JPH1083100A - Liquid developer for electrostatic latent image and image forming method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a liq. developer having satisfactory color matchability with an original in full-color printing by using a disazo yellow pigment, a monoazo lake, and a copper phthalocyanine pigment as yellow, magenta, and cyan colorants, respectively. SOLUTION: When a resin, colorants and a dispersant are dispersed in an electric insulating aliphatic hydrocarbon solvent to obtain a liq. developer for an electrostatic latent image, a disazo yellow pigment, a monoazo lake and a copper phthalocyanine pigment are used as yellow, magenta and cyan colorants, respectively. The hydrocarbon solvent is used as a dispersive medium or a carrier liq. The total solid content of the pigments is 25-80wt.%, preferably 30-70wt.% of the total solid content of the developer. The resultant liq. developer ensures satisfactory color reproducibility to an original.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a liquid developer used for developing an electrostatic latent image formed by an electrophotographic system or an electrostatic recording system. In particular, a developer of a full-color ion flow recording method for forming an ion pattern on a recording medium using an ion printer that forms an ion image by an ion flow, and developing according to the ion pattern-formed image to obtain an information recording and an image recording medium. Effectively used as

[0002]

2. Description of the Related Art A general liquid developer contains a binder, a coloring agent, an additive and the like in an electrically insulating carrier liquid having a high electric resistance and a low dielectric constant, such as an aliphatic hydrocarbon solvent. It is a dispersion of the toner particles, which is usually a natural or synthetic resin as a binder, a pigment or dye as a colorant, a dispersant such as metal soap as an additive, respectively mixed with the carrier liquid, uniformly The concentrated toner having a non-volatile content of about 1 to 20 wt% is prepared by kneading, and then the concentrated toner is prepared by diluting the concentrated toner to have a non-volatile content of about 0.1 to 5 wt%. -89971 and the like.

When full-color printing is performed using such a liquid developer as a developer in a full-color ion flow recording method, a problem such as matching with the color of an original has occurred.

The reasons why the color of the original cannot be reproduced are as follows: (1) Difference in colorant (2) Difference in print density depending on color (3) Difference in secondary color development due to overlapping of colors It was presumed that the combination between colors would be important for the color development.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned drawbacks of the prior art, and has as its object to obtain a liquid developer having good matching with the color of an original in full-color printing. It is in.

[0006]

In order to solve the above-mentioned problems, the present invention has the following arrangement.

[0007] The electrically insulating aliphatic hydrocarbon solvent,
In a liquid developer for an electrostatic latent image obtained by dispersing (a) a resin, (b) a colorant, and (c) a dispersant, disazo yellow is used as yellow, monoazo lake is used as magenta, and copper phthalocyanine pigment is used as cyan. A liquid developer for an electrostatic latent image.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, an electrically insulating aliphatic hydrocarbon solvent is used as a dispersion medium or a carrier liquid for a resin, a colorant and a dispersant.

The electrically insulating aliphatic hydrocarbon solvent is not particularly limited, but usually has an electric resistance of 10 or less.
It has a dielectric constant of not more than 9 Ω · cm and not more than 3, and has a boiling point of 6
Commercially available, such as n-hexane, n-heptane, n-octane, n-nonane, n-decane, n-undecane, n-dodecane, n-tridecane, isooctane, ligroin and mixtures thereof in the range of 8 to 250 ° C. "ISOPAR" sold by Esso Oil Co., Ltd.
E, G, H, L, M, “Solvesso” 150, “Shellsol” 71 sold by Shell Sekiyu KK,
Organic solvents such as "IP Solvent" 1016, 1620, and 2028 sold by Idemitsu Oil Co., Ltd., and NAS-3 and NAS-4 sold by NOF Corporation are listed as examples. Particularly, the boiling point is 150 to 25.
Solvents at 0 ° C., such as “Isopar” G, H, L, are preferred.

The resin used in the liquid developer of the present invention includes an ethylene copolymer, an acrylic copolymer, an ethylene-vinyl acetate copolymer, an ethylene-acrylate copolymer, and a metal such as ethylene and methacrylic acid. Ion-crosslinked polymers, ethylene-vinyl chloride copolymers, ethylene-maleic anhydride copolymers, ethylene-vinyl acetate-acrylate terpolymers, vinyl acetate-acrylic copolymers, vinyl acetate-methacrylic copolymers, etc. Preferably, the resin is at least one resin selected from alkyl acrylate and alkyl methacrylate and one or more resin selected from cycloalkyl acrylate, cycloalkyl methacrylate, aralkyl acrylate and aralkyl methacrylate.
A non-gel non-gel insoluble in the solvent as a whole, comprising a copolymer segment soluble in an aliphatic hydrocarbon solvent having a main component of at least one kind and a polymer segment insoluble in the solvent having vinyl acetate as a main component. Copolymer.

By using the resin as described above, it is possible to obtain a developer in which the charging characteristics of the colored particles in a solvent, the dispersibility, and the fixing property to paper are well balanced. As the soluble copolymer segment, one or more selected from alkyl acrylate and alkyl methacrylate and one or more selected from cycloalkyl acrylate, cycloalkyl methacrylate, aralkyl acrylate and aralkyl methacrylate are mainly used. Copolymer segments as constituent components are preferably used, and among them, one selected from alkyl acrylates and alkyl methacrylates is particularly preferred.
A copolymer segment containing at least one kind and at least one kind selected from cycloalkyl acrylate and cycloalkyl methacrylate as a main component is preferable. The soluble copolymer segment may be copolymerized with other vinyl compounds such as vinyl versatate. Usually, the copolymerization ratio of these can be changed according to the purpose. However, if the range generally used is specified, one selected from alkyl acrylate and alkyl methacrylate is 40 to 80 wt%, preferably 45 to 75 wt%, and acrylic 20 to 60% by weight, preferably 25 to 50% by weight, of one selected from cycloalkyl acrylate, cycloalkyl methacrylate, aralkyl acrylate and aralkyl methacrylate
%, The vinyl compound content is 0 to 20% by weight, preferably 5 to 15%.
A range of wt% is used.

The alkyl group of the alkyl acrylate or alkyl methacrylate used as the soluble copolymer segment is not particularly limited, but is usually an alkyl group having 3 to 20 carbon atoms, preferably an alkyl group having 4 to 18 carbon atoms. Those having a group are preferably used. Specific examples include butyl or isobutyl acrylate, methacrylate, t-butyl, 2-ethylhexyl, octyl,
Esters such as isononyl, decyl, lauryl, dodecyl and stearyl are used. The cycloalkyl group of the cycloalkyl acrylate or cycloalkyl methacrylate in the present invention is not particularly limited, but usually has 6 to 8 carbon atoms, and preferably includes a cyclohexyl group. As a specific example, cyclohexyl acrylate or cyclohexyl methacrylate is most preferably used. As aralkyl acrylate or aralkyl methacrylate, benzyl acrylate or benzyl methacrylate is most preferably used.

It is more preferable to use an organic mercaptan as a polymerization regulator during the polymerization of the soluble copolymer segment, since the dispersion stability of the insoluble polymer segment is improved. As the organic mercaptan, higher alkyl mercaptans generally used as polymerization regulators are used, and there is no particular limitation. Usually, higher alkyl mercaptans having an alkyl group having 7 or more carbon atoms, preferably 8 to 20 carbon atoms, are used. Used. Particularly, n-octyl mercaptan, n-dodecyl mercaptan, t-dodecyl mercaptan, n-octadecyl mercaptan and the like are preferably used. The polymerization catalyst for the soluble copolymer segment is not particularly limited, but usually an azobisalkylnitrile having 3 to 6 carbon atoms in the alkyl group is used. In particular, azobisisobutyronitrile is preferred.

As the insoluble copolymer segment, a copolymer segment containing vinyl acetate as a main component is preferably used, and alkyl acrylate, alkyl methacrylate, cycloalkyl acrylate, cycloalkyl methacrylate, aralkyl acrylate are preferred. And a copolymer segment with one or more kinds of aralkyl methacrylate and the like. As a polymer segment having vinyl acetate as a main component, a vinyl acetate component is 50 to 100 wt%,
Preferably, a polymer segment or a copolymer segment of 65 to 100% by weight is preferably used. The alkyl acrylate or alkyl methacrylate here is not particularly limited, but the alkyl group usually has 1 carbon atom.
-20, preferably 1-18 alkyl groups, specifically methyl acrylate or methyl methacrylate, ethyl, 2-hydroxyethyl, isobutyl,
Esters such as octyl, stearyl and isononyl are preferably used. The cycloalkyl group of the cycloalkyl acrylate or the cycloalkyl methacrylate herein is not particularly limited, but usually has 6 carbon atoms.
To 8, preferably a cyclohexyl group. As a specific example, cyclohexyl acrylate or cyclohexyl methacrylate is most preferably used. As aralkyl acrylate or aralkyl methacrylate, benzyl acrylate or benzyl methacrylate is most preferably used.

As the polymerization catalyst used for producing the insoluble polymer segment, diacyl peroxides can be usually used, but benzoyl peroxide, lauroyl peroxide, p-chlorobenzoyl peroxide and the like are preferably used. Can be

As a method for producing a copolymer as a resin used in the liquid developer of the present invention, for example, the above-mentioned aliphatic hydrocarbon solvent can be used as a reaction solvent. A monomer for composing the copolymer segment is added, polymerization is performed to obtain a soluble copolymer segment, and then a monomer for composing the insoluble polymer segment is added as it is, followed by polymerization. It can also be obtained by a step method. The molecular weight of the copolymer varies depending on the type of the monomer used and the combination thereof, but is 5,000 to 50,000 in terms of weight average molecular weight.
0, preferably from 8,000 to 20,000
It is particularly preferred to prepare Although the ratio of the soluble copolymer segment to the insoluble polymer segment varies depending on the combination of the monomers used, generally, the soluble copolymer segment comprises 25 to 60% by weight of the whole copolymer, particularly 30 to 45% by weight. It is preferably in the range of weight percent.
In this range, the particle size of the insoluble polymer segment is presumed to be small, and the colorant and the soluble copolymer segment are sufficiently bonded. Incidentally, the copolymer is preferably a graft copolymer consisting of the soluble copolymer segment and the insoluble polymer segment, but is not necessarily limited to this, as long as the copolymer has both segments. Not necessarily.

The colorant used in the present invention is a combination of disazo yellow as yellow, monoazo lake as magenta, and copper phthalocyanine pigment as cyan. More preferably, disazo yellow AAA (C.I.
I. Pigment Yellow 12), Brilliant Carmine 6B (CI Pigment Red 5)
7: 1), phthalocyanine blue (CI Pigm)
ent Blue 15: 3).

When a pigment other than this combination is used, the hue of red, which is the superimposed color of yellow and magenta, green, which is the superimposed color of yellow and cyan, and blue, which is the superimposed color of magenta and cyan, are lower than those of the original. Problems such as differences occur.

The ratio of the solid content of the pigment in the solid content of the developer is preferably 25% by weight or more and 80% by weight or less, more preferably 30% by weight or more and 70% by weight or less. When the solid content is less than 25% by weight, the print density becomes insufficient,
If it exceeds 0% by weight, the fixability becomes poor.

In order to improve the charging characteristics of the developer, the specific conductivity of the pigment is set to 100 μs / yellow for yellow.
cm or less, magenta is preferably 500 μs / cm or less, and cyan is preferably 200 μs / cm or less. If the upper limit is exceeded, problems such as white background stains occur. As a method for measuring the specific conductivity of the pigment, 5 g of a dried sample of the pigment was weighed into a 300 ml beaker, and 1 ml of ethanol was added to wet well, and then ion-exchanged water (specific conductivity 5 μs / cm or less, PH7. 0 ± 1.0) 2
Add 00ml and mix well. Next, the mixture is boiled for 5 minutes, and the boiled ion-exchanged water is cooled with water until it reaches room temperature.
Wash to a ml flask, add ion-exchanged water to the marked line, and mix well. Next, filtration is performed using filter paper (Toyo Filter Paper No. 5C). The first about 30 ml of the filtrate is discarded, the remainder is placed in a beaker and the resulting 25 ml is measured using a conductivity meter.

Specific examples of the yellow pigment include Seika Fast Yellow 23, which is a disazo yellow pigment.
00, H7055, 2340TN, G2300, 230
0M (manufactured by Dainichi Seika), Fines Yellow G20S-1
2E, Lionol Yellow GR, GRO, No120
6 Lionol Yellow (manufactured by Toyo Ink), Shimura First Yellow GF, KET Yellow 406 (manufactured by Dainippon Ink) and the like.

Specific examples of the magenta pigment include a monoazo lake pigment, Seika Fast Carmine 6B7
0-1 (F), 6B1476T-7, 6B1478,6
B1480, 6B1483LT, 6B1488, 6B7
0M (manufactured by Dainichi Seika), Brilliant Carmine 6BA, Lionol Red 6BFG4215, 6BFG4200
(Made by Toyo Ink), Shimura First Carmin 6B, Ket Red 306, 307 (made by Dainippon Ink) and the like.

Specific examples of cyan pigments include chromofine blue 4920, which is a copper phthalocyanine pigment.
4927, 4920G, KBN, 4930, 4933
M, 4935, 4938 (manufactured by Dainichi Seika), 700
-10 cyanine blue, lionol blue FG-735
0 (manufactured by Toyo Ink), Fastgen Blue TGR Ket Blue 104 (manufactured by Dainippon Ink) and the like.

There is no particular limitation on black, and ordinary pigments can be used. Specific examples of the black colorant include carbon black, spirit black, aniline black (CIPigment Black 1), and fired metal pigments. As carbon black, any of furnace black, acetylene black, channel black and the like can be used.

The dispersant used in the present invention may be any as long as it can improve the dispersion stability and storability of the toner. For example, naphthenic acid, octylic acid, stearic acid, alkyl acid, alkylbenzene sulfonic acid, resin acid And metal salts of fatty acids are preferably used. Examples of the metal constituting the metal salt include Li, Ca, Ba, Zr, Mn, Co, and N.
Metals such as i, Cu, Zn, Cd, Al, and Pt and transition metals are effective. Particularly, a multimer, preferably a trimer of aluminum oxide acylate is also preferably used.
Multimers of aluminum oxide acylate include, for example, “Olive” AOS (manufactured by Hope Pharmaceutical Co., Ltd.), “Olive” AOO (manufactured by Hope Pharmaceutical Co., Ltd.), lubricant OA-S
(Kawaken Fine Chemical Co., Ltd.), lubricant OA-O
(Kawaken Fine Chemical Co., Ltd.) is particularly preferably used.

In the present invention, a charge control agent, a higher aliphatic polyester or the like may be added.

The liquid developer according to the present invention can be produced by various known methods of mixing and dispersing a liquid. For example, a mixture of a dispersion of a copolymer and a colorant, a mixture of a dispersant and the above compound is uniformly kneaded in an aliphatic hydrocarbon-based solvent by a ball mill, a sand mill, an attritor, or the like. It can be prepared by preparing a concentrated toner having a non-volatile content of the order, and diluting the concentrated toner with the aliphatic hydrocarbon solvent so that the non-volatile content becomes about 0.05 to 5 wt%.

The liquid developer of the present invention can develop an electrostatic latent image obtained by an electrophotographic method or an electrostatic recording method, and is effectively used as such a developer.

The present invention relates to a full color ion for forming an ion pattern on a recording medium by using an ion printer for forming an ion image by an ion flow, and developing according to the ion pattern formed image to obtain an information recording and an image recording medium. It is effectively used as a developer for flow recording.

[0030]

Examples of the present invention will be described below. Hereinafter, the number of parts means parts by weight.

Reference Example 1 Aliphatic solvent "Isopar" H (Exxon Chemical Co., Ltd.)
A mixture of 140 parts of 2-ethylhexyl methacrylate, 60 parts of benzyl methacrylate, 4 parts of dodecyl mercaptan, and 2 parts of azobisisobutyronitrile was stirred for 1 hour while 490 parts of the mixture were heated and stirred at 90 ° C. After that, a polymerization reaction was carried out while heating and stirring at 90 ° C. for 1 hour. Next, 250 parts of vinyl acetate and methacrylic acid 2-
35 parts of ethylhexyl, 15 parts of benzyl methacrylate,
A mixture of 1 part of benzoyl peroxide was added dropwise over 3 hours, and the mixture was kept at 90 ° C. to advance the polymerization reaction. After the addition, 0.1 part of azobisisobutyronitrile was added three times every hour, and the polymerization was terminated.

The resulting solution was a white emulsion having extremely excellent dispersion stability. The nonvolatile content of this emulsion was 50% by weight. In the above production example, the soluble copolymer segment was a copolymer segment of 140 parts of 2-ethylhexyl methacrylate and 60 parts of benzyl methacrylate, and the insoluble polymer segment was 250 parts of vinyl acetate and 2 parts of methacrylic acid. -Ethylhexyl 3
It is a copolymer segment of 5 parts and benzyl methacrylate.

Example 1 (1) Cyan developer 100 parts of the resin obtained in Reference Example 1 700-10 Cyanine blue (copper phthalocyanine pigment) 50 parts (manufactured by Toyo Ink Manufacturing Co., Ltd.) Specific conductivity: 95 μs / cm Pigment concentration in solids 43% Aluminum oxide stearate 10 parts (manufactured by Hope Pharmaceutical Co., Ltd.) Olive "AOS" Methyl oleate 6 parts (Nippon Oil & Fats Co., Ltd. Unistar M-182A) "ISOPAR" G 150 parts (Esso Chemical Co., Ltd.) (2) Magenta developer 100 parts of resin obtained in Reference Example 1 Lionol Red 6B FG-4213 (monoazo lake pigment) 50 parts (Toyo Ink Mfg. Co., Ltd.) Specific conductivity: 255 μs / cm Pigment concentration in solids 43% Aluminum oxide stearate 5 parts (Hope Pharmaceutical Co., Ltd.) "Olive" AOS) Methyl oleate 3 parts (Unistar M-182A manufactured by NOF Corporation) 150 parts of Isopar G (manufactured by Esso Chemical Co., Ltd.) (3) Yellow developer 100 parts of resin obtained in Reference Example 1 Fines Yellow G20S-12E (disazo yellow pigment) 50 parts (manufactured by Toyo Ink Mfg. Co., Ltd.) Specific conductivity: 34 μs / cm Pigment concentration in solid content 43% Aluminum oxide stearate 10 parts (Hope Pharmaceutical Co., Ltd. “Olive” AOS) Methyl oleate 6 parts (Nippon Oil & Fat Co., Ltd. Unistar M-182A) After kneading 150 parts of "ISOPAR" G (manufactured by Esso Chemical Co., Ltd.) for 5 hours with an attritor, further adding 550 parts of "ISOPAR" G and kneading for 2 hours to obtain a concentrated toner. It was diluted with 960 parts of "ISOPAR" G to obtain a developer. When an electrostatic recording paper having a latent image obtained by the electrostatic recording method was developed using this developer, a clear image without roughness was obtained. 20 with this developer
A clear image with good reproducibility without roughness was obtained even when printing 0 sheets was continued.

Further, the original is yellow, magenta,
When the color difference of the primary color of cyan is suppressed within ΔE <1,
Good reproducibility was exhibited when the color difference ΔE of the secondary color was 2.3.

Here, the color difference was measured using a color difference meter CR-121 manufactured by Minolta.

Example 2 A full-color developer was prepared by using the following pigment in place of the pigment of Example 1.

Yellow: Seika First Yellow 23
00 (disazo yellow pigment, manufactured by Dainichi Seika) Magenta: Seika Fast Carmine 6B1480 (monoazo lake pigment, manufactured by Dainichi Seika) Cyan: Chromofine Blue 4920 (manufactured by Dainichi Seika,
(Copper phthalocyanine pigment) When printing was performed in the same manner as in Example 1 using this full-color developer, the secondary color difference ΔE was 1.8, indicating good reproducibility.

Comparative Example 1 As a result of printing using Oriental Yellow G (Fast Yellow Pigment, manufactured by Toyo Ink Mfg. Co., Ltd.) as yellow instead of the pigment of Example 1, red which is a secondary color of yellow and magenta was obtained. In the portion, ΔE = 4.1, which caused a visual difference, and the reproducibility was insufficient.

Comparative Example 2 As a result of printing using Ultra Rose RN (Rhodamine 6G lake pigment, manufactured by Toyo Ink Mfg. Co., Ltd.) as magenta instead of the pigment of Example 1, the result is a secondary color of cyan and magenta. ΔE = 5.6 was shown in the blue part, a difference was visually observed, and the reproducibility was insufficient.

Comparative Example 3 As a result of printing using Rionogen Blue R (manufactured by Toyo Ink Mfg. Co., Ltd., Industron Blue pigment) instead of the pigment of Example 1 as cyan, secondary colors of cyan and yellow were obtained. ΔE = 3.7 in a certain green area, which caused a visual difference, resulting in insufficient reproducibility.

[0041]

As described above, by using the liquid developer of the present invention, it is possible to provide a liquid developer for an electrostatic latent image capable of obtaining good color reproducibility on a document.

Claims (5)

[Claims] 1. An electrically insulating aliphatic hydrocarbon solvent,
In a liquid developer for an electrostatic latent image obtained by dispersing (a) a resin, (b) a colorant, and (c) a dispersant, disazo yellow is used as yellow, monoazo lake is used as magenta, and copper phthalocyanine pigment is used as cyan. A liquid developer for an electrostatic latent image. 2. The resin is mainly composed of at least one selected from alkyl acrylate and alkyl methacrylate and at least one selected from cycloalkyl acrylate, cycloalkyl methacrylate and aralkyl acrylate or aralkyl methacrylate. Component, and a copolymer segment soluble in the aliphatic hydrocarbon solvent, and a polymer segment insoluble in the solvent containing vinyl acetate as a main component, and a non-gel copolymer insoluble in the solvent as a whole The liquid developer for an electrostatic latent image according to claim 1, wherein 3. The solid content of the pigment is 2% of the solid content of the liquid developer.
The liquid developer for an electrostatic latent image according to claim 1, wherein the amount is 5% by weight or more and 80% by weight or less. 4. The electrostatic latent image according to claim 1, which is used in a process of developing an ion image pattern formed on a recording medium by an ion flow with a liquid developer to form a full-color image. Liquid developer for images. 5. An electrically insulating aliphatic hydrocarbon solvent,
In a liquid developer for an electrostatic latent image obtained by dispersing (a) a resin, (b) a colorant, and (c) a dispersant, disazo yellow is used as yellow, monoazo lake is used as magenta, and copper phthalocyanine pigment is used as cyan. An image forming method, comprising developing an ion image pattern formed on a recording medium by an ion stream using the liquid developer for an electrostatic latent image thus formed to form a full-color image.