JPH06287310A - Preparation of suspension of fine particles of composite resin material dispersed in nonaqueous solvent - Google Patents

Abstract

PURPOSE:To provide a process for preparing a suspension of fine particles of a composite resin material comprising a resin as the matrix and dispersed in a nonaq. solvent. CONSTITUTION:A process for preparing a suspension of fine particles of a composite material comprising a resin as the matrix and dispersed in a nonaq. solvent comprises dissolving or suspending the constituent materials of the composite material in a first nonaq. solvent as the good solvent for the resin, cooling the resulting suspension to solidify the first solvent, subliming the first solvent to remove it, mixing the residue with a second nonaq. solvent as the poor solvent for the resin, and pulverizing the above-mentioned residue in the solvent to convert it into fine particles.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a resin composite fine particle-dispersed non-aqueous solvent suspension having a filler or coloring material resin as a matrix.

[0002]

2. Description of the Related Art Conventional methods for producing resin composite fine particles using a resin as a matrix include a hot melt kneading and pulverizing method, a resin reprecipitation method, and a polymerization method.

[0003]

In the hot-melt kneading and pulverizing method, a resin to be a matrix is heated and melted, and a coloring material such as a pigment or a dye, which is a constituent material of a composite material, and / or a function for imparting the function to the resin are provided therein. After adding additives and thoroughly kneading, cooling, solidifying, and pulverizing at room temperature. When this method is used, the constituent materials such as colorants and additives are likely to be dispersed unevenly. Further, it is difficult to form fine particles by dry pulverization of such a hot melt kneaded product, and it is extremely difficult to obtain particles having a particle size of 10 μm or less, and further, a part of the resin is fused due to a local temperature rise during pulverization. There is a drawback of.

As a method for improving this, there is a freeze pulverization method. According to this method, the material to be ground (ground material) is frozen and embrittled by liquid nitrogen or the like before or during the grinding, but the cost tends to increase, and the particle diameter is 10 μm or less. Getting things is not easy. In addition, many of the fine particles obtained in the gas phase are flocculated, and considerable effort is required to uniformly disperse them in the non-aqueous solvent.

Further, as another improved method, there is an in-liquid pulverization method. In this method, a material to be ground (ground material) is suspended in a liquid and ground, and a local temperature rise can be prevented, but the particle size is almost the same as the above method.

The resin reprecipitation method utilizes the solubility of the resin in a solvent. The resin is dissolved in a first non-aqueous solvent in which the resin is soluble, and the other constituent materials of the composite material are dissolved in this resin. The second non-aqueous solvent, which is a poor solvent for the resin, is prepared by suspending or dissolving in the solvent of No. 1 and cooling the solvent using the suspended or dissolved constituent material as a nucleus. Is added to the solvent to precipitate the resin to produce composite fine particles having the resin as a matrix. However, this method is limited in the proper combination of the resin and the non-aqueous solvent with respect to solubility. Therefore, the non-aqueous solvent cannot be arbitrarily selected. Further, it is necessary to devise a considerable measure to make the particle diameter of the generated fine particles 10 μm or less, and the resin particles precipitated in the solvent containing the good solvent with respect to the resin are easily aggregated and difficult to be dispersion stable fine particles.

In the polymerization method, a monomer, which is a raw material of a resin serving as a matrix, is suspended or dissolved in a non-aqueous solvent together with the constituent materials of the composite material, and the monomer is polymerized while wrapping these constituent materials to produce fine composite particles. However, it is difficult to control the polymerization conditions, and it is inevitable that impurities such as a dispersant, a surfactant, and a polymerization initiator used at the time of polymerization adhere to the generated particles, and various functions are added. It is essential to remove impurities on the surface of particles for purification, but it is difficult to purify as the particles become finer.

In view of the above-mentioned state of the art, the present invention aims to provide a method for producing resin composite fine particles in a non-aqueous solvent, which does not have the problems of the conventional method.

[0009]

The present invention provides a method for producing a non-aqueous solvent suspension in which fine particles of a composite material having a resin as a matrix are dispersed, wherein a constituent material of the composite material is a good solvent for the resin. Is dissolved or suspended in the first non-aqueous solvent, which is then cooled to solidify the first solvent, and then the first non-aqueous solvent is sublimated and removed, and the residue is applied to the resin. On the other hand, the method is a method for producing a resin composite fine particle-dispersed non-aqueous solvent suspension, which comprises mixing with a second non-aqueous solvent, which is a poor solvent, and then pulverizing it in a liquid to form fine particles.

Furthermore, the present invention will be described more specifically as follows.
The present invention relates to a method for producing a non-aqueous solvent suspension in which resin composite fine particles having a resin matrix are dispersed,
The resin of the first non-aqueous solvent, which is a good solvent, is dissolved in the resin to be the matrix, and constituent materials other than the resin, such as the pigment of the composite material, are dissolved or suspended in the solvent and sufficiently mixed. To form a homogeneous solution or suspension, then use a cryogen such as liquid nitrogen to rapidly solidify the solution or suspension at a low temperature, and then use a vacuum device to sublimate only the solvent. To obtain a solid residue having a porous or fibrous friable shape consisting of only the constituent materials of the resin composite material, and mixing this with a second non-aqueous solvent which is a poor solvent for the resin. It is a method of producing a resin composite fine particle-dispersed non-aqueous solvent suspension having a particle diameter of 10 μm or less and excellent in dispersibility by pulverizing in a liquid using a wet pulverizer such as a bead mill.

The resin used in the present invention is an olefin resin having a carboxyl group or an ester group, and is applicable to the first non-aqueous solvent, for example, an aromatic system such as toluene or a ketone system such as methyl ethyl ketone. A solvent that is soluble and is sparingly soluble in the second non-aqueous solvent, for example, a straight chain or branched chain aliphatic hydrocarbon or a halogenated aliphatic hydrocarbon is preferable. For example, ethylene vinyl acetate copolymer, (meth) acrylic resin, styrene (meth) acrylic acid copolymer, ethylene (meth) acrylic acid copolymer, partially saponified ethylene vinyl acetate copolymer, ethylene (meth) acrylic Examples thereof include acid ester copolymers, styrene (meth) acrylic acid ester copolymers, polyesters, and the like. One of these may be used, or two or more of them may be mixed and used.

A dispersant may be added if necessary. This dispersant is preferably soluble in both the first non-aqueous solvent and the second non-aqueous solvent, and examples thereof include nonionic compounds such as sorbitan fatty acid ester.

[0013]

When the resin itself forming the matrix is heated and melted and the constituent materials of the composite material are kneaded therein, as in the above-mentioned hot melt kneading and pulverizing method, the mixing medium has a very high viscosity. Therefore, it is difficult to uniformly disperse the constituent materials such as pigments, whereas in the present invention, a good solvent for the resin having a low viscosity, such as toluene, is used to dissolve or suspend the matrix resin and constituent materials. Since it becomes turbid, mixing and dispersion can be facilitated and homogeneous dispersion can be achieved.

In the resin reprecipitation method, since the precipitation operation is carried out in a liquid, the resin to be precipitated or the constituent materials contained therein are liable to move, so-called segregation is likely to occur, and the quality of the precipitated fine particles is heterogeneous. On the other hand, in the present invention, a cryogen such as liquid nitrogen is used in the present invention to freeze and solidify the constituent materials to fix the constituent materials in a uniformly dispersed state, and then the solvent (first non-aqueous solvent) is sublimated and removed. Therefore, when removing the solvent, there is no movement of these constituent materials,
A solid residue in which these constituent materials are homogeneously dispersed is obtained. Further, in the resin reprecipitation method, considerable measures are required to prevent the deposited particles from swelling due to a good solvent in the deposition solvent and causing fusion and coarsening between the particles. On the other hand, according to the present invention, the solvent (first non-aqueous solvent) is sublimated and removed, so that the shape of the solid residue is rich in voids and is fibrous or so-called pumice-like that is generated by volcanic eruption or the like. The product is very easy to crush.

Further, as described above, since the solid residue becomes pumiceous, the surface area per unit weight becomes large and the residual amount of the solvent (first non-aqueous solvent) becomes small in the solvent sublimation removal operation. Even at that time, the sublimation rate of the solvent is not deteriorated, and the amount of the residual solvent (first non-aqueous solvent) is extremely small. By mixing the solid residue thus obtained with a desired poor solvent (second non-aqueous solvent) and pulverizing in a liquid using a wet pulverizer such as a bead mill, a local temperature rise is caused. The fusion and coarsening of the resin fine particles are suppressed, and the fusion and coarsening of the resin fine particles due to the partial compatibility between the good solvent (first non-aqueous solvent) and the resin do not occur.

Thus, according to the invention, the particle size is 10 μm.
It has become possible to form the following resin composite fine particles having good dispersion stability in a non-aqueous solvent. In addition, in order to improve dispersion stability, the above-mentioned dispersant may be added in advance or at the time of pulverizing in liquid.

[0017]

【Example】

(Example 1) Styrene methacrylic acid ester resin (Hayma LTB500 manufactured by Sanyo Kasei Co., Ltd.) as a resin: 3 parts, carbon black (Diablack MA7 manufactured by Mitsubishi Kasei Co., Ltd.) as a pigment: 1 part, sorbitan fatty acid ester (Katayama Chemical Co., Ltd.) as a dispersant SPAN85) manufactured by the same company: 0.1 parts and benzene: 7 parts as the first non-aqueous solvent were sufficiently kneaded with a bead mill to disperse carbon black, and 263 parts of benzene were further added and sufficiently stirred to homogenize. Then, the whole amount was solidified by quenching with a cooling medium cooled to −50 ° C. by a cooler.

Next, the pressure was reduced to 0.5 torr using a vacuum device, and only benzene was sublimated and removed to obtain a solid residue.

To this solid residue, 36 parts of isoparaffinic hydrocarbon (Isopar G manufactured by Esso Oil Co., Ltd.) as a second non-aqueous solvent was added, and the solid residue was crushed using a bead mill to obtain a pigment having the above resin as a matrix. Particle diameter (median diameter) in which a certain carbon black is uniformly dispersed.
A non-aqueous solvent suspension in which 064 μm resin composite fine particles were stably dispersed was obtained.

The particle size distribution of the resin fine particles obtained in this Example 1 is shown in FIG. In FIG. 1, the vertical axis on the right side is the cumulative% of particles and corresponds to the curve in the figure, and the vertical axis on the left side is the frequency% at each particle size and corresponds to the bar graph in the figure. The median diameter is the average particle diameter, and the specific surface area is the surface area of particles per cm ³ . Particle diameter%: 5.00 μm = 89.7% is 5.
89.7% of particles with a size of 00 μm or more are used.
Particle diameter: 90.0% = 3.919 μm is 3.919 μm
The above particles represent 90%.

(Example 2) The same formulation as in Example 1 was carried out except that an organic pigment (Red # 5 manufactured by Dainichiseika Co., Ltd.) was used in place of carbon black as the pigment, and the resin was used as a matrix. A non-aqueous solvent suspension was obtained in which the resin composite fine particles having a particle diameter (median diameter) of 6.535 μm in which the pigment was uniformly dispersed were stably dispersed. The particle size distribution of the resin fine particles obtained in this Example 2 is shown in FIG. FIG. 2 has the same meaning as FIG.

[0022]

According to the present invention, an olefin resin having a carboxyl group or an ester group is used as a matrix, and a composite constituent material such as a pigment is uniformly dispersed in the matrix.
It is possible to produce a non-aqueous solvent suspension using an aliphatic hydrocarbon or the like in which resin composite fine particles having a size of μm or less are stably dispersed. Further, according to the present invention, since resin composite fine particles dispersed in a non-aqueous solvent can be obtained, it is easy to newly disperse the generated fine particles in a vehicle of an ink or paint or in an organic solvent. It can be effective.

[Brief description of drawings]

FIG. 1 is a particle size distribution chart of resin composite fine particles obtained in Example 1 of the present invention.

FIG. 2 is a particle size distribution chart of resin composite fine particles obtained in Example 2 of the present invention.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Mitsuharu Murakami 4-6-22 Kannon Shinmachi, Nishi-ku, Hiroshima City, Hiroshima Prefecture Mitsubishi Heavy Industries Ltd. Hiroshima Research Laboratory

Claims (1)

[Claims] 1. A method for producing a non-aqueous solvent suspension in which fine particles of a composite material having a resin as a matrix are dispersed, wherein the constituent material of the composite material is a good non-solvent for the resin. After dissolving or suspending in a solvent and then cooling to solidify the first solvent, the first non-aqueous solvent is sublimated and removed, and the residue is a poor solvent for the resin. A method for producing a resin composite fine particle-dispersed non-aqueous solvent suspension, which comprises mixing with the non-aqueous solvent of No. 2 and then pulverizing in a liquid to form fine particles.