JPH065394B2 - Electrophotographic developer - Google Patents

Description

TECHNICAL FIELD The present invention relates to a liquid developer for electrophotography, and more particularly to a toner for color copying. The present invention can also be applied as a coating material, a printing ink, and a dispersion polymer for magnetic materials.

2. Description of the Related Art Conventionally known polymerizable monomers having a polar group include acrylic acid, methacrylic acid, itaconic acid, fumaric acid, hydroxyethyl methacrylate, glycidyl methacrylate and the like. In these polymers or copolymers, the polar group undergoes ionic dissociation in a water solvent to improve the dispersion stability of the pigment, but the electrophotographic liquid developer (isoparaffin)
Among them, ion dissociation did not occur, and the charge of the polymer was low, so that it was difficult to control the charge to the color pigment particles. in this case,
Generally, a method such as ionizing a carboxyl group with a basic substance is used, but in this case, it was difficult to balance the acid and base, and it was impossible to use for a long period of time. Many toner particles have a particle size distribution of 0.3 to 1.0 .mu.m, and there is a demand for color toners having a smaller particle size and a narrow particle size distribution.

OBJECT The object of the present invention is to provide a liquid developer in which, in a color toner, an organic pigment is finely dispersed in order to improve color reproducibility and charge control to toner particles, fixing property, glossiness and storage stability are excellent. Is to provide.

Structure The present invention is a liquid developer for electrophotography, wherein the resin is of the general formula (I) (Wherein R is —H or —CH ₃ , X is —COOCnH _{2n + 1} or —O—CO—CnH _{2n + 1} , and n is an integer of 6 to 20) and a general formula (II) (Wherein R ₁ is -H or -CH ₃ , N is an integer of 1 to 20, and R ₂ is -H, Na, K, Mg, Mn, Ca, Li, A or Co). A liquid developer for electrophotography which uses a resin obtained by polymerizing a system containing at least the monomer B.

To prepare the liquid developer of the present invention, generally, 0.3 part by weight of the copolymer is mixed with 1 part by weight of the colorant, and the mixture is mixed with 10-20 parts by weight of the petroleum-based aliphatic hydrocarbon in an attritor. Thoroughly disperse with a Keddy mill or the like to obtain a concentrated toner.

Examples of the colorant for color include benzidine-based organic pigments, phthalocyanine-based organic pigments, thioindigo-based organic pigments, methyl orange, brilliant carmine, alkali blue, fare-stred, crystal violet and chromophorin-red.

Of course, carbon black can also be used as the coloring agent. A polar control agent or the like may be added if necessary.

Petroleum-based aliphatic hydrocarbons or halogenated aliphatic hydrocarbons such as kerosene, ligroin, n-hexane, n-heptane, n-octane, i-octane, and i are used as a solvent for producing the liquid developer of the present invention. -Dodecane (exon's Isopar H, G, L, K; naphtha
NO.6; Solvetso 100 and the like), carbon tetrachloride, perfluoroethylene and the like. A small amount of an aromatic solvent such as toluene or xylene can be added to these aliphatic solvents.

As the polymerization catalyst used for producing the resin of the present invention, a usual radical polymerization catalyst can be used, and specifically, benzoyl peroxide, di-t-butyl peroxide, dicumyl peroxide, methyl ethyl ketone peroxide, t -Butyl perphthalate, t-butyl perbenzoate, methyl isobutyl ketone peroxide,
Organic peroxides such as lauroyl peroxide, cyclohexyl peroxide, 2,5-dimethyl-2,5-di-t-butylperoxyhexane, t-butylperoctanoate, t-butylperisobutyrate and t-butylperoxyisopropylcarbonate. Oxides and methyl-2,2 '
-Azobisisobutyrate, 1,1'-azobiscyclohexanecarbonitrile, 2-phenylazo-2,4-dimethyl-4-methoxyvaleronitrile, 2-carbomoyl-azobisisobutyronitrile, 2,2'- Examples thereof include azo compounds such as azobis- (2,4-dimethylvaleronitrile) and 2,2'-azobisisobutyronitrile.
The amount of the polymerization catalyst used is about 0.1 to 2.0 based on the total weight of the monomers.
% By weight.

Specific examples of the monomer A used for producing the resin of the present invention include lauryl methacrylate, lauryl acrylate, stearyl methacrylate, stearyl acrylate, 2-ethylhexyl methacrylate, 2-ethylhexyl acrylate, dodecyl methacrylate, dodecyl acrylate, hexyl methacrylate and hexyl. Acrylate, octyl methacrylate, octyl acrylate, cetyl methacrylate, cetyl acrylate,
Examples include vinyl laurate and vinyl stearate.

The following are specific examples of the monomer B used in the production of the resin of the present invention.

NO.1. NO.2. NO.3. NO.4. NO.5. NO.6. NO.7. NO.8. NO.9. NO.10. NO.11. NO.12. NO.13. NO.14. NO.15. NO.16. NO.17. NO.18. NO.19. On the other hand, the monomer A has a property of being solvated with the solvent before and after the polymerization. Accordingly, the copolymer thus obtained has a monomer B component as a center in a solvent, and a monomer A component solvated with the solvent is dispersed around the monomer B component. Here, the monomer A component in the copolymer contributes to improvement of toner dispersion stability (thus storage stability) and adhesiveness. The ratio of monomer B to monomer A is 0.01-
About 1: 1 (weight) is suitable. Further, other polymerizable monomer (hereinafter referred to as monomer C) can be added to these monomer A and monomer B components. Further, it is suitable that the ratio of the monomer C to the monomer A is 0.01 to 1: 1 (weight).

Monomer B is an organic polar monomer having (-CH ₂ · CH _2- ) n, which does not dissolve well in an aqueous solution like acrylic acid and has a property of being solvated in a non-aqueous solvent. There is. Therefore, it can be considered that the organic polar polymer having a carboxyl group in the copolymerization with the long-chain acrylic ester produces an appropriate carboxylate anion and induces the charge generation of the polymer.

In the present invention, a non-aqueous solvent can be prepared by a known method such as a soluble polymer, a partially gelled semi-dissolved polymer, a particulate polymer or an insoluble polymer.

Examples of the monomer C include styrene, vinyltoluene, vinyl acetate, an alkyl (C 1-5) ester of acrylic acid or methacrylic acid (for example, methyl methacrylate,
Ethyl acrylate, methyl acrylate, ethyl methacrylate, butyl methacrylate), polyhydric alcohol di (meth) acrylate (for example, ethylene glycol diacrylate, ethylene glycol dimethacrylate,
Diethylene glycol diacrylate, diethylene glycol methacrylate, triethylene glycol triacrylate, triethylene glycol trimethacrylate, butanediol diacrylate, butanediol dimethacrylate, 1,6-hexanediol diacrylate, 1,6-hexanediol dimethacrylate, trimethylolpropane Triacrylate, trimethylolpropane trimethacrylate, tetramethylolmethane triacrylate, tetramethylolmethane trimethacrylate, tetramethylolmethane tetraacrylate,
Tetramethylol methane tetramethacrylate, dipropylene glycol diacrylate, dipropylene glycol dimethacrylate, trimethylol hexane triacrylate, trimethylol hexane trimethacrylate, pentaerythritto tetraacrylate, pentaerythritto tetramethacrylate, 1,3-butylene glycol diacrylate , 1,3-butylene glycol dimethacrylate, trimethylolethane triacrylate, trimethylolethane methacrylate, allyl methacrylate, methallyl methacrylate, etc., o-divinylbenzene, m-divinylbenzene, p-divinylbenzene, p-methyldivinylbenzene, o-ethyldivinylbenzene, o-butyldivinylbenzene, p-butyldivinylbenzene, m -Hexyldivinylbenzene, o
-Nonyldivinylbenzene, p-decyldivinylbenzene, o-undecyldivinylbenzene, p-stearyldivinylbenzene, o-methyldivinylbenzene, o-
Examples thereof include ethyldivinylbenzene, p-hexyldivinylbenzene, p-nonyldivinylbenzene, m-decyldivinylbenzene, p-undecyldivinylbenzene, o-stearyldivinylbenzene and vinyltoluene.

In the present invention, silica fine particles and softening point are used in the copolymer production process.
Wax or polyolefin at about 60 to 130 ° C can be added. When the silica fine particles are used, the copolymer is considered to be obtained in a state where the silica fine particles are incorporated in the network structure. The silica itself does not undergo physical changes such as dissolution during the reaction. In any case, in the case of silica, the specific gravity is similar to that of the aliphatic hydrocarbon or halogenated aliphatic hydrocarbon solvent which is the dispersion medium, and the gelation of the copolymer is prevented, which helps improve the dispersion stability of the toner. . On the other hand, when wax or polyolefin is used, the product is dissolved in the reaction system during the polymerization reaction, and after the reaction, it is deposited in the form of fine particles in this system by cooling. Thus, it is considered that the copolymer can be obtained in the state of being adsorbed on or mixed with wax or polyolefin fine particles. Here, wax or polyolefin, similar to silica, has a specific gravity close to that of the dispersion medium and prevents gelation of the copolymer.
Since the molecular structure is similar to that of the dispersion medium, it is useful not only for improving the dispersion stability of the toner, but also for improving the adhesiveness (fixability) because of its low softening point. The amount of silica, wax or polyolefin added is appropriately about 5 to 50 parts by weight per 100 parts by weight of the copolymer.

Specific examples of commercially available wax or polyolefin having a softening point of 60 to 130 ° C. are as follows.

The production examples and examples of the copolymer are shown below.

Production Example 1 300 g of isooctane was placed in a 2.0 four-necked flask equipped with a stirrer, a thermometer and a reflux condenser, and heated to 90 ° C. 190 g of dodecyl methacrylate, o-
Butyldivinylbenzene 10g, Monomer B, NO.4,
After a solution consisting of 20 g and 6 g of azobisisobutyronitrile was added dropwise over 3 hours, the mixture was heated and stirred at the above temperature for 4 hours to carry out a polymerization reaction, and a polymerization rate was 95.0% and a viscosity was increased.
A resin solution of 210 cp was obtained.

Production Example 2 300 g of the resin dispersion obtained in Production Example 1 was mixed with 10 g of colloidal silica in a flask, heated at 100 ° C. for 3 hours and cooled to have a viscosity of 220 cp and a particle size of 0.3 to 0.1. A 4μ colloidal silica-containing resin dispersion was obtained.

Production Example 3 300 g of isododecane was placed in the same flask as in Production Example 1,
Heat to 90 ° C. Then, a solution containing 300 g of lauryl methacrylate, 25 g of monomer B, NO.1, 25 g of allyl methacrylate and 3 g of benzoyl peroxide was added dropwise thereto over 1.5 hours, and the solution was further added at 95 ° C for 4 hours.
Polymerization reaction was carried out by heating and stirring for a period of time to obtain a resin liquid having a polymerization rate of 96.5% and a viscosity of 180 cp. Next, vinyltoluene 50
g and 1 g of benzoyl peroxide were added dropwise to the resin solution at 90 ° C., and polymerization was carried out for 4 hours. The polymerization rate was 97.2% and the polymer had a negative charge.

The polymer charge was measured as follows.

Place 3% by weight of polymer dispersion in kerosene in a 100 m beaker for 25 m, and set an electrode interval of 10 mm to 20 mm x 40.
An applied voltage of 1000 V is applied between the mm copper electrodes.

In the judgment, a polymer having electrodeposited on the positive electrode was a negatively charged polymer, and a polymer having electrodeposited on the negative electrode was a positively charged polymer.

Production Example 4 300 g of the resin dispersion obtained in Production Example 3 was mixed with 20 g of densified beeswax in a flask, stirred at 90 ° C. for 2 hours, and then cooled to have a viscosity of 580 cp and a particle size of 0.1 to 1. 0 μ of resin dispersion was obtained. The polymer had a negative charge.

Production Example 5 Sanwax 171-P300 was placed in the same flask as in Production Example 1.
g was taken and heated to 90 ° C. 150 g of 2-ethylhexyl methacrylate, Monomer B, NO.15,
A solution of 30 g, 20 g of p-divinylbenzene and 6.3 g of lauroyl peroxide was added dropwise over 3 hours, and the mixture was further stirred at the above temperature for 4 hours to carry out a polymerization reaction, with a polymerization rate of 98.2% and a viscosity of 690 cp. , Particle size 0.1-3.0μ
A resin dispersion of was obtained. The polymer had a positive charge.

Production Example 6 300 g of Isopar L and 60 g of polyethylene (AC-6 manufactured by Allied Chemical Co.) were placed in the same flask as in Production Example 1 and heated to 95 ° C. Next, a solution of 180 g of stearyl methacrylate, monomer B, NO.11, 20 g, 20 g of allyl methacrylate and 4 g of lauryl peroxide was added dropwise thereto over 3 hours, and the mixture was stirred at the above temperature for 3 hours to carry out the polymerization reaction. Conducted, polymerization rate 95.4%
Thus, a resin dispersion having a viscosity of 200 cp and a particle size of 0.8 to 2.2 μm was obtained. The polymer had a negative charge.

Production Example 7 Isopar H 300 g, cetyl methacrylate 180 g, dodecyl acrylate 40 in the same flask as in Production Example 1.
g, methallyl methacrylate 15 g, monomers B, N
O. 19, 30 g and 3 g of benzoyl peroxide were taken, and a polymerization reaction was carried out at 90 ° C. for 6 hours to obtain a resin dispersion liquid having a polymerization rate of 98% and a viscosity of 240 cp and a particle size of 1 to 3 μm. The polymer had a positive charge.

Example 1 Benzidine yellow (manufactured by Dainichiseika Co., Ltd.) 20 g The polymer 60 kerosene 150 obtained in Production Example 1 was dispersed for 3 hours with an attritor to give a concentrated toner. The particle size of the obtained toner was 0.21 to 0.33 μm.

Example 2 20 g of phthalocyanine (manufactured by Toyo Ink Co., Ltd.) The polymer 80 Isopar G 150 of Production Example 2 was dispersed in a ball mill for 24 hours to obtain a concentrated toner. The particle size of the obtained toner was 0.08 to 0.23 μm.

Example 3 Brilliant carmine (manufactured by Dainippon Ink) 20 g Polymer 80 Isopar H 150 of Production Example 3 was dispersed in an attritor for 3 hours to give a particle size of 0.04 to 0.21 μm.
Toner was obtained.

Example 4 Phthalocyanine green (manufactured by Dainippon Ink) 20 g Polymer 80 kerosene 150 of Example 4 was dispersed in an attritor for 3 hours to give a particle size of 0.05 to 0.15 μm.
I got that.

Example 5 Crystal Violet (manufactured by Tokyo Kasei) 10 g Polymer 80 of Production Example 5 Isopar H 150 Manganese naphthenate 1 Dispersed in a ball mill for 48 hours to obtain a toner having a particle diameter of 0.10 to 0.20 μm.

Example 6 Carbon black Mitsubishi # 44 10 g (manufactured by Mitsubishi Carbon Co., Ltd.) The polymer 80 of Production Example 6 was dispersed for 12 hours with Isopar G 150 Kedemi Mill, and a toner having a particle diameter of 0.20 to 0.34 μ was obtained.

Example 7 Benzidine yellow (manufactured by Dainichiseika) 10 g Polymer 80 of Preparation Example 7 Isopar G 150 Dispersed with an attritor for 12 hours to give a particle size of 0.15 to 0.21 μm.
Toner was obtained. Ricoh color copier CR-1000
When copying was carried out by a usual method under (trade name), an image density of 1.18, a fixing rate of 81.5% and a glossy image were obtained.

Example 8 Mitsubishi Carbon MA100 20g Polymer 80 of Preparation Example 6 150g Isopar H 150g Dispersed for 12 hours with a Keddy mill to obtain a toner having a particle size of 0.12 to 0.20μ. When copied with Recopy DT-1800R, the image density is 1.32, the fixing rate is 83.8%, and the storability is 1
It has been stable for over a year.

Effect As is clear from the above description, the developer of the present invention makes it possible to produce a toner having a small particle size and a narrow particle size distribution.

As a result, the color toner is particularly excellent in color reproducibility. Further, general-purpose toners also have the effect of improving dispersion stability, storability, fixability, glossiness and the like.

Claims (1)

[Claims] 1. In an electrophotographic liquid developer, the resin is represented by the general formula (I). (Wherein R is —H or —CH ₃ , X is —COOCnH _{2n + 1} or —O—CO—CnH _{2n + 1} , and n is an integer of 6 to 20) and a general formula (II) (Wherein R ₁ is -H or -CH ₃ , N is an integer of 1 to 20, and R ₂ is -H, Na, K, Mg, Mn, Ca, Li, A or Co). A liquid developer for electrophotography using a resin obtained by polymerizing a system containing at least a monomer B.