JP2800153B2 - Liquid developer for electrostatic photography - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a liquid developer for electrostatography.

[Prior art] Generally, the migration speed of toner is calculated by the following equation. μ: migration speed of toner (cm / sec / V / cm) qs: surface charge density of toner (μ / cm ² ) ro: particle size of toner (μm) η: viscosity of solvent (cps) It is known that the particle size is larger than the particle diameter of the toner and the surface charge density of the toner.

Regarding the particle size of the toner used for the liquid developer for electrostatography, a toner having an average particle size of 0.01 to 1 μm and a mixture of 1 to 30 μm and having two particle size distribution peaks are used. .

According to JP-A-59-26743, in such a technology, a large particle size toner (toner particles having an average particle size distribution in a range of 1 to 30 μm) is made of Fe, Ni, Cu, Fe ₂ O ₃ , SiO ₂ , Z
Metals such as nO and TiO, metal compounds themselves, and dyes and pigments are dispersed or coated with resins such as vinyl chloride resin, styrene resin, acrylic resin, phenolic resin, rosin-modified maleic resin, petroleum resin, and butadiene resin. Stuff, glass balloon, shirasu balloon, activated carbon particles,
When composed of an electrophotographic dry toner or the like, the large-sized toner particles are not necessarily satisfied with properties such as heat resistance, chemical resistance, coefficient of friction, non-adhesion, and water / oil repellency, It is reported that it is difficult to provide high-resolution image quality and good fixability immediately after copying.

On the other hand, according to Japanese Patent Application Laid-Open No. 62-59967, it is reported that the above-mentioned defect is eliminated when the large-sized toner particles are composed of polytetrafluoroethylene.

However, according to experiments performed by the present inventors, this is still not enough, and particularly when it is desired to uniformly disperse an organic or inorganic dye or pigment in polytetrafluoroethylene or when the dye or pigment is made of polytetrafluoroethylene. If you want to coat evenly,
The fact is that the result is unsatisfactory.

〔Purpose〕

Accordingly, a first object of the present invention is to provide a liquid developer having good dispersion stability while utilizing the characteristics of the fluorine-based resin.

A second object of the present invention is to increase the density of a developed image,
Another object of the present invention is to provide a liquid developer for electrophotography which has good reproducibility of halftones and can be developed with high uniformity even in a large area image area.

A third object of the present invention is to provide a liquid developer having good fixability immediately after copying.

〔Constitution〕

The present invention relates to a highly insulating, low dielectric constant aliphatic hydrocarbon and / or halogenated hydrocarbon liquid having an average particle diameter of 0.01.
Small particle size group in the range of 1 to 1 μm and average particle size of 1 to 30 μm
In an electrostatographic liquid developer obtained by dispersing toner particles having two particle size distribution peaks each composed of a large particle size group in the range of the above, particles constituting the large particle size group are represented by the following general formula: It is characterized by being composed mainly of a copolymer of the monomer represented by (I) and fluoroacrylate and / or fluoromethacrylate.

Here, in the formula, R ₁ is H or CH ₃ , and n is 1 to 4.

As described above, the large particle size toner is made of a copolymer of the monomer represented by the general formula (I) and fluoroacrylate and / or fluoromethacrylate. To make this copolymer, for example, the above-mentioned general formula (I)
A known polymerization method may be used, for example, by heating and polymerizing a fluoroacrylate and / or fluoromethacrylate in benzene or toluene in the presence of a polymerization initiator such as benzoyl peroxide or azobisisobutyronitrile.

The copolymer thus obtained can be prepared by (a) uniformly dispersing, for example, an inorganic or organic dye or pigment in the copolymer, or (b) coating the dye or pigment with the copolymer.
1.0μm fine particles can be agglomerated into granules,
(C) A large particle group can be easily produced in a form such as a pigment aggregate or a capsule structure in which the periphery of the granular material is wrapped with the copolymer. The copolymer may be a hollow particulate polymer so that the specific gravity (preferably 0.5 to 1.4) can be adjusted.

The amount of the copolymer in the large particle size toner is about 0.01 to 10
A suitable amount is about weight%.

As described above, in the copolymer of the present invention, the portion represented by the general formula (I) in the molecular structure is easily compatible with organic or inorganic dyes and pigments, so that dispersion, coating, aggregation, and the like can be easily performed, and By the moiety consisting of fluoroacrylate and / or fluoromethacrylate,
The critical surface tension of this copolymer became γc = 13 dyne / cm or less, and it became possible to sufficiently maintain the water / oil repellency. Those represented by the general formula (I) are acrylates or methacrylates having 1 to 4 carbon atoms, such as acrylic acid, ethyl acrylate, propyl acrylate, and n-acrylic acid.
Butyl, iso-butyl acrylate, methacrylic acid, ethyl methacrylate, n-butyl methacrylate and the like can be used. The following are examples of the fluoroacrylate or fluoromethacrylate.

That is, 1,1-dihydroperfluoroethyl, 1,1-dihydroperfluoropropyl, 1,1-dihydroperfluorohexyl, 1,1-dihydroperfluorooctyl, 1,1-dihydroperyl of acrylic acid or methacrylic acid Fluorodecyl, 1,1-dihydroperfluorolauryl, 1,1,2,2-tetrahydroperfluorobutyl, 1,1,2,2-tetrahydroperfluorohexyl, 1,1,2,2-tetrahydroperfluoro Octyl, 1,1,2,2-tetrahydroperfluorodecyl, 1,1,2,2-tetrahydroperfluorolauryl, 1,1,
2,2-tetrahydroperfluorostearyl, 2,2,3,3-tetrafluoropropyl, 2,2,3,3,4,4-hexafluorobutyl, 1,1, ω-trihydroperfluorohexyl, 1 , 1, ω−
Trihydroperfluorooctyl, 1,1,1,3,3,3-hexafluoro-2-propyl, 3-perfluorononyl-2-acetylpropyl, 3-perfluorolauryl-2-acetylpropyl, N-perfluoro Hexylsulfonyl-N-
Methylaminoethyl, N-perfluorohexylsulfonyl-N-butylaminoethyl, N-perfluorooctylsulfonyl-N-ethylaminoethyl, N-perfluorooctylsulfonyl-N-ethylaminoethyl, N-perfluorooctylsulfonyl- N-butylaminoethyl, N-perfluorodecylsulfonyl-N-methylaminoethyl, N-perfluorodecylsulfonyl-N-ethylaminoethyl, N-perfluorodecylsulfonyl-N
Ester compounds such as -butylaminoethyl, N-perfluorolaurylsulfonyl-N-methylaminoethyl, N-perfluorolaurylsulfonyl-N-ethylaminoethyl, N-perfluorolaurylsulfonyl-N-butylaminoethyl and the like. Can be

When the ratio of the large particle size particles to the small particle size particles is more than 50 wt%, the sedimentation of the toner is large and the charge control by the small particle size toner is insufficient, and the image density is reduced. If it is less than 1 wt%, ro is too small and the migration speed of the toner becomes low, resulting in poor image density and uniformity. A more desirable ratio is 5 to 40% by weight of the large particle toner.

In order to obtain the toner of the present invention, a small particle toner and a large particle toner each containing a colorant and a binder resin as main components may be prepared and mixed.

As the binder resin of the small particle size particles, for example, a general formula in a petroleum aliphatic hydrocarbon or a halogenated aliphatic hydrocarbon solvent [Where R represents hydrogen or a methyl group, and A represents -COOCnH _{2n + 1} or -OCOCnH _{2n + 1} (where n is an integer of 6 to 20). And a copolymer obtained by polymerizing a monomer represented by the formula (hereinafter referred to as "monomer A") with divinylbenzene or an alkyl (C1-20) derivative thereof (hereinafter referred to as "monomer B"). Can be

To make this copolymer, the monomers A and B
May be heated and polymerized in a petroleum aliphatic hydrocarbon or halogenated aliphatic hydrocarbon solvent in the presence of a polymerization initiator such as benzoyl peroxide or azobisisobutyronitrile. By this reaction, a copolymer having a three-dimensional structure in which both components of the monomer A and the monomer B are cross-linked to each other is obtained.

The monomer B used in this reaction has a property of being solvated with the solvent before polymerization, but not solvated after polymerization. On the other hand, the monomer A has a property of solvating with the solvent before and after the polymerization. Therefore, the obtained copolymer has the monomer B component as the center in the solvent, and the monomer A component solvated with the solvent is dispersed around the monomer B component. Here, the monomer A in the copolymer
The components contribute to the improvement of the dispersion stability (accordingly, storage stability) and adhesion of the toner. The ratio of the monomer B to the monomer A is suitably about 0.01 to 1: 1 (polymerization). Also,
An appropriate amount of another polymerizable monomer (hereinafter, referred to as monomer C) can be added to the monomer A and monomer B components.

In order to prepare a liquid developer using the thus obtained copolymer, generally, the copolymer is used in an amount of from 0.3 to 3 parts by weight based on 1 part by weight of the colorant.
And 10 to 20 parts by weight of petroleum resin aliphatic hydrocarbon or halogenated aliphatic hydrocarbon solvent in an attritor, ball mill, Keddy mill, etc. The toner may be diluted 5 to 10 times with a similar solvent.

In this case, the copolymer dispersion obtained as described above can be used as it is as the copolymer and the solvent. When preparing the concentrated toner, a resin other than the copolymer of the present invention or a polarity controlling agent such as metal soap can be added to the mixture as needed. The developer thus obtained has a low viscosity and is easy to handle, and the low viscosity of the toner facilitates the mechanical replenishment of the toner in a copying machine and hardly causes the toner to gel or solidify during storage. It has the advantage.

Specific examples of the monomer A include lauryl methacrylate, lauryl acrylate, stearyl methacrylate, stearyl acrylate, 2-ethylhexyl methacrylate, 2-ethylhexyl acrylate, dodecyl methacrylate, dodecyl acrylate, hexyl methacrylate, hexyl acrylate, octyl methacrylate, octyl acrylate, cetyl Examples include methacrylate, cetyl acrylate, vinyl laurate, and vinyl stearate.

Examples of the monomer B include o-divinylbenzene, m
-Divinylbenzene, p-divinylbenzene, p-methyldivinylbenzene, o-ethyldivinylbenzene, p
-Butyldivinylbenzene, m-hexyldivinylbenzene, o-nonyldivinylbenzene, p-decyldivinylbenzene, o-undecyldivinylbenzene, p-stearyldivinylbenzene, o-methyldivinylbenzene, o-ethyldivinylbenzene, p- Hexyldivinylbenzene, p-nonyldivinylbenzene, m-decyldivinylbenzene, p-undecyldivinylbenzene,
o-stearyldivinylbenzene and the like.

Examples of the monomer C include styrene, vinyl toluene,
Alkyl (C1-5) ester of vinyl acetate, acrylic acid or methacrylic acid (for example, methyl methacrylate, ethyl acrylate, methyl acrylate, ethyl methacrylate, butyl methacrylate), polyhydric alcohol di (meth) acrylate (for example, ethylene glycol diacrylate) , Ethylene glycol dimethacrylate, diethylene glycol diacrylate, diethylene glycol methacrylate, triethylene glycol acrylate, triethylene glycol trimethacrylate, butanediol diacrylate, butanediol dimethacrylate, 1,6-hexanediol diacrylate, 1,6-hexanediol Dimethacrylate, trimethylolpropane triacrylate, trimethylolpropane trimethacrylate G, tetramethylol methane triacrylate, tetramethylol methane trimethacrylate, tetramethylol methane tetraacrylate, tetramethylol methane tetramethacrylate, dipropylene glycol diacrylate, dipropylene glycol dimethacrylate, trimethylol hexane triacrylate, trimethylol hexane trimethacrylate, Examples thereof include pentaerythritol tetraacrylate, pentaerythritol tetramethacrylate, 1,3-butylene glycol diacrylate, 1,3-butylene glycol dimethacrylate, trimethylolethane triacrylate, and trimethylolethane methacrylate.

Benzoyl peroxide, t-butyl perbenzoate, diamyl peroxide, di-t-
Butyl peroxide, lauryl peroxide, azobisisobutyronitrile and the like can be used.

Examples of the solvent include petroleum aliphatic hydrocarbons or halogenated aliphatic hydrocarbons, for example, kerosene, ligroin, n-hexane, n-heptane, n-octane, 1-octane,
-Dodecane (the above commercial products include Isopar H, G, K manufactured by Exxon; Naphtha No. 6; Solvesso 100, etc.), carbon tetrachloride, perfluoroethylene and the like. A small amount of an aromatic solvent such as toluene or xylene may be added to these aliphatic solvents.

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

Examples of the colorant include dyes or pigments such as carbon black, oil blue, alkali blue, phthalocyanine blue, phthalocyanine green, spirit black, aniline black, oil violet, benzidine yellow, methyl orange, brilliant carmine, fast red, and crystal violet. Can be

Examples of the polarity controlling agent include conventional ones such as metal soap, lecithin, linseed oil, and higher fatty acids.

As the small particle toner, a conventional wet toner (Ricoh type 1000, Ricoh type 1700, Ricoh BS toner, Ricoh MRP toner, etc.) may be used as it is.

(Production Examples, Examples)

Next, a production example of a resin dispersion liquid composed of a large particle toner,
Shows a production example of a resin dispersion composed of small particle toner,
Next, the present invention will be specifically described with reference to examples, but the scope of the present invention is not limited to the following examples.

Production Example 1 (Production of Resin Dispersion Consisting of Large Particle Particle Toner) 250 g of benzene was placed in a 500 ml four-necked flask equipped with a stirrer, thermometer and reflux condenser, and heated to 90 ° C. Among them, 51.8 g of methyl methacrylate is represented by the following formula.

A solution composed of 21.8 g of fluoromethacrylate and 1.5 g of azobisisobutyronitrile was added dropwise over 1 hour, and the mixture was further heated and stirred at 90 ° C. for 5 hours to carry out a polymerization reaction. A resin dispersion of ~ 3 µm was obtained.

Production Example 2 (Production of Resin Dispersion Consisting of Large Particle Particle Toner)
Warmed to ° C. In this, n-butyl acrylate 51.8 g,
It is shown by the following formula 21.8 g of fluoromethacrylate and 1.5 of benzoyl peroxide
g of solution over 1 hour, and then 9
The mixture was heated and stirred at 0 ° C. for 5 hours to carry out a polymerization reaction, and a conversion of 97.6 was obtained.
%, A resin dispersion having a viscosity of 280 cp and a particle size of 5 to 6 μm was obtained.

Production Example 3 (Production of Resin Dispersion Consisting of Large Particle Particle Toner)
Warmed to ° C. In this, 51.8 g of propyl methacrylate,
It is shown by the following formula 21.8 g of fluoromethacrylate and 1.5 of benzoyl peroxide
g of solution over 1 hour, and then 9
The polymerization reaction was carried out by heating and stirring at 0 ° C for 5 hours, and the polymerization rate was 98.7.
%, A resin dispersion having a viscosity of 300 cp and a particle size of 10 μm was obtained.

Production Example 4 (Production of Resin Dispersion Consisting of Large Particle Particle Toner) 250 g of benzene was placed in the same flask as in Production Example 1 above.
Warmed to ° C. In this, methacrylate-isobutyl 51.8
g, represented by the following formula A solution composed of 21.8 g of fluoromethacrylate and 1.5 g of azobisisobutyronitrile was added dropwise over 1 hour, and the mixture was further heated and stirred at 80 ° C. for 5 hours to carry out a polymerization reaction, a polymerization rate of 96.7%, a viscosity of 331 cp and a particle size of 23 μm. A resin dispersion was obtained.

Production Example 5 (Production of Resin Dispersion Consisting of Small Particle Particle Toner) After stirring, 300 g of isooctane was placed in a 2.0 four-necked flask equipped with a thermometer and a reflux condenser, and heated to 95 ° C. In this, dodecyl acrylate 190 g, o-butyldivinylbenzene 10 g and azobisisobutyronitrile 6 g
The resulting solution was added dropwise over 3 hours, and the mixture was heated and stirred at the above temperature for 4 hours to carry out a polymerization reaction. Degree of polymerization 94.8
%, A resin dispersion having a viscosity of 295 cp and a particle size of 0.1 to 0.20 μm was obtained.

Production Example 6 (Production of Resin Dispersion Consisting of Small Particle Particle Toner) 300 g of isododecane was placed in the same flask as in Production Example 5,
Heated to 90 ° C. Next, lauryl methacrylate
A solution comprising 300 g, 20 g of o-ethyldivinylbenzene and 3 g of benzoyl peroxide was added dropwise over 1.5 hours, and the mixture was further heated and stirred at 90 ° C. for 4 hours to carry out a polymerization reaction.
A resin dispersion having a polymerization rate of 96.5%, a viscosity of 400 cp, and a particle size of 0.1 to 0.3 μm was obtained.

Production Example 7 (Production of Resin Dispersion Consisting of Small Particle Particle Toner) 300 g of the resin dispersion obtained in Production Example 5 was mixed with 10 g of cetanol (Kobayashi Kako) in a flask, and stirred at 95 ° C. for 3 hours. Upon cooling, a resin dispersion having a viscosity of 190 cp and a particle size of 0.5 to 0.8 μm was obtained.

 Hereinafter, parts in Examples are parts by weight.

<Example 1> 15 parts of carbon black (M-11 manufactured by Mitsubishi Carbon Corporation) 70 parts of the resin dispersion obtained in Production Example 1 90 parts of the resin dispersion obtained in Production Example 5 100 parts of kerosene (all parts are weights) Is the same as in the following examples) is dispersed in a kedi mill for 6 hours to obtain a concentrated toner having a viscosity of 30 cp, and 10 g of the concentrated toner is dispersed in kerosene 1 to prepare a liquid developer for electrostatography. A toner in which toner particles having an average particle diameter of 0.6 μm and 5 μm were mixed was obtained.

Next, using this developer, a copy was performed on zinc oxide photosensitive paper with a commercially available electrophotographic copying machine, and a copy having an image density of 1.41 and an image fixing rate of 84.3% was obtained. The primary fixing property (fixing property immediately after copying) was also good.

For comparison, a developer prepared in the same manner except that the resin dispersion obtained in Production Example 1 was changed to Lubron L-5 had a low image density of 1.21 and a low image fixing rate of 71.4%.

The image fixing rate (%) was calculated from the formula of Y / X × 100 (X: image density before erasing, Y: image density of 5 reciprocations with an eraser tester).

<Example 2> 15 parts of phthalocyanine blue 75 parts of the resin dispersion obtained in Preparation Example 75 75 parts of the resin dispersion obtained in Preparation Example 0.5 0.5 parts of manganese naphthenate 100 parts of kerosene were dispersed in a Keddy mill for 6 hours to obtain a viscosity. A concentrated toner of 34 cp was used, and 10 g of the toner was dispersed in kerosene 1 to prepare a liquid developer for electrophotography. As a result, a toner in which toner particles having an average particle diameter of 0.4 μm and 8 μm were mixed was obtained.

Next, a copy was made on a zinc oxide photosensitive paper using a commercially available electrophotographic copying machine using this developer, and a copy having an image density of 1.38 and an image fixing rate of 83.2% was obtained. The primary fixing property (fixing property immediately after copying) was also good.

The image fixing rate (%) was calculated from the formula of Y / X × 100 (X: image density before erasing, Y: image density of 5 reciprocations with an eraser tester).

<Example 3> 30 parts of brilliant carmine 100 parts of the resin dispersion obtained in Production Example 3 70 parts of the resin dispersion obtained in Production Example 7 100 parts of kerosene were dispersed with a Keddy mill for 6 hours to obtain a concentrated toner having a viscosity of 23 cp. Then, 10 g thereof was dispersed in kerosene 1 to prepare a liquid developer for electrostatography, and a toner in which toner particles having an average particle diameter of 1.0 μm and 14 μm were mixed was obtained.

Next, using this developer, a copy was made on a zinc oxide photosensitive paper with a commercially available electrophotographic copying machine. As a result, a copy having an image fixability of 84.7% was obtained at an image density of 1.51. The primary fixing property (fixing property immediately after copying) was also good.

For comparison, the resin dispersion obtained in Production Example 1 was HO
With the developer prepared in the same manner except that STAFLON TF-9205 was used, the image density was 1.23 and the image fixing rate was as low as 73.1%.

The image fixing rate (%) was calculated from the formula of Y / X × 100 (X: image density before erasing, Y: image density of 5 reciprocations with an eraser tester).

<Example 4> Carbon black (Raven manufactured by Columbia Carbon Co., Ltd.)
14) 15 g 70 g of the resin dispersion obtained in Production Example 4 70 g of the resin dispersion obtained in Production Example 6 4 g of nickel naphthenate 100 g of kerosene was dispersed in a kedi mill for 6 hours to obtain a concentrated toner having a viscosity of 40 cp. 1 to prepare a liquid developer for electrophotography, and a toner in which toner particles having an average particle size of 0.9 μm and 26 μm were mixed was obtained.

Next, a copy was made on zinc oxide photosensitive paper using a commercially available electrophotographic copying machine using this developer, and a copy having an image density of 1.48 and an image fixing rate of 89.2% was obtained. The primary fixing property (fixing property immediately after copying) was also good.

For comparison, the resin dispersion obtained in Production Example 1 was HO
With the developer prepared in the same manner except that STAFLON TF-9205 was used, the image density was 1.06 and the image fixing rate was as low as 70.3%.

The image fixing rate (%) was calculated from the formula of Y / X × 100 (X: image density before erasing, Y: image density of 5 reciprocations with an eraser tester).

<Example 5> 15 g of phthalocyanine blue 100 g of the resin dispersion obtained in Production Example 1 70 g of the resin dispersion obtained in Production Example 6 3 g of nickel naphthenate 3 g of kerosene 100 g were dispersed in a kedi mill for 6 hours to obtain a concentrated toner having a viscosity of 38 cp. Then, 10 g thereof was dispersed in kerosene 1 to prepare a liquid developer for electrophotography, and a toner in which toner particles having an average particle size of 0.5 μm and 7 μm were mixed was obtained.

Next, a copy was made on a zinc oxide photosensitive paper using a commercially available electrophotographic copying machine using this developer, and a copy having an image density of 1.44 and an image fixing rate of 85.1% was obtained. The primary fixing property (fixing property immediately after copying) was also good.

For comparison, a developer prepared in the same manner except that the resin dispersion obtained in Production Example 1 was changed to Lubron L-5 had an image density of 1.14 and a low image fixing rate of 72.6%.

The image fixing rate (%) was calculated from the formula of Y / X × 100 (X: image density before erasing, Y: image density of 5 reciprocations with an eraser tester).

[Effect] According to the present invention, the dispersion stability of the toner is improved, the image density is improved, and particularly, the fixability immediately after copying is good.

Further, the copy paper obtained by using the developer of the present invention is excellent in water repellency and weather resistance even if it is exposed to weather, so that the damage is minimized.

──────────────────────────────────────────────────続 き Continuing on the front page (72) Kazuhiko Umemura 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Co., Ltd. (72) Inventor Hidemi Uematsu 1-3-6 Nakamagome, Ota-ku, Tokyo Ricoh Co., Ltd. (56) References JP-A-59-26743 (JP, A) JP-A-62-59967 (JP, A) JP-A-57-186760 (JP, A) JP-A-61-20056 ( JP, A) (58) Field surveyed (Int. Cl. ⁶ , DB name) G03G 9/12 321

Claims (1)

(57) [Claims] An aliphatic hydrocarbon and / or halogenated hydrocarbon liquid having a high insulating property and a low dielectric constant has an average particle size of 0.01 or less.
Small particle size group in the range of 1 to 1 μm and average particle size of 1 to 30
In an electrostatographic liquid developer obtained by dispersing toner particles having two particle size distribution peaks each composed of a group of large particle size particles, the particles constituting the large particle size group are represented by the following general formula: A liquid developer for electrophotography, comprising as a main component a copolymer of the monomer represented by (I) and fluoroacrylate and / or fluoromethacrylate. Here, in the formula, R ₁ is H or CH ₃ , and n is 1 to 4.