JPH0460696B2 - - Google Patents

Description

[Detailed description of the invention] Industrial applications The present invention relates to a method for producing composite particles.

Conventional technology Conventionally, methods for producing particles (granulation) include rolling granulation, in which wet raw materials are granulated by rolling motion of a container, and compressive stress is applied to dry or wet raw materials filled in a container. Compression granulation, which involves molding, extrusion granulation, which involves extruding humidified and fluidized raw materials through a die or wire gauze, and forming them into a cylindrical or granular shape; Fluidized granulation, in which the humidified raw material is fed to a rotating blade and crushed by applying shearing force, Mixed granulation, in which the humidified raw material is processed and granulated using a solid mixer. In addition to physical granulation, such as injection granulation, in which a molten liquid is dispersed into droplets and cooled and solidified in air to form spherical particles, chemical granulation, in which fine particle polymers are obtained through emulsion polymerization, suspension polymerization, etc. is being carried out.

Problems to be Solved by the Invention However, with these conventional particle manufacturing methods, it is possible to produce particles ranging from fine to large particles as required; however, when observing the physical structure of the particles, the structure Generally, the specific surface area relative to the particle size is small, and its uses are limited.

For example, polymer particles obtained by suspension polymerization are expected to be highly efficient when applied to chromatography as carriers for substance separation, especially selective substance separation, but they are used by filling columns. It is difficult to obtain a sufficient surface area for chromatography, and if the particle size of the polymer particles is reduced in order to obtain this surface area, there is a problem in that the flow rate of the liquid flowing through the chromatography becomes small.

Furthermore, with particles obtained by conventional particle manufacturing methods, it is difficult to impart appropriate surface properties as necessary.

With these conventional technical problems as a background, the present inventors have conducted intensive studies with the aim of producing particles that have a large specific surface area relative to the particle diameter and can easily obtain appropriate surface characteristics. The present invention was achieved based on the discovery that strongly fixed composite particles can be obtained by combining the following.

Means for Solving the Problems That is, the present invention provides particles with a particle size R ₁ of 1 to 500 μm and a standard deviation of the particle size distribution of ±40% or less of the average particle size, and an organic polymer that is different from the material of the particles. Made of molecular substance, particle size _R2 is 0.05 to 10 μm, standard deviation of particle size distribution is ±40% or less of average particle size, and particle size ratio
Particles satisfying R ₂ /R ₁ of 1/10 or less are mixed under conditions where the particles and the particles themselves are not substantially crushed, and compressive force and shear force are applied to the surface of the particles. The present invention provides a method for producing composite particles, which is characterized by fixing a plurality of particles.

First, the material and shape of the particles serving as the base particles are not particularly limited, but the material is different from the material of the particles. If the materials of the particles are different, when the two are mixed in an insulating state in the mixing process described later, the surfaces of the two tend to be charged with different charges, and the particles tend to stick to the particles. If the particles are made of the same material, this effect will be low.

The materials of the particles include glass, silica, iron,
Inorganic materials such as copper, aluminum, nickel, stainless steel, iron oxide, ferrite, carbon black, polyethylene, polypropylene, polystyrene, polymethyl methacrylate, polyvinyl chloride, nylon 6, nylon 12, epoxy resin, phenolic resin, cellulose, Examples include organic polymer substances such as starch.

Although the shape may be any shape such as spherical or elliptical, a spherical shape is preferable in that the particles are uniformly fixed and bonded. Furthermore, the structure may be hollow or porous to the extent that it does not easily break.

The particle size R ₁ of the particles, if the shape is elliptical, the major axis diameter is 1 to 500 μm, preferably 1 to 100 μm,
Particularly preferably 3 to 50 μm, and the standard deviation of the particle size distribution is ±40% or less of the average particle size.

If the particle size of the particles is less than 1 μm, it may not be possible to obtain uniform composite particles, considering that the particle size described later, that is, the particle size ratio R ₂ / R ₁ is 1/10 or less.
On the other hand, if the diameter exceeds 500 μm, the surface activity of the particles will be low, making it difficult for the particles to adhere to the particle surface.

The standard deviation of the particle size distribution of particles is not as important as that of particles, but it is necessary to be within ±40% of the average particle diameter in order to obtain composite particles in the present invention.

Next, as for the material of the particles, in addition to the organic polymer substances listed for the particles, organic polymer substances obtained from various vinyl monomers, diene monomers, etc. can be exemplified. The material on which it rests needs to be different from the particles.

Like the particles, the shape and structure of the particles are not particularly limited.

The particle size R ₂ of the particles is 0.05 to 10 μm, preferably 0.1 to 5 μm, and the standard deviation of the particle size distribution is 40% or less of the average particle size, preferably 10
% or less, and furthermore, the particle size ratio R ₂ /R ₁ is 1/10 or less, preferably 1/10 to 1/1000, and even more preferably 1/10.
~1/100.

If the particle size is less than 0.05 μm, the particle size is too small to take advantage of the surface properties of the resulting composite particles, while if it exceeds 10 μm, uniform composite particles may not be obtained.

Furthermore, in the phenomenon of particles sticking to particle surfaces, it is thought that particles with higher surface activity, that is, particles with smaller particle sizes, adhere first, so it is better that the standard deviation of the particle size distribution of particles is as narrow as possible.
Therefore, it is necessary to keep the average particle size at least 40% or less, preferably 10% or less; if it exceeds 40%, the composite particles obtained will have irregular large particles fixed on the outermost side to achieve the desired surface characteristics. It is difficult to do so.

Furthermore, the state of adhesion of particles to particles is influenced by the particle size ratio of the two, and when the particle size ratio R ₂ /R ₁ exceeds 1/10, the particle size of the particles becomes larger than the particle size of the particles. As a result, the particles once fixed are likely to be peeled off by a minute external force.

Particles made of such organic polymer substances are
In addition to chemical granulation methods such as emulsion polymerization method, suspension polymerization method, and precipitation polymerization method, spray drying method, submerged drying method,
It can be produced by a physical granulation method such as a pulverization method or a precipitation method from a polymer solution.

In order to utilize various surface properties at the same time, the particles may be made of a mixture of two or more organic polymeric substances, or if necessary, particles made of two or more different organic polymeric substances may be used. They can also be used together.

Note that the weight ratio between particles varies depending on the particle size of the particles to be combined, but it is usually 10 to 200 parts by weight of particles to 100 parts by weight of particles, for example, particles with a particle size of about 10 μm.
When surrounding with particles of about 0.5 μm and utilizing the surface characteristics of the particles, the amount of particles is preferably 20 to 100 parts by weight per 100 parts by weight of the particles. In this case,
A single layer to two or three layers of particles can be surrounded on the surface of the particles.

In the present invention, the particles thus specified and the particles are then mixed together under conditions in which both particles do not substantially fracture, and compressive force and shear force, impact force if necessary, and more preferably inter-particle By applying twisting frictional force, a plurality of particles are fixed to the surface of the particles.

The particles are usually mixed by dry mixing, but the mixing system may be slightly moist.

When mixing particles, it is preferable that the mixing container is insulated and the mixing system is placed under insulation to facilitate charging of the particles.

In other words, by being electrically charged, particles repel each other and do not agglomerate, while particles are made of different materials, so they usually have different charge types and are attracted to each other, causing particles to adsorb and stick to the surface of the particles. It is thought that this phenomenon occurs.

By mixing particles, the particles become surrounded by particles, but after the particles adhere to the particles, if the mixing is continued, the particles become tightly bonded, and for example, the resulting composite particles are dispersed in water. Also, both will not peel off.

This phenomenon occurs when particles come into point contact during mixing, and compressive force, shearing force, impact force in some cases, and even twisting friction force between particles act at the contact point, causing temporary damage at the contact point. For example, about 1000℃
This is thought to be because heat is generated instantaneously in the front and back, causing a sticking phenomenon due to fusion.

In this sticking phenomenon, if the particle has a higher melting point, the particle will stick in a state where it sinks into the particle surface, whereas if the particle has a higher melting point, the particle will stick in a state where it sinks into the surface of the particle. It can also be considered a thing.

The mixing temperature between the particles may be such that the particles and the particles themselves do not melt, but they are usually mixed at room temperature.

Examples of mixing means when carrying out the present invention include:
In addition to the method using a mortar, solid mixers such as V-shaped tumblers and double cone tumblers, kneader mixers, internal mixers, pony mixers,
Examples include a method using a kneading machine such as a Mueller mixer, a roll mill, or a crutcher, or a general agitator such as a paddle-type agitator, a turbine-type agitator, or a Henschel mixer.

By using the above-mentioned mixing means, it is usually possible to mix particles under conditions that do not cause substantial fragmentation of the particles, and in this case, compressive force and shear force between the particles can be applied as necessary. An impact force, more preferably a twisting friction force between particles, can be applied depending on the size of the particles.

If a mortar is used here, the particle size of the particles is
The diameter is preferably about 10 μm or less, and mixing is usually performed for 30 to 120 minutes. In this case, if the mixing time is less than 30 minutes, the adhesion between the particles may not be sufficient, and if the particles are mixed for too long, the shape of the particles or particles may be deformed if the heat distortion temperature of the particles is low.

In the case of other mixing methods, the particle diameters of the particles are not particularly limited as long as they are within the scope of the present invention, but it is necessary to appropriately select the mixing time as in the case of using a mortar.

In this way, by surrounding and fixing one or more layers of particles with a smaller particle size than the particle on the surface of the particle, the surface area of the particle increases several times or more despite a slight increase in the particle size, and surface properties can be imparted to the particles.

That is, particles are made of organic polymeric substances, and their surface properties vary. For example, if particles are manufactured by emulsion polymerization, carboxyl groups, hydroxyl groups, Functional groups such as sulfonic acid groups, amino groups, epoxy groups, chloromethyl groups, methylol groups, and amide groups can be introduced, and by using such particles, various functional groups can be introduced onto the surface of the particles. The surface properties of the particles can be changed.

Furthermore, if the present invention is applied when the particles are hydrophobic and it is desired to disperse the particles in a hydrophilic medium, or vice versa, the hydrophilicity and hydrophobicity of the particles can be reversed by the above-mentioned means, and it is easy to disperse the particles in a hydrophilic medium. Becomes dispersed.

As described above, the present invention can be said to be an extremely useful means in cases where the particles do not have the necessary surface properties, and the particle size alone is too small to be put to practical use.

Action Particles and particles with a smaller particle size are mixed, and the high heat instantaneously generated by the compressive force and shear force acting on the contact point of both particles during mixing melts and solidifies the contact point. The particles surround the surface of the particles, thus improving the surface properties of the particles.

Examples Next, the present invention will be explained in more detail with reference to Examples.

Example 1 70 g of polyethylene particles with an average particle size of 5 μm and a standard deviation of particle size distribution of 40% of the average particle size, and
0.3 μm, the standard deviation of the particle size distribution is 3% of the average particle size, and the amount of carboxy groups on the particle surface is
30 g of polystyrene particles of 0.056 meq/g were mixed at 25° C. for 60 minutes using an automatic mortar.

As a result, the polystyrene particles adhered to the polyethylene particles and completely covered the surface, as is clear from the electron micrograph in FIG. 1 (magnification: 10,000 times).

In addition, the obtained composite particles can be easily dispersed in water,
Even with vigorous stirring, no peeling of the polystyrene particles was observed.

Example 2 90 g of styrene-divinylbenzene copolymer particles with an average particle size of 200 μm and a standard deviation of particle size distribution of 25% of the average particle size, and 90 g of styrene-divinylbenzene copolymer particles with an average particle size of 0.31 μm and a standard deviation of particle size distribution of 1% of the average particle size. % and 10 g of styrene-glycidyl methacrylate copolymer particles with 0.033 meq/g of primary amino groups introduced onto the particle surface were placed in a V-shaped tumbler, and 12
Shake and mix for 24 hours at a rotating speed.

As a result, as in Example 1, composite particles were obtained in which styrene-glycidyl methacrylate copolymer particles were adhered to styrene-divinylbenzene copolymer particles, and a large amount of about 1 particle per 1 nm ² was formed on the surface of the particles without functional groups. Composite particles were obtained which were provided with primary amino groups.

Example 3 70 g of glass particles with an average particle size of 5 μm and a standard deviation of particle size distribution of 40% of the average particle size, and
0.3 μm, the standard deviation of the particle size distribution is 3% of the average particle size, and the amount of carboxy groups on the particle surface is
30 g of polystyrene particles of 0.056 meq/g were mixed at 25° C. for 60 minutes using an automatic mortar.

As a result, the polystyrene particles adhered to the glass particles and completely covered the surface, as is clear from the electron micrograph shown in FIG. 2 (magnification: 10,000 times).

Furthermore, the obtained composite particles were easily dispersed in water, and no peeling of the polystyrene particles was observed even when vigorously agitated.

Effects of the Invention According to the present invention, by combining specific particles and particles, it is possible to easily obtain composite particles having particles fixed to the surface of the particles, having a large specific surface area relative to the particle diameter, and having appropriate surface characteristics. I can do it.

[Brief explanation of drawings]

FIGS. 1 and 2 are electron micrographs (10,000 times magnification) of composite particles (particle structure) obtained according to one embodiment of the present invention.

Claims (1)

[Claims] 1. Particles with a particle size R ₁ of 1 to 500 μm and a standard deviation of particle size distribution of ±40% or less of the average particle size, and an organic polymer substance different from the material of the particles, and a particle size R ₂ of 0.05 to 500 μm. 10 μm, the standard deviation of the particle size distribution is ±40% or less of the average particle size, and the particle size ratio R ₂ / R ₁ is 1/10
A plurality of particles are fixed to the surface of the particles by mixing the particles and particles satisfying the following conditions under conditions where the particles and the particles themselves are not substantially crushed, and applying compressive force and shear force. A method for producing composite particles.