JP2684378B2 - Liquid developer for electrostatic image - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to liquid developers having improved transfer, dispersibility and image properties used for developing electrostatic latent images.

"Prior art" Generally, a liquid developer used for developing an electrostatic latent image is a colorant such as carbon black or various pigments and is adsorbed or coated on the colorant to adjust the charge of toner particles and to promote dispersion. Further, a coating agent for imparting fixability after development, a dispersant for dissolving or swelling in a carrier liquid to impart dispersion stability of toner particles, a charge controlling agent for adjusting the charge amount of toner particles, and a high electric resistance (10 ⁹ to 10 ⁹ 10 ¹⁵ Ω · cm).

As the coating agent, butadiene rubber, styrene-butadiene rubber, cyclized rubber, rubber such as natural rubber, styrene resin, vinyltoluene resin, acrylic resin, methacrylic resin, polyester resin, polycarbonates, polyacetic acid Examples thereof include synthetic resins such as vinyls and ethylene copolymers, rosin-based resins, hydrogenated rosin-based resins, alkyd resins including modified alkyds such as linseed oil-modified alkyds, and natural resins such as polyterpenes. Other known phenol resins include modified phenol resins such as phenol formalin resins, natural resin modified maleic acid resins, pentaerythritol phthalate, chroman-indene resins, ester gum resins, and vegetable oil polyamides. There is. Among them, an ethylene copolymer can be mentioned as one excellent for transfer.

Japanese Patent Laid-Open No. 61-180248 discloses an example in which ethylene / methacrylic acid copolymer is used as an ethylene copolymer. However, since these copolymers have a large internal cohesive force due to a carboxyl group, they are not described in the patents. Even if a plasticizing method in which L is used and heating is performed at a temperature equal to or higher than the softening point is used, the dispersion is insufficient and it is difficult to form fine particles. For this reason, there are problems that the dispersion stability is poor, the sedimentation of the toner particles is large, and the resolution is poor when the image is developed due to roughness of the image.
JP-A-62-209543 discloses an example of using a polar solvent as a method for dispersing these copolymers, but a liquid developer using an electrically insulating non-aqueous solvent as a carrier liquid has a charging property. Above all, it cannot be said that it is a preferable method. As it is, in JP-A-58-129438, there is described a method of producing toner particles by heating and dissolving an ethylene-based copolymer such as ethylene / acetic acid and a vinyl copolymer in a solvent, followed by cooling. This method has problems that it is separated from the colorant when the polymer is dissolved, and the size of the particles that precipitate during cooling is not uniform. As can be seen from these examples, the conventional ethylene copolymer has a problem of dispersibility. Almost no other resins have good transferability and excellent dispersibility and fixability.

"Problems to be Solved by the Present Invention" When an ethylene copolymer is used as a coating agent, the transfer efficiency is good but the dispersibility is difficult, so that the dispersion stability is poor and the sedimentation of the toner particles is short. However, there are problems such as the occurrence of the image and the poor reproducibility of the image quality due to lack of resolution.

The first object of the present invention is excellent in transferability and dispersibility,
An object of the present invention is to provide a liquid developer for electrostatic charge images having good fixability.

A second object of the present invention is to provide a liquid developer for an electrostatic charge image, which is excellent in image reproducibility and gives high resolution image quality.

A third object of the present invention is to provide a liquid developer for an electrostatic image that gives high printing durability when used as a toner for a lithographic printing plate.

"Means for Solving Problems" The inventors of the present invention have a carrier liquid containing at least one copolymer represented by the following general formula (I) as a constituent component for electrostatic image. Liquid developer.

In the formula, R ₁ represents a hydrogen atom or a methyl group. R ₂ is an unsubstituted or substituted alkyl group having 6 or more carbon atoms, a benzyl group, an aryl group having an alkyl group having 2 or more carbon atoms or a sulfonic acid group as a substituent, an alkyloxy group,
It represents an alkyloxycarbonyl group or a dialkylcarbonyl group.

x and y represent the number of moles, and x: y = 0.995 to 0.80: 0.005 to 0.
2 (As the substituent of the substituted alkyl group, an alkyl group having 1 to 12 carbon atoms, an alkyloxy group having 1 to 12 carbon atoms, an aryloxy group, an alkyloxycarbonyl group having 1 to 12 carbon atoms, an aryloxycarbonyl group , A dialkylcarbonyl group having 1 to 12 carbon atoms, a diarylcarbonyl group, an alkyl / arylcarbonyl group, a hydroxyl group, a carboxyl group, a cyano group, a nitro group, a sulfonic acid group, a cycloalkyl group, an aryl group, an aralkyl group, and a halogen group. Further, the substituent may be substituted with the above-mentioned substituent).

 Next, the present invention will be described in detail.

The ethylene copolymer of the present invention is substantially insoluble or swellable in a supporting liquid, and is used as a coating agent for a colorant to form toner particles and impart a fixing property.
When used as a toner for a lithographic printing plate, a colorant is not always necessary and can be used alone to form toner particles.

Conventionally, ethylene copolymers are mainly ethylene
Vinyl acetate copolymers, ethylene / methacrylic acid copolymers, ethylene / ethyl acrylate copolymers and the like have been used for liquid developers.

When these ethylene copolymers were used for transfer, they often showed good transferability, but when they were used as a developer due to poor dispersibility, there was a marked precipitation of toner particles, and when they were developed, they became fine particles. It was not possible to obtain an image in which graininess due to coarse particles was noticeable. When it is used for transfer, it is important that the transferability is excellent as a liquid developer.
The dispersibility is as important as that, and the dispersity controls the image properties such as the resolution of the liquid developer.

The present invention was made to improve the dispersibility by utilizing the excellent transferability of the ethylene copolymer.

In order to satisfy good dispersibility, a component having an affinity for the supporting liquid is necessary. In the ethylene copolymer, the present inventors have found that those represented by the general formula (I) such as alkyl (meth) acrylate as a copolymerization component for ethylene are effective for improving dispersibility, and It has been found that they exhibit excellent transferability and fixability at the same time.

Hereinafter, the ethylene copolymer represented by the general formula (I) of the present invention will be further described.

In the general formula (I), when R ₂ is an unsubstituted or substituted alkyl group having 6 or more carbon atoms, specific examples of the alkyl group are:
Examples thereof include n-propyl group, n-butyl group, n-amyl group, n-hexyl group, n-octyl group, decyl group, dodecyl group, myristyl group, cetyl group and stearyl group. The alkyl group preferably has 3 to 22 carbon atoms.

Moreover, the thing which has a sulfonic acid group as a substituent can also be mentioned as a preferable example.

The molecular weight of these copolymers measured by GPC is 10,000-
It is 1,000,000 (weight average), preferably 20,000 to 500,000. Melt flow rate is 0.3 to 800 according to JIS K-6730 method
[G / 10 min], preferably 0.5 to 500 [g / 10 min].

Next, specific examples of the compound represented by formula (I) of the present invention will be given.

These ethylene copolymers are produced by a process such as bulk, solution, suspension or emulsion. The method is a high pressure polymerization method using a free radical initiator, an intermediate pressure polymerization method using a transition metal compound, a transition metal halide and an alkylaluminum compound. Medium and low pressure polymerization method. As another method, there is a method in which an acid chloride reagent is allowed to act on the carboxy group of a commercially available ethylene / methacrylic acid copolymer to form an acid chloride, and an appropriate alcohol is allowed to act to esterify. In this case, a wide range of alcohols can be selected, the reaction is relatively easy, and there is an advantage that a device such as a high-pressure pot is unnecessary. Next, the synthesis method is shown by a specific example.

Synthesis Example (Synthesis of Specific Compound 2) Toluene 1 was placed in a four-necked two container equipped with a reflux condenser equipped with a water content quantitative receiver, a stirring blade, a thermometer, and an adder.
, Nyukuren N-699 (manufactured by Mitsui-Dyupon Poly Chemical Co.), ethylene-methacrylic acid copolymer (copolymerization ratio of ethylene: methacrylic acid, by weight ratio
89:11) 100 g was added and the mixture was heated to reflux under N ₂ atmosphere and 50 ml was distilled off. After cooling to 60 ° C., 15 g of thionyl chloride was gradually added, and 1 hour later, 45 g of dodecyl alcohol was added. The temperature was raised to 65 ° C. and the reaction was carried out for 20 hours. After the reaction,
The reaction solution was precipitated in methanol 3, filtered, and washed with methanol. After drying, the IR spectrum was measured, and it was confirmed that the Carboxyl reactor was completely esterified with dodecyl alcohol.

Specific examples 1, 3, 4, 8, and 9 of the present invention are Niuclen N-
699 (manufactured by Mitsui Deupon Polychemical), which is an ethylene / methacrylic acid copolymer (ethylene:
A methacrylic acid copolymerization ratio (0.964: 0.036 molar ratio) can be used as a starting material and can be synthesized in the same manner as in the synthesis example. In addition, specific examples 5, 6, 7 and 10 are the same as the synthetic examples using an ethylene / methacrylic acid copolymer (ethylene: methacrylic acid copolymerization ratio 0.95: 0.05 molar ratio), which is also sold as Nikurel N-925, as a starting material. Can be synthesized by the method. The structure of each copolymer was confirmed by IR spectrum.

In the present invention, the carrier liquid has an electric resistance of 1 × 10
A nonaqueous solvent having a resistivity of ⁹ Ω · cm or more and a dielectric constant of 3 or less can be used. Examples of the non-aqueous solvent include solvents such as linear or branched aliphatic hydrocarbons, alicyclic hydrocarbons, aromatic hydrocarbons, and halogenated hydrocarbons. Octane, isooctane, decane, isodecane, dodecane, isododecane, nonane, isoparaffin oil solvents Isopar E, Isopar G, Isopar H and Isopar L
(Isopar “Isopar” is a trade name of Exxon Co.), Solvetso 100, Siesol 71 (manufactured by Ciel) and the like are preferable.

When a colorant is used in the developer of the present invention, known pigments or dyes conventionally used for liquid developers or both of them can be used. For example, Hansa Yellow (CI11680), Benzidine Yellow G (CI2109
0), benzidine orange (CI21110), fare studded (CI37085), brilliant carmine 3B (CI160
15-Lake), Phthalocyanine Blue (CI74160), Phthalocyanine Green (CI74260), Victoria Blue (CI42595-Lake), Spirit Black (CI504)
15), Oil Blue (CI74350), Alkali Blue (CI42770A), Farst Scarlett (CI1231)
5), Rhodamine 6B (CI45160), Farst Sky Blue (CI74200-Lake), Nigrosine (CI50415),
There are carbon black etc. Surface-treated pigments, for example, carbon black dyed with nigrosine, graft carbon obtained by graft polymerizing a polymer, and the like can also be used.

Although not necessary in the present invention, a known dispersant can be used to enhance the dispersibility and stability of the liquid developer of the present invention. The dispersant is a resin that enhances the dispersibility of the toner, and is a resin that enhances the dispersibility of the toner by dissolving or swelling in the carrier liquid.
For example, rubbers such as styrene-butadiene, vinyltoluene-butadiene, butadiene-isoprene, etc., acrylic-based monomers having a long alkyl group such as 2-ethylhexyl (meth) acrylate, lauryl (meth) acrylate and stearyl (meth) acrylate. Polymers and copolymers of them with other monomers (styrene, (meth) acrylic acid and its methyl, ethyl, propyl ester, etc.), and further graft copolymers and block copolymers are used. be able to. Among these preferred dispersants,
Synthetic rubber-based dispersants are effective, and random or block copolymers of styrene-butadiene copolymer can be used as extremely effective dispersants.

When a charge control agent is used in the present invention, conventionally known charge control agents can be used. For example, metal salts of fatty acids such as naphthenic acid, octenoic acid, oleic acid and stearic acid, metal salts of sulfosuccinic acid esters, JP-B-45-55.
6, oil-soluble sulfonic acid metal salts shown in JP-A-52-37435, JP-A-52-37049, etc., metal salts of phosphoric acid ester shown in JP-B-45-9594, JP-B-48-25666 Metal salts of abietic acid or hydrogenated abitic acid shown in JP-A-55-2620, Ca-alkynebenzenesulfonic acid Ca-hydrochloride shown in JP-B-55-2620, JP-A-52-107837 and JP-A-52-3893.
7, metal salts of aromatic carboxylic acids or sulfonic acids described in JP-A-57-90643 and JP-A-57-139753, nonionic surfactants such as polyoxyethylated alkylamines, lecithin, Oils and fats such as linseed oil, polyvinylpyrrolidone, polyhydric alcohol organic acid esters, JP-A-57
-210345 phosphoric ester surfactants,
The sulfonic acid resin and the like shown in Japanese Examined Patent Publication No. 56-24944 can be used. In addition, JP-A-60-21056 and JP-A-61515
The amino acid derivatives described in 0951 can also be used. The amino acid derivative is a compound represented by the following general formula (2) or (3) or a reaction mixture obtained by further reacting a reaction mixture obtained by reacting an amino acid with a titanium compound in an organic solvent with water. .

(In the formula, R ₃ and R ₄ are hydrogen atoms, an alkyl group having 1 to 22 carbon atoms, a substituted alkyl group (as a substituent, a dialkylamino group, an alkyloxy group, an alkylthio group), a carbon number of 6
To 24 aryl groups, substituted aryl groups (substituents include dialkylamino, alkyloxy, alkylthio, chloro, bromo, cyano, nitro, and hydroxyl groups), aralkyl groups, and 1 to 22 carbon atoms , An arylsulfonyl group, an alkylphosphonyl group, an arylsulfonyl group and an arylphosphonyl group having 6 to 24 carbon atoms. R _3, R ₄ be the thickness respectively the same may be different connexion, may form a ring with R ₃ -R ₄ is not a hydrogen atom at the same time. A represents an alkylene group having 1 to 10 carbon atoms or a substituted alkylene group. X represents a hydrogen atom, a monovalent to tetravalent metal, or a quaternary ammonium cation. n shows a positive integer. Among these, preferable examples include metal salts of naphthenic acid, metal salts of dioctylsulfosuccinic acid, basic barium sulphonate, lecithin and the above amino acid derivatives. More preferred are zirconium, cobalt and manganese salts of naphthenic acid, calcium and sodium salts of dioctylsulfosuccinic acid, basic barium sulphonate and metal salts of the compound of the general formula (2). Examples of the metal salt of the compound of the general formula (2) include titanium, cobalt, zirconium,
Nickel salt is particularly preferred.

As these charge control agents, two or more compounds can be used in combination.

The liquid developer of the present invention can be manufactured by a conventionally known method.

In the case of using a colorant, first, a pigment or dye, or a colorant composed of both surfaces thereof and a coating agent which is a copolymer of the present invention are heated to a softening temperature of the coating agent or higher, and a Banbury mixer, a co-kneader, a kneader or a planetary is used. The mixture is kneaded using a kneader such as a mixer or a three-roll mill, and the mixture is cooled to obtain a mixture. In addition, various solvents and the like can be added during the kneading. As a method for obtaining the mixture, in addition to the above, the coloring agent and the coating agent are kneaded in a lyophilic solvent by a kneading machine such as a ball mill, a planetary mixer, a kneader, and a paint shaker, and the kneaded material is dried or A mixture can be obtained by adding to a non-solvent.

As another method, there is also a method described in JP-A-61-180248, in which a coating agent and a coloring agent are heated and plasticized and kneaded in a solvent such as Asoper L to obtain a spongy mixture when cooled. It is valid.

If necessary, the mixture thus obtained is crushed by a funnel press, a pin mill or the like, and then wet pulverized by a sand grinder, a dyno mill, a ball mill or the like together with a dispersant, if necessary, to obtain a developer concentrate. create. The solvent at the time of wet pulverization may be a supporting liquid, or a solvent such as toluene or acetone may be added.

The toner concentrate thus obtained is dispersed in a non-aqueous solvent containing a charge control agent to prepare a liquid developer for electrophotography. The concentration of toner particles in the developer is not particularly limited, but is usually 0.01 g to 100 g, preferably 0.1 g to 20 g, relative to the carried liquid 1. The coating agent in the toner particles is contained in an amount of 0.1 to 20 parts by weight, preferably 0.5 to 20 parts by weight, based on 1 part by weight of the coloring agent.
10 parts by weight can be used.

The concentration of the dispersant is usually 0.01 to 50 with respect to 1 carrier liquid.
g, preferably 0.1 to 10 g. The charge control agent may be added by an addition method other than the above method. That is, they may be added during kneading or wet pulverization, or may be used in combination. It is desirable to adjust the amount of the charge control agent to be contained in an amount of 0.001 g to 10 g per developer 1. More preferably, it is in the range of 0.01 g to 1 g.

The developer of the present invention can be used for a photoreceptor using a known organic photoconductor or inorganic photoconductor.
The developer of the present invention is also used for developing an electrostatic latent image generated by a means other than photosensitive, that is, charging of a dielectric by a charging needle.

Organic photoconductors include a wide range of well-known organic photoconductors. A specific example is "Resarch Disclosure" magazine # 10938 (1
From May 973, p. 61 and after, there are substances described in "Paper entitled" Electrophotographic Elements, Materials and Processes ").

Practical examples include, for example, poly-N-
Vinylcarbazole and 2,4,7-trinitrofluorene-
Electrophotographic photoreceptor comprising 9-one (US Pat. No. 3,484,23)
9), poly-N-vinylcarbazole sensitized with a pyrylium salt dye (Japanese Patent Publication No. Sho 48-25658), electrophotographic photoreceptors containing organic pigment as a main component (Japanese Patent Laid-Open No. 49-37543), dyes and resins. There are electrophotographic photoreceptors containing a eutectic complex consisting of and as a main component (JP-A-47-10735), and electrophotographic photoreceptors in which copper phthalocyanine is dispersed in a resin (JP-B-52-1667).

In addition, p.25 of the Electrophotographic Society of Japan, Vol. 3, No. 3 (1986).
The substances described in 62 to 76 are mentioned.

The developer of the present invention is disclosed in JP-B-37-17162 and JP-A-55-190.
63, JP-A-55-161250, JP-A-57-147656, and an organic photoconductor dispersed in an alkali-soluble resin such as a phenol resin as a conductive support such as aluminum. It can also be used as a developer having excellent etching resistance in the method of producing a printing plate which has been coated and developed with a developer and then etched with an alkaline aqueous solution.

Inorganic photoconductors are typically various inorganic compounds disclosed in "Electrophotography" by RM Schaffert, Focal Press (London) Publishing (1975), pages 260 to 374, and the like. Specific examples include zinc oxide, zinc sulfide, cadmium sulfide, selenium, selenium-tellurium alloy, selenium arsenic alloy, selenium-tellurium arsenide alloy, and the like. Amorphous silicon can also be mentioned.

[Effect of the Invention] The liquid developer containing the ethylene copolymer of the present invention has good transferability, is stable in dispersibility and chargeability over a long period of time, and has excellent resolution and excellent image quality. Gave.

"Examples" Examples of the coating agent production example and the liquid developer of the present invention are shown below, but the present invention is not limited by these.

Example-1 TK loss double planetary mixer 130LDM type (manufactured by Tokushu Kika Co., Ltd.) was charged with components having the following composition at 95 ° C. for 1 hour,
The mixture was stirred and kneaded at a rotation speed of 50 rpm.

Under these conditions, 9 parts by weight of Isopar L was added in portions over 2 hours, and the kneading was continued.

Next, this kneaded product was discharged into a stainless steel plate and cooled to room temperature to obtain a sponge-like kneaded product.

This kneaded product is a paint shaker (Toyo Seiki Co., Ltd.) having the following composition and glass beads of about 4 mm in diameter as media.
Was prepared and pre-dispersed for 20 minutes.

The predispersion was wet-dispersed at 4500 rpm for 6 hours using a Dynomill KDL type (Shinmaru Enterprises Co., Ltd.) using glass beads having a diameter of about 0.75 to 1 mm as a media to obtain a thick dispersion.

Liquid developer-A was prepared by adding 1 g of the solid content of this dispersion per Isopar G1 and Bauriu Petronate (made by Witeco Chemical Co., Ltd.) as a charge control agent so that the solid content was 0.1 g.

Next, an ethylene / methacrylic acid copolymer (ethylene: methacrylic acid copolymerization ratio 0.964) sold as Nyukurel N-699 (manufactured by Mitsui Deupon Polychemical) instead of the copolymer of Compound Example-1 of the present invention. : 0.036 molar ratio) was used in the same manner except that a comparative liquid developer-
B was prepared.

These liquid developers were measured by a centrifugal sedimentation type light transmission method particle size measuring device (CAPA-500 manufactured by Horiba Ltd.) and a charge amount measuring device described in JP-A-57-58176. The charge amounts are shown in Table-1. Both polarities were negative.

Here, the charge amount T indicates the value of the developer bulk and the charge amount I
Indicates the value of the supernatant obtained by centrifuging the developer, that is, the value based on the ionic component in the carrier liquid. Here, the larger the value of (T-I), the larger the effective charge, and the smaller the value of (I / T), the smaller the value of the ionic component in the charge amount, which is advantageous as a developer.

The developer A has a smaller particle size and better dispersibility than the developer B. This is interpreted as an effect based on a long-chain alkyl group having an affinity for the carrier liquid introduced into the ethylene copolymer.

Comparing the chargeability, it can be seen that the developer-A has a larger bulk charge amount (T) than the developer-B, and the effective charge (T-I) described above is also large, and thus the chargeability is excellent.

Next, polycarbonate (trade name "Lexan 121" G.
E. company) 10 g, diarylamine compound 6 shown below
g, 60 mg of a styryl dye shown below as a sensitizer was dissolved in 80 ml of methylene chloride.

Then, this solution was coated on a 100-micron-thick polyethylene terephthalate film having a palladium vapor-deposited layer using a wire bar and then dried to remove the coating solvent, and a 6-micron-thick photoconductive layer was formed. A photographic photosensitive member was prepared. The surface of this film was charged to + 400V, and image exposure was performed through a positive type original document to generate an electrostatic latent image.

This electrostatic latent image was developed using the above-mentioned developer-A and developer-B for comparison. When comparing the images of A and B,
In the image of B, the roughness is noticeable in the edge portion and the image of the image, whereas in the image of A, there is almost no roughness.
Developer-A was found to have excellent image reproducibility.

Next, after a negative corona discharge (-6 kV) was applied on the imaged material, Fuji Photo Film Co., Ltd. PS plate F
When transferred on the aluminum plate used for PD-II by a method of applying corona discharge of the same polarity (minus) as the toner from the photosensitive material side, both transfer almost completely at a transfer rate close to 100% Was completed.

 The transfer rate was calculated by the following formula.

D _S : Image density before transfer on light-sensitive material D _R : Image density after transfer on light-sensitive material When comparing the transferred images, A shows better image transfer with less image flow and thicker image lines than B. I knew to give.

Next, a printing test of the images transferred on these aluminum plates was performed in the following procedure.

First, the aluminum plate on which the image was transferred was heated at 120 ° C. for 5 minutes to fix the image, followed by gumming and surface treatment. Next, a printing press (Davidson 500) was used to perform a printing durability test. As a result of the printing durability test, both A and B had a printing durability of 30,000 sheets or more, confirming good printing durability.

Example-2 The general formula (2) in the present specification for the dispersion liquid obtained in Example-1 In which R ₃ : n-C ₈ H ₁₇ , A = C ₂ H ₄ R ₄ : n-C ₁₃ H ₂₇ CO, n = 2, and X = Ti are contained in 1 × 10 ^-4 mol per Isopar G 1. Then, in the same manner as in Example-1, a developer-C and a comparative developer-D were produced. Table 2 shows the particle size and charge amount.

Here, the charge amount of the comparative developer-D is smaller than that of the developer-C, the effective charge is almost zero, and it can be seen that almost all of the charge is an ionic component. This shows that the chargeability can be changed in a preferable direction by esterifying the carboxyl group of methacrylic acid of the ethylene / methacrylic acid copolymer.

Next, when development was carried out in the same manner as in Example 1, a so-called double image, in which an image flowed and an image appeared around the image line, occurred in Comparative Developer-D. On the other hand, the developer-C showed excellent image reproducibility with no image deletion or double image and almost no roughness in the edge portion. Further, the transferability was good, and a transfer rate almost 100% was shown as in Example-1.

Examples-3 to 6 Developers E to H were prepared by kneading and dispersing in the same manner as in Example-1, except that the copolymers shown in Table 3 were used. Table 3 shows the particle size and charge amount.

It can be seen that all the developers are superior in dispersibility and chargeability as compared with the comparative developer-B of Example 1.

Next, when development was carried out in the same manner as in Example 1, all showed little image roughness and excellent image reproducibility. When the transferability was tested in the same manner as in Example 1, good transferability was exhibited at a transfer efficiency of 90 to 100%.

Example-7 When wet-dispersing the kneaded material obtained in Example-1, Sorprene 1205 (manufactured by Asahi Kasei, styrene-butadiene copolymer, copolymerization ratio of styrene and butadiene, 0.75: 0.25 weight ratio) was used as a dispersion polymer. The following compositions were made to coexist.

Dispersion was carried out in the same manner as in Example-1 to prepare Developer-I.

 Table 4 shows the measurement results of particle size and charge amount.

In the case where the dispersing polymer was coexisted, the dispersibility and the chargeability were improved as compared with those not coexisting. When the image was developed in the same manner as in Example-1, excellent image reproducibility was exhibited in which almost no image flow or rough edges were observed. As a result of testing transferability, the transfer efficiency was 95 to 100%, which showed good transferability.

Example-8 TK loss double planetary mixer 130 LDM type (manufactured by Tokushu Kika Co., Ltd.) was charged and kneaded at 95 ° C. for 1 hour at a rotation speed of 50 R.PM and kneaded. Under these conditions, 37
Part by weight was added and stirring was continued for 1 hour to obtain a mixture. Next, this mixture was cooled to 50 ° C., and then added to 200 parts by weight of Asoper H to obtain a reprecipitate.

Thereafter, dispersion was carried out in the same manner as in Example-1, and a charge control agent was added to prepare Developer-J. The particle size and charge amount are shown in Table-5. A developer having almost the same physical property values as in Example 1 was obtained.

Next, development, transfer and printing were performed in the same manner as in Example 1, and as a result, it was confirmed that the developer A had the same performance as that of the developer A of Example 1.

Claims (1)

(57) [Claims] 1. A liquid developer for electrostatic charge images, characterized in that the carrier liquid contains at least one copolymer represented by the following general formula (I) as a constituent. In the formula, R ₁ represents a hydrogen atom or a methyl group. R ₂ is an unsubstituted or substituted alkyl group having 6 or more carbon atoms, a benzyl group, an aryl group having an alkyl group having 2 or more carbon atoms or a sulfonic acid group as a substituent, an alkyloxy group,
It represents an alkyloxycarbonyl group or a dialkylcarbonyl group. x and y represent the number of moles, and x: y = 0.995 to 0.80: 0.005 to 0.2
It is.