JPS6332181B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a one-component developer system for thermal roller fixing used to develop electrical latent images or magnetic latent images in electrophotography or electrostatic printing. The present invention relates to a magnetic toner and a method for producing the same. Conventionally, as an electrophotographic method, U.S. Patent No. 2297691
Specification, Special Publication No. 42-23910 and Special Publication No. 43
A number of methods are known, as described in Japanese Patent Application No. 24748, etc., but in general, a photoconductive substance is used to form an electrical latent image on a photoreceptor by various means, and then the photoreceptor is After developing the latent image using toner and transferring the toner image to a transfer material such as paper as necessary, a copy is obtained which is fixed by heating, pressure, solvent vapor, or the like. Various methods are also known for visualizing electrical latent images using toner. For example, the magnetic brush method described in U.S. Pat. No. 2,874,063, the cascade development method described in U.S. Pat. Many developing methods are known, such as the developing method. As toners used in these developing methods, fine powders in which dyes and pigments are dispersed in natural or synthetic resins have conventionally been used. Furthermore, it is also known to use fine developing powder to which a third substance is added for various purposes. The developed toner image is transferred and fixed onto a transfer material such as paper, if necessary. Methods for fixing toner images include heating and melting the toner using a heater or heated roller to fuse and solidify it to the support, softening or dissolving the binder resin of the toner with an organic solvent, and fixing it to the support, and applying pressure. A method of fixing toner on a support by using a method is known. Toner materials are selected to be suitable for each fixing method, and toners used for a particular fixing method generally cannot be used for other fixing methods. especially,
It is almost impossible to transfer the toner used in the conventionally widely used heat fusion fixing method using a heater to a hot roller fixing method, a solvent fixing method, a pressure fixing method, or the like. Therefore, toners suitable for each fixing method are being researched and developed. However, it is easy to manufacture, has sufficient heat fixing performance, does not cause offset phenomenon to the heating roller, and has stable developing performance and fixing performance even after repeated use. Toners that do not adhere to the surface, do not aggregate or form cakes during storage, and have good storage stability have not yet been obtained. For example, those using a high molecular weight binder resin have a high melting point and do not have good fixing properties. On the other hand, when using a binder resin with a low melting point, offset and wrapping of the paper around the heat fixing roller occur, so to prevent this, a crosslinked polymer was used. However, crosslinked polymers have poor storage stability and are prone to agglomeration and caking, and in the manufacturing process, it is difficult to control crosslinking, resulting in inconsistent quality from lot to lot.Furthermore, they are difficult to grind and difficult to process. The sex was low. Recently, a method has been used in which electrostatic latent images are developed using a one-component developer that contains magnetic fine particles in the toner and does not use carrier particles, but in this case, the toner binding resin is mixed with the magnetic fine particles. dispersibility,
Adhesion, impact resistance, and fluidity of the toner are required. During development by frictional charging between this one-component developer and the developing sleeve roller, the insulating material separates due to impact or use over time, adheres to the sleeve roller due to triboelectric action, and accumulates, making it extremely durable. A practical one-component developer has not yet been obtained due to its poor properties. An object of the present invention is to provide a developing toner that has good heat fixability and does not cause offset or wrap around a heat fixing roller. Another object is to provide a toner with excellent chargeability, impact resistance, and long life. Another purpose is to provide a toner that is easy to work with in manufacturing, is low in cost, easy to control the process, and is stable during storage. It is an object of the present invention to provide a toner that has good developability, heat fixability, and image quality even when used as a magnetic toner for use, and that can be electrostatically transferred. Specifically, the object of the present invention is to heat and knead a toner raw material mixture containing at least a resin having a carboxylic acid and a metal oxide, cool it, and then pulverize it. It is a one-component magnetic toner, and the metal oxides include Zn, Ti,
The toner is an oxide of Ni, Cu, Mn, Co or Fe, and the melt index value of the prepared toner is 1/3 to 1/3 of the melt index value of the resin containing the carboxylic acid before heating and kneading. 30 and a softening point of the toner is 50°C to 200°C. Furthermore, it is an object of the present invention to provide a raw material mixture for a one-component magnetic toner for thermal roller fixing, which comprises at least a resin having a carboxylic acid and a metal oxide of Zn, Ti, Ni, Cu, Co or Fe. Heat-kneaded, cooled and then pulverized to have a melt index value of 1/3 to 1/30 of the melt index value of the resin containing the carboxylic acid, and at a temperature of 50°C to 200°C.
An object of the present invention is to provide a method for producing a one-component magnetic toner for image development for thermal roller fixing, which is characterized by preparing a toner having a softening point of . The carboxylic acid-containing resins applicable to the present invention generally include acrylic acid, methacrylic acid, fumaric acid, maleic acid, succinic acid, itaconic acid, phthalic acid, isophthalic acid, terephthalic acid, cyclohexanedicarboxylic acid, and adipic acid. , sebacic acid, malonic acid, oxalic acid, and their anhydrides as one of the raw materials or as the monomer component of the copolymer. The resin containing carboxylic acid is used as a binder resin for toner, and in order to improve charging characteristics and fixing properties, the resin contains styrene, vinyltoluene, chlorostyrene, dichlorostyrene, bromostyrene, dibromostyrene, divinyl as copolymerized components. A copolymer of benzene, α-methylstyrene, butadiene, etc. is good. The metal oxides applied to the present invention include Zn, Ti, Ni,
Oxides such as Cu, Mn, Co and Fe, such as inorganic pigments and ferrites. As an inorganic pigment
There are ZnO, TiO _2, etc., and as a ferrite
ZnO・Fe ₂ O ₃ , NiO・Fe ₂ O ₃ , CuO・Fe ₂ O ₃ ,
Examples include MnO・Fe ₂ O ₃ and CoO・Fe ₂ O ₃ . Among these metal oxides, those containing zinc were particularly good. Note that a magnetic toner can be obtained by applying the above ferrite. A charge control agent, a colorant, and a fluidity modifier may be added to the toner of the present invention as necessary.
The charge control agent and the fluidity modifier may be mixed (externally added) with the toner. Examples of charge control agents include metal-containing dyes and nigrosine, conventionally known dyes and pigments can be used as colorants, and fluidity modifiers include colloidal silica and fatty acid metal salts. . The one-component magnetic toner according to the present invention is produced by heating and kneading a predetermined raw material mixture to have a predetermined melt index value and softening temperature. On the other hand, when producing magnetic toner by the spray drying method, the dispersibility of magnetic particles tends to be poor, and since the time during which the resin and metal oxide are heated is short, melting due to heating may occur. This method causes almost no decrease in index value compared to the heating kneading method. At this time, the metal oxide in the raw material mixture is 0.1~
It is used in a proportion of 60% by weight, preferably 1 to 50% by weight. The melt index value of the obtained toner is 1/3 to 1/30, preferably 1/5 to 1/15 of the melt index value of the unreacted resin when heated. Suitable for roller fixing.
Here, the melt index value is measured according to the method specified in ASTMD1238 and JISK6760. This value varies depending on the measurement conditions, but for example
Under the conditions of a load of 20 kg and a temperature of 150 DEG C., those having a melt index value in the range of 0.1 to 20, preferably 1 to 7, are unlikely to cause offset or curling. The heating and kneading in the manufacturing process is performed, for example, by heating the toner raw material mixture with a roll mill at 100°C to 200°C (more preferably 150°C to 180°C) for 5 minutes to
Knead for 60 minutes (more preferably 15 to 30 minutes). After cooling, the thickness is 0.1 to 100 μm (more preferably 1 to 1 μm).
The toner is ground to a particle size of 40 μm) to obtain a toner for imaging, which has the above-mentioned melt index value and softening point of 50° C. to 200° C. This toner has good fixability on the heat fixing roller and does not cause offset or wrapping around the heat fixing roller. Furthermore, in the above-mentioned crushing process, since it is brittle, it can be easily crushed and the workability is very good. The effects of the present invention described above can be summarized as follows. This developing toner has excellent heat fixing properties and does not cause offset or wrapping around the heat fixing roller. It can withstand shock during the development process and has a long life. It has excellent fluidity and does not cause adhesion to the carrier, developing sleeve, or photoreceptor surface. It has good charging properties and provides clear images without fog.
The developing performance and fixing performance are stable even when making multiple copies, and the service life is long. Good storage stability without agglomeration or cake formation during storage. Furthermore, even when the toner is made into a one-component developer by containing magnetic particles, the toner has good heat fixability and can be transferred electrostatically. In terms of manufacturing, it has good crushability, is easy to work with, has stable quality, and is easy to control the process.
Manufacturing costs are low. EXAMPLES Hereinafter, the present invention will be specifically explained with reference to Examples, but these are not intended to limit the present invention in any way.
Further, all parts in the examples are parts by weight. The melt index was measured using a Takara Kogyo melt indexer under the conditions of 20 kg load and 150°C. (Example 1) Styrene-isobutyl methacrylate-methacrylic acid copolymer (melt index 16) (copolymer ratio 1:0.7:0.3) 100 parts magnetite (trade name EPT-1000, manufactured by Toda Kogyo) 50 parts ZnO 2 Part Chromium metal complex compound (trade name Cr-2 manufactured by Orient Chemical Co., Ltd.) 4 parts The above mixture was sufficiently kneaded at 180°C for 30 minutes using a roll mill, and then made into toner with a particle size of approximately 3 to 15 microns using a jet pulverizer. . The melt index was 1.6 and the softening point was about 100°C. The amount of triboelectric charge of this toner with a 400 mesh stainless steel screen was -4 μc/g. Next, only this magnetic toner was put into the developing device of a dry type electronic copying machine (product name: NP-5000, manufactured by Canon), and when copies were made, the toner had good fixing properties without being offset to the silicone rubber heating fixing roller. No clear images were obtained. Further, as a durability test of the toner, 30,000 sheets were continuously copied, and as compared to the initial image, copies were obtained that had neither image properties nor fixation properties and had no grand scale color. The amount of triboelectric charge of the toner after 30,000 copies is -
It was 3.5μc/g. (Example 2) 10 parts of the toner of Example 1 was mixed with 90 parts of iron powder carrier (trade name: EFV200/300 made by Nippon Steel Powder) to make a developer, and the same procedure was carried out using this developer to conduct an initial durability test. In all cases, clear images with good fixability were obtained without any offset to the silicone rubber fixing roller. (Example 3) Styrene-isobutyl methacrylate-methacrylic acid copolymer (melt index 20) (copolymer ratio 1:0.8:0.2) 100 parts Ferrite (ZnO Fe ₂ O ₃ ) powder 50 parts chromium metal complex Compound (trade name: Cr-2, manufactured by Orient Chemical Co., Ltd.) 4 parts The above mixture was treated in the same manner as in Example 1 to obtain a magnetic toner. The melt index was 2 and the softening point was about 110°C. of this toner
The amount of triboelectric charge on the 400 mesh stainless steel screen was -4.8 μc/g. The rest was carried out in the same manner as in Example 1, and the same good results as in Example 1 were obtained. (Example 4) Styrene-maleic anhydride-butyl acrylate copolymer (copolymerization ratio 5:1.5:3.5,
Melt index 8) 100 parts ferrite CoO・Fe ₂ O ₃ 50 parts MgO 3 parts metal complex compound (trade name Cr-2 manufactured by Orient Chemical Co., Ltd.) 4 parts The above mixture was treated in the same manner as in Example 1 to obtain a magnetic toner. Ta. The melt index was 1.4 and the softening point was about 130°C. of this toner
The amount of triboelectric charge on the 400 mesh stainless steel screen was -4.3 μc/g. The rest was carried out in the same manner as in Example 1, and almost the same results were obtained. (Example 5) Polyester resin (condensate of fumaric acid and 2,2-bis(4cyclohexanol)propane) (acid value 27, melt index 30)
100 parts Ferrite CoO.Fe ₂ O ₃ 50 parts ZnO 5 parts Metal complex compound (trade name Cr-2 manufactured by Orient Chemical Co., Ltd.) 4 parts The above mixture was treated in the same manner as in Example 1 to obtain a magnetic toner. The melt index was 6 and the softening point was about 80°C. of this toner
The amount of charge on the 400 mesh stainless steel screen was -3.5 μc/g. The rest was carried out in the same manner as in Example 1, and almost the same results were obtained. Next, the toners shown in Examples 1, 3, 4, and 5,
Table 1 shows the results of examining the fixing properties with respect to the heat fixing temperature and the cohesiveness during toner storage. In this fixing property test, fixing operations were performed while changing the surface temperature of a heat fixing roller made of silicone rubber from 130° C. to 200° C. in 10° C. increments. This fixing speed is 120mm/sec
It was hot. The offset to the roller at this time is referred to as "offset." The surface of the copy was rubbed against the obtained image with a paper rag, and the image was marked as "0" if the image was not discolored, and "X" if it was discolored. Further, in the aggregation test, the toner was stored at 45° C. for 4 hours, and the toner with no aggregation was expressed as “0”, and the toner with aggregation was expressed as “X”. For comparison, the same test was also conducted on two types of toners having the following compositions. The linear styrene resin used here does not react with metal oxide Fe ₃ O ₄ during the heating and kneading process of toner production.
Furthermore, the styrene-butadiene copolymer is a crosslinked polymer and does not react with the metal oxide Fe ₃ O ₄ even during the heating and kneading step of toner production. (Comparative example 1) Linear styrene resin (molecular weight 1500) 100 parts Charge control agent 2 parts Fe ₃ O ₄ 50 parts (Comparative example 2) Styrene-butadiene copolymer (manufactured by Nippon Zeon, trade name Nitzpol 2007J) 100 parts Charge Control agent 2 parts Fe ₃ O ₄ 50 parts As can be seen from Table 1, the toners of the examples of the present invention have a wide fixing temperature range, are stable during storage, and do not cause aggregation. On the other hand, the comparative examples are unfavorable from a practical point of view, as the fixing temperature is narrow or too high, and they aggregate during storage. 【table】

Claims (1)

[Claims] 1. A toner raw material mixture containing at least a resin having a carboxylic acid and a metal oxide is heated and kneaded,
A one-component magnetic toner for imaging for thermal roller fixing prepared by pulverizing this after cooling, the metal oxide being an oxide of Zn, Ti, Ni, Cu, Mn, Co or Fe, The melt index value of the prepared toner is 1/3 to 1/30 of the melt index value of the resin containing the carboxylic acid before heating and kneading.
A one-component magnetic toner for image development for thermal roller fixing, characterized in that the toner has a softening point of 50°C to 200°C. 2 Resin with carboxylic acid and Zn, Ti, Ni,
A raw material mixture for a one-component magnetic toner for thermal roller fixing, which contains at least a metal oxide of Cu, Mn, Co, or Fe, is heated and kneaded, and after cooling, it is pulverized to form a melt index of the resin containing the carboxylic acid. A developer for heat roller fixing, characterized in that a toner having a melt index value of 1/3 to 1/30 of the tox value and a softening point of 50°C to 200°C is prepared. Method for producing component-based magnetic toner.