JPS58211165A - Microcapsule toner for electrophotography - Google Patents

Abstract

PURPOSE:To improve fixability by breaking the capsule walls of a microcapsule toner to powder in the stage of press fixing and to obtain a picture image which is high in density and maintains the density without decreasing against friction or the like, by dispersing fine inorg. powder in the form of matrix into the capsule walls of said toner. CONSTITUTION:A mixture of a resin for forming capsule walls and fine powder of silica, alumina, CaCO3 or the like having 1-10mu grain sizes at a rate of 1-90% of the resin is used in the stage of manufacturing a microcapsule toner. In the stage of press fixing, the capsules are broken easily to the fine powder, and the broken wall materials are so smaller in volume than the core material that said materials are taken into the core material for fixing; therefore, the picture image of high density is obtd. without spoiling the fixability and without the stripping of the toner when the fixed image is rubbed.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a toner for electrophotographic development, particularly for two-component magnetic brush development. Conventional electrophotographic methods include U.S. Patent No. 2297691 and Japanese Patent Publication No. 42-2391.
Various methods are described in Japanese Patent Publication No. 43-24748 and Japanese Patent Publication No. 43-24748, but in all of these methods, charges are uniformly applied to the photoconductive layer, and an original is printed on the photoconductive layer. A latent image is formed by being irradiated with a corresponding light image, and then the latent image is developed with black powder toner to become a visible image. If necessary, it is transferred to paper or the like, and then it is exposed to heat, pressure, etc. It will be permanently fixed.

Conventional electrophotographic toners are generally made by melting and kneading resin and pigment, which are toner binders, and then cooling and pulverizing the mixture.
By classifying as necessary, toner having a desired particle size was obtained. However, the surface of the toner obtained by this manufacturing method has parts covered with resin and parts where the pigment is exposed, and the surface properties are uneven, so the distribution of the friction zone NR of the toner is not uniform. In addition, when toners are made using resins with low softening points or melting points as binders in order to improve fixing properties, the toner fluidity becomes extremely poor, resulting in drawbacks such as impossibility of practical use.

USP3788 is a solution to improve these drawbacks.
As disclosed in Japanese Patent No. 994, there are toners in which the periphery of a soft core material is coated with another hard resin, but when such toners are fixed in a fixing device, the capsule wall ruptures and the core material is exposed to the surface. However, since the capsule wall exists between the core material and the member to be fixed, there is a drawback that the fixing performance is weakened.

SUMMARY OF THE INVENTION An object of the present invention is to provide a microcassicle toner that overcomes the above-mentioned drawbacks.

The objects of the present invention are achieved in a microcapsule toner. Here, the term "matrix-like" refers to a state in which the inorganic fine powder is dispersed in the form of islands within the capsule wall. The inorganic fine powder may be exposed on the surface of the capsule wall or embedded in the resin, but is preferably uniformly distributed in the thickness direction of the wall.

Inorganic particles having a particle size of 1 μm to 10 μm can be used. The mixing ratio of inorganic fine powder is 1 to 90% of the wall forming material.
It can be added, but preferably 5 to 10% 1. That is, when the toner of the present invention is developed on a photoreceptor in a general development process, transferred to paper and passed through a fixing device, pressure is applied to the coating layer. When the coating layer is destroyed, the stress concentration between the IJ sock material and the resin that forms the coating layer causes the walls of the incompatible cells to be destroyed into powder.

Since the broken wall-forming material powder is very small compared to the volume of the capsule core material, it is absorbed into the heat-melted or pressure-fixed core material without impairing the fixing properties.

Examples of cuff cell core materials that can be used in the present invention include the following. Polystyrene, chloropolystyrene, poly-α-methylstyrene, styrene-chlorostyrene copolymer, styrene-zolopyrene copolymer, styrene-butadiene copolymer, styrene-vinyl chloride copolymer, styrene-vinyl acetate copolymer, Styrene-maleic acid copolymer, styrene-acrylic acid ester copolymer (styrene-methyl acrylate copolymer, styrene-ethyl acrylate copolymer, styrene-butyl acrylate copolymer, styrene-octyl acrylate copolymer) polymers, styrene-phenyl acrylate copolymers, etc.), styrene-
Methacrylic acid ester copolymers (styrene-methyl methacrylate copolymer, styrene-ethyl methacrylate copolymer, styrene-butyl methacrylate copolymer, styrene-phenyl methacrylate copolymer, etc.), styrene-α
- Methyl chloroacrylate copolymer, styrene-acrylonitrile-acrylic acid ester copolymer, etc.
V-based resins (monopolymers or copolymers containing styrene or styrene substitutes) vinyl chloride resins, styrene-vinyl acetate copolymers, rosin-modified maleic acid resins, phenyl resins, epoxy resins, polyester resins, low molecular weight polyethylene , low molecular weight polypropylene, ionomer resin,
Polyurethane resin, ketone resin, ethylene-ethyl acrylate copolymer, xylene resin, polyvinyl butyral, inorganic fine powders that can be used in the present invention include silica, alumina, zinc oxide, calcium carbonate, tin oxide, kaolin, clay, Calcium fluoride, dolomite, talc, alumina white, mica powder, aluminum sulfate, barium sulfate, calcium sulfate, asbestos, pumice powder, graphite, glass fiber, and any other material that is incompatible with the wall forming material may be used.

As the encapsulation method of the present invention, a phase separation method, a spray dryer method, an air suspension method, etc. can be applied.

Example 1 Mikata High Wax 405MP (K
.

(manufactured by Columbia Co., Ltd.) and 5 parts of Raven 3500 (manufactured by Columbia Co., Ltd.) were kneaded in a roll mill.

25 parts by weight of this mixture and 40 parts by weight of toluene were placed in a magnetic beer mill pot and stirred with a stainless steel ball for 24 hours to obtain a suspension in which polyethylene wax with a particle size of 8 to 12 μm was dispersed in toluene. . This is called suspension A.

Separately, 20 parts by weight of fCD-125 (Esso standard polystyrene resin) and R972 (manufactured by Nippon Aerosil Co., Ltd. 51
02) Suspension B is obtained by dispersing 10 parts by weight of 10 parts by weight (5 parts by weight) in a magnetic ball mill pot for 24 hours.

Suspension At00 heavy i section and suspension B5
A capsule toner having a wall (silica dispersed in polystyrene) around polyethylene wax was obtained by spray drying 0 parts by weight and 100 parts by weight of toluene using a spray dryer (Niro Co., Ltd.). For comparison, a capsule toner was obtained in exactly the same manner as in Example 1, except that Suspenselon B without silica was used.

The toner of Example 1 and iron powder EFV 250/400 mesh (manufactured by Nippon Iron Powder) were mixed at a weight ratio of 5=95 to form NP-6.
000 copying machine without passing it through a fixing device, and this image was fixed with a pressure fixing device at a pressure of 30 kg/ltn.Similarly, a toner image for comparison was also produced using the same pressure fixing device with the same fixing pressure. It took hold.

When a fixing test was conducted by rubbing the above two image zangles 30 times with a crockmeter equipped with sand and poppy rubber, it was found that the microcapsule toner of the present invention had a reduction rate of image density of 20 degrees, whereas that of the comparative example. 40% using toner
@Example 2 AC polyethylene 1702 (manufactured by Allied Chemical Co., Ltd.) 1
00 parts by weight of magnetic material M-3L (Toda Kogyo) 100 parts by weight were kneaded in a heated roll mill, and 30 parts by weight and 50 parts by weight of tetrahydrofuran were dispersed in a ball mill pot to obtain a suspension of tetrahydrofuran with a particle size of 5 to 15 μm. the law of nature. This suspension is made of suspension (manufactured by Asahi Dow Chemical Company) 2Otit part and titanium oxide (Titanium oxide).
umoxide) P 25 (manufactured by Nippon Aeronol Co., Ltd.)
Suspension D is prepared by kneading 10 M parts of the above suspension in a ball mill.

Suspension c 100 M Nobube (!: Part of The Suspension D50iJi and 100 parts by weight of tetrahydrofuran were stirred in a beaker using a groper stirrer, and ion-exchanged water was added dropwise at a rate of 10 q using B-Red. around the particles made of polyethylene and magnetic material (
A microcuff 0 cell toner was obtained by depositing an outer wall in which TlO2 was dispersed in Saran.

A microcuff 0 cell toner was obtained under exactly the same conditions as in Example 2, except that suspension D without TlO2 was used for comparison.

Use the above two toners on an NP-120 copier (manufactured by Canon).
When the fixing properties were examined using the same method as in Example 1, the density reduction rate was 10 in Example 2, while it was 30% in Comparative Example.

Claims (1)

[Claims] Microcapsule toner for electrophotography 0, which is a microcassicle toner, characterized in that inorganic fine powder is dispersed in a matrix in the capsule wall.