JP2877284B2 - Polymer fine particle production method - 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 a coloring material, for example, fine polymer particles for a liquid developer for electrostatography , cosmetics, additives or a filler.

[0002]

2. Description of the Related Art Conventional methods for producing polymer fine particles mainly include a pulverization method and a polymerization method.

[0003]

In the pulverization method, the resin is mechanically pulverized, so that the particle size distribution is widened, the yield of fine particles having a desired particle size is low, and the shapes of the particles are not uniform. Several μ
In order to obtain particles of m or less, a large grinding energy is required, and the yield is further reduced. Therefore, several μm
It is difficult to produce polymer fine particles having a particle size of m or less with high yield, and it is practically impossible to produce polymer fine particles having a particle size of 1 μm or less.

There is an example in which polymer particles having a uniform particle size are produced by a polymerization method, but it is difficult to control polymerization conditions. Further, it is difficult to uniformly and stably disperse fine particles polymerized in an aqueous system as primary particles in a vehicle such as an ink or a paint or in a non-aqueous solvent as in the case of a liquid developer for electrophotography. Furthermore, in both the cases of aqueous and non-aqueous polymerization, dispersants, surfactants, polymerization initiators used during polymerization,
It is inevitable that unreacted monomers and the like adhere to the particle surface, and when fine particles produced by a polymerization method are used as various functional materials, it is essential to remove and purify impurities on the surface of the particles. Indeed, purification becomes difficult.

There is disclosed a method in which an olefin resin having a carboxyl group or an ester group is heated and dissolved in a solvent having high temperature dependency in solubility for the resin, and then cooled to solidify the resin into fine particles. (Tokuhei 4
No. 13707), there is no analysis on the solubility parameter of the solvent (hereinafter referred to as SP value), and nothing is described about the control method of the diameter of the precipitated particles.

The present invention has been made in view of the above-mentioned state of the art, and an object of the present invention is to provide a method for producing polymer fine particles which are extremely fine and have a uniform particle size distribution.

[0007]

The present invention provides (1) a method of dissolving an olefin resin having a carboxyl group or an ester group in a non-aqueous solvent, and then reducing the solubility of the resin in the solvent to precipitate resin fine particles. In the above, after blending the solvent composition such that the solubility parameter of the non-aqueous solvent is close to the solubility parameter of the resin and a value at which the resin precipitates at a temperature lower than the softening point of the resin, the solubility of the resin in the solvent is reduced. A method for producing polymer fine particles, comprising precipitating resin particles. (2) The method according to (1) above, wherein polymer particles having an arbitrary particle size in the range of 0.1 to 50 μm are produced by controlling the difference between the solubility parameter of the resin and the solubility parameter of the non-aqueous solvent. A method for producing polymer fine particles. (3) The above (1) or (2), wherein the solubility of the resin in the solvent is reduced to remove polymer fine particles by removing a good solvent component for the resin in the non-aqueous solvent in which the resin is dissolved. A method for producing the polymer fine particles according to the above. (4) The above (1) or (2), wherein a poor solvent for the resin is added to the non-aqueous solvent in which the resin is dissolved to lower the solubility of the resin in the solvent to precipitate polymer fine particles. A method for producing the polymer fine particles according to the above. (5) The polymer fine particles according to (1) or (2), wherein the non-aqueous solvent in which the resin is dissolved is cooled to lower the solubility of the resin in the solvent to precipitate polymer fine particles. Production method. (6) Any of the above (1) to (5), wherein colored polymer fine particles are produced by using a resin colored with a pigment or a dye, or by adding a pigment or a dye before the resin is precipitated. 3. The method for producing polymer fine particles according to 1.). (7) The production of polymer fine particles according to any one of the above (1) to (5), wherein the resin is precipitated after adding a surfactant, a dispersant and other common additives before the resin is precipitated. Method. It is.

The resin used in the present invention is an olefin resin having a carboxyl group or an ester group, such as an ethylene / vinyl acetate copolymer or ethylene / vinyl acetate copolymer.
Partially saponified vinyl acetate copolymer, ethylene / (meth) acrylic acid copolymer, ethylene / (meth) acrylic ester copolymer, (meth) acrylic ester resin, styrene / (meth) acrylic acid copolymer And a styrene / (meth) acrylate copolymer. One of these may be used alone, or two or more of them may be used as a mixture.

The resin may be colored with a coloring material such as a pigment and / or a dye, and more specifically, a coloring material is added to the resin in advance by means of heating and kneading.
Alternatively , means such as adding a colorant before resin deposition during the production process of the present invention may be employed.

The non-aqueous solvent used in the present invention may be a single solvent or a mixed solvent. Examples of the solvent used include straight-chain aliphatic hydrocarbons, branched-chain aliphatic hydrocarbons, halogenated aliphatic hydrocarbons, aromatic hydrocarbons, and straight-chain or branched-chain aliphatic alcohols having 12 or less total carbon atoms. Or a mixed solvent of two or more as required.

[0011]

According to the present invention, an olefin resin having a carboxyl group or an ester group can be used in an amount of 0.1 to 50 μm.
In order to produce fine particles of any particle size, the resin SP
The solubility of the resin in the solvent may be reduced to precipitate the resin in the form of fine particles while controlling the difference between the SP value of the solvent and the SP value of the solvent . This will be described in detail below.

(1) The SP value of the solvent is the SP value of the resin.
And the solvent component is determined so that the resin is precipitated at a temperature lower than the softening point Ts of the resin. The precipitation particle size is determined by the difference ΔSP between the SP value of the solvent and the SP value ′ of the resin at this time. The smaller the ΔSP, the smaller the particle size. FIG.
As shown in the curve of "SP value of solvent vs. precipitated particle size",
When looking at the SP value of the resin at the center, it is not necessarily symmetrical. However, whether the SP value of the solvent is set to be higher or lower than the SP value of the resin is determined by the following operation. What is necessary is just to set to the side which is easy to control. FIG. 1 and FIG. 2 described later are examples in which the SP value of the solvent is set to a lower side than the SP value ′ of the resin. Solvent SP value of resin SP
Of course, it may be set to the exact same value as the value '.

(2) The resin is dissolved in the solvent set to the SP value. At this time, the amount of resin to be dissolved is the softening point Ts of the resin.
Following or equal to a slightly lesser extent than the solubility S ₁ at any temperature T ₁ (the (a) see FIG. 2).

(3) FIGS. 1 and 2 show examples in which the solubility of a resin is reduced by changing the SP value of a solvent from → to → to precipitate polymer fine particles. When the precipitation starts at the SP value of the solvent and the polymer particles are precipitated at the SP value of the solvent, as shown in FIG. 1, the polymer particles having a particle size distribution of 0.2 to 1.0 μm are deposited. I do. The particle size and particle size distribution at which the particle size frequency peaks are determined by the temperature T of the solvent.
_{1. It} may be controlled by changing the SP value of the solvent, the stirring speed of the solvent, and the like. When the initial SP value of the solvent is set to a higher value than the SP value of the resin, the solubility of the solvent in the resin may be reduced to precipitate the resin by changing the SP value of the solvent to a higher value.

(4) As a method for lowering the solubility of the solvent in the resin, it is preferable to change the SP value of the solvent as described in the above item (3). A method of lowering the solubility by further lowering the temperature T ₁ of the solvent may be used.

[0016]

(Example 1) In a vessel equipped with a stirrer, a thermometer, a reflux condenser, and a vacuum deaerator, 72 parts of a branched-chain aliphatic hydrocarbon Isopar G (manufactured by Esso Oil Co., Ltd.), an aromatic hydrocarbon Toluene (manufactured by Katayama Chemical Co., Ltd.): 48 parts, and aliphatic alcohol ethanol (manufactured by Katayama Chemical Co., Ltd.): 30 parts were added, and the SP value was 9.
18 non-aqueous solvents. In this, partially saponified product of ethylene / vinyl acetate copolymer Dumilan C-2280
(Takeda Pharmaceutical Co. SP value 8.93): Add 2 parts and add 75
After stirring at ℃ to completely dissolve Dumilan, keeping the temperature of the solvent at 40 ° C, which is lower than the softening point of Dumilan C-2280 78 ° C (at this time, Dumilan is in a dissolved state)
The inside of the vessel was degassed under vacuum, and toluene and ethanol were removed from the solvent to precipitate polymer fine particles.
The polymer microparticles obtained in this manner have a volume-based
The 0% particle size was 1.0 μm.

(Example 2) In Example 1, 60 parts of Isopar G was used instead of 72 parts, 40 parts of toluene was used instead of 48 parts, and 50 parts of ethanol were used instead of 30 parts. Except for using a non-aqueous solvent, polymer particles were precipitated in the same manner. The resulting particles had a 50% particle size by volume of 2.4 μm.

Example 3 Polymer fine particles were precipitated in the same manner as in Example 1, except that 50 parts of ethanol was added instead of degassing the inside of the vessel. The resulting particles had a 50% particle size by volume of 1.1 μm.

Example 4 Polymer fine particles were precipitated in the same manner as in Example 1, except that the temperature of the solvent was further reduced instead of degassing the inside of the vessel. 38 particles
At 50 ° C., the resulting particles had a 50% volume-based particle size of 1.0 μm.

(Example 5) In Example 1, a partially saponified product of ethylene / vinyl acetate copolymer, Dumiran C-2280, was replaced with an ethylene / vinyl acetate copolymer Evaflex 220 (Mitsui Co., Ltd.).
DuPont SP value 8.65 ): Polymer fine particles were precipitated in the same manner except that 2 parts were added. The obtained polymer fine particles had a volume-based 50% particle size of 1.3 μm.

Example 6 In Example 2, an ethylene-ethyl acrylate copolymer EVAFLEX-EEA was used in place of the partially saponified product of ethylene / vinyl acetate copolymer, dumilan C-2280.
A-704 ( SP value: 8.7, manufactured by DuPont Mitsui)
0 ): Polymer fine particles were precipitated in the same manner except that 2 parts were added. The obtained polymer particles are 50% by volume.
The particle size was 1.5 μm.

Example 7 In Example 1, an ethylene / methacrylic acid copolymer Nucrel 599 ((Mitsui Co., Ltd.) was used in place of the partially saponified product of ethylene / vinyl acetate copolymer Dumilan C-2280.
DuPont SP value 8.95 ): Polymer fine particles were precipitated in the same manner except that 2 parts were added. The obtained polymer fine particles had a 50% particle size based on volume of 1.0 μm.

Example 8 In Example 1, a partially saponified ethylene-vinyl acetate copolymer, dumilan C-1550 (manufactured by Takeda Pharmaceutical Co., Ltd., SP value: 8.84) was used in place of dumilan C-2280: 2 In the same manner as above except that a part was added, polymer fine particles having a volume-based 50% particle size of 0.41 μm were obtained.

Example 9 In a vessel equipped with a stirrer, a thermometer, a reflux condenser, and a vacuum deaerator, a branched-chain aliphatic hydrocarbon Isopar G: 216
Parts, aromatic hydrocarbon toluene: 144 parts and aliphatic alcohol ethanol: 90 parts were added to obtain a non-aqueous solvent having an SP value of 9.18. In this, a partially saponified product of ethylene / vinyl acetate copolymer Dumilan C-1550: 6 parts,
Coloring material Phthalocyanine Blue No. 1 (manufactured by Dainichi Seika Co., Ltd.): After adding 1.2 parts and stirring at 75 ° C. to completely dissolve Dumilan, the softening point of Dumilan C-1550 was 5
While keeping the temperature of the solvent at 40 ° C. lower than 0 ° C. (at this time, Dumilan is in a dissolved state), the inside of the vessel is degassed under vacuum,
By removing toluene and ethanol from the solvent, colored blue polymer fine particles were precipitated. The obtained polymer fine particles had a volume-based 50% particle size of 1.9 μm.

Example 10 In Example 9 , 6 parts of Dumilan C-2280 was used instead of Dumilan C-1550, and Carmine 1480 (manufactured by Dainichi Seika) was used instead of Phthalocyanine Blue No. 1
A colored (red) polymer particle dispersion having a 50% volume-based particle diameter of 3.6 μm was obtained in the same manner except that 1.2 parts was added. The mixed solvent in the polymer fine particle dispersion was replaced with Isopar G, and ordinary additives such as a charge-imparting agent were 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 commercially available coated paper.
%, An image excellent in the resolution of 0.01 D of background contamination was obtained. Note that a Macbeth densitometer was used for the measurement of density and background contamination. The transfer rate was calculated by the following equation. Transfer rate (%) = ｛ 1- ( toner concentration on photosensitive surface after transfer / toner concentration on photosensitive surface before transfer) ｝ × 100

Example 11 In a vessel equipped with a stirrer, thermometer, reflux condenser and vacuum deaerator, 198 parts of branched-chain aliphatic hydrocarbon Isopar G, 132 parts of aromatic hydrocarbon toluene, 132 parts of aliphatic Alcohol Ethanol: 120
Was added to obtain a non-aqueous solvent having an SP value of 9.54. To this, 6 parts of Dumilan C-2280 and 1.2 parts of coloring agent Benzidine Yellow H7055 (manufactured by Dainichi Seika) were added, and the mixture was stirred at 75 ° C. to completely dissolve Dumilan C-2280. While maintaining the temperature of the solvent at 40 ° C., which is lower than the softening point of 78 ° C., the container is evacuated to vacuum, and toluene,
The colored polymer fine particles were precipitated by removing ethanol from the solvent. The obtained polymer fine particles had a 50% particle size by volume of 2.4 μm.

(Example 12) In Example 10, when adding Dumilan C-2280, the surfactant Suban 8 was used.
5 (Sorbitan trioliate): A colored (red) polymer particle dispersion having a 50% volume-based particle size of 2.0 μm was obtained in the same manner except that 2 parts were simultaneously added.

[0028]

According to the present invention, the following effects can be obtained. Compared to the pulverization method, the particle size and shape are uniform and uniform particles are obtained.
It is possible to produce polymer fine particles having a size of μm or less with good reproducibility. Fine particle generation conditions are easier to control than polymerization method
In addition, the post-treatment is easy because the surface of the polymer fine particles produced as in the polymerization method is not contaminated by impurities such as a dispersant and a polymerization initiator. Since the polymer fine particles are generated in a non-aqueous system, it has an effect that the generated fine particles can be easily dispersed in a vehicle of an ink or a paint or an organic solvent.

[Brief description of the drawings]

FIG. 1 is a chart showing the relationship between the SP value of a solvent and the precipitated particle size in the present invention.

FIG. 2 is a table showing the relationship between the SP value of a solvent and the solubility of a resin in the present invention.

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-1-118505 (JP, A) JP-A-63-284226 (JP, A) JP-A-49-5438 (JP, A) (58) Field (Int.Cl. ⁶ , DB name) C08J 3/14 C08L 29/04

Claims (7)

(57) [Claims] 1. A method for dissolving an olefin resin having a carboxyl group or an ester group in a non-aqueous solvent, and then reducing the solubility of the resin in the solvent to precipitate fine particles of the resin, wherein the solubility parameter of the non-aqueous solvent is After blending the solvent composition so that the resin is precipitated at a temperature close to the solubility parameter of the resin and lower than the softening point of the resin, the solubility of the resin in the solvent is lowered to precipitate the resin particles. A method for producing polymer fine particles. 2. A method for controlling a difference between a solubility parameter of a resin and a solubility parameter of a non-aqueous solvent, thereby controlling the difference between 0.1 and 5
The method for producing polymer fine particles according to claim 1, wherein polymer fine particles having an arbitrary particle size in a range of 0 µm are produced. 3. The method according to claim 1, wherein a good solvent component for the resin in the non-aqueous solvent in which the resin is dissolved is removed to lower the solubility of the resin in the solvent to precipitate polymer fine particles. 3. The method for producing polymer fine particles according to 1 or 2. 4. A non-aqueous solvent in which a resin is dissolved,
The method for producing polymer fine particles according to claim 1 or 2, wherein the solubility of the resin in the solvent is reduced by adding a poor solvent to the resin to precipitate the polymer fine particles. 5. The process for producing polymer fine particles according to claim 1, wherein the non-aqueous solvent in which the resin is dissolved is cooled to lower the solubility of the resin in the solvent to precipitate polymer fine particles. Method. 6. The method according to claim 1, wherein the colored polymer fine particles are produced by using a resin colored by a pigment or a dye, or by adding a pigment or a dye before the precipitation of the resin. A method for producing the polymer fine particles according to the above. 7. The method for producing polymer fine particles according to claim 1, wherein the resin is precipitated after adding a surfactant, a dispersant and other common additives before the precipitation of the resin. .