JPH04281463A - Electrostatic charge image developing toner - Google Patents

Abstract

PURPOSE:To effectively prevent toner filming without unnecessarily wearing a photosensitive body and further to improve the cleaning performance of the toner contg. at least a resin, coloring agents and charge control agent so as to obtain a developer having high durability by incorporating boron nitride powder into the above-mentioned toner. CONSTITUTION:The boron nitride powder which itself has a low coefft. of friction is externally added to toner particles. The average grain size of this boron powder is required to be at least smaller than the average of the toner particles. The toner particles are the powder of a prescribed average grain size obtd. by kneading and dispersing the coloring materials and the charge control agent, etc., at need by a kneader, etc., into the binder resin and grinding and classifying the mixture after cooling. Silica, etc., may in some cases be dispersed by a Henschel mixer, etc., into the classified matter. The binder resin for the toner is exemplified by a styrene resin, polyester resin, etc., and the coloring materials include, for example, a carbon black, Aniline Black, etc.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a toner for developing electrostatic images used in fields such as electrophotography. Specifically, the present invention relates to a toner for developing electrostatic images that has good cleaning properties on a photoreceptor and has excellent durability without causing toner filming on the surface of the photoreceptor.

0002

[Prior Art] Conventionally, a two-component developer consisting of a carrier and a toner and a carrier are required as a developer for developing an electrostatic charge image formed on a latent image holding surface such as an electrophotographic photoreceptor. One-component developers are known that do not. The toner particles constituting these developers are normally colored fine particles containing a resin, a colorant, a charge control agent, etc. as components. When a developer made of these toner particles is repeatedly used in a PPC (plain paper copier), etc., the toner remaining on the photoreceptor is not completely removed by cleaning members such as fur brushes and blades, and the copied image may be damaged. It may cause contamination. Further, there is a problem in that a thin film of toner, so-called toner filming, occurs on the surface of the photoreceptor, deteriorating its function.

As an attempt to improve these drawbacks, a method is known in which, for example, a small amount of metal oxide fine powder such as silica or cerium oxide is added to the toner as an external additive. These substances make the toner particles non-adhesive and improve the cleaning properties on the photoreceptor, and also prevent the formation of toner filming on the surface of the photoreceptor by the abrasive action that takes advantage of their hardness. However, the abrasive action of these metal oxides is too strong and may cause unnecessary wear and tear on the photoreceptor. In other words, there have been problems such as streak-like polishing scratches occurring on the surface of the photoreceptor, causing image defects, and severe film thinning, resulting in deterioration of the electrical or optical performance of the photoreceptor.

0004

[Problems to be Solved by the Invention] The present invention has been made to solve the above-mentioned problems with conventional toners, and includes:
The purpose is to provide a toner for developing electrostatic images having the following properties. 1) Even during repeated use, the toner on the photoreceptor has good cleaning properties and no staining of copied images occurs. 2) Preventing deterioration of photoreceptor function due to toner filming without unnecessary wear and tear on the photoreceptor.

[0005]

[Means for Solving the Problems] To achieve the above object, the toner for developing electrostatic images of the present invention is characterized in that it consists of at least nitrogen-boron (hereinafter referred to as BN) powder and toner particles. It is. That is, the gist of the present invention is that by externally adding BN powder, which itself has a low coefficient of friction, to toner particles, the cleaning properties of toner particles on a photoreceptor can be significantly improved;
There is no deterioration of the photoreceptor due to excessive polishing, and toner filming can be prevented. The average particle size of the BN powder to be added to the toner particles needs to be at least smaller than the average particle size of the toner particles, but it is usually 10 μm or less, preferably 5 μm or less, and particularly preferably 3 μm or less. be.

On the other hand, toner particles are powders with an average particle size of 5 to 20 μm obtained by kneading and dispersing a colorant and, if necessary, a charge control agent in a binder resin using a kneader or the like, cooling, pulverizing, and classifying. If necessary, silica or the like may be dispersed in the classified material using a Henschel mixer or the like. Various known materials can be used as these toner components. Examples of the binder resin for toner include polystyrene, styrene-acrylic acid ester copolymer,
Including styrene resins such as styrene-methacrylic acid ester copolymer and styrene-butadiene copolymer, polyester resin, epoxy resin, phenol resin,
Examples include coumarone resin, chlorinated paraffin, xylene resin, vinyl chloride resin, polyethylene, and polypropylene, and particularly preferred resins for use in the present invention include styrene resin, polyester resin, and epoxy resin. can. Moreover, the above resins are not limited to being used alone, but can also be used in combination of two or more.

[0007] There are no particular restrictions on the colorant, but examples include carbon black, aniline black, quinacridone magenta, rhodamine B, brilliant carmine 6B,
Examples include phthalocyanine blue, Victoria blue, industhrene blue, phthalocyanine green, malachite green, benzidine yellow, Hansa yellow, and quinoline yellow. The amount used is preferably 0.1 to 30 parts by weight, particularly preferably 0.5 to 10 parts by weight, per 100 parts by weight of the binder resin. In addition, when two or more types of colorants are used together, the above range is also suitable. All known charge control agents can be used. For example, nigrosine dye for positively charging properties,
There are quaternary ammonium salts, styrene/aminoacrylate copolymers, polyamine resins, etc.Azo dyes containing metals such as chromium, cobalt, aluminum, iron, etc. are used for negatively charging properties.
Metal salts of alkyl salicylic acids are known. The amount used varies depending on the type of charge control agent, but the resin 100
0.1 to 10 parts by weight, more preferably 0 parts by weight
．． 5 to 5 parts by weight is preferable.

[0008]Furthermore, magnetic fine powder can be contained in the toner for the purpose of improving the developing mechanism or image quality. Examples of the magnetic fine powder include alloys or compounds containing ferromagnetic elements such as ferrite and magnetite, and the magnetic fine powder has an average particle size of 0.05 to 0.05.
It can be used in the form of a 1 μm fine powder dispersed in a resin in an amount of up to 70% by weight. In addition, it is also possible to add various auxiliary agents such as plasticizers and release agents to the toner for the purpose of adjusting thermal properties, physical properties, etc. Examples include low molecular weight polyolefin for improving offset properties and colloidal silica for improving fluidity. The appropriate amount of addition is 0.1 to 10 parts by weight per 100 parts by weight of the resin.

When the toner of the present invention is mixed with a carrier and used as a two-component developer, conventionally known carriers such as iron powder, ferrite powder, and magnetite powder with a particle size of about 30 to 200 μm are used as the carrier. can. Also,
Those whose surfaces are coated with silicone resin, alkaline resin, fluororesin, etc. or a mixture of these resins can also be suitably used. The mixing weight ratio of carrier and toner is preferably 100:1 to 100:10.

<Examples> Examples of the present invention will be described below, but the present invention is not limited thereto. In the examples, "parts" indicate "parts by weight." [Example 1] A toner having the following composition and an average particle size of 10
．． Particles of 3 μm were obtained. Styrenic resin (“TB-1000” manufactured by Sanyo Chemical Co., Ltd.) 90 parts Carbon black (“#44” manufactured by Mitsubishi Chemical Co., Ltd.)
8 parts Quaternary ammonium salt (“Bontron P-51” manufactured by Orient Chemical Co., Ltd.)
The two-part toner particles were prepared by thoroughly mixing the above components, followed by hot kneading with an extrusion kneader, pulverizing with an air jet type pulverizer, and classifying. For 100 parts of this toner particle, 0.3 part of BN fine powder ("MW5" manufactured by Union Carbide Co., Ltd.) and 0.3 part of magnetite fine powder ("E
A toner sample was prepared by adding 0.5 part of PT-1000 (manufactured by Toda Kogyo Co., Ltd.) using a mixer. Ferrite powder coated with a fluororesin and having an average particle size of 70 μm was used as a carrier, and mixed with the toner sample. A developer was prepared.The toner content in the developer at this time was 4%.

Furthermore, when this developer was used for development in a copying machine using an OPC (organic photoconductor) as a photoreceptor, extremely clear copies were obtained. Approximately 50,000 sheets were photographed using this developer, and the following results were obtained. 1) Changes in image density and increases in fog were small throughout. 2) No staining of the image due to poor cleaning performance was observed. 3) No image defects occurred due to polishing scratches on the photoreceptor. 4) No toner filming was formed on the surface of the photoreceptor. As described above, it has been found that the electrostatic image developing toner of the present invention has extremely excellent durability. [Comparative Example 1] A developer was prepared in the same manner as in Example 1, except that 0.3 part of the BN fine powder used in Example 1 as an external additive was used as a toner sample, and evaluated by a continuous photographing test. I did it. As a result, after about 25,000 sheets were printed, streak defects due to polishing scratches on the photoreceptor became severe, and the quality of the copies obtained was also quite poor.

[Example 2] A product with an average particle size of 10.4 μm was prepared in exactly the same manner as in Example 1, except that the quaternary ammonium salt was replaced with 1 part of a chromium-containing dye (“Bontron S-34” manufactured by Orient Chemical Co., Ltd.). Toner particles were obtained. This toner particle 1
00 parts, 0.4 part of BN fine powder ("HCP" manufactured by Union Carbide) and 0.4 part of silica fine powder ("Aerosil R9")
A toner sample was prepared by adding 0.3 part of 72" (manufactured by Degussa) using a mixer. Ferrite powder coated with silicone resin and having an average particle diameter of 100 μm was used as a carrier, and mixed with the toner sample to form a developer. The toner content in the developer at this time was 3% by weight.Furthermore, when this developer was used for development in a copying machine using Se as a photoreceptor, extremely clear copies were obtained. When we photographed approximately 50,000 sheets using this developer, 1) there was very little fogging before and after photographing. 2) There was no contamination of the image quality due to poor cleaning performance. 3) There were not many polishing scratches on the photoreceptor. 4) No toner filming was observed on the surface of the photoreceptor. The above results were obtained.

[0013]

As described above, the electrostatic image developing toner of the present invention can effectively prevent toner filming without unnecessary wear on the photoreceptor. Moreover, the toner cleaning performance is also improved. Therefore, by using the electrostatic image developing toner of the present invention, a highly durable developer can be obtained.

Claims (1)

[Claims] 1. A toner for developing an electrostatic image, which is obtained by adding boron nitride powder to a toner containing at least a resin, a colorant, and a charge control agent.