JPH03113462A - Manufacture of electrostatic charge developing toner - Google Patents

Abstract

PURPOSE:To easily obtain a toner having a narrow size distribution without requiring a specified process by adding a coplymer made from a small amount of oil-solubel monomer and sodium styrenesulfonate. CONSTITUTION:The copolymer to be used as a dispersion stabilizer is obtained by copolymerizing at least one of the oil-soluble monomers selected from vinyl aromatic hydrocarbon monomers and (meth)acrylate, with the sodium styrenesulfonate and it has a weight average molecular weight of 1.0X10<3> - 1.0X10<6>. If the copolymer is smaller than this range, the dispersion stability effect is reduced and it is higher than this range dissolution of this copolymer in the polymerizable monomers to be made difficult, and accordingly, the toner narrow in the size distribution to be obtained without any particular process.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a method for producing an electrostatic charge developing toner, and more particularly to a method for producing an electrostatic charge developing toner having a focused particle size distribution.

(Prior art) For example, to synthesize a black toner using a suspension polymerization method,
A common method is to mix and disperse carbon black in a monomer and then carry out suspension polymerization. However, carbon black tends to aggregate in monomers, so simply adding carbon black to monomers and mechanically mixing and dispersing them will not disperse carbon black uniformly in monomers. You can't get the same toner.

Conventionally, in order to improve the dispersibility of carbon black in a monomer, for example, the following prior art has been proposed.

■ JP-A-59-52253 ■ JP-A-60-117253 ■ JP-A-56-116088 ■ JP-A-60-243664 The techniques disclosed in the above ■ and ■ are silane-based cups. The dispersibility of carbon black is improved by surface-treating carbon black using a ring agent or a titanium-based coupling agent.

The technique disclosed in (2) is a method in which a monomer is subjected to blur polymerization in the presence of carbon black, and a polymer is graph-polymerized on the surface of carbon black particles.

The polymerization rate at this time is 10% or less, and as the polymerization rate increases, the viscosity increases and workability decreases. The technique disclosed in (2) is the same as the technique (2) above, in which the carbon black is dried before the grafting treatment.

(Problems to be Solved by the Invention) It has been found that in the techniques disclosed in (1) and (2) above, the dispersibility of carbon black in monomers is hardly improved even if a silane coupling agent or a titanium coupling agent is used. Ta.

In the techniques disclosed in ■ and ■ above, not only are the operations extremely complicated, but when prepolymerizing monomers in the presence of carbon black, polymers that do not contribute to the stability of the carbon black are also produced. The presence of this polymer increases the viscosity of the monomer layer and broadens the particle size distribution of the droplets formed in the subsequent suspension operation. Therefore, there is a drawback that the obtained toner has a wide particle size distribution.

The present invention has been made in view of the above-mentioned drawbacks, and its purpose is to use a special dispersion stabilizer to produce toner for developing electrostatic images with a relatively narrow particle size distribution. The object is to provide a method that can be manufactured without requiring special steps.

(Means for Solving the Problems) The toner for developing electrostatic images of the present invention contains at least one oil-soluble monomer selected from the group consisting of vinyl aromatic hydrocarbon monomers and (meth)acrylic acid esters. The weight average molecular weight obtained by copolymerizing i-form and sodium styrene sulfonate is 1. The method is characterized in that a colored composition is prepared by mixing a copolymer of OX 103 to 1°0 , thereby achieving the above objective.

The present invention will be explained in detail below.

In the present invention, ff1ffi average molecular ff1 obtained by copolymerizing an oil-soluble monomer and sodium styrene sulfonate
A 1.0X103 to 1.0X106 copolymer is used as a dispersion stabilizer. If the weight average molecular weight of this copolymer is smaller than the above range, the dispersion stabilizing effect will be small.

Further, it is difficult to dissolve a copolymer having a weight average molecular weight larger than the above range in a polymerizable monomer. Moreover, this copolymer is preferably obtained by block or graft polymerization because it improves dispersion stability.

The polymerization method for obtaining the copolymer is not particularly limited, but dispersion polymerization, solution polymerization, and emulsion polymerization are preferred. in this case,
It is preferable to carry out the polymerization in a mixed medium of water and a water-miscible organic solvent, which will be described later, and in the presence of a suitable dispersion stabilizer and a polymerization initiator, which will be described later.

The oil-soluble monomer as a starting material for the copolymer is a vinyl aromatic hydrocarbon monomer or (meth)acrylic acid ester.

The general formula for the vinyl aromatic hydrocarbon monomer is the following formula (
1) are used, specifically styrene,
α-methylstyrene, vinyltoluene, α-chlorostyrene, 0-chlorostyrene, m-chlorostyrene, p-
Examples include chlorostyrene, p-ethylstyrene, and divinylbenzene, and these can be used alone or in combination of two or more.

In the formula, R1 represents a hydrogen atom, a lower alkyl group, or a halogen atom, and R2 represents a hydrogen atom, a lower alkyl group, a halogen atom, an alkoxy group, a nitro group, or a vinyl group.

In addition, as the (meth)acrylic ester, an acrylic monomer whose general formula is represented by the following formula (2) is used,
Specifically, methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, cyclohexyl acrylate, phenyl acrylate, methyl methacrylate, hexyl methacrylate, and 2-methacrylate.
-ethylhexyl, ethyl β-hydroxyacrylate,
γ-propyl hydroxyacrylate, δ-butyl hydrobovine cyacrylate, ethyl β-hydroxymethacrylate,
Examples include ethylene glycol dimethacrylate, tetraethylene glycol dimethacrylate, and the like, and these can be used alone or in combination of two or more.

RcoGHz = C-(:0-0-R4...(2) In the formula, R3 represents a hydrogen atom or a lower alkyl group, and R4 represents a hydrogen atom, a hydrocarbon group having 1 to 12 carbon atoms, hydroxyalkyl group or vinyl ester group.

The composition ratio of the oil-soluble monomer and sodium styrene sulfonate is generally 70:30 to 99:1, particularly 8
It is preferable to use a frffi ratio of 0:20 to 98:2.

The polymerizable monomer used in the present invention is at least one selected from the group consisting of vinyl aromatic hydrocarbon monomers and (meth)acrylic acid esters, and is used as the oil-soluble monomer. You can use whatever you have.

The above coloring agents include pigments and dyes, such as carbon black; insoluble azo pigments (obtained by diazo coupling of aromatic amines) such as Fast Yellow, Disazo Orange, and Naphthol Red; phthalocyanine-based pigments such as copper phthalocyanine. Pigments; Dyeing lakes such as Fanard lake, tannin lake, and katanol; Isoindolino pigments such as Isoindolino Erotic Greenish and Isoindolino Erol Dessini; Quinacridone pigments; Perylene pigments such as Perylene Scarlet and Berylene Maroon Pigments; etc.

A colored composition is obtained by mixing the copolymer, a polymerizable monomer, and a coloring agent. The amount of the copolymer added is preferably 2.5 parts or less per 5 parts by weight of the colorant, and 0.
．． 1 to 2.0 Ilt parts is more preferred. Conventionally known waxes and charge control agents are added to this coloring composition as necessary.

Since this coloring composition contains a relatively high molecular weight copolymer as a dispersion stabilizer, the colorant such as carbon black can be uniformly dispersed in the monomer by the commonly performed stirring operation. Become. This is because the copolymer into which sodium sulfonate groups have been introduced has polar groups on the surface of the colorant (
This is thought to be due to strong adsorption to hydrophilic groups (such as hydroxyl groups).

Next, this colored composition is subjected to suspension polymerization to obtain the electrostatic image developing toner of the present invention. Suspension polymerization can be carried out according to conventional methods. As a dispersion stabilizer during suspension dispersion,
Dispersion stabilizers used in g-turbidity polymerization that are known per se can be used, but inorganic dispersants are preferred from the viewpoint of particle stability and ease of removal from polymer particles after polymerization, especially poorly water-soluble inorganic salts. Fine powder is used. Specifically, calcium sulfate, tricalcium phosphate, magnesium carbonate, barium carbonate, calcium carbonate, aluminum hydroxide, perilla, etc. can be mentioned. The amount of dispersant used is o,oot to 10 parts by weight, especially o,oo to 100 parts by weight of water.
It is preferable to use about 5 parts by weight.

As a polymerization initiator, azo compounds such as azobisisobutyronitrile, cumene hydroperoxide, t-butyl hydroperoxide, dicumyl peroxide, di-t-
Examples include peroxides such as butyl peroxide, benzoyl peroxide, and lauroyl peroxide, and those soluble in the above monomers are particularly preferred.

In addition, combinations of 7-rays, ionizing radiation such as accelerated electron beams, ultraviolet rays, and various photosensitizers can also be used.

The amount of these polymerization initiators may be the amount commonly used (generally preferably 0.1 to 10% by weight based on the monomers charged).The polymerization temperature and time are generally 1 to 1% by weight at a temperature of 40 to 100°C 50 hours is appropriate.The reaction system should be stirred gently so that a homogeneous reaction occurs as a whole, and the reaction system should be replaced with an inert gas such as nitrogen to prevent polymerization from being inhibited by oxygen. Preferably, polymerization is carried out.

The particle size of the toner produced by this polymerization is generally 0, 1~
10 g ra %, especially 0.5 to 7 μm, and the particle size distribution of the toner is relatively uniform and narrow. Since the toner is obtained in the form of granules having the above particle size range, the produced particles are filtered, optionally washed with water or a suitable solvent, and dried to obtain the toner.

(Example) Hereinafter, the present invention will be specifically explained based on Examples.

Dai JLLL Dissolve 20 g of polymethacrylic acid in a mixed medium of 1350 g of methanol and 36 g of water, and add 180 g of styrene to this.
Add 20 g of sodium styrene sulfonate and 4 g of azobisisobutyronitrile, and stir at 150 rpm under a nitrogen atmosphere in a 3-liter separable flask.
The reaction was carried out at 0°C for 12 hours to complete the polymerization. This emulsion was centrifuged to separate particles to obtain a white powder. This styrene-styrene sulfonic acid
-As a result of measuring the weight average molecular weight of the IJum copolymer by GPC, the weight average molecular weight ffi (My) was 8.7X
It was 105.

After dissolving 25 parts of the styrene-sodium styrene sulfonate co-ffi combination synthesized in the above method in 60 parts of styrene, 5 parts by weight of carbon black (MA-100 manufactured by Mitsubishi Kasei) was added and dispersed by ultrasonication. Dispersion treatment was carried out using a machine for 10 minutes. When this dispersion was observed under an optical microscope, it was found that the carbon black was dispersed to a size of about 1 μm or less.

Into this dispersion were further dissolved 0.5 parts by weight of Subiron Black TRH (manufactured by Odugaya Chemical Industry Co., Ltd.) as a charge control agent and 4 parts by weight of azobisisobutyronitrile as a polymerization initiator. This was added to 500 parts by weight of water (pH 11) in which 2% tertiary calcium phosphate was dissolved, and suspended and dispersed using a TK-Homo mixer (manufactured by Tokushu Kika Kogyo Co., Ltd.), and then heated at 80°C under a nitrogen stream. The mixture was stirred normally and polymerized for 5 hours. This was filtered, washed and dried to obtain a toner.

When the particle size distribution of the obtained toner was measured using a coal counter, the volume average was 1000 μm, and the amount of fine powder toner of 5 μm or less was 0.5% or less. This toner and ferrite carrier were mixed and stirred to obtain a developer, and when the band T1m of the developer was measured by a blow-off method, it was -20 μC/g. When this developer was mounted on DC-1205 manufactured by Sanda Kogyo Co., Ltd. and images were evaluated, the image density of solid black was 1.4 or higher.

Jitan LLL Dissolve 20 g of polyacrylic acid in a mixed medium of 1350 g of isopropyl alcohol and 36 g of water, add 180 g of methyl methacrylate, 20 g of sodium styrene sulfonate and 4 g of azobisisobutyronitrile to make 3 liters of separable 15 in a flask under a nitrogen stream
While stirring at 0 rpm, react at 60'C for 12 hours.
Polymerization was completed. This emulsicon was centrifuged to separate particles and a white powder was obtained.

As a result of measuring the fIfi average molecule m of this methyl methacrylate-sodium styrene sulfonate co-tetramer by GPC, the ff1ffi average molecule ffi (My) was 2.
．． It was 2X 105.

After dissolving 0.21 ffi parts of the methyl methacrylate-sodium styrene sulfonate copolymer synthesized by the above method in 60 fi fi parts of methyl methacrylate, 5 fflffi parts of phthalocyanine blue was added and dispersed for 10 minutes using an ultrasonic dispersion machine. did. When this dispersion was observed under an optical microscope, it was found that the pigment was dispersed to a size of about 1 μm or less.

This dispersion was further added with Pontron E8 as a charge control agent.
4 (manufactured by Hodugaya Chemical Industry Co., Ltd.) and 4 parts by weight of azobisisobutyronitrile as a polymerization initiator were dissolved. This was added to 500 parts by weight of water (p old 1) in which 2% of tertiary calcium phosphate was dissolved and suspended and dispersed using a TK-Homo mixer (manufactured by Tokushu Kika Kogyo ■). Polymerization was carried out for 5 hours with normal stirring at 'C. This was filtered, washed and dried to obtain a toner.

When the particle size distribution of the obtained toner was measured using a call counter, the volume average was 11.5 μm, and the amount of fine powder toner of 5 μm or less was 0.5% or less. This toner and ferrite carrier were mixed and stirred to obtain a developer, and when the band "lff1" of the developer was measured by the blow-off method, it was -20 μC/g. When an image was formed on an OHP film by mounting the film on an OHP film, it showed sufficient translucency.

Carbon black (MA-100 manufactured by Mitsubishi Kasei Co., Ltd.) is added to 6 parts by weight of styrene that does not contain any mosquito-repelling and dispersion stabilizers.
5 parts by weight were added and dispersed for 10 minutes using an ultrasonic disperser. When this dispersion was observed under an optical microscope, it was found that almost no carbon black was dispersed, and aggregates of 10 μm or more were observed.

Into this mixture of carbon black and styrene, 0.5 parts by weight of Subiron Black TRH (manufactured by Hodogaya Chemical Industry Co., Ltd.) as a charge control agent and 4 parts by weight of azobisisobutyronitrile as a polymerization initiator were dissolved. .

This was mixed with water in which 2% of tertiary calcium phosphate was dissolved (pH
11) Pour into 500 parts by weight and add to TK-Homo mixer (
After suspending and dispersing the mixture using a suspension (manufactured by Tokushu Kika Kogyo Co., Ltd.), normal stirring was carried out at 80° C. under a nitrogen stream, and polymerization was carried out for 5 hours.

This was filtered, washed and dried to obtain a toner.

When the obtained toner was observed under an optical microscope, it was found that there were many particles that did not contain any carbon black.

When the particle size distribution of this toner was measured using a coal counter, it was found that the volume average was 12.5 μm, and about 20% of the particles were 2° μm or more, indicating that the particle size distribution was extremely wide. This toner and ferrite carrier are mixed and stirred to obtain a developer, and a developer band 7 is obtained by a blow-off method.
When 4ffi was measured, it was found to be -18 μC/g, which was a sufficient value.
5 and evaluated the images, problems such as scattering and fogging occurred.

(Effects of the Invention) According to the present invention, by adding a small amount of a copolymer consisting of an oil-soluble monomer and sodium styrene sulfonate, the dispersion stability of a colorant such as carbon black to a polymerizable monomer can be improved. It is possible to obtain a toner for developing an electrostatic image with a narrow particle size distribution, and this toner has the advantage of not having problems such as scattering or smudging.

that's all

Claims (1)

[Claims] 1. The weight average molecular weight obtained by copolymerizing at least one oil-soluble monomer selected from the group consisting of vinyl aromatic hydrocarbon monomers and (meth)acrylic acid esters and sodium styrene sulfonate is 1. .0×10^3~1.
A static method characterized by preparing a colored composition by mixing a 0x10^6 copolymer, a polymerizable monomer, and a coloring agent, and then carrying out suspension polymerization using this colored composition. Method for producing toner for charge development.