JPH0124302B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a new method for producing a liquid developer for developing electrostatic latent images, and particularly provides a method for easily obtaining toner particles having excellent dispersion stability. An effective means for developing a polymer dispersion system exhibiting good dispersion stability is the use of a dispersion system using a graft polymer. For example, as described in Japanese Patent Publication No. 53-54029 and Japanese Patent Publication No. 57-12985, a vinyl group that can be polymerized by a polymer reaction is introduced into a precursor polymer in advance, and the monomer is polymerized in the presence of this vinyl group. There is a method of producing a graft copolymer. However, when polymerization is carried out by such a method, gel formation often occurs, and it may be difficult to form dispersed particles. The present invention does not utilize the above-mentioned graft polymerization method, but rather shows a method for stabilizing the dispersion of an insoluble polymer through interaction between a soluble polymer and an insoluble polymer in a carrier liquid. The present invention shows a method for obtaining a polymer dispersion system having good dispersion stability without gel formation by polymerizing an insoluble polymer in the presence of the present invention. Further, the method shown in the present invention has the advantage that stable dispersed particles can be formed without using a graft polymer, and is a simple and practically advantageous method for producing dispersed particles. Therefore, the object of the present invention is to obtain a polymer dispersion system with excellent dispersion stability without using a graft polymer, and furthermore, to obtain a polymer dispersion system that is substantially insoluble in a medium and has an adsorption ability in the presence of a soluble polymer. By producing such a polymer, a stable polymer dispersion system can be obtained without gel formation. In addition, as will be described later, the purpose of this method is to control the particle size of the produced particles by adjusting the concentration of adsorption sites present in the polymer, thereby obtaining polymer particles of a desired particle size. The dispersed resin particles obtained in the present invention basically consist of a solvent-soluble polymer (hereinafter referred to as the first polymer) and a solvent-insoluble polymer (hereinafter referred to as the second polymer).
It consists of Both the solvent-soluble polymer and the solvent-insoluble polymer have relatively polar functional groups, and due to the interaction between these functional groups, the first polymer is adsorbed onto the surface of the second polymer particle, and Forms an adsorption protective layer that prevents agglomeration and fusion between particles. The polymer dispersion system shown in the present invention consists of a first polymer and a second polymer having functional groups that interact with each other.
Examples of interacting functional groups include acrylic acid, methacrylic acid, maleic anhydride, mono-2-ethylhexyl maleate, mono-n-octyl maleate, and mono-fumarate. -COOH group such as 2-ethylhexyl, mono-n-octyl fumarate, - such as vinylsulfonic acid, p-vinylbenzenesulfonic acid, etc.
Acidic groups such as SO ₃ H groups, NH ₂ groups such as vinylamine, -N(CnH ₂ n+ ₁ ) ₂ (n = 1 ~
3) groups, vinylpyridine and its derivatives, vinylimidazole and its derivatives, nitrogen-containing heterocyclic groups such as N-vinylpyrrolidone, -OCOCH ₃ - group, p-
_-NO2 groups such as vinylnitrobenzene, -CN groups such as acrylonitrile and methacrylonitrile, -OH groups such as hydroxyethyl methacrylate and hydroxypropyl acrylate, ethoxyethyl methacrylate, methoxyethyl methacrylate, methoxypolyethylene glycol, methacrylate, etc. combination with a basic group such as _-CH2 -O-C- _H2- group, or a combination of -OH group and a basic group such as _-CH2 -O- _CH2 group, _-NO2, etc. and a combination with a polar functional group. Comparisons can also be made by separately synthesizing the above first polymer and second polymer, dissolving both polymers in a common solvent for both polymers, and then dropping the above polymer solution into an imparaffin-based hydrocarbon solvent, etc. Polymer particles exhibiting good dispersion stability can be obtained, but it is often undesirable to keep a relatively large amount of the common solvent used in the dispersion system, as it may reduce the insulation properties of the system. Unless ultrasonic waves are used as a dispersion means, large amounts of aggregates may sometimes be produced. Therefore, it is extremely disadvantageous in terms of removal and dispersion of the above-mentioned common solvent from the system. On the other hand, according to the method of the present invention, in the presence of the first polymer having adsorption ability, a monomer that is soluble in the solvent used in the monomer state but becomes insoluble in the solvent when formed into a polymer is carried out. When this was carried out, no common solvent was required for both of the above-mentioned polymers, and polymer-dispersed particles having a particle size of at most 1 μm or less were always obtained as a product.
At this time, the first polymer already present in the polymerization system merely has an adsorption effect on the precipitated second polymer, and little or no grafting occurs to the first polymer. It is only the interaction between the functional groups present in the first polymer and the second polymer that protects and stabilizes the resulting polymer particles. This is clear from the fact that stable dispersed particles were not formed when neither of the two types of polymers had the above-mentioned functional groups. Furthermore, the aforementioned Tokuko Shou 53-54029 or Tokuko Sho
57-12985, gel formation was often observed when similar polymerization was carried out in the presence of a soluble polymer having a polymerizable vinyl group; When the polymerization was carried out in this manner, no grafting to the soluble polymer took place and therefore no gel formation was always observed. Furthermore, according to the polymerization method shown in the present invention, it was possible to produce emulsions with solid content concentrations as high as about 50%. The first polymer used in the present invention is, for example, a polymer that is soluble in the isoparaffinic hydrocarbon solvent used, and when it is a copolymer as an adsorption point for a solvent-insoluble polymer, the copolymer component For example, in order to impart solubility to the polymer as a copolymer component, the first polymer has the following general formula (a). X=H, _CH3 , Y= _CO2CmH2m + ₁ (6≦m≦22) _CnH2n + ₁ (2≦n≦20) _OCpH2p + _{1 (} 6≦p≦20) Particularly preferred is a carrier-liquid-soluble polymer obtained by polymerization. The supporting liquid here is an organic solvent with a low dielectric constant and high electrical insulation properties, such as normal paraffinic hydrocarbons, isoparaffinic hydrocarbons, alicyclic hydrocarbons, aromatic hydrocarbons, halogenated aliphatic hydrocarbons, etc. Examples include hydrogen, but isoparaffinic hydrocarbons are preferred, such as Siel Sol 71 (manufactured by Siel Petroleum),
Isopar G, Isopar H and Isobar K
Also, Isopar L (manufactured by Etsuo Oil Co., Ltd.), IP Solpent (manufactured by Idemitsu Oil Co., Ltd.), etc. can be used. On the other hand, the monomer that provides the second polymer that is practically insoluble in the above-mentioned supporting liquid and that constitutes the dispersed particles is basically soluble in the above-mentioned supporting liquid in the monomer state, but when it forms a polymer, it becomes soluble in the supporting liquid. Any monomer can be used as long as it has the property of decreasing solubility and causing polymer precipitation. If the monomer itself used at this time provides a polymer that has adsorption ability for the first polymer described above, it is possible to polymerize as a single monomer to provide dispersed particles, but on the other hand,
When forming a polymer that does not have adsorption ability for the first polymer with the monomer providing the above-mentioned insoluble polymer alone, a copolymer is formed using, for example, a comonomer having the following functional groups as a copolymerization component, Can provide dispersed particles. That is,
As the monomer that provides the polymer with adsorption ability for the polymer that is soluble in the carrier liquid, a monomer that has a polar functional group different from that of the soluble polymer in the combination of polar functional groups described above is selected. Further, as a monomer forming the second polymer, for example, styrene and its derivatives, C ₁ -C ₄ alkyl ester of acrylic acid or methacrylic acid, etc. can be used as a copolymerization component. It is possible to control the particle size of the resulting dispersed particles by changing the ratio of the above-mentioned functional groups present in the first polymer and the second polymer.
That is, for example, particle formation is promoted by increasing the concentration of adsorption sites in the second polymer, and as a result, the particle size tends to become smaller as the number of particles increases. Furthermore, when a relatively highly polar monomer is used as a monomer to provide the second polymer, the solubility of the resulting polymer decreases, and the number of particles formed at the initial stage of polymerization increases, resulting in a decrease in particle size. On the other hand, when forming the second polymer, if a monomer as shown in the above general formula (a) is copolymerized as a copolymerization component to increase the solubility in the supporting liquid, the particle formation rate will be delayed, and the particle formation rate will be delayed. The diameter increases. Furthermore, the particle size can also be controlled by changing the ratio of the first polymer and the second polymer. That is, as the concentration of the first polymer decreases during polymerization, the concentration of adsorption sites for the generated second polymer decreases, resulting in an increase in particle size. Utilizing the above-mentioned properties, it has become possible to control the particle diameter of dispersed particles fairly freely according to the method shown in the present invention. Conventionally, such methods for controlling particle size have been described, for example, in the reference literature ``Dispersion''.
Powmerizafion in Organic Media”edifed by
K.E.J.Barrett, John Willey and Sons,
This method overcomes the practical difficulty of using a method of protecting and stabilizing dispersed particles using a block or graft copolymer as described in London, 1974, etc. In order to use the polymer dispersion obtained according to the above description as a liquid developer for electrophotography, the dispersed particles may be colored and charged. As the coloring agent for the dispersed particles, any coloring agent generally known as a coloring agent for wet type developers can be used. For example, oil-soluble azo dyes such as Oil Black and Oil Red, basic azo dyes such as Bismarck Brown and Chrysoidine, acidic azo dyes such as Wool Black, Amid Black Green, and Blue Black HF, direct dyes such as Direct Deplac E and Congo Red, Dyes such as anthraquinone dyes such as tanbiot and acid blue, carbonium dyes such as auramine, malachite green, and crystal violet Victoria blue, rhodamine dyes such as rhodamine B, and quinoneimine dyes such as safranin, nigrosine, and methylene blue are exemplified. Examples of the pigment include carbon black, phthalocyanine blue, phthalocyanine green, washing red, and benzicine yellow. It is also possible to use surface-treated pigments such as carbon black dyed with nigrosine, kraft carbon, silicon oxide fine powder dyed with rhodamine B, and microlith blue. As for the method of coloring the dispersed polymer particles, there is a method in which the dye is previously dissolved in a solvent that dissolves the dye used, and this dye solution is added dropwise to the dispersed polymer liquid and stirred. In this case, the solvent for the dye is preferably mixed with, for example, an isoparaffinic hydrocarbon solvent used as the carrier liquid. Furthermore, it is desirable to use a solvent with relatively insulating properties and a high boiling point as a solvent for the dye. 57
As seen in No. 48738, it is possible to produce a liquid developer that can be used satisfactorily as an electrophotographic wet developer without removing the solvent for the dye. Therefore, if a dye with relatively high solubility in organic solvents is used, such as an oil-soluble dye, and the amount of solvent relative to the dye is kept small, there is no need to remove the solvent after coloring the dispersed polymer particles. It disappears. Furthermore, in the polymer dispersion system, the adsorption functional groups contained in the dispersed particles can be used as adsorption points for dyes or pigments, and by introducing relatively highly polar functional groups into the polymer, dyes or pigments can be absorbed. This increases the dyeability (adsorption capacity) for dyes or pigments, making it difficult for dyes or pigments to be desorbed from the dispersed particles after coloring. If such a functional group having the above-mentioned adsorption ability is introduced into the dispersed particles, even when a dye is used for coloring, when the dye solution is added to the dispersed polymer liquid as described above, the amount of solvent for the dye will be reduced. Even if the dye precipitates in a dispersed polymer liquid, the precipitated dye is adsorbed in molecular form to the polymer particles, and the polymer dispersed particles can be successfully colored. Therefore, the solubility of the dye during coloring becomes less important, and the amount of solvent for the dye can be extremely reduced. In the wet type developer of the present invention, by selecting a charge control agent, dye, pigment, etc., it is possible to freely produce a toner having a positive charge or a toner having a negative charge. Examples of the charge control agent used in the wet developer of the present invention include copper oleate, cobalt naphthenate, zinc naphthenate, manganese naphthenate, cobalt octylate, lecithin, sodium dioctyl sulfosuccinate, and aluminum salt of steverite rosin. can be mentioned. Furthermore, toners produced by appropriately selecting monomers according to the method described in the present invention can be used, for example, in Japanese Patent Applications No. 56-175048, No. 56-175049, No. 57 No.
-4158 and 57-4158, it is possible to provide a toner having etching resist properties when etched with an alkaline aqueous solution after development and fixation. Toner compositions used for such purposes include, for example, Japanese Patent Applications No. 57-4157, No. 57-10325, No. 57
Toner particle compositions similar to those described in JP-21829 can also be used. Example 1 1 equipped with stirrer, thermometer and nitrogen inlet tube
500 g of IP Solvent (manufactured by Idemitsu Oil Co., Ltd.) made of isoparaffinic hydrocarbon, 170 g of stearyl methacrylate, and 30 g of dimethylamino methacrylate were placed in a flask, and the mixture was heated for 75 minutes under nitrogen introduction.
Stirring was carried out for 30 minutes at °C. Then 1g of AIBN (azobisisobutyronitrile) as a polymerization initiator
was added and polymerized for 3 hours on a 75°C water bath to obtain a first polymer solution. After that, take 100g of the product solution and mix it with a stirrer.
1 with thermometer, dropping funnel and nitrogen inlet tube
Transfer to a flask and add 300g of IP Solvent.
Add the monomer methyl methacrylate 90 to give the second polymer through the dropping funnel on a 70°C water bath.
g, 10 g of maleic anhydride mono-2-ethylhexyl ester and 1 g of AIBN were added dropwise over 3 hours. Thereafter, the mixture was further heated under a nitrogen atmosphere for 3 hours, and then cooled to room temperature. The product was a white emulsion containing a composite resin dispersion with an average particle size of 1.12μ and excellent dispersion stability. Then, a solution prepared by dissolving 5 g of Oil Yellow GG-S (manufactured by Orient Chemical Co., Ltd.) in 20 g of xylene was added dropwise to this emulsion solution while stirring. Further, 1 g of aluminum stearate was added as a charge control agent, and the mixture was diluted 50 times in IP solvent to prepare a toner solution. The obtained toner was a positively charged toner exhibiting good dispersion stability. Example 2 Equipped with stirrer, thermometer, and nitrogen inlet tube
500g of IP Solvent in a 1.5 flask,
Add 100 g of lauryl methacrylate and 5 g of methacrylic acid, add 1 g of BPO (benzoyl peroxide) as a polymerization initiator, and polymerize for 5 hours on a water bath at 85°C to obtain a first polymer solution. Monomers giving the second polymer: 100 g of methyl methacrylate, 5 g of diethylamino methacrylate, and 100 g of IP Solvent.
g, AIBN 1 g was added dropwise over 2 hours and heating continued on a 75° C. water bath. then 85
After continued heating at ℃ for 3 hours, a solution of 5 g of oil yellow dissolved in 20 g of xylene and 1 g of aluminum stearate as shown in Example 1 was added.
After adding IP solvent, it was diluted 50 times. The product was a yellow emulsion with an average particle size of 0.2μ and excellent dispersion stability. Example 3 Polymerization was carried out under various conditions as shown in Table 1 below in the presence of a lauryl methacrylate-methacrylic acid copolymer solution, which is the first polymer synthesized as shown in Example 2. The results are shown in the case of aging.

[Table] Example 4 In 500 g of a 10% solution of lauryl methacrylate-methacrylic acid copolymer synthesized as shown in Example 2, 200 g of IP solvent, 100 g of styrene as a monomer to provide the second polymer, 4
- Vinylpyridine 10g, methyl methacrylate
50 g and 1.5 g of polymerization initiator AIBN were added, and the mixture was heated and stirred at 75° C. for 5 hours under a nitrogen atmosphere. The product was a stable composite resin dispersion emulsion with an average particle size of 0.20μ. Example 5 A similarly stable emulsion was formed in a system containing 1-vinyl-5-methylimidazole in place of 4-vinylpyridine in Example 4. Example 6 100 g of vinyl acetate and 1 g of AIBN were added to 500 g of a 10% lauryl methacrylate-methacrylic acid copolymer solution synthesized as shown in Example 2, and heated at 75° C. for 3 hours. The product has an average particle size
It was a 0.21μ white emulsion. Next, a solution prepared by dissolving 2 g of Victoria Blue in 50 g of methanol was added to 100 g of this emulsion solution, and the mixture was heated and stirred. The product was a blue colored stable emulsion. Example 7 Similar to Example 6, lauryl methacrylate
100 g of vinyl acetate, 20 g of dimethylaminoethyl methacrylate and 1 g of AIBN were added to 500 g of a 10% methacrylic acid copolymer solution, and the mixture was heated and stirred at 75° C. for 4 hours. The product was a stable white emulsion with an average particle size of 0.09μ. Example 8 Similar to Example 6, lauryl methacrylate
Add 100 g of vinyl acetate, 20 g of n-butyl acrylate, 10 g of dimethylaminoethyl methacrylate, 200 g of IP solvent and 1.5 g of AIBN to 500 g of a 10% solution of methacrylic acid copolymer,
Heated at ℃ for 6 hours. The product has an average particle size of 0.25μ
It was a white emulsion. Then, a solution prepared by dissolving 5 g of Oil Yellow GG-S (manufactured by Orient Chemical Co., Ltd.) in 20 g of xylene was added dropwise to this emulsion solution while stirring. Further, 1 g of ferric stearate was added as a charge control agent, and the mixture was diluted 50 times in IP solvent to prepare a wet developer for electrophotography. The obtained developer exhibited good dispersion stability and excellent fixing properties. Example 9 In 500 g of a 10% lauryl methacrylate-methacrylic acid copolymer solution synthesized as shown in Example 2, 200 g of IP solvent, 50 g of methyl methacrylate, 10 g of allylonitrile,
1 g of AIBN was added, and the mixture was heated and stirred at 80°C under nitrogen introduction. The product was an emulsion with an average particle size of 0.10μ. Example 10 100 g of stearyl methacrylate and methoxypolyethylene glycol methacrylate (

[Formula] N = 9) 10g and AIBN 1.8g were placed in a flask equipped with a stirrer, thermometer and nitrogen inlet tube, 500g of IP Solvent was added and heated at 75°C for 5 hours.
Stirring was performed. Then take 100g of the product solution,
Methyl methacrylate 50g, styrene 35g, hydroxyethyl methacrylate 10g and
1.0 g of AIBN was added and the mixture was heated and stirred at 75°C for 5 hours.
The product was a stable emulsion with an average particle size of 0.15μ. Next, 8 g of Oil Black HBB manufactured by Orient Chemical Co., Ltd. was dissolved in 60 g of xylene, and this was added dropwise to the above-produced emulsion liquid and stirred, followed by adding 1.5 g of aluminum stearate as a charge control agent.
A toner was prepared by adding IP solvent and diluting the solid content to 0.9%. When this toner is used for lithographic printing original plates such as those described in Japanese Patent Applications 175048-1980, 175049-1980, 4158-1980, and 4158-1980, etching treatment is performed with an alkaline aqueous solution after development and fixation. As a result, it could be used as a wet developer with good etching resist properties. Example 11 To 500 g of a 10% lauryl methacrylate-methacrylic acid copolymer solution synthesized as shown in Example 2, 200 g of IP Solvent, 50 g of methyl methacrylate, 50 g of styrene, 10 g of N-vinylpyrrolidone, and 1 g of AIBN were added. The mixture was heated and stirred at 75°C. The product was a stable emulsion with an average particle size of 0.12μ. Example 12 100 g of stearyl methacrylate and 1 g of p-vinylbenzenesulfonic acid were added to 500 g of IP Solvent, and after adding 1 g of AIBN, the mixture was heated and stirred at 75° C. for 3 hours. Then take 100g of the product solution and add 50g of methyl methacrylate, 5g of hydroxypropyl acrylate, 300g of IP solvent and 1.0g of BPO (benzoyl peroxide).
was added and polymerization was carried out at 85°C for 5 hours. The product was an emulsion with an average particle size of 0.09μ. Example 13 2-ethylhexyl acrylate 50g and p
- Add 100 g of IP Solvent to 5 g of nitrostyrene in the presence of 0.5 g of AIBN and heat at 75°C for 3 hours.
Stirred. After that, 30 g of styrene, 60 g of methyl methacrylate, 8 g of hydroxyethyl methacrylate and 1.5 g of BPO were added to the product solution and heated at 90℃ for 4 hours.
The mixture was heated and stirred for hours. The product was an emulsion with an average particle size of 0.30μ.

Claims (1)

[Claims] 1. In a method for producing an electrophotographic wet developer containing resin particles dispersed in a highly insulating hydrocarbon medium,
to the first polymer under conditions in which a first polymer having a polar functional group that is soluble in the medium and capable of adsorbing the second polymer is dissolved in the medium. By polymerizing monomers having polar functional groups capable of adsorption, a second polymer having low solubility in the medium is produced, which is essentially particulate; A method for producing a composite resin-dispersed electrophotographic wet developer characterized by comprising a combination of an acidic group and a basic group, or a combination of a hydroxyl group and a polar functional group capable of hydrogen bonding thereto.