JPS6039229B2 - Liquid developer for electrostatography - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a liquid developer for electrophotography, and more particularly, a liquid developer for electrophotography in which a flashed colorant and a resin dispersion composition as main components are dispersed in a non-aqueous solvent. Regarding.

General liquid developers for electrostatic photography are mainly composed of pigments such as carbon black, and synthetic or natural resins such as acrylic resins, phenol-modified alkyd resins, rosins, and synthetic rubbers. A toner containing a gutter control agent such as a fatty acid is dispersed in a carrier made of a non-aqueous solvent with high insulation properties and low induction, 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.
Furthermore, the pigment causes strong secondary aggregation and cannot be easily dispersed into primary particles even with ordinary equipment such as a ball mill, attritor, or ultrasonic waves, so the pigment is exposed on the surface of the toner particles and the proper controllability is reduced between each particle. When using the toner for transfer such as offset printing, pressure transfer, electrostatic transfer, magnetic transfer, etc., due to the possibility of variations in the toner transfer material, especially highly smooth transfer paper or paper with low oil absorption. The transfer rate was low.

In addition, conventional developers have poor primary fixing properties and have the disadvantage that toner sticks to your hands when you touch the copy paper immediately after copying, and furthermore, they have poor dispersion stability, resulting in unsatisfactory storage stability and durability. The present invention provides an electrostatographic liquid developer which eliminates the above-mentioned drawbacks, and which has improved transfer rate, storage stability, durability, etc.

That is, the present invention disperses a flashed colorant as a main component, a copolymer prepared by a specific manufacturing method, and a waxy substance with a softening point of 60 to 13,000 in a nonaqueous solvent with high insulation and low dielectric constant. This is what I did.

The colorant to be dispersed in the non-aqueous solvent is one that has been subjected to flashing treatment. Flushed colorants are produced using a water-containing pigment cake, and are finely divided pigments coated with a resin that is substantially insoluble (key-soluble or insoluble) in the carrier liquid that makes up the developer solution. For example, a water-containing cake consisting of a water-containing paste of an organic pigment and carbon black is kneaded with a solution of a substantially impregnable resin in a developer carrier liquid, and the water surrounding the organic pigment and carbon black is mixed with the resin. After displacement with a solution, water and solvent are removed, and the product is obtained by pulverization. The water-containing pigment paste may be a pigment paste obtained by producing a pigment and filtering water using a filter, or a paste obtained by impregnating a non-aqueous pigment with water, which can be used as it is. As the pigment, inorganic pigments such as carbon black or organic pigments shown below can be appropriately used. Examples of organic pigments include Phthalocyanine Flu, Phthalocyanine Green, Sky Blue, Rhodamine Lake, Malachite Green Lake, Methyl Violet Lake, Peacock Blue Lake, Naphthol Green B, Naphthol Green Y, Naphthol Yellow S, Lysol First Yellow 20, Permanent Red 4R, Brilliant Fast Scarlet, Hanser Yellow, Benzidine Yellow, Resole Red, Lake Red C, Lake Red D, Brilliant Carmine aB, Permanent Red F9R, Pigment Scarlet Cord, Bordeaux 1 Fertilizer, etc. are used. The carbon black used in the present invention can be furnace black, acetylene black, channel black, etc. Commercially available products include Printex G,
Subethical Black 15, Subécial Black 4, Subécial Black 4-B (manufactured by Degussa), Mitsubishi #44
, #30, MA-11, MA-100 (manufactured by Mitsubishi Carbon Corporation), Raven 30, 40, Condatex SC (
(manufactured by Kyabot Corporation) are known. The mixing ratio of the organic pigment and carbon black is preferably 1:2 to 20 by weight; if the ratio of the organic pigment is less than the above-mentioned value, the gutter properties of the toner will be insufficiently controlled, and if it is more than the above-mentioned value, the color tone of the image will be affected. The color deviates from black, which is inconvenient as a copy image for office use.

The water-containing cake of carbon black and organic pigment is placed in a kneader called a flasher together with a resin solution and mixed well. As a result, the water present in the carbon black and organic pigment surroundings is replaced by the resin solution. Thereafter, the solvent is removed to obtain a mass which is ground into a fine powder of flushed colorant. Resins used during flushing treatment include natural resin-modified carbonic acid resin, natural resin-modified maleic acid resin, dammar copal, shellac,
Resins that are insoluble in aliphatic hydrocarbons, which are carrier liquids of liquid developers, such as gum rosin, hardened rosin, ester gum glycerin ester-modified maleic acid resin, styrene-butadiene copolymer, or vinyltoluene-butadiene copolymer. is preferred. The amount of resin used is preferably 1 to 4 parts by weight per 1 part by weight of the total weight of carbon black and organic pigment. Also, when flushing, add 1 part by weight of the polymerizable monomer to 1 part by weight of the total weight of carbon black and organic pigment.
It is also possible to add 0.1 parts by weight of ×10-3 to 0.1 parts by weight together with a polymerization initiator to polymerize the monomer during the flushing process. It may also be controlled by combining.

Such monomers are preferably those having a polarity controlling effect, such as unsaturated carboxylic acids such as acrylic acid, methacrylic acid, fumaric acid, itaconic acid, crotonic acid, and maleic acid, and 2-hydroxyethyl acrylate, 2-hydroxyethyl acrylate, and 2-hydroxyethyl acrylate. -Hydroxyethyl methacrylate, 2-hydroxyethylpropyl acrylate, 2-hydroxypropyl methacrylate, glycidyl acrylate, glycidyl methacrylate, styrene, vinyl acetate, acrylonitrile,
Examples include vinyl monomers such as methacrylonitrile, acrylamide, methacrylamide, and N-vinylpyrrolidone.

The flushed colorant fine powder obtained as described above is in the form of fine particles in which carbon black and organic pigment are coated with resin in the state of primary particles, and when used in toner, the organic pigment is Direct exposure to the surface of toner particles can be prevented.

The above copolymer used in the present invention has the general formula [
Here, R is day or -CH3 group, n is an integer from 6 to 20]
and methyl methacrylate, hydroxyethyl methacrylate, acrylic acid, which acts as a non-sooting component for the carrier liquid, and 50 to 9 parts by weight of a monomer represented by
Obtained by 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 an English polymer obtained by esterifying with glycidyl methacrylate or methacrylic acid if necessary when the copolymer further contains methacrylic acid or glycidyl methacrylate in the liquid. It is.

Specific examples of the monomer represented by the above general formula include stearyl acrylate, stearyl methacrylate, lauryl acrylate, lauryl methacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, hexyl acrylate, hexyl methacrylate, cetyl methacrylate, and octyl methacrylate. ,
Examples include stearyl vinyl ether.

Specific examples of monomers include methyl methacrylate, hydroxyethyl methacrylate, acrylic acid,
Mention may be made of methacrylic acid, maleic acid and glycidyl methacrylate.

A mixture of these monomers (i) and monomer (rho) and a polymerization initiator such as azobisisobutyronitrile or penzoyl peroxide is added to the mixture to form an aliphatic hydrocarbon and/or halogenated hydrocarbon liquid. It has excellent long-term dispersion stability when made into a liquid developer by polymerizing it dropwise into a liquid developer, or by polymerizing it by mixing monomer {a}, monomer ``l'' and a polymerization initiator with the above solvent. Become something. Furthermore, in the present invention, in order to improve the dispersibility of the toner, the monomer mixture, during the polymerization process, or after the completion of the polymerization, has a softening point of 6.
A waxy substance or polyolefin at a temperature of 0 to 130° C. is added, heated and dissolved, and then cooled.

Examples of the aliphatic hydrocarbon liquid include n-hexane, n-bentane, i-octane, and i-dodecane, and examples of the halogenated hydrocarbon include carbon tetrachloride and perfluoroethylene. Further, specific examples of the waxy substance or polyolefin having a softening point of 60 to 130°C in the present invention are as follows.

Example of wax (paraffin wax) Product name Softening point 0) Junsei Kagaku Paraffin wax 60-98 Kobayashi Kako Sarashi Beeswax 65 Cetanol 80 Nagai Kako Sarashi Beeswax 65 Steel Chemical Frozen 110 Softening point is 60-130q When the waxy substance or polyolefin of ○ is used in combination with the polymer of the present invention described above, the waxy substance or polyolefin precipitates into fine particles in the polymerization system by rapid cooling and is dispersed in the solvated copolymer. As a result, the dispersion effect as a developer can be enhanced.

The weight ratio of the copolymer to the waxy substance or polyolefin is 5 to 40 parts by weight to 50 to 9 parts by weight of the copolymer.
If the weight ratio of the wax-like substance or polyolefin to the copolymer is less than 5 parts by weight, the image density and fixing properties will be low, and if it is more than 4 parts by weight, the toner particle size will increase and the image will become sharper. Punes gets worse. The non-aqueous solvent for dispersing the flushed colorant and the resin dispersion composition (consisting of a copolymer prepared by a specific manufacturing method and a waxy substance with a softening point of 60 to 130 qo as described above) is a high-temperature solvent. Insulating, low dielectric constant, n-hexane, n
-Aliphatic hydrocarbons such as pentane, indodecane, and isooctane (commercially available products manufactured by Exon, Isopa-Ni, Iso/Guichi G, Iso/Guichi L, Iso/Guichi E, Shell Oil Co., Ltd., Shell Sol 71) etc.

) and halogenated hydrocarbons such as carbon tetrachloride and perchlorethylene. Although the resin dispersion composition is obtained as a resin dispersion liquid polymerized in a non-aqueous solvent, the non-aqueous particles in the molten developer and the non-aqueous solvent used during polymerization do not necessarily have to be the same. The colorant flushed as described above is coated with resin in the state of primary particles,
In addition, resin dispersion compositions generally have small particle sizes, and have good dispersion stability and
Because it has excellent polarity control and adhesive properties, liquid developers made by dispersing these components are dispersed with toner particle sizes adjusted to about 0.3 to 0.5 mm. There is. ■
It has poor smoothness and can be easily transferred to paper with low oil absorption. It has many advantages, such as improved adhesive storage stability and durability, and the ability to make more than 30,000 copies per year.
The colorants used in the electrostatic photographic liquid developer are as follows.

Colorant A Water 500 Printex G 30 Tarkali Blue
After thoroughly kneading with a 20 tuff flasher, 600 m of Betsukasite P-720 (10% toluene solution) was added to the flasher and further kneaded.

Next, heat and reduce pressure to remove water and solvent to reduce water content to 0.
A mass of 92% colorant was obtained. This was ground in a stone mill to obtain a powder of 0.1 to 0.2 mm. Colorant B Water 560 Yen Carbon MA
25 minutes was thoroughly heated in a flasher, and 700 degrees of shellac (10% butanol solution), 5 degrees of methacrylic acid, and 0.1 degrees of azobisisobutyronitrile were added thereto, and the mixture was kept at 15,000 degrees and mixed for 4 hours. I made it bran.

Next, the solvent was removed together with the remaining moisture by heating and vacuum to obtain a mass of colorant with a moisture content of 0.80%. This was ground in a hammer mill to obtain a colorant powder of 0.1 to 0.3 mm. Colorants C to P Colorants were prepared in the same manner as in the preparation of Colorant A, except that the raw materials were changed.

Table 1 Next, the resin dispersion compositions used in the electrostatic photographic liquid developer are as follows.

Resin dispersion composition A, equipped with a condenser, thermometer, and dripping load, N
- Add n-hexane 10 to the sealed Yotsuro flask.
09 and heated it to 95C0.

Next, add the following mixture to stearyl methacrylate.
60 methyl methacrylate 2
0 tamaleic acid 100% paraffin wax (softening point 8.0) 300% azobisisobutyronitrile 200% dropped into a flask for 2 hours to polymerize, and further added n-hexane 300% and triethylamine 1.00%.
When polymerization was carried out at 90q○ for 6 hours with addition of
．． An 8% resin dispersion was obtained.

Resin dispersion composition B Isopar G 400 Tastearyl methacrylate 809 Acrylic acid
15 glycidyl methacrylate 10 t AC polyethylene 6&M (manufactured by Allied Chemical Co., Ltd.) 25 ts azobisisobutyronitrile 5 t was added and polymerized for 4 hours at 9,000 ℃ to obtain a resin dispersion with a polymerization rate of 97%.

Resin dispersion composition C isooctane 100/2-
Ethylhexyl methacrylate 70 Tysobutyl methacrylate 30 Tapolyethylene (DYNJ softening point 1020 manufactured by Union Carbide)
30 Tazobisisobutyronitrile 10
The above mixture was dropped into a flask and polymerized at 960°C for 3 hours, then 300ml of isooctane and 5x of azobisisobutyronitrile were added and polymerized for another 4 hours to obtain a resin dispersion with a polymerization rate of 98.5%. Ta.

Resin dispersion composition D lauryl methacrylate 100 taglycidyl methacrylate 20 polypenzoyl peroxide
39 After polymerizing the above mixed solution at 9000 for 2 hours, methacrylic acid was added for 10 minutes, and Sunwax 131-
P (manufactured by Sanyo Chemical Co., Ltd.) for 40 hours, Penzoyl peroxide for 3 hours, and Isopar L for 500 hours were added, and polymerization was further carried out for 6 hours.

As a result, the polymerization rate was 97.4%, and the viscosity of 2000 was 3.
A resin dispersion with extremely low viscosity and P was obtained. Resin dispersion composition E Shellsol 71 (manufactured by Shell Petroleum) 400 taglycidyl methacrylate 20 polycetyl methacrylate 80 hydroxyethyl methacrylate 10 tamaric acid
After reacting the above mixture at 90°C for 4 hours with 5 tA of azobisisobutyronitrile for 10 days, ALATHON-3 (manufactured by DuPont, polyethylene) 4
0 night, azobisisobutyronitrile 3 nights, pyridine 0.
After 1 night of polymerization and further polymerization for 3 hours, the polymerization rate was 97.
．． A resin dispersion of 5%, viscosity of 20q0, and 34CP was obtained.

Resin dispersion composition F Isoper day IOO talauryl methacrylate 80 talauryl methacrylic acid
10 evening Penzoyl peroxide
After polymerizing for 6 hours at 1.8 pm at 95 pm, glycidyl methacrylate for 5 nights, azobisisobutyronitrile for 3 nights, and lauryl dimethylamine for 1 night were added and polymerized for further 8 hours. Co., Ltd., polyethylene) for 30 minutes, melted at 9,000 for 1 hour, and then cooled to obtain a polymerization rate of 99.4% and a viscosity of about 4 P (20
A resin dispersion liquid was prepared.

The flushed colorant and resin dispersion composition (prepared as a dispersion) as described above were dispersed in a non-aqueous dispersion as shown in Table 2 to prepare a liquid developer for electrostatography of the present invention.

Resin Dispersion Composition G In the production of resin dispersion composition B, the initial mixed solution was dropped into a flask and polymerized at 90°C for 7 hours to obtain a resin dispersion with a polymerization rate of 96.1%.

Resin dispersion composition (1) In the production of resin dispersion composition B, the initial azobisisobutyronitrile was used for 10 minutes, and polymerization was carried out in the same manner except that azobisisobutyronitrile was not added later. A 96.3% resin dispersion was obtained.

Resin dispersion composition I In the production of resin dispersion composition B, AC
The formulation solution excluding polyethylene 6 and solution was dropped into a flask and polymerized at 90 qo for 7 hours.
After adding 25% of water and cooling, the polymerization rate was 96.
A 0% resin dispersion was obtained.

Table 2 Developer solutions of Examples 7, 8 and 9 were prepared in the same manner as in Example 2, except that the resin dispersion compositions were replaced with resin dispersion compositions G, 1 and 1, respectively.

The toner particle size of each of these developers was 0.35 to 0.40. Next, the characteristics of the developing solutions of Examples 1 to 9 were measured, and the results were as shown in Table 3.

Table 3 Primary fixing property: 20°C - 65% RH, time until toner no longer sticks to hand when rubbed by hand every 10 seconds after copying Transfer rate: Transferred toner xloo (%)
Toner on the drum Comparative Example Resin Composition J 100ml of n-hexane was placed in a four-sided flask and heated to 95°C, and stearyl methacrylate was added to it.
60 methyl methacrylate 20 tamaleic acid 10 paraffin wax 30 tazobisisobutyronitrile The above mixture was added dropwise for 2 hours to polymerize.

Furthermore, n-hexane 300 times, triethylamine 1.0 times, glycidyl methacrylate 10 times, hydroquinone 0 times.
．． The mixture was added overnight and reacted at 90°C for one period. 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 for 2 hours at 90 qo to obtain a dispersion of the graft polymer. Ta. The polymerization rate was 97%.
Resin Composition K: 100 quarts of toluene was placed in a quart flask, heated to 95 quarts, and stearyl methacrylate was added to this.
0 methyl methacrylate 20 tamaleic acid 10 azobisisobutyronitrile The above mixture was added dropwise for 2 hours to polymerize.

Further, 200 ml of toluene and 1.0 ml of triethylamine were added, and polymerization was continued at 9,000 ℃ for 6 hours to obtain a resin solution with a polymerization rate of 98.2%. The above resin composition 100% and colorant A50
A developing solution was prepared by mixing Schersol 71200 and dispersing it in a ball mill for 4 hours, and the same test as in the above example was conducted.

The results were as shown in Table-4. Table 4 From these results, it can be seen that the developer prepared by using Resin J, which has a graph part in addition to the resin used in the developer of the present invention, had poor primary fixing properties and was polymerized in an aromatic solvent such as toluene. Resin K
The developer using this has poor transferability.

Furthermore, the screen power when developing using both comparative developers is as follows.
This is inferior to 7 to 9 lines/skin in this example.

Claims (1)

[Claims] 1. In a highly insulating and low dielectric constant aliphatic hydrocarbon and/or halogenated hydrocarbon carrier liquid, (1) a flushing-treated colorant, (2) general formula▲mathematical formula, chemical formula , tables, etc. ▼ 50 to 90 parts by weight of the monomer (a) represented by [here, R is -H or -CH_3 group, and n is an integer of 6 to 20] and an insolvent to the carrier liquid. at least one monomer selected from the group consisting of monomers consisting of methyl methacrylate, hydroxyethyl methacrylate, acrylic acid, methacrylic acid, glycidyl methacrylate, and maleic acid, which acts as a sum component (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. A liquid developer for electrostatic photography, characterized in that it contains a copolymer obtained by esterification with glycidyl methacrylate or methacrylic acid, and (3) a wax-like substance or polyolefin having a softening point of 60 to 130°C dispersed therein. .