KR0131566B1 - Method for producing electrophotographic toners - Google Patents

Abstract

The present invention is an electrophotographic one-component system comprising a 25-75 wt% melt-mixing of a magnetic substance obtained by treating a coupling agent at a line speed of 25 m / sec or more with a vinyl binder resin having an acid value of 15 KOH mg / g or more based on toner particles. A method for producing toner. The toner according to the present invention is excellent in dispersibility and has a uniform charging characteristic, resulting in a stable image.

Description

Manufacturing method of one-component toner for electrophotographic

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a method for manufacturing a toner used in an electrophotographic process such as an electronic copying machine and a laser beam printer, and more particularly, to the production of an electrophotographic one-component toner which exhibits a stable image with excellent dispersibility and uniform charging characteristics. It is about a method.

In general, an electrophotographic process used in an electron copying machine, a laser beam printer, and the like will be described in which electric potential is caused by a corona discharge or the like on a photoconductor using a photoconductor. An original image is formed on the photosensitive member thus charged through an optical lens, or an image is formed by an optical signal by a laser beam, and the potential of the photosensitive member surface is lowered according to the amount of light irradiated to form an electrostatic latent image. Then, the electrostatic latent image is visualized by bringing the toner charged in various forms into contact with or in proximity to the latent electrostatic image. The visualized toner image thus obtained is transferred to paper by electrostatic force, and subjected to heat, pressure or light. Is applied to fix the transferred toner image.

The toner used in such an electrophotographic method is largely made by a mechanical grinding method, a polymerization method, etc. However, in comparison with the problems such as economic efficiency and productivity, the mechanical grinding method which is comparatively superior to the present technology is commercially available. Widely used.

Looking at the manufacturing method of the toner by the mechanical grinding method is as follows. Won first. After weighing the sub-materials at a fixed mixing ratio, premix them with a mixer to mix the raw materials evenly. Thereafter, the preliminarily kneaded raw materials are melt mixed using a kneader, a roll mill, or a Banbury mixer to obtain a molten mixture in which the raw materials are evenly dispersed and mixed. After cooling the molten mixture thus obtained, coarsely pulverized to a size of 1 to 3 mm, and finely pulverized by using a jet mill or the like, and a toner having a desired particle size distribution is obtained through a classification process. If the toner is used as it is, it is difficult to be used because it is inferior in operability. Therefore, when the toner for use is separately mixed to increase the fluidity of the toner, it can be used as an electrophotographic toner.

The toner thus prepared can be broadly classified into one used in the two-component developing method and one used in the one-component developing method. The two-component system has a problem in that the developing device is enlarged in order to maintain the density of the toner in the developer because the developer deteriorates or the consumption of the toner increases due to the adhesion of the toner particles to the carrier surface. However, since the one-component developing method does not have the above problems, the apparatus can be miniaturized, and thus, the developing method has become mainstream. Various proposals have been made for the one-component developing toner. Conventional one-component developing toners tend to be difficult to obtain excellent images due to uneven dispersion of raw materials. In particular, since the one-component developing toner contains a magnetic material, dispersion with the binder resin is very important.

In the case of using the vinyl resin as the binder resin in the one-component toner, if the magnetic component is poorly dispersed in the binder resin, the dispersion state of the magnetic material for each of the toner particles becomes uneven, and the magnetic force between the toner particles is severely generated. . As a result, when the low-power toner adheres to the background portion of the image, contamination occurs. Further, in the pulverizing step, the toner is pulverized in the aggregate portion of the magnetic powder, and as a result, the magnetic powder tends to be liberated, and when developed, there is a problem that the photoconductor is moved to the surface of the photoconductor, resulting in contamination of the photoconductor. In the one-component toner, it is very important to uniformly disperse the magnetic material in the binder resin, and those with improved dispersibility are demanded.

In Japanese Patent Laid-Open Nos. 90-3078 and 92-314057, a one-component toner using a magnetic material that has only been treated with a coupling agent was prepared. However, when the acid value of the binder resin used is less than a certain value, the magnetic material and the binder resin are used. The improvement of liver dispersal could not be expected. In addition, when the coupling treatment is performed on the magnetic material, the coupling agent is unevenly coated on the surface of the magnetic material when the mixer is less than a constant linear velocity, and thus dispersibility cannot be improved.

The present inventors have diligently studied to solve the above problems, and as a result, in the vinyl-based resin used as a binder, the inventors select a resin having a fixed acid value or more, and treat the coupling agent by a special method to increase the dispersion and bonding strength with the magnetic body. The use of one resulted in the improvement of the dispersibility of the magnetic material and the fixability of the toner, thus completing the present invention.

SUMMARY OF THE INVENTION An object of the present invention is a one-component toner for electrophotographic which has good fixability, is excellent in powder separation of a magnetic substance in resin, has uniform charging characteristics, and solves the problem caused by poor dispersion of the magnetic substance to obtain an excellent image. To provide.

In other words, the present invention is characterized in that the mixture of 25 to 75% by weight of the magnetic material obtained by treating the coupling agent to the linear velocity of 25m / sec or more to the vinyl binder resin having an acid value of 15KOH mg / g or more to the toner particles A method of manufacturing a one-component toner.

Hereinafter, the manufacturing method of the present invention will be described in detail.

The vinyl binder resin used in the one-component toner of the present invention needs to have an acid value of 15 KOH mg / g or more. In the present invention, the dispersibility of the magnetic material is determined by the dielectric dissipation factor (tan δ) of the toner particles. If this value is small, the dispersibility of the magnetic body is good. In the case of the vinyl binder resin, when the acid value is 15 KOH mg / g or more, the tan δ value is 1 × 10 ⁻² or less. As a result, the dispersibility of the magnetic component is very good. It becomes higher and improves settling. It is thought that this is because acid value contributes to the interaction with cellulose which is a main component in paper. If the acid value is less than 15KOH mg / g is difficult to expect the above action.

In the present invention, the vinyl binder resin may be a copolymer of a vinyl monomer and a copolymerizable monomer capable of imparting a desired acid value. Vinyl monomers include styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, p-methoxystyrene, p-phenylstyrene, p-chlorostyrene, 3,4-dichlorostyrene, p-ethylstyrene, 2 Styrene derivatives such as, 4-dimethylstyrene, pn-butylstyrene, p-tert-butylstyrene, pn-hexylstyrene, pn-octylstyrene pn-nonylstyrene, pn-decylstyrene and pn-dodecylstyrene; Ethylenically unsaturated monoolefins such as ethylene, propylene, butylene and isobutylene; Vinyl halides such as vinyl chloride, vinylidene chloride, vinyl bromide and vinyl fluoride; Vinyl esters such as vinyl acetate, vinyl propionate and vinyl benzoate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, n-octyl methacrylate, methacrylate Methacrylic acid esters such as acid dodecyl, 2-ethylhexyl methacrylate, stearyl methacrylate, fail methacrylate, dimethylaminoethyl methacrylate and ethylaminoethyl methacrylate; Acrylic esters such as methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, propyl acrylate, n-octyl acrylate, dodecyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, 2-chloroethyl acrylate and phenyl acrylate; Vinyl ethers such as vinyl methyl ether, vinyl ethyl ether and vinyl isobutyl ether; Vinyl ketones such as vinyl methyl ketone, vinyl hexyl ketone and methyl isopropylphenyl ketone; vinyl ketones such as n-vinylpyrrole, n-vinylcarbazole, n-vinylindole and n-vinylpyrroladon; and acrylic acid derivatives such as n-vinyl compound, vinylnaphthalene, acrylonitrile, methacrylonitrile and acrylamide, or methacrylic acid derivatives.

In addition, the copolymerizable monomer which gives a desired acid value is ethylenic unsaturated carboxylic acid or anhydride, specifically acrylic acid, methacrylic acid, crotonic acid, fumaric acid, maleic acid, maleic anhydride, itaconic acid, itaconic anhydride, tetrahydro Copolymers such as phthalic anhydride.

Preferred vinyl binder resins in the present invention include styrene maleic anhydride copolymer, styrene acrylate acrylic acid copolymer, styrene acrylate butyl methacrylic acid copolymer, styrene methacrylate methyl methacrylic acid copolymer, and styrene 2-ethylhexyl acrylate. Methacrylic acid copolymer, 2-ethylhexyl methacrylate copolymer, styrene butyl butyl maleic anhydride copolymer, styrene methyl acrylate maleic acid copolymer, styrene vinyl methyl ether acrylic acid copolymer, styrene butadiene acrylic acid copolymer etc. are mentioned. can do.

The magnetic material used in the present invention is a special method of treating the coupling agent, and the magnetic fine particles used in the one-component toner include iron, cobalt, nickel and other metals and alloys thereof, Fe ₃ O ₄ , γ-Fe ₂ O ₃ , Metal oxides, such as cobalt addition iron oxide, Mn * Zn ferrite, Ni * Zn ferrite, magnetite, hematite, etc. are used. The particle diameter of these magnetic bodies is preferably in the range of 0.1 to 1 mu m, and more preferably in the range of 0.2 to 0.5 mu m.

In the present invention, as described above, a fling agent obtained by treating a coupling agent with such a low substance is used, and preferred coupling agents include a silane coupling agent and a titanate coupling agent. In general, when hydrophilic magnetic surface is treated with a coupling agent, it is hydrophobized to increase the dispersibility of magnetic fine particles in the resin, and the binding force between organic binder resin and inorganic magnetic siding is also increased. It can be evenly distributed. Coupling agents which can be used in this way are isobutyltrimethoxysilane, mercaptopropyltrimethoxysilane, aminopropyltriethoxysilane, 3-methacryloxypropyltrimethoxysilane, n- (2- Aminoethyl) -3-aminopropanetrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, n-octyltriethoxysilane, 3-chloropropyltriethoxysilane, n- (2- (vinylbenzylamino ) -3-aminopropyltrimethoxysilane, vinyltriacetoxysilane, etc., and titanate-based coupling agents include isopropyltriisostearoyl titanate, isopropyl-tridecylbenzenesulfontitanate, isopropyl- Tris (dioctylpyrophosphate) -titanate, tetraisopropyl-bis (dioctylphosphate) -titanate, tetraoctylbis (ditridecylphosphate) titanate, tetra (2,2-diaryloxy-methyl- 1-butyl) bis (ditride) ) Phosphate, bis (dioctylpyrophosphate) oxy-acetate titanate, bis (dioctylpyrophosphate) ethylene titanate, isopropyl tri-octanyl titanate, isopropyldimethacryl-isostearol-tita Nitrate, isopropyl-isostearol-diacrylitanate, isopropyl-tri (dioctylphosphate) titanate, isopropyl-tricumylphenyl titanate, isopropyl tri (n-aminoethyl, aminoethyl) titanate , Dicumylphenyloxyacetate titanate, diisostearoylethylene titanate, and the like.

The throughput of the coupling agent described above in the present invention is preferably used in the range of 0.1 to 4 parts by weight, more preferably 0.5 to 1.0 part by weight based on the magnetic material.

There are various methods for treating the coupling agent to the magnetic material. In the present invention, it is preferable to perform the coupling agent in a Henschel type mixer, and in particular, the linear velocity is preferably treated at 25 m / sec or more. If the linear velocity is less than 25 m / sec, it is not evenly coated on the magnetic material, which does not contribute sufficiently to the dispersibility. The one-component toner of the present invention is produced by melt-mixing the above-described vinyl binder resin with a magnetic material that has been treated with a coupling agent in advance, followed by pulverizing and classifying.

The mixing ratio of the magnetic body is preferably 25 to 75% by weight, more particularly 35 to 55% by weight based on the toner particles. When the mixing ratio of the magnetic material is 25% by weight or less, the resolution, fine line reproducibility and gradation deteriorate, and when it is 75% by weight or more, the transfer efficiency is lowered under high temperature and high humidity environment. The average particle diameter of the toner particles is preferably in the range of 5 to 15 mu m.

The one-component toner according to the present invention may be used in combination with other components, if necessary. For example, various substances may be added according to the purpose of the charge control agent, the electric resistance agent, the colorant, and the like. For example, carbon black etc. can be added with azine salts, such as a metal salicylate complex with a fluorine-type surfactant salicylate chromium complex, and a quaternary ammonium salt nigrosine dye. Even if a release agent is added to improve offset resistance, paraffin waxes such as low molecular weight polypropylene, microcrystalline waxes, and the like are used as the release agent.

In addition, inorganic fine powders such as silaca, organic fine powders such as fatty acids or derivatives thereof, and metal salts, fine fluorine resin powders and the like can be added for the purpose of improving durability and fluidity and cleaning properties of the toner.

In the one-component toner of the present invention formed as described above, the magnetic body is dispersed in the binder resin in an excellent dispersion state so that the magnetic particles do not fall on the surface of the toner. Therefore, the one-component toner of the present invention does not have a difference in magnetic content between the toner particles, so that toner particles having a small magnetic content do not selectively adhere to the background portion. In addition, since the magnetic substance does not fall from the toner particles, it does not adhere to the surface of the photoconductor and cause contamination or damage.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the technical scope of the present invention is not limited to these Examples.

The vinyl binder resin used in the experiment is shown in Table 1 below.

The low phase body which processed the coupling agent used for the experiment is as follows.

(Magnetic material A)

After mixing 1 part by weight of 3-methacryloxypropyl trimethoxy silane with 9 parts by weight of methanol, 90 parts by weight of a magnetic substance (trade name: KBC100, manufactured by Kanto Denka Co., Ltd.) and a Henschel mixer were used in an oven at 50 ° C. at a linear speed of 25 m / sec. Magnetic body treated with coupling agent obtained after 48 hours.

(Magnetic material B)

It is the same as magnetic substance A except that 0.1 parts by weight of 3-methacryloxypropyl trimethoxy silane is used.

(Magnetic material C)

It is the same as magnetic substance A except that 4.0 parts by weight of 3-methacryloxypropyl trimethoxy silane is used.

(Magnetic material D)

It is the same as magnetic substance A except that 5.0 parts by weight of 3-methacryloxypropyl trimethoxy silane is used.

(Magnetic material E)

It is the same as magnetic material A except that the magnetic speed is obtained after stirring for 15 minutes at 10m / sec when using Henschel mixer.

(Magnetic material F)

It is the same as magnetic material A except that the magnetic speed is obtained after stirring for 15 minutes at 30m / sec when using Henschel mixer.

Example 1

100 parts by weight of the resin B, 100 parts by weight of the magnetic body A, and 3 parts by weight of a charge control agent (trade name: Bontron P-51, manufactured by Orient, Japan).

The three mixtures were melt mixed, pulverized and classified to obtain a one-component toter. This toner is shown in Table 2 comparing the dispersibility by transmission electrophotographic (TEM) and dielectric peak (tan δ) value.

Example 2

It is the same as Example 1 except having replaced resin B with resin C.

Example 3

Except having replaced the magnetic substance A with the magnetic substance B, it is the same as Example 1.

Example 4

Except having replaced the magnetic substance A with the magnetic substance C, it is the same as Example 1.

Example 5

It is the same as Example 1 except having replaced magnetic substance A with magnetic substance F. FIG.

Comparative Example 1

In Example 1, it is the same as Example 1 except having replaced resin B with resin A.

Comparative Example 2

In Example 5, it is the same as Example 5 except having replaced resin B with resin A.

Comparative Example 3

Except for replacing the magnetic substance A with the magnetic substance D in Example 1, it is the same as in Example 1.

[Comparative Example 4]

Except for replacing the magnetic substance A with the magnetic substance E in Example 1, it is the same as in Example 1.

[Comparative Example 5]

In Example 1, magnetic substance A was replaced with the magnetic substance which was not processed by the coupling agent, and is the same as Example 1.

In the molecular weight measurement used in the present invention, the THF soluble content of the polymer was measured by gel permeation chromatography (GPC), and then a calibration curve of standard polystyrene was used. Genetic tangency was measured using a test fitment 16451B on the LCR test meta (HP 4275A) of Hewlett-Peckert, USA. The surface contamination evaluation was judged to be observed while printing 500 sheets in an experimental chart using a laser method printer using an organic photoconductor (GLP-1150, manufactured by Venus), and photocontamination contamination was also visually determined. These results are also shown in Table 2.

O in ground pollution means no ground pollution, △ means negligible but slight, and X means severe ground contamination. Visually, the state of the photoconductor with no deposit on the surface of the photoconductor was marked with O, and the state with the deposit was indicated with X.

Fixability is between the printed black portion and the white paper with an eraser 20 times with a constant force to observe the toner drop out of the dark black portion and contamination on the white paper portion, and O (no at all) is dropped. ) And X (there were many droppings and contaminations).

Fixability evaluation results are also shown in Table 2.

It can be seen from Table 2 that even when a resin having an acid value of 15 KOH mg / g or more was used, the dispersibility was excellent, there was no ground pollution, photosensitivity and excellent fixability. When the coupling agent is treated with a magnetic material, when the magnetic material treated at a linear velocity of 20 m / sec or less is used, the dispersibility is not significantly improved even when a resin having an acid value of 15 KOH mg / g or more is used.

When the throughput of the coupling agent in the magnetic body was outside the range of 0.1 to 4.0 parts by weight, improvement in dispersibility could not be expected. The one-component toner of the present invention uses the above-mentioned raw materials to keep the magnetic body in a very good dispersion state in the binder resin. Therefore, when the toner of the present invention was used, the problem of surface contamination caused by deviation of magnetic force between toner particles was improved, and the problem of photoreceptor contamination caused by the freezing of agglomerated parts of the magnetic material occurred in the crushing process did not occur, and it was compatible with paper. It also showed good fixability due to good properties.

Therefore, it can be seen that the manufacturing method of the electrophotographic toner according to the present invention is a very useful invention in the art.

Claims (7)

Preparation of an electrophotographic one-component toner, characterized in that 25 to 75 Joule% melt mixing is performed on a toner particle with a magnetic substance obtained by treating the vinyl binder resin having an acid value of 15 KOH mg / g or more with a coupling agent at a linear speed of 25 m / sec or more. Way. The vinyl binder resin according to claim 1, wherein the vinyl binder resin is a styrene maleic anhydride copolymer, a styrene methyl acrylate acrylic acid copolymer, a styrene butyl methacrylate copolymer, a styrene methacrylate butyl methacrylic acid copolymer, or a styrene 2-ethylhexyl acrylate. Methacrylic acid copolymer, styrene 2-ethylhexyl-methacrylic acid copolymer, butyl butyl acrylate maleic anhydride copolymer, styrene methyl acrylate maleic anhydride copolymer, styrene vinyl methyl ether acrylic acid copolymer or styrene butadiene acrylic acid copolymer A method of manufacturing an electrophotographic one-component toner. The method for producing an electrophotographic one-component toner according to claim 1, wherein the coupling agent is silane or titanate. The silane coupling agent according to claim 3, wherein the silane coupling agent is isobutyltrimethoxysilane, mercaptopropyltrimethoxysilane, aminopropyltriethoxysilane, 3-methacryloxypropyltrimethoxysilane n- (2-aminoethyl ) -3-Aminopropanetrioxysilane, 3-glycidoxypropyltriethoxysilane, n-octyltriethoxysilane, 3-chloropropyltriethoxysilane, n- (2- (vinylbenzylimino)- A process for producing an electrophotographic one-component toner, characterized in that it is ethyl) -3-aminopropyltrimethoxy-silane or vinyltriacetoxysilane. The titanate-based coupling agent according to claim 3, wherein the titanate coupling agent is isopropyl-triisostea royl titanate, isopropyl-tridodecylbenzenesulfon titanate, isopropyl-tris (dioctylpyrophosphate) titanate, tetraiso Propyl-bis (dioctylphosphate) titanate, tetraoctylbis (ditridecylphosphate) titanate, tetra (2,2-diaryloxy-methyl-1-butyl) bis (di-tridecyl) phosphate, bis ( Dioctylpyrophosphate) oxy-acetate titanate, bis (dioctylpyrophosphate) ethylene titanate, isopropyl methacryl- octanol titanate, isopropyl dimethacryl-isostearol- titanate, isopropyl- Isostearol-diacrylitanate, isopropyl-tri (dioctylphosphate) titanate, isopropyl-tricumylphenyl titanate, isopropyltri (n-aminoethyl, aminoethyl) titanate And dicumylphenyloxyacetate titanate or diisostearoylethylene titanate. 2. The method for producing an electrophotographic one-component toner according to claim 1, wherein the throughput of the coupling agent is 0.1 to 4 parts by weight based on the magnetic material. 7. The method for producing an electrophotographic one-component toner according to claim 6, wherein the throughput of the coupling agent is 0.5 to 1 parts by weight based on the magnetic material.