JPH028230A - Resin particle and production thereof - Google Patents

Abstract

PURPOSE:To provide a resin particle composed mainly of an ethylene-vinyl alcohol copolymer, formed in porous form and having useful characteristics and excellent workability in production and use. CONSTITUTION:The objective resin particle is composed mainly of an ethylene- vinyl alcohol copolymer and formed in porous form. The particle has a diameter of <=2mm and essentially spherical shape. It can be produced by dissolving a resin composed mainly of the above copolymer in a solvent, precipitating the resin particles by mixing with a poor solvent or by decreasing the temperature and drying the precipitated particles. Preferably, the ethylene-vinyl alcohol copolymer has an ethylene content of 20-60mol% and a saponification degree of vinyl acetate of >=80%.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to resin particles, and more specifically to materials for powder coatings, foam molding, sintering molds, etc., polymer modifiers, resin molded products, and The object of the present invention is to easily provide resin particles that are useful as a matting agent for paints, etc., and as an additive for cosmetics, toners, etc., have excellent workability during production and use, and have characteristics not found in the past.

(Prior Art and its Problems) Various resin particles have been produced in large quantities by various methods and used for many purposes.

Among conventional resin particles, attempts have been made to pulverize ethylene-vinyl alcohol copolymer (hereinafter referred to as EVOH) or polyamide resin (hereinafter referred to as PA), but especially for EVOH, solid EVOH is mechanically pulverized. method has been used.

However, because EVOH is a strong polymer, it takes a lot of energy and a long time to mechanically crush it, and one of the characteristics of mechanical crushing is that it is difficult to obtain powder with a uniform and fine particle size. The disadvantage was that it was difficult.

Further, resin particles are required to be porous and spherical depending on their use, but it has been difficult to obtain porous and spherical fine particles using the mechanical pulverization method described above.

Therefore, it has been difficult to develop applications for resin particles that take advantage of EVOH's characteristics such as toughness, oil and organic solvent resistance, weather resistance, and water absorption.

Therefore, the present invention provides EVs having fine, uniform particle size and porous structure.
To provide OH resin particles at low cost and stably in mass production.

(Means for Solving the Problems) The present inventor completed the present invention as a result of intensive research to meet the demands of the prior art as described above.

That is, the present invention involves dissolving porous resin particles containing EVOH as a main component and resin containing EVOH as a main component in a solvent, and precipitating the resin particles by mixing with a poor solvent or lowering the temperature. This is a method for producing porous resin particles characterized by drying.

(Function) A resin whose main component is EVOH is dissolved in a solvent, and by mixing with a poor solvent or by lowering the temperature, resin particles are precipitated and then dried. Porous resin particles are easily made into fine and uniform particle sizes. can be provided to

(Preferred Practical hh Embodiments) Next, the present invention will be described in more detail by citing preferred embodiments.

The EVOH used in the present invention is an oxide of an ethylene-vinyl acetate copolymer, and a particularly preferred one has an ethylene content of 20 to 60 mol% and a saponification degree of the remaining vinyl acetate units of 80. % or more, preferably 90% or more.

In the present invention, when the EVOH is powdered, the EVOH
OH may be used alone, or PA may be mixed therein to form a mixture of resin particles.

A preferable PA of this kind is an amide bond (-
It is a synthetic linear PA whose main chain is composed of repeating (:0NI-1-), such as ring-opening polymer of caprolactam, nylon 6 produced by condensation polymerization of 6-aminocaproic acid,
Nylon 66 and nylon 6 produced by condensation polymerization of hexamethylene diamine and dicarboxylic acids such as adipic acid and sebacic acid.
10. Nylon 11 with 11-aminoundecanoic acid,
Other examples include homopolymers and copolymers of nylon 12. Since such PA has excellent self-lubricity, it is preferable because the PJ friction coefficient of the obtained powder is reduced and the fluidity etc. of the powder state are improved in actual application.

The amount of PA to be mixed is approximately 1 to 5 per 00 parts by weight of EVOHl.
A range of 0 parts by weight is preferable; if the mixing amount is less than the above range, the effect of mixing will be insufficient, and if it exceeds the above range, it will be difficult to powderize due to the self-fusing properties of PA, which is not preferable. .

The resin particles of the present invention can be obtained by dissolving the above-mentioned EVOH or a mixture of EVOH and PA in a suitable solvent, precipitating the resin particles by mixing with a poor solvent or lowering the temperature, and then drying.

Solvents for dissolving EVOH or its mixture with PA include methanol, ethanol, n-propanol, isopropanol, butanol, hensyl alcohol, N
, N-dimethylformamide, dimethyl sulfoxide, etc., or mixtures thereof. Examples of solvents that can be mixed with these solvents to promote the solubility of the resin or stabilize the solution include water, ethylene glycol, propylene glycol, glycerin, Poor solvents such as toluene and xylene, CaC
Alkaline earth metal halides or alkali metals such as 1□, LiCl, and NaCl can be used alone or in combination.

EVOH or a mixture of EVOH and PA may be dissolved by any conventionally known method such as a dissolving pot equipped with a stirrer, normal pressure, pressurized type, or heating type, and the concentration of the dissolved material is not particularly limited, but the concentration of the resulting resin particles Considering the controllability of the diameter, etc., the preferred concentration is 5 to 50fffffi%.

As a method for precipitating resin particles from the above solution, (a) a method in which a solution in which a resin is dissolved at a high temperature in a solvent that does not dissolve the resin at room temperature (30°C) is cooled to below room temperature, (b) a stable resin A method in which a poor solvent for the resin is added to the solution while stirring to precipitate resin particles; (c) a method in which the resin is dissolved at room temperature and liquid nitrogen is poured into the solution to cool it; or a method in which the resin is cooled from outside the container. method, (d) method of selectively evaporating (extracting) the solvent from the resin solution and precipitating it in a poor solvent, (e) method of introducing the resin solution into the poor solvent, (f) spray drying the resin solution. Examples include a method in which resin particles are precipitated by doing so. Preferred methods are methods (a) and (0), but any method can be used in the present invention.

The resin particles precipitated by the above method are porous,
It is important to separate the resin particles from the solvent while maintaining this porosity; drying at high temperatures will cause the resin particles to fuse together and lose their porosity; therefore, the solvent can be separated from the resin particles at a relatively low temperature. Preferably, it is removed. However, depending on the application, it can also be used as a dispersion of resin particles as it is without separating the solvent.

As a method for separating the solvent and resin particles, a method of concentrating and drying a dispersion of resin particles by a known method such as vacuum drying, freeze drying, centrifugation, or filtration is preferable.

Although resin particles of various particle sizes can be obtained by the above method,
The particle size of resin particles can be controlled by controlling the resin concentration of the solution, the precipitation method,
Factors such as concentration method and drying method act in a complex manner. One way to reduce the particle size is to lower the resin concentration in the solution and precipitate it under strong stirring, and then to prevent the precipitated resin particles from agglomerating or re-dissolving with a solvent at a low temperature and under strong stirring. It is desirable to remove the solvent and dry.

The resin particles of the present invention obtained in this way have a diameter of about 0.5 μm.
It has a particle size of 2 mm to 2 mm, preferably about 0.5 to 5 μm, microscopically it is a sponge-like porous particle, and the density is 0.15 to 0.3 g/crn. In some cases, the particles are spherical with uniform diameter.

In addition to PA, the resin calf of the present invention as described above may contain other resins, if necessary, within a range that does not impede achievement of the purpose of the present invention.
Any additives such as pigments, stabilizers, lubricants, surfactants, fiber powders, metal powders, etc. can be optionally mixed.

(Effects) According to the present invention as described above, a resin containing EVOH as a main component is dissolved in a solvent, resin particles are precipitated by mixing with a poor solvent or by lowering the temperature, and then dried to form a porous resin. Particles are easily provided with fine and uniform particle size.

These effects are because EVO)I or PA has many hydrogen bonds and has high crystallinity and cohesiveness, so it does not gel when precipitated from a solvent, but precipitates in a spherical and porous form, and when dried, It is also believed that these spherical shapes and porous properties can be maintained.

(Example) Next, the present invention will be described in more detail with reference to Examples. It should be noted that unless otherwise specified, the terms in the text or % are based on weight.

Fruit Overturning 1 20 parts of EVOH with an ethylene copolymerization ratio of 47 mol%, 60 parts of methanol, and 20 parts of water were placed in a dissolving vessel equipped with a stirrer, and stirred at 60° C. for 3 hours to obtain a transparent resin solution. Next, stirring was continued while cooling the melting pot. The solution gradually became cloudy and when cooled to 5° C., the resin particles were completely precipitated, yielding a cloudy dispersion of resin particles.

Distillation under reduced pressure was carried out while uniformly mixing the whole at 5°C. When the amount of solvent extracted from the resin liquid reached 56 parts, the temperature of the pot was raised to 60°C and drying was performed for 5 hours to obtain the present invention. of resin particles were obtained. The average particle size of this material is 1 μm and the specific gravity is 0.17 g/crn.
As is clear from the figure, the particles are porous and spherical with uniform particle size.

The above resin particles were mixed and dispersed as a matting agent at a ratio of 50 parts per 100 parts of acrylic paint, and this matting paint was applied to the surface of soft vinyl chloride leather. The resulting matte leather had an excellent matte feel compared to the same paint containing silica that has been used in the past, and the scratch resistance of the surface by fingernails and the like was significantly improved.

Example 2 EVOH with an ethylene copolymerization ratio of 44 mol% (melting point 164
°C) 7 parts and copolymerized nylon (trade name: Bratabond M1)
276 (melting point: 115°C) was stirred for 3 hours at a temperature of 80°C in a dissolving pot containing 60 parts of ethanol and 30 parts of water to completely dissolve the resin. Further, 2 parts of a titanium oxide pigment for paint was added to this solution (B) and uniformly dispersed.

Next, the temperature was lowered to 50° C., and while stirring was continued, 60 parts of a mixed solvent of ethanol/water (weight cost: 476 ml) was added little by little to the kettle to precipitate the resin in the form of a colloid. This product was dried by a spray dry method at room temperature to obtain white resin particles.

Further, this product was transferred to a vacuum container equipped with a stirrer and dried under reduced pressure at 30°C, and the remaining solvent was extracted to obtain dry resin particles of the present invention. The average particle size of these resin particles is 5 μm and the specific gravity is 2 g/
It was c♂. This material was applied as a powder coating to a metal plate heated to 190°C by the fluidized dipping method to a thickness of 40 to 50 μm.
A white coating film with a thickness of . This coating film has gloss, physical properties,
It has excellent solvent resistance and is useful as a powder coating.

Furthermore, when these resin particles were classified and resin particles with an average particle size of 0.5 μm were taken out and applied to foundations,
In addition to the spherical and porous nature of the resin particles used, E
Due to the water-absorbing effects of VOH and PA, the feel was good and the makeup lasted well.

Example 3 30 parts of EVOH with an ethylene copolymerization ratio of 32 mol%, 10 parts of methanol, 30 parts of ethanol, and 20 parts of water were completely dissolved in the same manner as in Example 1 at 60° C. for 10 hours. The resin particles of the present invention were obtained using an instant mixer having a mixing tank with a capacity of 200 cc that can mix 100 parts of this solution with 100 parts of water. The temperature of the EVOH solution at this time is 60
℃, the water temperature is 5℃, the rotation speed of the stirring blade of the instant mixer is 3,
OOOrpm.

The precipitated resin liquid that came out of the mixing tank was in a state where the precipitated resin particles and the solvent were separated. This product was centrifuged while being washed with water to separate the solvent and precipitated resin particles. The resin particles were dried at 80° C. while being mixed gently to obtain dry resin particles of the present invention having an average particle size of 1.5 mm. The particles had a specific gravity of 0.3 g/crn' and a spherical shape.

The resin particles were spread uniformly on a stainless steel plate with a frame that had been coated with a mold release agent in advance, and pressed for 10 minutes using a press machine at a temperature of 200° C. at a pressure of 50 kg/crn' to form a mold. The molded plate was taken out and cooled to room temperature to obtain a molded body made of resin particles. This molded product was useful as a filter because it was breathable and had excellent oil resistance, organic solvent resistance, and strength.

[Brief explanation of the drawing]

Figure 1 shows the particle structure of the resin particles of the present invention at a magnification of 5.0.
This is a micrograph at 00x magnification.

Claims (5)

[Claims] (1) Porous resin particles mainly composed of ethylene-vinyl alcohol copolymer. (2) The resin particles according to claim 1, containing a polyamide resin. (3) The resin particles according to claims 1 and 2, which have a particle size of 2 mm or less. (4) The resin particles according to claims 1 and 3, which have a substantially spherical shape. (5) A method for producing porous resin particles, which comprises dissolving a resin whose main component is an ethylene-vinyl alcohol copolymer in a solvent, precipitating resin particles by mixing with a poor solvent or lowering the temperature, and then drying. .