JP2837091B2 - Method for producing colored polymer fine particles - Google Patents

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 fine polymer particles for cosmetics, fillers, coloring materials, for example, a liquid developer for electrophotography or a polymer fine particle additive.

[0002]

2. Description of the Related Art As a method for producing colored polymer fine particles for cosmetics, fillers, coloring materials, etc., a pulverization method of mechanically pulverizing a resin by wet pulverization, dry pulverization, etc., a dispersant, a surfactant, and the like. , A polymerization method using an unreacted monomer and the like are provided.

Japanese Patent Application Laid-Open No. Hei 4-226478 discloses a method for producing a high gloss electrostatic liquid developer by setting a temperature in an apparatus in which a thermoplastic resin, a pigment and a hydrocarbon liquid are dispersed within a certain range for a certain period of time. A method of maintaining is disclosed.

[0004]

In the conventional pulverization method, the resin is mechanically pulverized, so that the particle size distribution is broadened, the yield of fine particles having a desired particle size is reduced, and the particle shape is reduced. Is not uniform, and it is almost impossible to efficiently obtain fine particles having a particle size of 5 μm or less.

In the case of the above-mentioned polymerization method, it is substantially difficult to control the polymerization conditions, and the dispersant, surfactant, unreacted monomer and the like used in the polymerization adhere to the surface of the produced colored polymer fine particles. It is inevitable to do.
Further, when the colored polymer fine particles produced by the above polymerization method are used as various functional materials, it is an essential step to remove impurities on the surface of the fine particles and purify them. However, as the particle diameter becomes smaller, the purification becomes more difficult.

In the method for producing a high gloss electrostatic liquid developer disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 4-226478, the fineness of the particles is exclusively performed by wet pulverization. No method has been adopted for producing colored polymer fine particles without going through.

An object of the present invention is to provide colored polymer fine particles having an average particle diameter of 10 μm or less on the principle completely different from the above-mentioned pulverization method, polymerization method and the like, and without going through mechanical pulverization and / or classification steps. Is to provide a production method capable of efficiently obtaining

[0008]

Means for Solving the Problems The first feature of the present invention is to produce colored polymer fine particles in the order of the following steps (A) to (C).

Step (A): An olefin polymer having at least one polar group selected from an ester group and / or a carboxyl group, a hydroxyl group and an amino group in a non-aqueous solvent, and at least one colorant. Disperse. Step (B): maintaining the temperature of the solvent or the solution in a temperature range (T1) to (T1 + 10 ° C.) at which the polymer dissolves in the solvent for 10 minutes to 240 minutes. Step (C): Coloring fine particles of the polymer are precipitated by lowering the solubility of the polymer in the solvent.

After the step (B), the following (B)
1) The step (C) is performed through the step 2
The feature is. Step (B1): temperature of the solvent or solution (T0 ° C.)
At a temperature at least 20 ° C. higher than the temperature at which the polymer dissolves in the solvent (T1 ° C.), ie, (T1 + 20 ° C.), and the solvent boils or decomposes, or the resin and / or
Alternatively, the temperature is maintained at a temperature equal to or lower than the temperature at which the coloring material decomposes (T2 ° C.), that is, in a temperature range of T1 + 20 ° C. < T0 < T2 for 5 minutes to 90 minutes.

The method for producing the colored polymer fine particles according to the present invention having the above-described constitution will be described in more detail. According to the present invention, the average particle diameter of the colored polymer fine particles can be adjusted to 50 by the step (B) without mechanical pulverization and classification.
It can be controlled to less than μm, especially less than 10 μm.

Further, by adding the step (B1) between the steps (B) and (C), it is possible to prevent the precipitation of polymer-only particles containing no pigment.

The polymer used in the method of the present invention may be an ester group and / or a carboxyl group, a hydroxyl group,
An olefin-based polymer having at least one kind of polar group selected from an amino group, comprising ethylene, a vinyl acetate copolymer, an ethylene / (meth) acryl copolymer,
There are (meth) acrylate polymers, styrene / (meth) acrylate copolymers, and modified products thereof. In the present invention, one of these may be used alone, or two or more of them may be used as a mixture.

As the coloring material used in the method of the present invention, pigments usually used for coloring materials, for example, carbon black, phthalocyanine blue, phthalocyanine green, sky blue, rhodamine lake, malachite green lake, Hansa yellow , Benzidine yellow, brilliant carmine 6B and the like.

The above pigments can be used in combination with the following dyes. That is, oil-soluble azo dyes such as oil black and oil red, basic azo dyes such as bismark brown, acidic azo dyes such as blue black HF, and quinone imine dyes such as nigrosine.

Further, the non-aqueous solvent used in the method of the present invention may be a single solvent or a mixed solvent. Examples of usable solvents include straight-chain and / or branched-chain aliphatic hydrocarbons, halogenated aliphatic hydrocarbons, aromatic hydrocarbons, and straight-chain or branched-chain aliphatic alcohols having 12 or less total carbon atoms. , Can be used alone or in combination of two or more. Further, additives such as a surfactant and a dispersant may be added as necessary.

[0017]

The main object of the present invention is to have an average particle diameter of 50 μm or less.
In particular, in order to obtain colored polymer fine particles having an average particle size of 10 μm or less without performing mechanical pulverization and classification operations as in the conventional method, it is most preferable to carry out the steps (B) and (C) in combination. It is effective.

That is, by maintaining the temperature of the solvent containing the polymer and the pigment near the temperature (T1) at which the polymer begins to dissolve in the solvent, the polymer is gradually dissolved and the concentration of the dissolved polymer (solubility) in the solvent is reduced. When the polymer is adsorbed on the surface of the pigment while holding the pigment, the thickness of the polymer adsorption layer on the surface of the pigment is increased, and the dispersibility of the pigment is improved.

In order to keep the concentration of the dissolved polymer low, it is preferable to maintain the temperature of the solvent at a temperature slightly higher than the temperature (T1) at which the polymer begins to dissolve in the solvent. And so on. Considering such a variation in temperature control (about 10 ° C.), maintaining the temperature of the solvent in the above temperature range of T1 to T1 + 10 ° C. is sufficient to obtain the colored polymer fine particles of the present invention. It was confirmed.

It is well known that the adsorption of a polymer takes longer than the adsorption of an inorganic substance, and that the time required to complete the adsorption depends on the combination of the pigment and the resin. The polymer adsorption time is about 10 minutes for a system having a short adsorption time, and about 240 minutes for a system having a long adsorption time.
It was confirmed that when the temperature was kept at 10 ° C., the dispersibility of the pigment was improved due to the formation of the polymer adsorption layer. It should be noted that even if the temperature range is maintained for 240 minutes or more, the effect is flat, and there is no advantage from the viewpoint of economic efficiency such as manufacturing cost.

By performing the steps described above,
In the step (C), the aggregation of the pigment is unlikely to occur when the polymer is precipitated with the pigment as a nucleus. Therefore, the average diameter of the precipitated colored polymer fine particles is 50 μm or less, particularly 10 μm or less.
m or less.

Further, in order to suppress the precipitation of polymer-only particles which do not include a pigment, the steps (B) and (C)
It is effective to perform the step (B1) between the steps.

That is, in the vicinity of the temperature at which the polymer begins to dissolve in the solvent, although the polymer contains, in addition to the pigment, a seed which can be a nucleus at the time of precipitation of the polymer particles, the temperature of the solvent is increased once. As a result, seeds that can be nuclei other than pigments are destroyed, so that it is possible to suppress the precipitation of polymer-only particles not having pigments as nuclei.

In the step (B1), the temperature at which the polymer is dissolved in the solvent (T1) or 20 ° C. higher than this temperature.
In a temperature range of a high temperature (T1 + 20 ° C.), the polymer core may actually remain even though the polymer seems to be completely dissolved.

The inventors have eliminated such a problem,
In order to completely dissolve the seed of the polymer that can be a core, at least 20 minutes higher than the temperature (T1) at which the polymer dissolves in the solvent (T1 + 20 ° C.), 5 minutes or more in a system in which the seed of the polymer is easily dissolved, It was confirmed by an experiment shown in the examples that the effect of suppressing the precipitation of polymer-only fine particles when maintained for 90 minutes even in a system that is difficult to dissolve was confirmed. If the above maintenance time exceeds 90 minutes, thermal denaturation of the pigment may occur, and there is no advantage in terms of economic efficiency such as extension of the processing time.

[0026]

Embodiments of the present invention will be described below in detail. [Example 1] 5 parts of oil-based nigrosine (dye) (manufactured by Daiwa Kako Co., Ltd.) was dissolved in 100 parts of ethanol, and then 25 parts of carbon black MA-7 (pigment) (manufactured by Mitsubishi Kasei) were added. Irradiate ultrasonic waves for 20 minutes to sufficiently disperse the carbon black. Then, the temperature was kept at 40 ° C. by an evaporator, the pressure was reduced, and the ethanol was distilled off. The cake was roughly pulverized in a mortar and then pulverized in a bead mill to obtain a cake.
Nigrosine-treated MA-7 having a particle size of 8 μm was obtained.

Next, nigrosine-treated MA-7: 4 was placed in a container equipped with a stirrer, thermometer, reflux condenser and vacuum deaerator.
Parts, Isopar G (manufactured by Esso Sekiyu KK) which is a branched aliphatic hydrocarbon: 720 parts, toluene (manufactured by Katayama Chemical) as an aromatic hydrocarbon: 480 parts, ethanol (manufactured by Katayama Chemical) as an aliphatic alcohol: 300 parts, Dumilan C-5 as a partially saponified ethylene-vinyl acetate copolymer
791 (manufactured by Takeda Pharmaceutical Co., Ltd.): 20 parts and Zr-naphthanate (manufactured by DIC): 20 parts as a metal soap. After holding at 120 ° C. for 120 minutes while stirring at a high temperature of 50 ° C., and then holding at 80 ° C. for 30 minutes, the vessel was evacuated to vacuum while keeping the liquid temperature at 50 ° C.
Colored polymer fine particles were precipitated by distilling off toluene and ethanol.

FIG. 1 shows the results of measuring the particle size distribution of the colored polymer fine particles thus obtained using a laser diffraction / scattering type particle size distribution analyzer LA-700 manufactured by Horiba Seisakusho. In FIG. 1, the vertical axis (R) on the right side is the integrated percentage of particles.
Corresponds to the curve in the figure, and the vertical axis (F) on the left side corresponds to the bar graph in the figure with the frequency% for each particle diameter. The median diameter is the average particle diameter, and the specific surface area is the surface area of the particles per 1 cm ² . Particle size%: 10.00 μm = 0.00%
The ratio of particles having a particle diameter of 10.00 μm or more is 0.0%, and the% particle diameter: 90.0% = 1.457 μm is 1.4%.
Those having a size of 57 μm or more represent 90%. FIG.
From the results, it can be seen that the colored polymer fine particles obtained in Example 1 have a sharp particle size distribution of 50% by volume (median diameter) of 2.449 μm.

Comparative Example 1 Colored polymer fine particles were precipitated in the same manner as in Example 1 except that the step of holding at 50 ° C. for 120 ° C. was omitted. The result of measuring the particle size distribution in the same manner as in Example 1 is shown in FIG. FIG. 2 has the same meaning as FIG. As a result of FIG. 2, the polymer fine particles obtained in Comparative Example 1 had a volume-based 50% particle diameter (median diameter) of 12.637 μm.

Comparative Example 2 Colored polymer fine particles were precipitated in the same manner as in Example 1 except that the step of holding at 80 ° C. for 30 minutes was omitted. The result of measuring the particle size distribution in the same manner as in Example 1 is shown in FIG. FIG. 3 has the same meaning as in FIG. As shown in the figure, the fine particles obtained in Comparative Example 2 are a mixture of a colored polymer fine particle having a peak at around 2 μm and a resin fine particle and a pigment having a peak at around 0.3 μm, and have a 50% particle diameter based on volume (median). (Diameter) 1.167 μm.

[Embodiment 2] In the embodiment 1, the liquid temperature was set to 5
Instead of vacuum degassing the vessel while keeping it at 0 ° C, 18
Colored polymer fine particles were precipitated in the same manner as in Example 1 except that the liquid temperature was cooled from 80 ° C. to 30 ° C. over a period of 0 minutes. The obtained colored polymer fine particles had a volume-based 50% particle size (median size) of 2.951 μm.

The mixed solvent in the dispersion medium of the colored polymer fine particles was replaced with Isopar G, and a common additive such as a charge-imparting agent was added to obtain an electrophotographic liquid developer (solid content: 3%). This developer was placed in a commercially available wet electrophotographic copying machine, and a copy was made on a commercially available high-quality paper.
An excellent image having a transfer rate of 94% and a background smear of 0.01 D or less was obtained. Note that a Macbeth densitometer was used for the measurement of density and background contamination. The transfer rate was determined by the following equation.

Example 3 Instead of adding 25 parts of phthalocyanine blue (Dainichi Seika) instead of carbon black MA-7 in Example 1, and evacuating the vessel while maintaining the liquid temperature at 50 ° C. Then, colored polymer fine particles were precipitated in the same manner as in Example 1 except that 200 parts of Isopar G was added while maintaining the liquid temperature at 50 ° C. The obtained colored polymer fine particles had a volume-based 50% particle size (median size) of 4.710 μm.

[0034]

As described above, the present invention has the following effects. (1) An average particle size of 50 by a relatively simple manufacturing method without going through a conventional mechanical pulverizing and / or classifying operation.
It is possible to produce colored polymer fine particles having a size of at most 10 μm, especially at most 10 μm. (2) The production of colored polymer fine particles in which the pigment is uniformly dispersed can be suppressed by suppressing the generation of the polymer-only particles containing no pigment. (3) Unlike the conventional polymerization method, the surface of the generated particles is not contaminated by adsorption of impurities and the like, and post-treatment is easy.

[Brief description of the drawings]

FIG. 1 is a particle size distribution diagram of colored polymer fine particles according to Example 1 of the present invention.

FIG. 2 is a diagram corresponding to FIG.

FIG. 3 is a diagram corresponding to FIG.

FIG. 4 is a diagram corresponding to FIG. 1 according to the second embodiment.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-5-70596 (JP, A) JP-A-61-223059 (JP, A) JP-A-51-34928 (JP, A) (58) Field (Int.Cl. ⁶ , DB name) C08J 3/12-3/16 C08L 23/26

Claims (2)

(57) [Claims] An olefin polymer having at least one kind of polar group selected from an ester group and / or a carboxyl group, a hydroxyl group and an amino group, and at least one kind of coloring material are dispersed in a non-aqueous solvent. , The temperature of the solvent, the temperature at which the polymer dissolves in the solvent (T1)
Or a temperature (T1 + 1) higher than the temperature (T1) by 10 ° C.
(0 ° C.) for 10 minutes to 240 minutes, thereby lowering the solubility of the polymer in the solvent to precipitate colored polymer fine particles. 2. An olefin polymer having at least one kind of polar group selected from an ester group and / or a carboxyl group, a hydroxyl group and an amino group, and at least one kind of coloring material are dispersed in a non-aqueous solvent. , The temperature of the solvent, the temperature at which the polymer dissolves in the solvent (T1)
Or a temperature (T1 + 1) higher than the temperature (T1) by 10 ° C.
0 ° C.) for 10 minutes to 240 minutes, and the solution in which the solvent or polymer is dissolved is at a temperature 20 ° C. or more higher than the temperature (T1) at which the polymer dissolves in the solvent, and the solvent is boiled or Maintained at a temperature range of a decomposition temperature or a temperature range (T0) lower than a temperature (T2) at which the resin or the coloring material decomposes, for 5 minutes to 90 minutes,
A method for producing colored polymer fine particles, wherein the polymer has low solubility in the solvent to precipitate colored fine particles of the polymer.