JPS6037471B2 - Electrical latent image toner - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a toner for an electrical latent image used for developing an electrical latent image in electrophotography, electrostatic printing, or the like.

Conventionally, many electrophotographic methods have been known, such as U.S. Pat. An electrical latent image is formed on the photoreceptor by various means using a 3D process, and then the latent image is developed with toner, and if necessary, the toner image is transferred to a transfer material such as paper, and then heated. A copy is obtained by fixing by pressure or solvent vapor.

Methods for visualizing electrical latent images using toner include, for example, the magnetic brush method described in U.S. Pat. No. 2,874,063, the cascade development method described in U.S. Pat. The powder cloud method described above is known.

As toners used in these developing methods, fine powders in which dyes and pigments are dispersed in natural or synthetic resins are used. For example, toner particles are made by dispersing a coloring agent (a Yanase material such as carbon black) in a binder resin such as polystyrene and pulverizing it into particles of about 1 to 30 μm.
It is used as. Such toners are usually mixed with a carrier material such as glass beads, iron powder, or fur and used to develop an electrical latent image. Although these toners are required to have various physical and chemical properties, many of the known toners have several deficiencies as shown below. That is, many toners that are easily melted by heating tend to cake or aggregate during storage or in a copying machine. Many toners have poor triboelectric properties due to environmental temperature changes. In addition, with many toners, the resulting image is degraded due to mutual deterioration of the toner, carrier particle, and photosensitive plate due to collision between one toner particle and one carrier particle and their contact with the photosensitive plate surface due to repeated development due to continuous use. The density changes or the background density increases, reducing the quality of the copy. Furthermore, with many toners, when an attempt is made to increase the density of a copied image by increasing the amount of toner adhering to the surface of a photosensitive plate having a latent image, the background density usually increases, resulting in so-called fog development. Since many of the known toners have one or more of the above defects, there is a constant demand for improved toners, especially from the standpoint of maintenance-free copying machines. It is therefore an object of the present invention to provide a toner having superior physical and chemical properties that overcomes the toner deficiencies mentioned above.

A first object of the present invention is to provide a toner that provides an excellent image and does not degrade the quality of the copied image upon repeated copying.

A second object of the present invention is to provide a toner whose triboelectric properties and flow properties are stable against changes in environmental humidity.

A third object of the present invention is to provide a long-life toner suitable for high-speed copying.

That is, the present invention resides in an electrical latent image toner characterized by containing fine particles of fluororesin in a binder resin containing a silicone resin.

Various commercially available silicone resins can be used as the silicone resin used in the present invention, but silicone varnishes that are solid at room temperature and have a molecular weight of 500 to 2,000 are particularly preferred. There are methyl silicone varnishes synthesized through a post-condensation polymerization reaction, phenyl silicone varnishes synthesized mainly from monophenyltrichlorosilane, and methylphenyl silicone varnishes synthesized mainly from monophenyltrichlorosilane and monomethyltrichlorosilane. In particular, phenyl silicone varnish was most suitable.

Various fluororesins are known for use in the present invention, including polytetrafluoroethylene, tetrafluoroethylene-hexafluoropropylene copolymer, polychlorofluoroethylene, polyvinyridine fluoride, and polyfluoroethylene. Vinyl compound, ethylene-tetrafluoro-ethylene copolymer, perfluoroalkoxy resin, etc. can be used.

Furthermore, the binder resin for the toner used in combination with a silicone resin may be one that has been conventionally used. Polymer, styrene-P-chlorostyrene copolymer, styrene-P-chlorostyrene copolymer, styrene-propylene copolymer, styrene-vinylnaphthalene copolymer, styrene-pinylnaphthalene copolymer, styrene-acrylic methyl acid 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- Q Methyl chlormethacrylate copolymer, styrene-acrylonitrile copolymer, styrene-vinyl methyl ether copolymer, styrene-vinyl ethyl ether copolymer, styrene-vinyl methyl ketone copolymer, styrene Styrenic copolymers such as -butadiene copolymer, styrene-isoprene copolymer, styrene-acrylonitrile-indene copolymer, polyvinyl chloride, polyvinyl acetate, polyethylene, polypropylene, polyester, polyurethane, Polyamide, epoxy resin, polyvinyl butyral, rosin, modified rosin, terbene resin, phenol resin, aliphatic or aliphatic hydrocarbon resin, aromatic petroleum resin, chlorinated paraffin, paraffin wax, etc. can be used alone or in combination. Furthermore, as the coloring substance used in the present invention, all known coloring substances can be used, but for example, carbon black, iron black, graphite, nigrosine, metal tsuba bodies of monoazo dyes (Hakama Kosho 4
No. 1-20153, No. 43-17956, No. 43-27596, No. 44-397, No. 4
5-26478), ultramarine blue, phthalocyanine flu, Hanzayello, benzine yellow, and various quinacridone lake pigments can be used. When carrying out the present invention, the above-mentioned fluororesin has a particle size of 5r.
Hereinafter, it is preferable to incorporate it into a binder resin containing a silicone resin as fine particles having a particle size of 2 or less particles, but polytetrafluoroethylene and polyvinylidene fluoride are particularly preferred as the fluororesin.

Furthermore, particularly good results were obtained when a binder resin containing a mixture of silicone resin and styrene resin was used. In carrying out the present invention, the manufacturing method of toner particles has no essential influence; the most commonly practiced method is used, i.e., silicone resin, other binder resin, colorant, and fluororesin. A method can be used in which the powder and, if necessary, other additives are premixed, the mixture is melt-kneaded, cooled, pulverized with paper, finely pulverized, and classified to a desired particle size.

When producing toner by this method, it should be noted that the fluororesin used in the present invention generally has a property that it is difficult to be dripped by many binder resins, so sufficient premixing and melt kneading are necessary. However, during pulverization, fine particles of fluororesin alone are generated. When a developer made by mixing a toner containing these fine particles of free fluororesin and a carrier is actually applied to a copying machine, although it may give a good image at the initial stage, it is not durable enough and cannot be copied repeatedly. If you do this, the image will become unclear. Although all of the causes are still not clear, the present inventors consider the following.

Fine particles of fluororesin tend to be negatively charged with respect to iron powder carriers.

Even in the case of negative toner, it is believed that these free particles, which are smaller than the particle size of the toner, tend to selectively form a film on the carrier rather than the toner when electrically attached to the carrier. As a result, the tribopotentials of the toner and carrier are changed, and the electrode effect of the carrier is reduced, resulting in a poor image density and a blurred image. In addition, when the toner is a positive toner, the free fluororesin fine particles that are negatively charged by the carrier are
It acts to reduce the charge on the toner and causes fogging. However, in the present invention, the silicone resin is contained in the binder resin of the toner, and both the silicone resin and the fluororesin have extremely small critical surface tension, so they cannot be mutually dispersed or dissolved. It is thought that the properties will be significantly improved.

Furthermore, since the organic component of the silicone resin helps in compatibility with the binder resin, the dispersibility and solubility of the fluororesin fine particles, the silicone resin, and the binder resin as a whole are extremely good, resulting in an excellent product free from the above-mentioned defects. This is considered to indicate a positive effect. The present inventors selected a developer that is resistant to mechanical damage by modeling the mechanical shock caused by the harsh operation that the developer encounters in the developing device during repeated copying. I found the scales very easy to do.

A specific embodiment of the method is as follows. Internal volume 2
Pour the developer into a ball mill pot of about 100 lbs. and rotate the pot at a speed of about 50 times per minute.

The triboelectric charge amount and V-D characteristics are measured over time to test the durability of the developer. If the amount of triboelectric charge and the V-D characteristics are stable, the developer tested can be considered to be an excellent developer with resistance to mechanical damage.
More specific embodiments will be described in Examples, but when the present inventors tested a large number of prototype developers using the above-mentioned method, they found that fine particles of fluororesin were found in the binder resin containing silicone resin. It was discovered that an extremely excellent developer can be obtained when a toner containing .

Furthermore, it was confirmed that the toner of the present invention has excellent durability even in continuous copying using a copying machine. The durability of the obtained toner is improved even if silicone resin or fluororesin is included in any of the binder resins mentioned above. ) was good. The amount of fluororesin to be added is as follows:
It is preferably 1 to 15 parts by weight, particularly preferably 2 to 1 part by weight, based on the weight of the binder resin 10 containing the silicone resin. The amount of silicone resin added is 1 to 3 parts by weight, preferably 2 to 15 parts by weight, based on 10 parts by weight of other binder resins.
It is best to use parts by weight. The toner of the present invention is flooded with a carrier to form a developer, and all known carriers can be used, such as iron powder, nickel powder, cobalt powder, glass beads, and the like. There are those treated with resin, fur brushes, etc.

The present invention will be explained in detail below with reference to Examples.

Example 1 10 parts by weight of styrene-butadiene copolymer (weight ratio styrene/butadiene = 85/15), 6 parts by weight of polytetrafluoroethylene (trade name, Lupron L-2, manufactured by Daikin Industries, Ltd.), carbon 9 parts by weight of black,
1 part by weight of silicone resin (trade name, KR-21 made by Haruji Kagaku) was mixed in a pole mill, then melted and kneaded in a roll mill, cooled, coarsely ground in a hammer mill, and finely ground in a supersonic jet mill. It was crushed to make toner.

15 parts by weight of this toner and carrier - iron powder (product name: EF
V250-400, manufactured by Nippon Tetsuko Co., Ltd.) and 85 parts by weight were mixed to prepare a developer. 1.5k9 of this developer was put into two ball mill pots, and the developing agent was added at a speed of 5 rotations per minute.

As shown in the attached table, almost no changes in triboelectric charge amount or image density were observed. Further, the triboelectric properties and flow properties hardly changed even under changing humidity conditions. In addition, a dry plain paper electrophotographic copying machine (product name, NP5000)
When continuous copying of 100,000 sheets was carried out using a Canon K (manufactured by Canon K, K), the initial good image was maintained and no deterioration in image quality was observed. That is, the image density at the initial stage of copying was 1:45 and remained at 1:37 even after copying 100,000 sheets.

In this example, a toner was produced in the same manner except that polytetrafluoroethylene was not included. This toner contains polytetrafluoroethylene (product name:
When 6% by weight of Luflon L-2 (manufactured by Daikin Industries, Ltd.) was added and further mixed with a carrier to form a developer and continuous copying was performed under the same conditions, the image density at the initial stage of copying was 1:45. However, after copying 20,000 sheets, it decreased to 0.82. Examples 2 to 9 The following formulations are as in Example 1.
I did the same thing.

As shown in the attached table, a model experiment using a ball mill pot revealed that it has excellent stability against mechanical damage. (All figures in the table are parts by weight.) However, in the table, Lublon L-2 and Luflon L-5 are the trade names of polytetrafluoroethylene made by Daikin Industries, and KF Polymer 1000 is the trade name of polyvinylidene fluoride made by Kureha Chemical. , FEP is tetrafluoroethylene-hexafluoropropylene copolymer, ETFE is ethylene-tetrafluoroethylene copolymer, KR-216 is the trade name of phenyl silicone varnish manufactured by Shin-Etsu Chemical, and KR-215 is methyl manufactured by Shin-Etsu Chemical. This is the trade name of phenyl silicone varnish.

In Examples 1 to 10, 2 parts by weight of Pomelo Fast Black B (alloy metal dye) was added for the purpose of charge control.

Further, in Example 11, 1 part by weight of nigrosine was added for the purpose of charge control. Triboelectric charge (AC/event) (measured by blow-off method) Image density Dry plain paper electrophotographic machine (
The image density of the portion where the latent image potential was +450 V was measured using a NP-5000 (trade name, manufactured by Canon K.K.).

Claims (1)

[Scope of Claims] 1. A toner for electrical latent images, characterized in that fine particles of a fluororesin are contained in a binder resin containing a silicone resin. 2 1 to 3 parts of silicone resin in 100 parts by weight of binder resin
The toner for electrical latent images according to claim 1, which contains 0 parts by weight. 3 Silicone resin has a molecular weight of 500 to 20
00 solid silicone varnish
The toner for electrical latent images according to item 1 or 2. 4. The toner for electrical latent images according to claim 1, which contains 1 to 15 parts by weight of fluororesin fine particles in 100 parts by weight of a binder resin containing a silicone resin. 5. The toner for electrical latent images according to claim 1 or 4, wherein the fluororesin fine particles have a particle size of 5 μm or less.