JPH11184169A - Yellow liquid developer for electrostatic charge development - Google Patents

Abstract

[PROBLEMS] To provide a yellow liquid developer for electrostatic charge development having excellent storage stability and good redispersibility. SOLUTION: In a liquid developer for electrostatic charge development in which toner particles containing a colorant and a binder resin as main components are dispersed in a carrier liquid having a high insulating property and a low dielectric constant, C.I.
A yellow liquid developer for electrostatic charge development, comprising I. Pigment Yellow 97. The yellow liquid developer of the present invention does not cause poor dispersion such as caking and shows excellent dispersion stability even when the pigment has a high concentration of dispersion as in a concentrated toner. Also, when the concentrated toner is diluted and left in a state of a developer for a long period of time, it shows good redispersibility.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a yellow liquid developer used for developing an electrostatic latent image formed by an electrophotographic system or an electrostatic recording system.

[0002]

2. Description of the Related Art Color liquid developers used in electrophotography such as electrophotography and electrostatic recording are used in an electrically insulating carrier liquid having a high electric resistance and a low dielectric constant, such as an aliphatic hydrocarbon solvent. Is a dispersion of toner particles containing a binder, a colorant, an additive, and the like. Usually, a natural or synthetic resin is used as the binder, a pigment or dye is used as the colorant, and a metal is used as the additive. It is obtained by mixing a dispersant such as a soap with the carrier liquid, kneading the mixture uniformly and preparing a concentrated toner, and then diluting the concentrated toner in the carrier liquid. In order to obtain a color image using such a color liquid developer, an electrostatic latent image is formed on an electrophotographic photosensitive member or an electrostatic recording paper according to a conventional method, and then developed with a developer of a different color. .

A color image is obtained by repeating this process for each color. The color image thus obtained is obtained by stacking toner particles in the liquid developer of each color corresponding to each color of the original image. Yellow liquid developer is often used in the final stage of development,
For this reason, excellent transparency is required together with a clear hue.

[0004] Pigments for yellow liquid developers satisfying such requirements include CI Pigment Yellow 12 and CI Pigment Yellow 12.
CI Pigment Yellow 13, CI Pigment Yellow 14
However, when a concentrated toner is formed by using such a pigment, caking occurs or the settled toner particles are easily aggregated, and there is a problem in redispersibility.

In addition, in the conventional liquid developer using a disazo yellow pigment, when heated after development in order to improve the fixability of the toner image after development, harmful dichlorbenzidine is generated. He also had points.

In order to solve such problems, we have proposed an improved yellow liquid developer in Japanese Patent Application Laid-Open No. 4-335653. However, since disazo yellow is used as the main pigment, concentrated toner is used. However, problems such as formation of caking, sedimentation and coagulation did not reach a satisfactory level.

[0007] Further, we have proposed an improved yellow liquid developer which does not generate harmful dichlorobenzidine in Japanese Patent Application Laid-Open No. 5-19538, but it is still satisfactory in both image characteristics and stability over time. I did not reach the level I could do. As described above, the conventional yellow liquid developer has not yet achieved sufficient effects in terms of toner characteristics and hygiene.

[0008]

The problem to be solved by the present invention is that even when a so-called concentrated toner having a high pigment dispersion concentration is used, poor dispersion such as caking does not occur.
Another object of the present invention is to provide a yellow liquid developer having a good re-dispersibility of the sedimented toner and an excellent dispersion stability when the dispersion concentration of the pigment is relatively low, that is, when a so-called developer is used. .

Another object of the present invention is to improve the fixability of a toner image after development, so that even when heated after development, no harmful dichlorobenzidine is generated, which is excellent in terms of hygiene. To provide an improved yellow liquid developer.

[0010]

Means for Solving the Problems The present inventors have made intensive studies to solve the above-mentioned problems, and as a result, have found that the above-mentioned problems can be solved by selecting a specific pigment as a coloring agent. The present invention has been reached.

That is, in order to solve the above-mentioned problems, the present invention provides a toner containing a colorant and a resin as main components with a high insulating property.
A colorant in a liquid developer for electrostatic charge development dispersed in a carrier liquid having a low dielectric constant,

Embedded image A yellow liquid developer for electrostatic charge development, which comprises a pigment represented by the formula:

The pigment represented by Chemical Formula 1 used in the present invention is a kind of Hansa yellow pigment, and is a CIPIGMEN pigment.
As T YELLOW 97, any of those commercially available under the trade names such as Novo Palm Yellow FGL (manufactured by Hoechst) Yellow 950 (manufactured by Arimoto Kagaku) and Shimla First Yellow 4186 (manufactured by Dainippon Ink and Chemicals, Inc.) Although it can be suitably used, in order to more effectively achieve the object of the present invention, it is preferable to select a grade having improved transparency by rosin treatment or the like.

In order to achieve the object of the present invention, it is desirable to use a pigment represented by the chemical formula 1, but other yellow pigments can be used together as long as the effects of the present invention are not lost. Representative examples thereof include, for example, Disazo Yellow AAA (CIPigment Yellow 12), Disazo Yellow AAMX (CIPigment Yellow 13), Disazo Yellow AAOT (CIPigment Yellow 14), Disazo Yellow AAOA (CIPigment Yellow 17), and Disazo Yellow AAPT (CIPigment Yellow). 55),
Disazo Yellow 87 (CIPigment Yellow 87), Disazo Yellow 170 (CIPigment Yellow 170, benzimidazolone-based disazo yellow pigment (CI PigmentYell)
ow 180), Crayon Orange (CIPigment Orange 1
5), Vulcan Orange (CIPigment Orange 16), Disazo Orange PMP (CIPigment Orange 13), Disazo Orange TMP (CIPigment Orange 34) and the like.

In the present invention, the pigment may be used as a colorant as it is. However, in order to improve the fixability of a developed image, when a pigment prepared by melting and kneading a pigment in advance with a resin is used, heat fixing is used. It has a more special effect in that sometimes it does not generate harmful dichlorbenzidine. The resin in this case is a thermoplastic resin that is insoluble in the dispersion medium unlike the binder resin, and specific examples thereof include, for example, styrene resins (picosticks A75, D75, D100, etc., manufactured by Esso Chemical Industry Co., Ltd.), Maleic resin [Arakawa Chemical Industry Co., Ltd. ester gum M-90, 100,
Marquid No1,2,5,6,8, Beccasite 1110,1111, F-231,1120 etc., manufactured by Dainippon Ink and Chemicals, Inc., phenolic resin [Super Beccasite manufactured by Dainippon Ink and Chemicals, Inc.] 1001,3011, Beccasite 1100,1123
Epoxy resin [Epiclon 1050, 4055, 7050 manufactured by Dainippon Ink and Chemicals, Inc., Epicoat 1001, 1004, 1007 manufactured by Shell Sekiyu KK], ketone resin [Aron KR- manufactured by Toa Gosei Chemical Industry Co., Ltd.] SS etc.), butyral resin [ESREC BM-1,2 etc., manufactured by Sekisui Chemical Co., Ltd.],
Examples include methacrylic resins (Dianal BR-64, 77, 85, 90, 106, etc., manufactured by Mitsubishi Rayon Co., Ltd.), polyester resins and the like. These can be used alone or as a mixture of two or more. The resin used for melt kneading may be any insoluble in the organic solvent constituting the carrier liquid, but when using a carrier liquid having a solubility parameter of 7.5 or less, the resin used has a solubility parameter of 8.5 or more. It is preferable to use

The binder resin used in the present invention includes:
Known ones used for liquid developers are used without any particular limitation. For example, butadiene rubber, styrene-butadiene rubber, cyclized rubber, rubbers such as natural rubber, styrene resin, vinyltoluene resin, acrylic resin, methacrylic resin, polyester resin, polycarbonate resin, polyvinyl acetate Synthetic resins such as resin-based resins, rosin-based resins, hydrogenated rosin-based resins, alkyd resins including modified alkyds such as linseed oil-modified alkyd resins, and natural resins such as polyterpenes. In addition, phenol resins, modified phenol resins such as phenol formalin resin, pentaerythritol phthalate, coumarone-indene resins, ester gum resins, vegetable oil polyamide resins, etc. are also useful, and polyvinyl chloride, chlorinated Halogenated hydrocarbon polymers such as polypropylene, synthetic rubbers such as vinyl toluene-butadiene, butadiene-isoprene, and long-chain alkyls such as 2-ethyl exyl methacrylate, lauryl methacrylate, stearyl methacrylate, lauryl acrylate, octyl acrylate Polymers of acrylic monomers having a group or copolymers thereof with other polymerizable monomers (for example,
Styrene-lauryl methacrylate copolymer, acrylic acid-lauryl methacrylate copolymer, etc.), polyolefins such as polyethylene, polyterpenes, and an electrically insulating carrier composed of methyl methacrylate and an acrylate or a long-chain alkyl methacrylate. Acrylic copolymers soluble in the liquid (for example, those described in JP-B-20996) can also be used.

A particularly preferred resin is an amphiphilic resin, which is a resin having both a portion soluble in a dispersion medium and a portion insoluble in a molecule. Examples of such a resin include the following.

A first polymer chain made of a vinyl polymer soluble in an electrically insulating carrier liquid and a second polymer chain made of a vinyl polymer insoluble in the carrier liquid are mutually bonded via a urethane bond. Non-gel graft polymer having a molecular structure and insoluble in the carrier liquid as a whole molecule (for example,
No. 58-122557. A) a cross-linked polymer soluble in an electrically insulating carrier liquid obtained by cross-linking a vinyl polymer having a cross-linking reactive functional group in a molecular side chain, and a vinyl monomer having a basic nitrogen atom or an amide group in the molecule. It consists of a vinyl copolymer insoluble in a carrier liquid obtained by copolymerizing a vinyl acetate monomer, and the vinyl copolymer insoluble in the carrier liquid is a polymer trapped by the crosslinked polymer (for example, JP-A-63-1988). No. 208866). Acrylic copolymer soluble in an electrically insulating medium liquid comprising methyl methacrylate and an acrylic ester or a long-chain acrylic ester of methacrylic acid described in JP-A-3-9369, and a basic nitrogen atom in the molecule Or a vinyl copolymer insoluble in the insulating carrier liquid obtained by copolymerizing a vinyl monomer having an amide group and a vinyl acetate monomer, wherein the vinyl polymer insoluble in the electrically insulating carrier liquid is entangled in molecular chains. And a chain polymer captured by the polymer.

In the present invention, if necessary, a charge control agent can be used to charge the toner particles. As these charge control agents, conventionally known ones are appropriately used. For example, naphthenic acid, octylic acid,
Metal salts of fatty acids such as oleic acid, stearic acid, isostearic acid and lauric acid, metal salts of sulfosuccinates, metal salts of phosphoric acid esters, metal salts of aromatic carboxylic acids, and metal salts of aromatic sulfonic acids. The use amount of these charge control agents is not particularly limited, but is 0.5 to 5 per 100 parts by weight of the colorant and the binder resin in total.
It is preferred to use parts by weight.

Among these charge control agents, naphthenic acid,
Metal salts of octylic acid are particularly preferred for achieving the objects of the present invention.

In order to improve the charge of the colorant, SiO ₂ , Al ₂ O ₃ , TiO ₂ , ZnO, Ga ₂ O ₃ ,
Metal oxide fine particles such as In ₂ O ₃ , GeO ₂ , SnO ₂ , PbO ₂ , and MgO or a mixture thereof may be added as a charge enhancer. As the electrically insulating carrier liquid, a liquid having a high resistance and a low dielectric constant at room temperature, for example, hexane, pentane,
In addition to octane, nonane, decane, undecane, and dodecane, isoper G, H, K, L, M manufactured by Exxon Chemical Company
100-2 such as organic solvents sold under trade names such as
Various aliphatic hydrocarbon solvents having a boiling point in the temperature range of 50 ° C., a volume resistivity of 10 ⁹ Ω · cm or more, and a dielectric constant of less than 3 can be used.

In order to obtain the liquid developer of the present invention, the colorant, the binder resin, the charge control agent and other charge enhancers, if necessary, are added to the electrically insulating single solution so that they have a predetermined concentration. Can be obtained by dispersing so that
For example, it is preferable to prepare a concentrated toner by uniformly kneading them with a ball mill, a sand mill, an attritor or the like to prepare a concentrated toner, and further dilute it with an electrically insulating carrier liquid to prepare a developer.

In order to develop an electrostatic charge using the liquid developer of the present invention, an electrostatic charge image is formed on a photosensitive substrate comprising a conventionally known organic photoconductor or inorganic photoconductor, and then the present invention is applied. An image corresponding to the electrostatic latent image can be obtained by bringing the liquid developer into contact with the developer and removing the excess developer. Further, the toner image thus obtained is printed on paper,
Alternatively, via a recording medium such as a plastic film,
By performing uniform charging with a polarity opposite to that of the toner, it is possible to electrostatically transfer to various recording media. Examples of the organic photoconductor include well-known organic photoconductors, for example, a poly-N-vinylcarbazole-based electrophotographic photosensitive substrate, an electrophotographic photosensitive substrate containing an organic pigment as a main component, a dye and a resin. An electrophotographic photosensitive substrate mainly composed of a eutectic complex is used. Examples of the inorganic photoconductor include zinc oxide, zinc sulfide, cadmium sulfide, selenium, a selenium-tellurium-arsenic alloy, and an amorphous silicon-based material.

Further, the liquid developer of the present invention can be prepared by using means other than the photoreceptor, for example, electrostatic recording paper, recording paper for ion flow, The present invention can also be applied when developing an electrostatic latent image formed on a dielectric such as a film. The development in this case can be performed in the same manner as in the case of the photoreceptor. Further, in order to transfer the obtained image to paper or a plastic sheet, the electrostatic method is used in the same manner as in the case of the photoreceptor. Can be implemented. Alternatively, when the dielectric material on which the electrostatic latent image is formed is a dielectric material having releasability, the developed image can be thermally transferred via the transfer medium by heating.

[0024]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention includes the following embodiments. (1) In a liquid developer for electrostatic charge development in which toner particles containing a colorant and a binder resin as main components are dispersed in a carrier liquid having a high insulating property and a low dielectric constant, a pigment of a chemical formula 1

Embedded image A yellow liquid developer for electrostatic charge development, comprising a pigment represented by the formula:

(2) The colorant is obtained by melt-kneading a pigment and a resin, and contains a pigment represented by the chemical formula 1 as the pigment, and the resin used at the time of melt-kneading is insoluble in the carrier liquid. The yellow liquid developer for electrostatic charge development according to (1).

As the binder resin, an amphiphilic resin, which is a resin having both a part soluble in the dispersion medium and a part insoluble in one molecule, is preferable. The specific examples of the present invention will be described, but the present invention is not limited to the following specific examples unless it exceeds the gist. In the specific examples, “parts” and “%” represent “parts by mass” and “% by mass”, respectively.

Examples of Synthesis of Binder Resin Amphiphilic non-aqueous dispersion resin A 80 parts of lauryl methacrylate, 10 parts of 2-hydroxyethyl methacrylate, 10 parts of N-vinylpyrrolidone, 1 part of di-tert-butyl peroxide and 1 part of 148 parts of Isopar G
The reaction solution was charged into a reaction vessel equipped with a nitrogen gas introduction pipe, a stirrer, and a cooling pipe, heated to 130 ° C., and reacted at 130 ° C. for 6 hours to obtain a first polymer solution. Next, the temperature was lowered to 80 ° C., 1.5 parts of isophorone diisocyanate, 0.03 part of di-n-butyltin dilaurate and 2 parts of “Isoper G” were added, and a urethanization reaction was carried out at 80 ° C. for 2 hours, followed by cooling. , Non-volatile content
A 38.2% solution of the crosslinked polymer was obtained. The crosslinked polymer 131
Were charged into the same reaction vessel as above, and then 152 parts of "Isopar G" and 2-hydroxypropyl methacrylate 5 parts were added.
Parts, 40 parts of methyl methacrylate, 5 parts of β-methacryloxyethyl phthalate and 0.25 part of azobisisobutyronitrile, and then heated to 80 ° C. and reacted at 80 ° C. for 6 hours to obtain a nonvolatile matter of 30%. % Of a white fixing agent dispersion. The non-aqueous dispersion resin thus obtained was referred to as “non-aqueous dispersion resin B”.

Amphiphilic non-aqueous dispersion resin B 93.3 parts of lauryl methacrylate, 3.7 parts of hydroxypropyl methacrylate, 3.0 parts of "acrylester PA" (monomer manufactured by Mitsubishi Rayon Co., Ltd.), and "perbutyl O" (polymerization catalyst manufactured by NOF Corporation) ) 2.5 parts and “Perbutyl Z” (polymerization catalyst manufactured by NOF Corporation) 1.5 parts “Isopar G” (aliphatic hydrocarbon solvent manufactured by Exxon Chemical Co.) 100 parts
The mixture was charged into a reaction vessel equipped with a stirrer and a cooling tube, heated to 120 ° C., and reacted at 120 ° C. for 8 hours to obtain a polymer having a nonvolatile content of 48.8%. Next, the temperature was lowered to 70 ° C., 5.7 parts of isophorone diisocyanate, 0.05 parts by weight of dibutyltin dilaurate and 5.7 parts of “Isoper G” were added, and a urethanization reaction was carried out at 70 ° C. for 4 hours. % Intermediate solution was obtained. 80 parts of the above solution of the intermediate was charged into the same reaction vessel as above, and further, “Isoper G” 105
Parts, 2.7 parts of hydroxypropyl methacrylate, 28.7 parts of methyl methacrylate, 28.6 parts of 2-ethylhexyl methacrylate, 0.3 parts of perbutyl D (polymerization catalyst manufactured by NOF Corporation) and 0.3 parts of perbutyl Z (polymerization catalyst manufactured by NOF Corporation), and 110 After reacting at 5 ° C. for 5 hours, 83 parts of Isopar G (aliphatic hydrocarbon solvent manufactured by Exxon Chemical Co., Ltd.) was added and cooled to obtain a graft polymer solution having a nonvolatile content of 28.5%. The non-aqueous dispersion resin thus obtained was referred to as “non-aqueous dispersion resin A”.

Next, preferred embodiments of the present invention will be described. As the coloring agent, the pigment represented by the chemical formula 1 can be directly mixed and kneaded with an amphiphilic non-aqueous dispersible resin using a ball mill or the like, and then used.

(Example 1) "Yellow 950" (Yellow pigment CI Pigment Yellow 97 manufactured by Arimoto Chemical Industry Co., Ltd.) 18 parts "Non-aqueous dispersion resin A" 90 parts "Zirconium naphthenate" 1.0 part "ISOPAR G" (Exxon Chemical Co., Ltd.) 125 parts of the above mixture was dispersed in a ball mill for 24 hours, and then diluted with "Isopar G" to a nonvolatile content of 12% to obtain a concentrated toner. The concentrated toner was stable without caking even after storage for 6 months. Further, a developer was obtained by diluting 100 parts of the above concentrated toner with 2,000 parts of “ISOPAR G”. Next, using a color electrostatic plotter “EP-4010” manufactured by Seiko Denshi Kogyo Co., Ltd., an electrostatic latent image was formed on electrostatic recording paper and developed with the above liquid developer. A yellow image was obtained. The color reproducibility of the secondary colors green and red was also good. (The commercially available magenta and cyan liquid developers were used.)

(Comparative Example 1) In Example 1, "Shimler Fast Yellow G" was used instead of "Yellow 950".
RF "(CIPigment Yell manufactured by Dainippon Ink and Chemicals, Inc.)
A concentrated toner and a developer were prepared in the same manner as in Example 1 except that ow13) was used. When the stability of the concentrated toner was checked in the same manner as in Example 1, soft caking was formed one month after standing, and it was found that Comparative Example "Shimler First Yellow GRF" had a problem in stability. .

Further, as a more preferred example, an embodiment in which a pigment and a resin are melt-kneaded will be described. The pigment and the resin having a solubility parameter of 8.5 or more can be melt-kneaded with a pressure kneader, and then further pulverized into a fine powder with a pulverizer. Unlike the binder resin, the resin is preferably a thermoplastic resin unnecessary for the carrier liquid. The mass ratio of the pigment and the resin is the sum of the two.
15 to 40 parts by weight of the pigment when 100 parts by weight, and the resin 8
It is desirable to use 5 to 60 parts by weight.

An outline of a method for preparing a liquid developer when a pigment and a resin are melt-kneaded is described below. Colorant 100 parts by mass Non-aqueous dispersion resin 50 to 100 parts by mass Charge control agent 1 to 10 parts by mass Carrier liquid (aliphatic hydrocarbon solvent with solubility parameter of 7.5 or less) 150 to 250 parts by mass

The above mixture is uniformly mixed and kneaded with a ball mill or the like, and this dispersion is diluted with a carrier liquid so as to have a concentration of 5 to 15% by mass to obtain a liquid concentrated toner. Further, at the time of actual use, the liquid concentrated toner is diluted about 15 to 30 times with a carrier liquid to obtain a liquid developer.

(Manufacture Example of Colorant) (Colorant 1) 25 parts by mass of Shimla First Yellow 4186 (CIPigment Yellow 97 manufactured by Dainippon Ink and Chemicals, Inc.) Epicoat 1004 (manufactured by Shell Sekiyu KK) 50 parts by mass Epicoat 1007 (Manufactured by Shell Petroleum Co., Ltd.) 25 parts by mass A mixture having the above composition is melt-kneaded using a pressure kneader, and the obtained colored mass is ground using a rotoplex, and a yellow colorant fine powder of 1 mm pass is used. I got The colorant thus obtained is referred to as Colorant 1.

(Example 2) "Colorant 1" 60 parts by mass "Non-aqueous dispersion resin B" 40 parts by mass "Zirconium naphthenate" 3 parts by mass "ISOPAR G" (aliphatic hydrocarbon solvent manufactured by Exxon Chemical Co., Ltd.) 142 Parts by mass The above mixture was uniformly mixed and dispersed by a ball mill to prepare a liquid concentrated toner. Further, the concentrated toner was diluted 20 times with Isopar G to obtain a developer. After allowing this developer to stand for 3 months, the sedimented toner was re-dispersed. As a result, there was almost no agglomerate and good re-dispersibility was exhibited. Further, when an electrostatic latent image was formed on electrostatic recording paper using an electrostatic plotter “EP-101” manufactured by Matsushita Electric Transmission Co., Ltd. and developed, a clear yellow image without image deletion was obtained.

(Comparative Example 2) In the colorant 1 of the production example of the colorant, instead of "Shimler Fast Yellow 4186", "Shimler First Yellow GFconc" (CIPigment Yellow 12 manufactured by Dainippon Ink and Chemicals, Inc.)
To obtain a colorant for comparison. Next, using this coloring agent, a concentrated toner and a developer were produced in the same manner as in Example 1. After allowing the developer to stand for three months, the sedimented toner was re-dispersed. As a result, aggregates were observed and the re-dispersibility was poor.

[0038]

According to the liquid developer of the present invention, chemical formula 1
When the pigment represented by the formula (1) is directly dispersed in a binder resin to prepare a concentrated toner, which is diluted and stored for a long time in the state of a developer, the pigment exhibits good redispersibility, and furthermore, the pigment represented by the formula (1) Melt-kneaded does not cause poor dispersion such as caking and shows excellent dispersion stability even when the dispersion concentration of the pigment is high.

Claims (2)

[Claims] 1. A liquid developer for electrostatic charge development in which toner particles containing a colorant and a binder resin as main components are dispersed in a carrier liquid having a high insulating property and a low dielectric constant. , Embedded image A yellow liquid developer for electrostatic charge development, comprising a pigment represented by the formula: 2. The colorant is obtained by melting and kneading a pigment and a resin, and the pigment has a chemical formula 1 The yellow liquid developer for electrostatic charge development according to claim 1, wherein the resin used in melt-kneading is insoluble in the carrier liquid.