JPS5952253A - Electrostatic image developing toner and its preparation - Google Patents

Abstract

PURPOSE:To obtain a toner giving superior image quality, by dissolving a specified org. titanate into a polymerizable monomer or dispersing carbon black having adsorbed this titanate at the time of dispersing carbon black into a polymerizable monomer. CONSTITUTION:Carbon black having adsorbed an org. titanate on the surface is obtained by dissolving said org. titanium compd. represented by the formula (R1 is 1-8C straight or branched alkylene, and R2 is 1-20C straight or branched alkyl) in toluene, immersing carbon black into this soln., and evaporating toluene. This carbon black is dispersed into a polymerizable monomer, and this is suspension polymerized, or the org. titanate is dissolved in the monomer, and carbon black is dispersed into the monomer, and then, suspension polymn. is carried out. As a result, and obtained toner having carbon black uniformly dispersed can give a sharp image.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a dry toner for developing electrostatic images in electrophotography, electrostatic recording, and electrostatic printing, and a method for producing the same.

A developing method using a dry toner whose main components are a colorant and a resin is as follows: 1) The dry toner is mixed with a carrier whose particle size is larger than that of the toner, and the toner is charged with a polarity opposite to that of the electrostatic latent image by frictional charging. A two-component developer for developing an electrostatic latent image by bringing a developer, which is a mixture of toner and carrier, into contact with the electrostatic latent image 11) Bringing a toner containing a magnetic substance into contact with or near the electrostatic latent image Develop - There are component developers.

Conventionally, in order to obtain these toners, thermoplastic resin was melted, coloring agents such as dyes and pigments, and if necessary magnetic materials, tribostatic charge control agents, anti-offset agents, lubricants, etc. were added and thoroughly mixed. After that, it was cooled and solidified, pulverized, and then classified to obtain the required particle size.

However, the methods described above have various drawbacks.

Firstly, many processes require equipment such as polymerization equipment for resin production, loading for cross-circuiting, pulverizers, classifiers, etc., and the number of steps is large and energy consumption is large, which results in high costs. This is the cause of the increase. The second reason is that it is difficult to obtain a uniform mixture in the mixing process, and the conditions for uniform dispersion are particularly delicate. Thirdly, in the grinding process, it is not possible to obtain only the appropriate fine powder particle size range to obtain clear, fog-free images; fine powder and coarse powder are by-products that must be classified and removed. There are disadvantages that lead to increased costs, such as complicated processes such as failure to obtain a desired particle size range, and poor yield for obtaining a desired particle size range. Fourth, the resulting powder has an amorphous shape due to the pulverization, resulting in poor fluidity of the fine powder and image fogging caused by the fine powder generated by both pulverization due to stirring during frictional charging. It will be done.

In contrast, Special Publication No. 36-10231, Special Publication No. 10231, Special Publication No. 47-
Publications such as Japanese Patent Publication No. 518305 and Japanese Patent Publication No. 51-14895 describe methods for producing toner by suspension polymerization. This suspension polymerization method does not require pulverization and the manufacturing process is simplified, and can be said to have improved the above-mentioned drawbacks. However, there is an opening angle associated with suspension polymerization.

In other words, dry toner uses thermoplastic resin as its living body, but it is mixed with materials to impart and improve the functions of 6 Yuzu, such as coloring agents such as dyes and additives, and charging agents to improve triboelectric charging properties. Examples include a control agent, a magnetic material that provides adhesion to the dust image roller, an anti-offset agent that prevents toner from adhering to the fixing roller, and a toner fluidity improver. There is no particular problem if these materials dissolve uniformly in the polymerizable monomer and do not inhibit the polymerization reaction, but many of the substances added are insoluble or sparingly soluble in the polymerizable monomer and are Due to their lack of affinity for monomers, it is difficult to make these materials exist uniformly in polymer particles. If the added material has a poor affinity for the polymerizable monomer, it may migrate to the aqueous phase during polymerization and may not exist in the polymerized toner particles.

Since the added materials are non-uniformly present in the toner, the toner cannot fully perform its functions, such as not being sufficiently charged.

In particular, cardan black, which is used as a colorant or a charge control agent, is lipophilic but has a primary particle size of 10 m11.
Primary aggregates that are as fine as ~30 mμ and slippery during manufacturing,
Furthermore, secondary aggregates with advanced agglomeration are formed, and it is difficult to disperse them in the polymerizable monomer simply by dispersion means such as a ball mill, and toner particles containing poorly dispersed carmen black The blackness of the toner is low 5- Not only is it not possible to obtain a dark black image, but it also increases the variation in the electrical resistance and frictional charge amount of the toner particles, making it impossible to obtain excellent image quality. JP-A-56-116044, JP-A-56-12355
Publications such as No. 3 and JP-A-57-37354 describe methods for improving the dispersion of carmen in toners produced by suspension polymerization. However, both of these methods increase the number of manufacturing steps, and increasing the number of manufacturing steps reduces the advantages of suspension polymerization. However, there is a problem in that the dependence of electrical properties such as triboelectrification on hybridization increases.

Therefore, it is desirable to disperse carmen black into the polymerizable monomer simultaneously with other additives in one step. Furthermore, the Kazen Black dispersant used for this purpose must not be one that adversely affects the electrical resistance, triboelectric charging characteristics, and thermal characteristics of the toner, and reduces the moisture resistance, durability, storage stability, etc. of the toner. 6- No.

The first object of the present invention is to provide a toner with sufficient carbon black dispersion and excellent image quality, and the second object is to produce a toner that improves the drawbacks of the suspension polymerization method. The purpose is to provide a method.

In order to achieve the above goal, the inventors of the present invention have conducted extensive research and found that carbon black is dispersed in a polymerizable monomer containing an organic titanate compound, or carbon black is surface-treated with an organic titanate compound. The inventors have discovered that the dispersion state of carbon black is significantly improved when black is dispersed in a polymerizable monomer, leading to the present invention.

The organic titanate compound used in the present invention is (wherein R
1 represents a C1-C8 straight-chain or branched alkyl group, and R2 represents a C1-C3° straight-chain or branched alkyl group. ) is expressed by the general formula.

A toner containing this organic titanate compound and a method for producing the same will be described in detail.

Surface treatment of cardin black with an organic titanate compound is carried out by immersing carbon black in a solution in which the organic titanate compound is dissolved to form a slurry, and then removing the solution by rinsing or drying under reduced pressure. After removing the bath agent, it is preferable to further heat the treatment. Such a treatment method is particularly preferred when other additives are reactive with the organic titanate compound. Next, the surface-treated carbon black and additives such as a polymerization initiator are dispersed in a polymerizable monomer to prepare an oil phase liquid.

In addition, when polymers, oligomers, etc. are added together with carbon black to the polymerizable monomer, carbon black and organic titanate compounds are added to the molten polymer or oligomer and dispersed in a kneader, etc., and then added to the polymerizable monomer. It may also be added to the oil phase to crack the oil phase liquid.

Next, the dispersion of the oil phase is added to the aqueous phase in which inorganic powder, a dispersion stabilizer such as a water-soluble polymer, and a monomer inhibitor, etc. in the aqueous phase are uniformly dissolved or dispersed. It is dispersed into oil droplets of 5 to 30 μm using a dispersing means such as the above. The weight ratio of the oil phase to the aqueous phase is in the range of 1:2 to 1:10, and is set in such a range that coalescence of particles does not occur during polymerization.

The dispersion liquid in which the oil phase is uniformly dispersed in the aqueous phase is transferred to a paraple flask equipped with a stirrer, a condenser, a thermometer, and a nitrogen inlet tube, and the temperature at which the polymerization initiator decomposes (50 to 90°C) is transferred.
) to carry out polymerization under a nitrogen stream.

If inorganic powder is attached to the surface of the toner, remove it by treating it with dilute acid, and after washing with water, remove the water by spray drying, vacuum drying, etc., and remove the water phase. Manufactured.

Specific examples of polymerizable monomers and various additives that can be used in the present invention are as follows.

Monopolymerizable monomer: includes all polymerizable monomers, but especially styrene, methyl methacrylate, methyl acrylate, vinyl chloride, ethylene, vinyl methyl ether, vinyl methyl ketone, N-vinyl Vinyl compounds such as carbazole are preferred. Further, divinyl compounds such as divinylbenzene, ethylene glycol diacrylate, and trimethylolpropane triacrylate can also be used in an amount of 0.005% to 20% by weight based on the vinyl compound.

Polymerization initiator: 2 g Azo compounds such as 2'-azobisisobutyronitrile and 2,2'-azobis-2,4-dimethylvaleronitrile, peroxides such as benzoyl peroxide and lauroyl oxide used.

Furthermore, a chain transfer agent such as dodecyl mercaptan can be used to suppress the molecular weight of the polymer within a required range.

Pigments such as dicasene black, cyanine, and quicnathrin, and dyes such as aniline black and nigrosine are used as colorants. These dyes can be used as charge control agents if they have excellent tribostatic properties.

Magnetic material A ferromagnetic material with fine particles of 1 μm or less, such as iron dioxide, ferrite, and iron, is used, and especially when it is black, it can be used without adding a coloring material.

Polymer, oligomer, prepolymer: polyethylene,
Polypropylene, ethylene acetate vinylimer, chlorinated polyethylene wax, polyamide, polyester, polyurethane, polyvinyl butyral, butadiene rubber, phenolic resin, epoxy resin, rosin modified resin, silicone oil, silicone wax to prevent offset, improve fluidity, and improve fixing properties. It can be used for purposes such as improvement and improving fluidity.

In addition, in order to uniformly disperse the oil phase consisting of polymerizable monomers and additives in the aqueous phase, poorly water-soluble fine powders such as silica, alumina, talc, and calcium carbonate, or polyvinyl alcohol, hydroxycellulose, gelatin, etc. Water-soluble polymers can be used alone or in combination. Furthermore, a surfactant such as sodium dodecylbenzenesulfonate may be used together with an inorganic fine powder or a water-soluble polymer. Furthermore, adding a one-coupling inhibitor such as ferric chloride, ammonium thiocyanate, or hydrogen peroxide to the aqueous phase is effective in preventing the generation of ultrafine particles due to emulsion polymerization.

Next, examples of the present invention will be shown.

Example 1 Isozorobyldecylbenzenesulfonyl titanate 0
．． 5 parts were dissolved in 50 parts of toluene, and carbon black 5II was immersed in this. Thereafter, the solvent was evaporated while stirring on a 60°C water bath. Thereafter, it was heat-treated at 120° C. for 2 hours to obtain surface-modified carbon black powder. On the other hand, 0.4 g of low molecular weight polypropylene 4.9 negatively charged dye and the above surface-modified carbon black 2I were added to styrene 409 and dispersed in a Zeel mill for 9 hours. Add 2,2
'-azobis(2,4-dimethyl)valeronitrile 0.
After dissolving 42 parts of polyvinyl alcohol (polymerization degree 5
The mixture was added to a 160.9 inch water bath solution with a saponification degree of 88 degrees) and stirred for 1 minute using a homomixer (3000 rpm). Carbon black is uniformly dispersed in the oil droplets after stirring.
It was completely black in color. This suspension was reacted in a seven-paraple flask at 60° C. for 6 hours under a nitrogen stream to obtain a suspension of polymer particles. This was centrifuged, washed with water repeatedly, and then dry-recorded under reduced pressure to obtain spherical black toner powder. This toner showed a charge amount of -12.8 μc/l when measured with a blow-off device. Mixed with carrier iron powder, Ricobi-F
When developed with T6200, a clear black image was obtained.

Comparative Example Polymerization was carried out under exactly the same conditions as in Example 1, except that 2.0 g of Cargin black without surface treatment was used.

The polymerizable mixture taken out from the mill mill showed agglomeration of carbon black, and the dispersion state was poor. The produced polymer was spherical particles with a size of 10 to 20μ, but carbon black was unevenly distributed in the particles, and there were quite a lot of transparent parts and transparent particles. It was more of a gray color. In addition, there is carbon black that is not incorporated into the particles and sticks to the particle surface,
It was confirmed that it existed alone. Also, the amount of charge is -2
, 8 μc/77. The reason for such a low charge amount is considered to be poor dispersion of carbon black.

Example 2 To 40 parts of styrene were added 2 parts of cardan black, 0.6 parts of isozolobyloctylbenzenesulfonyl titanate, 4 parts of low molecular weight polypropylene, and 0.8 parts of a positively charged dye, and the mixture was dispersed in a Zeel mill for 9 hours. This dispersion was suspended in a polyvinyl alcohol aqueous solution in the same manner as in Example 1. The suspended oil droplets were completely black and the carbon black was well dispersed. A polymerization initiator was added to this suspension in the same manner as in Example 1, and polymerization was carried out to obtain black spherical particles of 10 to 15 μm. When measuring the band VT scene with a pull-off device, it is 26
．． 8μc/I, and its electrical resistance value is 9.3X10ΩcR (I
KHz), which was a value that could be used as a toner. Further, even after mixing and stirring with the iron powder carrier in a pot mill, the toner remained spherical and was not crushed.

Example 3 Cardin Black 2I and 0.4 parts of isozolobuldecylbenzenesulfonyl titanate were added to 4 parts of molten low molecular weight polypropylene and dispersed using a roll mill. This was added to a mixed solution of 28 parts of styrene and 12 parts of n-butyl methacrylate, heated and then cooled to uniformly suspend Kazen black and polypropylene. 0.4 part of a negatively charged dye was added to this, and after dispersing for 4 hours in a sol mill, a polymerization initiator was added in the same manner as in Example 1, and the mixture was suspended in an aqueous phase. The suspended oil droplets were completely black and stable. This was polymerized in the same manner as in Example 1 to obtain spherical black particles of 10 to 15 microns. The charge amount of these particles was -11.7 μa/I, and the electrical resistance was 1.5×10 Ωα.

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Claims (1)

[Claims] 1. The following general formula (wherein R1 represents a C1 to C8 straight chain or branched alkyl group, and R1 represents a C1 to C6° straight chain or branched alkyl group). A toner for developing electrostatic images containing the organic titanate compound shown below. 2 After dispersing Kazen black in the polymerizable monomer,
In the method for producing a toner for developing electrostatic images by suspension polymerization, the following general formula (wherein R2 represents a C0 to C8 straight chain or branched alkyl group, R8 represents a straight chain of C,% C,. or a branched alkyl group.) A method for producing a toner for developing an electrostatic image, comprising dispersing cardin black in a polymerizable monomer in the presence of an organic titanate compound represented by the following.