JPH0315740B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an electrostatic photographic liquid developer, more specifically, an electrostatic developer in which a colorant flushed with a specific resin and a specific polymer resin are dispersed as main components in a carrier liquid having high insulating properties and a low dielectric constant. This invention relates to a photographic liquid developer. General electrostatic photographic developers are mainly composed of colorants such as carbon black and synthetic or natural resins such as acrylic resins, phenol-modified resins, alkyd resins, rosins, synthetic rubbers, and lecithin, metallic soaps, linseed oil, etc. A toner containing a polarity control agent such as a higher fatty acid is dispersed in a carrier liquid made of a non-aqueous solvent having high insulation properties and a low dielectric constant, such as an aliphatic hydrocarbon solvent. However, with such liquid developers, the resin and polarity control agent desorb and diffuse into the carrier liquid over time, making the polarity unclear, and furthermore, the application material causes strong secondary aggregation, and is difficult to use in ball mills, attritors, or ultraviolet mills. Because it cannot be easily dispersed into primary particles even with ordinary equipment such as a sonic dispersion machine, the application material is exposed on the surface of the toner particles, and the transfer rate is affected due to variations in polarity controllability between particles. The image density is low, and the solid uniformity, sharpness, and resolution are insufficient. In addition, the toner has poor fixing properties, making it difficult to fix, especially on high-quality paper with high smoothness.Furthermore, the dispersion stability is poor and agglomerated toner tends to form, making it impossible to use the toner for a long period of time. In order to overcome this drawback, it is known to flash the colorant in advance and cover it with a resin. If a flushing resin that is soluble in the carrier liquid is used, the dissolved resin lowers the electrical resistance of the carrier liquid and destabilizes the polarity of the toner particles. In some cases, as a result of inversion, the image density may decrease or background stains may occur, making it impossible to form a clear image. Therefore, the flushing resin used is one that is insoluble or poorly soluble in the carrier liquid. However, when using resins that are insoluble in carrier liquids, such as polystyrene, methyl methacrylate, phenolic resins, and natural resin-modified resins, they have poor dispersibility and sedimentation due to their lack of affinity with the carrier liquid. Therefore, the sharpness due to the agglomerated particles was poor, and the resulting copies had poor drying properties and lacked fixing properties. Further, the above-mentioned conventional liquid developer for electrostatic photography is
Due to the lack of dispersion stability, toner tends to aggregate over time, and once aggregated, not only is it difficult to redisperse, but also the toner tends to adhere to the photoreceptor, resulting in a low transfer rate when transferring an image. However, there was a drawback that cleaning of the surface of the photoreceptor was poor. The present invention has been made in order to eliminate the above-mentioned drawbacks, and provides an electrostatic photograph with excellent toner dispersion stability, improved temporary fixing properties of copies, and excellent transferability and cleaning properties. The purpose of the present invention is to provide a liquid developer for use in liquid developers. That is, the electrostatographic liquid developer of the present invention is
The main components of the highly insulating and low dielectric constant carrier liquid are (1) polyethylene, polypropylene, vinyl chloride resin, poly(4-fluoroethylene) resin, and poly(4-fluoroethylene) resin.
- a coloring agent flushed with at least one resin selected from the group consisting of -fluorinated ethylene-6-fluorinated propylene copolymer resin, and (2) an acrylic or methacrylic resin having a fluorine atom in its side chain. It is characterized by dispersing toner particles. The colorant to be dispersed in the carrier liquid is one that has been subjected to flushing treatment. A flushed colorant is a common name for a particulate pigment coated with a resin, and is manufactured using a water-containing cake of organic or inorganic pigment. At least one selected from the group consisting of 4-fluorinated ethylene resin, poly 4-fluorinated ethylene-6-fluorinated propylene copolymer resin, polyethylene, polypropylene, and vinyl chloride resin is used. Note that the term "covering" as used herein does not necessarily mean that the entire outer surface of the particulate pigment is completely covered. Although polyethylene, polypropylene, and vinyl chloride resins are insoluble in the carrier liquid, they have a relative affinity for the carrier liquid and exhibit excellent dispersion stability. In addition, colorants treated with poly(4-fluoroethylene resin) and poly(4-fluoroethylene-6-fluoropropylene copolymer resin) have lower surface energy, improved primary fixing properties, and are free from solvents on the photoreceptor. It was found that it became difficult to adhere. Specific examples of commercially available flushing resins used in the present invention are shown below, and these can be used alone or in combination. (1) Polyethylene union carbide: DYNI, DYNF,
DYNJ, DYNK, Allied Chemical: AC Polyethylene 6 & 6 DuPont: Alathon 3, 10, 12, 14 Monsanto: Orizon 805, 705, 50 Philips: Marlex 100J Sanyo Chemical: Sanwax 131P, 151P, 161P,
165P, 171P, E200 Middle polyethylene: 2000 [melt index = 13, density = 0.957 (same below)], 3000 (7,
0.960), 4000 (4.5, 0.958), 4100 (6.5,
0.957), 8000B (0.2, 0.955), 5000 (1.0,
0.949), 6000 (0.8, 0.958), 7000 (0.7,
0.953), 2500 (9, 0.957) (2) Polypropylene Sanyo Chemical: Viscol 550P, 660P, (3) Vinyl chloride resin Electrical engineering: Denka Vinyl SS-110 [Polymerization degree
1040 (same below)], SS130 (1250), DSS−130
(1250), SS-140 (1400), SS-80 (850), SS
-70 (720), SS-Y (660), SH-250 (2500),
SH-170 (1700) [Suspension polymerized PVC straight polymer], M-70 (750), M-120
(1150), MM-90 (950), SM-140 (1400),
VP-30 [suspension polymerized PVC co-polymer], SE-130 (1350), ME-120 (1250),
ME−180 (1500), MHE−100 (1050), PA−
100 (1100), P-80 (900) [more than that, emulsion polymerization
PVC Straight & Co-polymer〕 (4) Fluoroplastics Mitsui Fluorochemicals: Teflon K (polytetrafluoroethylene resin) Teflon FEP (polytetrafluoroethylene-6
- Fluorinated propylene copolymer resin) Sumitomo 3M: Florard FC-721 (Poly 4-fluorinated ethylene resin) Regarding the colorant used in the present invention,
Examples of organic pigments include phthalocyanine blue, phthalocyanine green, sky blue, rhodamine lake, malachite green lake, methyl violet lake, peacock blue lake, naphthol green B, naphthol green Y, naphthol yellow S, litho first yellow 2G, and permanent trellis. Do 4R, Brilliant Fast Scarlet, Hansa Yellow, Benzidine Yellow, Resole Red, Lake Red C,
Lake Red D, Brilliant Carmine 6B, Permanent Red F5R, Pigment Scarlet
3B and Bordeaux 10B are used. Carbon black is a typical inorganic pigment used in the present invention, and furnace black, acetylene black, channel black, etc. can all be used, and commercially available pigments include Printex G, Special Black 15, Special Black 4, and Special Black. Black 4-B (manufactured by Degussa), Mitsubishi #44, #30, MA-11, MA-100 (manufactured by Mitsubishi Carbon), Raven 30, 40, and Conductex SC (manufactured by Cabot) are known. ing. The flushed colorant according to the present invention is obtained by kneading a water-containing paste consisting of a colorant and water with a flushing resin solution such as polyethylene, replacing the water surrounding the colorant with the resin solution, and then adding water and a solvent. It can be obtained by removing and pulverizing. It is preferable to use the coloring agent in an amount of about 10 to 60% of the flushing resin. The present invention, along with flushed colorants,
A specific polymer resin is dispersed in a highly insulating, low dielectric constant carrier liquid. It is an acrylic or methacrylic monomer polymer having a fluorine atom in it, or a copolymer of this monomer and another vinyl monomer, and by having a fluorine atom in the constituent unit, the toner has low energy. The toner adhering to the photoreceptor is easily separated, and the toners are less likely to aggregate with each other, so that an electrostatic photographic liquid developer with high dispersion stability and excellent transferability and cleaning performance can be obtained. Examples of acrylic or methacrylic monomers having a fluorine atom in the side chain include perfluorooctylfluoroethyl acrylate, 2-ethylhexylfluoroethylene methacrylate, perfluoro-2-ethylhexyl methacrylate, perfluoropentafluoroethylene methyl acrylate, and perfluoroethylbenzyl acrylate. , perfluoro-2,3-epoxy-2-ethyl acrylate, perfluoroacetobenzibenzizene para-octylfluoroethylene methyl acrylate, perfluoropentafluoroethylene methyl methacrylate, and the like. The polymer resin of the present invention is preferably a copolymer of this fluorine-containing acrylic or methacrylic monomer and another vinyl monomer. As the vinyl monomer to be copolymerized, the following general formula (1) is used.
Examples include monomers having acrylic ester, methacrylic ester, vinyl ether, or vinyl acetoester groups in which the alkyl group has 6 to 20 carbon atoms. [However, R is H or -CH ₃ , X' is -COOCnH ₂ n
+ ₁ , -OCnH ₂ n+ ₁ or -OCOCnH ₂ n+ ₁ (n=6
~20). ] Specific examples include lauryl methacrylate, lauryl acrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, octyl acrylate, stearyl methacrylate, lauryl vinyl ether, hexyl vinyl ether, lauryl vinyl ester, octyl vinyl ester, etc. There is. This monomer has the property of solvating with the solvent both before and after polymerization, and contributes to the dispersion stability and polarity stability of the toner. Styrene, vinyltoluene, unsaturated carboxylic acids, unsaturated nitrogen-containing compounds, or glycidyl group-containing unsaturated compounds are also useful copolymer-constituting monomers. The appropriate weight ratio of the monomer having a fluorine atom in the side chain to other monomers in the copolymer is about 60:95 to 5:40. To make a liquid developer using the copolymer obtained in this way, it is generally necessary to add 1 part by weight of the copolymer to 1 part by weight of the colorant.
0.3 to 3 parts by weight, and add this to a petroleum-based aliphatic hydrocarbon or halogenated 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 attritor, a ball mill, or a kedimir to obtain a concentrated toner, which is then diluted 5 to 10 times with a similar solvent. In this case, the copolymer dispersion obtained as described above can be used as is as the copolymer 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. The developer obtained in this way has a low viscosity, so it is easy to handle and can be sufficiently sucked when supplying toner to a copying machine.
It also has the advantage of being hard to harden even when stored for a long period of time. When polymerizing the monomer of the present invention, the polymerization initiator used is benzoyl peroxide, t-butyl perbenzoate, diamyl peroxide, di-t-butyl peroxide, lauryl peroxide, azobisisobutyronitrile. can be used. The carrier liquid used in the present invention is typically a petroleum aliphatic hydrocarbon or a halogenated aliphatic hydrocarbon, and specific examples thereof include kerosene, ligroin, n-hexane, n-pentane,
n-heptane, n-octane, i-octane, i
- Dodecane, i-nonane (commercially available products include Exxon's Isopar H, G, L, K; naphtha
No. 6 and Ciel Sol made by Ciel Sekiyu Co., Ltd.),
Examples include carbon tetrachloride and perfluoroethylene. Examples of the production of flushed colorants and polymer resins and electrostatographic developers according to the present invention will be described below. Production example 1 After thoroughly stirring 500g of water and 50g of Carbon Black Mitsubishi #44 with a flasher, add 150g of polyethylene (Hi-Zex; manufactured by Mitsui Chemicals) to it.
After kneading at 150° C. for 2 hours, 250 g of carbon tetrachloride was added and kneading was further continued for 2 hours. Then, the pressure was reduced to remove water and carbon tetrachloride, and the mixture was ground in a sweet mill. The powder diameter was 10-30μ. Production example 2 After thoroughly stirring 800 g of water and 80 g of phthalocyanine blue with a flasher, add 300 g of vinyl chloride resin (Denki Kagaku; SS-130) and mix 120 g of phthalocyanine blue.
Kneaded at ℃. Further, 50 g of perchlorethylene was added, and after kneading at 150°C for 3 hours, water and perchlorethylene were removed under reduced pressure. It was then ground to obtain a treated colorant with a particle size of 30-50μ. Production example 3 Fluorine resin (Florard FC-721) 50g Polyethylene AC-6 (Allied Chemical)
After sufficiently stirring 80g of toluene at 100℃ in a flasher, 50g of phthalocyanine blue (manufactured by Dainichiseika Chemical Co., Ltd.) wet cake (60% moisture content) was added, and after kneading at 150℃ for 4 hours, the water and toluene were mixed under reduced pressure. The volatile matter was removed. Then, it is crushed to a particle size of 8 to 15μ and a moisture content of 0.82%.
of powder was obtained. Production example 4 After thoroughly stirring 500g of water and 100g of carbon black (Mogul A; manufactured by Kyabot Co., Ltd.) using a flasher, add Florado to it.
Add 100g of FC-721 (fluororesin manufactured by 3M) and 100g of toluene, and heat at 120℃ (stir while dropping) for about 4 hours.
After kneading for an hour, the volatile matter was removed under reduced pressure and the mixture was pulverized. The particle size was 20-50μ and the water content was 1.2%. Production Example 5 120g of polypropylene (Viscol 660P) and 50g of toluene were heated to 100°C and thoroughly stirred in a flasher. 100g of phthalocyanine green wet cake (60% moisture content) and 50g of carbon black were added, heated at 150℃, and dispersed for 5 hours.
Volatile components were removed under reduced pressure. When crushed well, the particle size is 3.
~10μ, water content 1.8%. Production Example 6 300g of Teflon K and 150g of chlorobenzene were heated to 150°C in a flasher and stirred well. Then, 300 g of alkaline blue wet cake (water content 50%) was added and flushed at 150°C for 2 hours. After that, the pressure is reduced to remove volatile components, and then crushed in a sweet mill, the particle size is 5 to 10μ and the moisture content is
It was 0.38%. Manufacturing example 7 Polyethylene DYNF (made by Union Carbide)
300g of polypropylene was placed in a flatsher at 150%°C and kneaded. 250 g of benzidine yellow wet cake (moisture content: 75%) was placed therein and kneaded at 150°C for 3 hours. After that, the volatile content is dried under reduced pressure, and the particle size is 20~
A powder of 60 μm and water content of 1.2% was obtained. Production example 8 Monsanto Chemical's polyethylene orizon 705 is 200%
g and 100 g of vinyl chloride resin were placed in a flatsher and kneaded at 120°C. Into the mixture, 90 g of Special Black SB was placed in a flasher together with 50 g of toluene, and the mixture was kneaded at 100°C for 3 hours. It was then dried under reduced pressure to obtain a powder with a particle size of 18-36μ and a water content of 1.40%. Manufacturing example 9 200 g of Isopar G and 1 g of azobisisobutyronitrile are reacted at 90 to 100° C. for 8 hours, and after cooling, the obtained copolymer is collected. Yield 110g Production example 10 200 g of toluene and 1 g of azobisisobutyronitrile are reacted at 80 to 90°C for 10 hours, cooled and filtered to obtain 215 g of a copolymer. Manufacturing example 11 200g of toluene and 2g of azobisisobutyronitrile are reacted at 80-90°C for 12 hours, cooled and filtered to obtain 220g of a copolymer. Manufacturing example 12 200 g of toluene and 2 g of azobisisobutyronitrile are reacted at 90 to 100°C for 10 hours, cooled, and filtered to obtain 250 g of a copolymer. Manufacturing example 13 300 g of toluene and 2 g of azobisisobutyronitrile are reacted at 90 to 100°C for 15 hours, cooled, and filtered to obtain 260 g of a copolymer. Comparative Production Example 1 A coloring agent with a particle size of 10 to 30μ was prepared in the same manner as in Example 1, except that polyethylene was replaced with a diene polymer (trade name Hiretsu FTR-6090, manufactured by Mitsuishi Petrochemical Co., Ltd.). did. Example 1 50 g of the copolymer obtained in Production Example 12 18 g of the colorant obtained in Production Example 2 200 g of Isopar H was dispersed in a ball mill for 24 to 100 hours to obtain a concentrated toner, and 100 g of the concentrated toner was diluted with 1000 ml of Isopar H. A positively charged liquid developer was obtained. Example 2 70 g of the copolymer obtained in Production Example 10, 3 g of the colorant obtained in Production Example 4, and 200 g of Isopar H were treated in the same manner as in Example 1 to prepare a negatively charged liquid developer. Example 3 100 g of the copolymer obtained in Production Example 11, 10 g of the coloring agent obtained in Production Example 5, 20 g of 5% naphtha solution of manganese naphthenate, and 200 g of Isopar M were treated in the same manner as in Example 1 and developed with a positively charged liquid. A drug was prepared. Example 4 100 g of the copolymer obtained in Production Example 9, 20 g of the colorant obtained in Production Example 6, and 200 g of Isopar G were treated in the same manner as in Example 1 to prepare a positively charged liquid developer. Example 5 100 g of the copolymer obtained in Production Example 12, 20 g of the colorant obtained in Production Example 7, and 200 g of Isopar H were treated in the same manner as in Example 1 to prepare a positively charged liquid developer. Example 6 100 g of the copolymer obtained in Production Example 13, 20 g of the colorant obtained in Production Example 8, and 200 g of Isopar H were treated in the same manner as in Example 1 to prepare a positively charged liquid developer. Comparative Example 1 Coloring agent of Production Example 1 18g Lauryl methacrylate methacrylic acid copolymer
A liquid developer was obtained using 50 g of Isopar H and 200 g in the same manner as in Example 1. Comparative Example 2 Colorant of Comparative Production Example 1 18g Lauryl methacrylate methacrylic acid copolymer
A liquid developer was obtained using 50 g of Isopar H and 200 g in the same manner as in Example 1. Next, we used a wet-type plain paper electrophotographic copying machine using a commercially available Se photoreceptor (manufactured by Ricoh Co., Ltd., product name: DT1200).
A copying test was conducted by adding the liquid developers of the above Examples and Comparative Examples, and the copied image density, transfer rate, and cleaning performance were examined, and the results shown in the table below were obtained.

[Table] Note that the image copied using the liquid developer of Comparative Example 2 was a slightly blurred image. In addition, the developers of Examples and Comparative Examples did not cause precipitation or aggregation even after long-term storage, but when a copying test was conducted using them, the image density decreased in Examples 1 to 6 and Comparative Example 1. However, with the developer of Comparative Example 2, the image density decreased and the image had background smear.

Claims (1)

[Claims] 1. In a highly insulating, low dielectric constant carrier liquid, (1) polyethylene, polypropylene, vinyl chloride resin, poly(4-fluoroethylene) resin, and poly(4-fluoroethylene-6-fluoropropylene) are contained as main components. It is characterized by dispersing toner particles consisting of a colorant flushed with at least one resin selected from the group consisting of polymeric resins, and (2) an acrylic or methacrylic resin having a fluorine atom in its side chain. A liquid developer for electrostatic photography.