. Casein, gelatin, albumin, collagen, etc. are used as cationic substances.

[Problem that the invention seeks to solve]

Coacervate droplets usually accumulate around a hydrophobic substance that serves as the core substance and form a wall film, but coacervate droplets may not adhere to a particularly strongly hydrophobic substance and a wall film may not be formed. .

[Means for solving problems]

The present invention was made to solve these problems, and when depositing coacervate droplets, an interface having a plurality of hydrophilic groups of carboxyl groups, amino groups, amide groups, or guanidino groups in one molecule is used. It is characterized by the addition of an active polymer compound.

The surface-active polymer compound may have one type of hydrophilic group,
There may be two or more types. The surface-active polymer compound may contain two or more carboxyl groups, amino groups, amide groups, or guanidino groups; for example, it may contain one amino group and one guanidino group. Further, as long as it contains two or more of these hydrophilic groups, it may further contain other hydrophilic groups. Preferred surface-active polymer compounds are those that contain five or more of these hydrophilic groups.

As such a polymer compound, one having the following structure is preferable. It is also preferable that the above carboxyl group is replaced with an amino group, an amide group or a guanidino group. Preferred examples of compounds containing carboxyl groups include copolymers of methacrylic acid and olefin, and salts of these compounds are more effective.

The surface-active polymer compound may be added before the hardening reaction of the wall film occurs. For example, it may be mixed in advance with a hydrophilic colloid solution or a hydrophobic liquid, or this mixture may be diluted with water or adjusted to pH The amount of surface-active polymer compound added may be added before, during or after the adjustment, as long as the coacervate droplets adhere to the core material.
This varies depending on the hydrophobicity of the core material.

The method of the present invention is particularly effective in cases where the core substance has strong hydrophobicity and conventional methods do not allow coacervate droplets to adhere and no wall film to form. An example of such a core substance is
Examples include paraffin wax and silicone oil.

The hydrophilic colloid is preferably one that can be easily insolubilized with a curing reagent such as aldehyde or beeswax, and suitably has an amino group, an amide group, a carboxyl group, or the like.

[Effect]

Coacervate droplets and hydrophobicity can be achieved by adding a surface-active polymer compound having a plurality of hydrophilic groups, such as carboxyl, amino, amide, or guanidino groups in one molecule, to the coexisting solution of coacervate droplets and a hydrophobic core substance. The affinity with the core material is improved, and coacervate droplets are attached around the core material to form a wall film.

〔Example〕

30 parts of 10% gelatin aqueous solution with isoelectric point 8 and JIS 12
A small amount of polyoxyethylene alkyl phenyl ether was added as an emulsifier to a mixture of 15 parts of 5'''F paraffin wax, and the mixture was stirred at a temperature of 60°C to form a 0/W type emulsion.To this, a 10% aqueous gum arabic solution was added. 30
part was added and cooled to 40°C.

One part of Disparon #1860 (manufactured by Kusumoto Kasei ■), which mainly consists of a salt of a long-chain polyaminoamide and a high-molecular acid polyester, was dispersed in 140 parts of water at 40°C and added to the above emulsion.

While stirring, add a 10% acetic acid aqueous solution dropwise to bring the pl+ to 4.
Adjusted to.

The liquid was cooled to 20°C while stirring, and 1 part of 35% formaldehyde was added. Furthermore, after adjusting the pH to 9 by dropping 10% sodium hydroxide,
The temperature was raised to 0°C to harden the capsule wall film.

As a result, paraffin wax-containing polynuclear microcapsules with a particle size of 10 to 50 nm were obtained.

On the other hand, when the same procedure as above was followed except that Disparon #1860 was not added, the cured droplets of gelatin-gum arabic and the paraffin wax particles were completely separated.

〔Effect of the invention〕

By the method of the present invention, even in the case of a strongly hydrophobic substance, coacervate droplets can be accumulated around the substance to form a capsule wall membrane. It can also be applied to the preparation of microcapsules by a simple coacervation method in which coacervate droplets are precipitated by adding alcohol to a hydrophilic colloid aqueous solution to make it a poor solvent.

Patent applicant: Nippon Kokan Co., Ltd. Agent: Patent Attorney Masahiro Kuninaka

Claims (1)

[Claims] In the method for manufacturing microcapsules using the complex coacervation method of hydrophilic colloids, when a strongly hydrophobic substance is used as the core material, one hydrophilic group such as a carboxyl group, an amino group, an amide group, or a guanidino group is added to the core material. A method for producing microcapsules characterized by adding a plurality of surface-active polymer compounds in the molecule to cause coacervate droplets to adhere around a core substance to form a wall film.