JPH0117577B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a so-called two-component pressure fixing toner, which is used in a dry electrophotographic development method by being mixed with a carrier and fixed under pressure. The magnetic brush two-component development method, which is based on the principle of frictional charging between toner and carrier, can be said to be the most popular method among electrophotographic development methods at present. The fixing method used in this method has generally been heat fixing, but recently pressure fixing, in which the toner powder image is passed between a pair of pressure rollers and fixed, has also been adopted. This pressure fixing does not require any holding time because it is not necessary to heat the copying machine to the temperature required for fixing before starting copying. It has several advantages over heat fixing, such as saving resources because it does not require a heat source. However, the two-component pressure fixing toner currently in use not only has insufficient triboelectric charging properties with the carrier;
The wax, rosin ester, petroleum resin, ethylene-vinyl acetate copolymer resin, etc. contained in the toner as a pressure fixing component are all soft and therefore easily deformed by contact with the carrier. This deformation causes the toner to stick to the surface of the carrier in a compressed manner. This adhesive does not separate as time passes, but rather increases in thickness (this adhesive development is called spent). Not only that, but it also reduces toner fluidity and image quality, causing fogging. The present invention has been made in view of the above circumstances, and its purpose is to provide a two-component pressure fixing toner that does not undergo deformation even when mixed with a carrier and has excellent frictional charging properties with the carrier. be. That is, the present invention resides in a two-component pressure fixing toner comprising a toner core material containing a pressure fixing component and an outer shell of a room temperature curable silicone resin covering the surface of the toner core material. According to the present invention, the above-mentioned occurrence of spent can be significantly improved without adversely affecting the frictional charging property with the carrier. The room temperature curable silicone resin in the present invention is
It is a silicone resin that undergoes a crosslinking reaction when it comes into contact with humid air, resulting in a high molecular weight.For example, RS2410 manufactured by Toray Silicone Co., Ltd.
This applies to RS2411. The resin having a high molecular weight is hard and elastic, so that it can maintain high durability for long-term use. The pressure fixing components contained in the toner core material include higher fatty acids such as stearic acid and lauric acid, polyethylene wax, ethylene-acrylic copolymer resin, ethylene-vinyl acetate copolymer resin,
These include styrene-butadiene copolymer resin, rosin ester, petroleum resin, and polyethylene. In addition, coloring can be achieved by simply adding a colorant to the toner core material, but by mixing it into the silicone resin that forms the outer shell, damage such as spent can be prevented due to the softness of the toner core material. Not only can this be prevented, but also the frictional electrification with the carrier can be considerably improved. As the coloring agent, dyes and pigments such as carbon black, acetylene black, nigrosine, and metal-containing dyes can be used. Furthermore, the triboelectric charging characteristics with the carrier can also be clearly improved by mixing inorganic fine powder such as zinc oxide, aluminum oxide, finely powdered silica, etc. into the silicone resin. As the carrier used in combination with the toner of the present invention, iron oxide powder, glass beads, and other materials such as iron oxide powder and glass beads whose surfaces are coated with a resin that is non-adhesive to the toner can also be used. . Toner is prepared by first mixing a pressure fixing component and a colorant and melting the mixture with heat. Next, cool and crush to 1~
Form a toner core material of 30 μm. Next, the above silicone resin liquid is added to this toner core material and stirred for several minutes using a super mixer. The appropriate amount of silicone resin to be added is 10 parts by weight of a 20% toluene solution of silicone resin per 100 parts by weight of the toner core material. After stirring, dry at room temperature for at least 2 days. As a result, an outer shell of silicone resin is formed on the surface of the toner core material. The present invention will be explained in more detail with reference to Examples below. Example 1 90 parts by weight of low molecular weight polyethylene resin (trade name Hiwax 200P manufactured by Mitsui Petrochemical), ethylene-vinyl acetate copolymer resin (trade name ACP-)
400 manufactured by Allied Chemical Co., Ltd.) and 4 parts by weight of Carbon Black (trade name: Carbon Black #45 manufactured by Mitsubishi Chemical Industries, Ltd.) were premixed for 10 minutes in a super mixer. The mixture was then melt-kneaded in a roll mill for 10 minutes and then cooled.
The cooled product was coarsely ground with a hammer mill, and then finely ground with a jet mill to obtain a black powder of 5 to 30 μm.
For 100 parts by weight of this toner core material, room temperature curing silicone resin (RS2410, manufactured by Toray Silicone Co., Ltd.)
10 parts by weight of 20% toluene melt was added and stirred for 3 minutes using a super mixer. Next, this was dried at room temperature for 3 days (30℃), and after drying, it was classified into 5-20μ
m toner was obtained. Next, 5 parts by weight of the above-obtained toner and 100 parts by weight of Tetoflon-coated carrier were thoroughly mixed and stirred to prepare a developer. This developer is applied to a commercially available zinc oxide type pressure fixing type dry copying machine (product name 5200PPC).
When copying was carried out by applying it to Pitney Bose Co., Ltd., clear images with little fogging were obtained. The amount of charge of this toner can be determined by the blow-off method.
Compared to the initial copying period of 9.2 μc/g, the decrease was small and there was almost no difference in image quality. Example 2 For 100 parts by weight of the toner core material obtained in Example 1,
10 pairs for room temperature curing silicone resin (RS2410)
Nigrosine dye was added at a ratio of 0.05, and 10 parts by weight of a 20% toluene solution in which this was uniformly dispersed was added, and the mixture was stirred for 3 minutes using a super mixer. Next, this was dried at room temperature for 3 days, and after drying, it was classified into 5
A toner of ~20 μm was obtained. Next, a developer was prepared and copies were made in the same manner as in Example 1. The initial charge amount of the toner of this developer was +15.1 μc/g by the blow-off method, and a good image without fogging was obtained. Further, after copying 5,000 sheets, the amount of charge was +15.0 μc/g, showing stable charging characteristics, and the image quality was also comparable to that at the initial stage of copying. Example 3 For 100 parts by weight of the toner core material obtained in Example 1,
Aluminum oxide (average particle size 20 mμ) was added to room temperature-curing silicone resin (RS2410, manufactured by Toray Silicone Co., Ltd.) at a ratio of 10:5, and this was uniformly dispersed.
10 parts by weight of a 20% toluene solution was added and stirred for 3 minutes using a super mixer. Next, this was dried at room temperature for 3 days, and after drying, it was classified to obtain a toner with a size of 5 to 20 μm. Next, a developer was prepared in the same manner as in Example 1, and copies were made. The initial charge amount of the toner of this developer was +12.7 μc/g by the blow-off method, and a good image was obtained. Also, the amount of charge after copying 5000 sheets is +
It was 12.2 μc/g, and there was no difference in image quality compared to the initial stage of copying. Comparative Example 1 To 100 parts by weight of the toner core material obtained in Example 1, 10 parts by weight of a 20% isopropanol/toluene solution of polyamide resin was added and stirred for 3 minutes using a super mixer. Next, this was dried at room temperature (40° C.) for 3 days, and after drying, it was classified to obtain a toner having a size of 5 to 20 μm. Next, a developer was prepared in the same manner as in Example 1, and copies were made. The initial charge amount of the toner of this developer was +6.2 μc/g by the blow-off method, and fogging occurred from the early stage of copying. Also, after making 2000 copies, the image quality deteriorated significantly. The charge amount of the toner was +2.1 μc/g, and aggregation of toner particles was observed. Comparative Example 2 With respect to 100 parts by weight of the toner core material obtained in Example 1,
Nigrosine dye was added to the polyamide resin at a ratio of 10:0.05, and 10 parts by weight of a 20% isopropanol/toluene solution in which the dye was uniformly dispersed was added and stirred for 3 minutes using a super mixer. Next, this was dried at room temperature for 3 days, and after drying, it was classified into 5-20μ
m toner was obtained. Next, a developer was prepared in the same manner as in Example 1, and copies were made. The initial charge amount of the toner of this developer was +15.3μc/g by the blow-off method, and a good image was obtained, but after copying 2000 sheets, the charge amount was +15.3μc/g.
g decreased and fogging occurred. The properties obtained in the above Examples and Comparative Examples are summarized in Table 1 below. It can be seen that the toner in which a specific silicone resin shell is formed on the surface of the toner core material according to the present invention has superior properties both at the initial stage of copying and after continuous copying, compared to the polyamide resin shell of the comparative example. . Note that since polyamide resin is commonly used as a pressure fixing component, it was selected as a comparative example. 【table】

Claims (1)

[Scope of Claims] 1. A two-component pressure fixing toner comprising a toner core material containing a pressure fixing component and an outer shell of a room temperature curing silicone resin covering the surface of the toner core material. 2 Claim 1 having an outer shell in which a dye or pigment is dispersed in a room-temperature curable silicone resin
The two-component pressure fixing toner described in . 3. The two-component pressure fixing toner according to claim 1, which has an outer shell in which at least one of zinc oxide, aluminum oxide, and finely powdered silica is dispersed in a room-temperature curable silicone resin.