JPS61277968A - Liquid developer - Google Patents

Abstract

PURPOSE:To stabilize an electric charge of a carrier liquid by incorporating at least copolymer of a pigment particle contg. a halogen atom, a cyclic gum, a monomer soluble to the carrier liquid and an ethylenical unsatd. compd. contg. a halogen atom or a hydroxy group into the carrier liquid. CONSTITUTION:The monomer soluble to the carrier liquid and the monomer insoluble to the carrier liquid are copolymerized with a resin capable of giving a fixing property to the titled developer. Preferably, the carrier liquid has >=10<9>OMEGAcm the electric resistance and <=3 the permittivity. The resin soluble to the carrier liquid which serves to give a dispersion stability and a fixing property to the title agent is comprised a higher alkylate of an acrylic acid or a methacrylic acid. The halogen contg. resin which serves to give a negative electrocharge and a grain property to the title agent is composed of halogenated olefins such as a dichlorobutent or a trichloropropene. Thus as the toner having a negative polarity, a uniform particle size and a high dispersion stability is obtd. the photosensitive body or the electrostatic recording body having a positive polarity may be developed according to an electrostatic latent image.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a liquid developer for visualizing electrostatic latent images obtained by electrophotography, electrostatic recording, or the like.

[Prior art to the invention]

The image developed by liquid developer has the following characteristics: ■ High resolution due to the small toner particle size, ■ Easy development of low contrast latent images, ■ Excellent gradation reproducibility, ■ It is very useful in fields where images that are easy to maintain are required, such as offset printing plates and the production of microfilms by electrophotography.

Conventionally, liquid developers used to visualize electrostatic latent images in electrophotography or electrostatic recording have been made by mixing pigments such as carbon black and resins that provide dispersibility and fixing properties such as alkyd resins with alicyclic hydrocarbons. etc., using a dispersing machine such as a ball mill. However, such liquid developers tend to aggregate or settle when left for a long time.
It is difficult to re-disperse toner that has aggregated or settled, and even if it is re-dispersed using a powerful mechanical dispersion method, there are problems such as a decrease in developing ability and deterioration of fixing properties. Ta.

In addition, Special Publication No. 44-19196 and Special Publication No. 50-1
In order to solve these drawbacks, Japanese Patent No. 7262 describes a developer that is directly grafted onto a pigment, but there are limitations to the pigment.

[Purpose of the invention]

An object of the present invention is to provide a liquid developer in which pigment particles are dispersed in a carrier liquid, which exhibits negative chargeability and has excellent charge stability, and in particular has little agglomeration or sedimentation even when left for a long time. It is an object of the present invention to provide a liquid developer whose initial characteristics can be reproduced by simple redispersion by stirring even if such a developer occurs, and whose developing ability is less deteriorated.

Still another object is to provide a liquid developer for electrophotography that provides developed images with good oil sensitivity when used as an offset printing plate.

Still another object is to provide a liquid developer for electrophotography that allows the developed image to be easily inspected with the naked eye even on a deep blue photosensitive plate such as a copper phthalocyanine-resin dispersion system.

[Summary of the invention]

That is, the present invention provides a liquid developer in which pigment particles imparting charge polarity and resin imparting fixing properties are dispersed in a carrier liquid, in which a monomer that is soluble in the carrier liquid and a monomer that is insoluble in the carrier liquid are dispersed. It is a liquid developer characterized by being copolymerized with the resin that imparts fixing properties, and is used for reversal development of negatively charged latent images, for example, for microfilm reader printers, or for line printers using CRT exposure. It can also be used for positive development of positively charged latent images, for example, for PPC or CPC electrophotographic systems using P-type photoconductors such as amorphous selenium, polyvinylcarbazole, and copper phthalocyanine resins. be able to. In particular, it is useful for developing offset printing plates using semiconductor laser exposure using copper phthalocyanine as an electrophotographic photoreceptor, as described in Japanese Patent Application No. 57-225959, which belongs to the latter category.

[Detailed description of the invention]

The present invention will be explained in detail below.

The carrier liquid constituting the present invention has an electrical resistance of 1109
It is desirable that the dielectric constant is hC or more and the dielectric constant is 3 or less. For example, aliphatic hydrocarbons, alicyclic hydrocarbons, aromatic hydrocarbons, halogenated hydrocarbons, etc. can be used, but imparaffinic petroleum solvents are preferred in terms of odor and toxicity. Specific examples include Shell Silua 1 (manufactured by Shell Kagaku Co., Ltd.), Isopar G, Isopar H, Isopar L (all manufactured by Esso Standard Co., Ltd.), and the like.

The pigment particles used in the present invention contain halogen atoms in the pigment molecules. For example, C1■, Pigment Yellow 2 (C,1,11730), C2■2 Pigment Yellow (C,1,11710), C,I Pigment Yellow 6 (C,1,11670), C,1, Pigment Yellow 10 (C, 1, 12710), C, I
.

Pig 17 Toy r-CI-12rC, I, 21090)
, C0■, Pigment Yellow 12 (C, 1, 2109
0), Irugalan Yellow 2GL, and the like.

Cyclized rubber controls fixing properties and printing durability, and is a resinous material obtained by isomerizing raw rubber by dissolving it in petroleum distillate and treating it with tin tetrachloride, titanium tetrachloride, etc., and is a polymer of natural rubber. It has a structure in which the chain is partially circularized. Furthermore, cyclized rubber obtained by cyclizing synthetic polyimprene can also be used. Specific examples include Thermolite-N, -P, -3 (
(manufactured by Seiko Kagaku Co., Ltd.), NR-50 (manufactured by Gutdeyer Co., Ltd.)
Among them, those having a Stokes coefficient of 3.0 to 6.0 and a softening point of 40°C to 60°C are particularly desirable. Can be copolymerized with esters of methacrylic acid or acrylic acid.
It is thought that this is added to the double bond of the cyclized portion or the double bond of the polyisoprene structure portion that remains uncyclized.

Examples of resins soluble in the carrier liquid that control dispersion stability and fixing properties include polymers of methacrylic acid or higher alkyl (eg, lauryl, tridecyl, 2-ethylhexyl, stearyl, etc.) esters of acrylic acid. Further, although these monomers can be used alone, a copolymer of two or more monomers can also be used. Furthermore, it is also possible to copolymerize compounds that are insoluble in the carrier liquid when polymerized alone. However, this content is 30%
The following are preferred. Examples of compounds that become insoluble include glycidyl methacrylate and lower alkyl (eg, methyl, ethyl, hydroxyethyl, etc.) esters of methacrylic acid or acrylic acid.

Resins containing halogens that control negative chargeability and particle properties include halogenated olefins such as dichlorobutene and trichloropropene, 2-chloro-113-butadiene, 2-bromo-1,3-butadiene, and 2-iodo- 1
, 3-butadiene iodine halogenated dienes, vinyl fluoride, vinylidene fluoride, chlorotrifluoroethylene, tetrachloroethylene, vinyl chloride, vinylidene chloride, vinyl bromide, vinylidene bromide, vinyl iodide, and other vinyl halides. , 0-fluorostyrene, m-fluorostyrene, p-fluorostyrene, -chlorostyrene, 0-chlorostyrene, m-chlorostyrene, p-
Chlorostyrene, 2,5-dichlorostyrene, 2,3-
Dichlorostyrene, 2,4-dichlorostyrene, 2+6
-cyclostyrene L/7.3.4-dichloroethylene,
3.5-dichlorostyrene, 0-7” lomostyrene, m
-7" Halogenated styrenes such as lomostyrene, p-bromostyrene, m-iodostyrene; unahalogenated vinyl esters such as vinyl trifluoroacetate, vinyl chloroacetate, and vinyl dichloroacetate; Examples include acrylic acid or methacrylic esters having a halogenated alkyl group, such as biru acrylate, d-chloromethyl acrylate, C<-chloroethyl acrylate, and β-chloroethyl methacrylate.Among these, those with high reactivity , acrylic acid or methacrylic acid esters having a halogenated alkyl group are preferred because their boiling point is not too low, making it easy to react in liquid, and copolymerization is easy.Especially when the alkyl group has 4 or less carbon atoms and 1 Preferably, at least one -H group is substituted with a halogen group.

Furthermore, in order to obtain a developed image that has high smoothness, is not disturbed by the aperture roll even when developing a non-porous photoreceptor, and has excellent film adhesion, halogen-containing resin is used in acrylic acid. or 1 carbon number of methacrylic acid
~4 alkyl esters, at least one of the alkyl groups
Compounds in which each -H is replaced with a halogen and an 10H group are preferred. These compounds include 4-chloro-3
-Rhodanized hydroxyolefins represented by hydroxybutene 2-bromo 3-hydroxy-1,3-
Halogenated hydroxy dienes represented by butadiene, halogenated hydroxy styrenes represented by 0-chloro-P-hydroxystyrene, 2,6-dipromo-4-hydroxystyrene, 3-chloro-2-hydroxypropyl methacrylate, 3 -Butyl-2-hydroxypropyl acrylate and 2-chloro-1-hydroxyethyl methacrylate are examples of acrylic acid or methacrylic acid esters having a halogenated hydroxyalkyl group. Among these, acrylic acid or methacrylic acid esters having a halogenated hydroxyalkyl group are used because they have high reactivity, are easy to react in liquid because their boiling point is not too low, and are easy to copolymerize. preferable.

Particularly preferred are alkyl esters of acrylic acid or methacrylic acid having 1 to 4 carbon atoms in which the -H of the alkyl group is replaced with at least one halogen and 10H group.

Furthermore, the developer of the present invention may contain, for example, lecithin, calcium petroleum sulfonate, calcium alkylbenzene sulfonate, sodium dioctyl sulfonate,
Charge control agents such as alkylalanine, calcium alkylnaphthalene sulfonate, and di-2-ethylhexyl sodium sulfosuccinate can be added.

When using the developer of the present invention, a concentration of 0.1 to 10.0% by weight of non-drying components is suitable, as too high a concentration will cause background fog, and too low a concentration will result in a decrease in image density. , preferably 0.3 to 3 weight percent.

The structure of the present invention has been described in detail above, and then a method for producing a developer will be described.

The developer of the present invention is produced by firstly graft-polymerizing a resin soluble in a carrier liquid with a pigment and cyclized rubber dispersed in the carrier liquid, and then polymerizing a halogen-containing resin. A method in which a pigment and a cyclized rubber are polymerized in a solvent that dissolves both a carrier liquid-soluble resin and a halogen-containing resin, then a carrier liquid is added, and the solvent is further removed by vacuum distillation or the like. , and thirdly, polymerize in the solvent, then dry and remove the solvent and evaporate.

Furthermore, a method of redispersing in a carrier liquid, etc. can be used. In the first method, since the cyclized rubber has good dispersibility in the carrier liquid, it is easy to uniformly polymerize the composition that is soluble in the carrier liquid, and the halogen-containing resin is insoluble in the carrier liquid. As this composition undergoes addition polymerization to a polymer of cyclized rubber and soluble resin, particles are formed. In the second method, since all three components are soluble in the reaction solvent, they are uniformly soluble even after polymerization 1-1. Adding the carrier solvent with stirring results in
Emulsify and granulate.

When the solvent is removed by vacuum distillation or the like, the solvent is replaced with a carrier liquid. In this case, it is necessary that the carrier liquid and the reaction solvent are compatible. In the third method, compatibility is not required, but mechanical dispersion such as a shaking dispersion method is required during redissolution.

The reaction solvent is not particularly limited, and common solvents such as aromatic hydrocarbons such as toluene, ketones such as acetone, and tetrahydrofuran can be used. During polymerization, addition of a polymerization initiator such as azobisisobutyronitrile or benzoyl peroxide and heating at 60°C to 100°C are applied, and it is preferable that the polymerization is performed in an oxygen-free atmosphere. A developer is prepared by diluting the thus obtained dispersion with a carrier liquid.

[Operation of the present invention]

As described above, in the liquid developer of the present invention, pigment particles containing halogen atoms are dispersed in a fixing resin and then dispersed in a carrier liquid. It is created by polymerization and block polymerization, adding an ethylenically unsaturated compound containing a halogen group or hydroxyl group, and graft polymerization and block polymerization (second step).The effects are explained in the order of the steps.
The first step has the effect of causing the fixing resin to adhere to the surface of the pigment particles.

The fixing resin needs to dissolve or swell in the carrier liquid, but it has been confirmed that the fixing resin cannot be removed 100% from the pigment particles after the first step, no matter how dilute the dispersion.

In the second step, a soluble monomer is added to the carrier liquid and polymerized, so graft polymerization occurs with the fixing resin, which prevents the fixing resins from coagulating together. Alternatively, in order to polymerize an ethylenically unsaturated compound containing a hydroxyl group, graft polymerization with a monomer soluble in the carrier liquid progresses, forming new particles and floating around the pigment particles.

Therefore, the effect of preventing pigment particles from agglomerating together can be obtained.

〔Effect of the invention〕

When such a liquid developer is used, interaction between pigment particles and polymer particles results in a negative polarity toner with high dispersion stability and a uniform particle size. It is possible to develop an electrostatic recording material into an electrostatic latent image, resulting in higher quality development.

Furthermore, since the image area developed with the liquid developer of the present invention has no effect on generally commercially available desensitizing liquids, it not only has a strong affinity with printing ink, that is, has a strong oil sensitivity.
Due to the effect of the fixing resin, it becomes a strong film, so when applied to offset printing plates, it has high quality and excellent printing durability.

In addition, since the liquid developer of the present invention contains pigment particles, it can be easily colored and has strong hiding power, and it can not only produce color copies but also print on deep blue photoreceptors such as phthalocyanine-based ones. Even when developing, the developed image can now be clearly inspected with the naked eye.

Furthermore, the liquid developer of the present invention does not easily form precipitates or aggregates, and even if the material is forcibly precipitated in a centrifuge, it can be redispersed with simple stirring or vibration, and is sufficiently dispersed to return to its initial dispersion state. It has excellent stability. As a result, it can be expected to have a long life as a developer, be easily stored and handled, and be expected to be effective in saving resources.

(Examples of the Invention) This invention will be described in more detail below using Examples.

(Example 1) Canon semiconductor laser beam printer LBP-1
0 was modified as follows to create a plate making machine.

First, a floppy disk drive and an interface circuit were installed on the input side to read electrical signals such as characters input from the keyboard and stored on the floppy disk, making it possible to input them to the LBP-10. In addition to replacing the photosensitive drum with an aluminum drum,
Create a groove on the drum, attach hooks that open and close at two places, wrap the semiconductor laser printing plate around the drum, fix it with hooks at the front and back, remove the transfer device, remove the rubber roll for squeezing after development, and peel it off. A claw, a conveyance device, and a control circuit for these were installed, and after development, excess developer was removed by a squeezing roll and discharged. Also, only positive charges function.

Subsequently, a printing plate for semiconductor laser was produced as described above. To 100 parts by weight of a 10 wt % solution of polyvinyl carbazole (Rubikan M170 manufactured by BASF) dissolved in a mixed solvent of tetrahydrofuran and toluene (1:1), 30 wt % of a polyester resin (Vylon 200 manufactured by Toyobo Co., Ltd.) dissolved in methyl ethyl ketone was added. Solution 1
, 7 parts by weight were added and mixed, and then coated with a wire bar to a thickness of about 3 μm on a 100 μm thick aluminum-deposited polyester film (Metal Me, manufactured by Toshi Co., Ltd.), and dried.
Next, 40 g of copper phthalocyanine and 0.5 g of tetranitrocopper phthalocyanine were dissolved in 500 g of 98% concentrated sulfuric acid with thorough stirring. The dissolved solution was mixed with water 5e to precipitate a composition of copper phthalocyanine and tetranitrocopper phthalocyanine, followed by filtration, washing with water, and drying at 120° C. under reduced pressure. To 50 g of the composition thus obtained, ε-type copper phthalocyanine (Lionol, manufactured by Toyo Ink Manufacturing Co., Ltd.)
BlueER) 100 g and methanol 5
kg to form a homogeneous mixed dispersion liquid. Thereafter, it was passed through the mouth and dried at 120° C. under reduced pressure to obtain a mixed composition.

Subsequently, a photoconductive composition was prepared based on the following procedure.

After dispersing the above composition in a magnetic ball mill for 48 hours, photoconductive zinc oxide (5AZEX2 manufactured by Sakai Kagaku Co., Ltd.)
000) was added and further dispersed in a ball mill for 6 hours. Next, the obtained mixed solution was again diluted with toluene to lower the viscosity, and applied with a wire bar to the polyvinyl carbazole layer of the aluminum vapor-deposited film coated with the polyvinyl carbazole so that the dry film thickness was 7 am, It was dried at 120° C. for 30 minutes to obtain a semiconductor laser printing plate.

<7 Gigi, Yenny G (C, I, Pigment Yellow 12) 50g, Thermolite N (Seiko Kagaku Co., Ltd.) 50
g was taken, added to Isopar G (manufactured by Esso Standard), and dispersed using a paint shaker.Isopar G was further added to the dispersion treatment solution, so that the final solid content was about 13%. diluted to

155 g of the dispersion thus obtained was taken, and further 45 g of Isopar G was added to dilute it.

Add 1 portion of n-dodecyl methacrylate (hereinafter referred to as DMA) to this.
0g added, pigment particles (Benzidine Yellow G): fixing resin (Thermolite N)! Solvent soluble monomer (DMA
)=1:1:2 ratio.

This mixed solution was put into a 500 me four-way flask equipped with a cooling tube, a thermometer, a stirring bar with stirring blades, and a nitrogen flow pipe, and nitrogen gas was introduced into the reaction system to eliminate oxygen in the system. After substitution, benzoyl peroxide (hereinafter referred to as BPO)
0. Add Ig and start stirring at the same time, 10
After minutes, polymerization was initiated by immersing the flask in a water bath maintained at 80°C.

After carrying out the above polymerization reaction for 3 hours, while maintaining the temperature at 80°C, 10 g of the monomer Tobolene M (manufactured by Shin Nakamura Chemical Co., Ltd.), which is insoluble in Ishiba-○ even after polymerization, was added to 100 me
Using a cylindrical separating funnel, the mixture was added dropwise into the flask over 10 minutes, and the polymerization reaction was continued for an additional 3 hours. This dispersion was diluted and dispersed in Isopar G so that the non-volatile components contained in 1 kg of developer were 1.0%, and 0.01% lecithin was added thereto to prepare a liquid developer for electrophotography.

Since this liquid developer has a negative polarity, it can be used as a material on the above-mentioned positively charged electrophotographic photosensitive paper. Used for developing latent images. As a result, developed images with less fog and satisfactory density were obtained. This photosensitive paper was set in a Ryobi AD-80 automatic offset printing machine, desensitized using an etching device on a tacj machine containing a Ryobi desensitizing liquid, and then printed. As a result, even after printing more than 5,000 sheets, the image is as good as when it was first printed, there is no change in print density or line width, and the reproducibility of fine line areas is also good.
Printed matter with no background fog was obtained.

After transferring the developer solution used for image production into a sealable plastic container and leaving it for about 30 days, the developer solution did not show even the slightest precipitate, and the dispersion was as good as the initial dispersion system. The condition was reproduced, and the images produced using this were good electrophotographic images that were almost as good as the initial ones.

(Comparative Example 1) A liquid developer was prepared in the same manner as in Example 1 using a system not containing Tobolene M.

Even if a large amount of the adjusting agent was added, no improvement was achieved, and only low-quality electrophotographic images were obtained.

Regarding the dispersion stability, the redispersibility was good as in Example 1, but the sedimentation rate was fast and the toner components and Isopar G were easily separated. Therefore, it is unsuitable as a liquid developer for actual use.

(Comparative Example 2) A liquid developer was prepared in the same manner as in Example 1 using a system not containing DMA.

Next, an image was produced on electrophotographic paper in the same manner as in Example 1. As a result, the pigment aggregates were slightly shiny, and a satisfactory electrophotographic image could not be obtained. In addition, although the dispersion stability was good as in Example 1, the redispersibility when used again after sedimentation was poor. Therefore, it is unsuitable as a liquid developer for actual use.

(Example 2) Hydroxyethyl acrylate (hereinafter referred to as HEA) was used instead of Topo v7M in Example 1, and a polymerization reaction was carried out for 5 hours, and this dispersion was mixed into Isopar G so that the nonvolatile components contained per 1 kg of developer were 1. A liquid developer was prepared by diluting and dispersing the mixture to a concentration of 0%.

Other conditions are the same as in Example 1.

Next, after adding a small amount of lecithin, an image was produced on electrophotographic paper in the same manner as in Example 1. A high-quality developed image with less capri was obtained. The degree of production was higher than when Tobolene M was used. Further, the redispersibility after being left for 30 days was as good as in Example 1. □Next, printing was performed in the same manner as in Example 1. As a result, even after printing more than 5,000 sheets, the image was good, there was no change in the line width, the reproducibility of fine line areas was good, and the printed matter had little background fog, as was the case at the beginning of printing.

(Example 3) After performing a polymerization reaction for 6 hours using 2-ethylhexyl acrylate instead of lJl@14+DMA, Tobolene M was added dropwise, and a polymerization reaction was performed at 90° C. for 3 hours. This dispersion was diluted and dispersed in Isopar G so that the nonvolatile component contained per 1 kg of developer was 1.0% to prepare a liquid developer.

Other conditions are the same as in Example 1.

Next, an image was produced on electrophotographic paper. As a result, high-quality images with little fog and good density were obtained. Moreover, both dispersion stability and redispersibility were very good. Furthermore, after 5,000 copies of the printed image, the fine line portions were only slightly thinner, and almost the same results as in Example 1 were obtained.

Claims (2)

[Claims] (1) The carrier liquid contains at least a copolymer of pigment particles containing a halogen atom, a cyclized rubber, a monomer soluble in the carrier liquid, and an ethylenically unsaturated compound containing a halogen group or a hydroxyl group. A liquid developer made of (2) The liquid developer according to claim 1, wherein the monomer soluble in the carrier liquid is a compound represented by the following formula. ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (In the formula, R_1 is H,
or -CH_3R_2 is an alkyl group of C_8 to C_1_6) (3) The ethylenically unsaturated compound containing a halogen group or a hydroxyl group is a compound represented by the following formula, liquid developer. ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (In the formula, R_1 is H_
1 or -CH_3R_2 is a halogen or OH-containing C_1 to C_4 alkyl group)