JPH03103866A - Developer for electrophotography - Google Patents

Abstract

PURPOSE:To provide the developer which lessens toner splashing and the increase of image staining, such as fogging and to improve the life and stability of the developer by mixing toner particles having an electrostatic charge polarity negative with carrier particles with a specific material. CONSTITUTION:This developer contains the toner particles contg. a resin and coloring agent and basic magnesium aluminum hydroxy carbonate hydrate powder. The toner particles having the electrostatic charge polarity negative with the carrier is used. The basic magnesium aluminum hydroxy carbonate hydrate powder is effectively in improving the image quality and this effect is particularly remarkable when this powder is mixed with the toner particles for the two-component developer having the electrostatic charge polarity negative with the carrier. The good electrostatic charge performance is obtd. in this way and the staining of copies and the degradation in image density are lessened. The good images are thus obtd. regardless of use conditions.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an electrophotographic developer, and more particularly to an electrophotographic developer containing a specific substance.

Prior art> The electrophotographic method is disclosed in U.S. Patent No. 2,297,691,
As disclosed in various publications such as Japanese Patent Publication No. 23910 and Japanese Patent Publication No. 4324748, generally, an electrical latent image of electrostatic charge is formed on a photoreceptor containing a photoconductive material by various means, and then the latent image is is developed as a powder image with toner that has been charged in advance by contact with the carrier or the wall of the developer tank,
After the powder image is transferred to paper or the like as required, it is fixed by heating, pressure, solvent vapor, or the like.

The toner is a powder obtained by dispersing colorants such as dyes and pigments in a resin such as polyester and pulverizing it into particles of about 1 to 30 μm, and the toner itself is supported by electrostatic force on the surface. It is used as a two-part developer by mixing with a magnetic powder called a carrier with a particle size of about 30 to 200 μm, which is transported to the vicinity of the photoreceptor by magnetic force, or it is used as a two-part developer without using a carrier and the function of the carrier is carried out in the toner particles. It is used as an Ikkōbun-type developer by replacing it with magnetic powder contained in .

However, as a means of imparting appropriate chargeability to toner,
Charge control agents such as alloy azo dyes, internal and external additions of inorganic oxides such as finely divided powders, and resin coating of carriers have been known.

<Problems to be Solved by the Invention> However, the effects of these conventional chargeability imparting means are not necessarily satisfactory, and image stains such as fog gradually increase in life tests, or toner scatters within the copying machine. There is. Especially in the case of negatively charged toner,
The amount of charge tends to decrease, and as a result, the amount of reversely charged toner and lowly charged toner increases, and image stains such as toner scattering and fogging have become a particular problem.

As a result of studies to solve this problem, the present inventors have found that by mixing toner particles, especially toner particles that have a negative charge polarity with respect to carrier particles, with a specific substance, excellent life-span stability of copy quality can be achieved. We have discovered that an electrophotographic developer can be obtained, and have reached this discovery.

That is, an object of the present invention is to provide an electrophotographic developer that exhibits less toner scattering, less increase in image stains such as fog, and excellent life stability.

<Means for Solving the Problems> Accordingly, an object of the present invention is to provide toner particles containing at least a resin and a colorant, and a basic magnesium aluminum oxycarbonate hydrate powder. This can be easily achieved using an electrophotographic developer characterized by the following.

The toner particles used in the present invention consist of at least a resin and a colorant.

As the resin content that can be used in the present invention, various known resins suitable for electrophotographic developer toners can be used.

For example, there are styrene resins, styrene-acrylic copolymer resins, polyester citrus resins, epoxy resins, and mixed resins thereof, as well as those having amino groups in their alkyl side chains, among which styrene-based or polyester-based resins The following resins are preferred.

The colorant used in the present invention is not particularly limited as long as it is conventionally used, and to obtain a black toner, a carbon blank or the like is used. Also,
In the case of henna in a color such as blue, red, or yellow, a coloring agent consisting of a dye or pigment of the corresponding color is used.

The content of the colorant is 3 to 20 parts by weight per 100 parts by weight of the resin.
Preferably, it is expressed in parts by weight.

Furthermore, the toner particles used in the present invention may contain known charge control agents, such as metal-containing azo dyes such as Cr and Co, depending on the required chargeability depending on the type of copying machine, carrier, etc.
r, AI! , a salicylic acid metal complex such as Zn, and an alkyl salicylic acid metal complex.

In addition, as a component of the developer of the present invention, additives such as low molecular weight olefin polymers and finely divided silica may be added externally or internally to improve fixing properties and fluidity.

Toner particles can be produced by kneading the above ingredients in a kneader or the like, cooling, pulverizing and classifying.

On the other hand, basic magnesium aluminum hydroxy carbonate hydrate to be mixed with toner particles is represented by the following general formula (1), MgJffq(Oll)r(CO:+)s·mll20
++ (+) (where p, q, r and S are 2p+
It represents an integer satisfying 3q=r+2S, and m represents an arbitrary integer. ) Among these, Mg6^A 2 (OH) 1
3C(h・4H20 or Mgn.sA7!z(OH)
Compounds called hydrotalcites such as ++C03.3.51{20 are conveniently used.

The amount used is preferably 0.01 to 1 part by weight based on 100 parts by weight of the resin contained in the toner particles.

The average diameter of the toner particles is preferably 5 to 20 μm. In the case of a two-component developer, the average particle size of the carrier is 3.
Iron powder, ferrite powder, magnetite powder, magnetic resin carrier, etc. within the range of 0 to 200 μm can be preferably used. In this case, it may be a coated carrier whose surface is coated with a resin or the like. The mixing weight ratio of carrier and 1.ner is 100:1.~100+1'O
is suitable.

In general, in the case of toner particles that have a negative charge polarity with respect to the carrier, toner particles adhere to the surface of the carrier, reducing the charge imparting effect of the carrier, and as the number of times is increased, the charge of the toner particles gradually increases. The amount decreases, and furthermore, a phenomenon in which the toner particles become positively charged is noticeable.
Since the i.ner particles are not strongly attracted to the electrostatic latent image, they adhere to areas other than the latent image on the photoreceptor, staining the image, and causing them to scatter from the photoreceptor into the copying machine.

Therefore, the above-mentioned basic magnesium/aluminum/hydrocarbonate/hydrocarbonate/hydrocarbonate/hydrocarbonate powder has the effect of improving image quality when mixed with any developer, but it has a negative charge polarity with respect to the carrier. Particularly remarkable effects are produced when mixed with toner particles for a bipartite developer having the following.

<Examples> Hereinafter, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited in any way by the following Examples unless the gist thereof is exceeded.

In addition, in the following examples, the term "section" simply means "heavy-view section-1."

Example 1 Styrene-n-butyl acrylate (monomer molar ratio 8
0:20) Copolymer resin 100 parts Low molecular weight polypropylene 3 parts Carbon blank
7 parts chromium containing dye
Two parts were blended, kneaded, crushed and classified to obtain a negatively charged black toner having an average particle size of about 12 μm.

For 100 parts of this black toner, 0.2 parts of fine silica powder (R-972 manufactured by Nippon Aerology/L, (manufactured by 41)) and a hydrotalcite compound (Mg6A j2z (Oll)) were added.
-0.3 part of fatty acid-treated fine powder of 41{zo) was externally added using a Henschel mixer.

A developer was prepared by mixing and stirring 3 parts of the obtained toner and 97 parts of a ferrite carrier coated with a silicone resin having an average particle size of about 100 μm.

Next, when this developer was subjected to a photocopying test using a copying machine up to 20,000 copies, the charging characteristics were stable, toner scattering and fogging were small, and even after 20,000 copies, the developer had excellent copy quality.

Example 2 A photographic test was conducted using a developer manufactured in the same manner as in Example 1, except that the amount of external addition of the hydrotalcite compound was 0.1 part. As a result, the amount of charge was It was stable, and stable copy quality was obtained with little toner scattering and fog increase.

Example 3 A photocopying test was conducted using a developer manufactured in the same manner as in Example 1 except that the amount of external addition of the hydrotalcite compound was 0.05 parts. Stable copy quality with low turbulence was obtained.

Comparative Example 1 A photographic photographic test was conducted using a developer prepared in the same manner as in Example 1 except that the hydrotalcium 1 class 1 compound was not used.

The amount of electricity decreased and the toner density increased with the number of actual copies, fog increased after 4,000 copies, and dirt inside the machine due to toner scattering increased.

<Effects of the Invention> The 1-ner for developing electrostatic images of the present invention has excellent 1-layer performance, such as always exhibiting a moderate and stable electrostatic property, and can withstand high temperatures and high humidity, which have been problems in the past. It provides a good image regardless of the conditions of use, such as less copy staining and lowering of image density during continuous or continuous copying, and provides great industrial benefits.

Claims (2)

[Claims] (1) An electrophotographic developer characterized by containing toner particles containing at least a resin and a colorant, and basic magnesium aluminum hydroxy carbonate hydrate powder. (2) The electrophotographic developer according to claim 1, wherein the toner particles have negative charge polarity with respect to the carrier.