JPH0681771B2 - Method for producing porous crosslinked polyester particles - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing porous crosslinked polyester particles. The porous crosslinked polyester particles of the present invention are useful, for example, as a coating component, a carrier for sustained release, a carrier for immobilizing enzymes and microorganisms, an additive for plastics, and the like.

In the following description, "part" and "%" are all based on weight.

Conventional Technology and Its Problems Conventionally, as a method for producing porous crosslinked polyester particles, an organic phase emulsifier is added to an oil phase composed of an unsaturated polyester and a vinyl monomer capable of being crosslinked therewith, and an oil is added to the oil phase. A method is known in which a water-in-water emulsion is prepared, and the emulsion is redispersed in water and then crosslinked and cured as it is. As organic organic emulsifiers used at this time, for example, water-soluble polyamines (Japanese Patent Publication No. 52-13829), surfactants (JP-A No. 48-90381) and the like have been proposed. However, the method using a water-soluble polyamine has a problem that the obtained porous crosslinked polyester particles are colored. In the method using a surfactant, the water vesicles in the water-in-oil emulsion particles become too large.
The resulting polyester particles are monocellular, and it is difficult to obtain porous particles. Further, it is not possible to obtain porous polyester particles having a particle size of 50 μm or less.

Means for Solving the Problems As a result of intensive studies in view of the problems of the above-mentioned conventional techniques, the present inventor has found that when producing a water-in-oil emulsion, an oxide of an alkaline earth metal and / or When a hydroxide is used, it is possible to produce porous cross-linked polyester particles that have very little coloring (extremely high whiteness) and have many vesicles, and the particle size of the resulting polyester particles can be adjusted freely. The present invention has been completed by finding that porous crosslinked polyester particles having a diameter of 50 μm or less can be easily produced and the diameter of vesicles in the produced polyester particles can be freely adjusted.

That is, according to the present invention, an aqueous suspension of an oxide and / or hydroxide of an alkaline earth metal is dispersed in an oil phase composed of an unsaturated polyester and a vinyl-based monomer capable of cross-linking the unsaturated polyester. The present invention relates to a method for producing porous crosslinked polyester particles, which comprises a first step of producing an aqueous emulsion, and a second step of redispersing the emulsion in an aqueous solution of a suspension stabilizer and crosslinking and curing the emulsion.

In the present invention, the reason why porous cross-linked polyester particles having no coloring and a large number of vesicles can be obtained by utilizing an oxide and / or hydroxide of an alkaline earth metal is not yet clear, It is likely due to some chemical reaction between the unsaturated polyester and the alkaline earth metal salt.

The method of the present invention includes a first step and a second step.

In the first step, an unsaturated polyester and a vinyl-based monomer capable of crosslinking the polyester (hereinafter simply referred to as “vinyl-based monomer”) are mixed to form an oil phase.

The unsaturated polyester is not particularly limited, for example,
Examples thereof include those obtained by polycondensing an α, β-unsaturated acid or a mixture of the same with a saturated acid and a dihydric alcohol or a trihydric alcohol. Examples of unsaturated acids include fumaric acid, maleic acid and itaconic acid, and examples of saturated acids include phthalic acid, terephthalic acid, succinic acid, glutaric acid, tetrahydrophthalic acid, adipic acid and sebacic acid. Examples of dihydric alcohols and trihydric alcohols include ethylene glycol, diethylene glycol, propylene glycol, neopentyl glycol, 1,3-propanediol, 1,6-hexanediol and trimethylolpropane.
The acid value of the unsaturated polyester is not particularly limited, but the stability of the water-in-oil emulsion (hardness to break), especially the stability of the water-in-oil emulsion when producing porous polyester particles having a particle size of 50 μm or less Considering that, 5-30mgKOH /
It is preferred to use unsaturated polyesters having an acid number of the order of g.

The vinyl monomer is not particularly limited, and examples thereof include styrene, chlorostyrene, vinyltoluene, divinylbenzene, acrylic acid, methyl acrylate, acrylonitrile, ethyl acrylate and diallyl phthalate.

The blending ratio of the unsaturated polyester and the vinyl-based monomer is not particularly limited, but usually 50 to 200 parts of the vinyl-based monomer may be blended with 100 parts of the unsaturated polyester.

Then, to the oil phase obtained above, an aqueous suspension of an alkaline earth metal oxide and / or hydroxide (hereinafter simply referred to as “alkaline earth metal salt”), which is an emulsifier, is added and dispersed to obtain an oil. A medium water type emulsion is produced.

The alkaline earth metal salt is not particularly limited, and for example,
Examples thereof include magnesium oxide, calcium oxide, barium oxide, strontium oxide, magnesium hydroxide, calcium hydroxide, barium hydroxide and strontium hydroxide. Although the amount of the alkaline earth metal salt used is not particularly limited, it is usually about 0.01 to 20 parts, preferably about 0.1 to 5 parts, relative to 100 parts of the oil phase. The amount of water used to suspend the alkaline earth metal salt may be about 10 to 600 parts, preferably about 50 to 400 parts, relative to 100 parts of the oil phase. The method of suspending the alkali metal salt in water is not particularly limited, and may be sufficiently suspended using, for example, a ball mill or a high speed stirrer.

To add a water suspension of an alkaline earth metal salt to the oil phase to form a water-in-oil emulsion, a general method such as stirring can be adopted. For example, an aqueous suspension of an alkaline earth metal salt may be gradually added to the oil phase and vigorously stirred with a disper mill, a colloid mill or the like. The stirring speed is not particularly limited, but the peripheral speed of the stirring blade is usually about 10 to 60 m / sec, preferably about 15 to 30 m / sec.

In the second step, the water-in-oil emulsion obtained above is redispersed in an aqueous solution of a suspension stabilizer.

As the suspension stabilizer, for example, polyvinyl alcohol,
Partially saponified polyvinyl alcohol, hydroxymethyl cellulose, hydroxyethyl cellulose and the like can be mentioned. The suspension stabilizers can be used alone or as a mixture of two or more kinds. The concentration of the suspension stabilizer in the aqueous solution may be appropriately selected according to the particle diameter of the porous polyester resin particles to be obtained, etc., but is usually about 0.1 to 10%.

The stirring speed at the time of redispersing the water-in-oil emulsion in the aqueous solution of the suspension stabilizer may be appropriately selected according to the particle diameter of the porous crosslinked polyester particles to be obtained. Generally, when stirring is fast, particles having a small particle size are obtained, and when stirring is slow, particles having a large particle size are obtained. For example, if the peripheral speed of the stirring blade is about 1 to 15 m / sec, 3 mm to 0.5 μm
Some particles are obtained.

Next, the water-in-oil emulsion in the redispersion is crosslinked and cured. The cross-linking curing is performed by a usual method. For example, a polymerization initiator may be added to the redispersion while stirring to crosslink and cure it. As the polymerization initiator, those used as a polymerization initiator for the unsaturated polyester resin can be used. Specifically, for example, organic peroxides such as benzoyl peroxide, methyl ethyl ketone peroxide, cumene peroxide and t-butyl peroxide, inorganic peroxides such as ammonium persulfate, sodium persulfate and potassium persulfate, and methyl ethyl ketone peroxide. Examples thereof include redox polymerization initiators such as oxide-cobalt organic acid salts and cumene hydroperoxide-cobalt organic acid salts. The polymerization initiator may be added in advance to the oil phase obtained in the first step. In addition, in the redox-based polymerization initiator composed of two components, one component may be added to the oil phase in the first step and the other component may be added to the redispersion. Although the amount of the polymerization initiator used is not particularly limited, it is usually 0.5 to 5 parts with respect to 100 parts of the oil phase. The polymerization temperature is not particularly limited, but is usually about 10 to 40 ° C. The stirring speed is not particularly limited, but the peripheral speed of the stirring blade is usually about 1 to 10 m / sec.

As a result, a slurry of porous crosslinked polyester particles having very little coloring, a large number of vesicles having a pore size of about 0.2 to 2 μm, and a particle size of usually about 0.5 μm to 3 mm can be obtained. The slurry can be used as it is as a component for paint.

In the present invention, the slurry of the porous crosslinked polyester particles may be dried if necessary. As a result, porous crosslinked polyester particles having excellent mechanical strength and occlusion property can be obtained. Drying is usually performed at about 80 to 120 ° C. according to a conventional method.

Effects of the Invention According to the present invention, the following excellent effects are achieved.

(1) According to the present invention, porous crosslinked polyester particles having very little coloring (extremely high whiteness) and having many vesicles can be produced, and the particle size of the produced polyester particles can be freely controlled. Porous crosslinked polyester particles having a diameter of 50 μm or less can be easily produced, and the diameter of the vesicles in the produced polyester particles can be freely adjusted.

(2) By adding the slurry of the porous crosslinked polyester particles of the present invention to a water-soluble resin, an emulsion resin, a water-based adhesive, etc., a lightweight coating film with high hiding property can be formed.

(3) The porous crosslinked polyester particles of the present invention have high mechanical strength and are excellent in occluding various components such as fragrances, agricultural chemicals, pigments, dyes, catalysts, etc., and even 60% or more of the particle weight. Can occlude. For example, when the fragrance is occluded in the vesicles, a sustained release form of the fragrance can be obtained. Further, by impregnating the particles with a lubricating oil agent and kneading the particles into a plastic, an oil-containing plastic excellent in lubricity and mechanical strength can be obtained. In addition, if pesticides such as insecticides, pheromones, insect hormones, acaricides, pesticides, fungicides, herbicides, plant growth regulators, rodenticides, etc. are allowed to be occluded, it becomes possible to control their release and occlude pesticides. The polyester particles may be mixed with various plastics, molded with an adhesive, or applied to a support such as paper, plastic, or wood, or further coated with various plastic films or paints. If this is the case, the release of pesticides can be controlled more precisely.

(4) By adding various components such as fragrances and agricultural chemicals to an aqueous suspension of alkaline earth metal, it is possible to produce a slurry of porous crosslinked polyester particles in which the above components are occluded in advance. The slurry can be easily mixed as it is with a water-soluble resin, an emulsion resin, an aqueous adhesive or the like, and for example, a sustained-release coating film or adhesive layer of perfume, agricultural chemicals or the like can be easily obtained.

(5) By adding an enzyme, a microorganism, or the like to an aqueous suspension of an alkaline earth metal, it is possible to produce immobilized porous crosslinked polyester particles without deteriorating the activity of the substance.

EXAMPLES Next, the present invention will be described more specifically with reference to Examples and Comparative Examples.

Example 1 70 parts of unsaturated polyester [trade name: Epolak N-14B, acid value 12, styrene content 30%, manufactured by Nippon Shokubai Co., Ltd.]
30 parts of styrene and 0.5 part of cobalt naphthenate (cobalt content: 6%) are stirred with a Dispa type stirrer at a peripheral speed of 20 m / sec, while strontium hydroxide [reagent, manufactured by Mitsuwa Chemical Co., Ltd.] 1 part To 200 parts of water was gradually added a water suspension dispersed in a ball mill for 5 hours to obtain a water-in-oil emulsion. Then, the emulsion was prepared by preparing polyvinyl alcohol [polymerization degree 2000, saponification degree 80
%, Manufactured by Wako Pure Chemical Industries, Ltd.] 160 parts of 3.5% aqueous solution and hydroxyethyl cellulose (trade name: Natrosol 250-H
HR, manufactured by Hercules Co., Ltd.), and mixed with 90 parts of a 2% aqueous solution, and continued to be stirred with a propeller-type stirrer at a peripheral speed of 5 m / sec for 10 minutes, and further methyl ethyl ketone peroxide (trade name: Kayamek A, 55% pure) Manufactured by Kayaku Akzo Co., Ltd.]
When 3 parts was added and stirring was continued for 2 hours at 30 ° C. and a peripheral speed of 2 m / sec, a slurry of white porous crosslinked polyester particles in which the unsaturated polyester layer was crosslinked and hardened was obtained.
The cake obtained by washing and filtering the polyester particles is 110
It dried at 1 degreeC for 1 hour, and obtained the fine powder.

Examples 2-3 In the same manner as in Example 1 except that 1 part of calcium hydroxide (Example 2) or 1 part of magnesium oxide (Example 3) is used instead of 1 part of strontium hydroxide. As a result, fine powder was obtained.

Comparative Examples 1-2 In Example 1, except that 1 part of sorbitan monooleate of HLB1.8 (Comparative Example 1) or diethylenetriamine (Comparative Example 2) was used in place of 1 part of strontium hydroxide, The same operation was performed. In Comparative Example 1, no water-in-oil emulsion was formed. In Comparative Example 2, fine powder was obtained.

Example 4 In Example 1, 160 parts of 3.5% aqueous solution of polyvinyl alcohol and 2% aqueous solution of hydroxyethyl cellulose 90
60 parts of a 5% aqueous solution of polyvinyl alcohol and a 2% aqueous solution of hydroxyethyl cellulose instead of the mixture with 19 parts
A fine powder was obtained in the same manner as in Example 1 except that a mixture with 0 part was used.

Example 5 In Example 1, the unsaturated polyester (Epolak N
-14B) in place of another type of unsaturated polyester [Product name:
Epolak G-110AL, acid value 24, styrene content: 30%,
Nihon Shokubai Co., Ltd.] is used, and 160 parts of a 3.5% aqueous solution of polyvinyl alcohol and 2 parts of hydroxyethyl cellulose are used.
A fine powder was obtained in the same manner as in Example 1 except that 250 parts of a 1.5% aqueous solution of polyvinyl alcohol was used instead of the mixture with 90 parts of a% aqueous solution.

Comparative Example 3 A fine powder was obtained in the same manner as in Example 5 except that 3 parts of sorbitan monooleate of HLB1.8 was used instead of 1 part of strontium hydroxide.

With respect to the fine powders obtained in Examples 1 to 5 and Comparative Examples 1 to 3, the whiteness, the particle size, and the cross-sectional structure of the powder particles were examined. The whiteness was measured with a Kett photoelectric whiteness meter. The particle size and the cross-sectional structure of the particles were examined by a scanning electron microscope. The results are shown in Table 1 below and FIGS. First to
FIG. 5 is a micrograph showing the cross-sectional structure of the particles obtained in Examples 1 to 5, and FIGS. 6 and 7 are Comparative Example 2 respectively.
3 is a micrograph showing a cross-sectional structure of the particles obtained in and.

It can be seen from Table 1 and FIGS. 1 to 7 that the porous crosslinked polyester particles of the present invention have a high whiteness and a large number of vesicles having a substantially uniform diameter as compared with the conventional ones. I understand.

Example 6 In Example 1, instead of 200 parts of water for suspending strontium hydroxide, a sustained-release fragrance [trade name: BGM-584
8. Takasago Fragrance Co., Ltd.] 90 parts of polyoxyethylene hydrogenated castor oil [Product name: Emanone CH40, Kao Co., Ltd.] 10
% Particle size 1 to 15 in the same manner as in Example 1 except that a fragrance / oil-in-water emulsion emulsified in 110 parts by weight of aqueous solution is used.
A slurry of fragrance-containing polyester particles of μm was obtained.

40 parts of this slurry was mixed with 100 parts of emulsion resin [trade name: Boncoat 6290, solid content 50%, manufactured by Dainippon Ink and Chemicals, Inc.] to obtain a paint. The coating film obtained by applying this coating material to a slate plate had sufficient aromaticity even after one month.

Example 7 and Comparative Example 4 The slurry of the porous crosslinked polyester particles obtained in Example 1 was used to prepare an emulsion paint having a blending ratio (parts by weight) shown in Table 2 below, and the concealing property of the dried coating film was prepared. Was examined (Example 7).

For comparison, a coating material was prepared in the same manner as above except that the slurry was not used, and the hiding property of the dried coating film was examined (Comparative Example 4).

From Table 2, it is clear that the slurry of the porous crosslinked polyester particles of the present invention imparts excellent concealing property to the dry coating film.

[Brief description of drawings]

1 to 7 are photomicrographs showing the cross-sectional structures of the crosslinked polyester particles obtained in Examples 1 to 5 and Comparative Examples 2 and 3, respectively.

Claims (1)

[Claims] 1. A suspension of an alkaline earth metal oxide and / or hydroxide in water is dispersed in an oil phase composed of an unsaturated polyester and a vinyl monomer capable of cross-linking the unsaturated polyester. A method for producing porous crosslinked polyester particles, comprising a first step of obtaining an aqueous emulsion, and a second step of redispersing the emulsion in an aqueous solution of a suspension stabilizer to crosslink and cure it.