JPS60262175A - Liquid developer for electrostatic photography - Google Patents

Abstract

PURPOSE:To improve the shelf stability and to form a high quality image by dispersing a toner contg. a coloring agent and a binding resin consisting of specified monomers as the principal components in a liq. carrier contg. aliphatic hydrocarbon as the principal component. CONSTITUTION:A monomer A represented by formula I (where R is H or CH3, X is COOCnH2n+1 or OCOCnH2n+1, and n is an integer of 6-20) is polymerized with a monomer B represented by formula II (where R' is H or CH3, and m is an integer of 1-20) in the presence of a polymn. initiator in an aliphatic hydrocarbon solvent to obtain a binding resin. A toner contg. a coloring agent and said binding resin as the principal components is dispersed in a liq. carrier contg. aliphatic hydrocarbon as the principal component to prepare a liq. developer for electrostatic photography. The preferred weight ratio of the monomer A / the monomer B is (50-99.5)/(0.5-50), the preferred amount of the polymn. initiator is 0.1-5wt% of the amount of the monomers.

Description

DETAILED DESCRIPTION OF THE INVENTION TECHNICAL FIELD This invention relates to electrostatographic liquid developers and, more particularly, to improvements in binders used in toners.

Conventional technology The main components of general liquid developers for electrostatic photography are colorants such as carzen black, organic pigments or dyes, and binders made of synthetic or natural resins such as acrylic resins, phenol-modified alkyd resins, rosins, and synthetic rubbers. And this, lecithin,
A toner containing a polarity control agent such as metal soap, linseed oil, or higher fatty acid is dispersed in a carrier liquid containing a highly insulating, low dielectric constant solvent such as petroleum-based aliphatic hydrocarbon. be.

During the development process, such toner undergoes electrophoresis in accordance with the charge of the electrostatic latent 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, causing aggregation and making the polarity unclear, resulting in significant deterioration of image quality, especially image density. In addition, there are
The adhesive strength of the toner, and therefore the fixing power of the image, was weak, and the durability when making continuous copies (the number of copies until the image density decreased to a predetermined level) was insufficient. The lack of durability is thought to be due to the fact that the pigment and resin constituting the toner are not sufficiently adsorbed in the carrier liquid, which causes the compositional balance of the developer to change as the number of copies increases.

Conventionally, the manufacturing method of non-aqueous copolymer resin used as a binder for toner involves using a polymerization initiator such as pencil peroxide in a non-aqueous solvent such as a petroleum-based aliphatic hydrocarbon. Polar reactive monomers such as glycidyl (meth)acrylate, (meth)acrylic acid, (meth)acrylate having a furfuryl group, 2-hydroxyethyl/I/(meth)acrylate, lauryl (meth)acrylate, stearyl (meth)acrylate, etc. ) A method of polymerizing reactive monomers such as acrylate, 2-ethylhexyl (meth)acrylate, and vinyl laurate is known. However, since the former type of reactive monomer exhibiting polarity has low reactivity, the resulting polymer also has weak polarity (for this reason, it is difficult to obtain a good electrostatographic liquid developer even if such a polymer is used). Can not.

OBJECTIVES The first objective of the present invention is to provide an electrostatographic liquid developer that can form high-quality images by clarifying the polarity of the toner and improving its storage stability.

A second object of the present invention is to provide a liquid developer for electrostatography that has improved image fixing properties by improving the adhesion of toner.

A third object of the present invention is to provide a liquid developer for electrostatic photography that can greatly increase the number of durable sheets by increasing the adsorption power between the pigment and the resin.

Structure The present invention relates to an electrostatographic liquid developer comprising a toner containing a colorant and a binder as main components dispersed in a carrier liquid containing an aliphatic hydrocarbon as the main component, wherein the binder is an aliphatic hydrocarbon. In the presence of a polymerization initiator in an ice solvent, the general formula (I
)CK, =C... (11 (However, R is -H or -CH3, X is -COOCHz
n+x or -0COCnHtn+t, n is an integer from 6 to 20. ) and the general formula (I
t) Using a resin obtained by polymerizing a system containing at least Shitsummer B represented by 1 (where R' is -H or -CH, m is an integer from 1 to 20) It is characterized by

Incidentally, the inventors of the present invention have conducted various studies regarding the properties of the binder (resin) that should be used in order to achieve the above object, and as a result, have reached the following conclusion. That is, the properties of this I remer are: 1) The solvate component is present in the polymer, and the polymer has a uniform crosslinked structure.

2) Contains a crosslinking monomer component that does not cause a rapid crosslinking reaction.

3) Contains 5 monomer components that cause the co-plating reaction and the crosslinking reaction to occur separately.

4) it has an affinity for pigments, and 5) it does not dissolve in non-aqueous solvents and therefore can simply be dispersed in non-aqueous solvents.

Subsequently, the present inventors conducted research on various polymers from these viewpoints, and found that the unsaturated compound represented by the general formula (I) (monomer A) is a monomer that is solvent-compatible before and after polymerization. ) and monomer B represented by the general formula (■) as a monomer that can serve as a crosslinking component after polymerization are copolymerized and crosslinked to produce a copolymer that is optimal. The present invention was completed based on such knowledge.

In order to produce the binder (polymer) of the present invention, 7mer-A and mono-q-f3 are mixed in an aliphatic hydrocarbon solvent in the presence of a polymeric initiator such as benzoyl peroxide or azopisisozotyronitrile. The heating polymerization may be carried out in one step or two steps.

Here, "one step" means that monomer A and monomer B are heated once to a relatively high temperature of about 60 to 150°C in the presence of a polymerization initiator such as benzoyl peroxide that causes polymerization at a relatively high temperature. This means that a polymerization reaction is carried out. Also □ “Two-stage”, Yu% / q −A I
%/~-8□ months, after first heating to a relatively low temperature of about 60 to 90°C to cause a polymerization reaction in the presence of a polymerization initiator such as azopisisozothyronitrile that causes polymerization at a relatively low temperature. 1 Add the above-mentioned high-temperature polymerization initiator to the reaction solution and heat it to a relatively high temperature of about 80 to 150°C in the presence of this high-temperature polymerization initiator to perform the 1 reaction again, or monomer B alone. is first subjected to a polymerization reaction under similar low-temperature conditions, then monomer A and a high-temperature polymerization initiator are added to the reaction solution, and the polymerization reaction is conducted under similar high-temperature conditions in the presence of this high-temperature polymerization initiator. means.

Monomer A/monomer B ratio is 50~99.510.5~
Approximately 50% (by weight) of the polymerization initiator is suitable, and the amount of the polymerization initiator is approximately 1 to 5% (by weight) of the amount of monomers (in the case of one stage, all seven monomers) used in each polymerization step. It is.

In the present invention, other polymerizable monomers, silica fine particles, wax or polyolefin having a softening point of about 60 to 130°C can be added in the resin manufacturing process.

When fine silica particles are used, it is thought that the copolymer is obtained with fine silica particles incorporated into its crosslinked structure. In this case, it is thought that the silica itself will not undergo sudden physical changes such as dissolution during the reaction. In any case, in the case of silica, the dispersion stability can be further improved by making the specific gravity similar to that of aliphatic hydrocarbon, which is a dispersion medium, and by preventing gelation of the copolymer.

If wax or polyolefin is used (in the case of using wax or polyolefin), these will be dissolved in the reaction thread by heating during the polymerization reaction, but after the reaction, they will be precipitated into particles by cooling, and the copolymer will be adsorbed on these fine particles. Here, wax or polyethylene has a specific gravity similar to that of the dispersion medium, prevents gelation of the copolymer, and has a molecular structure similar to that of the dispersion medium, so wax or polyethylene is useful for improving dispersion stability. Not only is it useful, but it also has a low softening point (・, so it also helps improve adhesion.

The amount of silica, wax or polyolefin added is suitably about 5 to 50 parts by weight per 100 parts by weight of the copolymer.

Next, Q to explain the materials used in the present invention. Specific examples of monomer A represented by general formula (1) include lauryl methacrylate, lauryl acrylate, stearyl methacrylate, stearyl acrylate, 2
~Ethylhexyl acrylate, 2-ethylhexyl acrylate, dobuflu methacrylate, dodecyl acrylate, cyclohexyl acrylate, cyclohexyl methacrylate, hexyl methacrylate, hexyl acrylate, octyl methacrylate, octyl acrylate, cetyl methacrylate, cetyl acrylate,
vinyl rough plate.

Examples include vinyl stearate.

Specific examples of the monomer B represented by the general formula (It) include the following.

(Margin below) 1 0 I CH-C,.

cH,/N(0Hz)so CH=C″l, (8) 1 1 1 Polymerization initiators include, in addition to those mentioned above, penzoyl dimethylanili peroxide, diethylzinc, and hydrogen peroxide for low-temperature polymerization. etc. Also, for high temperature polymerization, lauryl, e-
Examples include oxide, t-butyl peroxide, di-t-butyl peroxide, cumene hydroperoxide, and dicumyl peroxide.

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

Example of polyethylene Union Carbide DYNI 102DYNF
102 DYNH102 DYNJ 102 DYNK I O2 -F Near '9''7 (US) 0RLIZON s05
1160RIJZON 705 116 0RLIZON 50 126 Philips (US) MARLEX 1005 92 Dupont (US) ALATHON -3103ALATH
ON 10 96 ALATHON 12 B 4 ALATHON 14 80 ALATHON 16 g 5 ALAT)ION 20 86 ALATHON 22 84 ALATHON 2s 96 Allied Chemical (USA) AC-Polyethylene 170
2 98 Manufacturer Product name Softening point ('C) Allied Chemical (US) AC-4 Lietelene 6 & 6
A 102AC-Polyethylene 615 105 Sanyo Chemical Sunwax 131-P 108 Sunwax 151-P 107 Sunwax 161-1 111 Sunwax 165-P 107 Sunwax 171-P 105 Su/Wax E-20095 Wax (paraffin wax) Example Manufacturer Product Name Softening Point (°C) Genuine Chemical Paraffin Wax 60-98 Kobayashi Kako Sarashi Beeswax 565 Setanol 80 Mizuben Kako Sarashi Beeswax 65 Steel Manufacturing Frozen 110 Examples of the above-mentioned "other polymerizable monomers" include: Su,,1.・
fV7-2-'1"'.= ) 02jLz7.1 Vinyl acid, vinylpyrrolidone, dimethylaminoethyl methacrylate, dimethylaminoethyl acrylate, diethylaminoethyl methacrylate, diethylaminoethyl acrylate, and the like.

Next, specific examples of water-insoluble tS<aliphatic hydrocarbons include kerosene, ligroin, cyclohexane, n-hexane, n-pentane, n-hezotane, n-octane, isooctane, indodecane, isononane (the above commercially available The products are Exxon's Iso/(-H, G, L,
Examples include Naphtha-Ya 6 and Shell Sol manufactured by Shell Oil Co.).

These aliphatic hydrocarbons have high insulating properties (electrical resistance of 10Ω
It is a solvent with a low dielectric constant (dielectric constant of 3 or less). Moreover, aromatic solvents such as benzene and toluene can also be added to these aliphatic solvents as long as they are in small amounts.

Here, an example of manufacturing the binder (a non-aqueous dispersion of the resin) is as follows.

Production Example 1 3Δ equipped with a stirrer, temperature gauge, cooling pipe and dropping funnel
Kerosene 5001 in the flask! Lauryl acrylate) was added to the mixture, heated to 85°C, and stirred.
10011. The monomer 501 of (1) above! and azobisisobutyronitrile 5I were added dropwise over 2 hours using a dropping funnel. °Then, after a polymerization reaction was carried out at this temperature for 4 hours with stirring, 3 g of di-t-zotyl, e-oxide was added.
was added and further polymerized for 6 hours at 110°C, resulting in a polymerization rate of 965, a particle size of 2 to 4μ, and a viscosity of 180 cp.
A resin dispersion was obtained.

Production Example 2 400I of n-hexane was placed in the flask used in Production Example 1, heated to 60°C, and lauryl methacrylate (95F!) was added while stirring. , Monomer 25J9 of the above (3) and azobisisobutyronitrile 29 were added dropwise through a dropping funnel over 1 hour.

Thereafter, a polymerization reaction was carried out at this temperature for 6 hours. Next, 4 g of benzoyl peroxide was added and the polymerization reaction was carried out at 90°C for an additional 4 hours with stirring, resulting in a polymerization rate of 94.4%.
A resin dispersion having a particle size of 5 to 6 μm and a viscosity of 160 cp was obtained.

Production Example 3 400g of Isopar G was placed in the flask used in Production Example 1, heated to 90°C, and while stirring, hexyl methacrylate zooy, 5g of methacrylic acid, 10.9g of the monomer of (6) above, and 3g of benzoyl peroxide were added. The mixture was added dropwise using a dropping funnel over 4 hours. Next, styrene 3
0 Jil and 3 g of benzoyl peroxide were added and Nitogane reaction was carried out at the above temperature for 4 hours with stirring, and the polymerization rate was 9.
A non-aqueous resin dispersion with a particle size of 8.6%, a particle size of 5 to 9 microns, and a viscosity of 290 cp was obtained.

Production Example 4 200 g of n-hexane and 50 g of polyethylene (AC polyethylene 1106, manufactured by Allied Chemical Co., Ltd.) were placed in the flask used in Production Example 1, and heated to 90°C to dissolve the polyethylene.

Monomer 2009 of the above (9) and 1:1 of azobisisobutyronitrile were added dropwise to this mixture over a period of 2 hours using a dropping funnel, and a polymerization reaction was carried out at the above temperature for 6 hours while stirring. Next, cetyl methacrylate 100.9 and t-
By adding 5 g of butyl peroxide and carrying out a polymerization reaction at 130°C for 6 hours with stirring, the polymerization rate was 96.0.
A polyethylene-containing resin dispersion with a viscosity of 330 cp was obtained.

Production Example 5 AC polyethylene 61 was added to the resin dispersion obtained in Production Example 2.
5 to 181! In addition, after heating and dissolving at 90° C. for 2 hours, the mixture was allowed to cool to produce a polyethylene-containing resin dispersion having a viscosity of 620 cp.

Production Example 6 401! of Sunwax 13i-p was added to the polyethylene-containing resin dispersion obtained in Production Example 4. In addition, the mixture was heated and dissolved at 90° C. for 2 hours, and then allowed to cool to produce a wax and polyethylene-containing resin dispersion having a viscosity of 360 cp.

Dispersion development using the thus obtained copolymer::11
To make a coloring agent, generally 1 part by weight of colorant is mixed with 0 copolymer.
．． 3 to 3 parts by weight, and add 10 to 20 parts by weight of a petroleum-based aliphatic hydrocarbon or halogenated aliphatic hydrocarbon carrier liquid.
The toner may be sufficiently dispersed in the presence of parts by weight using a dispersing machine such as an attritor, mail mill, or kedimir to obtain a concentrated toner, which is then diluted 5 to 10 times with a similar solvent.

In this case, the copolymer dispersion (resin dispersion) obtained as described above can be used as it is as the copolymer and solvent. It is also possible to add other resins other than the copolymer and polarity control agents such as metal soaps.

Coloring agents include dyes or pigments such as carbon silk, oil sol, alkali blue, phthalocyanine blue, 7-thalocyanine green, spirit black, aniline black, oil violet, benzidine yellow, methyl orange, brilliant carmine, fast red, and crystal violet. is excited.

Other resins that can be added to the developer include acrylic resins, ester gums, natural resins such as hardened rosin, and maleic acid resins modified with these natural resins, phenolic resins, polyesters, pentaerythritol resins, and the like.

In addition to metal soaps, examples of polarity control agents include lecithin, linseed oil, and higher fatty acids.

Next, examples will be shown.

Example 1 Carbon black (MA-11 manufactured by Mitsubishi Car Inc.) l
OP "The resin dispersion 5011 Kerosene 100.9 obtained in Production Example 1 was dispersed for 6 hours in a kedimir to obtain a concentrated toner with a viscosity of 16.8 cp, and the 10II was dispersed in kerosene 11 for electrostatic photographic liquid development. I made a drug.

Subsequently, this developer was placed in a commercially available electrophotographic copying machine and copies were made on commercially available zinc oxide photosensitive paper, resulting in copies with an image density of 1.29 and an image fixation rate of 83.3%. In addition, the fixing rate (@ is yXloo (X is the initial image density of the copy, Y is the image density after erasing 5 times with an eraser tester)
It was calculated from the formula.

Also, when we tested the durability of the developer by continuously copying until the image density decreased by 0.60K, we found that it was zooooo
It was in good condition.

Furthermore, after storing the developing solution at 50°C for 3 months to forcefully deteriorate it, we made copies in the same manner as above and measured the image density, which was 1.26, which confirmed that there was almost no deterioration. Ta.

Examples 2 to 11 A liquid developer was prepared in the same manner as in Example 1 using the pigment, resin and dispersion medium shown in Table 1 and according to the dispersion method described in the same table, and then in the same manner as in Example 1. After conducting the test, Table-2
I got the result.

(Hereinafter referred to as margins) Effects As described above, by using the liquid developer according to the present invention, a large number of high-quality copies can be obtained. Furthermore, since this developer has extremely good toner dispersibility, it also has excellent storage stability.

Claims (1)

[Scope of Claims] 1. A liquid developer for electrostatography comprising a toner mainly composed of a colorant and a binder resin dispersed in a carrier liquid mainly composed of an aliphatic hydrocarbon, wherein the resin is an aliphatic hydrocarbon. General formula (1) in the presence of a polymerization initiator in a group hydrocarbon solvent (wherein, R is -H or -CH, X is -COOCnHz)
n++ or -0COCnHtn++, n is 6 to 2o
is an integer. ) and the general formula (
It) (However, R' is -H or -CH8, m is 1 to 20
is an integer. 1. A liquid developer for electrostatic photography, characterized in that the main component thereof is a resin obtained by polymerizing a system containing at least monomer B represented by: