JPS6355698B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to developer powder used in electrophotography, electrostatic recording, magnetic recording, and the like. Conventionally, as an electrophotographic method, U.S. Patent No. 2297691
Although a number of methods are known, such as those described in Japanese Patent Publication No. 42-23910, generally a photoconductive substance is used to form an electrical latent image on a photoreceptor by various means, and then The latent image is developed using developer powder (hereinafter referred to as toner), and after the toner image is transferred to a transfer material such as paper as necessary, it is fixed by heat, pressure, solvent vapor, etc. to obtain a copy. It is. Further, when a step of transferring a toner image is included, a step for removing residual toner is usually provided. Examples of methods for visualizing electrical latent images using toner include the magnetic brush method described in US Pat. No. 2,874,063, the cascade development method described in US Pat. No. 2,618,552, and the US Pat. The cloud cloud method described in U.S. Patent No.
A method using conductive magnetic toner described in Japanese Patent No. 3909258 is known. As toners applied to these developing methods, fine powders in which dyes and pigments are dispersed in natural or synthetic resins have conventionally been used. For example, particles obtained by dispersing a colorant in a binder resin such as polystyrene and separately pulverizing the particles into particles of about 1 to 30 μm are used as toner. As the magnetic toner, one containing magnetic particles such as magnetite is used. In the case of a system using a so-called two-component developer, the toner is usually mixed with carrier particles such as glass beads and iron powder. 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 and rheological properties due to environmental temperature changes. In addition, with many toners, the density of the resulting image decreases due to mutual deterioration of the toner, carrier particles, and photosensitive plate due to collisions between toner particles and carrier particles due to repeated development due to continuous use and contact between them and the photosensitive plate surface. 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 a so-called fog phenomenon. Among these undesirable phenomena, there are phenomena caused by the fragility of toner particles. If the toner is brittle, it will be easily crushed by mechanical force, which is preferable from the viewpoint of toner productivity. However, such toner is easily crushed into fine powder by the load applied to the toner in the developing device, contaminating the carrier particles and the developing sleeve, and the charge control of the toner particles themselves is poor. When the color becomes complete, undesirable phenomena such as fogging occur. As described above, the brittleness of toner is greatly related to the lifespan of the developer. In order to avoid such deterioration phenomena, it is possible to use polymers with high molecular weight, but when considering the thermal fixation of images that is usually performed in the final process of copying, the fixing temperature increases and more polymers are used during fixing. Since it requires a large amount of heat, it is not preferable in terms of energy conservation. Furthermore, it has been proposed to add a small amount of plasticizer to the toner in order to eliminate this phenomenon, but this has not always been successful as it has problems such as impairing the free flowing properties of the toner and contaminating the carrier etc. I haven't. On the other hand, if the toner is too hard, it becomes impossible to mechanically crush it, making it difficult to actually manufacture the toner. Conventionally, for the above-mentioned reasons, relatively low molecular weight (several thousand) polystyrene or styrene-butyl methacrylate copolymer having appropriate hardness has been used as a binder resin for toner. However, recently there has been an extremely strong demand for improving the reliability of copying machines. Additionally, copying machine manufacturers are currently striving to develop and produce copying machines with longer lifespans from the viewpoint of maintenance-free use. Under these circumstances, when we reviewed the various properties of toners, we found that the relatively low molecular weight polystyrene or styrene-butyl methacrylate copolymer used as binder resins for toners was not sufficiently hard. It was found that a material with even higher hardness was needed. In recent years, the most common fixing method in copying machines has been the heated roller fixing method, but the heated roller fixing devices of currently commercialized copying machines do not apply oil to the rollers. The ones who are there account for the majority. However, oil application causes undesirable problems such as the oil vaporizing and causing discomfort to the user, oil stains on the seat, complicating the fixing device, making troubles more likely to occur, and increasing costs. . Therefore, there is a desire for a hot roller fixing device that does not apply oil or that applies only a small amount of oil, but this will not be possible without improvements in toner. The difficulty in using a hot roller fuser that does not apply oil is that since no oil is applied, the toner must maintain releasability to compensate for this, so it is necessary to maintain a low fusing point and maintain durability. The problem is that it is difficult to obtain a toner with good offset and sticking resistance, and it is even more difficult to obtain a toner that is excellent in both fixing properties and development properties. Conventional toners have either binder resins that have a molecular weight distribution curve with one peak, multiple peaks in the low molecular weight region, or are composed of completely different compounds with different molecular weight distributions. It was a mixture. The above toners could hardly be called excellent toners in terms of both fixing properties and developing properties. Conventionally, various methods have been proposed for improving the fixing characteristics of toner for hot roll fixing. U.S. Pat. No. 3,941,898 proposes a toner using a crosslinked polymer as a binder resin, and if that method is followed, offset resistance and sticking resistance can be significantly improved. However, the fixing temperature is low and offset resistance is poor.
Good sticking resistance and sufficient fixing properties cannot be obtained. Also, crosslinked polymers have drawbacks such as difficulty in dispersing pigments and incompatibility with other polymers, so toners using crosslinked polymers as a binder resin have difficulties in obtaining good development characteristics. be. Also
DOLS2352604 proposes a toner in which a styrene resin is mixed with low molecular weight polypropylene, but in order to obtain a sufficient effect on offset resistance, it is necessary to contain a large amount of low molecular weight polypropylene. This has the disadvantage that the toner cohesiveness increases, resulting in poor development characteristics. An object of the present invention is to provide a developing powder for developing a negative latent image. Another object is to provide developer powder that does not offset the heated roller. Furthermore, the object of the present invention is to reduce the amount of adhesion to the carrier, toner holding member, photoreceptor surface, cleaning blade, etc., and less damage to them, as well as to have excellent impact resistance, to prevent agglomeration, and to prevent fluidization. The object of the present invention is to provide a developing powder having excellent properties and durability, a high blocking temperature, and a low fixing temperature. Its characteristics are as follows:
A binding substance containing a polymer having a vinyl monomer as a constituent component shown in any of The chromatogram (GPC chromatogram) measured by gel permeation chromatography of the vinyl polymer in the binding substance has a molecular weight of 2×10 ³ to 8.
The developing powder contains a binding substance having at least one maximum value in each region of ×10 ⁴ and molecular weight of 10 ⁵ to 2 × 10 ⁶ .

【formula】

【formula】

【formula】

[Formula] However, R ₁ : hydrogen, lower alkyl group, R ₂ : lower alkylene group, R ₃ , R ₄ : hydrogen, lower alkyl group,
Allyl group, R ₅ : Hydrogen, lower alkyl group GPC chromatography in the molecular weight range of 10 ⁵ to 2×10 ⁶ effectively contributes to preventing offset to the hot roll and improving development characteristics. It is a vinyl polymer with a maximum value of gram. However, as the amount of polymers having a molecular weight in this range increases, an undesirable phenomenon occurs in that the fixing temperature becomes high for thermal fixing. Therefore, in the GPC chromatogram, the maximum value is 2×
Polymers in the range of 10 ³ to 8×10 ⁴ must be properly mixed. The polymer applicable to the present invention is
In the GPC chromatogram, the molecular weight is 2×10 ³ ~
The molecular weight may be adjusted at the stage of synthesis so that it has at least one maximum value in the range of 8×10 ⁴ and 10 ⁵ to 2×10 ⁶ , or the molecular weight is 2×10 ³
Polymer P has a maximum value of ~8× ¹⁰⁴ and the molecular weight is
It may be created by mixing with a polymer Q having a maximum value of 10 ⁵ to 2×10 ⁶ . In the latter case, the mixing weight ratio of polymers P and Q is preferably Q/P=2/1 to 1/50. In the region of Q/P>2, if a currently commonly used thermal fixing method is employed, a large amount of thermal energy is required, which is not preferable. Q/P<
In the 1/50 region, no effect of mixing P and Q is observed. Further, P and Q do not necessarily have to have the same composition, but it is preferable that the main components of the monomers are the same. In the present invention, in order to measure the molecular weight at the peak position of the molecular weight distribution of the vinyl polymer, an appropriate method for normal gel permeation chromatography may be used as described below. 1 Measurement conditions Temperature 25°C Solvent Tetrahydrofuran Flow rate 1 ml 1 min Sample concentration 8 mg 1 ml Tetrahydrofuran solution Sample injection volume 0.5 ml 2 Column In order to appropriately measure the molecular weight range of 10 ³ to 2 × 10 ⁶ , the column used is a commercially available polystyrene gel. A combination of multiple columns is used, and in the present invention, a combination of μ-Styragel 500, ^{10 3} , 10 ⁴ , 10 ⁵ manufactured by Waters, Shodex A-802, 803, 804, 805 manufactured by Showa Denko K.K.
A combination of these is appropriate. 3 Calibration curve The calibration curve was created using standard polystyrene, such as those manufactured by Pressure Chemical Co. or Toyo Soda Kogyo Co., Ltd. with a molecular weight of 6×10 ² , 2.1×10 ³ ,
4×10 ³ , 1.75×10 ⁴ , 5.1×10 ⁴ , 1.1×10 ⁵ , 3.9
It is appropriate to use standard ^{polystyrene of} at least ^{10 points} . 4 Detector An RI (refractive index) detector is used as the detector. A polymer containing at least 1% by weight of any of the vinyl monomers represented by the structural formulas - above as a constituent component may also contain other vinyl monomers as a constituent component. Other vinyl monomers include styrene and styrene substitutes such as α-methylstyrene and P-chlorostyrene; acrylic acid, methyl acrylate, ethyl acrylate, butyl acrylate, dodecyl acrylate, octyl acrylate,
Monocarboxylic acids having double bonds such as phenyl acrylate, methacrylic acid, methyl methacrylate, ethyl methacrylate, butyl methacrylate, octyl methacrylate, acrylonitrile, methacrylonitrile, etc.; for example, maleic acid, Dicarboxylic acids with double bonds and substituted products thereof such as butyl maleate, methyl maleate, dimethyl maleate, etc.; vinyl esters such as vinyl chloride, vinyl acetate, vinyl benzoate, etc.; vinyl methyl ketone, Vinyl monomers such as vinyl ketones such as vinyl exyl ketone; vinyl ethers such as vinyl methyl ether, vinyl ethyl ether, vinyl isobutyl ether, etc. may be used alone or in combination of two or more. The vinyl polymer having the above structure is preferably a styrene copolymer, and the vinyl polymer contains 50 to 90% by weight, preferably 60 to 85% by weight of the styrene monomer component, which is styrene and its substituted product. It is better to contain %. The above-mentioned vinyl polymers are synthesized by known methods, such as suspension polymerization, emulsion polymerization, solution polymerization, and bulk polymerization. In addition, in order to adjust the molecular weight, known molecular weight regulators such as mercaptans such as lauryl mercaptan, phenyl mercaptan, butyl mercaptan, and dodecyl mercaptan, and halogenated carbons such as carbon tetrachloride and carbon tetrabromide are used. can do. The vinyl polymer containing any of the vinyl monomers represented by the above structural formula ~ is present in the binding material in an amount of 1 to 100% by weight (more preferably 2 to 100% by weight).
Particularly preferably 3 to 100% by weight). Particularly preferably, 50 to 100% by weight (more preferably 70 to 70% to
100% by weight, particularly preferably 90 to 100% by weight). The vinyl polymer, which does not contain any of the vinyl monomers having the structural formula ~, is contained in the binding material in an amount of 0 to 99% by weight (more preferably 0 to 98% by weight, particularly preferably 0 to 97% by weight). It's okay. The binding substance contains a binding substance other than vinyl polymer in an amount of 0 to 50% by weight (more preferably 0 to 30% by weight,
Particularly preferably 0 to 10% by weight). For example, silicone resin, polyester, polyurethane, polyamide, epoxy resin, polyvinyl butyral, rosin, modified rosin, terpene resin, phenolic resin, aliphatic or alicyclic hydrocarbon resin, aromatic petroleum resin, chlorinated paraffin, paraffin wax etc. The magnetic fine particles to be contained in the developing powder to obtain magnetic toner may be any material that exhibits magnetism or can be magnetized, such as iron, manganese, nickel, etc.
These include metals such as cobalt and chromium, magnetite, hematite, various ferrites, manganese alloys, and other ferromagnetic alloys.
A fine powder of 0.05 to 5μ (more preferably 0.1 to 2μ) can be used. The amount of magnetic fine particles contained in the developer powder is preferably 15 to 70% by weight (more preferably 25 to 45% by weight) of the total weight of the developer powder. Further, various substances can be added to the toner used in the present invention for the purpose of coloring, controlling charge, etc. Examples include carbon black, iron black, graphite, nigrosine, metal complexes of monoazo dyes, ultramarine blue, phthalocyanine blue, Hansa yellow, benzidine yellow, quinacridone, and various lake pigments. Alternatively, examples include polytetrafluoroethylene, polyethylene, polypropylene, fatty acids or their metal salts, lubricating compounds such as bisamide, and plasticizers such as dicyclohexyl phthalate. In particular, lubricating compounds are effective against wear and scratches on the photoreceptor surface, cleaning member, developing sleeve surface, carrier particles, and the like. Alternatively, colloidal silica or the like may be included in the developer powder as a fluidity improver. Furthermore, the developing powder of the present invention may optionally contain iron powder,
It is used as a developer for electrical latent images when mixed with carrier particles such as glass beads, nickel powder, and ferrite powder. It can also be used in combination with colloidal silica fine powder for the purpose of improving the free-flowing properties of the powder, and abrasive fine particles such as cerium oxide for preventing toner adhesion. Next, an electrophotographic method using the developing powder according to the present invention will be explained. The step of developing the electrical latent image using toner includes the aforementioned magnetic brush method, cascade development method, powder cloud method, method using conductive magnetic toner described in U.S. Pat. No. 3,909,258, Alternatively, there is a method using high-resistance magnetic toner.
The developing powder according to the present invention is also suitable for a developing method using a so-called one-component developer containing magnetic fine particles. In the process of transferring the developed image used in the present invention to a transfer target member, a corona transfer method, a bias transfer method, an electrostatic transfer method such as a method using a conductive roller, a method of transferring using a magnetic field, etc. are used. . Further, in the present invention, a blade cleaning method, a fur brush cleaning method, a magnetic brush cleaning method, etc. are applied to the step of removing residual toner on the photosensitive layer or the insulating layer. Although various methods can be used for fixing, a hot roll fixing method is most preferred. In the hot roll fixing method, the developer powder image on the support is passed between a pair of rollers. At least one of the rollers is heated to fuse the developing powder to the support. The developer powder of the present invention does not offset the rollers or cause paper wrapping. The surface of this roller is preferably covered with a fluororesin or silicone rubber, particularly preferably with a fluororesin. Furthermore, a release liquid such as silicone oil may be used in the heated roller. Example 1 70 parts by weight of styrene-butyl acrylate copolymer (monomer weight ratio 65:35) with a number average molecular weight of 9000,
By mixing 10 parts by weight of a styrene-diethylaminoethyl methacrylate copolymer (90:10) with a number average molecular weight of 5.100 and 20 parts by weight of a styrene-butyl acrylate copolymer (65:35) with a number average molecular weight of 205,000, a vinyl-based A polymer mixture was obtained. In a ball mill, 100 parts by weight of a polymer mixture having maximum values of 10,400 and 220,000 in the molecular weight distribution curve determined by GPC, 60 parts by weight of magnetic powder (triiron tetroxide with an average particle size of 0.3μ), and 2 parts by weight of low molecular weight polypropylene. The mixture was pulverized and mixed, and then melted and kneaded using a roll mill. After cooling, it was coarsely pulverized using a hammer mill, and then finely pulverized using a supersonic jet pulverizer. The obtained powder was classified using an air classifier, and particles of approximately 5 to 35 μm were collected and used as developer powder. 1 part by weight of colloidal silica powder produced by a wet method was added to 100 parts by weight of this developing powder and mixed to prepare a developer. This developing powder did not block even at 50°C and had excellent fluidity. Next, 100 parts by weight of zinc oxide, 20 parts by weight of styrene-butadiene copolymer, and n-butyl methacrylate.
A mixture of 40 parts by weight, 120 parts by weight of toluene, and 4 parts by weight of 1% rose bengal methanol solution was dispersed and mixed in a ball mill for 6 hours. This is 0.05mm
The coating was applied to a thick aluminum plate using a wire bar to a dry coating thickness of 40 μm, and the solvent was evaporated with warm air to produce a zinc oxide-binder photoreceptor in the form of a drum. This photoreceptor was subjected to -6 KV corona discharge to uniformly charge the entire surface, and then an original image was irradiated to form an electrostatic latent image. This latent image was developed using the developer described above using the developing device shown in FIG. In the figure, reference numeral 1 denotes the photosensitive drum, which rotates at a constant speed in the direction of the arrow. 3 is a 50 mm diameter cylindrical sleeve for carrying and conveying the developer 6. The sleeve surface magnetic flux density is 700 gauss, and the sleeve rotating magnet fixed (sleeve circumferential speed is the same as that of the drum, rotation direction is opposite) type developer with a distance between the ear cutting blade 4 and the sleeve 3 surface of 0.2 mm is installed between the photosensitive drum surface and the sleeve surface. The distance was set to 0.25 mm, and a 1 KHz 1.3 KV AC and -150 V DC bias was applied to the sleeve. After development using the developer in the above-mentioned developing device, the powder image was transferred while irradiating -7 KV direct current corona from the back side of the transfer paper to obtain a copied image. The remaining developer on the photosensitive drum was removed using a magnetic brush cleaner, and the fixing was done using a commercially available plain paper copier (product name:
This was done using a hot roll using a NP-200J (manufactured by Canon). A clear image without fogging was obtained. Furthermore, there was no offset to the fixing roller, and the fixing performance was excellent. Even after a durability test of 20,000 sheets, clear images with high image density were obtained. Furthermore, no scratches or toner adhesion were observed on the developing sleeve. Comparative Example 1 Styrene with a number average molecular weight of 9000 as a binder resin
The same procedure as in Example 1 was carried out except that 90 parts by weight of butyl acrylate copolymer and 10 parts by weight of styrene-diethylaminoethyl methacrylate copolymer having a number average molecular weight of 5100 were used, but clear images were not obtained. However, offset to the fixing roller was observed. Furthermore, when a durability test of 20,000 sheets was conducted, the image density decreased. Example 2 50 parts by weight of styrene-butyl acrylate copolymer (monomer weight ratio 65:35) with a number average molecular weight of 5400,
10 parts by weight of a styrene-diethylaminoethyl methacrylate copolymer (90:10) with a number average molecular weight of 5,100 and 40 parts by weight of a styrene-butyl acrylate copolymer (65:35) with a number average molecular weight of 156,000 are mixed to form a vinyl-based material. A polymer mixture was obtained. Except for using 100 parts by weight of a polymer having maximum values at 7100 and 178000 in this GPC chromatogram, 70 parts by weight of magnetic powder (triiron tetroxide with an average particle size of 0.5μ), and 2 parts by weight of low molecular weight polyethylene. When the same procedure as in Example 1 was carried out, clear images without fog were obtained. Furthermore, there was no offset to the fixing roller, and the fixing performance was excellent. Even after carrying out a durability test of 20,000 sheets, clear images with high image density were obtained, and no toner fusion was observed on the developing sleeve. Example 3 42 parts by weight of styrene-butyl methacrylate copolymer (monomer weight ratio 70:30) with a number average molecular weight of 4300, 8 parts by weight of styrene-4-vinylpyridine copolymer (95:5) with a number average molecular weight of 7800 and 50 parts by weight of a styrene-butyl acrylate copolymer (65:35) having a number average molecular weight of 156,000 to obtain a vinyl polymer mixture. In this GPC chromatogram, the maximum values at 6500 and 180000 are 100 parts by weight of polymer, 60 parts by weight of magnetic powder (ferrite powder with an average particle size of 0.5μ),
The same procedure as in Example 1 was conducted except that 5 parts by weight of carbon black and 2 parts by weight of low molecular weight polypropylene were used, and good results were obtained. Example 4 40 parts by weight of styrene-butyl acrylate copolymer having a number average molecular weight of 5400 (monomer weight ratio 65:35),
A vinyl polymer mixture was obtained by mixing 10 parts by weight of polydiethylaminoethylmethacrylamide and 50 parts by weight of a styrene-butyl acrylate copolymer (65:35) having a number average molecular weight of 156,000. In this GPC chromatogram, 100 parts by weight of polymer having maximum values at 7300 and 178000, 9 parts by weight of carbon black,
A toner was prepared from 2 parts by weight of low molecular weight polypropylene. 12 parts by weight of this toner and 88 parts by weight of carrier iron powder (trade name: EFU250/400) were mixed to prepare a developer. This developer was subjected to reversal development using a commercially available copying machine (trade name: NP-5000, manufactured by Canon). A clear image was obtained. Good images were obtained even after 20,000 copies were made. Example 5 In Example 1, a styrene-2-vinylpyridine copolymer having a number average molecular weight of 7100 (monomer weight ratio 90:10) was used instead of the styrene-diethylaminoethyl methacrylate copolymer.
Other than obtaining a polymer mixture with maxima at 10500 and 220000 in the GPC chromatogram,
When the same procedure was carried out, good results were obtained.

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional view of an embodiment of a developing device that uses a magnetic developer. 1...Photosensitive drum. 3...Cylindrical sleeve. 4...
…blade. 6...Developer.

Claims (1)

[Scope of Claims] 1 A binding material comprising a polymer having a vinyl monomer represented by any of the following structural formulas as a constituent, wherein styrene in the vinyl polymer in the binding resin The content of the system monomer component is 50 to 90% by weight, and the chromatogram measured by gel permeation chromatography of the vinyl polymer in the binding substance has a molecular weight of 2 × 10 ³ to
A developing powder characterized by containing a binding substance having at least one maximum value in each region of 8×10 ⁴ and a molecular weight of 10 ⁵ to 2×10 ⁶ . [Formula] [Formula] [Formula] [Formula] [However, R ₁ : Hydrogen, lower alkyl group, R ₂ : Lower alkylene group, R ₃ , R ₄ : Hydrogen, lower alkyl group,
Allyl group, R ₅ : hydrogen, lower alkyl group]