JP2891634B2 - Method for producing polymer microcapsules - 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 polymer microcapsules containing fine particles such as pigments and ceramics.

[0002]

2. Description of the Related Art Conventionally, there are a resin reprecipitation method and a polymerization method as a method for producing polymer microcapsules in a non-aqueous solvent.

[0003]

In the resin reprecipitation method, for example, there is a method in which an olefin resin kneaded with a coloring agent is heated and dissolved in toluene, and then cooled to precipitate colored particles. The method is not a method of adding a resin dissolved by heating to a non-aqueous solvent in which fine particles such as pigments and ceramics are dispersed. It is not a method of controlling the particle size by changing the solubility parameter of the non-aqueous solvent (hereinafter referred to as SP value).

Although there are many examples of producing polymer microcapsules in an aqueous system by the above polymerization method, there are few examples of polymerization in a non-aqueous solvent, and it is difficult to control the polymerization conditions. In addition, on the surface of polymer microcapsules produced by polymerization method,
When using microcapsules as various functional materials, unavoidable attachment of dispersants, surfactants, polymerization initiators, unreacted monomers, etc., it is necessary to remove those impurities and purify them. There was a problem that purification became difficult.

The present invention has been made in view of the above problems, and its object is to form a polymer microcapsule having an arbitrary particle size with good reproducibility and to easily perform post-processing. It is an object of the present invention to provide a method for producing a polymer microcapsule in which the polymer microcapsule can be easily dispersed in a vehicle of an ink or a coating or in an organic solvent.

[0006]

Means for Solving the Problems In order to achieve the above object, the method for producing a polymer microcapsule of the present invention comprises dispersing fine particles in a non-aqueous solvent, heating and mixing the fine particles, and adding the fine particles to the dispersion in advance. A solution prepared by heating and dissolving the ethylene copolymer in an aqueous solvent is added, and the solution after the addition is further heated and mixed at a temperature equal to or higher than the dissolution temperature of the ethylene copolymer, and then cooled and deposited. It is characterized by the following (claim 1).

The method for producing a polymer microcapsule according to claim 1, wherein the ethylene-vinyl acetate copolymer is hardly soluble or insoluble in a non-aqueous solvent at room temperature as an ethylene copolymer and is dissolved in the non-aqueous solvent by heating. ,
At least one of ethylene vinyl acetate copolymer partially saponified product, ethylene acrylic acid copolymer and ethylene acrylate copolymer may be used (claim 2). Further, the method for producing a polymer microcapsule of the present invention is an ethylene copolymer in which fine particles such as pigments and ceramics are dispersed in a non-aqueous solvent and mixed by heating, and the dispersion is coated with the fine particles in advance in a non-aqueous solvent. Is heated and dissolved, and the liquid after the addition is further heated to a temperature equal to or higher than the melting temperature of the ethylene copolymer to be mixed and dispersed.
It is characterized by being precipitated by cooling (Claim 3).

In the method for producing a polymer microcapsule according to the third aspect, the solubility parameter of the non-aqueous solvent (S
The particle diameter may be controlled by changing the (P value) (claim 4). 5. The method for producing a polymer microcapsule according to claim 3, wherein the non-aqueous solvent is a linear or branched aliphatic hydrocarbon, an aromatic hydrocarbon,
A single or a mixed solvent of two or more of linear or branched aliphatic alcohols having 10 or less carbon atoms may be used (claim 5).

The method for producing a polymer microcapsule according to any one of claims 3 to 5, wherein the ethylene copolymer has a melt index of 50 or more and a molecular weight of 10,000.
Not more than 100.000 and insoluble or insoluble at room temperature in the non-aqueous solvent and dissolved in the non-aqueous solvent by heating, ethylene-vinyl acetate copolymer ethylene-vinyl acetate copolymer partially saponified, ethylene At least one of an acrylic acid copolymer and an ethylene acrylate copolymer may be used (claim 6).

[0010]

According to the method for producing a polymer microcapsule of the present invention, as described above, fine particles (eg, pigments, ceramics, etc.) are dispersed in a non-aqueous solvent and mixed by heating. A liquid obtained by heating and dissolving the polymer is added, and the liquid after the addition is further heated to a temperature equal to or higher than the melting temperature of the ethylene copolymer to be mixed and dispersed, and then cooled to precipitate polymer microcapsules. . In the non-aqueous solvent in which the fine particles are dispersed, by adding the dissolved ethylene copolymer, the adsorption of fine particles to the powder or pellet surface, which occurs when the ethylene copolymer is added in the form of powder or pellets, for concentration Due to this, it is possible to suppress the generation of fine particle aggregates, and as a result, it is possible to easily reduce the particle size of the polymer microcapsules and sharpen the particle size distribution. The particle size of the polymer microcapsules can be controlled by changing the SP value of the non-aqueous solvent and adjusting the affinity between the ethylene copolymer and the non-aqueous solvent.
The smaller the difference in SP value between the ethylene copolymer and the non-aqueous solvent, the smaller the particle size of the polymer microcapsules.
The larger the difference in P value, the larger the particle size.

[0011]

EXAMPLES (First Example) Of two containers equipped with a stirrer, a thermometer, and a reflux condenser, one of the containers 1 contains a branched-chain aliphatic hydrocarbon Isobar G (manufactured by Exxon): 162 parts Aroma Aromatic hydrocarbon Toluene (manufactured by Katayama Chemical Co., Ltd.): 108 parts Aliphatic alcohol Ethanol (manufactured by Katayama Chemical Co., Ltd.): 270 parts was charged to obtain a nonaqueous solvent having an SP value of 10.73. To this, 4.8 parts of pigment Carmine B6 (manufactured by Dainichi Seika Kogyo Co., Ltd.) was added, and mixed and dispersed at 70 ° C. In the other container 2, branched chain aliphatic hydrocarbon Isopar G (manufactured by Exxon): 378 parts Aromatic hydrocarbon Toluene (manufactured by Katayama Chemical): 252 parts Aliphatic alcohol Ethanol (manufactured by Katayama Chemical): 630 parts It was charged to obtain a non-aqueous solvent having an SP value of 10.73. Among them, ethylene-vinyl acetate copolymer partially saponified product Dumilan C-2280 (SP value: 8.9, manufactured by Takeda Pharmaceutical Co., Ltd.)
3): 24 parts (powder) were added and mixed at 70 ° C. to completely dissolve Dumilan.

After adding the dumilan solution at 70 ° C. in the other container 2 to the pigment dispersion in one container 1 over 20 minutes, the mixture in one container 1 is mixed and dispersed at 70 ° C. for 30 minutes. Then, the mixed solution in one container 1 is cooled to room temperature by 180.
By cooling over a period of minutes, polymer microcapsules containing the pigment were formed. The polymer microcapsules thus obtained had a volume-based 50% particle size of 2.4 μm (see FIG. 1).

Next, a comparative example of the first embodiment will be described. In a vessel equipped with a stirrer, thermometer and reflux condenser, branched aliphatic hydrocarbon Isopar G (manufactured by Exxon): 540 parts Aromatic hydrocarbon Toluene (manufactured by Katayama Chemical): 360 parts Aliphatic alcohol Ethanol (Katayama) (Manufactured by Kagaku Co.): 900 parts were added to obtain a non-aqueous solvent having an SP value of 10.73. Among them, ethylene-vinyl acetate copolymer partially saponified product Dumilan C-2280 (SP value: 8.9, manufactured by Takeda Pharmaceutical Co., Ltd.)
3): 24 parts (powder), 4.8 parts of pigment Carmine B6 (manufactured by Dainichi Seika Kogyo Co., Ltd.) were added and mixed and dispersed at 70 ° C. to completely dissolve Dumilan, and then cooled to room temperature over 180 minutes. As a result, a polymer microcapsule containing a pigment was formed. The polymer microcapsules thus obtained have a volume-based 50% particle size of 10.8.
μm (see FIG. 2).

(Second Embodiment) Polymer microcapsules were formed in the same manner as in the first embodiment except that the composition of the nonaqueous solvent in the containers 1 and 2 was changed as shown in Table 1. Table 1 also shows the 50% particle size based on volume of the polymer microcapsules thus obtained. FIG. 3 shows the relationship between the SP value of the non-aqueous solvent and the average particle size of the polymer microcapsules. Table 1 also shows the first example (when the solvent SP value is 10.73).

[0015]

[Table 1] (Third Embodiment) In the first embodiment, the composition of the non-aqueous solvent in the container 1 was 238 parts for Isopar G, 158 parts for toluene,
Ethanol: changed to 144 parts (non-aqueous solvent SP value: 9.54), and instead of Dumilan C-2280, partially saponified ethylene-vinyl acetate copolymer Dumilan C-5791
(Takeda Pharmaceutical Co., Ltd.): 24 parts (powder), the composition of the non-aqueous solvent in the container 2 was 554 parts for Isopar G, and 370 parts for toluene.
Parts, ethanol: 336 parts (non-aqueous solvent SP value 9.54)
A polymer microcapsule (red) dispersion having a 50% volume-based particle size of 2.4 μm was obtained in the same manner except that the above was changed.

The mixed solvent in the dispersion was replaced with Isobar G, and conventional additives such as a charge-imparting agent were added to obtain an electrophotographic liquid developer (fixed amount: 3%). When this developer was placed in a commercially available wet electrophotographic copying machine and copied on a commercially available coated paper, an excellent image having an image density of 1.52 ^D , a transfer rate of 98%, and a background smear of 0.01 ^D or less was obtained. Was. The concentration,
A Macbeth densitometer was used to measure the soiling. The transfer rate was calculated by the following equation.

Transfer rate (%) = {1− (toner density on photosensitive surface after transfer / toner density on photosensitive surface before transfer)} × 1
As a comparative example, when a copy was similarly performed using an electrophotographic liquid developer CBR-310 manufactured by Dainippon Iki Chemical Industry,
The transfer rate was 85%. (Fourth embodiment) 2 equipped with a stirrer, thermometer and reflux condenser
In one of the containers, one container 1 contains a branched-chain aliphatic hydrocarbon Isobar G (manufactured by Exxon): 270 parts Aromatic hydrocarbon Toluene (manufactured by Katayama Chemical): 180 parts Aliphatic alcohol Ethanol (manufactured by Katayama Chemical) ): 90 parts was charged to obtain a non-aqueous solvent having an SP value of 8.99. 3. Pigment phthalocyanine blue (manufactured by Dainichi Seika Kogyo Co., Ltd.)
8 parts were added and mixed and dispersed at 70 ° C. In the other container 2, branched-chain aliphatic hydrocarbon Isopar G (manufactured by Exxon): 630 parts Aromatic hydrocarbon Toluene (manufactured by Katayama Chemical): 420 parts Aliphatic alcohol Ethanol (manufactured by Katayama Chemical): 210 parts It was charged to obtain a non-aqueous solvent having an SP value of 8.99. In this, ethylene / vinyl acetate copolymer Evaflex 220
(Mitsui / Dupont Chemical): 24 parts (powder) were added and mixed at 70 ° C. to completely dissolve Evaflex.

After adding the Evaflex solution at 70 ° C. in the other container 2 to the pigment dispersion in the one container 20 over 20 minutes, polymer microcapsules containing the pigment are formed in the same manner as in the first embodiment. did. The polymer microcapsules thus obtained had a volume-based 50% particle size of 2.0 μm (see FIG. 4). Next, a comparative example of the fourth embodiment will be described. In a container equipped with a stirrer, thermometer, and reflux condenser, branched-chain aliphatic hydrocarbon Isopar G (manufactured by Exxon): 900 parts Aromatic hydrocarbon Toluene (manufactured by Katayama Chemical): 600 parts Aliphatic alcohol Ethanol (Katayama) (Manufactured by Kagaku Co.): 300 parts were added to obtain a non-aqueous solvent having an SP value of 10.73. In this, ethylene-vinyl acetate copolymer Evaflex 22
0 (manufactured by Mitsui / Dupont Chemical): 24 parts (powder), pigment phthalocyanine blue (manufactured by Dainichi Seika Kogyo): 4.8
Then, after mixing and dispersing at 70 ° C. to completely dissolve Evaflex, polymer microcapsules containing a pigment were formed in the same manner as in Example 4. The polymer microcapsules thus obtained have a volumetric 5
The 0% particle size was 8.7 μm (see FIG. 5).

(Fifth Embodiment) In the fourth embodiment, 24 parts of the ethylene / vinyl acetate copolymer Evaflex 220 added to the container 2 was replaced with an ethylene / acrylate copolymer A.704 (manufactured by Mitsui / Dupont Chemical Co., Ltd.). ): Polymer microcapsules were formed in the same manner except that the amount was changed to 24 parts (powder). The polymer microcapsules thus obtained have a volume-based 50% particle size of 2.0%.
μm (see FIG. 6).

Next, a comparative example of the fifth embodiment will be described. 4th
In the comparative example of the example, the ethylene / vinyl acetate copolymer Evaflex 220 added in the container: 24 parts was changed to 24 parts (powder) of ethylene / vinyl acetate copolymer A-704 (manufactured by Mitsui / DuPont Chemical). Polymer microcapsules were formed in the same manner except that The polymer microcapsules thus obtained had a volume-based 50% particle size of 9.8 μm (see FIG. 7).

The ethylene copolymer used in the method for producing polymer microcapsules of the present invention includes ethylene vinyl acetate copolymer, ethylene saponified vinyl copolymer partially saponified product, ethylene acrylic acid copolymer, ethylene acrylic And acid ester copolymers. Particularly, the melt index (MI) is 50 or more and the molecular weight is 10.
It is preferably from 000 to 100.000.
If the MI is less than 50, the dispersion stability of the microcapsules may be lacking, which is not preferable. In addition, the molecular weight is 1
If it is less than 0.000, the produced polymer microcapsules may aggregate and fuse with each other, which is not preferable.
When the molecular weight is 100.000 or more, the heat solubility of the ethylene copolymer in a non-aqueous solvent may deteriorate,
Not preferred.

As the fine particles used as the core material of the microcapsules in the present invention, known pigments used in inks, paints, toners for electrophotography, etc. and various ceramic fine particles usable as functional materials can be used. . These core materials may be used after pretreatment such as adsorption of a dispersant or a surfactant or flushing treatment with a resin.

The non-aqueous solvent used in the present invention includes linear or branched aliphatic hydrocarbons, aromatic hydrocarbons, and linear or branched aliphatic alcohols having 10 or less carbon atoms. As a specific example of the aliphatic hydrocarbon, carbon number 6 to
There are 12 straight-chain or branched-chain aliphatic hydrocarbons, Isopar (a product of Exxon Chemical Co., Ltd.) which is a mixture of aliphatic hydrocarbons having different carbon numbers, and the like. Specific examples of the aromatic hydrocarbon include benzene, toluene, xylene, ethylbenzene and the like.

[0024]

According to the method for producing polymer microcapsules of the present invention, the formation of polymer microcapsules having a sharp particle size distribution and an arbitrary particle size in the range of 0.1 to 50 μm is reproducible. Can do well.
In addition, it is easier to control the formation conditions of the polymer microcapsules than in the polymerization method, and since the surface is not contaminated by impurities such as a dispersing agent and a polymerization initiator unlike the polymer microcapsules formed by the polymerization method, Processing can be performed easily.

Further, since the polymer microcapsules are formed in a non-aqueous solvent, the formed polymer microcapsules can be easily dispersed in the organic solvent in the vehicle of the ink or paint.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing the particle size distribution of a polymer microcapsule according to a first embodiment of the method for producing a polymer microcapsule of the present invention.

FIG. 2 is an explanatory diagram showing a particle size distribution of a polymer microcapsule of a comparative example of the first embodiment.

FIG. 3 is an explanatory view showing a particle size distribution of a polymer microcapsule according to a second embodiment of the manufacturing method.

FIG. 4 is an explanatory diagram showing a particle size distribution of a polymer microcapsule according to a fourth embodiment of the manufacturing method.

FIG. 5 is an explanatory diagram showing a particle size distribution of a polymer microcapsule of a comparative example of the fourth embodiment.

FIG. 6 is an explanatory diagram showing a particle size distribution of a polymer microcapsule according to a fifth embodiment of the manufacturing method.

FIG. 7 is an explanatory diagram showing a particle size distribution of a polymer microcapsule of a comparative example of the fifth embodiment.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-2-261535 (JP, A) JP-A-62-257644 (JP, A) JP-A-58-240 (JP, A) JP-A-7-57 51560 (JP, A) JP-A-47-11659 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) B01J 13/04 C08L 29/04 C08L 31/04 C08L 101/00 G03G 9/12

Claims (6)

(57) [Claims] 1. A method in which fine particles are dispersed in a non-aqueous solvent and mixed by heating. A liquid in which an ethylene copolymer is dissolved in a non-aqueous solvent by heating is added to the dispersion, and the liquid after the addition is added. Is further mixed and dispersed by heating to a temperature equal to or higher than the melting temperature of the ethylene copolymer, and then cooled to precipitate. 2. An ethylene-vinyl acetate copolymer and a partially saponified ethylene-vinyl acetate copolymer which are hardly soluble or insoluble in a non-aqueous solvent at room temperature and which are dissolved in a non-aqueous solvent by heating. 2. The method for producing a polymer microcapsule according to claim 1, wherein at least one selected from the group consisting of an ethylene acrylic acid copolymer and an ethylene acrylic acid ester copolymer is used. 3. A fine particle such as a pigment or a ceramic is dispersed in a non-aqueous solvent and mixed by heating. In this dispersion, an ethylene copolymer for coating the fine particle on a non-aqueous solvent is previously heated and dissolved. The liquid was added, and the liquid after the addition was further mixed and dispersed by heating to a temperature equal to or higher than the melting temperature of the ethylene copolymer,
Thereafter, it is cooled to precipitate the polymer microcapsules. 4. The method for producing a polymer microcapsule according to claim 3, wherein the particle diameter is controlled by changing a solubility parameter of the non-aqueous solvent. 5. A single or a mixture of two or more of linear or branched aliphatic hydrocarbons, aromatic hydrocarbons and linear or branched aliphatic alcohols having 10 or less carbon atoms as the non-aqueous solvent. 5. The method for producing a polymer microcapsule according to claim 3, wherein 6. The ethylene copolymer having a melt index of 50 or more and a molecular weight of 10,000 or more.
2,000 or less, which is hardly soluble or insoluble at room temperature in the non-aqueous solvent and which is dissolved in the non-aqueous solvent by heating, ethylene-vinyl acetate copolymer, partially saponified ethylene-vinyl acetate copolymer, ethylene acrylic acid 6. The method for producing a polymer microcapsule according to claim 3, wherein at least one of a copolymer and an ethylene acrylate copolymer is used.