JPS60249156A - Liquid developer for electrostatic photography - Google Patents

Abstract

PURPOSE:To enable a high-quality image to be formed and to enhance fixability of an image by incorporating a copolymer resin obtained by polymerizing specified two kinds of monomers in the presence of a polymn. initiator in a solvent made of a petroleum-derived aliphatic hydrocarbon as a resin. CONSTITUTION:The resin used for the developer is prepared by polymerizing at least a monomer A represented by formula 1 having >=2 points having reaction activity different from each other in the molecule, and capable of giving cross- linked structure to the copolymer to be formed, with another monomer B of formula 2 having solvatability in solvents before or after the polymn., preferably, in an A/B weight ratio of (1-30)/(99-70), in the presenceof a polymn. initiator in the aliphatic hydrocarbon solvent. As a result, a copolymer resin having cross-linked structure and strong in polarity, stably dispersed in the aliphatic hydrocarbon solvent can be obtained by this polymn. reaction.

Description

DETAILED DESCRIPTION OF THE INVENTION TECHNICAL FIELD This invention relates specifically to improvements in binders used in electrostatographic liquid developer toners.

PRIOR ART Conventional liquid developers for electrostatic photography contain a coloring agent such as carzen black, an organic pigment or a dye, and a binder such as a synthetic or natural resin such as an acrylic resin, a phenol-modified alkyd resin, a rosin, or a synthetic rubber. The main ingredient is lecithin,
- A toner containing a polarity control agent such as metal soap, linseed oil, or higher fatty acid dispersed in a carrier liquid whose main component is a highly insulating, low dielectric constant solvent such as a petroleum-based aliphatic hydrocarbon. It is. In the development process, such toner causes electrophoresis in response to the charge of the electrostatic latent image formed on the six surface layers of the electrophotographic photosensitive material or electrostatic recording material, and adheres to that area to form an image. However, in conventional liquid developers, resins and polarity control agents diffuse into the carrier liquid over time, causing agglomeration and ambiguity in polarity, resulting in deterioration of image quality, especially image density. In addition to the significant problems, the adhesion of the toner and therefore the fixing power of the image were weak, and the durability when making continuous copies (the number of copies until the image density decreased to a predetermined level) was insufficient. The lack of durability is thought to be due to the fact that the pigment and resin constituting the toner are not sufficiently adsorbed in the carrier liquid, which causes the compositional balance of the developer to change as the number of copies increases.

OBJECTIVES The first object of the present invention is to provide an electrostatographic liquid developer capable of forming high quality images by clarifying the polarity of the toner and improving its storage stability.

A second object of the present invention is to provide an electrostatographic liquid developer which has improved image fixing properties by improving the adhesion of the toner.

A third object of the present invention is to provide a liquid developer for electrostatic photography that can greatly increase the number of durable sheets by increasing the adsorption power between the pigment and the resin.

Structure The electrostatic photographic liquid developer of the present invention is an electrostatic photographic liquid developer obtained by dispersing a toner containing a colorant and a binder resin as main components in a carrier liquid containing a petroleum-based aliphatic hydrocarbon as a main component. in the presence of a polymerization initiator in a petroleum-based aliphatic hydrocarbon solvent as the resin, at least a compound of the general formula I (where X is -H, -CH, or), and n is 1 to 1
(an integer of 0) and the general formula l CH,=CR' (where B is -H or -CH, R' is -COOCmHt
It is characterized by containing a copolymer resin obtained by polymerizing m+ or -ococma2m+, (m is an integer of 6 to 20) with monomer B.

The copolymer resin used in the present invention is thus prepared by polymerizing at least the monomer A of the general formula I and the monomer B of the general formula I in the presence of a polymerization initiator in an aliphatic hydrocarbon solvent. It will be done. The reaction with is carried out by heating the solvent,
The monomer used in this reaction process has two or more reactive active sites with different reactivities in the Ad molecule, giving the resulting copolymer resin a partially crosslinked structure.
On the other hand, monomer B has the characteristic that it is solvated in the solvent both before and after polymerization. Therefore, in this polymerization reaction, a highly polar copolymer resin having a crosslinked structure is stably dispersed in an aliphatic hydrocarbon solvent. Strength monomer A
The proportion of monomer B and monomer B is 1 to 30,799 to 70 parts by weight.
The degree is appropriate. Further, in this polymerization reaction, about 910 to 50 parts by weight of another polymerizable monomer C can be added and copolymerized per 100 parts by weight of the total amount of monomer A and monomer B.

Further, in the present invention, silica fine particles, wax or polyolefin having a softening point of about 60 to 130°C can be added to the resin manufacturing process. When fine silica particles are used, it is thought that the resin is obtained with the fine silica particles incorporated in its network structure. In this case, the silica itself is of course
During the reaction, it does not undergo any physical changes such as dissolution. In any case, in the case of silica, dispersion stability can be further improved by having a specific gravity similar to that of an aliphatic hydrocarbon as a dispersion medium and by preventing gelation of the resin. On the other hand, when wax or polyolefin is used, these are dissolved in the reaction system by heating during the polymerization reaction, but after the reaction, they are precipitated into fine particles by cooling, and the resin is obtained in a state that is adsorbed to these fine particles. considered to be a thing.

Here, wax or polyethylene has a specific gravity similar to that of the dispersion medium, prevents the resin from gelling, and has a molecular structure similar to that of the dispersion medium, so it is not a foolproof material that helps improve dispersion stability, and has a low softening point. , which also helps improve adhesion. The amount of silica, wax or polyolefin added is approximately 5 to 50 parts by weight per 100 parts by weight of the resin.

Next, the materials used in the present invention will be explained.

First, specific examples of monomer A of general formula I include the following.

h2 H2 H2 H2 H2 Monomer B of general formula (■) includes lauryl methacrylate, lauryl acrylate, stearyl methacrylate,
Stearyl acrylate, 2-ethylhexyl methacrylate, 2-ethylhexyl acrylate, dodecyl methacrylate, dodecyl acrylate, hexyl methacrylate, hexyl acrylate, octyl acrylate, octyl methacrylate, cetyl methacrylate,
Examples include cetyl acrylate, vinyl rough rate, and vinyl stearate.

As monomer C, polar monomers include unsaturated carzenic acid, unsaturated carboxylic acid anhydride, unsaturated nitrogen-containing compound, glycidyl group-containing unsaturated compound, alkyl acrylate (1 to 5 carbon atoms) ester, and/or alkyl methacrylate ( (C1-5) esters, etc. Here, examples of unsaturated caronic acids and their anhydrides include mori, acrylic acid, methacrylic acid, itaconic acid, fumaric acid, maleic acid, crotonic acid, aconitic acid, cinnamic acid, and their anhydrides. Examples of unsaturated nitrogen-containing compounds include vinylpyrrolidone, 2-vinylpyridine, 4-vinylpyridine, N-vinylpyridine, N-vinylimidazole, dimethylaminoethyl acrylate, dimethylaminoethyl methacrylate, etc. Examples of the alkyl (carbon number 1 to 5) ester of acid or methacrylic acid include methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, globyl acrylate, brol methacrylate, butyl acrylate, and butyl methacrylate. Further, typical examples of the unsaturated compound containing a glycidyl group include glycidyl acrylate and glycidyl methacrylate.

Other polymerizable monomers include styrene, vinyltoluene, vinyl acetate, polyhydric alcohol dimethacrylate (e.g. ethylene glycol diacrylate, ethylene glycol dimethacrylate, diethylene glycol diacrylate, diethylene glycol methacrylate,
Triethylene glycol triacrylate, triethylene glycol trimethacrylate, butanediol diacrylate, butanediol diacrylate diacrylate, 1,6-hexanediol diacrylate, trimethylolpro7centreacrylate, trimethylolzolonotrimethacrylate, tetramethylol Methane triacrylate, tetramethylolmethane trimethacrylate, tetramethylolmethanetetraacrylate, tetramethylolmethanetetramethacrylate, dizolo f-lene glycol diac.

rylate, dipropylene glycol dimethacrylate,
Trimethylolhexane triacrylate, trimethylolhexane trimethacrylate, pentaerythritol tetraacrylate, pentaerythritol tetramethacrylate, ■.

3-butylene glycol diacrylate, 1°3-butylene glycol dimethacrylate, trimethylolethane triacrylate, trimethylolethane methacrylate), and the like.

The polymerization initiators used when polymerizing these monomers A, B, and C include benzoyl peroxide, t-butyl, J-benzoate, cyamyl peroxide, di-t-
-Butyl peroxide, lauryl peroxide, azobisisobutyronitrile can be used.

Further, specific examples of commercially available waxes or polyolefins having a softening point of 60 to 130°C are as follows.

Union Carnoid (To) DYNI 102DYN
F 102 DYNH102 DYNJ 102 DYNK 102 Monsando @;) 0RLIZON 805 116u
705 116 tt 50 126 Philips (To) MARLEX 1005 92 Dupont (T) ALATHON -31031096 tt 12 84 N 14 80 p 16 95 tt, 20 86 tr 22 84 p 25 96 Allied Chemical @”) AC-Polyethylene 1702
98tt'6&6A 102 #615 105 Sanyo Chemical Sunwax 1at-p toss
15,1-P 107 tt 161-P 111 〃 165-P 107 # 171-P 105 tr E-20095 Lateral line of wax () rough-in wax) Seikagaku Nogra-in wax 60-98 Kobayashi Kako
Bleached beeswax 65 Setanol 80 Nagai Kako Bleached beeswax 65 Iron chemical Frozen 110 Petroleum-based aliphatic hydrocarbons used as reaction solvents or carrier liquids in the present invention include proyne, n-hexane, n=
"Exxon, n-hesotane, n-octane, l-octane, i-dodecane, 1-nonane (commercially available products include Exxon's Isonor H, G, L, Naphtha,
and Shell Sole manufactured by Shell Oil Co., Ltd.), tetracarboxylic carbon 5
These aliphatic hydrocarbons have a high flash point compared to aromatic solvents such as benzene and toluene, and are less toxic than aromatic solvents such as benzene and toluene. Since their solubility in resins is also lower than that of aromatic solvents, they also have the advantage that gelation or assimilation of resins is difficult to occur during polymerization reactions or storage.These petroleum-based aliphatic hydrocarbons have high insulating properties. (Electrical resistance 1010Ω
・It is a solvent with a low dielectric constant (dielectric constant of 3 or less).

Further, aromatic solvents such as benzene and toluene may be added to these aliphatic solvents in small amounts.

Next, an example of producing a copolymer resin (as a dispersion) will be shown.

Production Example 1 After stirring, 300.9 g of isooctane was poured into a 2.01 four-bottle flask equipped with a thermometer and a reflux condenser, and the mixture was heated to 95°C.
heated to. In this, dodecyl methacrylate 190I
I, methacrylic acid 1.09.71 it (1) monomer AI 0.9 and azobisip tyronitrile 6I!
After adding the different solution dropwise over 3 hours, the polymerization reaction was carried out by stirring for another 4 hours at the above temperature, and the polymerization rate was 96.4.
% and a viscosity of 380 ep was obtained. Note that the particle size of the resin was 0.3 to 2 μm.

Production Example 2 The resin dispersion 30011 obtained in Production Example 1 was mixed with colloidal silica 10II in a flask, heated at ioOoC for 3 hours, and then cooled to give a viscosity of 210 cp and a particle size of 1 to 3.
A resin dispersion containing colloidal silica of μ was obtained.

Production Example 3 300 g of indodecane was collected in the same flask as in Production Example 1 and heated to 90°C. Next, a solution consisting of lauryl methacrylate) 3001I, N-vinylzelidine 5p, monomer A25II of monomer (2) and benzoyl peroxide 3y was added dropwise to this over a period of 1.5 hours, and the mixture was heated at the above temperature for 4 hours. The polymerization reaction was carried out by stirring for hours, and the polymerization rate was 97.7% and the viscosity was 62.
0 ep.

A resin dispersion having a particle size of 4 to 7.5 μm was obtained.

Production Example 4 300J of the resin dispersion obtained in Production Example 3 was mixed with bleached beeswax 20.9 in a flask, stirred at 95°C for 22 hours, and then cooled to give a viscosity of 380ep and a particle size of 4.7 to 8μ. An exposed beeswax-containing resin dispersion was obtained.

Production Example 5 Isopar G300I and 30 g of colloidal silica were placed in the same flask as in Production Example 1 and heated to 90"C. 2-ethylhexyl methacrylate 150,9.
Glycidyl methacrylate) 151/5A (3) monomer A201! , methyl methacrylate 40I and lauroyl peroxide 6.3 g were added dropwise, and the mixture was further stirred at the above temperature for 4 hours to carry out a polymerization reaction.
A resin dispersion having a polymerization rate of 96.5%, a viscosity of 240 ep, and a particle size of 2 to 4 μm was obtained.

Production Example 6 In the same flask as in Production Example 1, 300 g of Isopar L and 60 g of polyethylene (AC-6 manufactured by Allied Chemical Co., Ltd.) were added. p
was added and heated to 95°C.

Next, stearyl methacrylate 18011 lauryl methacrylate) 40,9. Fumaric acid 31%A (4)
A solution of monomer A20JiF and lauryl china oxide 4II was added dropwise over 3 hours, and the polymerization reaction was carried out by further stirring at the above temperature for 3 hours, resulting in a polymerization rate of 944.
%, a viscosity of 260 ap and a particle size of 1 to 3 μm was obtained.

Production Example 7 Into the same flask as in Production Example 1, 300 g of Aitunogu-H and 180 g of cetyl methacrylate were added. f, dodecyl, acrylic 1
40 g of A(5) monomers Al 5f, acrylic acid 5I and benzoyl peroxide 3I), 90°C
The polymerization reaction was carried out by stirring for 6 hours, and the polymerization rate was 98.3%.
A resin dispersion having a viscosity of 320 cp and a particle size of 2 to 4 μm was obtained.

To make a liquid developer using the copolymer resin thus obtained, generally 1 part by weight of the colorant is mixed with 3 to 3 parts by weight of the copolymer, and this is mixed with 10 to 3 parts by weight of a petroleum-based aliphatic hydrocarbon carrier liquid. The toner may be sufficiently dispersed in the presence of 20 parts by weight using a dispersing machine such as an Attriter, Seel Mill, or Kudeimir to obtain a concentrated toner, which is then diluted 5 to 10 times with a similar solvent. In this case, the copolymer resin dispersion obtained as described above can be used as is as the copolymer resin and solvent. Further, when preparing a concentrated toner, other resins other than the copolymer of the present invention and a polarity control agent such as metal soap may be added to the mixture as necessary.

Since the developer thus obtained has a low viscosity, it is easy to handle and can be suctioned sufficiently when toner is supplied to a copying machine, and has the advantage that it is hard to harden even when stored for a long period of time.

Here, the colorants include carbon black, oil blue, alkali blue, phthalocyanine sol, phthalocyanine green, spirit black, aniline black, oil/metal iolet, benzidine yellow, methyl orange, brilliant carmine, fast red,
Examples include dyes or pigments such as crystal iolet.

Other resins that can be added to the developer include acrylic resins, ester gums, natural resins such as hardened rosins, and maleic acid resins modified with these natural resins, phenolic resins, polyesters, pentaerythritol resins, and the like.

The present invention will be explained below by way of examples.

Example 1 Carbon black (MA-11 manufactured by Mitsubishi Kazen Co., Ltd.) 10.9 50 g of the resin dispersion obtained in Production Example 1 and 100 g of kerosene were dispersed in a Kedi mill for 6 hours to obtain a concentrated toner with a viscosity of 16.8 cp. , 10.9 was dispersed in kerosene 11 to prepare a liquid developer for electrostatic photography.

Next, this developer was placed in a commercially available electrophotographic copying machine and copies were made on commercially available zinc oxide photosensitive paper, resulting in copies with an image density of 1.32 and an image fixation rate of 86.6%.

The fixing rate (%) was determined from the formula (image density after erasing 5 times in a rubber tester).

We also checked the durability of the developer by making continuous copies until the image density decreased to 0.60, and found that it was good at 25,000 copies.Furthermore, the developer was stored at 50℃ for 3 months. After forced deterioration, the image density was reduced by copying as described above and found to be 1.28, which showed almost no deterioration.

Examples 2 to 11 Using the pigments, resins, and dispersion medium shown in Table 1, liquid developers were prepared in the same manner as in Example 1 according to the dispersion method described in the table, and the same tests as in Example 1 were conducted. The results shown in Table 2 were obtained.

(The following is a blank space) Effects Since a highly polar crosslinked copolymer resin containing monomer A and monomer B as described above was used as the toner resin, the electrostatic photographic liquid developer of the present invention has clear polarity. , has good storage stability, and therefore can always form toner images of high quality and excellent fixing properties and durability.

Patent applicant Rico Co., Ltd.

Claims (1)

[Scope of Claims] 1. An electrostatic photographic liquid developer comprising a toner mainly composed of a colorant and a binder resin dispersed in a carrier liquid mainly composed of a petroleum-based aliphatic hydrocarbon, wherein the resin In a solvent consisting of a petroleum-based aliphatic hydrocarbon, in the presence of a polymerization initiator, at least the general formula! (However, X is -H, -CH, or halogen, and n is 1 to 1O
monomer A represented by the general formula ■ CH,=C (where Rd-H or -cm, * is -COOCmHtm
A liquid developer for electrostatic photography, comprising a copolymer resin obtained by polymerizing a monomer B represented by ++ or -〇〇〇〇mH2m++ (m is an integer of 6 to 20). .