JPH0138302B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a toner for developing electrostatic latent images in electrophotography.

Conventionally, many methods are known for electrophotography, but in general, a certain charge is applied to a photosensitive plate using a photoconductive substance, and a light image of the image to be copied is irradiated onto the photosensitive plate. Forms an electrostatic latent image. This electrostatic latent image is generally developed with a developer to make it visible, and if necessary, transferred onto a transfer sheet such as paper, and then heated and fixed. Furthermore, an electrostatic recording method is also known in which an electrostatic latent image is formed by applying a charge directly onto an insulating layer and then developed.

As a developer for developing an electrostatic latent image, a mixture of colored powder called toner and carrier such as iron powder or glass beads is used.

Toner is generally a finely pulverized mixture of a binder resin and a colorant, but natural or synthetic resins are generally used as the binder resin, such as phenolic resin, modified rosin, coumaron resin,
Epoxy resins, polyester resins, polystyrene resins, styrene-butadiene copolymers, acrylic resins, polyacrylic acid ester resins, etc. are used singly or as a mixture of two or more types. Carbon black, organic pigments, dyes, triiron tetroxide (Fe ₃ O ₄ ), red iron oxide (Fe ₂ O ₃ ), etc. are often used as coloring agents.

These binder resins and colorants are hot-melted, kneaded, cooled, and coarsely pulverized using a hammer mill or the like, and then pulverized and classified into particle sizes of about 5 μm to 40 μm to produce toner for electrophotography.

Methods for fixing a toner image developed with such toner onto paper or the like include a heat chamber method and a heat roller method. The heat chamber method has problems with thermal efficiency, and as copying machines have become faster in recent years, its use has stopped. On the other hand, a heated roller method has come to be commonly used as a fixing method that can accommodate higher speeds.

Heat roller fixing is a method in which a transfer sheet such as paper supporting a toner image is passed between a pair of heated rollers, and the powder toner image is melted and fixed by heat and pressure. However, this method tends to cause so-called offset development, in which part of the toner image adheres to the roll surface when the toner image comes into contact with the roll. has been provided and has been effective. However, in this case, a device is required to always supply a fixed amount of mold release liquid, and the device is also complicated. Moreover, problems such as oil leakage and odor generation due to heating tend to occur. Therefore, recently, a method of performing heated roller fixing without using a releasing liquid has been studied. For example, a method by adding a releasing substance as in JP-A-49-42354, a method by cross-linking a binder resin as in JP-A-49-101031, or a method in JP-A-49-101031.
There are methods such as adding a rubbery substance, such as No. 50-68141.

However, after various studies by the inventor,
When a release material is added, so-called film development occurs in which a film of the release material is formed on the surface of the photosensitive plate, causing problems with fog and image quality. Also, crosslinking the binder resin will worsen the crushability.
In addition, dispersion of colorants, especially dyes that are poorly compatible with binder resins, tends to be a problem, which affects charging stability and tends to cause problems such as changes in image density or fog. Furthermore, when a rubbery substance is added, agglomeration tends to occur during storage, causing problems in fluidity. In this way, even if each of the conventional methods is adopted individually, the effect is small, so the reality is that a combination of two or more is put into practical use. You will face various problems. Therefore, there is a need for the development of an improved toner that does not impair other toner physical properties.

The object of the present invention is to provide a toner that improves the above-mentioned drawbacks.
That is, the object of the present invention is to provide an electrophotographic toner that can be efficiently and favorably fixed with a heated roller without causing offset development of the toner even when a fixing roller that does not supply a releasing liquid is used.

This object of the invention is achieved by a toner using a resin mixture containing a norbornene polymer as a binder resin.

In the present invention, examples of the resin to be mixed with the norbornene polymer as a binder resin include polyamide resins, polyurethane resins, epoxy resins, polyester resins, polyolefin resins, styrene resins, etc. In terms of compatibility, styrene resins are particularly preferred.

The styrene resin may be a styrene homopolymer or a copolymer of styrene and other vinyl monomers (styrene content usually 25% by weight or more). Monomers for forming copolymers with styrene include olefins, vinyl halides, vinyl esters, esters of unsaturated carboxylic acids,
anhydride), glycidyl compounds, vinyl ethers,
Examples include vinyl ketones, N-vinyl compounds, dienes, nitriles, and compounds containing two or more vinyl groups.

The norbornene polymer used in the present invention is prepared by a conventional method (for example,
It is a polymer obtained by ring-opening polymerization or copolymerization by the method described in No. 35800), and the monomers used include bicyclo (2.2.1) heptene-2; methyl-5-bicyclo (2.2.1). ) heptene-2, ethyl-5-bicyclo (2.2.1) alkyl-5-bicyclo (2.2.1) heptene-2 monomers such as heptene-2; methoxy-5-bicyclo (2.2.1) heptene- 2. Alkoxy-5-bicyclo (2.2.1) heptene-2 monomers such as ethoxy-5-bicyclo (2.2.1) heptene-2; cyano-
5-bicyclo(2.2.1) heptene-2; bicyclo(2.2.1) heptene-2-5-carboxylic acid ester monomer; bicyclo(2.2.1) heptene-2-5.6
Examples include diester monomers of dicarboxylic acids and mixtures thereof. A typical polymer is polynorbornene, which is a ring-opening polymer of bicyclo(2.2.1)heptene-2.

Such norbornene-based polymers differ from the temperature characteristics of melt viscosity and adhesive behavior during melting of general toner resins; for example, compared to styrene resins, the melt viscosity decreases less as the temperature increases, and the melt viscosity Less sticky. By mixing such a norbornene polymer into the binder resin, offset resistance in the toner fixing temperature range can be greatly improved. That is, at the time of fixing, the cohesive force of the toner itself becomes greater than the adhesive force of the toner to the roller, making it difficult for the toner to adhere to the roller.

The amount of norbornene polymer to be added is appropriately determined depending on its type and molecular weight as well as its offset properties and pulverizability as a toner, but usually the total concentration is required to prevent the offset phenomenon from occurring without losing the properties as a toner. Adhesive resin at least
An addition of 0.1% by weight, preferably 3% by weight is required. If the amount exceeds 50% by weight of the total binder resin, the temperature at which the offset phenomenon occurs becomes high and exceeds the temperature range considered for a fixing device, so the addition is not only meaningless, but also causes some deterioration in pulverizability.

The weight average molecular weight of the norbornene polymer is usually 1,000 to 5,000,000, preferably 500,000 to 2,000,000 in terms of offset resistance. Note that from the viewpoint of dispersibility, it is preferable that the amount of gel is small.

The toner of the present invention is preferably colored with a suitable colorant, ie, a pigment or dye. Toner colorants are known, such as carbon black, nigrosine dye, aniline blue, calco oil blue, chrome yellow, ultramarine blue, quinoline yellow, methylene blue chloride, monastral blue, malachite green oxalate, lamp black, rose bengal. , Monastralled, Sudanbrak BM, Spironbrak
There are TOH and mixtures thereof. The pigment or dye toner may be present in the toner in sufficient concentration to highly pigment the toner so as to form a clear visible image on the recording member.

The toner of the present invention may further contain other additives for improving kneading and dispersibility and crushability.

Examples of additives for improving kneading and dispersibility include higher fatty acids such as stearic acid, oleic acid, palmitic acid, linoleic acid, ricinoleic acid, or caprylic acid, zinc, manganese, iron,
Metal salts such as cobalt, nickel, copper, and magnesium, higher fatty acids having 28 or more carbon atoms,
Examples include natural or synthetic paraffins, fatty acid esters or partially saponified products thereof, alkylene bis fatty acid amides such as ethylene bis stearoyl amide, and low molecular weight polyalkylenes such as polyethylene and polypropylene. These compounds may be contained in the toner either alone or in an appropriate combination of two or more. The amount of these compounds added to the toner is generally 0 per 100 parts by weight of the resin component of the toner.
from 25 parts by weight, preferably from 2 to 10 parts by weight.

Similarly, o-phthalic acids or m
- Phthalate esters, such as triethylene glycol dibenzoate, pentaerythritol tetrabenzoate, sugar rose benzoate, benzoate esters such as glyceryl tribenzoate, tricyclohexyl citrate, such as p-toluenesulfonamide, N-cyclohexyl-p - Sulfonamides such as toluenesulfonamide, triphenyl phosphate, other chlorinated paraffins, chlorinated polyphenyl, polyethylene glycols, and mineral oils such as naphthenic oils, paraffinic oils, aromatic oils, and silicone oils. It can be added as a kneading and dispersion improver. The amount of these compounds added to the toner is generally determined by the resin component of the toner.
0 to 50 parts by weight, preferably 5 parts by weight per 100 parts by weight
40 parts by weight can be added.

Natural rosin or synthetic rosin can be used as an additive to improve grindability. The amount of these compounds added to the toner is generally from 0 to 30 parts by weight, preferably from 3 to 20 parts by weight, per 100 parts by weight of the resin component of the toner.

The toner for electrophotography of the present invention is an excellent toner that does not cause any offset phenomenon to the fixing roller, but also has good crushability and dispersibility, and the fixed image is clear and has little fog, and it can be used for a long time. Furthermore, it also exhibits effects such as no filming on the photosensitive plate.

Next, the present invention will be explained by examples. Note that all parts and percentages in the examples are based on weight.

Example 1 70 parts of polystyrene resin (Picolastick D-125, manufactured by Etsuo Corporation), 8 parts of carbon black (Regal 400R, manufactured by Cabot Corporation), 30 parts of polynorbornene (manufactured by CdF Chimie, Norsolex, molecular weight 2 million), Metal-containing dye (manufactured by Orient Chemical Co., Ltd.,
Two parts of Bontron S-31) were premixed in a ball mill for 24 hours, melted and kneaded in a roll mill at 120°C for 30 minutes, cooled, and then coarsely and finely crushed to obtain a toner having a particle size of about 5 to 25μ. , was used as a sample.

Similarly, a toner treated in the same manner as the above sample except that polynorbornene was not added and the polystyrene resin was used at 100 parts was used as a comparison sample.

10 parts of each of these toner images are mixed with 90 parts of iron powder carrier having an average particle size of about 50-80μ;
Two types of developers were created. Using these developers,
Next, an electrostatic latent image is formed by ordinary electrophotography, the toner image is transferred onto transfer paper, and a metal roller whose surface is coated with polyfluoroethylene and a silicone rubber roller are applied to the image surface of the transfer paper. Heat fixing roller consisting of 200~210℃
The toner image was fused and fixed by contacting it with pressure. Next, in order to investigate whether the fused toner image is transferred to the surface of the fixing roller and an offset phenomenon occurs, after each fixing operation, transfer paper without toner image was transferred to the fixing roller under the same conditions as above. The transfer paper was brought into pressure contact and stains caused by toner offset were observed on the transfer paper.

As a result, when the comparative sample toner was used, significant staining due to toner offset was observed on the transfer paper, but when the inventive sample toner was used, no staining occurred on the transfer paper and the toner It was confirmed that no offset phenomenon occurred. Further, when this fixing operation was repeated 5000 times, the same result was obtained.

Example 2 80 parts of a copolymer consisting of 70% styrene and 30% n-butyl acrylate, 20 parts of polynorbornene (CdF Chimie, Norsolex), carbon black (Cabot, Regal)
400R) 8 parts, metal-containing dye (manufactured by Orient Chemical Co., Ltd.,
Two parts of Bontron S-31) were premixed in a ball mill for 24 hours, and then melt-kneaded in a roll mill at 120°C for 20 minutes. Since this kneaded product did not stick to the roll, it was confirmed that the two polymers used had good compatibility. Next, a toner was prepared by processing in the same manner as in Example 1 and used as a sample. A toner was prepared as a comparative sample in exactly the same manner as described above, except that 100 parts of styrene-n-butyl acrylate copolymer was used without adding polynorbornene.

Using these two types of toners, the same operations as in Example 1 were performed except that a silicone rubber roller was used as the fixing roller and the fusing temperature was 190 to 200°C, and the offset properties of each toner were determined. Examined. As a result, it was found that a significant offset phenomenon occurred when the comparative sample toner was used, but it was found that no toner offset phenomenon occurred when the inventive sample toner was used. .

Example 3 Epoxy resin (manufactured by Ciel, Epicoat 1004)
70 parts of polynorbornene (manufactured by CdF Chimie, Nosolex), 8 parts of carbon black (Regal 400R, manufactured by Kabot Corporation), and 2 parts of metal-containing dye (manufactured by Orient Chemical Co., Ltd., Bontron S-31), A toner was prepared by processing in the same manner as in Example 1, and used as a sample. A toner was prepared in exactly the same manner as above except that 100 parts of epoxy resin was used without adding a polynorbornene polymer,
This was used as a comparison sample.

Using these two types of toners, the same operations as in Example 1 were performed to examine the offset properties of each toner. As a result, it was found that a significant toner offset phenomenon occurred when the comparative sample toner was used, but it was found that no toner offset phenomenon occurred when the inventive sample toner was used. It was done.

Example 4 80 parts of polyester resin (manufactured by Kao Atlas Co., Ltd., Atlask 382A), polynorbornene (CdF
(manufactured by Chimie, Nosolex, ) 20 copies, carbon black (manufactured by Cabot, Regal 400R) 8
1 part, and 2 parts of a metal-containing dye (Bontron S-31, manufactured by Orient Chemical Co., Ltd.) were mixed and treated in the same manner as in Example 1 to prepare a toner, which was used as a sample. A toner was prepared as a comparative sample in exactly the same manner as described above, except that 100 parts of the polyester resin was used and no polynorbornene polymer was added.

Using these two types of toners, the same operations as in Example 1 were performed except that a silicone rubber roller was used as the fixing roller and the fusing temperature was 190 to 200°C, and the offset properties of each toner were investigated. . As a result, it was found that a significant toner offset phenomenon occurred when the comparative sample toner was used, but it was found that no toner offset phenomenon occurred when the inventive sample toner was used. It was done.

Example 5 90 parts of a copolymer with a molecular weight of approximately 200,000 consisting of 80% styrene and 20% 2-ethylhexyl acrylate, 10 parts of polynorbornene (manufactured by CdF Chimie, Norsolex), 8 parts of carbon black (Regal 400R, manufactured by Kayabot) 1 part, 2 parts of metal-containing dye (manufactured by Orient Chemical Co., Ltd., Bontron S-31),
A toner was prepared by processing in the same manner as in Example 1, and used as a sample. The same procedure as above was performed except that 100 parts of styrene-2-ethylhexyl acrylate copolymer was used without adding polynorbornene.
A toner was prepared and used as a comparison sample.

Using these two types of toners, the same operations as in Example 1 were performed to examine the offset properties of each toner. As a result, it was found that a significant toner offset phenomenon occurred when the comparative sample toner was used, but it was found that no toner offset phenomenon occurred when the inventive sample toner was used. It was done.

Example 6 Molecular weight consisting of 95% styrene and 5% butadiene
300,000 copolymer 95 parts, polynorbornene (CdF
(Manufactured by Chimie, No Solex, ) 5 parts, Carbon black (Manufactured by Cabot, Regal 400R) 8
1 part and 2 parts of a metal-containing dye (Bontron S-31, manufactured by Orient Chemical Co., Ltd.) were mixed and treated in the same manner as in Example 1 to prepare a toner, which was used as a sample. A toner was prepared as a comparative sample in exactly the same manner as described above, except that 100 parts of the styrene-butadiene copolymer was used without adding a polynorbornene polymer.

Using these two types of toner, a silicone rubber roller is used as the fixing roller, and the fusing temperature is adjusted.
The temperature was set at 190 to 200 DEG C., and the other operations were the same as in Example 1, and the offset properties of each toner were examined. As a result, it was found that a significant toner offset phenomenon occurred when the comparative sample toner was used, but it was found that no toner offset phenomenon occurred when the inventive sample toner was used. It was done.

Claims (1)

[Claims] 1. An electrophotographic toner characterized in that a resin mixture containing a norbornene polymer is used as a binder resin.