JPH04174447A - Liquid developer for static electricity charge development - Google Patents

Abstract

PURPOSE:To offer a static electricity charge development liquid developer which can obtain a superior quality image that is superior in dispersion stability and devoid of image flow and blotting, by using a specific organic acid metallic salt as a dispersing assistant. CONSTITUTION:Pigment, a fixing agent and compounds expressed in a usual formula (I)(R-COO)nM<n+> (In the formula, M indicates alkali metal, alkaline earth metals, zinc, aluminum, manganese and cobalt, and (n) indicates 1-3 integers.) are contained in an electric insulation carrier liquid. As for compounds expressed in the usual formula (I), lithium, natrium, kalium, calcium, magnesium, barium, manganese, aluminum, zinc, cobalt or the like are listed as halogen. Also, as for compounds expressed in the usual formula (I), its alkyl group R carbon atom number is within the range of 1-6, and also being insoluble or hard to dissolve against the electric insulation carrier liquid is important.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a liquid developer for electrostatic charge development, and more particularly to a liquid developer for electrostatic charge development having dispersion stability and excellent development properties.

[Prior Art] Conventionally, liquid developers for electrostatic charge development that use organic pigments as colorants have difficulty dispersing the pigments when the dispersion concentration of the pigments is high, and caking occurs when they are made into concentrated toners. ,
Even when the dispersion concentration is low, there are problems such as sedimentation and aggregation are likely to occur.

[Problems to be Solved by the Invention] In order to solve these problems, methods of using various surfactants as dispersion aids are known; There were problems such as a decrease in image density, image smearing, and blurring.

In addition, surfactants are difficult to adsorb to organic pigments with low surface activity such as disazo yellow and quinacridone pigments, making it difficult to obtain desired electrokinetic properties.

The problem to be solved by the present invention is to have excellent dispersion stability without causing poor dispersion such as caking even when the dispersion concentration of pigment is high like concentrated toner, and to avoid image bleeding and bleeding. An object of the present invention is to provide a liquid developer for developing an electrostatic charge.

Another problem to be solved by the present invention is to provide a dispersion aid that, when used in a color liquid developer, causes less color turbidity in images and does not adversely affect the hue even if it is uncolored or colored. It is to do so.

[Means for Solving the Problems] As a result of various studies in order to eliminate the drawbacks of conventional dispersion aids, the present inventors found that certain organic acid metal salts have been found to be effective in terms of dispersion stability and image quality. It was discovered that it can be an extremely effective dispersion aid, leading to the present invention.

That is, in order to solve the above problems, the present invention provides pigments, fixing agents, and general formula % (1) (wherein R is an alkyl group having 1 to 6 carbon atoms or represents a phenyl group, M is an alkali metal, an alkaline earth metal,
Represents zinc, aluminum, manganese, cobalt, n
represents an integer from 1 to 3. ) A liquid developer for electrostatic charge development is provided, which is characterized by containing a compound represented by:

In the compound represented by the general formula (1) used in the present invention, salt-forming elements include lithium, sodium, potassium, calcium, magnesium, barium, manganese, aluminum, zinc, cobalt, and the like.

The compound represented by the general formula (1) used in the present invention has a carbon atom number in the range of 1 to 6 in the alkyl group R, and is insoluble or poorly soluble in the electrically insulating carrier liquid. This is very important.

When the number of carbon atoms is 7 or more, the solubility in the electrically insulating carrier liquid becomes high, making it difficult to obtain the desired effect.

Examples of the compound represented by the general formula (I) used in the present invention include sodium acetate, magnesium acetate, potassium acetate, calcium acetate, barium acetate, manganese acetate, aluminum acetate, zinc acetate, sodium propanoate, and propanoic acid. Magnesium, calcium propanoate, mankane propanoate, zinc furopanate, potassium butanoate, calcium butanoate, magnesium butanoate, aluminum butanoate, potassium pentanoate,
Magnesium pentanoate, zinc pentanoate, manganese pentanoate, aluminum pentanoate, sodium hexanoate, magnesium hexanoate, calcium hexanoate, cobalt hexanoate, zinc hexanoate, manganese hexanoate, fJI heptanoate) rum, heptane Examples include magnesium acid, calcium heptanoate, aluminum heptanoate, manganese heptanoate, sodium benzoate, calcium benzoate, magnesium benzoate, potassium benzoate, zinc benzoate, and the like. Moreover, hydrates of these compounds can also be suitably used.

The amount of the compound represented by formula (1) used in the present invention relative to the pigment is generally preferably in the range of 0.01 to 20% by weight, particularly preferably in the range of 1 to 10% by weight.

As the pigment used in the present invention, any known pigment can be used without particular restriction. That is, for example, ab pigments such as Hansa yellow cis-azo yellow, permanent yellow, henzimidazolone yellow, permanent red, and naphthol red; phthalocyanine pigments such as phthalocyanine copper; quinacridone pigments such as quinacridone magenta and quinacridone red; isoindolinone pigments ; Examples include carbon black and the like.

As the fixing agent used in the present invention, any known fixing agent used in liquid developers can be used without particular limitation.

Particularly suitable fixing agents include the following fixing agents. That is, (1) a first polymer made of a vinyl polymer soluble in an electrically insulating carrier liquid as described in JP-A No. 5'8-122557;
and a second polymer chain made of vinyl polymerization that is insoluble in the electrically insulating carrier liquid are bonded to each other via urethane bonds, and the molecule as a whole is insoluble in the electrically insulating carrier liquid. Insoluble, non-gelling graft polymer.

(2) A crosslinked polymer soluble in an electrically insulating carrier liquid, which is obtained by crosslinking a vinyl polymer having an active hydrogen atom capable of reacting with an isocyanate group with a polyisocyanate compound, as described in JP-A No. 59-34540. , a twisted chain polymer consisting of a vinyl polymer insoluble in the electrically insulating carrier liquid, which is captured by the crosslinked polymer due to mutual entanglement of molecular chains.

(3) A crosslinked polymer soluble in an electrically insulating carrier liquid (hereinafter referred to as crosslinked ) and a vinyl copolymer insoluble in the electrically insulating carrier liquid, which is obtained by copolymerizing a vinyl monomer having a basic nitrogen atom or an amide group in the molecule and a vinyl acetate monomer; The vinyl copolymer, which is insoluble in the carrier liquid, is a thread-like polymer that is captured by the crosslinked polymer through threads between molecular chains.

(4) An acrylic copolymer soluble in an electrically insulating carrier liquid consisting of methyl methacrylate and an acrylic ester or a long-chain alkylene ester of methacrylic acid proposed in Japanese Patent Application No. 1-162519, and A vinyl copolymer insoluble in the electrically insulating carrier liquid is formed by copolymerizing a vinyl monomer having a basic nitrogen atom or an amide group and a vinyl acetate monomer, and the vinyl polymer insoluble in the electrically insulating carrier liquid is A stitched polymer that is captured in the crosslinked polymer by stitches between molecular chains.

I can list many things.

Note that the amount of these fixing agents used relative to the pigment is usually
A range of 10 to 300% is preferred.

Examples of the electrically insulating carrier liquid include hexane, pentane, octane, nonane, decane, lanticane, and dodecane, as well as "Isopar G" manufactured by Esso Standard Oil Co., Ltd.
”, “Organic solvents sold under trade names such as Isopar HJ, Isopar K, Isopar L, Isopar M, etc., which have a boiling point in the temperature range of 100 to 250°C, and Various aliphatic hydrocarbon solvents having a volume resistivity of 10 9 Ω·cm or more and a dielectric constant of less than 3 can be used.

The liquid developer of the present invention may further contain auxiliary agents such as a charge control agent and a dispersion stabilizer, if necessary. As auxiliary agents such as charge control agents and dispersion stabilizers, those normally used in liquid developers for electrostatic charge development can be used without particular limitation, such as cobalt naphthenate, copper naphthenate, oleic acid, etc. Examples include copper, cobalt oleate, zirconium octylate, cobalt octylate, and polymers of aluminum oxide acylate.

In addition to the pigment, the fixing agent, the compound represented by the general formula (1), and the electrically insulating carrier liquid, the liquid developer according to the present invention further includes auxiliary agents such as a charge control agent and a dispersion stabilizer, if necessary. A concentrated toner having a non-volatile content of about 10% is prepared by uniformly dispersing the mixture with a ball mill, sand mill, attritor, etc.

When used as an electrostatically charged liquid developer, this concentrated toner is diluted with the electrically insulating carrier liquid so that the nonvolatile content is about 0.1 to 2%.

In addition, the compound represented by the general formula (1) is dissolved in an aqueous solvent such as water, a pigment is added to this solution, and after stirring, the solvent is removed by heating and drying, and the resulting powder is used as a coloring agent. A similar effect can be obtained when used as

The liquid developer of the present invention exhibits excellent dispersion stability without causing caking or aggregation even when stored for 6 months or more when the pigment dispersion concentration is high, such as in a concentrated toner. Further, even when concentrated toner is diluted, aggregation and sedimentation hardly occur.

Furthermore, the liquid developer of the present invention does not cause image bleeding or bleeding, and when used in a color liquid developer, the compound of the present invention is a non-colored substance or a substance that does not adversely affect the hue even if it is colored. Therefore, excellent image characteristics such as a clear color image can be obtained without increasing color turbidity.

These effects can be obtained because the compounds of the present invention are insoluble or poorly soluble in the electrically insulating carrier liquid, so they firmly adhere to the pigment surface and become adsorption sites for fixing agents and polarity control agents. This is thought to be to increase the adsorption of the fixing agent and polarity control agent to the colorant.

[Examples] Hereinafter, the present invention will be explained in more detail according to Examples, but the present invention is not limited thereto. In addition,
In the following examples, "parts" and "%" represent "parts by weight" and "% by weight," respectively.

(Manufacture of fixing agent) ■Fixing agent-A “Isopar HJ 150 parts, methyl methacrylate 1
5 parts and 85 parts of 2-ethylhexyl methacrylate were placed in a glass container equipped with a reflux condenser and heated to 80° while stirring.
After heating to C, 0.5 part of benzoyl peroxide was added while maintaining the same temperature, and the mixture was reacted for 6 hours. Furthermore, 90°C
The reaction was continued for 2 hours. After cooling, remove the contents and
A viscous polymer having a viscosity of 30 Stokes was obtained.

131 parts of the polymer was charged into the same reaction vessel as above, and 152 parts of Isopar GJ, 40 parts of vinyl acetate were added.
1 part, 5 parts of N-vinylpyrrolidone and 0.45 parts of azobisisobutyronitrile were added, and the temperature was raised to 80°C.
The mixture was reacted for 6 hours to obtain a white fixing agent dispersion having a non-volatile content of 30%. The fixing agent dispersion thus obtained was designated as "fixing agent A."

■Fixer-B 30.0 parts of lauryl methacrylate, 22.0 parts of butyl methacrylate, 46.6 parts of butyl acrylate, 0.4 parts of hydroxypropyl methacrylate, 1.0 part of methacrylic acid, "Perbutyl DJ (Japan) Polymerization catalyst manufactured by Yushisha) 1.
0 parts and 100 parts of Isopar GJ were charged into a reaction vessel equipped with a nitrogen gas introduction tube, a stirrer, and a cooling tube.
The temperature was raised to 0°C, and the mixture was reacted at 120°C for 8 hours to obtain a polymer having a nonvolatile content of 48.8% and an average molecular weight of 220.000.

Next, the temperature was lowered to 70°C, 0.62 parts of inphorone diisocyanate, 0.05 parts of tin-octylate, and 6 parts of Isopar GJ O were added, and the urethanization reaction was carried out at 70°C for 4 hours. After that, it was cooled and the non-volatile content was 48.6.
A solution of the intermediate containing 0.6% of isocyanate groups was obtained.

106 parts of the solution of the intermediate was charged into the same reaction vessel as above, and further 180 parts of Isopar GJ, 0.4 parts of hydroxypropyl methacrylate, 46.1 parts of methyl methacrylate, and 0.0 parts of azobisisobutyronitrile were added. Add 25 parts, raise the temperature to 80°C, react at 80°C for 5 hours,
A graft polymer solution having a nonvolatile content of 29.2% and an NCO content of 0% was obtained. This graft polymer is a white latte in which a first polymer chain and a second polymer chain are bonded by about 6 urethane bonds per molecule.

It was crap. The fixing agent dispersion thus obtained was designated as "fixing agent B".

■Fixer C: 80 parts of lauryl methacrylate, 10 parts of 2-hydroxyethyl methacrylate, 10 parts of N-vinylpyrrolidone,
1 part of di-tert-butyl peroxide and 14 parts of Isopar GJ were charged into a reaction vessel equipped with a nitrogen gas introduction tube, a stirrer, and a cooling tube, heated to 130°C, and reacted at 130°C for 6 hours. Then, the temperature was lowered to 80°C, and 1.5 parts of inphorone diisocyanate and 0 parts of di-n-butyltin dilaurate were added.
．． 03 parts and 2 parts of Isopar GJ were added, and the urethane reaction was carried out at 80°C for 2 hours, and then cooled to obtain a crosslinked polymer solution with a non-volatile content of 38.2%.

131 parts of the crosslinked polymer was charged into the same reaction vessel as above, and further added with 152 parts of Isopar GJ, 5 parts of 2-hydroxypropyl methacrylate, 40 parts of methyl methacrylate, 5 parts of β-methacryloxyethyl phthalate, and After adding 0.25 part of azobisisobutyronitrile, 8
The temperature was raised to 0°C, and the reaction was carried out at 80°C for 6 hours to reduce the non-volatile content to 3.
A 0% white fixer dispersion was obtained.

The fixer dispersion thus obtained was designated as "Fixer C".

Example 1 [Shimla Fast Yellow O-G F concJ (yellow pigment manufactured by Dainippon Ink and Chemicals Co., Ltd.) 13 parts The above fixing agent C 90 parts Magnesium acetate 1 part Copper naphthenate 2 parts "Isopa G" (manufactured by Exxon Chemical Co., Ltd. Aliphatic Hydrocarbon solvent) 150 parts The above mixture was dispersed in a ball mill for 24 hours, and then diluted with "Isopar G" so that the nonvolatile content was 12% by weight to obtain a concentrated toner. This concentrated toner remained stable without causing caking even after storage for 6 months. Furthermore, 100 parts of the above concentrated toner was diluted with 2000 parts of Isopar GJ to obtain a liquid developer.

Next, a color electrostatic plotter manufactured by Seiko Electronics Co., Ltd.
When an electrostatic latent image was formed on an electrostatic recording paper using EP-4010J and developed with the above liquid developer, a clear yellow image with no image bleeding and no color turbidity was obtained.

Example 2 "Shimla Fast Yellow GRFj (yellow pigment manufactured by Dainippon Ink and Chemicals Co., Ltd.) 10 parts The above agent 8100
Part Zinc Hexanoate 1 Part Zirconium Naphthenate 2 Parts [Isopar G
J 100 parts After dispersing the above mixture in a ball mill for 24 hours, a concentrated toner with a non-volatile content of 13% was obtained in the same manner as in Example 1. This concentrated toner remained stable without causing any caing even after being stored for 6 months. Furthermore, 80 parts of the above concentrated toner was added to "Isopar GJ200".
A liquid developer was prepared by diluting it with 0 parts, and a liquid developer was prepared in the same manner as in Example 1 using a color electrostatic plotter manufactured by Seiko Electronic Industries Co., Ltd.
When developed using 4010J, a clear yellow image without image smearing was obtained.

Examples 3 to 8 Concentrated toners were produced in the same manner as in Example 1, except that each component listed in Table 1 was used instead of each component listed in Example 1. Further, 100 g of each concentrated toner was diluted with 2000 g of Isopar GJ to prepare a developer.

Comparative Example 1 In Example 1, except that magunium acetate was removed,
Concentrated toner and developer were prepared in the same manner as in Example 1.

Comparative Example 2 A concentrated toner and developer were prepared in the same manner as in Example 2, except that zinc hexanoate was omitted.

In Table 1, First Yellow G RF "Lt" Disazo Yellow B material manufactured by Dainippon Ink & Chemicals Co., Ltd., Brilliant Carmine 6 B 2 s a"i;GGO2'' is a disazo yellow pigment manufactured by Hoekist, Germany, First Gen Super Magenta R'' is a quinacridone pigment manufactured by Dainippon Ink and Chemicals, and First Gen Blue GNP is a phthalocyanine pigment manufactured by Dainippon Ink and Chemicals. be.

The results of evaluating each developer are shown in Table 2 below.

Table 2 In Table 2, dispersibility was evaluated by observing the state of the concentrated toner after it had been stored for 6 months. The image condition was evaluated using a color electrostatic plotter rEP-4010j manufactured by Seiko Electronics Industries, Ltd.
The developed image was observed.

From the results shown in Table 2, the liquid developer containing the compound represented by the general formula (I) of the present invention does not cause poor dispersion such as caking even when the pigment dispersion concentration is high as in concentrated toner. First, it is clear that it shows excellent dispersion stability even after being stored for 6 months. Furthermore, it is clear that images obtained using these developers have no image deletion or bleeding and exhibit excellent image quality.

[Effects of the Invention] The liquid developer for electrostatic charge development containing the compound represented by the general formula (I) of the present invention does not cause poor dispersion such as caking even when the pigment dispersion concentration is high as in concentrated toner. It has excellent dispersion stability. Furthermore, images obtained using these liquid developers exhibit excellent image quality without image deletion or blurring.

Furthermore, according to the liquid developer for electrostatic charge development of the present invention, pigments that conventionally could not be used due to poor dispersion, poor storage stability, or problems with image quality can be used as colorants in the liquid developer. .

Agent: Patent Attorney Katsutoshi Takahashi

Claims (1)

[Scope of Claims] 1. Pigment, fixing agent, electrically insulating carrier liquid and general formula [R-COO]_nM^n^+ (wherein R is an alkyl group having 1 to 7 carbon atoms or a phenyl group) , M is an alkali metal, an alkaline earth metal,
represents aluminum, manganese, zinc or cobalt,
n represents an integer from 1 to 3. ) or a hydrate thereof. A liquid developer for electrostatic charge development. 2. The liquid developer according to claim 1, wherein the compound represented by the general formula according to claim 1 is insoluble in the electrically insulating carrier liquid.