JPS5987034A - Aqueous suspension containing peculiar microcapsule - Google Patents

Abstract

PURPOSE:To enable the release of internal phase substance during drying, by bringing a microcapsule to be suspended in an aqueous medium to a coagulated polynuclear substance with a specific average particles size comprising the internal phase substance insoluble in water and liquid at an atmospheric temp. and a film material based on gelatine. CONSTITUTION:A microcapsule to be suspended in an aqueous medium is brought to a coagulated polynuclear one with an average diameter of 20-100mum comprising internal phase substance insoluble in water and liquid at an atmospheric temp. and a film material based on gelatione. For example, an equal wt. mixture of 0,0-diemthyl-S-(1,2-dicarboethyoxethyl)-dithiophosphate and 0,0-diisopropyl-S-benzyl-thiophosphate is used as the internal phase substance and the average particle size of dispersed oil is adjusted to 5mum to prepare the coagulated polynucler microcapsule with an average particle size of 50mum according to a known method. In the aqueous suspension containing this microcapsule, the internal phase substance is released during drying.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an aqueous suspension containing microcapsules that releases an internal substance when drying, and more particularly relates to an aqueous suspension containing microcapsules that are substantially insoluble in water and liquid at room temperature. An aqueous suspension containing microcapsules having a property of releasing an internal phase substance upon drying, characterized in that the average particle size of an agglomerated polynuclear type comprising a membrane material mainly composed of gelatin is 20 to ioDμ. This is related to suspension C.

Conventionally, when an aqueous suspension containing gelatin-based microcapsules is sprayed or applied onto an object and the water is evaporated and dried, the outside of the microcapsules contains 1, equivalent to the amount dissolved in the water. It was believed that there was an internal substance that did this.

Furthermore, when a surfactant is dissolved in water, it is common for internal phase substances to be eluted to the outside beyond their solubility in water due to the solubilization phenomenon; however, when drying, internal phase substances As a result of extensive research, the present inventors have discovered that water is essentially insoluble in water.
An aqueous suspension containing microcapsules of cohesive polynuclear type, which contains an internal phase material that is liquid at room temperature and has a membrane material consisting of gelatin and has an average particle size of 20 to 100 μm, is sprayed onto an object. Under the environment, when the water around the microcapsules and part of the water contained in the gelatin-based film evaporates on the surface of an object, and the spray liquid containing the microcapsules dries, He discovered that microcapsules release internal substances by squeezing them out, and based on this discovery, he completed a major invention.

The internal phase substance applied to the present invention is not particularly limited as long as it is substantially insoluble in water and liquid at room temperature, but it is thought to be particularly applicable to agricultural chemicals.

It is desirable for pesticides to be protected with polymers etc. until they are sprayed for safety and odor reasons, and the necessary amount of pesticides must be released on the plants after spraying. This is because it will not happen.

Pesticides include insecticides, fungicides, herbicides, attractants, pheromones, etc.If the pesticide is solid, it may be dissolved in water such as toluene or xylene, or it may be dissolved in liquid form. It can be dissolved in and used as an internal phase substance.

Of course, two or more types of agricultural chemicals may be mixed to form an internal compound.

The microcapsules used in the present invention are produced by a phase separation method from a water bath solution, preferably by a complex core cell process using gelatin as a cationic polymer.

Polyanions that can be used to form gelatin and coacervate include gum arabic, carrageenano, carboquine methyl cellulose, maleic acid copolymer, sodium boroacrylate, hexameta 1-ho/G fusoda, etc. For example, US P 2,8 D
O,457, US F 2,800.458B P
I, 117.178 specifications or Japanese Patent Publication No. 48-+
The microcapsules of the invention can be manufactured according to the known method disclosed in Publication No. 7985 and the like.

The present invention (deokero microcapsules) has the property of releasing internal phase substances when drying, and is an agglomerated polynuclear type microcapsule, and 2) has an average particle size of 20 to 100 μm, particularly preferably 60 to 70 μm. Maf Chrono Nobucell Al.

Mononuclear type microcapsules release internal phase substances when drying.
There is no characteristic of In addition, even among agglomerated polynuclear type microcapsules, those with an average particle size of less than 20 μm and those with an average particle size of 10
Particles with an average diameter of more than 10 μm have a weak property of releasing internal phase substances by squeezing them out during drying.Particles with an average particle size of 10 μm or less and particles with an average particle size of 150 μm or more have almost no property of releasing.

In the present invention, the agglomerated polynuclear type microcapsules can be produced by dispersing oil as an internal phase substance to a particle size of 2 to 19 μm and appropriately selecting encapsulation conditions such as pH and temperature. If the initial diameter of the dispersed oil is small, the diameter of the agglomerated multinucleated microcapsules produced also tends to be small.

Crosslinking of the membrane is carried out using commonly known formaldehyde or glutaraldehyde.

Microcapsules produced by a phase separation method from an aqueous solution are in a state in which the produced microcapsules are suspended in water, and the following can be added to this as necessary.

■Surfactants and spreading agents that lower the surface tension of the water layer and increase the amount of adhesion of aqueous suspensions.

■ Mizuura-ju polymer or polymer emulsion as a fixing agent to prevent microcapsules from falling off from the light surface of an object due to rain or wind; ■ To prevent agglomeration of microcapsules and increase dispersibility. Dispersants such as low molecular weight polyacrylates and clays.

The present invention is a water-based microcapsule! Examples are given to further specifically explain the present invention, which is a suspension.

Example 1 A mixture of equal weights of 0,2-dimethyl-8-(1,2-dicarboethoxyethyl)-dithiophosphinate and 0.0-diimpropyl-8-benodyluthiophosphate was used as the internal phase and dispersed. The average particle size of the oil is 5" m,
Microcapsules of agglomerated multinucleated u having an average particle size of 50 μm were produced by a method similar to Example 1 of Japanese Patent Publication No. 48-17985.

The amount of membrane material was 9 percent by weight of the internal phase, and the concentration of the internal phase in the aqueous suspension was 10 percent by weight. Dilute with 7U (so that the concentration of internal phase becomes 75N percent)
After stirring uniformly, a small amount of the aqueous suspension was spread on a glass plate and air-dried overnight. The amount of the internal phase substance sprinkled on the glass plate was determined from the increase in Xi, and the glass plate after drying was extracted with cyclohexano, and analyzed by gas chromatography.
The amount of internal phase material outside the microcapsules was quantified.

When coexisting, the solubility in water at room temperature is 90 ppm for 0.0-dimethyl-8-(1,2-dicarboethoxy/ethyl)-dithiophosphate.

Assuming 300 ppm for 0.0-diimpropyl-8-benzyl-thiophosphate, the weight of the internal phase outside the microcapsules determined by the cycloxane extraction method is 1. In this case, the former was about 45, and the latter was about 11.

Example 2 After cyclohexane extraction in Example 1, the glass plate was sprayed with mist and then left to stand overnight to elute the internal phase substances. The amount of water attached to the microcapsules 52η adhering to the glass plate was 460η.

This was extracted with cyclohexane in the same manner as in Example 1, and the amount of internal phase substances on the outside was quantified. The internal phase substance 1 on the outside of the microcapsules obtained by the cyclohexane extraction method is
If the amount determined from the solubility in attached water is set to 1, then 0
For 1O-dimethyl-5-(1,2-dicarboethoxy/ethyl)-dithiophosphate it was about 49; for 0,0-diinpropyl-8-benzyl-thiophosphate it was about 8.

Comparative Example 1 Mononuclear type microcapsules with an average particle size of 75 μm were manufactured using the L internal phase substance and capsule manufacturing method. The material of the membrane material is 16M1% of the internal phase. After diluting with water so that the concentration of the internal phase becomes 75% by volume, the outside is extracted by 7 black hegizano extraction in the same manner as in Example 1. The tl of the phase was quantified.

The amount of the internal phase substance outside the microcapsules determined by the cyclohexane extraction method is 0,0-dimethyl-8-(1,2-dicarboethoxyethyl)- For dithiophosphate it is about 6.0.
It was about 07 for 0-diisopropyl=S-benodyluthiophosphate.

patent applicant Takuya Gosei Chemical Industry Co., Ltd.

Claims (1)

[Claims] 1. Microcapsules are suspended in an aqueous medium,
The microcapsules are characterized by having an average particle diameter of 20 to 100 μm in an agglomerated polynuclear type consisting of an internal phase material that is substantially insoluble in water and liquid at room temperature and a membrane material mainly composed of gelatin.j7) Drying An aqueous suspension containing microcapsules that sometimes release internal substances.