JPH10254182A - Liquid developer for electrostatic latent image and image forming method - Google Patents

Abstract

(57) Abstract: An object of the present invention is to sufficiently print with a liquid developer black toner for an electrostatic latent image which is faithful to an original and can obtain good image reproducibility with high print density. It is an object of the present invention to provide a liquid developer for an electrostatic latent image capable of achieving a density. The present invention employs the following means in order to solve the above problems. That is, the liquid developer for an electrostatic latent image of the present invention is obtained by adding (a) a resin, (b) a colorant,
(C) A liquid developer for an electrostatic latent image obtained by dispersing a dispersant, wherein the colorant comprises carbon black and an azine dye. Provided is a liquid developer for an electrostatic latent image which can obtain high image density and high image reproducibility with respect to a document. An electrically insulating aliphatic hydrocarbon solvent includes:
(A) A liquid developer for an electrostatic latent image obtained by dispersing a resin, (b) a colorant, and (c) a dispersant, wherein the colorant comprises carbon black and an azine dye. Liquid developer for images.

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.

[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 comprising a natural or synthetic resin as a binder, a pigment or a dye as a colorant, and a dispersant such as a metal soap as an additive are each mixed with a carrier liquid and uniformly mixed. 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%. The one proposed in, for example, Japanese Patent Application Laid-Open No. 89971/1989 has been used.

[0003]

When such a liquid developer is used as a developer in an ion flow recording method,
Organic pigments such as yellow, magenta, and cyan can provide a sufficient print density, while black can provide a sufficient density.
The use of carbon black MA-100 or spirit black PAB described in Japanese Patent Application Laid-Open No. 2-89971 has a problem that a sufficient print density cannot be obtained.

[0004] In view of the problems of the prior art, the present invention has
An object of the present invention is to provide a liquid developer for an electrostatic latent image which is faithful to a document and which can obtain good image reproducibility with high print density.

[0005]

The present invention employs the following means in order to solve the above problems. That is, the liquid developer for an electrostatic latent image of the present invention is obtained by adding (a) a resin, (b) a colorant,
(C) A liquid developer for an electrostatic latent image obtained by dispersing a dispersant, wherein the colorant comprises carbon black and an azine dye.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention is faithful to a manuscript,
In addition, we have conducted intensive studies on liquid developers for electrostatic latent images that can provide good image reproducibility with high print density, and by using a combination of specific colorants, these problems can be solved at once. It is what we have determined to do.

In the present invention, an electrically insulating aliphatic hydrocarbon solvent is used as a dispersion medium of a resin, a colorant and a dispersant, or as a carrier liquid.

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, 2028 sold by Idemitsu Oil Co., Ltd., and NAS-3, NAS-4 sold by NOF Corporation. 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 of 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 such a resin, 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.

[0010] As the soluble copolymer segment, one or more selected from alkyl acrylate and alkyl methacrylate and one selected from cycloalkyl acrylate, cycloalkyl methacrylate, aralkyl acrylate and aralkyl methacrylate are used. A copolymer segment having the above as a main component is preferably used, and among them, at least one selected from alkyl acrylate and alkyl methacrylate and at least one selected from cycloalkyl acrylate and cycloalkyl methacrylate The main component is a copolymer segment. The soluble copolymer segment may be copolymerized with other vinyl compounds such as vinyl versatate. Usually, the copolymerization ratio can be varied depending on the purpose, but if the range generally used is strongly specified, one selected from alkyl acrylate and alkyl methacrylate is 40 to 80% by weight, preferably 45 to 7% by weight.
5 wt%, one selected from cycloalkyl acrylate, cycloalkyl methacrylate, aralkyl acrylate and aralkyl methacrylate is 20 to 60 wt%, preferably 25 to 50 wt%, and the vinyl compound is 0 to 20 wt%, preferably 5 to 20 wt%. A range of ~ 15 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 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 modifier 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 characterized by employing a combination of carbon black and an azine dye. In cases other than such combinations, for example, when using only carbon black or using only an azine-based dye, problems such as low print density occur.

Here, furnace black, acetylene black, channel black and the like can be used as carbon black.
In particular, it is preferable to use furnace black. Among these carbon blacks, the specific surface area is 100 m ^2.
/ G or more is preferably used from the viewpoint of coloring power. Such a specific surface area can be determined by measuring according to the BET method according to ASTM D3037-73.

Specific examples of carbon black include Raven 1500 and 125 manufactured by Colombian Carbon.
5, 1170, 3500, MA7, MA manufactured by Mitsubishi Chemical Corporation
77, MA8, MA11, MA00, MA600, Mogul L, MONARCH100 manufactured by Cabot Corporation
0, 800, REGAL660, etc. can be used.

Specific examples of the azine dyes include Bontron N-01, 02, 03, 04 and Orient Chemical Co., Ltd.
09, 10, 11, 13 etc. can be used.

It is preferable that the addition ratio of the carbon black to the azine dye is 1: 3 or more and 2: 1 or less. More preferably, it is 1: 2 or more and 3: 2 or less.

If the ratio of the carbon black to the azine dye is less than 1: 3, there may be a problem in the weather resistance of the colorant. In some cases, the print density is not sufficient and the print density is low.

The ratio of the solid content of the colorant obtained by combining the carbon black and the azine dye to the solid content of the developer is from 25% by weight to 80% by weight, and more preferably 30% by weight.
It is preferably at least 70% by weight. When the solid content is less than 25% by weight, the print density becomes insufficient, and when it exceeds 80% by weight, the fixability becomes poor.

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

[0028]

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 obtained 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 Resin obtained in Reference Example 1 100 parts MOGUL L (manufactured by Cabrack) 20 parts (specific surface area: 138 m ² / g) Bontron N-01 (manufactured by Orient Chemical) 30 parts Aluminum oxide stearate 10 Part (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.) Attritor After further kneading for 5 hours, 550 parts of "Isopar" G was further added and kneaded for 2 hours to obtain a concentrated toner. 40 parts of this concentrated toner was taken and 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 with a print density of 1.23 without roughness was obtained. Even when printing was continued for 200 sheets with this developer, an image having good reproducibility was obtained as in the initial stage.

The measurement of print density was carried out using RD-91 manufactured by Macbeth.
8 was performed.

Example 2 Resin obtained in Reference Example 1 100 parts MA-100 (manufactured by Mitsubishi Chemical Corporation) 20 parts (specific surface area: 134 m ² / g) Bontron N-10 (manufactured by Orient Chemical) 30 parts Aluminum oxide stearate 10 parts (“Olive” AOS, manufactured by Hope Pharmaceutical Co., Ltd.) Methyl oleate 6 parts (Unistar M-182A, manufactured by NOF Corporation) 150 parts of “ISOPAR” G (manufactured by Esso Chemical Co., Ltd.) After obtaining a developer in the same manner as in Example 1, printing was performed, and a good image having a print density of 1.15 was obtained. Also, as a result of printing 200 sheets continuously,
An image with good reproducibility was obtained when the print density was within 0.2.

Comparative Example 1 Resin obtained in Reference Example 1 100 parts MA-100 (manufactured by Mitsubishi Chemical Corporation) 50 parts Aluminum oxide stearate 10 parts (“Olive” AOS manufactured by Hope Pharmaceutical Co., Ltd.) Methyl oleate 6 parts ( 150 parts of Isopar G (manufactured by Nippon Oil & Fats Co., Ltd.) (manufactured by Esso Chemical Co., Ltd.) A developer was obtained from this composition in the same manner as in Example 1, and printing was performed. A sufficient print density of 0.8 was not obtained.

Comparative Example 2 Resin obtained in Reference Example 1 100 parts Bontron N-01 (manufactured by Orient Chemical) 50 parts Aluminum oxide stearate 10 parts (“Olive” AOS manufactured by Hope Pharmaceutical Co., Ltd.) Methyl oleate 6 parts ( 150 parts of Isopar G (manufactured by Nippon Oil & Fats Co., Ltd.) (manufactured by Esso Chemical Co., Ltd.) A developer was obtained from this composition in the same manner as in Example 1, and printing was performed. A sufficient print density of 0.7 was not obtained.

[0036]

According to the present invention, it is possible to provide a liquid developer for an electrostatic latent image capable of achieving high image density and good image reproducibility. The liquid developer for an electrostatic latent image of the present invention forms an ion pattern on a recording medium using an ion printer which forms an ion image by an ion flow, and develops information according to the ion pattern formed image to record information, It is effectively used as a developer in an ion flow recording method for obtaining a recording medium.

Claims (4)

[Claims] 1. An electrically insulating aliphatic hydrocarbon solvent,
(A) a liquid developer for an electrostatic latent image obtained by dispersing a resin, (b) a colorant, and (c) a dispersant, wherein the colorant comprises carbon black and an azine dye. Liquid developer for latent images. 2. The resin according to claim 1, wherein the resin comprises 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. A non-gel copolymer that is a component, and is composed of 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 is insoluble in the solvent as a whole. The liquid developer for an electrostatic latent image according to claim 1, wherein 3. The static color according to claim 1, wherein the colorant is a mixture of the carbon black and the azine-based dye in an addition ratio of 1: 3 or more and 2: 1 or less. Liquid developer for electrostatic latent images. 4. An image for forming an image by developing an ion image pattern formed on a recording medium by an ion current using the liquid developer for an electrostatic latent image according to claim 1. Forming method.