JPS6218575A - Liquid developer for electrostatic photography - Google Patents

Abstract

PURPOSE:To improve the fixing performance of a wet type toner by dispersing a specific toner fixable by UV rays into an aliphat. hydrocarbon solvent. CONSTITUTION:The toner fixable by UV rays contg. a coloring agent, the monomer expressed by the formula 1 or the polymer thereof (component A) and the monomer expressed by the formula 2 or the compsn. contg. said monomer or the polymer thereof or the copolymer thereof (component B) as the essential components is dispersed into the aliphat. hydrocarbon solvent. The ratio of the component B with the component A is adequately about 0.01-1:1 (weight). The practicable example of the component A includes a lauryl methacrylate, etc. The practicable example of the component B is shown by the formula 2-1.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a liquid developer for electrostatography, and more particularly to a wet type electrophotographic developer in which a toner fixed by ultraviolet irradiation is dispersed in a carrier liquid.

[Jukyo technology]

Developing means for visualizing an electrostatic latent image can be broadly classified into either a dry method or a wet method. Although both methods have their own advantages and disadvantages, the wet development method (liquid developer) is advantageous in obtaining images with good resolution and gradation. However, when a conventional liquid developer is used, it takes a long time for fixing, resulting in a slow copying speed.

In addition, conventional liquid developers do not necessarily have sufficient toner fixing power, and therefore, when such liquid developers are used for color electrophotography, the four colors of the three primary colors and black toner are unevenly layered, making it difficult to obtain faithful colors. There is also a tendency for it to be difficult to reproduce.

The present invention provides a liquid developer for electrostatography. A second object of the present invention is to provide a liquid developer that can perform not only monochrome copying but also color copying at high speed. A third object of the present invention is to provide a liquid developer that can perform contactless fixing and produce clear images.

〔composition〕

The liquid developer for static photographs according to the present invention is characterized in that an ultraviolet fixing toner containing the following (a) and (b) as main components is dispersed in an aliphatic hydrocarbon solution.

(a) Colorant (b) General formula (1) % formula % (1) [However, R1 is -H or =CH, A is -COOCnH
*H+ or -OCOCHH*n+ t (n is 6 to 2
(an integer of 0). ] A monomer or its polymer represented by the general formula (
2) % formula % (2) [However, R1 and R3 are -H or -CHI, n is 1 to 2
an integer of 0, and m is an integer of 1 to 20] or a copolymer thereof.

The present invention will be explained in more detail below, but prior to that, we will explain the reaction principle under ultraviolet irradiation by referring to "Color Materials" 48.1975, and explain how the present invention is related to the present invention from photosensitive groups currently reported. I would like to explain about "polymerizable unsaturated group".

The photopolymerizable unsaturated group is an unsaturated group that undergoes addition polymerization and polymerization by direct exposure to light or by the action of a photopolymerization initiator, and generally has the following structure.

Here, when x and x' are electron-withdrawing groups, the adjacent double bonds are activated and the polymerization rate increases. The ethylenically unsaturated group of the non-conjugated vinyl monomer is 180-200
Since it has absorption in nm wavelength, it means that 142 Kgal/mol of energy is given when ultraviolet rays of this wavelength are absorbed. Since this energy is sufficient to also break σ bonds, various radicals may be generated.

CH,=CHX (CH,=CHX)"However, the wavelength of the light absorbed by these unsaturated groups is usually in the short wavelength ultraviolet range, and the light sources used as light sources, such as high-pressure mercury lamps and xenon lamps, have short wavelengths. The emission intensity is weak in the ultraviolet region. Therefore, polymerization by direct excitation is inefficient, and polymerization using a photopolymerization initiator that easily generates free radicals (R > 1- In this case, the photopolymerization process is thought to proceed according to the following unreacted steps.

(Left below) Start Work → 11 Stop Pn・+Pm-Upper 4pn
+ Pm? "") 2 R・Pn ・+ Pm・Top
m + nt Kamibori〉■ Chain transfer Pn・+MdenPn
+P engineering/R/+M Tow P, ・Pn ・+SH bird Pn
+ S・Growth pn-+M%p-n+, S・+
M→P1 - When such a photopolymerizable unsaturated group is used as a photosensitive group, the photocuring rate of the oligomer depends on the polymerization rate of the unsaturated group. When a thin film is irradiated with light, the polymerization rate R is expressed by the following equation.

(kt=ktd+ktc) Here, work. is the incident light intensity, Q is the quantum yield of initiator radical production, ε is the extinction coefficient of the initiator, l is the thickness of the film, f is the initiator efficiency, and υ is the initiator concentration.

Therefore, the factors governing the photocuring rate of oligomers are (a) the reactivity of the initiator radicals with the monomer and the large growth rate constant kp, and (b) the initiator's ability to react at wavelengths with large radiant energy of the light source. Has a large extinction coefficient, and
Examples include a high quantum yield and a high concentration of unsaturated groups in the (/) oligomer.

In general, the reactivity of initiator radicals and monomers is such that in the transition state of their reaction, unpaired electrons are delocalized to the monomer through the conjugated system, resulting in a combination that increases the stabilization energy (ΔErs) obtained. It gets bigger. The same applies to the reactivity of propagating radicals and monomers.

From the application of this principle, in the present invention, in addition to the acrylate represented by the general formula (1) (hereinafter referred to as "component A" for convenience), ultraviolet rays are used as the inder component of the ultraviolet fixable toner. The above general formula (2) which is a curing type
A compound represented by (hereinafter sometimes referred to as "component B" for convenience) is employed.

In liquid toners, component A is present in monomeric or oligomeric form. Preferably, component A is present in oligomeric form with component B.

On the other hand, component B is also present in the liquid toner in the form of monomers or oligomers. component A and component B
Also useful are copolymers (oligomers) with

Incidentally, the component, whether monomer or oligomer, has the property of solvating with the carrier liquid (aliphatic hydrocarbon solvent). In addition, component B has the property that if it is a monomer, it will be solvated with the above-mentioned solvent, but if it is in the form of an oligomer, it will not be solvated.

Note that the ratio of component B to component A is 0.01 to 1:1.
(The weight is appropriate.

Specific examples of component A include lauryl methacrylate, lauryl acrylate, stearyl methacrylate, stearyl acrylate, 2-ethylhexyl methacrylate, 2-ethylhexyl acrylate, dodecyl methacrylate, dodecyl acrylate, hexyl methacrylate, hexyl acrylate, octyl methacrylate, and cetyl. Examples include methacrylate, cetyl acrylate, vinyl laurate, and vinyl stearate.

Specific examples of component B include the following.

OH CHs OH OH CHs OH OH OH OH CHs OH OH CM, OH Ru, Alkaline Flu, Phthalocyanine Blue, △ Spirit Black, Aniline Black, Oil Neuolette, Benzidine Yellow, Methyl Orange, Brilliant Carmine, Fast Red, Crystal Violet, etc. Examples include dyes or pigments.

A photopolymerization initiator is preferably added to the toner.

A photopolymerization initiator (photosensitizer) is a substance that is easily decomposed by ultraviolet rays and generates radicals, and is added to the binder component (component A and component B) in advance and used after development. The method is to irradiate ultraviolet rays to cause radicals from the photosensitizer to initiate polymerization.

Examples of such photosensitizers include carzenyl compounds such as diacetyl, benzyl, benzophenone, benzaldehyde, and cyclohexanone, as well as azobisisobutyronitrile, azomethane, tetramethylthiuram disulfide,
Examples include dibenzothiazolyl disulfide, carbon tetrachloride, organic peroxide, uranyl nitrate and eosin, erythrosin, neutral red, Victoria blue, and the like.

Examples of aliphatic hydrocarbons as solvents (carrier liquids) include crocin, ligroin, n-hexane, n-hebutane, n-octane, l-octane, and l-dodecane (commercial products of the above include Exxon Co., Ltd. Manufactured by Isopar H, G,
Naphtha A6; Nlupesso 100, etc.), carbon tetrachloride 1. R-fluoroethylene etc. are vignetted.

In the liquid developer according to the present invention, as described above, the inder of the toner is mainly composed of component A and component B. As the most desirable example, (a) component A
Examples include a combination of a copolymer (oligomer) of Component B and a monomer component A, and (b) a combination of a copolymer (oligomer) of Component B and a monomer component B.

"Such an oligomer can be obtained by heating and combining monomer A and monomer B in an aliphatic hydrocarbon solvent in the presence of a polymerization initiator such as benzoyl peroxide or azobisisobutyronitrile.

To prepare the liquid developer of the present invention, generally 0.00 parts of binder components (component A1 component B) are added to 1 part by weight of colorant.
Mix 5 to 5 parts by weight and add 10 parts by weight of the aliphatic hydrocarbon solvent.
In the presence of ~20 parts by weight, a concentrated toner is obtained by sufficiently dispersing it with a dispersing machine such as Attriter, Seel Mill, Kedi Mill, etc., and if necessary, this may be diluted 5 to 10 times with a similar solvent. In this case, the copolymer (oligomer) as described above and the copolymer dispersion obtained as described above can be used as they are as the solvent.

The liquid developer thus obtained is subjected to development by conventional means, and then irradiated with ultraviolet light (fixed) to form a toner image on a transfer medium such as paper.

As mentioned above, the inder component in the toner of the present invention is UV curable, so it is not exposed to UV irradiation (300
~400 nm), the toner is easily fixed.

The ultraviolet irradiation device consists of a lamp, a reflector, a lamp housing, a power supply unit, etc.

By developing and fixing (ultraviolet irradiation) using an ultraviolet curable liquid toner as in the present invention, high-speed copying of 70 or more pages per minute is possible with an A-4 size. However, if this toner contains an ultraviolet absorber, the fixing can be performed more efficiently and even higher speed copying can be performed. The addition of an ultraviolet absorber is advantageous because it also acts as an agent to prevent discoloration and fading and allows images with good light resistance to be obtained.

Specific examples of such ultraviolet absorbers include p-dimethylamino 4-enzaldehydro-dimethylaminobenzoic acid p-dimethylaminoacetophenone N-methyl N, β-chloroethylamino 4-enzaldehyde 4,4'-bis(diethylamino)benzophenone p −
Chlorobenzophenone p, p-dichlorobenzophenone Irgacure 651 (manufactured by Chino Geigy) Irgacure 184 (manufactured by Chino Geigy) Darocure-1116
(manufactured by Merck) Darocure-1173 (manufactured by Merck) 4-benzoyl diphenyl ether 4-benzoyl-4'-methyldiphenyl ether 4-
Benzoyl-4'-ethyldiphenyl ether 4-benzoyl-4'-methoxydiphenyl ether 4-benzoyl-47-chlorodiphenyl ether 4-benzoyl-4'-methyldiphenyl ether 4-. 2-benzoyldiphenylsulfide 4-benzoyl-4'-
Methyl diphenyl sulfide 4-p-) luo-4
'-Methyl diphenyl sulfide benzophenone benzoyl benzoic acid methyl ester pendiyne ethyl ether pensoin isoprobyl ether benzoin isobutyl ether penzylxanthone 2-methylthioxanthone 2-isozolobylthioxanthone 2-chlorothioxanthone counter cure DBS (manufactured by Wort Zolekinsop) )
Counter Cure PDO (made by Wort Brekinsop)
Kayacure MBP (Nippon Kayaku) Kayacure RTX (Nippon Kayaku ↓) Kayacure DITX (Nippon Kayaku) Kayacure DMB I (Nippon Kayaku) Nitsocure-EMA (Nippon Kayaku) Picure 55 (Stouffer Chemical) ) Suntray 1000 (manufactured by Sandoz), Acetocure INFP (manufactured by Aceto Chemical), Tribonal 12 (manufactured by Akzo Chemie), and DgAP (manufactured by Upjohn).

The content of ultraviolet absorber is 20% by weight based on the toner.
It is preferably 0.1 to 5% by weight. How to add UV absorber? It may be dispersed in a remer solvent, adsorbed on a pigment, or added with a photopolymerization initiator when preparing a concentrated toner.

Next, examples will be shown. All parts herein are parts by weight.

Example 1 Carzen black 300 parts (manufactured by Mitsubishi Chemical Industries, Ltd., Mitsubishi #44) Specific example of component B 5 350 parts Lauryl methacrylate (monomer) 50 parts Isopar G
Disperse 300 parts in a three-roll mill to make a concentrated type wet toner for electrostatic photography. A liquid developer was prepared by dispersing it in p.

Next, we used a plain paper copying machine manufactured by Ricoh Co., Ltd. (Ricocopy-DT-1).
After copying onto high-quality paper using the liquid developer described above, the toner was cured using two 160 W/α high-pressure mercury lamps (manufactured by Nippon Battery Co., Ltd.) at a conveyor speed of 1.7 m for 7 minutes. Obtained.

Example 2 Carn Black 200 parts (manufactured by Columbia Carzen Co., Ltd., Rapen 1225) Specific example of component B &
1/Methacrylic acid copolymer (polymerization molar ratio 9/l) Aso part Specific example of component B Boiled 2 100 parts Aituno-G
350 parts were dispersed in a ball mill to prepare a concentrated type liquid toner for electrostatic photography, and 200.9 parts of this toner was dispersed in 100 Og of IsoA-G to prepare a liquid developer.

Subsequently, a copy was obtained using the above liquid developer in the same manner as in Example 1 (however, the speed was 2.8 m and 7 minutes).

Example 3 Phthalocyanine Clean 300 parts (manufactured by Inu Nisseika Co., Ltd.) Specific example of component B 7fL6 100 parts Octyl methacrylate/acrylic acid copolymer (polymerization molar ratio 8/2) 300 parts 2-
(2'Hydroxydermethylphenyl) Pen/) IJ Azole CA External Ray Absorber〕0
．． Disperse 5 parts of Isopar H and 300 parts of it in a ball mill to make a concentrated wet toner for electrostatic photography.
A liquid developer was prepared by dispersing it in 00p.

Next, we used a Ricoh plain paper copying machine (Ricoh-DT18).
After copying onto high-quality paper using the liquid developer (00R), the toner was cured using two 16oW/α high-pressure mercury lamps (manufactured by Nippon Battery Co., Ltd.) at a conveyor speed of 4.0 m for 7 minutes to make the copies. Obtained.

Example 4 Carzen black - 300 parts (manufactured by Mitsubishi Chemical Industries, Ltd., Mitsubishi MA-11) Specific example A4 of component B
150 parts hexyl acrylate
100 parts 2-(2-hydroxy-4-methoxy-5-sulfopenzoyl) Penz 7 Lantriethanolamine [ultraviolet absorber] Disperse 300 parts of -H in 2 parts Aizuno using a ball mill to form a concentrated type liquid for electrostatic photography. A developer was created.

Subsequently, the above liquid developer was developed by a roller development method and the toner image was transferred to high-quality paper, followed by two 160 W/α high-pressure mercury lamps (manufactured by Nippon Battery Co., Ltd.) and a conveyor speed of 3.5 m 7 One layer of toner was cured for a few minutes to obtain a copy.

Examples 5 to 10 The mixtures shown in Table 1 were dispersed in a ball mill to prepare concentrated liquid developers for electrostatic photography.

Subsequently, copies were obtained in the same manner as in Example 4 using these developers. At that time, the curing speed of one layer of toner was 1.2 m 7 minutes in Example 5, 4.0 m 7 minutes in Example 6, and 3.0 m 7 minutes in Example 7. s m 7 minutes, Example 8 3.0 m 7
minutes, Example 9 4.0 m 7 minutes, Example 10 5.3
It was 7 minutes.

(Hereinafter, blank) [Effects] As described above, the present invention provides a liquid toner that has excellent fixability when irradiated with ultraviolet rays.

The use of the electrostatic photographic liquid developer of the present invention brings about the following effects.

(1) The fixing speed is fast because the fixing is completed instantaneously, and in addition, there is almost no generation of harmful vapor or odor.

(Ill) Since the non-image area is not overheated during fixing, a plastic film or the like can be used instead of paper as the image supporting member.

(Ill1 A clear image peculiar to a wet type developer is obtained, but this image is even clearer because the fixing is performed without contact.

(1v) Once fixed, the toner is not equally affected by re-irradiation with ultraviolet light, which is suitable for obtaining color copies.

Claims (1)

[Claims] 1. A liquid developer for electrostatic photography, characterized in that an ultraviolet fixing toner containing the following (a) and (b) as main components is dispersed in an aliphatic hydrocarbon solvent. agent. (a) Colorant (b) General formula (1) ▲There are mathematical formulas, chemical formulas, tables, etc.▼…………(1) [However, R^1 is -H or -CH_3, A is -COOC
_nH_2_n_+_1 or -OCOC_nH_2_n
___+_1 (n is an integer from 6 to 20). ] A monomer or its polymer represented by general formula (2) ▲There are mathematical formulas, chemical formulas, tables, etc.▼ ▲There are mathematical formulas, chemical formulas, tables, etc.▼……………………(2) [However, R^ 2 and R^3 are -H or -CH_3, n is an integer of 1 to 20, and m is an integer of 1 to 20. ] A composition containing a monomer or a polymer thereof, or a copolymer thereof. 2. Claim 1 in which the toner contains an ultraviolet absorber
Liquid developer described in section.