JP2632237B2 - Non-magnetic one-component development method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial applications]

The present invention relates to a contact type non-magnetic one-component developing method for developing an electrostatic latent image using a non-magnetic toner.

[Prior art]

Conventional methods of developing using an electrostatic latent image and toner are roughly classified into a two-component developing method using a two-component developer mainly composed of a toner and a carrier, and a one-component developing method using only a toner. There is a one-component developing method using a developer, and various proposals have been made for each developing method. The two-component developing method using a non-magnetic toner and a carrier is
There are the following disadvantages as compared with the one-component developing method. A toner concentration sensor for controlling the mixing ratio between the toner and the carrier is required. The life of the developer is short. Attention must be paid to handling such as a stirring mechanism of the developer, and a device such as the developer becomes large. In addition, the following points can be cited as disadvantages of the one-component system. The charging member is a developing roll or a blade, and has a lower charging stability and a lower charging ability than a carrier. The precision of the developing machine for uniformly forming the magnetic brush is required. In the case of a magnetic toner, transferability, fixability, environmental characteristics, and damage to a photoconductor are inferior to non-magnetic toner. Considering these problems comprehensively and considering the miniaturization of the apparatus, etc., the one-component developing method using non-magnetic toner is considered to be extremely effective. Developing methods have attracted attention, and some of them have been put to practical use. The one-component developing method using a non-magnetic toner includes a contact-type non-magnetic one-component developing method in which a developing roll carrying a developer is brought into contact with a photoreceptor having an electrostatic latent image to perform development. There is a non-contact type non-magnetic one-component developing method in which a certain gap is provided between the developing rollers to fly the toner on a developing roll and develop the toner. In the non-contact type non-magnetic one-component developing method, since the developer is frictionally charged only by the charging member, the mechanical load on the developer is smaller than that in the contact type developing method. Because of the different flight properties of the agents, they had the disadvantage of being susceptible to the environment. On the other hand, in the contact-type non-magnetic one-component developing method, the toner on the developing roll comes into contact with the photosensitive member having the electrostatic latent image, so that the developing property is extremely good.

[Problems to be solved by the invention]

However, in the contact type non-magnetic one-component developing method,
On the other hand, not only frictional charging by the charging member until the toner is formed as a thin layer on the developing roll, but also frictional force due to the difference in peripheral speed with the photoreceptor, the mechanical load is lower than in the non-contact method. Extremely large. Therefore, in the non-magnetic one-component developing method based on the contact method, it is extremely important to prevent the frictional charging member and the photosensitive member from being fused by contact with each other and not to damage the developing roll, the photosensitive member, and the like. In order to make a developer that does not fuse due to frictional force, it is effective to use a material having a high glass transition temperature for the purpose of making the binder resin of the developer less likely to fuse, but the relationship with the fixing property is effective. It is not practical to use a resin having a high glass transition temperature to solve the problem. Further, in order to prevent the occurrence of scratches on the developing roll and the photoconductor, it is effective to reduce the amount of silica as a post-treatment agent of the toner, but the fluidity of the toner is reduced,
There are adverse effects such as the fact that fusion is more likely to occur. The present invention has been made in view of the above-described circumstances in the related art. Therefore, an object of the present invention is to provide a non-magnetic one-component developing method that uses a contact developing method that is less susceptible to the influence of the environment, and that uses a contact roller that is less susceptible to the influence of the environment. Is to provide.

[Means for Solving the Problems]

The present inventors have intensively studied to solve the drawbacks of the contact-type non-magnetic one-component developing method and to extremely reduce toner fusion to a developing roll and a photoreceptor while obtaining good developing characteristics. As a result, silica, which is added as a post-treatment agent of the toner, is added in an amount larger than the usual amount, and a part of the silica is firmly fixed to the toner surface. It has been found that a non-magnetic one-component developing method with less fusion to the body can be provided, and the present invention has been completed. That is, in the present invention, the developer is supplied to an elastic carrier that carries the developer, the developer is applied by a regulating member so as to form a thin layer on the carrier, and a charge is given to the developer. In a contact-type non-magnetic one-component developing method in which an electrostatic latent image is developed by being brought into contact with a holding member for holding an image, and then transferred to paper, a binder resin and a colorant are mainly used as a developer. Attach a part of hydrophobic silica to the toner,
It is characterized by using a non-magnetic one-component developer in which a part of the developer is held free. Hereinafter, the present invention will be described in detail. FIG. 1 is a schematic structural view of a developing device used in the contact type non-magnetic one-component developing method of the present invention. In the drawing, 1 is a photosensitive drum which is a cylindrical electrostatic latent image holding member, 2 is a hopper, 3 is a developer, 4 is a layer regulating member, 5 is a developing roll having a sleeve-like layer formed on its surface, 6 is a toner supply roll, and 7 is a stirrer. In this developing device, an electrostatic latent image is formed on the photosensitive drum 1 by a known electrophotographic method. A developer 3 is contained in the hopper 2, and the developer 3 is supplied to a developing roll 5 by a layer regulating member 4.
It is carried and transported on the sleeve-shaped layer provided at a constant thickness. The sleeve-like layer is formed of an elastic material such as a synthetic resin, and is provided in contact with the photosensitive drum. Alternatively, a conductive material may be contained in the synthetic resin, and a DC or AC voltage may be applied to the sleeve-like layer. The developer carried by the developing roll 5 is conveyed by the rotation of the developing roll, comes into contact with the photosensitive drum 1 having an electrostatic latent image, and the electrostatic latent image is visualized. The toner constituting the one-component developer used in the above-mentioned method in the present invention contains a binder resin and a colorant as main components, and a known toner is used. As the binder resin, in addition to those conventionally used for powder toners for electrophotography, all resins that could not be used in terms of polarity controllability and the like can be used. For example, polystyrene,
Polyester, ethylene-vinyl chloride copolymer, ethylene-vinyl acetate copolymer, polyamide, polyethylene,
Maleic acid resin, acrylic resin, epoxy resin, xylene resin, coumarone resin, ketone resin, petroleum resin, phenol resin and the like can be mentioned. As the coloring agent, any known coloring agent can be used. Examples include carbon black, acetylene black, lamp black, channel black, farnal blue, permanent blue, nigrosine blue, phthalocyanine blue, rose bengal, CI Pigment Red 122, CI Pigment Yellow 12, and the like. These colorants are appropriately blended in the binder resin in a range of 1 to 10 parts by weight. The toner may optionally contain other components, for example, a known charge control agent. The toner having a particle size smaller than about 30 μm is preferably used. In the present invention, the toner is mixed with hydrophobic silica. At this time, a part of the hydrophobic silica is fixed to the toner particles, and a part of the hydrophobic silica is kept in a released state. In order to fix a part of the hydrophobic silica to the toner and to keep a part of the toner in a free state, the hydrophobic silica is added in an amount larger than the usual amount, preferably 0.6% or more per weight of the toner. Done. In this case, the ratio of the hydrophobic silica to be fixed to the toner and the hydrophobic silica to be kept free is in the range of 40:60 to 90:10. In order to fix a part of the hydrophobic silica to the toner and to fix a part thereof, it is necessary to use a conventional powder mixer such as a mixer such as a Henschel mixer or a super mixer, or a so-called surface modification such as a hybridizer or an ongmill. It can also be performed using a quality machine. When a powder mixer such as a Henschel mixer or a super mixer is used, a relatively long processing time is required. The effect is obtained and the efficiency is improved. For example, first, a predetermined amount of hydrophobic silica is added to the toner, and the mixture is mixed by the above mixer until the hydrophobic silica adheres to the surface of the toner particles. Then, the remaining amount of the hydrophobic silica is further added to the toner. Add and mix briefly under mild mixing conditions. The hydrophobic silica used in the present invention can be easily obtained by replacing the terminal silanol group of a normal hydrophilic silica molecule with an organic silicon halide or alcohol. Such hydrophobic silica fine powder can be easily obtained as a commercial product (for example, Aerosil R-972 manufactured by Nippon Aerosil Co., Ltd.).

[Action]

To reduce the amount of developer that is fused to the roll and the photoconductor, increase the amount of silica added in the post-treatment of the toner, and cover the toner surface with a non-fusible substance such as silica that is difficult to fuse. It is effective, but if the amount of silica added is increased, the chargeability of the toner due to the environment changes significantly,
The free silica easily causes scratches on the surface of the photoreceptor, and adverse effects due to reduced fusion are also generated. However, according to the present invention, hydrophobic silica is used as silica, and the amount of addition is increased, and a part of the added hydrophobic silica is fixed to the toner surface, and the surface area of silica is reduced by embedding, thereby reducing the surface area of silica. As a result, it is possible to provide an effective fusion preventing means while preventing the environmental characteristics from being deteriorated. In addition, since the amount of silica released at the same time is reduced, it is possible to effectively prevent the occurrence of scratches on the surface of the photoconductor caused by the released silica. In addition, by increasing the amount of hydrophobic silica added,
It is conceivable that the chargeability of the toner greatly depends on the chargeability of the silica.In such a case, silica having different chargeabilities, for example, silica having strong positive polarity and silica having strong negative polarity are mixed. It can also be used.

【Example】

Hereinafter, the present invention will be described with reference to examples, but is not limited thereto. Example 1 As a non-magnetic toner, a raw material was mixed, melt-kneaded, and pulverized and classified according to the following composition (parts by weight) to obtain a toner having an average particle diameter of 12 μm. To this toner, 0.4% of hydrophobic silica H2000 manufactured by Hoechst was added, and the mixture was stirred for 30 minutes while passing cooling water with a Henschel mixer to fix silica on the toner surface. Further, the same silica was added at 0.2% and stirred for 2 minutes to obtain a target toner. Styrene acrylic copolymer (TTR-563, manufactured by Fujikura Kasei) 97
Part Polypropylene wax (Viscol 550P, manufactured by Sanyo Chemical) 2 parts Charge control agent (Bontron S34, manufactured by Orient Chemical) 1 part A commercially available non-magnetic one-component printer (manufactured by Ricoh, LP1060-SP3) ), A print test was performed, and even when 10,000 sheets were printed, good results were obtained without any fusion of the toner to the developing roll and the photoreceptor, generation of scratches on the photoreceptor surface, and the like. . When the surface of the toner particles was observed with an electron microscope, the surface of the toner particles was smooth, and a state in which much silica was embedded in the surface of the toner particles was observed. Comparative Example 1 A toner was obtained by melt-kneading and pulverizing and classifying in the same manner as in Example 1. 0.6% of the same hydrophobic silica as in Example 1 was added to the obtained toner, and stirred with a Henschel mixer for 2 minutes to obtain a toner. In the same manner as in Example 1, a commercially available printer (manufactured by Ricoh Company)
A print test was performed using LP1060-SP3). As a result, toner fusion to the developing roll was observed on about 1000 sheets. After continuing the print test,
From around 5,000 sheets, a defect in a solid black portion caused by a scratch on the photoreceptor was observed. Example 2 As a non-magnetic toner, the following ingredients (parts by weight) were mixed, melt-kneaded, and pulverized and classified to obtain a toner having an average particle diameter of 10 μm. This toner was applied to a surface-modifying device hybridizer manufactured by Nara Machine Co., Ltd. using hydrophobic silica manufactured by Hoechst.
0.8% H2000 / 4 was added, and the mixture was treated for 10 minutes to fix silica on the toner surface. Further, the same silica was added at 0.2% and stirred for 2 minutes to obtain a target toner. Styrene acrylic copolymer (P-599, manufactured by Sekisui Chemical) 96
Part Polypropylene wax (Viscol 550p, manufactured by Sanyo Chemical) 3 parts Charge control agent (Bontron E81, manufactured by Orient Chemical) 1 part A commercially available non-magnetic one-component printer (manufactured by Ricoh, LP1060-SP3) ), A print test was conducted. As a result, even when 15,000 sheets were printed, no toner was fused to the developing roll and the photoreceptor, and no damage was caused on the photoreceptor, and good results were obtained. When the surface of the toner particles was observed with an electron microscope, the surface of the toner particles was smooth, and a lot of silica was embedded in the surface of the toner particles.Some of the silica particles appeared to float on the surface. It was observed to be present in a state. Comparative Example 2 To a toner obtained by melt-kneading and pulverizing and classifying in the same manner as in Example 1, 0.4% of hydrophobic silica H2000 manufactured by Hoechst Co. was added, and the mixture was stirred for 30 minutes while passing cooling water through a Hensial mixer. Silica was fixed on the surface. In addition, the same silica was added at 0.
Toner was obtained by adding 7% and stirring for 2 minutes. In the same manner as in Example 1, a commercially available printer (manufactured by Ricoh Company)
A print test was performed using LP1060-SP3).
As a result, toner fusion to the developing roll was observed on about 1000 sheets. When the print test was further continued, a defect in a solid black portion caused by a scratch on the photoreceptor was observed from around 5,000 sheets. Comparative Example 3 To a toner obtained by melt-kneading and pulverizing and classifying in the same manner as in Example 1, 0.6% of hydrophobic silica H2000 manufactured by Hoechst Co. was added, and the mixture was stirred for 30 minutes while passing cooling water through a Henshal mixer. Silica was fixed on the surface. In addition, the same silica was added at 0.
A toner was obtained by adding 05% and stirring for 2 minutes. In the same manner as in Example 1, a commercially available printer (manufactured by Ricoh Company)
A print test was performed using LP1060-SP3).
As a result, a defect in the solid black portion caused by deterioration of the fluidity of the toner was observed from around 5,000 sheets.

【The invention's effect】

In the present invention, as described above, a part of the hydrophobic silica is fixed to the toner surface and a part thereof is present in a free state, so that the toner does not fuse on the developing roll or the photoconductor surface, In addition, it is possible to effectively prevent the chargeability of the toner from being greatly changed due to the environment, and to prevent the surface of the photoconductor from being damaged by free silica. Therefore, according to the present invention, it is possible to obtain a print having good image quality stably with respect to environmental changes.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of a one-component developing apparatus for carrying out the present invention. 1 photoreceptor drum, 2 hopper, 3 developer
4 ... layer regulating member, 5 ... developing roll, 6 ... toner supply roll, 7 ... stirrer.

Claims (2)

(57) [Claims] An electrostatic latent image is supplied by supplying a developer to an elastic carrier that carries the developer, applying the developer by a regulating member so as to form a thin layer on the carrier, and applying an electric charge. In a contact-type non-magnetic one-component developing method in which an electrostatic latent image is developed by being brought into contact with a holding member that holds the toner, and then transferred to paper, a toner mainly comprising a binder resin and a colorant is used as a developer. Is a non-magnetic one-component developer in which a part of the hydrophobic silica is fixed and a part thereof is kept in a released state, and the ratio of the hydrophobic silica to be fixed to the toner and the hydrophobic silica to be kept in the free state is as follows. A non-magnetic one-component developing method using a ratio in the range of 40:60 to 90:10. 2. The method according to claim 1, wherein the hydrophobic silica is used in an amount of 0.6% per unit weight of the toner.
2. The non-magnetic one-component developing method according to claim 1, wherein a developer added in an amount of at least 1% is used.