JP2917298B2 - Liquid developer - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid developer (hereinafter, referred to as a liquid toner) used for developing an electrostatic latent image formed by an electrophotographic method or an electrostatic recording method. .

[Conventional technology]

An ideal liquid toner has a colorant and a fixing agent (a material having both dispersing performance, fixing performance and fixing performance) integrally bonded to each other, and the toner particles are stably dispersed in the electric insulator carrier liquid. It is necessary to be.

In order to solve this problem, the liquid toners described in JP-B-52-3306 and JP-B-56-10619,
A graft polymer obtained by grafting a vinyl polymer soluble in a carrier liquid and a vinyl polymer insoluble in the carrier liquid to each other by a reaction of a glycidyl group and a carboxyl group is used as a fixing agent. However, when such a liquid toner is repeatedly used for a long time or stored for a long time,
The dispersion stability of the liquid toner is deteriorated, the control of the charged electrode property is deteriorated with time, and the image density is thereby reduced. These are due to the fact that a relatively large amount of by-produced polymer soluble in the non-grafted carrier liquid elutes from the toner particles into the carrier liquid over time during the production of the graft polymer,
It is believed that the above-described ideal liquid toner configuration is caused by collapse.

Attempts have been made in recent years to improve the above-mentioned drawbacks of the graft polymer.For example, JP-A-59-83174 discloses that a carrier solution comprises a soluble polymer and an insoluble polymer. both the -COOH of the polymer, -SO ₃ H or -
A technique for improving the dispersion stability of a liquid toner by using a polar functional group of a soluble polymer and a polar functional group of an insoluble polymer by including a polar functional group such as OCOCH ₃ is disclosed. ing.

However, as a result of the study of the present inventors, as described above, in a liquid toner in which a polar functional group is simply added to a soluble polymer or an insoluble polymer, although the dispersion stability is improved to some extent, image bleeding or tailing occurs. Since pulling occurs, it has been found that there is still a problem in practice when used in a liquid developer for electrostatic development.

In order to improve the above-mentioned drawbacks of the liquid toner utilizing the adsorptivity between polar functional groups, for example, Japanese Patent Application Laid-Open No.
Japanese Patent No. 208057 discloses a liquid toner using a resin dispersion containing a carrier liquid-soluble copolymer containing an alicyclic or aromatic vinyl monomer and an insoluble polymer.

However, although such a resin dispersion improves image bleeding and tailing to some extent, the interaction between the soluble copolymer and the insoluble polymer is weak, so that the viscosity at 30% by weight of the nonvolatile content (B type) Viscometer) is dispersed in the form of a milky emulsion of less than 100 centipoise,
When the liquid toner is used, the dispersion stability is deteriorated, the control of the load polarity is deteriorated with time, and the image density is lowered due to long-term repetition or long-term storage.

In order to solve such a problem, the present inventors have:
JP-A-63-208866 proposes a gel latex-like stranded polymer having a viscosity of 100 centipoise or more at a non-volatile content of 30% by weight, which can be used for a long time or after a long-term storage. A liquid toner capable of maintaining good dispersion stability and good image density has been proposed.

[Problems to be solved by the invention]

The problem to be solved by the present invention is as described in the above-mentioned JP-A-63-20.
In the improvement of the liquid toner proposed in Japanese Patent No. 8866, the method for producing a chain polymer is improved, and even after long-time use or long-term storage, better dispersion stability and better image density are achieved. To provide a liquid toner capable of holding the toner.

[Means for solving the problem]

In order to solve the above problems, the present invention provides a vinyl copolymer 1 which is soluble in an electrically insulating carrier liquid and has entanglement between molecular chains.
And a vinyl copolymer 2 obtained by polymerizing a vinyl monomer containing a vinyl acetate monomer as a main component in a solution of the vinyl copolymer 1. The vinyl copolymer 1 The present invention provides a liquid toner using a chain copolymer insoluble in the carrier liquid as a fixing agent, wherein the vinyl copolymer 2 is in a state of being captured via mutual entangled portions.

In the present invention, an electrically insulating carrier liquid is used as a reaction medium for producing a copolymer and a carrier liquid for a liquid toner. Examples of the electrically insulating carrier liquid include, for example, hexane, pentane, octane, nonane, decane, undecane, dodecane, and other organic solvents such as organic solvents sold under the trade names such as `` Isoper GHKLM '' by Exxon Chemical Co., Ltd. 250
Various aliphatic hydrocarbon solvents having a boiling point in the temperature range of ° C., a volume resistivity of 10 ⁹ Ω · cm or more, and a dielectric constant of less than 3 can be used. Particularly, a solvent having a boiling point of 100 to 200 ° C., for example, “Isoper G” or “Isoper H” is preferable.

The liquid toner of the present invention is obtained by polymerizing a vinyl copolymer 1 which is soluble in the carrier liquid and has entanglement between molecular chains, and a vinyl monomer having a vinyl acetate monomer as a main component in the solution of the vinyl copolymer 1. Wherein the vinyl copolymer 2 is trapped by the vinyl copolymer 1 via a tangled portion between molecular chains. It is characterized in that a chain copolymer insoluble in a carrier liquid is used as a fixing agent.

The copolymer soluble in the carrier liquid is a copolymer having a chain segment for stabilizing the dispersion of the chain copolymer of the present invention, and (A) an alcohol having 8 to 24 carbon atoms. 45 to 95% by weight of a (meth) acrylate having a residue (hereinafter referred to as a first monomer component);
5 to 55% by weight of a (meth) acrylate having an alcohol residue of from 5 to 7 (hereinafter referred to as a second monomer component), and optionally another copolymerizable vinyl monomer component (hereinafter referred to as a third monomer component). )).

When the use ratio of the first monomer component is less than 45% by weight, the solubility in the carrier liquid is deteriorated, so that the dispersion stability of the toner tends to decrease, and the content of the first monomer component is 95% by weight. Exceeding the range is not preferred because the entanglement of the molecular chains with the vinyl monomer containing a vinyl acetate monomer as a main component is reduced, and the charge polarity stability of the toner tends to deteriorate.

Examples of the first monomer component include octyl (meth) acrylate, 2ethylhexyl (meth) acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate, and isononyl (meth) acrylate.

As the second monomer component, for example, methyl (meth)
Acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, butyl (meth) acrylate, isobutyl (meth) acrylate, tertiary butyl (meth) acrylate, cyclohexyl (meth) acrylate, benzyl (meth) Acrylate and the like can be mentioned. Particularly, a (meth) acrylate having an alcohol residue having 1 to 3 carbon atoms is preferable.

As the third monomer component, for example, (Wherein, R represents an alkyl group having 1 to 18 carbon atoms). (Wherein R represents an alkyl group having 1 to 18 carbon atoms.) A hydroxyl group-containing vinyl monomer such as a dialkyl ester of an unsaturated dicarboxylic acid or a hydroxyalkyl (meth) acrylate represented by the following formula: 6)
The vinyl monomer containing a carboxyl group, the vinyl monomer containing a phosphoric acid group, the vinyl monomer containing a sulfo group, or the vinyl monomer containing a halogen atom described in the above item; a vinyl monomer containing an epoxy group such as glycidyl (meth) acrylate; 2-methoxy of (meth) acrylic acid Ethyl, 2-ethoxyethyl ester; (meth) acrylonitrile; vinyl methyl ketone, vinyl isopropenyl ketone; styrene, vinyl toluene, α-methylstyrene; dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, N-vinyl Imidazole,
N-vinyl-2-methylimidazole, 1-vinylpyrrole, N-β-acryloxyethylindole, 2-vinylquinoline, 4-vinylpyridine, 5-vinyl-4-methylthiazole, 3-methyl-5-sopropenylpyrazole , N-vinyl-2-pyrrolidone, N-vinylpiperidone, N-vinyloxazolidone, dimethylaminostyrene, dimethylaminomethylstyrene, (meth) acrylamide basic nitrogen atom or amino group-containing vinyl monomer, and the like.

As a method for producing a vinyl copolymer soluble in the carrier liquid, for example, the carrier liquid can be used as a reaction solvent, and the first monomer component, the second monomer component and, if necessary, the third monomer component can be used. A method in which a polymerization reaction is performed in the presence of a known polymerization catalyst may be mentioned.

Examples of the polymerization catalyst include azobisisobutyronitrile, benzoyl peroxide, dibutyl peroxide, butyl peroxybenzoate, and the like, and the use amount is preferably in the range of 0.1 to 10.0% by weight of the monomer component.

The vinyl copolymer thus produced is at -30 ° C to 50 ° C.
It is soluble in the carrier liquid in the temperature range of

As a method for producing a chain copolymer insoluble in the carrier liquid of the present invention, for example, the carrier liquid can be used as a reaction solvent. A) 50 to 100% by weight of a vinyl acetate monomer and (B) 2 to 50% by weight of a vinyl monomer having a basic nitrogen atom or an amide group, and if necessary, other copolymerizable third monomer components, A method of polymerizing in a carrier liquid in the presence of the polymerization catalyst is mentioned. The chain copolymer thus produced is insoluble in the carrier liquid in the temperature range from -30 ° to 50 ° C.

Examples of the vinyl monomer having a basic nitrogen atom or an amide group include dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, N-vinylimidazole, N-vinyl-2methylimidazole, 1-vinylpyrrole, -Β-acryloxyethylindole, 2-vinylquinoline, 4-vinylpyridine, 5-vinyl-4-methylthiazole, 3-methyl-5-isopropenylpyrazole, N-vinyl-2
-Pyrrolidone, N-vinylpiperidone, N-vinyloxazolidone, dimethylaminostyrene, dimethylaminomethylstyrene, (meth) acrylamide and the like.

The ratio of the vinyl copolymer soluble in the carrier liquid and the vinyl monomer containing vinyl acetate as a main component is expressed in terms of weight ratio.
A range of 20:80 to 90:10 is preferred.

The use ratio of the vinyl copolymer soluble in the carrier liquid is 20.
If the amount is less than 10% by weight, the entanglement between the molecular chains is reduced, so that the dispersion stability of the toner tends to decrease, and the use ratio of the vinyl copolymer soluble in the carrier liquid is reduced.
If the content is more than 90% by weight, the charge polarity stability of the toner tends to deteriorate, which is not preferable.

The colorant used in the present invention is not particularly limited,
Conventionally known various dyes and / or pigments can be used, for example, carbon black, spirit black, aniline black, oil black, nigrosine, wool black, blue black E, alkali blue, phthalocyanine blue, oil blue, acid blue, Dianidin blue, pictoria blue, methylene blue, chrysoidine, sutan violet, crystal violet, oil violet, methyl violet, phthalocyanine green, acid black green, malachite green, safranin, brilliant carmine 6
B, Rhodamine 6G, Fast Red, Oil Red,
Congo Red, Auramine, Rhodamine B, Barium Red 2B, Calcium Red 2B, Strontium Red, Manganese Red 2B, Barium Sole Red, Calcium Red 52, Lake Red C, Formaloon L-58,
Brilliant Carmine 3B, Brilliant Scarlet G, Quinacridone Magenta, Bismarck Brown, Benzidine Yellow, Heiza Yellow, First Yellow G, First Yellow 10G, Disazo Yellow AAA, Disazo Yellow AAMX, Disazo Yellow AAOT, Disazo Yellow AOAA, Kayaset Yellow A-G , Kayaset Red B, Kayaset Blue FR, Kayaseron Yellow E
-5G, E-3GL, E-HGL, Kayaceron Red E-GL, E
-BF, E-2BL, Kayaceron Blue E-2BL, E-BR, E
-BG, E-5G, Kayaceron Torquay's Blue E-GL, Kayaceron Navy Blue E-EX, Kayaceron Black E
-EX, Kayaron Brilliant Flavin GL-SF, FG-S,
Kayaron Light Yellow 5GS, Kayaron Yellow HGL-S
F, YL-SE, 4R-E, PAL-E, Kayaron Red BR-S,
AD-S, TL-SF, BL-E, HL-SF, PAL-E, Kayaron Blue 3R-SF, CR-E200, 2R-SF, GR-E, EBL-E, P
AL-E, Kayaron Brilliant Blue FR-S, F2B-
S, Kayaron Torquee's Blue GL-S200, Kayaron Navy Blue GX-SF200, Kayaron Black S200, BR-S
F, EX-SF200 (all manufactured by Nippon Kayaku Co., Ltd.), Sumicaron Brilliant Flavin S-10G, Sumicaron Yellow SE-5G, S
E-3GL Cone, SE-RPD, E-RPD, SR, S-RPD, Sumicaron Orange SE-RPD, SR, Sumicaron Red E-3BR, S-BDF, E-RPD, E-FBL , S-BLF, SR
PD, S-BF, Sumicaron Blue S-3RF, E-GRL, SE-
RF, ER, E-BL, E-FBL, E-RPD, S-BG, SE-
RPD, Sumicaron Black S-BL, EB (N) (all manufactured by Sumitomo Chemical Co., Ltd.) and the like.

The dispersant used in the present invention, in combination with the chain copolymer of the present invention, which is the specific fixing agent, significantly improves the dispersion stability, storage stability, charge polarity stability and image density of the toner. Use to

As the dispersant for the positively chargeable liquid toner, for example,
Metal salts of naphthenic acid, octylic acid, and stearic acid are listed, and as the metal constituting the metal salt, Li, Ca, Ba, Z
Metals of Group II and Group IV of the periodic table, such as r, Mn, Co, Ni, Cu, Zn, Cd, Al, Pt, and Cr, and fiber metals are effective. In particular, a multimer, preferably a trimer of aluminum stearate and aluminum oxide acylate is preferable.

As a multimer of aluminum oxide acylate, for example, Olive ADS (manufactured by Hope Pharmaceutical Co., Ltd.) and Olive AOO (manufactured by Hope Pharmaceutical Co., Ltd.) are preferable.

As the auxiliary agent such as a dispersion stabilizer, any of those usually used in liquid developers can be used, for example, paraffin wax, polyethylene wax, polypropylene wax, ethylene copolymer, propylene copolymer and the like. Is mentioned.

The liquid toner according to the present invention comprises a fixing agent for the chain copolymer produced by the above method, a colorant such as a pigment or a dye, a dispersant, and, if necessary, an auxiliary agent such as a dispersion stabilizer. The mixture is uniformly milled with a ball mill, a sand mill, an attritor or the like to prepare a concentrated toner having a nonvolatile content of about 10 wt%, and the concentrated toner is dispersed in an electrically insulating carrier liquid comprising the aliphatic hydrocarbon solvent. It can be adjusted by diluting so that the amount is about 0.1 to 2%.

The electrophotographic method to which the liquid toner of the present invention is applied includes, for example, a wet copying machine, a printer, a plate making machine for a zinc oxide master, and a plate making machine for an OPC (organic optical semiconductor). Examples of the electrostatic recording method include a facsimile and an electrostatic plotter.

Since the liquid toner of the present invention uses a specific chain copolymer as a fixing agent, it has extremely excellent dispersion stability, and thus can maintain a good image density even when used for a long time.

〔Example〕

Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the following examples unless it exceeds the gist of the present invention. In the examples, "parts" means "parts by weight".

Production of Soluble Copolymer A copolymer soluble in an electrically insulating carrier liquid (hereinafter, referred to as a soluble copolymer) was produced according to the composition and the synthesis method shown in Table 1.

For comparison, a polymer without the second monomer component was produced.

Production of Chain Copolymer A chain copolymer was prepared from the soluble copolymer shown in Table 2 and a vinyl monomer component containing vinyl acetate as a main component. For comparison, milky white emulsions using Comparative Examples 1 and 2 as soluble copolymers were produced.

At that time, the polymerization catalyst and the reaction medium described in the same table were used, and the reaction conditions described in the same table were set.

Production of Liquid Toner Chain-like polymers, colorants, charge control agents,
The auxiliary agent and the carrier liquid are uniformly mixed and kneaded with a ball mill to produce a concentrated toner. For comparison, concentrated toners using the milky white emulsions of Comparative Examples 1 and 2 are produced, and the concentrated toner is diluted with the carrier liquid. did.

Table 3 shows the measurement results of dispersion stability and image density (Macbeth density) of each diluted toner.

As is evident from these results, the electrostatic plotters ("EP-10" manufactured by Matsushita Electric Transmission Co., Ltd.)
1) Type AM), Zinc Oxide Master plate making machine (Iwasaki Tsushinki Co., Ltd. "Elefax AP-3WDX") shows high image density of 1.0 or more, and good image quality even after continuous use for one month And the dispersion stability after standing for one month was also good.

However, the dispersion stability of the fixing agent of each developer of the comparative example is poor, so that the dispersion stability of the toner after standing for one month is poor. Happened.

In Table 3, Note 1 to Note 7 are trade names.

Note 1: Made by US Cabot Corporation Note 2: Made by Orient Chemical Co., Ltd. Note 3, Note 4, Note 5: Made by Dainippon Ink and Chemicals, Inc. Note 6: Made by Nippon Kayaku Co., Ltd. [Effect of the Invention] The fixing agent used in the present invention is A chain copolymer in which a vinyl copolymer having a vinyl acetate monomer insoluble in the carrier liquid as a main component is trapped by entanglement of molecular chains in a copolymer soluble in the electrically insulating carrier liquid. Therefore, the fixing agent and the colorant form toner particles in which the fixing agent and the colorant are integrally bonded to each other, and are stably dispersed in the carrier liquid. In addition, since the copolymer soluble in the carrier liquid is not eluted from the toner particles into the carrier liquid, the liquid developer of the present invention has high image density and good charge stability even in continuous repeated use. Having.

The liquid developer of the present invention having such excellent dispersion stability, high image density and good charge stability is suitable as a liquid developer used in developing various electrostatic latent images.

Claims (3)

(57) [Claims] 1. An electrically insulating carrier liquid comprising: (a) a vinyl copolymer 1 which is soluble in the carrier liquid and has entanglement of molecular chains, and a vinyl acetate monomer as a main component in a solution of the vinyl copolymer 1. And a vinyl copolymer 2 obtained by polymerizing a vinyl monomer to be produced, wherein the vinyl copolymer 2 is trapped by the vinyl copolymer 1 via a entangled portion of molecular chains. A toner for electrostatic latent images comprising toner particles containing: a fixing agent comprising a chain copolymer insoluble in the carrier liquid; (b) a colorant; and (c) a dispersant. In the liquid developer, the soluble vinyl copolymer comprises (A) 45 to 95 weight parts of (meth) acrylate having an alcohol residue of 8 to 24 carbon atoms and (B) alcohol residue of 1 to 7 carbon atoms. Having (meth) acrylate 5 An electrostatic latent image liquid developing agent which is a copolymer comprising a vinyl monomer mixture containing a 55 wt%. 2. A polymer of a vinyl monomer having a vinyl acetate monomer as a main component comprising: (A) 50 to 100% by weight of a vinyl acetate monomer; and (B) 2 to 50% by weight of a vinyl monomer having a chlorine-based nitrogen atom or an amide group. 2. The liquid developer for an electrostatic latent image according to claim 1, which is a polymer comprising a vinyl monomer mixture containing and. 3. A vinyl monomer having a basic nitrogen atom or an amide group is dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, N-
Vinylimidazole, N-vinyl-2-methylimidazole, 1-vinylpyrrole, N-β-acryloxyethylindole, 2-vinylquinoline, 4-vinylpyridine, 5-vinyl-4-methylthiazole, 3-methyl-
3. A vinyl monomer selected from the group consisting of 5-isopropenylpyrazole, N-vinyl-2-pyrrolidone, N-vinylpiperidone, N-vinyloxazolidone, dimethylaminostyrene, dimethylaminomethylstyrene, and (meth) acrylamide. Liquid developer for electrostatic latent images.