JPS5940501B2 - Manufacturing method of microcapsules - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing microcapsules, and in particular to a novel method for producing microcapsules of zinc methacrylate by impregnating and reacting pre-produced microcapsules of zinc oxide and/or zinc hydroxide with methacrylic acid. Regarding the law.

Although various methods have been proposed for producing microcapsules, successful microencapsulation may not be achieved depending on the properties of the core material.

For example, when zinc methacrylate, which is used as a crosslinking agent for solid golf balls, is microencapsulated as it is, it is difficult to obtain satisfactory microcapsules due to the high cohesive force of zinc methacrylate. The present invention provides a technique for microencapsulating the above-mentioned materials that are difficult or impossible to microencapsulate.

That is, the present invention impregnates methacrylic acid into microcapsules coated with water-insoluble zinc oxide and/or hydroxide with a wall material, and reacts the methacrylic acid with zinc oxide and/or zinc hydroxide inside the microcapsules. The present invention relates to a method for producing microcapsules of zinc methacrylate, which is characterized by the following. The microcapsules of zinc oxide and/or zinc hydroxide in the present invention are produced using a conventionally known method, such as a coacervation method from an aqueous medium or an organic solvent, an interfacial polymerization method, etc. good. The wall material to be coated with zinc oxide and/or zinc hydroxide may be appropriately selected depending on the type and properties of zinc oxide and/or zinc hydroxide, the properties of methacrylic acid, the microencapsulation method, and the like.

Preferably, methacrylic acid has excellent permeability into the capsule, such as carboxylic acids having an allyl group such as acrylic acid, methacrylic acid or ethacrylic acid, amides having an allyl group when permeating the capsule using an aqueous medium. It is a polymer containing at least one component of ester or nitrile. Cinnamic acid, crotonic acid, maleic acid, fumaric acid or esters thereof may be used partially in place of the allyl group-containing carboxylic acids. When producing zinc oxide and/or zinc hydroxide by the coagulation method using an aqueous medium, these polymers are used as water-soluble ones, such as sodium or ammonium salts of polycarboxylic acids, and their aqueous solutions are used. After dispersing the water-insoluble core material, the polymer may be made insolubilized by salt substitution, acidification, heating, or the like.

Of course, the material may be appropriately selected from conventionally commonly used gelatin, rosin, gum arabic, CMCl Sierra, PVAl, methyl cellulose, sodium alginate, etc.

For phase separation from an organic solvent, an appropriate material may be selected from ethyl cellulose, polyethylene, rubber, polyacrylic acid esters, polyvinyl acetate, and the like.

The microcapsules produced in this way are then impregnated with methacrylic acid without a solvent or in an appropriate solvent, such as a solvent that does not dissolve the wall material but dissolves methacrylic acid (usually a solvent whose main component is water). let Zinc oxide and/or zinc hydroxide reacts with methacrylic acid inside the microcapsules to form microcapsules of zinc methacrylate (normal salt). An example of manufacturing zinc methacrylate microcapsules by the method of the present invention will be described below.

Zinc oxide and/or zinc hydroxide with polyacrylic acid,
It is dispersed in an aqueous solution of a water-soluble salt of a polymer such as polymethacrylic acid, a copolymer of acrylic acid and acrylic ester, or a partially saponified product of polyacrylic ester, and then a water-soluble salt such as zinc acetate, aluminum acetate, calcium chloride, etc. A metal salt is added to make the polymer insoluble in water, and the resulting precipitate is washed with water to obtain microcapsules of a water-insoluble metal salt.
By immersing this in an aqueous solution of a required carboxylic acid, such as acrylic acid or methacrylic acid, microcapsules of a metal salt of carboxylic acid can be obtained.

This method is useful as a method for obtaining fine microcapsules of metal carboxylates, for example, when metal oxides and hydroxides are easily obtained as fine powders, but metal carboxylates are difficult to obtain as fine powders. It is particularly useful for producing microcapsules of zinc methacrylate useful as a crosslinking agent for rubber for solid golf balls. Example 1 Activated zinc white (particle size 0.1 μm or less) 500 g, tap water 1
kg and surfactant (Emalpin W: manufactured by Bayer AG)
2f! Place in a ball mill and run for 1 hour.

Add to this sodium polyacrylate (degree of polymerization 2700-750)
Add 5% aqueous solution 6009 of 0) and mix in a ball mill for an additional hour. Next, zinc acetate 2? Add aqueous solution 5009, mix for 1 hour, thoroughly wash the formed precipitate, and heat to 140°C.
The powder was dried and ground for 4 hours to obtain active zinc white microcapsules. Emulpin WO in this microcapsule 1401
．． 18.9 g of methacrylic acid containing 99% was added and reacted. The product is an aggregate of fine microcapsules,
X-ray diffraction confirmed peaks near 2θ-100 and 11. The above product was ground into 170 mesh;
20.4 parts per 100 parts by weight of rubber (JSRBROl)
0 and 60 weights were blended and kneaded using 6 inch rolls.

Claims (1)

[Claims] 1. Impregnating a microcapsule coated with zinc oxide and/or zinc hydroxide with a wall material with methacrylic acid, and reacting the zinc oxide and/or zinc hydroxide with methacrylic acid inside the microcapsule. A method for producing microcapsules of zinc methacrylate, characterized by: 2. The method according to item 1, wherein the wall material is a polymer containing at least one component of a carboxylic acid having an allyl group.