JPH0414344B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a carrier for negatively chargeable toner. Generally, in electrophotography, electrostatic recording, etc., toner, which is a colored fine powder, and carrier are used to develop an electrostatic image formed on an image support made of a photoconductive photoreceptor or dielectric material. The following developer is used. The toner that makes up this developer is
During the conveyance process, the toner rubs against the carrier and a charge of the opposite polarity to that of the electrostatic charge image is induced in the toner, and during the development process by the developer, the toner electrostatically adheres to the image support and forms a visible image. is formed. Therefore, the toner in the developer in the developing device is consumed each time development is performed, but the developing device is replenished with new toner accordingly, so that the toner in the developing device is constantly renewed. However, the carrier, which is initially prepared, is used repeatedly over a long period of time, and as a result, the characteristics of the carrier deteriorate as development is repeated. For example, a portion of the toner may become fused to the carrier surface, resulting in so-called spent toner, which may reduce the triboelectric charging properties of the carrier, or may reduce the desired effect in image quality adjustment performed by applying a bias voltage to the developer. is not obtained, and good development cannot be achieved. Further, inorganic powder or granules are generally used as they are as carriers, but if the surface condition of the carriers is centric, the moisture resistance of the developer decreases and similarly good development cannot be achieved. As a means to solve the above-mentioned problems, for example, it is possible to use inorganic particles as a carrier core material, and to form a coating layer on the surface of the carrier core material, which is made of a resin that has excellent frictional charging characteristics with the toner.
This is disclosed in JP-A No. 27879, Japanese Patent Application Laid-Open No. 13954-1984, and the like. According to the so-called coating carrier having such a resin coating layer, deterioration of the characteristics of the developer due to spent toner adhering to the carrier surface can be suppressed to some extent. However, developers using conventional resin-coated carriers have the disadvantage that during the process of flowing in the developing device, they collide with the container wall, causing the resin coating layer to be missing from the carrier surface, resulting in deterioration of the carrier's performance. . Therefore, as described in JP-A-55-33109, for example, a layer of a silane coupling agent such as alkyltrialkoxysilane and tetraalkoxysilane is provided on the surface of the magnetic material in advance, and a resin coating layer is further provided on the surface of the magnetic material. There are also attempts. However, with this method, the silane coupling agent is highly hydrolyzable, resulting in reduced moisture resistance and durability, and the low reactivity of the silane coupling agent to magnetic materials reduces the coating strength of the coating layer. Furthermore, there is a drawback that it is difficult to control the charge polarity. As described above, the reality is that no carrier that is fully satisfactory for practical use has been found at present. The present invention has been made based on the above-mentioned circumstances, and an object of the present invention is to have a resin coating layer, which does not cause toner adhesion and has little deterioration of characteristics, and in which the resin coating layer is a carrier layer. It is an object of the present invention to provide a negatively chargeable toner carrier that is firmly bonded to a core material, exhibits little deterioration in characteristics even after long-term use, and is capable of achieving good development. Another object of the present invention is to provide a negatively chargeable toner carrier having excellent moisture resistance. The above object is to form a coating layer of a compound represented by the following general formula or a salt thereof and a resin on the surface of the carrier core material, and to form a coating layer of the compound or salt thereof in the coating layer. This can be achieved by using a negatively chargeable toner carrier having a proportion of 0.5 to 5% by weight. general formula Here, R: an alkyl group, alkenyl group, or aralkyl group having 9 to 18 carbon atoms q: 0 or a positive integer X: -CH ₂ CH ₂ -,

【formula】 or

[Formula] is. In order to produce the carrier for negatively chargeable toner of the present invention, (1) the carrier core material is treated with a compound represented by the above general formula (hereinafter referred to as "compound") or its salt, and then a resin coating is applied. Method (2) A method of coating a carrier core material with a resin containing a compound or a salt thereof.(3) A method of coating a carrier core material with a monomer containing a compound or a salt thereof and polymerizing the monomer. can be used. To explain in detail, in the case of method (1), a carrier core material is treated with a compound or a salt to obtain a treated core material, and a solution in which a coating resin is dissolved in a solvent is applied to the treated core material using, for example, a fluidizing bed device. It may be applied to the core material and allowed to dry, or a monomer providing a coating resin may be similarly applied and polymerized. Also in the case of methods (2) and (3), known means can be used as the coating means. According to method (1), as schematically shown in FIG. 1, the coating layer 2 formed on the outer surface of the carrier core material 1 is a layer 2A of the compound or its salt.
and a resin layer 2B,
Particularly excellent moisture resistance and durability can be obtained. Also method (2)
Alternatively, according to method (3), as shown in FIG. 2, the coating layer 2 is made of a resin containing the compound or its salt, which has the advantage of being particularly easy to manufacture. In the present invention, the particle size of the carrier core material is
A conventional carrier core of 30 to 1000 microns, preferably 30 to 200 microns, such as sand, glass, or metals such as cobalt, iron, copper, nickel, ferrite, zinc, aluminum, brass, or their alloys or oxides thereof. Although materials used as materials can be used, in reality, they are appropriately selected according to the developing method employed. This carrier core material is preferably spherical. Specific examples of the compound or salt thereof used in the present invention include, for example, the following. Exemplary compound Product: "Nitsukor TOP-O" (manufactured by Nikko Chemicals) Product: "Nitsukor SLP-N" (manufactured by Nikko Chemicals) Product: “Nitsukor DOP-8N” (manufactured by Nikko Chemicals) Product: "Nitsukor TLP-4" (manufactured by Nikko Chemicals) In the present invention, various coating resins can be used, including styrenes such as styrene, parachlorostyrene, and α-methylstyrene; methyl acrylate, ethyl acrylate, n-propyl acrylate, and acrylic α-Methylene aliphatic monocarboxylic acid esters such as 2-ethylhexyl acid, phenyl acrylate, methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, 2-ethylhexyl methacrylate, phenyl methacrylate; acrylonitriles, methacrylonitrile Vinyl nitriles such as vinyl methyl ether and vinyl isobutyl ether; Vinyl pyridines such as 2-vinylpyridine and 4-vinylpyridine; N-vinyl cyclic compounds such as N-vinylpyrrolidone; Vinyl methyl ketone and vinyl Vinyl ketones such as ethyl ketone and methyl isopropenyl ketone; propylene,
Unsaturated hydrocarbons such as ethylene, isoprene, butadiene; Polymers made of monomers such as halogenated unsaturated hydrocarbons such as chloroprene, copolymers of two or more of these monomers, and mixtures thereof. Alternatively, non-vinyl condensation resins such as rosin-modified phenol-formalin resins, oil-modified epoxy resins, polyester resins, polyurethane resins, and polyimide resins, or mixtures of these and the vinyl resins can be used. The amount of coating of the compound or its salt and the coating resin must be within an appropriate range,
If the coating amount of the compound or its salt is too large, the compound or its salt will precipitate and the adhesion of the coating layer to the carrier core material will be reduced, and the fluidity of the developer will decrease and transport Sexuality becomes worse. The amount of coating is within the range of 0.5 to 5% by weight of the compound or its salt based on the carrier core material. In addition, in the negatively chargeable toner carrier of the present invention, two or more of the above compounds or salts thereof may be used in combination. Furthermore, the glass transition temperature of the coating resin is at least
The temperature is preferably 60°C. If the glass transition temperature is low, the resin will become sticky when heat is generated due to friction between the carriers or between the carrier and the wall of the developing device, resulting in poor fluidity. Become. In addition, the carrier of the present invention has the following characteristics for the toner used together with the carrier:
It is preferable that it provides a charge of 5 to 40 microcoulombs/g in absolute value under normal usage conditions. The toner constituting the developer together with the carrier of the present invention is a negatively charged toner made by dispersing a colorant in a resin, and various thermoplastic resins are used as the binder resin. Specific examples include styrene, parachlorostyrene, α
- Styrenes such as methyl styrene; methyl acrylate, ethyl acrylate, n-propyl acrylate, lauryl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, lauryl methacrylate, α-methylene aliphatic monocarboxylic acid esters such as 2-ethylhexyl methacrylate; vinyl nitriles such as acrylonitrile and methacrylonitrile; 2-vinylpyridine, 4
- Vinylpyridines such as vinylpyridine; Vinyl ethers such as vinyl methyl ether and vinyl isobutyl ether; Vinyl ketones such as vinyl methyl ketone, vinyl ethyl ketone, and methyl isopropenyl ketone; ethylene, propylene,
Polymers of monomers such as unsaturated hydrocarbons such as isoprene and butadiene and their halogen compounds, and halogenated unsaturated hydrocarbons such as chloroprene, or copolymers obtained by combining two or more of these monomers. , and mixtures thereof, or non-vinyl condensation resins such as rosin-modified phenol-formalin resins, oil-modified epoxy resins, polyester resins, polyurethane resins, polyimide resins, cellulose resins, and polyether resins, or these and the above-mentioned vinyl resins. Mention may be made of mixtures of. Further, as specific examples of the coloring agent, for example,
Mention may be made of carbon black, nigrosine dye, aniline blue, calco oil blue, chrome yellow, ultramarine blue, methylene blue, rose bengal, phthalocyanine blue, or mixtures thereof. Since the carrier for negatively chargeable toner of the present invention is as described above, the carrier core material is covered with the coating layer 2 made of the compound or its salt and resin, so it will be understood from the examples described later. As shown in the figure, the coating layer firmly adheres to the carrier core material and does not come off, nor does toner adhesion, resulting in great durability and maintaining its excellent properties over a long period of time. As a result, overall good electrostatic image development can be achieved. Of course, various additives can be added to the carrier of the present invention as required. EXAMPLES The present invention will be explained below with reference to Examples, but the present invention is not limited thereto. Example 1 Iron powder with an average particle size of 100 microns was used as the carrier core material, and 1 kg of it was coated with "Nitsukor TOP-O".
(manufactured by Nikko Chemicals Co., Ltd.) A solution of 10 g of Exemplified Compound (1) dissolved in 400 ml of toluene was added and stirred for 3 hours, after which the solid matter was filtered off and dried to obtain a treated core material.
This treated core material is used in a scanning electron microscope "JSH-T200"
(manufactured by JEOL Ltd.) when observed at 3500x magnification.
It was found that a uniform and good film was formed. To this treated core material, 70 g of methyl methacrylate and 30 g of styrene were mixed, and a solution containing 2.5 g of lauroyl peroxide as a polymerization initiator was added, stirred for about 30 minutes, and left to stand to separate the supernatant liquid. Then, 500 ml of an aqueous solution containing 1.5 g of colloidal calcium phosphate as a dispersion stabilizer was added, and polymerization was carried out at a temperature of 75° C. for 8 hours while thoroughly dispersing the mixture.
Thereafter, the system was cooled, 2 ml of concentrated hydrochloric acid was added, and after stirring for 10 minutes, the solid matter was taken out and thoroughly washed with water to obtain a carrier of the present invention. Example 2 1 kg of the same treated core material as in Example 1 was mixed with methyl methacrylate:styrene = 70:30 by weight
Methyl methacrylate-styrene copolymer 15g
The carrier of the present invention was obtained by treating with a solution prepared by dissolving the above in 500 ml of toluene using a fluidizing bed apparatus. This will be referred to as "Sample 2." Example 3 Using a solution in which 5 g of "Nitsukor TOP-O" (manufactured by Nikko Chemicals) and 15 g of methyl methacrylate-styrene copolymer with a weight ratio of methyl methacrylate: styrene = 70:30 were dissolved in 500 ml of toluene, the average particle size was determined. A carrier of the present invention was obtained by processing 1 kg of iron powder with a diameter of 100 microns using a fluidizing bed device. This will be referred to as "Sample 3." Example 4 A treated core material was obtained by treating 1 kg of iron powder with an average particle size of 100 microns using a solution of 5 g of "Nitsukor TOP-O" (manufactured by Nikko Chemicals) dissolved in 300 ml of toluene using a fluidization bed device. . This treated core material was treated with a solution in which 15 g of methyl methacrylate-styrene copolymer having a weight ratio of methyl methacrylate:styrene=70:30 was dissolved in 500 ml of toluene to obtain a carrier of the present invention. This will be referred to as "Sample 4." Example 5 Example 1 except that “Nitsukol SLP-N” (manufactured by Nikko Chemicals) (exemplified compound (2)) was used instead of “Nitsukol TOP-O” in Example 1.
A carrier of the present invention was obtained in the same manner as described above. This will be referred to as "Sample 5." Example 6 A carrier of the present invention was obtained in the same manner as in Example 2 except that "Nitsukol SLP-N" was used instead of "Nitsukol TOP-O" in Example 2. This will be referred to as "Sample 6". Example 7 A carrier of the present invention was obtained in the same manner as in Example 3 except that "Nitsukol SLP-N" was used instead of "Nitsukol TOP-O" in Example 3. This will be referred to as "Sample 7." Example 8 A carrier of the present invention was obtained in the same manner as in Example 4 except that "Nitsukol SLP-N" was used instead of "Nitsukol TOP-O" in Example 4. This will be referred to as "Sample 8." Example 9 The carrier of the present invention was prepared in the same manner as in Example 1 except that “Nitsukol DOP-8N” (manufactured by Nikko Chemicals) (exemplary compound (3)) was used instead of “Nitsukol TOP-O” in Example 1. I got it. This will be referred to as "Sample 9." Example 10 A carrier of the present invention was obtained in the same manner as in Example 2 except that "Nitsukor DOP-8N" was used instead of "Nitsukol TOP-O" in Example 2. This will be referred to as "Sample 10." Example 11 A carrier of the present invention was obtained in the same manner as in Example 3, except that "Nikkor DOP-8N" was used in place of "Nikkol TOP-O" in Example 3. This will be referred to as "Sample 11." Example 12 A carrier of the present invention was obtained in the same manner as in Example 4, except that ``Nikkor DOP-8N'' was used instead of ``Nikkor TOP-O'' in Example 4. This will be referred to as "Sample 12." Samples 1 to 12 obtained in Examples 1 to 12 above
Toner for the electrophotographic copying machine "U-Bix3000" was added to each of these to make a total of 12 types of developer with a toner concentration of 3%, and the developer was shaken for several minutes to become triboelectrically charged, and then subjected to a known blow-off process. A charge amount test was conducted using the method. The results are shown in Table 1.

[Table] Furthermore, when we conducted a photocopying test using each of the above developers using an electrophotographic copying machine "U-Bix3000" (manufactured by Konishiroku Photo Industries Co., Ltd.), the results were good with no fogging up to 100,000 copies. A copy image was obtained. After 100,000 copies, each developer was tested again for the amount of charge. The results are shown in Table 2.

【table】

[Table] Using each of the above-mentioned developers, we conducted similar photocopying tests under a high temperature and high humidity atmosphere of 50°C and 80% relative humidity, and good copy images were obtained up to 100,000 copies. I was able to do that. Comparative Example 1 A carrier was obtained in exactly the same manner as in Example 2, except that the treatment with "Nitsukor TOP-O" was not performed. This will be referred to as "comparative sample 1." A developer was prepared using Comparative Sample 1 in the same manner as described above, and the same charge amount test was conducted, and the charge amount was -17.5 microcoulombs/g.
When a similar photocopying test was conducted using the above developer, fog-free copied images were obtained up to 50,000 copies, but after that, fog occurred and the image quality deteriorated. Furthermore, after 100,000 copies, a charge amount test was conducted and the charge amount was -10 microcoulombs/g.
It was hot. Comparative Example 2 A carrier was obtained in exactly the same manner as in Example 1 except that vinyltriethoxysilane was used in place of "Nitsukol TOP-O" in Example 1. This will be referred to as "comparative sample 2." A similar developer was made using this comparative sample 2,
When a similar photo-copying test was conducted in a high-temperature, high-humidity atmosphere with a temperature of 50°C and a relative humidity of 80%, the image quality of the copied images deteriorated significantly after 20,000 copies were made. Example 13 A carrier of the present invention was obtained in the same manner as in Example 2 except that a styrene-vinylidene chloride copolymer was used as the coating resin. This will be referred to as "Sample 13." Example 14 A carrier of the present invention was obtained in the same manner as in Example 6 except that a styrene-vinylidene chloride copolymer was used as the coating resin. This will be referred to as "Sample 14." Example 15 A carrier of the present invention was obtained in the same manner as in Example 10, except that a styrene-vinylidene chloride copolymer was used as the coating resin. This will be referred to as "Sample 15." Comparative Example 3 The present invention was carried out in the same manner as in Example 2, except that tetra-n-butoxytitanium was used instead of "Nitsukol TOP-O" in Example 2, and styrene-vinylidene chloride copolymer was used as the coating resin. I got a career. This will be referred to as "comparative sample 3." Samples 13 to 15 and comparative sample 3 were heated in a high-temperature, high-humidity atmosphere with a temperature of 50°C and a relative humidity of 80%.
No changes were observed in Samples 13 to 15 after storage for several months, and 10
Even after 10,000 copies, images of good quality were obtained. On the other hand, in comparative sample 3, aggregation occurred after storage. Even when a resin containing a halogen atom is used as the coating resin, the carrier of the present invention has excellent properties.

[Brief explanation of drawings]

FIGS. 1 and 2 are explanatory cross-sectional views schematically showing the structure of particles of the carrier for developing electrostatic images of the present invention. 1... Inorganic carrier core material, 2... Covering layer, 2
A... layer of compound ~ or its salt, 2B...
resin layer.

Claims (1)

[Scope of Claims] 1. A coating layer made of a compound represented by the following general formula or a salt thereof and a resin is formed on the surface of a carrier core material, and the carrier core material of the compound or salt thereof in the coating layer is A negatively chargeable toner carrier characterized in that the proportion of the carrier to the core material is 0.5 to 5% by weight. general formula Here, R: an alkyl group, alkenyl group or aralkyl group having 9 to 18 carbon atoms q: 0 or a positive integer X: -CH ₂ CH ₂ -, [Formula] or [Formula].