JPS59170855A - Encapsulated toner for developing electrostatic latent image - Google Patents

Abstract

PURPOSE:To obtain a toner prevented from peeling off an outer shell from a core material, superior in durability, and suitable especially for pressure fixation by forming the first outer shell of double outer shells consisting of the core material, the first shell, and the second shell, with an epoxysilane coupling agent. CONSTITUTION:The particles of a core material contg. PE having >=0.94sp. gr. and paraffin wax (further contg. a magnetic powder in the case of a magnetic toner) is immersed into a water-methanol soln. of an epoxysilane coupling agent, then filtered and dried to form the first outer shells. These particles are dispersed into an org. solvent soln. of e.g., a dimethylaminoethyl methacrylate- styrene copolymer, and then, water is added to phase separate and ppt. the polymer on the first shells. They are taken out, washed with water, and dried to form the second shells. The encapsulated toner thus obtained is prevented from oozing out of the core material to the surface, and peeling off the outer shells, and superior in pressure fixability and durability.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a toner used to develop an electrical latent image in electrophotography or electrostatic printing, and particularly to a capsule toner suitable for pressure fixing. .

Conventionally, as an electrophotographic method, U.S. Patent No. 2,297,69
Although many methods are known, as described in Japanese Patent Publication No. 1, Japanese Patent Publication No. 42-23910, and Japanese Patent Publication No. 43-24748, etc., they generally utilize photoconductive substances and perform various methods. After forming an electrical latent image on the photoreceptor by means of means, developing the latent image with toner and transferring the toner image to a transfer material such as paper as necessary, applying heat, pressure or solvent vapor. It is used to fix the image and obtain copies.

Various developing methods are also known for visualizing electrical latent images using toner, and these can be broadly classified into dry developing methods and wet developing methods. The former further includes a method using a two-component developer;
It is divided into two methods: a method using a one-component developer;

Among the two-component developing methods, widely used methods include a magnetic brush method using an iron powder carrier and a cascade method using a bead carrier, depending on the type of carrier for transporting the toner. All of these methods are excellent methods that can produce good images relatively stably, but on the other hand, they suffer from the common drawbacks associated with two-component developers, such as carrier deterioration and image fluctuations due to fluctuations in the toner and carrier mixing ratio. have

In order to avoid these drawbacks, various development methods using a one-component developer consisting only of toner have been proposed, and among them, many excellent methods using magnetic toner have been put into practical use. A developing method that uses a magnetic one-component developer is the MagneDry method that uses conductive toner, but although this is stable for development, it has poor transferability on transfer materials such as plain paper. There's a problem.

Therefore, as a method using a high-resistance magnetic toner with good transferability, there is a method using dielectric polarization of toner particles as disclosed in JP-A-52-94140, and a method of charge transfer by toner disturbance as disclosed in JP-A-53-31136. etc., but there is a problem with the stability of development. In addition, as an excellent developing method recently proposed by the present applicant, Japanese Patent Application Laid-Open No. 54-42141,
A method of developing a latent image by flying toner particles as disclosed in Japanese Patent Application Laid-Open No. 55-18656 has been put into practical use.

This is done by applying a very thin layer of magnetic toner onto the sleeve.
This is triboelectrically charged, and then under the action of a magnetic field, it is brought very close to the electrostatic image and opposed to it without contacting it to develop it.

According to this method, by applying an extremely thin layer of magnetic toner onto the sleeve, the chances of contact between the sleeve and toner are increased, and sufficient frictional electrification is possible.The toner is supported by magnetic force, and the magnet and toner are connected. By moving the toner particles relative to each other, the agglomeration of the toner particles is released, and the toner particles are sufficiently rubbed against the sleeve, and the toner is supported by magnetic force and developed by facing the electrostatic image without coming into contact with it. By preventing such problems, excellent images can be obtained.

The most common method for fixing the developed toner image is to heat it with an infrared heater or a heated roller, and fuse it to the support to solidify it. There is a shift to a pressure fixing method using rigid rollers.

Toner materials are selected to suit each fixing method, and toners used in a particular fixing method generally cannot be used in other fixing methods. In particular, it is impossible to reuse toner for thermal fixation using an infrared heater as toner for thermal roller fixation, and furthermore, there is almost no compatibility between toner for thermal fixation and toner for pressure fixation. Therefore, toners suitable for each fixing method have been researched and developed, and toners for one-component pressure fixing methods have been further improved. The method of fixing toner by applying pressure has the following advantages: there is no risk of burning the copy sheet, copying can be done without waiting time when the copier is turned on, high-speed fixing is possible, and the fixing device is simple. There are many advantages such as

For such toners that can be fixed under pressure, it is necessary for the constituent resin to have properties suitable for pressurization, and resins suitable for this purpose are actively being developed. However, it has excellent pressure fixing properties, does not cause offset to the pressure roller, and has stable development and fixing performance even after repeated use, and does not cause adhesion to the carrier, metal sleeve, or photoreceptor surface. However, a practical pressure fixing toner with good storage stability that does not aggregate or form cakes during storage has not been obtained.

In particular, problems remain in the fixability to plain paper in terms of pressure fixability.

Various capsule-type toners having hard resin shells have also been proposed. For example, Special Publication No. 54-8104, Special Publication No. 5
There are capsule toners with a soft material core as seen in No. 1-35867, and capsule toners with a soft resin solution core as shown in JP-A-51-132838, but they suffer from problems such as insufficient pressure fixing ability and offset phenomenon. There are many unresolved issues,
It has not yet been put into practical use.

Furthermore, in the capsule toner described above, the adhesion between the core material and the shell material is weak, and the shell tends to peel off in some parts, resulting in instability of charge control, changes in image quality and image density, etc. in durability tests, etc. Problems such as fusion on the developer sleeve and on the photoreceptor surface arise. In addition, methods for encapsulating capsule toner include a phase separation method from an organic solution system, an interfacial precipitation method, and a spray drying method.Many of these methods involve dissolving a resin material serving as a shell material in an organic solvent in which the core material is insoluble. Encapsulation is performed after the core material is dispersed in the solution. However, with a core material containing a low molecular weight resin, it is difficult to completely prevent the core material from leaching into an organic solution, and when encapsulated, the properties of the obtained toner are significantly reduced. . In addition, in these encapsulation methods, the organic solvent is selected from those in which the core material is insoluble and the shell material is soluble, and at the same time, excessive restrictions are placed on the core material, shell material, and encapsulation conditions. be.

SUMMARY OF THE INVENTION An object of the present invention is to compensate for the above-mentioned drawbacks, to provide a capsule toner in which the core material and shell material do not peel off, and which has excellent durability.

Another object of the present invention is to provide a capsule toner that can easily prevent the dispersion of the core material in the encapsulation process and the elution of the core material into the organic solution during encapsulation.

Furthermore, it is an object of the present invention to provide a capsule toner that can reduce restrictions on the core material, shell material, organic solvent used, and encapsulation conditions during encapsulation.

A further object of the present invention is to provide a low-pressure fixing capsule toner that has good fixing properties on plain paper at a lower pressure than conventional ones.

A further object of the present invention is to provide a capsule toner with excellent charge controllability, developability, and transferability.

The present invention provides a capsule toner having a multilayer structure consisting of a first wall and a second wall, wherein the first wall of the capsule toner is composed of an epoxy silane coupling agent. It is in the microcapsule toner that develops.

As the resin constituting the core material used in the present invention, polyethylene and paraffin wax having a density of 0.94 g/cm 3 or more are suitable. The polyethylene with a density of 0.94 g/cm3 or more is particularly preferably one with a melt viscosity of 600 CPS or less at 140°C, and is known as a so-called low molecular weight polyethylene or polyethylene wax. It is manufactured.

Melt viscosity is 600CPS or less and density is 0.94g
For example, commercially available polyethylenes with a particle size of /cm3 or more include AC polyethylene +9 (manufactured by Allied Chemical Co., Ltd.) (0
．． 94g/cm3, 350CPS) High Wax 31
0P (Mitsui Petrochemical) (0.94g/cm3, 250
CPS) 410P (Mitsui Petrochemical) (
0.94g/cm3, 550CPS) High Wax 4
05P (Mitsui Petrochemical) (0.96g/cm3, 55
0CPS) 〃 400P (manufactured by Mitsui Petrochemical)
(0.97g/cm3, 550CPS), etc. 15
Examples of materials with a density of 0.94 g/cm3 or higher with a density of 0 CPS or lower are as follows.

Hiwax 200P (Mitsui Petrochemical) (0.97
g/cm3, 70CPS) Hoechst Wax PE130 (manufactured by Hoechst AG) (
0.95g/cm3, 117CPS) Paraffin waxes include those shown in the following table.

Paraffin wax and microwax (manufactured by Nippon Oil) In the present invention, the above density 0.94 g/cm3
The above polyethylene and paraffin wax are used in appropriate combination. Of course, you may combine several types of paraffin wax as necessary.

The blending ratio of the polyethylene and paraffin wax is preferably 8/2 to 0.5/99.5, more preferably 6/4 to 1/9 by weight.

In addition to the above-mentioned polyethylene and paraffin wax, the resin constituting the core material of the present invention may be mixed with a polymer having a hydroxyl group, such as polyvinyl alcohol, cellulose, methyl cellulose, ethyl cellulose, hydroxyethyl cellulose, carboxymethyl cellulose, starch, carboxylic acid, etc. There are water-soluble polymers such as methyl starch and dialdehyde starch, and the amount thereof added is from 0.1 to 20% by weight of the total resin in the core material.

As the coloring agent for the core substance of the capsule toner of the present invention, known dyes and pigments can be used. Examples include various carbon blacks, aniline black, naphthol yellow, molybdenum orange, rhodamine lake, alizarin lake, methyl violet lake, phthalocyanine blue, nigrosine methylene blue, rose bengal, and quinoline yellow.

Further, when the capsule toner of the present invention is used as a magnetic toner, magnetic powder can be contained in the core material. The magnetic powder includes ferromagnetic elements and alloys and compounds containing these elements, including alloys and compounds of iron such as magnetite and ferrite, cobalt, nickel, manganese, etc. This magnetic powder may also be used as a coloring agent. The content of this magnetic powder is preferably 15 to 70 parts by weight based on 100 parts by weight of all the resins in the core material.

The epoxysilane coupling agent used in the present invention is a silane compound having an epoxy group as a functional group, and commercially available ones include γ-glycidoxypropyltrimethoxysilane, β-(3,4- epoxycyclohexyl)ethyltrimethoxysilane, γ-glycidoxypropyldimethylethoxysilane, γ-glycidoxypropylmethylethoxysilane (both U.S. PET
(manufactured by RARCH SYSTEMS).

The epoxy silane coupling agent is used after being dissolved in distilled water or a solution of water and alcohol, and its concentration is preferably 0.1 to 10% by weight.

Further, as the outer shell resin of the second wall, for example, monopolymers of styrene and its substituted products such as polystyrene, polyP-chlorostyrene, and polyvinyltoluene, styrene-P-chlorostyrene copolymers, styrene-propylene copolymers, etc. Copolymer, styrene-vinyltoluene copolymer, styrene-vinylnaphthalene copolymer, styrene-methyl acrylate copolymer, styrene-ethyl acrylate copolymer, styrene-butyl acrylate copolymer, styrene-octyl acrylate copolymer, styrene-methyl methacrylate copolymer, styrene-ethyl methacrylate copolymer, styrene-butyl methacrylate copolymer, styrene-α-methyl chloromethacrylate copolymer, styrene-acrylonitrile copolymer, Styrene-vinyl methyl ether copolymer, styrene-vinyl ethyl ether copolymer, styrene-vinyl methyl ketone copolymer, styrene-butadiene copolymer, styrene-isoprene copolymer, styrene-acrylonitrile-indene copolymer , styrene-
Styrenic copolymers such as maleic acid copolymers, styrene-maleic ester copolymers, polymethyl methacrylate, polybutyl methacrylate, polyvinyl chloride,
Polyvinyl acetate, polyethylene, polypropylene, polyester, polyurethane, polyamide, epoxy resin,
Polyvinyl butyral, polyamide, polyacrylic acid resin, rosin, modified rosin, terpene resin, phenol resin, aliphatic or alicyclic hydrocarbon resin, aromatic petroleum resin, salt, etc. can be used alone or in combination.

Further, an appropriate amount of a charge control agent such as a metal-containing dye or nigrosine conventionally used in toners may be added to the outer shell resin.

In the present invention, methods for encapsulating the second wall include a phase separation method from an organic solvent system, an interfacial precipitation method, a spray drying method, and the like, and these methods can be used as appropriate.

The core material used in the present invention is manufactured, for example, as follows.

Paraffin wax 155 (manufactured by Nippon Seiro) 66 parts by weight,
Hiwax 200P (manufactured by Mitsui Petrochemical) 33 parts by weight,
When 60 parts by weight of magnetite was melted and mixed at 150°C, granulated with a spray dryer, and then classified with a dry classifier, the number average particle diameter was 8.64μ, 29% below 6.35μ (number distribution) 2% above 20.2μ. (Volume distribution) [Using a Coulter counter with a 100μ aperture] Core material is obtained.

Example 1 100 g of the above-mentioned core material was dispersed in 300 cm of a 2% by weight water-methanol (weight ratio 10/90) solution of γ-glycidoxypropyltrimethoxysilane, and then filtered to give 60 g of the core material.
℃ for 1 hour, crushed in a coffee mill, and the first
The walls were covered. Core material 4 that formed this first wall
0g was converted into 2g of dimethylamine ethyl methacrylate-styrene copolymer (molar ratio of both 1/9) using a phase separation method.
A second wall was formed. The obtained dispersion was filtered, washed with water, and dried at 50°C for 24 hours. The surface of the obtained toner was observed using an electron microscope, and the surface layer was densely covered with resin and had a smooth surface, and there was no peeling of the shell material. It was confirmed that encapsulation had taken place. 9 g of iron powder (200 to 300 mesh) was mixed with 1 g of this toner, and the amount of triboelectric charge was measured using a known measuring method: +24.0 μc
/g.

Next, 0.12 g of hydrophobic colloidal silica (trimethylmethoxysilane treated product manufactured by Nippon Silica Industries, trade name: EK150) was added to 30 g of this toner to obtain a developer. The amount of triboelectric charge was +21.3 μc/g.

This toner was applied to a developing machine having a magnetic sleeve to develop a latent image with a negative electrostatic charge, which was then transferred onto high-quality paper. When the transfer paper carrying the image was passed through a pressure fixing device consisting of two pressure rollers that can apply pressing force from both ends, it was transferred at a speed of 125 mm/sec to produce 10 kg/
Almost perfect fixing performance was exhibited at a linear pressure of cm.

The image density was 1.3, and a clear reversed image with no fog was formed, which was good. Furthermore, after an 8-hour idling durability test in the developing machine, the image was printed again, but the image density was 1.5, the amount of triboelectric charge was 22.0 μc/g, and the image quality did not change. Excellent durability was observed. Furthermore, when the surface of the toner was observed using an electron microscope, there was no peeling of the walls at all.

Example 2 100 g of the above core material was mixed with 1% by weight of β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane in water.
After dispersing in 300 cm3 of ethanol (weight ratio 5/90) solution, the first wall was formed on the core material by the same method as in Example 1, and then 40 g of the core material was mixed with diethylamine ethyl methacrylate-styrene by a spray drying method. The second wall was formed with 2 g of the copolymer (molar ratio of both: 1/9). The amount of triboelectric charge of the obtained toner was +22.0μ
c/g.

When this capsule toner was processed and imaged in the same manner as in Example 1, a clear image with an image density of 1.2 and no fog was obtained. Also, in the durability test, similar good results as in Example 1 were obtained.

Claims (1)

[Scope of Claims] 1. A capsule toner having a multilayer structure consisting of a core material, a first wall, and a second wall, characterized in that the first wall of the capsule toner is composed of an epoxy silane coupling agent. A capsule toner that develops an electrical latent image. 2. The capsule toner for developing an electrical latent image according to claim 1, wherein the core material contains polyethylene having a density of 0.94 g/cm3 or more and paraffin wax. 3. Claim 1 or 3, characterized in that the second wall is composed of a copolymer of a monomer having a tertiary amine and one or more other monomers. A capsule toner that develops the electrical latent image according to item 2. 4. The electrical potential according to claim 1, 2, or 3, characterized in that the core substance contains a polymeric substance having hydroxyl groups in an amount of 0.1 to 20% by weight. Capsule toner that develops images.