JPS61255357A - Toner for developing electrostatic charge image and its production - Google Patents

Abstract

PURPOSE:To obtain a toner contg. a colorant with superior dispersibility, having an increased blackening degree and causing hardly fog during copying by dispersing carbon black in a monomer having a polymerizable unsatd. group in the presence of a specified alkylsalicylate compound. CONSTITUTION:This toner contains a polymer binder, carbon black and an alkylsalicylate compound represented by formula I. The amount of the compound added is <=10wt%, preferably 0.5-4wt% of the amount of a polymerizable monomer used. The compound and carbon black as a colorant are dispersed in the polymerizable monomer, and the monomer is polymerized in an oily phase by a suspension polymn. method to produce polymer particles.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] 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: I) The dry toner is mixed with a carrier having a particle size larger than 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 that develops the electrostatic latent image by bringing a developer, which is a mixture of toner and carrier, into contact with the electrostatic latent image.ii) A toner containing a magnetic substance is brought into contact with or in close proximity to the electrostatic latent image. There is a one-component developer used for development.

[Conventional technology and problems]

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. The method used was to cool and solidify the powder, pulverize it, and then classify it to obtain the desired particle size.

However, the methods described above have various drawbacks. Firstly, polymerization equipment for resin production, equipment for kneading,
Equipment associated with many processes, such as a crusher and a classifier, is required, and the number of processes and energy consumption is large, which causes high costs. The second reason is that it is difficult to obtain a uniform mixture in the kneading 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-produced and must be separated and removed). There are drawbacks that lead to increased costs, such as the complexity of the process and poor yield to obtain the desired particle size range.Fourth, the resulting powder has an irregular shape due to pulverization, and is not a fine powder. Capri of the image is caused by poor fluidity of the body and fine powder generated by re-grinding due to stirring during frictional charging.

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, simplifies the manufacturing process, and can be said to have improved the above-mentioned drawbacks. However, there are problems associated with suspension polymerization.

In other words, dry toner is mainly made of thermoplastic resin, but it is mixed with other materials to impart and improve various functions, such as coloring agents such as dyes and pigments, and charge control to improve triboelectric charging properties. toner, a magnetic material that provides adhesion to the developing roller, an anti-offset agent that prevents toner from adhering to the fixing roller, a toner fluidity improver, and the like.

If these materials dissolve uniformly in the polymerizable monomer and do not inhibit the polymerization reaction, there is no particular problem. It is difficult to make these materials exist in a uniform state in polymer particles because of their lack of affinity for polymeric monomers.

If the added material has a significantly 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, carbon black used as a colorant or charge control agent is lipophilic, but the particle size is 10 ta
In addition to being as fine as μ~30 r@μ, it forms primary aggregates that slip during production and secondary aggregates that are further agglomerated, and can be dispersed in polymerizable monomers simply by dispersion means such as a ball mill. Toner particles containing poorly dispersed carbon black not only reduce the blackness of the toner and make it impossible to obtain a black image, but also cause variations in the electrical resistance and triboelectric charge of the toner particles. It is not possible to increase the image quality and obtain excellent image quality.

SUMMARY OF THE INVENTION An object of the present invention is to provide a toner and a method for producing the toner that overcome the above-mentioned drawbacks. That is, the first object of the present invention is to provide a toner that has a sufficient carbon black dispersion state and provides excellent image quality.
The purpose of the present invention is to provide a method for producing toner that overcomes the drawbacks of suspension polymerization.

[Means for solving problems]

As a result of extensive research in order to achieve the above-mentioned goal, the present inventors discovered that a specific alkyl salicylate compound was present when dispersing carbon black in a monomer having a polymerizable unsaturated group. It has been discovered that the dispersibility of carbon black can be significantly improved by dispersing the carbon black, leading to the present invention.

That is, the present invention provides a binder polymer, a carbon blank, and the following general formula (1) (wherein R and R'' represent a straight chain or branched alkyl group having 6 to 100 carbon atoms, and R and R' are They may be the same or different (M is Ca, Mg, Ba.

Indicates alkaline earth metals such as Zn. ), and a monomer (hereinafter abbreviated as "polymerizable monomer") having a polymerizable unsaturated group; In a method for producing an electrostatic image developing toner by a suspension polymerization method after dispersing black, carbon black is added to a polymerizable monomer in the presence of an alkyl salicylate compound represented by the above general formula (1). The present invention relates to a method for producing a toner for developing an electrostatic image, which is characterized by dispersing and then polymerizing.

The alkyl salicylate compound represented by the general formula (I) used in the present invention is synthesized as follows. That is, for example, α having a double bond at the end and having 6 to 100 carbon atoms.
- First, an alkyl salicylic acid is synthesized by reaction of an olefin with salicylic acid. Next, the alkyl salicylic acid obtained in this way is treated with Ca, Mg, Ba, Zn.
to obtain the desired alkyl salicylate compound.

The amount of the alkyl salicylate compound represented by the general formula (1) used in the present invention is 10% by weight or less, preferably 0.5 to 4% by weight based on the polymerizable monomer.
Weight%.

In the present invention, the alkyl salicylate compound represented by the above general formula (I) and carbon black as a coloring agent are mixed and dispersed in a polymerizable monomer, this is used as an oil phase, and a suspended polymer is used. Polymer particles are produced by polymerization according to a legal method.

In the suspension polymerization method, a dispersion of the oil phase is added to an aqueous phase in which a suspension stabilizer such as a water-soluble polymer or a poorly water-soluble inorganic salt is uniformly dissolved or dispersed, and the dispersion is carried out using a homomixer, homogenizer, etc. Disperse into oil droplets of 5-30 μm depending on the method.

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. Transfer the dispersion liquid in which the oil phase is uniformly dispersed in the water phase to a separable flask equipped with a stirring device, condenser, thermometer, and nitrogen inlet tube, and raise the temperature to the temperature at which the polymerization initiator decomposes (50 to 90 °C). Then polymerization is carried out under a nitrogen atmosphere.

After the polymerization is completed, the aqueous phase is removed by filtration, and if inorganic powder is attached to the toner surface, it is removed by treatment with dilute acid, and after washing with water, water is removed by spray drying, vacuum drying, etc. until the toner is finished. Manufactured.

As the polymerizable monomer used in the present invention, all polymerizable monomers can be used, such as styrene, p
-Chlorstyrene, p-methylstyrene, vinyl acetate,
Vinyl propionate, vinyl benzoate, methyl acrylate, ethyl acrylate, n-butyl acrylate,
1so-butyl acrylate, dodecyl acrylate,
n-octyl acrylate, methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, 1s
o-Butyl methacrylate, diethylaminoethyl methacrylate, t-butylaminomethyl methacrylate, acrylonitrile, 2-vinylpyridine, 4-vinylpyridine and the like can be used alone or in combination.

Furthermore, in the present invention, by adding polyfunctional monomers such as divinylbenzene, ethylene glycol dimethacrylate, trimethylolpropane triacrylate, glycidyl methacrylate, and glycidyl acrylate to the above monomers as a crosslinking agent, a toner with even better durability can be obtained. Can be manufactured. The content of the polyfunctional monomer is 0.05 to 20% by weight (preferably 0.05 to 20% by weight, preferably 0
．． 5 to 5% by weight) is good.

As the polymerization initiator, commonly used oil-soluble peroxide-based or azo-based initiators can be used. For example, benzoyl peroxide, lauroyl peroxide, 2,2°-azobisisobutyronitrile, 2,2°-azobis-(2,4-
dimethylvaleronitrile), orthochlorobenzoyl peroxide, and orthomethoxybenzoyl peroxide.

These are 0.1 to 10% by weight based on the polymerizable monomer,
Preferably it is used in an amount of 0.5 to 5% by weight.

Suspension stabilizers used in the present invention include water-soluble polymers such as gelatin, starch, hydroxyethyl cellulose, carboxymethyl cellulose, polyvinylpyrrolidone, polyvinyl alkyl ether, and polyvinyl alcohol;
Examples include poorly water-soluble inorganic salts such as barium sulfate, calcium sulfate, barium carbonate, calcium carbonate, magnesium carbonate, and calcium phosphate, and these are used in an amount of 0.1 to 5% by weight, preferably 0.5 to 2% by weight of water. .

Further, the toner of the present invention may contain a low molecular weight olefin polymer known as a so-called mold release agent for the purpose of preventing offset, improving fluidity, improving fixing properties, etc.

It is preferable that this low molecular weight olefin polymer be present during monomer polymerization together with the colorant used in the present invention.

Examples of the low molecular weight olefin polymer used in the toner of the present invention include polyethylene, polypropylene, ethylene acetate picopolymer, chlorinated polyethylene wax, polyamide, polyester, polyurethane, polyvinyl butyral, butadiene rubber, phenolic resin, epoxy resin, and rosin. Examples include modified resins, silicone oils, and silicone waxes.

The amount of the low molecular weight olefin polymer used is 1 to 20 parts by weight, preferably 3 parts by weight, per 100 parts by weight of the resin component of the toner.
The amount is 15 parts by weight or less, and if it is less than 1 part by weight, it may not have a sufficient offset prevention effect, and if it is more than 20 parts by weight, gelation may occur during polymerization, which is not preferable.

To form an image using the toner of the present invention, for example, by electrophotography, a selenium photoreceptor or an inorganic photoconductive material such as zinc oxide, cadmium sulfide, cadmium selenide, cadmium selenide sulfide, lead oxide, mercury sulfide, etc. A photoreceptor in which a photosensitive layer containing a material dispersed in a binder resin is provided on a conductive support, or an organic photoconductive material such as anthracene or polyvinylcarbazole is contained in a binder resin as necessary. A photoreceptor is used in which a photosensitive layer is provided on a conductive support. The surface of the photosensitive layer of such a photoreceptor is entirely charged by corona discharge using, for example, a corotron or scorotron charger, and then imagewise exposed to light or the like to form an electrostatic charge image. Next, this electrostatic charge image is developed, for example, by a cascade method or a magnetic brush method, with a developer consisting of a mixture of the toner of the present invention and a glass beads or iron powder carrier to form a toner image. This toner image is transferred onto the transfer paper by being pressed against the transfer paper under, for example, corona discharge. The toner image transferred onto the transfer paper is heat-fixed by a hot roll fixing device coated with a fluorine-based resin or silicone rubber having mold-releasing properties.

〔Effect of the invention〕

As explained above in detail, the toner for developing electrostatic images of the present invention is produced by mixing and dispersing a specific dispersion stabilizer together with a colorant in a monomer, and then suspension polymerizing the mixture to form granulated polymer particles. As a result, we were able to obtain a toner with even better colorant dispersibility than toner produced using conventional manufacturing methods, which not only improved the degree of toner blackening and generation of capri during copying, but also improved development efficiency. It was also possible to provide a toner that was further improved in terms of properties, transferability, fixing properties, and storage stability, as well as a method for producing the same.

〔Example〕

Examples of the present invention are shown below, but the present invention is not limited thereto.

"Parts" in the examples are "parts by weight."

Example-1 85 parts of styrene, 15 parts of n-butyl acrylate, 6 parts of carbon black (manufactured by Mitsubishi Kasei ■, #44), 2 parts of calcium lauryl salicylate salt, low molecular weight polyethylene (special product of Mikata Petrochemical Industries, Mikata High Wax 210P)
The two parts of the mixture were dispersed in a ball mill for 10 hours. After dissolving 1 part of 2.2'-azobisisobutyronitrile in this dispersion, 250 g
The mixture was stirred for 3 minutes at 6000 rpm using a TK homo mixer (manufactured by Tokushu Kika Kogyo ■). When the oil droplets after stirring were observed under an optical microscope, the dispersibility of carbon black in the oil droplets was extremely good. This suspension was subjected to a polymerization reaction in a separable flask at 75° C. for 8 hours under a nitrogen atmosphere at a stirring speed of 100 rpm+ using an ordinary stirrer. After the polymerization was completed, centrifugation and water washing were repeated, followed by drying under reduced pressure to obtain a spherical toner with an average particle size of 11 μm.

Carrier iron powder (D, M) to 5 parts of Kono toner.

95 parts of CB-100 (manufactured by Sceart) were mixed to prepare a developer. When this developer was used to create an image using Ricoh FT4060, a clear black image without fogging was obtained.

Comparative Example-1 Polymerization was carried out under exactly the same conditions as in Example-1 except that calcium lauryl salicylate was not added.

In the polymerizable mixture taken out from the ball mill, agglomeration of carbon black was observed, and the dispersion state was poor. The produced polymer was spherical particles of 10 to 20μ, but the carbon black was unevenly distributed in the particles, and there were quite a lot of transparent parts and transparent particles, and the obtained powder was not black. Rather, it looked gray. It was also confirmed that carbon black that was not incorporated into the particles was found to be stuck to the particle surface or existing alone. When an image was produced using this toner in the same manner as in Example 1, the image density was insufficient and fogging also occurred.

Example 2 A toner was produced in the same manner as in Example 1 except that calcium stearylsalicylate was used instead of calcium laurylsalicylate. When an image was produced using this toner in the same manner as in Example 1, a clear image with sufficient image density and no fogging was obtained.

Example-3 80 parts of styrene, 10 parts of n-butyl methacrylate, 2
- 10 parts of ethylhexyl acrylate, 5 parts of carbon black (manufactured by Mitsubishi Kasei ■, #30), 1 part of octylsalicylic acid calcium salt, 1.5 parts of low molecular weight polyethylene (manufactured by Mikata Petrochemical Industries ■, Mikata Hiwafukus 4052B) The mixture was dispersed in a ball mill for 10 hours. After dissolving 2 parts of 2,2'-azobis=(2,4-dimethylvaleronitrile) in this dispersion, 1.5 parts of polyvinyl alcohol (Gosenol GM-14, manufactured by Nippon Gosei Kagaku Kogyo ■)
% aqueous solution and stirred for 3 minutes at 7000 rpm using a TK homomixer (manufactured by Tokushu Kika Kogyo ■).

Thereafter, a spherical toner with an average particle size of 10 μm was produced in the same manner as in Example-1, and an image was produced in the same manner as in Example-1. No clear images were obtained.

Example-4 Example-3 except that an alkyl salicylic acid magnesium salt in which the average number of carbon atoms in the alkyl group is 50 is used instead of the octylsalicylic acid calcium salt in Example-3.
A toner was produced in the same manner as in Example 3. When an image was produced using this toner in the same manner as in Example 1, a clear image with sufficient image density and no fogging was obtained.

Claims (1)

[Claims] 1 Binder polymer, carbon black, and the following general formula (I) ▲ Numerical formulas, chemical formulas, tables, etc. are included ▼ (I) (In the formula, R and R' are straight carbon atoms with 6 to 100 carbon atoms. (representing a chain or branched alkyl group, R and R' may be the same or different, and M represents an alkaline earth metal). Toner for developing electrostatic images. 2. In a method for producing an electrostatic image developing toner by a suspension polymerization method after dispersing carbon black in a monomer having a polymerizable unsaturated group, the following general formula (I) ▲ mathematical formula, chemical formula, table etc.▼(I) (In the formula, R and R' represent a straight chain or branched alkyl group having 6 to 100 carbon atoms, R and R' may be the same or different, and M is Electrostatic image development characterized by dispersing carbon black in a monomer having a polymerizable unsaturated group in the presence of an alkyl salicylate compound represented by alkaline earth metal (alkaline earth metal), and then polymerizing it. method for producing toner for use in