JPH0719079B2 - Carrier particles for electrostatic image development - Google Patents

Description

TECHNICAL FIELD The present invention relates to a carrier particle for developing an electrostatic charge image, which is used for developing an electrostatic latent image in electrophotography and electrostatic recording. More specifically, the present invention provides a carrier particle for developing an electrostatic charge image, which comprises a core and a coating resin and has high durability.

In the conventional electrophotographic method, a photoconductive substance such as selenium is used as a photoconductor, an electric latent image is formed by various means, and a toner is formed on the latent image by a magnetic brush development method or the like. A method of adhering and visualizing is generally used.

In this developing step, carrier particles called carriers are used in order to give an appropriate amount of positive or negative amount of electricity to the toner. Carriers are roughly classified into coated carriers and non-coated carriers. However, since the coat carrier is superior in consideration of the life of the developer, various types of coat carriers have been developed and put into practical use.

There are various characteristics required for this coat carrier, and as particularly important characteristics, suitable charging property, impact resistance, abrasion resistance, good adhesion between the core (core material) and the coating material, and the like are mentioned. it can.

Considering the above required characteristics, the conventionally used coat carrier still has a problem to be improved,
The complete one is not known so far. For example, fluorinated vinyl polymers are excellent in chargeability, but have problems in adhesion to the core, and acrylic polymers are satisfactory in mechanical strength and adhesion to the core It is said that there is a problem with sex. In any case, it is the current situation that the use of coating materials having advantages and disadvantages is unavoidable.

OBJECTS OF THE INVENTION In view of such a current situation, the inventors of the present invention have conducted various studies and studies to improve the drawbacks of the conventional products, and as a result, it has been found that the use of a specific coating material can improve various required characteristics of the coat carrier. The inventors have found that it is effective and have completed the present invention.

Therefore, a main object of the present invention is to provide a carrier that overcomes the drawbacks of the conventional products.

Another object of the present invention is to provide a coat carrier which is particularly excellent in positive charging property, has a small change in electric resistance of the core due to coating, and has low temperature and humidity dependency.

SUMMARY OF THE INVENTION The above and other objects of the present invention can be achieved by treating a core material with a tertiary amino group-containing silane compound.

That is, the present invention is characterized by comprising core particles and a coating layer of a tertiary amino group-containing silane compound thereon, wherein the tertiary amino group has a nitrogen atom bonded to a phenyl group and a lower alkyl group. Electrostatic image developing carrier particles The tertiary amino group present in the molecule of the silane compound is effective for imparting good positive charging property and humidity stability to the coat carrier.

Specific examples of the tertiary amino group-containing silane compound used in the present invention include N-methyl-N-phenyl-γ-aminopropyltrimethoxysilane, N-ethyl-N-phenyl-γ-aminopropyltrimethoxysilane, N-
Isopropyl-N-phenyl-γ-aminopropyltrimethoxysilane, Nt-butyl-N-phenyl-γ-
Aminopropyltrimethoxysilane, N-methyl-N-
Phenyl-δ-aminobutyltrimethoxysilane, N-
Ethyl-N-phenyl-δ-aminobutyltrimethoxysilane, N-isopropyl-N-phenyl-δ-aminobutyltrimethoxysilane, Nt-butyl-N-phenyl-δ-aminobutyltrimethoxysilane, bis-
(N-methyl-N-phenyl-γ-aminopropyl)-
Examples thereof include dimethoxysilane and bis- (N-methyl-N-phenyl-δ-aminobutyl) -dimethoxysilane.

On the other hand, the core material used in the present invention is powder of triiron tetraoxide, γ-ferric oxide, MnZn ferrite, NiZn ferrite, Ba ferrite, iron, nickel, cobalt, chromium dioxide, glass beads, etc. A particle size of about 500 μm is used.

As described above, the carrier particles of the present invention are obtained by surface-treating core particles with a tertiary amino group-containing silane compound, and a coating layer is formed on the core particles by chemical bonding or adsorption.

To produce the carrier particles of the present invention, at least one silane compound is combined with a suitable solvent such as alcohol,
Dissolved in dioxane, soak the core particles in the resulting solution, then desolventization, drying, baking at high temperature, or floating the core in a fluidized bed, spray coating the silane compound-containing solution, A method such as drying and then baking at high temperature can be used.

In the above method for producing a carrier, high temperature baking is not always necessary, but from the viewpoint of improving the adhesion strength between the core and the silane compound, it is desirable to perform high temperature baking treatment at about 100 to 200 ° C.

Usually, the coating amount of the silane compound is preferably about 0.001 to 0.5 parts by weight with respect to 100 parts by weight of the core material. For this purpose, the silane compound concentration in the silane compound-containing solution is preferably 1 to 4% by weight. However, it is also possible to use a solution with a lower concentration than this, in which case dipping, desolvation,
The steps of drying, spray coating and drying are repeated.

The carrier of the present invention thus obtained is mixed with toner and used as a developer for an electrostatic latent image.

As the toner, any toner in which a colorant is dispersed in a binder resin and which is generally used in electrophotography can be used and is not particularly limited.

Effects of the Invention When the carrier of the present invention is mixed with a commonly used electrophotographic toner, the carrier can negatively charge the toner, and further, it gives an appropriate saturated charge amount and a remarkably high charging speed. be able to. Further, the change in electric resistance of the core material due to the coating treatment is small, and it becomes possible to obtain a low resistance coated carrier, and it is possible to provide a developer having excellent solid reproducibility. Further, since the carrier is suppressed from being contaminated by the toner based on the coating, the life of the carrier is long, and as a result, a developer having a long life can be provided. Furthermore, the carrier of the present invention is immersed in the solution or the solution of the solution. There are various advantages such as spray coating and the like, or heat treatment if necessary, which enables production in a simple process.

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples.

In each example, all "parts" represent parts by weight.

Example 1 part of N-phenyl-N-methyl-δ-aminobutyltriethoxysilane was dissolved in 50 parts of methanol. 100 parts of spherical ferrite particles having an average particle size of 100 μm were immersed in this solution and heated at 90 ° C. for 1 hour to remove the solvent.
After cooling, coarse particles were removed by sieving to obtain carrier particles for developing an electrostatic charge image of the present invention.

Comparative Example 1 By using γ-aminopropyltriethoxysilane and following the same procedure as in the above-mentioned examples, carrier particles surface-treated with a silane compound containing a primary amino group instead of a tertiary amino group were obtained.

Comparative Example 2 The spherical ferrite particles of Example were used without treatment.

For 100 parts of the carrier particles of the above three examples, styrene-n
Three kinds of developers were obtained by mixing 3 parts of an electrophotographic toner using a -butyl methacrylate copolymer as a binder resin. The charging characteristics and the image characteristics of these developers were examined under the conditions of normal temperature and normal humidity and high temperature and high humidity, and the results shown in the table below were obtained.

The charging characteristics and the image characteristics were obtained under the following methods and conditions, respectively.

In the former, the toner and the carrier were mixed and stirred, and the measurement was performed by the blow-off method. For the latter, the image density and fog density of the fixed image were measured according to the usual method.

Comparative Example 3 Carrier particles for developing an electrostatic charge image were prepared as follows using a secondary amino group silane compound.

1 part of γ-N-methylaminopropyltriethoxysilane was dissolved in 50 parts of methanol. This solution has an average particle size of 100
The solvent was removed by immersing 100 parts of spherical ferrite particles of μm and heating at 90 ° C. for 1 hour. After cooling, coarse particles were removed by sieving to obtain carrier particles containing a secondary amino group. Using this carrier, a developer was obtained in the same manner as described in Comparative Example 2, and the charging property and the image property of this developer were examined. As a result, the charge amount at 23 ° C. and 60% RH was 13.5 μC / g, and the image quality was good. The charge amount at 30 ° C and 90% RH is 8.0 μC / g,
The image quality was large on a white background. The charging characteristics and the image characteristics were obtained under the same method and conditions as in Comparative Example 2.

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Claims (1)

[Claims] 1. A core particle and a coating layer of a tertiary amino group-containing silane compound on the core particle, wherein the tertiary amino group has a nitrogen atom bonded to a phenyl group and a lower alkyl group. Carrier particles for electrostatic image development.