JPH05333607A - Electrostatic charge developing liquid developer - Google Patents

Abstract

PURPOSE:To improve dispersion stability of toner particles and stability of chargeable polarity at the same time by using the liquid developer comprising the toner particles containing a pigment dispersed into a resin in the presence of an acidic pigment derivative and an electrically insulating liquid. CONSTITUTION:Since the acidic pigment derivative is colored, it is preferred to be used for the colorant same as the color, but it is not limited when the black colorant is used, and a suitable amount of it to be added is different according to the kind of pigment to be used, but in general, it is used in an amount of 0.1-30 weight % of the pigment, thus permitting the toner particles to be stabilized in dispersion and charged polarity, and a good image to be formed. Hydrocarbon solvents having a dielectric constant of <=3.5 and a volume resistivity of >=10<-7>OMEGA.cm are used for the insulating liquid, and polyacrylate and the like are used for the resin.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid developer for electrostatic charge development applied to the manifestation of an electrostatic latent image, and more specifically, a toner in which a pigment is dispersed in a resin in the presence of an acidic pigment derivative. The present invention relates to a liquid developer for electrostatic charge development, which comprises particles and an electrically insulating liquid.

[0002]

2. Description of the Related Art As is well known, a liquid developer for electrostatic charge development comprises toner particles dispersed in an electrically insulating organic liquid, and the toner particles are colored, charged, fixable and dispersed. Toner particles are made up of pigments, resins, and other additives that have been added in order to require stability. The following matters are important as such a liquid developer for electrostatic charge development. That is, (1) the dispersion stability of the toner particles is maintained, and (2) the charging polarity of the toner particles is stable.

In order to solve the above problems, for example, as described in Japanese Patent Laid-Open No. 50-17642, dispersion stabilization is achieved by adding a special resin partially soluble in an electrically insulating liquid. Attempts have been made to ensure that. Moreover, dispersion stability is maintained by adding a special activator to the toner as described in JP-A-51-37651 and JP-A-51-47437. Further, Japanese Patent Application Laid-Open No. 50-70024 proposes stabilization of charging by adding a specific metal soap to the toner.

In spite of the above studies, the resistance of the electrically insulating liquid is too low due to the low electric resistance of the activator added for the purpose of stabilizing the dispersion, and further the stability of the charging is stable. The temperature dependence of the liquid resistance of the liquid developer to which metal soap is added for the purpose of practical use is large, and a new problem has arisen in practical use.

[Problems to be Solved by the Invention]

The present invention relates to a liquid developer for electrostatic charge development applied to the manifestation of an electrostatic latent image, and simultaneously improves the dispersion stabilization of toner particles and the stabilization of charging polarity, which have been problems in the past.
It is intended to provide a liquid developer for electrostatic charge development which solves other problems in practical use.

[Means for Solving the Problems]

The present invention relates to a liquid developer for electrostatic charge development applied to the manifestation of an electrostatic latent image, and more specifically, it is electrically insulated from toner particles in which a pigment is dispersed in a resin in the presence of an acidic pigment derivative. The present invention relates to a liquid developer for electrostatic charge development, which comprises a volatile liquid.

As is well known, the acidic pigment derivative used in the present invention is colored so that it is preferably used as a colorant having the same color. For example, when a black colorant is used, it is used. The type of pigment derivative is not limited.

The pigment derivative used in the present invention means organic pigments represented by the following general formulas (1) to (3), and those organic pigments are azo type, phthalocyanine type, quinacridone type, anthraquinone type and perylene type pigments. , Perinone-based, thioindigo-based, dioxazine-based.

General formula (1) Y- (SO ₃ Z / l) n (Y: organic pigment, Z / l; Z is Ca, Ba, Sr, A
1 or Mn, 1 represents the valence of Z. Or Z /
l is a hydrogen atom or Represents the amine. R ^{1 to} R ⁴ ; hydrogen atom or carbon number 1
Represents an alkyl group of 20. However, the case where R ^{1 to} R ⁴ are all hydrogen atoms is excluded. n; an integer of 1 to 4. )

General formula (2) Y- (COO.Z / l) n (Y: organic pigment, Z / l; Z is Ca, Ba, Sr, A
1 or Mn, 1 represents the valence of Z. Or Z /
l is a hydrogen atom or Represents the amine. R ^{1 to} R ⁴ ; hydrogen atom or carbon number 1
Represents an alkyl group of 20. However, the case where R ^{1 to} R ⁴ are all hydrogen atoms is excluded. n; an integer of 1 to 4. )

[0011]

[Chemical 1] General formula (3) (Y: organic pigment, Z / l; Z is Ca, Ba, Sr, A
1 or Mn, 1 represents the valence of Z. Or Z /
l is a hydrogen atom or Represents the amine. R ^{1 to} R ⁴ ; hydrogen atom or carbon number 1
Represents an alkyl group of 20. However, the case where R ^{1 to} R ⁴ are all hydrogen atoms is excluded. n; an integer of 1 to 4. X: represents a hydrogen atom, a halogen atom, a nitro group, an amino group, a sulfone group, a carboxyl group or an alkyl group. )

Examples of the general formulas (1) to (3) include compounds (a) to (d).

[0013]

[Chemical 2] Compound (a)

[0014]

[Chemical 3] Compound (b)

[0015]

[Chemical 4] Compound (c)

[0016]

[Chemical 5] Compound (d)

In the liquid developer for electrostatic charge development of the present invention, the suitable addition amount of the acidic pigment derivative varies depending on the kind of the pigment used, but it is generally in the range of 0.1% by weight to 30% by weight with respect to the pigment. The suitability as a liquid developer for electrostatic charge development, that is, (1) the dispersion stability of toner particles is maintained, (2) the charging polarity of toner particles is stable, and (3) ) A good image could be formed.

As the electrically insulating liquid used in the present invention, a hydrocarbon solvent having a dielectric constant of 3.5 or less and a volume resistance of 10 ⁷ ohm cm or more is used. Preferred examples of these are aliphatic hydrocarbons, aromatic hydrocarbons and mixtures thereof having a boiling point in the range of 150 to 220 ° C,
Isopa G, H, L (made by Esso), Shersol A,
Examples include AB (made by Shell), Naphthesol L, M, H (made by Nippon Oil Co., Ltd.).

The resin used in the present invention includes acrylic resins such as polyacrylic acid ester and polymethacrylic acid ester, polystyrene, polyethylene-acrylic acid copolymer, polyethylene-methacrylic acid copolymer, polyethylene-vinyl acetate copolymer. Polyethylene resins such as polymers, polyvinyl chloride resins, nitrocellulose, alkyd resins, phenol resins, polyester resins, polyvinyl butyral resins, polyisocyanate resins, polyurethane resins, polyamide resins, epoxy resins, etc., but are not limited to these. It is not something that will be done.

A charge control agent may be added to the liquid developer for electrostatic charge development of the present invention. As the charge-imparting agent,
Cobalt naphthenate, zinc naphthenate, copper naphthenate,
Manganese naphthenate, lecithin, cobalt octylate,
What is commonly used, such as zirconium octylate,
You can use it freely.

The method for producing the liquid developer for electrostatic charge development of the present invention includes a method in which a pigment, a resin and an acidic pigment derivative are wet-dispersed in an electrically insulating liquid by a dispersing machine such as a sand mill. 2 rolls of the derivative, 2
There is a method in which the particles are dispersed by a shaft extruder or the like and then wet-dispersed by a sand mill.

[0022]

The present invention will be described in more detail based on the following examples. In addition, "parts" means "parts by weight" and "%" means "parts by weight". In addition, the image evaluation is a nonvolatile content of 1.5.
Liquid developer copier (Savin87
0: manufactured by Sabin Co., Ltd.). The storage stability was evaluated after 50 days using an image obtained by the same method.

Example 1 Polyethylene resin Mitsui High Wax 4202E (manufactured by Mitsui Petrochemical Industry Co., Ltd.) 40 parts Carbon black (Mitsubishi Color Carbon # 44 manufactured by Mitsubishi Kasei Co., Ltd.) 2 parts Compound (a) 0.01 part Isopa G (Exxon) 160 copies

The above mixture was wet-dispersed for 30 hours to obtain a concentrated developer. Isopa G was added to adjust the developer to a solid content of 1.5%. 0.2 part of zirconium octylate was added to 1000 parts of the main developer to prepare a developer for image evaluation. This was put into a liquid development copying machine, which is an image evaluation machine, and the density of the solid portion of the obtained image was measured by a reflection densitometer (Macbeth
As a result of measurement by -918 Macbeth Co., Ltd., a value of 1.38 was obtained. In addition, there was no stain on the non-image area, which was a good result. Furthermore, according to a predetermined storage stability evaluation method,
The image was output after 50 days and compared with the initial one.
No particular change was observed and good results were obtained. The results are shown in Table 1.
Shown in.

Comparative Example A concentrated developer was prepared in the same manner as in Example 1 except that the copper phthalocyanine compound was not added. Subsequent sample preparation was performed in the same manner, a developer for image evaluation was prepared, and an image was obtained according to a predetermined method. As a result, the solid part density and the non-image part stain were almost the same as those in Example 1, but the evaluation of the storage stability was not suitable for practical use in terms of the solid part density and the non-image part stain. I found out.

Example 2 Polyester resin Elitere UE-3210 (manufactured by Unitika Ltd.) 40 parts Blue pigment Rionol Blue FG7350 (manufactured by Toyo Ink Mfg. Co., Ltd.) 1.3 parts Compound (b) 0.1 part Isopa L 160 copies

The above mixture was wet-dispersed for 18 hours to obtain a concentrated developer. After that, Isopa L was added to give a solid content of 1.5.
Adjusted to%. 0.2 part of cobalt naphthenate was added to 1000 parts of the main developer to prepare a developer for image evaluation. The image evaluation results are shown in Table 1. The storage stability evaluation results are also shown in Table 1.
It was shown to.

Example 3 Epoxy resin Epicoat 1004 (manufactured by Shell Co.) 40 parts Yellow pigment Rionol Yellow FG1308 (manufactured by Toyo Ink Co., Ltd.) 1.5 parts Compound (c) 3 parts

The above powder is heated and kneaded by a twin-screw extruder,
Then, the material was roughly crushed with a sample mill and used as a secondary raw material. Secondary raw material 20 parts Shellzol A 80 parts

The above mixture was wet-dispersed for 20 hours to obtain a concentrated developer. After that, it was diluted to a predetermined concentration with Shellzol A, and 1 part of lecithin was added to 1000 parts of the developing solution to obtain a developing solution for image evaluation. The image evaluation results are shown in Table 1.

Example 4 Polyethylene-methacrylic acid copolymer Himilan 1856 (manufactured by Mitsui-Dipon Polychemical Co., Ltd.) 40 parts Red pigment Brilliant Carmine 6BA (manufactured by Toyo Ink Mfg. Co., Ltd.) 0.3 part Compound (d) 0.02 parts Naphthesol M 80 parts

The above mixture was wet-dispersed for 35 hours to obtain a concentrated developer. After that, it was diluted to a predetermined concentration with Naphthesol M, and 0.8 part of manganese naphthenate was added to 1000 parts of 1.5% developer to prepare an image evaluation developer. The image evaluation results are shown in Table 1.

[0033]

[Table 1]

[0034]

The present invention relates to a liquid developer for electrostatic charge development which is applied to the manifestation of an electrostatic latent image according to the present invention, and simultaneously improves the dispersion stabilization of toner particles and the stabilization of charging polarity, which have been problems in the past. It has been possible to provide a liquid developer for electrostatic charge development that solves other practical problems.

Claims (1)

[Claims] 1. A liquid developer for electrostatic charge development comprising toner particles in which a pigment is dispersed in a resin in the presence of an acidic pigment derivative, and an electrically insulating liquid.