JPS616662A - Electrostatic photographic liquid developer - Google Patents

Abstract

PURPOSE:To enhance stability of dispersion, redispersibility, and fixability by using a copolymer resin dispersed in a nonaq. solvent contg. no dissolved resin, obtained by polymerzing specified two kinds of monomers dissolved in specified proportions in the solvent. CONSTITUTION:In a liquid developer for electrostatic photography dispsersed into the nonaq. solvent having an electric resistivity of >=10<9> OMEGA.cm and a dielectric constant of <=3.5, at least one of a unifucntional monomer A soluble in a solvent but insolubilized by polymn., and at least one of monomers B copolymerizable with the nonomer A and having a >=8C aliphatic group represented by formula I (R is >=8C aliphatic group; X is -COO- or -CONH-; Y1, Y2 are each H, alkyl, -COOR'', or -CH2COOR''; and R'' is aliphatic group) are dissolved in a solvent in a B/A ratio of 5-50wt% and copolymerized in a state of dispersion where the solvent contains no soluble resin.

Description

DETAILED DESCRIPTION OF THE INVENTION "Industrial Field of Application" The present invention is applicable to electrical resistance of 1090 cm or more and dielectric constant of 3.
The present invention relates to a liquid developer for electrostatic photography which is made by dispersing at least a resin in a non-aqueous solvent having a molecular weight of 5 or less, and particularly relates to a liquid developer having excellent storage stability, stability, redispersibility, and fixing properties.

"Prior Art" A general electrostatic photographic liquid developer is mixed with an inorganic or organic pigment or dye such as carbon black, nigrosine, or phthalocyanine blue, and a natural or synthetic resin such as acrylic resin, rosin, or synthetic rubber. is uniformly dispersed in a highly insulating, low dielectric constant liquid such as a petroleum-based aliphatic hydrocarbon, and metal soap, lecithin, and linseed are used for the purpose of making the charging characteristics of the dispersed particles uniform and strong. It contains oil, higher fatty acids, polymers containing vinylpyrrolidone, etc.

Such a developer undergoes electrophoresis in response to the charge of an electrostatic latent image formed on the surface layer of an electrophotographic photosensitive material or an electrostatic recording material in the development process, and is fixed on the surface.
The entire visible image (copied image) is formed, but in conventional liquid developers, the dispersion stabilizing resin and charge control agent diffuse into the liquid, making the charge characteristics unclear, and as a result, the image density decreases. However, there were drawbacks such as a decrease in fixing properties and an increase in background smearing, which made the copied image unclear.

In addition, these developers are difficult to use because particles tend to settle or aggregate over time (and once they settle or aggregate, they cannot be redispersed).

Furthermore, due to these drawbacks, it was unsuitable for offset printing plates, or for transfer applications such as charge transfer, suppression transfer, and magnetic transfer.

As a method for improving these problems, a method has been proposed in which a polymer is grafted onto the surface of a pigment such as carbon black to stabilize the dispersion of the particles. However, the present agent obtained in this manner had the drawbacks that the relative amount of the resin component that adhered to the image surface at the same time as the pigment was small (and the strength of the formed image after fixing was not sufficient).

Therefore, when these developers are used to form an image on a zinc oxide photoreceptor paper and used as an offset printing plate, the oil sensitivity to the printing ink and the number of printing sheets are insufficient due to the above-mentioned reasons. This caused a problem.

As another method for improving, in the above non-aqueous solvent,
A method in which monomers are polymerized to form fine resin particles in the presence of a dispersion stabilizing resin containing a graft group, and the fine resin particles are used as toner particles is disclosed in U.S. Pat. No. 3, Tata Oyro et al. However, according to the experimental results of the present inventors, although the dispersion stability of these liquid developers against natural sedimentation of particles has improved to some extent, it is not sufficient (
When the toner is placed in an actual developing device and used, the toner that adheres to various parts of the device hardens into a film, making it difficult to redisperse and furthermore causing equipment failure and smudging of copied images. There were some drawbacks, such as:

The formation of preferred resin particles by the above method has significant restrictions on the combination of dispersion stabilizer and monomer used, and generally results in particles with a wide particle size distribution containing a large amount of coarse particles. . Furthermore, there are other problems such as the fact that preferred dispersion stabilizers must be synthesized through frequent manufacturing steps.

"Problems to be Solved by the Invention" The present invention is intended to improve the above-mentioned problems of conventional liquid developers.

An object of the present invention is to provide a liquid developer with excellent dispersion stability, redispersibility, and fixing properties.

Another object of the present invention is to provide a liquid developer that enables the production of offset printing original plates having excellent printing ink oil sensitivity and printing durability by electrophotography.

Another object of the present invention is to provide a liquid developer suitable for various electrostatic photographs and electrostatic transfers in addition to the above-mentioned uses.

Still another object of the present invention is to provide a liquid developer that can be used in any system where a liquid developer can be used, such as inkjet recording, cathode ray tube recording, and recording of various change processes such as pressure changes or electrostatic changes. ``Means for solving the problems'' that may be caused by this invention The present invention has an electrical resistance value of 10109Q- or more and a dielectric constant of 3. In an electrostatographic liquid developer comprising at least a resin dispersed in a non-aqueous solvent of j or less, the resin contains a monofunctional monomer that is soluble in the solvent but becomes insolubilized by polymerization. Body (A) and general formula (I)
At least one monomer (B)' each containing an aliphatic group having a carbon number r or more represented by and copolymerizing with the monomer (A) in a polymerization reaction, and the monomer (B) e monomer (A
) against! A liquid developer for electrophotography, characterized in that it is a copolymer resin obtained by dispersing and polymerizing a solution containing ~j0% by weight in the absence of a resin soluble in the solvent.

General formula (I) In formula (I), R is an aliphatic group having at least r carbon atoms, and X is -
COO-1-CON) i- or R' ■ -CON- (R' indicates aliphatic fund), ¥1 and Y
2 u, which may be the same or different, hydrogen atom, alkyl group, -COOR" or -CH2COOI'("(R"
represents an aliphatic group).

Used in the present invention, the electrical resistance is 1O9Ω·α or more, and the dielectric constant is 3. ! As the following non-aqueous solvent, preferably linear or branched aliphatic hydrocarbons, alicyclic hydrocarbons, aromatic hydrocarbons, barogenated hydrocarbons, etc. can be used. More preferred in terms of volatility, stability, toxicity, odor, etc., are petroleum solvents such as octane, isooctane, decane, indecane, nonane, dodecane, isododecane, decalin, and isoparaffin. (Isopar: Exxon's product name), Shell Silua 1 (Shell Oil's product name), Amsco OMS, Amsco 1 Ato solvent (
Spirits Co., Ltd.'s product name) etc. are used alone or in combination.

The non-aqueous dispersion resin, which is the most important component in the present invention, contains the monomers (A) and (B) in a non-aqueous solvent.
! A product manufactured by dispersion polymerization is used.

Basically, any non-aqueous solvent can be used as long as it is miscible with the carrier liquid of the electrostatic photographic liquid developer, but the same solvent as the carrier liquid may be used at the stage of producing the resin dispersion. is usually preferable.

That is, as the solvent used in producing the dispersion resin, linear or branched aliphatic hydrocarbons, alicyclic hydrocarbons, aromatic hydrocarbons, halogenated hydrocarbons, etc. are preferable.

More specifically, hexane, octane, isooctane,
Decane, indecane, nonane, dodecane, indodecane, Isopar E, a petroleum solvent based on innomilafin,
Isopar G1 Isopar H.

Isoperm 1 Ciercilua/, Amsco OM8, etc. are preferred.

The monomers used in producing the non-aqueous dispersion resin include a monofunctional monomer (A) that is soluble in the solvent but becomes insolubilized by polymerization, and a carbon compound represented by the general formula (I). The monomers (B) can be classified into monomers (B) which contain aliphatic groups of more than 100% and copolymerize with the monomer (A).

Examples of the monomer (A) include vinyl esters or allyl esters of aliphatic carboxylic acids having 7 to 3 carbon atoms (propionic acetate, butyric acid, monochloroacetic acid, etc.), crotonic acid, itaconic acid, maleic acid, etc. Alkyl esters or alkylamides of unsaturated carboxylic acids having a carbon number of up to 3, styrene derivatives such as α-methylstyrene, unsaturated carboxylic acids such as crotonic acid, maleic acid, itaconic acid or their anhydrides, hydroxyethyl methacrylate,
Hydroxyethyl acrylate, diethylaminoethyl methacrylate, N-vinylpyrrolidone, and the like can be mentioned.

To further explain the monomer represented by the general formula (I) used in the present invention, in the general formula (I), preferably, R is an optionally substituted alkyl group having a total carbon number/2 or more, or a total carbon number 12 or more alkenyl groups, XH-
COO-1-CONH-1R' or -CON- (wherein R' represents an aliphatic group having 1 to 3 λ carbon atoms (the aliphatic group is, for example, an alkyl group, an alkenyl group, or an aralkyl group)) Representation, Yl
and Y2 may be the same or different and represent a hydrogen atom, a methyl group, -COOR" or -CH2COOR" (However, R# is an alkyl group, alkenyl group, or alkenyl group having 1 to 3 carbon atoms.
Indicates an aralkyl group or a cycloalkyl group].

Specific examples of the monomer (B) represented by the above general formula (I) include aliphatic groups having a total of 10 to 32 carbon atoms (including substituents such as halogen atoms, hydroxy groups, amino groups, and alkoxy groups). acrylic acid, methacrylic acid, crotonic acid, maleic acid, Esters of unsaturated carboxylic acids such as itaconic acid (aliphatic groups such as decyl, dodecyl, tridecyl, tetradecyl, hexadecyl, octadecyl, docosanyl, dodecenyl, hexadecenyl, oleyl, rillyl, tocosenyl group, etc.), the above-mentioned amides of unsaturated carboxylic acids (the aliphatic group represents the same thing as shown in the esters), and the like.

The dispersion resin of the present invention is composed of at least 7 or more types of monomer A and monomer B, and the important thing is that if the resin synthesized from these monomers is insoluble in the non-aqueous solvent, the desired It is possible to obtain a dispersion resin of.

More specifically, it is preferable to use r-sow amount of monomer B represented by general formula (I), more preferably 0 to 30% by weight of monomer A to be insolubilized. . Further, the molecular weight of the dispersion resin of the present invention is IO3 to 106, preferably 10' to 106.

Examples of these dispersion resins are shown below, but the scope of the present invention is not limited thereto.

(I) CH3 (2) CHa(31CH3 (4) CH3CH3 CH3 0匈CH3 COOC10H21 ■ CH3 ■ H3 ” 05) CH3CH3 In order to produce the dispersion resin used in the present invention, the above-mentioned steps are generally carried out. monomer (A) and monomer (B)
may be polymerized by heating in a nonaqueous solvent in the presence of a polymerization initiator such as benzoyl peroxide, azobisisobutyronitrile, butyllithium, titanium tetrachloride, or the like. in particular,
A method of adding a polymerization initiator to a mixed solution of monomers (A) and monomers (B). Alternatively, a method of optionally adding the remaining monomer mixture together with a polymerization initiator into a mixed solution containing a part of the mixture of monomer (A) and monomer (B); There are methods in which a mixed solution of monomers is optionally added together with a polymerization initiator in an aqueous solvent, and production can be achieved using any of these methods.

The total number of monomers (A) and monomers (B) is 10
The amount is about 1 to 10 parts by weight, preferably 10 to 0 parts by weight.

The amount of polymerization initiator is 0.7 to 7% (weight) of the total monomer amount
is appropriate.

Further, the polymerization temperature is about 6so~/I00C, preferably about 1JO~/20°C, and the reaction time is preferably /~1 hours.

As described above, the non-aqueous dispersion resin produced according to the present invention exists as fine particles with a uniform particle size distribution, and at the same time exhibits extremely stable dispersibility, and can be used repeatedly over a long period of time, especially in existing equipment. It has good dispersibility (and is easy to re-disperse, and no stains are observed on any part of the device).Furthermore, when it is completely fixed by heating, etc., a strong film is formed, which is good. It showed good fixing properties.

Conventionally, in the so-called polymerization granulation method, which produces a dispersed resin through a polymerization reaction using a monofunctional monomer that is soluble in non-aqueous solvents but becomes insolubilized by polymerization, it has been used to stabilize the dispersed resin. A resin soluble in the solvent is always used in combination. Manufactured by dispersing and polymerizing monomers (A) and monomers (B) in the dispersion resin used as toner particles of the liquid developer of the present invention without using the above-mentioned soluble resin for dispersion stabilization. It is characterized by being In order to form all the preferable resin particles in the present invention, the monomer (
The copolymerization reactivity of B) is equal to or higher than that of monomer (A), and the total number of carbon atoms in the alkyl or alkenyl groups contained in monomer (B) is t or more. is important.

That is, to explain with a specific example, when a polymerization reaction is carried out using vinyl acetate as the monomer (A) and stearyl methacrylate, vinyl stearate, and octadecyl vinyl ether as the monomer (B), the monomer ( Preferable resin particles were formed only when stearyl methacrylate was used as B), and coagulates were formed when vinyl stearate and octadecyl vinyl ether were used. This means that the copolymerization reactivity of vinyl acetate and each of the above three monomers is
As known from the Polymer Handbook, it is believed that the main thing is that only stearyl methacrylate is larger than vinyl acetate.

Furthermore, when polymerizing using hexyl methacrylate, octyl methacrylate, and dodecyl methacrylate as the monomer (B), [91, the ester chain length of methacrylic acid is short (as the average particle diameter of the resin particles becomes gradually increased, and in the case of the hexyl group, the number of carbon atoms in the ester chain length was r or more and became coarse particles.

From the above experimental facts, the remarkable performance improvement effect of the present invention is due to the copolymerization of a part of the monomer (B) used at the particle interface of the insolubilized and dispersed resin. It is assumed that this is due to the fact that the particle surface has been modified in some way.

In the present invention, a coloring agent may be used if necessary, and the coloring agent is not particularly specified; various conventionally known pigments or dyes can be used.

When coloring the dispersion resin itself, for example, one method of coloring is to physically disperse the dispersion resin using pigments or dyes, and there are a large number of known pigments or dyes. There is. Examples include magnetic iron oxide powder, powdered lead iodide, carbon black, nigrosine, alkaline flu, Noin the Yellow, quinacridone red, and phthalocyanine blue.

Another coloring method is JP-A-Shoj7-4AI7.
There is a method of dyeing a dispersed resin material with a preferred dye as described in Japanese Patent Application Laid-Open No. 3-3-1≠022.
There is a method of chemically bonding the dispersed resin material and the dye. There is a method of making a dye-containing copolymer using the monomer contained in the dye.

Various additives may be added to the liquid developer of the present invention in order to strengthen the charging characteristics or improve the image quality, for example, Yuji Harasaki, "Electronic Photography", Vol.
No., Hirohiro page.

Examples jt Hacynoethylhexylsulfoconolinic acid metal salts, naphthenic acid metal salts, higher fatty acid metal salts, lecithin,
Additives such as a copolymer containing a poly(vinylpyrrolidone) hemi-maleic acid amide component or a copolymer containing a hemi-maleic acid amide and maleimide component can be mentioned.

The amounts of each main component of the liquid developer of the present invention are explained below.

The amount of toner particles mainly composed of resin and colorant gold is 0.2 parts by weight per 1000 parts by weight of carrier liquid! O parts by weight are preferred. If it is less than 0.1 parts by weight, the image density will be insufficient, and if it is more than 10 parts by weight, fogging will tend to occur in non-image areas. A carrier liquid soluble resin such as the above-mentioned dispersion stabilizer is also used as necessary, and can be added in an amount of about 0.1 part by weight to 100 parts by weight per 1,000 parts by weight of the carrier liquid.

The charge control agent as described above is preferably 0.00/-/0 parts by weight per 1000 parts by weight of the carrier liquid, and various additives may be added as necessary, and the total amount of these additives is , the upper limit is regulated by the electrical resistance of the developer.

In other words, if the electrical resistance of the liquid developer with toner particles removed is less than 109Q-an, it will be difficult to obtain high-quality continuous gradation. It is necessary to.

Embodiments of the present invention are illustrated below, but the content of the present invention is not limited thereto.

Production example 1 of resin particles: Compound vinyl acetate ioog1 lauryl methacrylate 209 and indodecane of specific example (I), ? The r og mixed bath liquid was heated to a temperature of 700C while stirring under a nitrogen stream.

u, , 2'-Azobis(isobutyronitrile) (abbreviations A, 1.B, N)/, 7II were added and reacted for a period of time. 30 minutes after the addition of the initiator, the solution began to become cloudy and the reaction temperature rose to Hrz0c. After cooling, the white dispersion obtained by passing through a 200 mesh nylon cloth was a latex with a polymerization rate of 11% and an average particle size of O0λjμ.

Production Example 2 of Resin Particles: A mixed solution of 100 fl of the compound vinyl acetate of Example (4), 1 g of stearyl methacrylate, and 3119 indodecane was heated to a temperature of 7Q0C while stirring under a nitrogen stream. A, 1.13. Nz, 7
y was added and reacted for 4 hours. After adding initiator and μθ minutes, -
The solution began to become cloudy and the reaction temperature rose to t4rz0c.

After cooling, the resulting white dispersion was passed through a nylon cloth made of CoOO mesh.The obtained latex had a constant polymerization rate of rr% and an average particle size of 0.20 μm.

Production example 3 of resin particles: Compound vinyl acetate i of specific example 01
oog, stearyl acrylate 109 and Isopar□5top at a temperature of 7 while stirring under a nitrogen stream.
! It was heated to 0CVc.

A.1. 7 g of B and N/ were added and reacted for 6 hours.

20 minutes after the addition of the initiator, white turbidity occurred, and the reaction temperature was reduced to rro.
It rose to c. After cooling, it was passed through a nylon cloth with a λOO mesh, and the obtained white dispersion was a latex with a polymerization rate of 20% and an average particle size of O0λ.

Production Example 4 of Resin Particles: A solution of 310 g of the compound Shell Silua of Specific Example (4) was heated to a temperature of 7j'C while stirring under a nitrogen stream.

Vinyl acetate 1009. Stearyl methacrylate 1.2
g and A, 1. B, N/, 7. A mixed solution of S+ was added dropwise over a period of 2 hours, and the mixture was further stirred for an additional Vcg period. After cooling 2
The resulting white dispersion was a latex with a polymerization rate of rs% and an average particle size of 0.degree. 20 .mu.m.

Production Example 5 of Resin Particles: A mixed solution of the compounds vinyl acetate ioog, crotonic acid'g, stearyl methacrylate 10g, and iso, eB<<+rg of specific example (5) was heated to a temperature of 700C while stirring under a nitrogen stream. . A, 1
．． B, N/, 7. Add S+ and react for an hour at a temperature of 100
The temperature was raised to 0C and the mixture was stirred for 1 hour, and the remaining vinyl acetate was distilled off. After cooling, the resulting white dispersion was passed through a 200-mesh nylon cloth, and the resulting white dispersion was a latex with a polymerization rate of rr% and an average particle size of 0.11 μm.

Production example t of resin particles: A mixed solution of the compound vinyl acetate Ijtg of specific example (5), N-vinylpyrrolidone/jg, stearyl methacrylate lOg and n-decane 310g was heated to a temperature of 7j0C while stirring under a nitrogen stream. .

A.1. B.N.

/, 7g was added and reacted for a long time, and then A, 1. B.N.

o, sg@ were added and reacted for 2 hours. After cooling, the resulting white dispersion was passed through a 200-mesh nylon cloth with a polymerization rate of t.
The latex was 7% and had an average particle size of 0.23.

Example 1 Poly(lauryl methacrylate) iog, nigrosine 1
The mixture was placed in an India shaker (Tokyo 111 machine ■) together with 0fi and Shell Silua/3011ffj russian beads, and dispersed for 0 minutes to obtain a fine dispersion of nigrosine.

Resin dispersion 309 of resin particle production example 2), nigrosine dispersion λ,! A liquid developer for electrostatography was prepared by diluting it to 9'f Nigelcil 7/1.

These liquid developers are processed using a fully automatic electronic plate making machine ELP210 (
ELP Master (manufactured by Fuji Photo Film ■), which is an electrophotographic light-sensitive material, was exposed and developed using it as a developer for Fuji Photo Film ■.

Further, after processing 2,000 ELP masters, the developing device was inspected for any toner adhesion stains, but no stains were found on the device.

Offset printing master plates (ELP masters) obtained using the developer of the present invention had very clear images both in the first development and after 2000 sheets were developed. Furthermore, when 3,000 sheets were printed using these master platers in a conventional manner, clear printed matter could be obtained even after printing 3,000 sheets.

Example 2 A mixture of the white background dispersion 100I obtained in Production Example 2 of resin particles and Sumikalon Black/, jp was heated to a temperature of 1000C.
The mixture was heated and stirred for a while.

After cooling to room temperature, the remaining dye was removed by passing it through a 200 mesh nylon cloth until the average particle size was 0. A black resin dispersion with a thickness of 0 μm was obtained.

A liquid developer was prepared by diluting 3ill of the above black resin dispersion and the octadecene-maleic acid monohexadecylamide copolymer to 0.02jflf Shell Sila/,/It.

When this was developed using the same device as in Example 1, the result was 200
Even after developing 0 sheets, no toner adhesion stains occurred on the device.

Example 3 Production of resin particles A mixture of the white dispersion lOog obtained in Example 5 and Victoria Blue 8311 was heated to a temperature of 700-r
The mixture was heated to 0cvc and stirred for 4 hours. 20. After cooling to room temperature.
The remaining dye was removed by passing it through a 0 mesh nylon cloth to obtain a blue resin dispersion with an average particle size of o and it μm.

The above blue resin dispersion 329, zirconium naphthenate o
, ozg@Isopar H/l to prepare a liquid developer.

When this was developed using the same device as in Example 1, 20
Even after developing 3,000 sheets, there was no toner adhesion to the device.Also, the image quality of the obtained offset printing master plate was clear, and the image quality of the printed matter after printing 3,000 sheets was also very clear.Example of production of resin particles 32 g of the white resin dispersion obtained in Example 2, the nigrosine dispersion obtained in Example 1,!
I and half docosanyl amide of copolymer of diimbutylene and maleic anhydride 0.02 flf isoper Gll
A total liquid developer was prepared by diluting it to .

This was developed using the same device as in Example 1, and the result was 1.20
Even after developing 00 sheets, there is no toner adhesion/stain lever on the device (
I couldn't see it. Furthermore, the image quality of the obtained master plate for offset printing and the image quality of the printed matter after printing 3000 sheets were both clear.

Furthermore, after leaving this developer for 3 months, the same treatment as above was carried out, but there was no difference in the results from before.

Example 10g of this poly(decyl methacrylate), iso/R-H
The mixture was placed in a paint shaker together with Ofl, Alkali Blue tg+, and glass beads, and dispersed for 2 hours to obtain a fine dispersion of Alkali Blue.

3oy of white resin dispersion obtained in Production Example 3 of resin particles,
A liquid developer was prepared by diluting 2 g of the above alkali blue dispersion and 0.029 g/l of a semi-docosanylamidated copolymer of diisobutylene and maleic anhydride.

When this was developed using the same device as in Example 1, the result was 200
Even after developing 0 sheets, no toner adhesion stains were observed on the device. Furthermore, both the image quality of the obtained master plate for offset printing and the image quality of the printed matter after printing 500 sheets were very clear.

Claims (1)

[Claims] The electrical resistance value is 10^9 Ω·cm or more, and the dielectric constant is 3.
A liquid developer for electrostatography comprising at least a resin dispersed in a non-aqueous solvent of 5 or less, in which the resin is a monofunctional monomer that is soluble in the solvent but becomes insolubilized by polymerization. (A) and at least one monomer (B) each containing an aliphatic group having 8 or more carbon atoms represented by general formula (I) and copolymerizing with monomer (A) in a polymerization reaction. A copolymer obtained by dispersion polymerizing a solution containing the above and monomer (B) in an amount of 5 to 50% by weight based on monomer (A) in the absence of a resin soluble in the solvent. A liquid developer for electrostatic photography characterized by being a polymeric resin. General formula (I) ▲Mathematical formulas, chemical formulas, tables, etc. are available▼ In formula (I), R is an aliphatic group with 8 or more carbon atoms, and X is
-COO-, -CONH- or ▲Mathematical formulas, chemical formulas, tables, etc.▼(R' represents an aliphatic group) as Y_1 and Y_
2 may be the same or different and represent a hydrogen atom, an alkyl group,
-COOR'' or -CH_2COOR''(R'' represents an aliphatic group).