JPS6039228B2 - Liquid developer for electrostatography - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention particularly relates to a liquid developer for electrophotography which has excellent dispersion stability and fixing properties.

Typical liquid developers for electrostatic photography are mainly composed of carbon black, organic pigments or organic dyes, and synthetic or natural resins such as acrylic resins, phenol-modified alkyd resins, rosins, and synthetic rubbers. A toner to which a polarity control agent such as linseed oil or higher fatty acid has been added is dispersed in a carrier liquid made of a highly insulating, low electrolytic non-aqueous solvent such as a petroleum-based aliphatic hydrocarbon.

During the development process, such toner causes electrophoresis in accordance with the charge of the electrostatic port image formed on the surface layer of the electrophotographic photosensitive material or electrostatic recording material, and adheres to that area to form an image. However, in conventional liquid developers, the resin and polarity control agent diffuse into the carrier liquid over time, making the polarity unclear, resulting in a decrease in image density and fixability, an increase in background smearing, and other problems that make the image unclear. There was a drawback. Moreover, once the conventional toner aggregates, it is impossible to redisperse it, making it difficult to reuse it. Furthermore, due to these drawbacks, conventional liquid developers are unsuitable for offset printing, or for transfer such as charge transfer, pressure transfer, and magnetic transfer. The present invention eliminates the above-mentioned drawbacks, and provides a liquid developer for electrostatography that has excellent dispersion stability, fixing properties, and redispersibility, and can therefore be used not only for electrostatic photography, but also for offset printing and various transfer applications. This is what we provide.

- The present invention also provides a liquid developer for electrostatography that is easy to manufacture.

That is, the developer of the present invention contains a highly insulating, low dielectric constant aliphatic hydrocarbon and/or halogenated hydrocarbon carrier liquid, {1} a coloring agent, and (1) a general formula [where R is one day or -CH3 group]. , n is 6
an integer of 20 to 50 to 9 parts by weight; methyl methacrylate, hydroxyethyl methacrylate, isobutyl methacrylate, acrylic acid, which acts as an unsolvated component with respect to the carrier liquid; Polymerizing in an aliphatic hydrocarbon liquid 0.5 to 5 parts by weight of at least one monomer selected from the group consisting of monomers consisting of methacrylic acid, glycidyl methacrylate, and maleic acid. or a copolymer obtained by esterification with glycidyl methacrylate or methacrylic acid if necessary when the copolymer further contains methacrylic acid or glycidyl methacrylate in the liquid. Polymer, and (3) Softening point 60~
It is characterized by containing 130 qo of waxy substance or polyolefin dispersed therein.

To make such a developer, 50 to 9 parts by weight of the monomer represented by the above general formula and 0.5 to 5 parts by weight of the ethylenically unsaturated monomer are mixed with a petroleum-based aliphatic hydrocarbon. Or when polymerizing by heating in a small amount of a non-aqueous solvent with high chargeability and low electrolysis rate such as a halogen derivative thereof in the presence of a polymerization initiator such as azopisisobutyronitrile or penzoyl peroxide,
A softening point of 60 to 60 parts by weight of the resulting copolymer 95 to 6
13 pi○ waxy substance and/or polyolefin 5
-4 parts by weight may be added to the polymerization system and cooled after completion of polymerization.

The addition time may be before the polymerization, during the polymerization, or after the completion of the polymerization. Next, the non-aqueous resin dispersion thus obtained can be used as a concentrated toner for offset as it is, but if necessary, an appropriate amount of pigment, dye, or magnetic material is added and kneaded to make a concentrated toner. Dilute with carrier fluid. Methods for producing this type of non-aqueous resin dispersion have already been proposed in Japanese Patent Publications No. 40-19186 and Japanese Patent Publication No. 45-14545, but all of these methods have the disadvantage that the manufacturing process is especially complicated. was there. On the other hand, the method for producing the dispersion used in the present invention requires only one step, and is therefore much easier to produce than conventional methods. In the present invention, specific examples of monomers represented by the above general formula include stearyl acrylate, stearyl methacrylate, lauryl acrylate, lauryl methacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, cetyl acrylate, cetyl methacrylate,
Examples include octyl acrylate, octyl methacrylate, vinyl lauryl ether, vinyl stearyl ether, metavinyl stearyl ether, vinyl-2-ethylhexyl ether, and the like.

When these compounds are made into a copolymer, they become a solvating component of a nonaqueous solvent. Examples of ethylenically unsaturated monomers include methyl methacrylate, hydroxyethyl methacrylate,
At least one monomer selected from the group consisting of isobutyl methacrylate, acrylic acid, methacrylic acid, glycidyl methacrylate and maleic acid can be mentioned.

When made into a copolymer, these become unsolvated components of non-water soot. The above two-component copolymer has the unsolvated component as the core, and the solvated component is on the solvent side, and exists adsorbed on a wax-like substance or polyolefin in non-aqueous soot, and exhibits a strong fixing effect. It is.

It is thought that the solvated component of the copolymer has the effect of stably dispersing it in a non-aqueous solvent, and the non-solvated part of the copolymer becomes cloudy and has the function of adsorbing it to polyethylene and the like. As the non-aqueous solvent, petroleum-based aliphatic hydrocarbons or their halogen derivatives are used as described above.

Examples of such aliphatic hydrocarbons include n-hexane, n-bentane, isooctane, and indodecane.
Examples include Isopar L, Isopar E, and Shell Sol-71 manufactured by Shell Oil. Examples of halogen derivatives of aliphatic hydrocarbons include carbon tetrachloride and perfluoroethylene. Note that the above non-aqueous solvent has a condensation rate of 3 or less and a solubility parameter of 8.5 or less. Also, the softening point is 6
Specific examples of waxy substances or polyolefins having a weight of 0 to 130 qo are as follows.

Example of polyethylene Wax (Example of paraffin wax) These waxy substances or polyolefins have a specific gravity of 0.
．． 8 to 0.99, it is similar to aliphatic hydrocarbons which are dispersion media, and also has a molecular structure similar to aliphatic hydrocarbons, so it can significantly improve the dispersion stability of resins, pigments, magnetic substances, etc.

Furthermore, since the softening point is as low as 60 to 130° C., the toner can be fixed with slight heating. Furthermore, it also acts as an aggregation buffer, so even if the toner aggregates and its polarity changes, it can be redispersed and returned to its original polarity with a small amount of reconstitution. Examples of pigments or dyes include carbon black, oil flu, alkali blue, phthalocyanine flu, phthalocyanine green, spirit black, oil violet, benzidine yellow, methyl orange, brilliant carmine, fast red, and methyl violet.

As the magnetic material, conventionally known materials such as triiron tetroxide can be used. Examples of manufacturing the resin dispersion used in the present invention are shown below.

Production Example 1 In a four-necked flask equipped with a Tsuruhai machine, a condenser, a thermometer, and a dropping funnel and sealed with nitrogen, 100 g of n-hexane was placed and heated to 9 g.

Then stearyl methacrylate in this
60 tamethyl methacrylate 20 tamaleic acid 1M paraffin wax (softening point 8〆○) 30 taazobisisobutyronitrile The mixture was added dropwise over 2 hours, and further n-hexane 300 ml and triethylamine were added. 1.
09 was added and polymerization was continued by heating at 9 psi for 6 hours to obtain a resin dispersion with a polymerization rate of 96.8%.

Example 2 In the same flask as Production Example 1, add Isovar G 40M stearyl methacrylate 80 tacrylic acid
15 Glycidyl methacrylate
A mixed solution consisting of 10% AC polyethylene 6 & 6A (manufactured by Allied Chemical Co., Ltd.) and 25% azobisisobutyronitrile was added dropwise, and after heating at 90qC for 3 hours, further added 5% azobisisobutyronitrile, and heated to 90°C. When polymerization was carried out by continuing heating for 4 hours, a resin dispersion was obtained with a polymerization rate of 97%.

Production Example 3 In the same flask as in Production Example 1, add 100% isooctane, 2-ethylhexyl methacrylate, 70% isobutyl methacrylate, 30% tapolyethylene (Union force - DYNJ manufactured by Byde Co., Ltd. Softening point 10 is ○).
Add dropwise a mixture of 30 tAzobisisobutyronitrile and 10 tts, react for 3 hours at 95 ○, add 300 ts of isooctane and 5 ts of azopisisobutyronitrile, and further heat for 4 hours at 90 oo to polymerize. A resin dispersion was obtained with a yield of 97%.

Production Example 4 Into the same flask as in Production Example 1, a mixed solution consisting of 100 grams of lauryl methacrylate, 20 grams of taglycidyl methacrylate, and 3 grams of penzoyl peroxide was added.
After heating at ℃ for 2 hours, methacrylic acid for 10 hours, Sanwax 131-P (manufactured by Sanyo Chemical) for 40 hours, and penzoyl peroxide for 3 hours.
In the evening, Isopar L500 was added and heated for further 6 hours to obtain a low viscosity resin dispersion with a polymerization rate of 97.4%.

Production Example 5 In the same flask as in Production Example 1, add Shellzol 71 (manufactured by Shell Oil) 400 taglycidyl methacrylate 20 tacetyl methacrylate 80 thydroxyethyl methacrylate 10 tamaric acid
Add a mixed solution consisting of azobisisobutyronitrile for 10 minutes and react for 4 hours at 90 qo, then add ALATH.
Add ON-3 (polyethylene manufactured by DuPont) 409, 3 parts of azopisisobutyronitrile, and 0.1 part of pyridine,
The mixture was further reacted at the same temperature for 3 hours to obtain a low viscosity resin dispersion with a polymerization rate of 97.5%.

Production Example 6 In the same flask as in Production Example 1, add IOO talauryl methacrylate 80 talauryl methacrylic acid.
10 evening Penzoyl peroxide
A mixed solution of 1.8 hours was added thereto, and after reacting at 95°C for 6 hours, 5 nights of glycidyl methacrylate and 1 night of lauryl dimethylamine were added, followed by further reaction at the same temperature for 8 hours to esterify.

The degree of esterification was 30%. Then Isopar day 3
00 evening, add ALATHON-22 (polyethylene manufactured by DuPont) for 30 minutes and dissolve at 90 qo for 1 hour.
After cooling, a low viscosity resin dispersion was obtained with a polymerization rate of 99.4%.
Production Example 7 In the production of Production Example 2, the initial mixed solution was dropped into a flask and polymerized at 90 qo for 7 hours, resulting in a polymerization rate of 96.1.
% resin dispersion was obtained.

Production Example 8 In the production of Production Example 2, the initial azobisisobutyronitrile was used for 10 days, and polymerization was carried out in the same manner except that azobisisobutyronitrile was not added later, and the polymerization rate was 96.3%. A resin dispersion was obtained.

Production Example 9 In the production of Production Example 2, A
The prescription solution excluding C polyethylene 6 & mochi was dropped into a flask and polymerized at 90 oo for 7 hours. AC polyethylene 6 & 6A 25 oi was added to this, and after cooling, the polymerization rate was 9.
A 6.0% resin dispersion was obtained.

In addition, the above resin dispersion is heated at 5000, 2000 or 0°C.
Even after storage for one month, no development such as phase separation, sedimentation, or aggregation occurred. The features of the developer of the present invention are as follows.

1. Since the copolymer is adsorbed to the wax-like substance or polyolefin, there is little detachment of the copolymer during sewing, and therefore the dispersibility of the toner can be maintained stably for a long period of time.

Furthermore, even if aggregation occurs, it can be easily redispersed. Even if pigments, magnetic substances, etc. are included, dispersibility and
Good redispersibility. 2. Fixing performance (fixing rate) due to the mutual action of the copolymer and wax-like substance (or polyolefin)
is extremely good.

When pigments, magnetic substances, etc. are added, a large amount of resin is adsorbed to these particles, and therefore the fixing properties are good for the same reason. 3. Since the toner has excellent fixing properties and is lipophilic, it is possible to create an offset master with good ink adhesion.

4. Since the toner has excellent transferability (transfer rate to an object to be transferred), it can be effectively used in electrostatic transfer, pressure transfer, and magnetic transfer, and it is possible to form a transfer image with good fixability.

Examples are shown below.

Example 1 Resin dispersion liquid of Production Example 1 50 tamicrolith black (carbon black manufactured by Ciba Corporation)
10 ta isopar 11
A mixture consisting of I0O particles was dispersed for 5 hours using an attritor to form a concentrated toner, and the 18 particles were dispersed using an attritor for 5 hours.
It was diluted to make a liquid developer.

Next, an electrostatic port image was formed on a commercially available zinc oxide-resin dispersion electrophotographic copying paper by a conventional method, and then developed with the developer described above, resulting in an image with an image density of 1.30 and a fixation rate of 83%. It was done. Also, to check the stability of the toner, add 50% of the developer.
It was subjected to a forced deterioration test at 0°C for 30 days, but no change was observed. The retention rate is (5 on the clock meter)
It was determined from the formula xlooo/(initial image density) (image density after round trip erasing).

Example 2 Resin dispersion of Production Example 2 30% carbon black (MA-100 manufactured by Mitsubishi Carbon Co., Ltd.)
10.5 days
A mixture of IOO powder was dispersed in a ball mill for 4 hours to obtain a concentrated toner, and 20 millimeters of the mixture was diluted with Finpar G2 to prepare a liquid developer.

Next, a Seiryu latent image was formed on a commercially available wet-type electrophotographic copying paper for offset printing by a conventional method, and then developed with the above-mentioned developer, and then subjected to a fat-free treatment to obtain an offset master. When used for printing, the initial It showed a clearer finish than the printed matter. The ink was particularly easy to adhere to solid areas (long portions of the image) and line areas, and the finished density of the printed image agent was 1.25 or higher. Also, the toner image has good fixing properties (fixing rate 88%).
Therefore, offset printing of 10,000 mm or more was possible.

Example 3 Resin dispersion of Production Example 3 15
A mixed solution consisting of M triiron tetroxide, 109 isopar days, and IOO days was dispersed for 1 hour using an attritor to obtain a concentrated toner for magnetic transfer, and 12 times of the mixed solution was diluted with isopar G2 sleeves to prepare a liquid developer.

Next, after forming a static silkworm latent image on polyvinylcarbazole electrophotographic copying paper, it was developed with the developer, a transfer paper was placed on the image surface, and a magnetic field was applied from the transfer paper side to transfer the toner image. % was transferred onto the transfer paper. The fixation rate of the obtained transferred image was 85%. Example 4 Resin dispersion of Production Example 4 50% carbon black (Mitsubishi #44 manufactured by Mitsubishi Carbon Co., Ltd.)
Maya Microlith Flu (manufactured by Ciba)
52 isoper days 20
Disperse the mixed solution consisting of 0 ml in a ball mill for 24 hours,
A negative polarity concentrated toner for charge transfer was used, and a liquid developer was prepared by diluting 10 days of it with 2 days of isopar.

Next, a static haze latent image was formed on a commercially available electrophotographic copying paper for charge transfer, and after being developed with the developer, charge transfer was performed on transfer paper.
A transferred image with excellent contrast was obtained. In order to check the storage stability of the developer, a forced deterioration test was conducted at 50 qo for 3 months, but the developer after the test was unchanged from its initial state. Example 5 A mixed solution of the resin dispersion of Production Example 5, consisting of 50 units of isoper and 180 units of dispersion, was dispersed for 30 minutes in a homomixer to obtain a concentrated toner for offset masters, and the 25 units were diluted with two sleeves of isoper per day to form a liquid developer. I got it.

Printing was then performed using an offset master prepared in the same manner as in Example 2, and as in Example 2, printed matter with good contrast was obtained. Developing solutions for Examples 6, 7, and 8 were prepared in the same manner as in Example 2, except that the resin dispersions were changed to Production Examples 7, 8, and 9, respectively. The toner particle size of each of these developers was 0.35 to 0.40, and the characteristics were as shown in Table 1. Table -
1 Comparative Examples 1-2 Resin Composition 1 100 g of n-hexane was placed in a four-ring flask, heated to 980 ℃, and stearyl methacrylate was added to this.
60 methyl methacrylate 20 tamaleic acid 10 paraffin wax 30 tazobisisobutyronitrile 2 The above mixture was added dropwise for 2 hours.

Furthermore, n-hexane 300 times, triethylamine 1.0 times, glycidyl methacrylate 10 times, hydroquinone 0 times
．． The reaction was carried out for 1 hour at 90oo. To this resin dispersion, 200 g of n-hexane, 50 g of methyl methacrylate, and 2 g of azobisisobutyronitrile were added dropwise for 1 hour, and the graft reaction was further carried out at 90 qo for 2 hours to form a dispersion of the graft polymer. Obtained. The polymerization rate was 97%. Resin composition 2 100 g of toluene was placed in a four-round flask and heated to 95°C, and stearyl methacrylate was added to this to 60 g of toluene.
The above strained mixture was added dropwise for 2 hours to polymerize.

Furthermore, 200 ml of toluene and 1.0 ml of tatriethylamine were added, and polymerization was continued for 6 hours at 90 ml to obtain a resin solution with a polymerization rate of 98.2%. A developer was prepared by mixing 100% of the above resin composition and 30% of carbon black with Scherzol 71200 and dispersing it in a ball mill for 4 hours. Each developer was subjected to a forced deterioration test for 60 days at 50:00. After application, the electrostatic latent image was developed and its characteristics were investigated.

The results were as shown in Table-2. Table 2 From these results, it can be seen that the developer of Comparative Example 1, which used a resin having a graph part as the resin used in the developer of the present invention, had a poor fixing rate, and the resin polymerized in an aromatic solvent such as toluene had a poor fixation rate. The developer of Comparative Example 2 using the above had a poor transfer rate and a low image density.

Claims (1)

[Scope of Claims] 1. In a highly insulating and low dielectric constant aliphatic hydrocarbon and/or halogenated hydrocarbon carrier liquid, (1) a coloring agent, (2) a general formula, a mathematical formula, a chemical formula, a table, etc. ▼ 50 to 90 parts by weight of monomer (a) represented by [where R is -H or -CH_3 group, n is an integer of 6 to 20] and acts as an unsolvated component with respect to the carrier liquid. , methyl methacrylate, hydroxyethyl methacrylate, isobutyl methacrylate, acrylic acid, methacrylic acid, glycidyl methacrylate, and maleic acid (b) 0.5 to 50 parts by weight in an aliphatic hydrocarbon liquid, or if the copolymer further contains methacrylic acid or glycidyl methacrylate in the liquid, if necessary, glycidyl A liquid developer for electrostatic photography, characterized in that it contains a copolymer obtained by esterification with methacrylate or methacrylic acid, and (3) a wax-like substance or polyolefin having a softening point of 60 to 130°C dispersed therein.