JPH087473B2 - Liquid developer for electrostatic photography - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a liquid developer for electrostatography comprising at least a resin dispersed in a carrier liquid having an electric resistance of not less than 10 ⁹ Ωcm and a dielectric constant of not more than 3.5. In particular, the present invention relates to a liquid developer having excellent redispersibility, storage stability, stability, image reproducibility, and fixability.

(Prior Art) A general liquid developer for electrophotography is an organic or inorganic pigment or dye such as carbon black, nigorosine or phthalocyanine blue, and a natural or synthetic resin such as alkyd resin, acrylic resin, rosin or synthetic rubber, which are petroleum-based. A polar control agent such as a polymer which is dispersed in a liquid having a high insulating property and a low dielectric constant such as an aliphatic hydrocarbon and further contains a metal soap, lecithin, linseed oil, a higher fatty acid and a polymer containing vinylpyrrolidone.

In such a developer, the resin is dispersed as insoluble latex particles in the form of particles having a diameter of several nm to several hundreds nm, but in a conventional liquid developer, a soluble dispersion stabilizing resin, a polarity control agent and insoluble latex particles are used. Due to insufficient bonding of the above, the soluble dispersion stabilizing resin and the polarity control agent were in a state of being easily diffused in the solution. For this reason, there is a drawback that the soluble dispersion stabilizing resin is separated from the insoluble latex particles by long-term storage or repeated use, and the particles settle, aggregate, or accumulate, or the polarity becomes unclear. Further, since particles once aggregated and accumulated are difficult to redisperse, the particles remain attached to various parts of the developing machine, leading to the failure of the developing machine such as dirt on the image area and clogging of the liquid feeding pump.

In order to improve these drawbacks, means for chemically bonding the soluble dispersion stabilizing resin and the insoluble latex particles have been devised and disclosed in US Pat. No. 3,990,980. However, the dispersion stability of these liquid developers against spontaneous sedimentation of particles has been improved to some extent, but it is still insufficient, and when used in an actual developing device, the toner adhered to each part of the device becomes a coating film. In addition, it is difficult to re-disperse, and furthermore, it is not sufficient for re-dispersion stability which can be used practically, for example, it causes a failure of the apparatus, stains of a copied image, and the like. Further, in the method for producing resin particles described above, in order to produce monodisperse particles having a narrow particle size distribution, there are significant restrictions on the combination of the dispersion stabilizer used and the insolubilizing monomer, and generally, The particles have a wide particle size distribution and contain a large amount of coarse particles, or are polydisperse particles having two or more average particle sizes. In addition, it was difficult to obtain a desired average particle size with monodisperse particles having a narrow particle size distribution, and large particles of 1 μm or more or very fine particles of 0.1 μm or less were formed. Further, there is a problem that the dispersion stabilizer to be used must be produced through a complicated and time-consuming production process.

Furthermore, in order to improve the above-mentioned drawbacks, insoluble dispersed resin particles of a copolymer of a monomer to be insolubilized and a monomer containing a long-chain alkyl moiety or a monomer containing two or more polar components. The method of improving the degree of dispersion of particles, redispersibility, storage stability by the method described in JP-A-60-179751, 62-15
It is disclosed in 1868 and the like.

(Problems to be Solved by the Invention) On the other hand, in recent years, a method of printing a large number of 5,000 or more sheets using a master plate for offset printing by an electrophotographic method has been attempted. It has become possible to print 10,000 sheets or more in plate size. In addition, the operation time of the electrophotographic plate making system has been shortened, and the development-fixing process has been speeded up.

The dispersed resin particles produced according to the means disclosed in JP-A-60-179751 and JP-A-62-151868, when the developing speed is increased, in terms of dispersibility of the particles, redispersibility,
In addition, when the fixing time is shortened or when a master plate of a large plate size (for example, A-3 size or more) is used,
In terms of printing durability, the performance was not always satisfactory.

The present invention solves the problems of the conventional liquid developer as described above.

SUMMARY OF THE INVENTION An object of the present invention is to provide a liquid developer which has a fast development-fixing process and has excellent dispersion stability, re-dispersibility and fixability even in an electrophotographic plate making system using a large-size master plate. That is.

Another object of the present invention is to provide a liquid developer which enables the production of an offset printing original plate having excellent oil sensitivity and printing durability by electrophotography.

Another object of the present invention is to provide a liquid developer suitable for various kinds of electrophotography and various kinds of transfer in addition to the above-mentioned applications.

Still another object of the present invention is to provide a liquid developer that can be used in any system in which a liquid developer can be used, such as ink jet recording, cathode ray tube recording and recording of various changing steps such as pressure change or electrostatic change. Is.

(Means for Solving the Problems) An object of the present invention is to have an electric resistance of 10 ⁹ Ωcm or more and a dielectric constant.
In a liquid developer for electrostatic photography, in which at least a resin is dispersed in a non-aqueous solvent of 3.5 or less, the dispersed resin particles are soluble in the non-aqueous solvent and do not contain a graft group capable of polymerizing with a monomer. In the presence of a resin, a monofunctional monomer (A) soluble in the non-aqueous solvent but insolubilized by polymerization and the following general formula (I)
Carboxyl group, sulfo group, hydroxyl group only at one end of the main chain of the polymer consisting of repeating units represented by
Formyl group, amino group, phosphono group, and An oligomer having a number average molecular weight of 10 ⁴ or less, which is formed by bonding at least one polar group selected from R ⁰ represents a hydrocarbon group or —OR ¹ group (R ¹ is a hydrocarbon group) (B )
Are copolymer resin particles obtained by subjecting a solution containing at least one kind to a polymerization reaction.

General formula (I) In formula (I), X is -COO-, -OCO-, -CH ₂ OCO-, -CH ₂
COO-, -O-, -SO _2- , Or Represents (R ² represents a hydrogen atom or a hydrocarbon group having 1 to 18 carbon atoms).

 Y represents a hydrocarbon group having 1 to 22 carbon atoms.

a ¹ and a ² may be the same or different from each other, and each is a hydrogen atom, a halogen atom, a cyano group, a hydrocarbon group having 1 to 8 carbon atoms, —COO—R ³ or a hydrocarbon group having 1 to 8 carbon atoms. Represents -COO-R ³ (R ³ represents a hydrogen atom or a hydrocarbon group having 1 to 18 carbon atoms).

 Hereinafter, the liquid developer of the present invention will be described in detail.

As a carrier liquid having an electric resistance of 10 ⁹ Ωcm or more and a dielectric constant of 3.5 or less used in the present invention, preferably a linear or branched aliphatic hydrocarbon, alicyclic hydrocarbon, or aromatic hydrocarbon, and a halogen thereof. Substitutes can be used. For example, octane, isooctane, decane, isodecane, decalin, nonane, dodecane, isododecane, Isopar E, Isopar G, Isopar H, Isopar L (Isopar; trade name of Exxon Corporation), Shersol 70, Shersol 71 (Shersol; Shell Oil Co., Ltd. product name), Amsco OMS, Amsco 460 solvent (Amsco; American Mineral Spirits product name), etc. are used alone or in combination.

Non-aqueous dispersion resin particles, which are the most important components in the present invention (hereinafter sometimes referred to as latex particles)
Is produced by polymerizing the monomer (A) and the oligomer (B) in the presence of a dispersion stabilizing resin in a non-aqueous solvent (so-called polymerization granulation method).

Here, as the non-aqueous solvent, basically any solvent can be used as long as it is miscible with the carrier liquid of the liquid developer for electrostatic photography.

That is, the solvent used for producing the dispersed resin particles may be any solvent that is miscible with the carrier liquid, and is preferably a linear or branched aliphatic hydrocarbon, alicyclic hydrocarbon, or aromatic hydrocarbon. And halogen substitution products thereof. For example, hexane, octane, isooctane,
Decane, isodecane, decalin, nonane, dodecane, isododecane, Isopar E, Isopar G, Isopar H, Isopar L, Shelsol 70, Shersol 71,
Amsco OMS, Amsco 460 Solvents are used alone or as a mixture.

Solvents that can be used in combination with these organic solvents include alcohols (eg, methyl alcohol,
Ethyl alcohol, propyl alcohol, butyl alcohol, fluorinated alcohol, etc.), ketones (eg acetone, methyl ethyl ketone, cyclohexanone, etc.), carboxylic acid esters (eg methyl acetate, ethyl acetate, propyl acetate, butyl acetate, methyl propionate, propione) Acid ethyl etc.), ethers (eg diethyl ether, dipropyl ether, tetrahydrofuran, dioxane etc.), halogenated hydrocarbons (eg methylene dichloride, chloroform, carbon tetrachloride, dichloroethane, etc.)
Methyl chloroform, etc.).

The non-aqueous solvent used as a mixture of these, after the polymerization granulation,
It is desirable to evaporate under heating or under reduced pressure.However, as a latex particle dispersion, even if brought into the liquid developer, there is a problem if the liquid resistance of the developer can satisfy the condition of 10 ⁹ Ωcm or more. No.

In general, it is preferable to use the same solvent as the carrier liquid in the step of producing the resin dispersion, and as described above, a linear or branched aliphatic hydrocarbon, an alicyclic hydrocarbon, an aromatic hydrocarbon, and a halogen. And the like.

The dispersion stabilizing resin necessary for forming a stable resin dispersion of the solvent-insoluble polymer produced by polymerizing the monomer in a non-aqueous solvent does not contain a graft group capable of polymerizing with the monomer. As the resin, a conventionally known dispersion stabilizing resin can be used. That is, various synthetic resins or natural resins soluble in a non-aqueous solvent are used alone or in combination of two or more.
For example, an alkyl chain or an alkenyl chain having a total carbon number of 6 to 32 [these aliphatic groups are halogen atoms, hydroxy groups,
Which may contain a substituent such as an amino group and an alkoxy group, or which may have a carbon-carbon bond in the main chain through a hetero atom such as an oxygen atom, a sulfur atom or a nitrogen atom, methacrylic acid Acid or ester acid of crotonic acid, higher fatty acid vinyls having 6 to 22 carbon atoms, alkyl vinyl ethers, polymers of olefins such as butadiene, isoprene, diisobutylene, etc., or copolymers of two or more kinds thereof, Further, as described above, the following monomers 1 and 2 are used in a ratio of the monomer forming a polymer soluble in a non-aqueous solvent and the copolymer obtained in a range soluble in a non-aqueous solvent.
A copolymer obtained by polymerizing one or more species can also be used.

Examples of the monomer include vinyl acetate, allyl acetate, methyl, ethyl, or propyl esters of unsaturated carboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, and itaconic acid, and styrene derivatives (for example, styrene). , Vinyltoluene, α-methylstyrene, etc.), unsaturated carboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, itaconic acid or acid anhydrides thereof, hydroxyethyl methacrylate, hydroxyethyl acrylate, diethylaminoethyl methacrylate, N -Vinylpyrrolidone, acrylamide, acrylonitrile, 2-chloroethyl methacrylate, 2,2,2-
Examples thereof include monomers containing various polar groups such as a hydroxy group, an amino group, an amide group, a cyano group, a sulfonic acid group, a carbonyl group, a halogen atom, and a hetero ring, such as trifluoroethyl methacrylate.

Alternatively, in addition to the above synthetic resin, alkyd resin,
Natural resins such as alkyd resins modified with various fatty acids, linseed oil and modified polyurethane resins can also be used.

The monomer (A) in the present invention may be any monofunctional monomer which is soluble in a non-aqueous solvent but insolubilized by polymerization. Specific examples include monomers represented by the general formula (II).

General formula (II) In formula (II), T is -COO-, -OCO-, -CH ₂ OCO-, -CH ₂ CO
O-, -O-, Represents Here, Z ¹ is a hydrogen atom or an optionally substituted aliphatic group of carbon soot 1 to 18 (eg, methyl group, ethyl group, propyl group, butyl group, 2-chloroethyl group, 2-
Bromoethyl group, 2-cyanoethyl group, 2-hydroxyethyl group, benzyl group, chlorobenzyl group, methylbenzyl group, methoxybenzyl group, phenethyl group, 3-phenylpropyl group, dimethylbenzyl group, fluorobenzyl group, 2-methoxyethyl A 3-methoxypropyl group).

Z represents a hydrogen atom or an optionally substituted aliphatic group having 1 to 6 carbon atoms (eg, methyl group, ethyl group, propyl group, butyl group, 2-chloroethyl group, 2,2-dichloroethyl group, 2,2 , 2-Trifluoroethyl group, 2-bromoethyl group, 2-glycidylethyl group, 2-hydroxyethyl group, 2-hydroxypropyl group, 2,3-dihydroxypropyl group, 2-hydroxy-3-chloropropyl group, 2
-Cyanoethyl group, 3-cyanopropyl group, 2-nitroethyl group, 2-methoxyethyl group, 2-methanesulfonylethyl group, 2-ethoxyethyl group, N, N-dimethylaminoethyl group, N, N-diethylaminoethyl group , Trimethoxysilylpropyl group, 3-bromopropyl group, 4-
Hydroxybutyl group, 2-furfurylethyl group, 2-tylnylethyl group, 2-pyridylethyl group, 2-morpholinoethyl group, 2-carboxyethyl group, 3-carboxypropyl group, 4-carboxybutyl group, 2-phosphoethyl group, 3-sulfopropyl group, 4-sulfobutyl group, 2
-Carboxyamidoethyl group, 3-sulfamidopropyl group, 2-N-methylcarboxamidoethyl group, cyclopentyl group, chlorocyclohexyl group, dichlorohexyl group, etc.).

b ¹ and b ² may be the same or different, each represent the same contents as a ¹ or a ² in the general formula (I).

Specific examples of the monomer (A) include, for example, 1 to 1 carbon atoms.
Unsaturation of vinyl esters or allyl esters of aliphatic carboxylic acids of 6 (acetic acid, propionic acid, butyric acid, monochloroacetic acid, trifluoropropionic acid, etc.), acrylic acid, methacrylic acid, crotonic acid, itaconic acid, maleic acid, etc. Alkyl esters or amides of carboxylic acid having 1 to 4 carbon atoms which may be substituted (eg, an alkyl group such as methyl group, ethyl group, propyl group, butyl group, 2-chloroethyl group, 2-bromoethyl group, 2-fluoroethyl group) Group, trifluoroethyl group, 2-hydroxyethyl group, 2
-Cyanoethyl group, 2-nitroethyl group, 2-methoxyethyl group, 2-methanesulfonylethyl group, 2-benzenesulfonylethyl group, 2- (N, N-dimethylamino)
Ethyl group, 2- (N, N-diethylamino) ethyl group, 2
-Carboxyethyl group, 2-phosphoethyl group, 4-carboxybutyl group, 3-sulfopropyl group, 4-sulfobutyl group, 3-chloropropyl group, 2-hydroxy-3-
Chloropropyl group, 2-furfurylethyl group, 2-pyridinylethyl group, 2-thienylethyl group, trimethoxysilylpropyl group, 2-carboxamidoethyl group, etc.), styrene derivative (eg, styrene, vinyltoluene, α-methyl) Styrene, vinylnaphthalene, chlorostyrene, dichlorostyrene, bromostyrene, vinylbenzenecarboxylic acid, vinylbenzenesulfonic acid, chloromethylstyrene, hydroxymethylstyrene, methoxymethylstyrene, N, N-dimethylaminomethylstyrene, vinylbenzenecarboxamide, Unsaturated carboxylic acid such as vinyl benzene sulfamide), acrylic acid, methacrylic acid, crotonic acid, maleic acid, itaconic acid or maleic acid, cyclic anhydride of itaconic acid, acrylonitrile, methacrylonitrile. , A heterocyclic compound containing a polymerizable double bond group (specifically, for example, compounds described in "Polymer Data Handbook-Basic Edition", edited by Japan Society of Polymer Science, p175-184, Baifukate (published in 1986). , For example, N-vinylpyridine, N-vinylimidazole, N-vinylpyrrolidone, vinylthiophene, vinyltetrahydrofuran,
Vinyloxazoline, vinylthiazole, N-vinylmorpholine and the like).

 Two or more monomers (A) may be used in combination.

The oligomer (B) is an oligomer having a number average molecular weight of 10 ⁴ or less, which is formed by bonding the above-mentioned specific polar group to only one end of the main chain of a polymer comprising a repeating unit represented by the general formula (I). It is.

The hydrocarbon groups contained in a ¹ , a ² , X and Y in the general formula (I) each have the indicated carbon number (as an unsubstituted hydrocarbon group), but these hydrocarbon groups are substituted. May be.

In the formula (I), R ² in the substituent represented by X is not only a hydrogen atom but also a preferable hydrocarbon group having 1 to 1 carbon atoms.
18 optionally substituted alkyl groups (eg, methyl group,
Ethyl, propyl, butyl, heptyl, hexyl, octyl, decyl, dodecyl, hexadecyl, octadecyl, 2-chloroethyl, 2-bromoethyl, 2-cyanoethyl, 2-methoxycarbonylethyl Group, 2-methoxyethyl group, 3-bromopropyl group, etc.), an alkenyl group having 4 to 18 carbon atoms which may be substituted (eg, 2-methyl-1-propenyl group, 2-
Butenyl group, 2-pentenyl group, 3-methyl-2-pentenyl group, 1-pentenyl group, 1-hexenyl group, 2-
Hexenyl group, 4-methyl-2-hexenyl group, etc.),
An aralkyl group having 7 to 12 carbon atoms which may be substituted (for example, benzyl group, phenethyl group, 3-phenylpropyl group, naphthylmethyl group, 2-naphthylethyl group, chlorobenzyl group, bromobenzyl group, methylbenzyl group, An ethylbenzyl group, a methoxybenzyl group, a dimethylbenzyl group, a dimethoxybenzyl group or the like, an alicyclic group having 5 to 8 carbon atoms which may be substituted (for example, cyclohexyl group,
-Cyclohexylethyl group, 2-cyclopentylethyl group, etc.) or an optionally substituted aromatic group having 6 to 12 carbon atoms (eg, phenyl group, naphthyl group, tolyl group, xylyl group, propylphenyl group, butyl) Phenyl group, octylphenyl group, dodecylphenyl group, methoxyphenyl group, ethoxyphenyl group, butoxyphenyl group, decyloxyphenyl group, chlorophenyl group, dichlorophenyl group, bromophenyl group, cyanophenyl group, acetylphenyl group, methoxycarbonylphenyl group , Ethoxycarbonylphenyl group, butoxycarbonylphenyl group, acetamidophenyl group, propioamidophenyl group, dodecyloylamidophenyl group, etc.).

X is When represented by, the benzene ring may have a substituent.
Examples of the substituent include a halogen atom (eg, a chlorine atom and a bromine atom), an alkyl group (eg, a methyl group, an ethyl group, a propyl group, a butyl group, a chloromethyl group, a methoxymethyl group, and the like).

Y preferably represents a hydrocarbon group having 1 to 18 carbon atoms,
Specifically, the same contents as those described above for R ² are represented.

a ¹ and a ² may be the same or different from each other, preferably a hydrogen atom, a halogen atom (for example, a chlorine atom,
Bromine atom, etc.), cyano group, alkyl group having 1 to 3 carbon atoms (eg, methyl group, ethyl group, propyl group, etc.), -COO
-R ³ or -CH ₂ COOR ³ (R ³ represents a hydrogen atom or an alkyl group having 1 to 18 carbon atoms, an alkenyl group, an aralkyl group, an alicyclic group or an aryl group, which may be substituted. Specifically, it represents the same contents as those described for R ² ).

More preferably, either ^one of a ¹ and a ² in formula (I) is a hydrogen atom.

A polar group which is bonded to only one end of a polymer main chain having a number average molecular weight of 1 × 10 ⁴ or less containing at least one kind of the repeating unit represented by the general formula (I); In the group, R ⁰ represents a hydrocarbon group having 1 to 18 carbon atoms or an —OR ¹ group. The hydrocarbon group for R ⁰ preferably has 1 carbon atom.
To 8 optionally substituted aliphatic groups (for example, methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, butenyl group, pentenyl group, hexenyl group, 2-chloroethyl group, 2-cyanoethyl group, Cyclopentyl group, cyclohexyl group, benzyl group, phenethyl group, chlorobenzyl group, bromobenzyl group, etc.) or optionally substituted aromatic group (eg, phenyl group, tolyl group, xylyl group, mesityl group, chlorophenyl group, bromophenyl) Group, methoxyphenyl group, cyanophenyl group, etc.).

When R ⁰ represents a —OR ¹ group, R ¹ preferably has the same meaning as the hydrocarbon group of R ⁰ .

In the polar group of the present invention, the amino group is -NH ₂ , -NHR ⁴ or Represents R ⁴ , R ⁵ and R ⁶ represent a hydrocarbon group having 1 to 18 carbon atoms, preferably a hydrocarbon group having 1 to 8 carbon atoms, and specifically, the aforementioned hydrocarbon group of R ⁰ and Represent the same content.

Even more preferably, the hydrocarbon group of R ⁰ , R ¹ , R ⁴ , R ⁵ and R ⁶ is an optionally substituted alkyl group having 1 to 4 carbon atoms, an optionally substituted benzyl group, or an optionally substituted benzyl group. A phenyl group which may be mentioned is mentioned.

Here, the polar group has a chemical structure in which the polar group is directly bonded to one end of the polymer main chain or is bonded via an arbitrary linking group. Examples of the group connecting the component (I) and the polar group include a carbon-carbon bond (single bond or double bond) and a carbon-hetero atom bond (hetero atoms include, for example, an oxygen atom, a sulfur atom, a nitrogen atom, and a silicon atom). Atoms), and any combination of heteroatom-heteroatom bond atomic groups.

Among the oligomers (B) of the present invention, preferable ones are those represented by the formula (IIIa) or the formula (IIIb).

Formula (IIIa) Formula (IIIb) In the formulas (IIIa) and (IIIb), a ¹ , a ² , X and Y have the same contents as the symbols of the formula (I). Q represents the above-mentioned polar group bonded to one end of the formula (I).

W is a simple bond or [R ⁷ and R ⁸ represent a hydrogen atom, a halogen atom (eg, fluorine atom, chlorine atom, bromine atom, etc.), cyano group, hydroxy group, alkyl group (eg, methyl group, ethyl group, propyl group), etc.] , CH = CH, -O-, -S-, -COO-, -SO _2- , -NHCOO-, -NHCONH-, [R ⁹ and R ¹⁰ each independently represent a hydrogen atom, a hydrocarbon group or the like having the same content as R ² ] or the like, and are composed of a single linking group or any combination thereof. Represents a linking group.

When the upper limit of the number average molecular weight of the oligomer (B) exceeds 1 × 10 ⁴ , the printing durability is deteriorated. On the other hand, if the molecular weight is too small, soiling tends to occur, so it is preferably 1 × 10 ³ or more.

The oligomer (B) of the present invention is a homopolymer component or copolymer component selected from the repeating units represented by the general formula (I), or a single amount corresponding to the repeating unit represented by the general formula (I). It is composed of a copolymer component obtained by polymerizing the body with another monomer that can be copolymerized. Examples of the other monomer that serves as a copolymer component together with the polymer component of formula (I) include acrylonitrile, methacrylonitrile, and a polymerizable double bond group-containing heterocyclic compound (specifically, a single amount. A compound similar to the heterocyclic compound described in the form (A)), a compound containing a carboxamide group or a sulfamide group and containing a polymerizable double bond group (for example, acrylamide, methacrylamide, diacetone acrylamide, 2-carboxamide). (Ethyl methacrylate, vinylbenzene carboxamide, vinylbenzene sulfamide, 3-sulfoamidopropyl methacrylate, etc.)
Etc.

The repeating unit represented by the general formula (I) is 30% by weight to 100% by weight in the oligomer (B) used in the present invention.
Wt% is suitable, preferably 50-100 wt%
Is.

Also, in the polymer main chain phosphono group, carboxyl group,
Sulfo group, hydroxyl group, formyl group, amino group, Those containing no copolymerizable component containing a polar group of groups are preferred.

The oligomer (B) of the present invention comprising a specific polar group bonded only to one end of the polymer main chain can be prepared by a method in which various reagents are reacted with the ends of a living polymer obtained by conventionally known anionic or cationic polymerization. (Method by ionic polymerization method), a method of radical polymerization using a polymerization initiator and / or a chain transfer agent containing a specific polar group in the molecule (method by radical polymerization method), or an ionic polymerization method as described above or It can be easily produced by a synthesis method such as a method of converting a polymer having a reactive group at a terminal obtained by a radical polymerization method into a specific polar group of the present invention by a polymer reaction.

Specifically, P.Dreyfuss, RPQuirk, Encycl.Polym.Sc
Review of i.Eng., 7 , 551 (1987), Yoshiki Chujo, Yuya Yamashita, "Dyes and Chemicals", 30 , 232 (1985), Akira Ueda, Susumu Nagai, "Science and Industry", 60 , 57 (1986) And the method described in the literature cited therein.

More specifically, examples of the oligomer (B) of the present invention include the following compounds. However, the scope of the present invention is not limited to these.

The dispersion resin of the present invention comprises at least one kind of each of the monomer (A) and the oligomer (B), and importantly, if the resin synthesized from these monomers is insoluble in the non-aqueous solvent. Thus, the desired dispersion resin can be obtained. More specifically, the oligomer (B) represented by the general formula (I) is preferably used in an amount of 0.05 to 10% by weight, more preferably 0.1 to 5% by weight, based on the insoluble monomer (A).
Is. Still more preferably, it is 0.3 to 3% by weight. The molecular weight of the dispersion resin of the present invention is 10 ³ to 10 ⁶ , preferably 10 ^{4 to} 5 × 10 ⁵ .

In order to produce the dispersion resin used in the present invention as described above, generally, the dispersion stabilizing resin and the monomer (A) as described above are used.
The oligomer and the oligomer (B) may be heat-polymerized in a non-aqueous solvent in the presence of a polymerization initiator such as benzoyl peroxide, azobisisobutyronitrile or butyllithium. Specifically, a method for adding a polymerization initiator to a mixed solution of a dispersion stabilizing resin, a monomer (A) and an oligomer (B), and a monomer (A) in a solution in which the dispersion stabilizing resin is dissolved. And a method of dropping the oligomer (B) together with the polymerization initiator,
Alternatively, a method of optionally adding the remaining monomer mixture together with the polymerization initiator to a mixed solution containing the whole amount of the dispersion stabilizing resin and a part of the mixture of the monomer (A) and the oligomer (B), And a method of optionally adding a mixed solution of a dispersion stabilizing resin and a monomer (A) and an oligomer (B) together with a polymerization initiator in a non-aqueous solvent, and the like. be able to.

The total amount of the monomer (A) and the oligomer (B) is about 5 to 80 parts by weight, preferably 10 to 50 parts by weight, based on 100 parts by weight of the non-aqueous solvent.

The amount of the soluble resin serving as the dispersion stabilizing resin is 1 to 100 parts by weight, preferably 5 to 50 parts by weight, based on 100 parts by weight of the total monomers used above.

The amount of the polymerization initiator is 0.1 to 5% (weight) of the total amount of the monomers.
Is appropriate.

The polymerization temperature is about 50 to 180 ° C., preferably 60 to 180 ° C.
~ 120 ° C. The reaction time is preferably 1 to 15 hours.

In the non-aqueous solvent used in the reaction, the alcohols described above,
When polar solvents such as ketones, ethers and esters are used in combination, or when the unreacted product of the monomer (A) to be polymerized and granulated remains, the boiling point of the solvent or monomer is increased. It is preferable to remove by heating or distilling off under reduced pressure.

As described above, the non-aqueous dispersion resin produced according to the present invention exhibits very stable dispersibility at the same time as being present as fine particles having uniform particle size distribution, and can be used repeatedly for a long time especially in a developing device. However, even if the dispersibility is good and the developing speed is improved, re-dispersion is easy, and it is not recognized at all that any contamination occurs on each part of the apparatus.

Further, when fixed by heating or the like, a strong film was formed, and excellent fixability was exhibited.

Furthermore, the liquid developer of the present invention is excellent in dispersion stability, redispersibility and fixability even when the development-fixing process is accelerated and a large plate size master plate is used.

When the resin particles of the present invention are used as a liquid developer, the details of the reason why the redispersion and the fixability of the toner image are significantly improved as described above are unknown, but in the polymerization granulation method of the resin particles of the present invention, Even after polymerization granulation without using the oligomer (B), the above effect was not observed even if the oligomer (B) was added by post-addition. This is considered that the oligomer (B) used in the resin particles of the present invention has modified the surface of the resin particles.

That is, because the polar group specified and bonded only to one end of the polymer main chain is polymerized and granulated in a non-aqueous solvent, it is bonded to the resin particles by an anchor effect, and the polymer main chain is It is presumed that one of the main factors is that the part modifies the surface of the resin particles and improves the affinity with the dispersion medium.

If desired, a colorant may be used in the liquid developer of the present invention.

The colorant is not particularly limited, and various conventionally known pigments or dyes can be used.

When the dispersed resin itself is colored, for example, as one of coloring methods, there is a method of physically dispersing it in a dispersed resin by using a pigment or a dye, and many pigments or dyes to be used are known. There is. For example, magnetic iron oxide powder, powdered lead iodide, carbon black, nigrosine, alkali blue, Hansa Yellow, quinacridone red, phthalocyanine blue and the like can be mentioned.

As another method of coloring, there is a method of dyeing a dispersed resin with a preferable dye as described in JP-A-57-48738. Alternatively, as another method, there is a method of chemically bonding a dispersion resin and a dye as disclosed in JP-A-53-54029, or JP-B-44-2.
As described in, for example, No. 2955, there is a method of producing a dye-containing copolymer by using a monomer containing a dye in advance when producing by a polymerization granulation method.

Various additives may be added to the liquid developer of the present invention as needed for the purpose of enhancing charging characteristics or improving image characteristics. For example, Yuji Harazaki, “Electrophotography”, Vol. 16, Vol. No. 4, p.44 is used.

For example, di-2-ethylhexyl sulfosuccinic acid metal salt, naphthenic acid metal salt, higher fatty acid metal salt, lecithin,
Examples include poly (vinylpyrrolidone) and a copolymer containing a semi-maleic acid amide component.

The amounts of the main components of the liquid developer of the present invention will be described below.

The toner particles containing a resin and a colorant optionally used as a main component are preferably 0.5 to 50 parts by weight with respect to 1000 parts by weight of the carrier liquid. If it is less than 0.5 parts by weight, the image density is insufficient, and if it exceeds 50 parts by weight, fog is easily generated on the non-image area. Further, the carrier liquid-soluble resin for stabilizing the dispersion described above is also used if necessary, and about 0.5 to 100 parts by weight can be added to 1000 parts by weight of the carrier liquid.
The charge control agent as described above is used for 1,000 parts by weight of the carrier liquid.
0.001 to 1.0 part by weight is preferable. Further, various additives may be added if necessary, and the upper limit of the total amount of these additives is restricted by the electric resistance of the developer. That is, the electric resistance of the liquid developer from which the toner particles have been removed is 10 ⁹ Ωcm.
If the value is lower, it is difficult to obtain a high quality continuous tone image. Therefore, it is necessary to control the amount of each additive within this limit.

(Examples) Examples of the present invention will be illustrated below, but the contents of the present invention are not limited thereto.

Production Example of Oligomer 1: Production of Oligomer B-1 A mixed solution of 100 g of methyl methacrylate, 5 g of thioglycolic acid, 150 g of toluene and 50 g of methanol was heated to 70 ° C. while stirring under a nitrogen stream. 1.5 g of 2,2'-azobis (isobutyronitrile) (abbreviation AIBN) was added and reacted for 4 hours. Furthermore, 0.4 g of AIBN was added and the reaction was carried out for 4 hours.

After cooling, the reaction solution was reprecipitated in 2 l of a mixed solution of methanol / water [(4/1) volume ratio], the methanol solution was separated by decantation, and the viscous substance was dried. 75 g was obtained. The number average molecular weight of the polymer was 2,800.

Oligomer Production Examples 2-12: Oligomer B-2 to B-12
Production Example 1 In Production Example 1, instead of 5 g of thioglycolic acid,
Respective oligomers B-2 to B-12 were produced in the same manner as in Production Example 1 except that the mercapto compound shown in Table 1 below was used. The number average molecular weight of the obtained oligomer is 2,500 to 3,5.
It was 00.

Oligomer Production Examples 13-23: Oligomer B-13-B-23
Production of Oligomer B-13 to B-23 was produced in the same manner as in Production Example 1 except that the monomers shown in Table 2 were used instead of methyl methacrylate. The number average molecular weight of the obtained oligomer was 2,500 to 3,500.

Oligomer Production Example 24: Production of Oligomer B-24 A mixed solution of 100 g of methyl methacrylate, 150 g of toluene and 50 g of ethanol was stirred under a nitrogen stream at a temperature of 75
Warmed to ° C. 8 g of 2,2'-azobis (cyanovaleric acid) (abbreviation ACV) was added and reacted for 5 hours, and further 2 g of ACV was added and reacted for 4 hours. After cooling the obtained reaction solution, it was reprecipitated in a mixed aqueous solution of methanol / water [(4/1) volume ratio]. The aqueous methanol solution was separated by decantation, and the viscous substance was dried. With a yield of 70 g, the number average molecular weight of the polymer was 2,600.

Oligomer Production Examples 25 to 33: Oligomer B-25 to B-33
Preparation of Oligomer B-25 to B-33 were prepared in the same manner as in Preparation Example 24 except that the azobis compound shown in Table 3 below was used instead of the polymerization initiator ACV. The number average molecular weight of the obtained oligomer was 2,000 to 4,000.

Example of production of latex particles: production of latex D-1 20 g of poly (octadecyl methacrylate), 100 g of vinyl acetate, 1.0 g of oligomer B-1 and 38 of Isopar H
0 g of the mixed solution was heated to a temperature of 70 ° C. with stirring under a nitrogen stream. 2,2'-Azobis (valeronitrile) (abbreviation AB
(VN) 0.8 g was added and reacted for 6 hours. Twenty minutes after the addition of the initiator, white turbidity occurred and the reaction temperature rose to 88 ° C. Temperature
The temperature was raised to 100 ° C. and the mixture was stirred for 2 hours to distill off unreacted vinyl acetate. After cooling, it was passed through a nylon cloth of 200 mesh, and the obtained white dispersion was a latex having a polymerization rate of 88% and an average particle size of 0.24 μm.

Production Examples 2 to 21 of Latex Particles: Latex D-2 to D
Production of −21 In the production example 1 of latex particles, oligomer B—
A white dispersion was obtained in the same manner as in Production Example 1, except that the oligomers shown in Table 4 below were used instead of 1. The polymerization rate of each white dispersion was 85 to 90%. The average particle size of each latex was in the range of 0.23 to 0.27 μm.

Production Examples of Latex Particles 22-35: Latex D-22-D
Production of -35 In Production Example 1 of latex particles, dispersion stabilizing resin poly (octadecyl methacrylate) and oligomer B were used.
A white dispersion was obtained in the same manner as in Production Example 1 except that each dispersion stabilizing resin and oligomer shown in Table 5 below were used instead of -1. The polymerization rate of the obtained dispersion was 85 to 90%.

Production Example 36 of Latex Particles: Production of Latex D-36 20 g of poly (octadecyl methacrylate), 100 g of vinyl acetate, 5 g of crotonic acid, 1.0 g of oligomer B-3 and 468 g of Isopar E are stirred under a nitrogen stream while stirring. The temperature was raised to 70 ° C. After adding 0.7g of ABVN and reacting for 6 hours, raise the temperature to 100 ° C and stir for 1 hour,
Residual vinyl acetate was distilled off. After cooling, it was passed through a 200-mesh nylon cloth, and the resulting white dispersion had a polymerization rate of 85%.
It was a latex having an average particle size of 0.23 μm.

Production Example 37 of Latex Particles: Production of Latex D-37 Poly (dodecyl methacrylate) 20 g, vinyl acetate 100
A mixed solution of g, 6.0 g of 4-pentenoic acid, 0.8 g of oligomer B-15 and 380 g of Isopar G was heated to 70 ° C while stirring under a nitrogen stream. 0.7 g of benzoyl peroxide was added and reacted for 4 hours, and then 0.5 g of benzoyl peroxide was added and reacted for 2 hours. After cooling, it was passed through a nylon cloth of 200 mesh, and the obtained white dispersion was a latex having an average particle size of 0.24 μm.

Production Example 38 of Latex Particles: Production of Latex D-38 A mixed solution of 85 g of vinyl acetate, 15 g of N-vinylpyrrolidone, 1.2 g of oligomer B-9 and 380 g of n-decane was stirred at a temperature of 75 ° C. under a nitrogen stream. Heated. AIBN 7g
The reaction was continued for 4 hours, 0.5 g of AIBN was further added and reacted for 2 hours. After cooling, the mixture was passed through a 200-mesh nylon cloth, and the obtained white dispersion was a latex having an average particle size of 0.20 μm.

Production Example 39 of Latex Particles: Production of Latex D-39 A mixed solution of 20 g of poly (octadecyl methacrylate), 100 g of methyl methacrylate, 1.0 g of oligomer B-19 and 470 g of n-decane was stirred at a temperature of nitrogen while stirring.
Heated to 70 ° C. AIBN (1.0 g) was added and reacted for 2 hours. Blue turbidity starts several minutes after the initiator is charged, and the reaction temperature is 90 ° C
Rose to. After cooling, coarse particles were removed through a 200-mesh nylon cloth, and the resulting white dispersion had an average particle size of 0.
It was a 45 μm latex.

Latex Particle Production Example 40 (Comparative Example A) In Latex Particle Production Example 1, the oligomer B-
The same operation as in Production Example 1 was repeated except that 1 was omitted. The obtained white dispersion was a latex having a polymerization rate of 85% and an average particle size of 0.25 μm.

Production Example 41 of Latex Particles (Comparative Example B) Production Example 1 of Latex Particles except that a mixed solution of 18 g of poly (octadecyl methacrylate), 100 g of vinyl acetate, 1.0 g of octadecyl methacrylate and 385 g of Isopar H was used. The same operation was performed.

The resulting white dispersion had a conversion of 85% and an average particle size of 0.22 μm.
Was latex.

Production Example 42 of Latex Particles (Comparative Example C) In Production Example 1 of latex particles, a mixed solution of 18 g of poly (octadecyl methacrylate), 100 g of vinyl acetate, 1 g of monomer (I) having the following chemical structure and 385 g of Isopar H is used. The same operation as in Production Example 1 was performed except that was used.

The resulting white dispersion had a conversion of 86% and an average particle size of 0.24 μm.
Was latex.

Monomer (I) Example 1 10 g of a dodecyl methacrylate / acrylic acid copolymer [copolymerization ratio (95/5) weight ratio], 10 g of nigrosine and 30 g of shell sol 71 were put together with glass beads in a paint shaker (Tokyo Seiki Co., Ltd.) for 4 hours. It was dispersed to obtain a fine dispersion of nigrosine.

Latex D-1 of Production Example 1
g, the above nigrosine dispersion 2.5 g, octadecene-half-maleic acid octadecylamide copolymer 0.08 g shell sol 7
By diluting to 1 to 1, a liquid developer for electrostatography was prepared.

(Comparative Developers A to C) In the production example of the liquid developer, latex D-1 was used.
Was replaced with the following latex, a liquid developer A for comparison,
Three kinds of B and C were produced.

Comparative Liquid Developer A: Latex Particle Production Example 40 Latex Comparative Liquid Developer B: Latex Particle Production Example 41 Latex Comparative Liquid Developer C: Latex Particle Production Example 42 Latex These liquid developers Was used as a developer for a fully automatic plate-making machine ELP404V (manufactured by Fuji Photo Film Co., Ltd.), and an electrophotographic photosensitive material ELP Master II type (manufactured by Fuji Photo Film Co., Ltd.) was exposed and developed. The plate making speed was 5 plates / minute. In addition, the ELP Master II type is 2000
After the sheet processing, it was observed whether or not the toner adhered to the developing device. The blackening rate (image area) of the copied image was determined using a 20% original. The results are shown in Table-6.

As described above, when each developer was subjected to plate making under the plate making conditions, the developer which did not cause staining of the developing device and had a clear image on the 2000th plate making plate was only in the case of the present invention.

On the other hand, a master plate for offset printing (ELP master) obtained by making a plate from each developer was printed by a conventional method, and the number of printed sheets until the occurrence of missing characters, blurred solid portions, etc. in the printed image was compared. Place, the present invention, Comparative Example A
The master plate obtained using the developer of Comparative Example C did not occur even when the number of sheets was 10,000 or more, and the master plate using Comparative Example B occurred when the number of sheets reached 8,000.

As described above, only the developer using the resin particles of the present invention as a developer did not cause any stain on the developing device, and also significantly improved the number of printed master plates.

That is, in the case of Comparative Example A, there was no problem in the number of printed sheets, but the developing device was significantly soiled and could not withstand continuous use.

In the case of Comparative Example B and Comparative Example C, when used at a high plate making speed of 5 sheets / minute (conventionally, at a plate making speed of 2 to 3 sheets / minute), the developing device (especially on the back electrode plate) was used. As a result, the image quality of the copied image on the plate is affected (reduced Dmax, fine lines, etc.) after 2000 sheets. The number of prints on the master plate was satisfactory in Comparative Example C, but decreased in Comparative Example B.

These results show that the resin particles of the present invention are clearly superior.

Example 2 100 g of the white dispersion obtained in Production Example 2 of latex particles
And a mixture of Sumicaron Black (1.5 g) was heated to a temperature of 100 ° C., and heated and stirred for 4 hours. By cooling to room temperature and passing through a 200 mesh nylon cloth to remove the remaining dye,
A black resin dispersion having an average particle size of 0.20 μm was obtained.

32 g of the above black resin dispersion, zirconium naphthenate 0.0
5g, Higher alcohol FOC-1400 (Nissan Chemical Co., Ltd.) 15g
Was diluted to 1 of Shell sol 71 to prepare a liquid developer.

When this was developed by the same apparatus as in Example 1, 2000
After the development of one sheet, the toner adhered to the device did not stain at all.

Further, the image quality of the obtained master plate for offset printing was clear, and the image quality of the printed matter after printing 10,000 sheets was also very clear.

Example 3 100 g of the white dispersion obtained in Production Example 36 of latex particles
And a mixture of 3 g of Victoria Blue B at a temperature of 70 ° C to 80 ° C.
And stirred for 6 hours. After cooling to room temperature, pass through a 200-mesh nylon cloth to remove residual dye, and average particle size of 0.
A 16 μm blue resin dispersion was obtained.

32 g of the above blue resin dispersion, zirconium naphthenate 0.0
5g, higher alcohol FOC-1600 (manufactured by Nissan Kagaku Co., Ltd.) 15g
Was diluted to 1 of Isopar H to prepare a liquid developer.

This was developed with the same apparatus as in Example 1, and
Even after the development of 00 sheets, no toner adhesion stains were observed on the apparatus. Further, the image quality of the obtained master plate for offset printing was clear, and the image quality of the printed matter after printing 10,000 sheets was also very clear.

Example 4 White resin dispersion 32 obtained in Production Example 3 of latex particles
g, 2.5 g of the nigrosine dispersion obtained in Example 1 and 0.02 g of a half-docosanilamide compound of a copolymer of diisobutylene and maleic anhydride were diluted to 1 of Isopar G to prepare a liquid developer.

When this was developed by the same apparatus as in Example 1, 2000
Even after sheet development, no toner adhesion stains were observed on the apparatus. The image quality of the obtained master plate for offset printing and the image quality of the printed matter after 10,000 sheets were printed were very clear.

After this developer was allowed to stand for 3 months, the same treatment as above was carried out, but there was no difference from that before the passage of time.

Example 5 10 g of poly (decyl methacrylate) and 3 parts of Isopar H
0 g and 8 g of alkali blue were put into a paint shaker together with glass beads, and dispersed for 2 hours to obtain a fine dispersion of alkali blue.

30 g of the white resin dispersion D-13 obtained in Production Example 13 of latex particles, 4.2 g of the above-mentioned alkali blue dispersion, 0.06 g of a semi-docosanyl amidated copolymer of octadecyl vinyl ether and maleic anhydride, and higher alcohol FOC- 14
A liquid developer was prepared by diluting 15 g of 00 to 1 of Isopar G.

When this was developed by the same apparatus as in Example 1, 2000
No toner adhesion stains on the apparatus were observed even after the sheet development. Further, the image quality of the obtained master plate for offset printing and the image quality of the printed matter after printing 10,000 sheets were very clear.

Examples 6 to 26 Each liquid developer was prepared in the same manner as in Example 5, except that the resin particles D-13 were replaced by the resin particles shown in Table 7 below.

When this was developed by the same apparatus as in Example 1, 2000
Even after sheet development, little or no toner adhesion stains were observed on the apparatus. Further, the image quality of the obtained master plate for offset printing and the image quality of the printed matter after printing 10,000 sheets were very clear.

(Effect of the Invention) According to the present invention, a developer having excellent dispersion stability, redispersibility, and fixability was obtained. In particular, even when used under plate-making conditions with extremely high plate-making speed, the developing device did not become stained, and the image quality of the obtained master plate for offset printing and the image quality of the printed matter after 10,000 sheets were printed were very clear. Was.

Claims (1)

[Claims] 1. An electrophotographic liquid developer comprising at least a resin dispersed in a non-aqueous solvent having an electric resistance of not less than 10 ⁹ Ωcm and a dielectric constant of not more than 3.5. In the presence of a resin which is soluble and does not contain a graft group which polymerizes with the monomer, the monofunctional monomer (A) which is soluble in the non-aqueous solvent but is insolubilized by polymerization and A carboxyl group, a sulfo group, a hydroxyl group, a formyl group, an amino group, a phosphono group, and a carboxyl group, a sulfo group, a hydroxyl group, and a An oligomer having a number average molecular weight of 10 ⁴ or less, which is formed by bonding at least one polar group selected from R ⁰ represents a hydrocarbon group or —OR ¹ group (R ¹ is a hydrocarbon group) (B )
Is a copolymer resin particle obtained by polymerizing a solution containing at least one of the following. General formula (I) In the formula (I), X is, -COO -, - OCO -, - CH 2 OCO -, - CH 2 CO
O-, -O-, -SO _2- , Or Represents (R ² represents a hydrogen atom or a hydrocarbon group having 1 to 18 carbon atoms). Y represents a hydrocarbon group having 1 to 22 carbon atoms. a ¹ and a ² may be the same or different from each other, and each is a hydrogen atom, a halogen atom, a cyano group, a hydrocarbon group having 1 to 8 carbon atoms, —COO—R ³ or a hydrocarbon group having 1 to 8 carbon atoms. Through-
COO-R ³ (R ³ represents a hydrogen atom or a hydrocarbon group having 1 to 18 carbon atoms).