JPH03123364A - Toner for liquid development - Google Patents

Abstract

PURPOSE:To improve the adhesiveness of the toner to a medium to be transferred by using a microcapsulated toner contg. the component which can be cured by UV rays and irradiating the toner with UV rays after transferring the same onto a medium to be transferred. CONSTITUTION:This toner 11 is formed by packing a core material 12 contg. at least a pigment, polymerizable monomer or resin crosslinkable by UV rays and polymn. initiator into a wall film 13 and microcapsulating the same. This toner 11 is transferred onto the medium to be transferred and a desired pressure is applied thereon to expose the core material 12 onto the medium; thereafter, the toner is irradiated with the UV rays to cure the prescribed components. The toner is preferably used for an image recorder which utilizes photoelectrophoresis.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application J] The present invention generally relates to a toner for liquid development used in printing apparatuses using electrophotographic liquid development.

For more details, see Image Recording Device Using Photoelectrophoresis [Prior Art 1] For a comprehensive and detailed explanation of what is generally called a photoelectrophoretic image forming method, please refer to the following article. l38-22645
(Applied by Rank Xerox), Japanese Patent Publication No. 43-2178
1 (Xerox Corporation application) or U.S. Patent No. 33839
No. 93, No. 3384488, No. 3384565, and No. 3384566 (filed by Xerox Corporation).

In other words, if we explain the developing method using toner in general,
The main components consist of photoconductive toner and a pair of electrodes.
A photoconductive toner is located between the electrodes and is dispersed in an organic solvent. In an organic solvent in a dark place, the photoconductive toner is an insulating substance and is relatively easily charged. When an electric field is applied between the electrodes, the photoconductive toner is electrophoretically attracted to the electrode with the opposite polarity to that charged on the toner. When exposed to the latent image, the photoconductive toner in the exposed area becomes conductive and is given or given a charge by an electrode reaction with the electrostatically attached electrode, electrophoresing to the opposite electrode and returning to the original electrode. A positive image is formed.

[Problem to be solved by the invention M1 As mentioned above, in the image recording method using the conventional photoelectrophoresis method, when the toner that has been rearranged to the inverted t4 pole is directly heated and melted to make a copy (Electrofax method) and the adhesion When transferring the toner onto paper and heating and melting it, CX
erox method).

The fixing of the toner used in such technology is carried out by adhesion of the toner by heat fusing or heat removal of the carrier.

However, when applied to printing plates, printing screens, printers, and copying machines using the above-mentioned method, for example, there is a problem with the adhesiveness of the photoconductive toner.

That is, in any case, since the photoconductive toner itself does not have a fixing component, a large amount of physical energy must be applied to fix it.

In addition, conventional photoconductive toners are used in printing plates, printing screens, printers, and copiers that require precise images and characters because they must be soaked into non-transfer paper using strong mechanical energy, i.e., pressure. There was a gap.

Therefore, it is an object of the present invention to increase the adhesion of photoconductive toner to a transfer medium.

[Means for Solving the Problems 1] The liquid developing toner according to the present invention includes at least a pigment,
It is characterized by microcapsulating a polymerizable monomer or an ultraviolet crosslinking resin and a polymerization initiator, and irradiating ultraviolet light after transferring the microcapsules onto a transfer medium to cause the core substance of the microcapsules to undergo a polymerization or crosslinking reaction. shall be.

Further, it is characterized in that it can be applied to an image recording device using photoelectrophoresis.

[Operation] The operation of the above configuration of the present invention will be explained. FIG. 1 shows the main components of the developer of the present invention. In the figure, 11 is a photoconductive toner, and 12 is a core material of microcapsules containing a polymerizable monomer containing one or more vinyl groups or a resin crosslinked by ultraviolet rays (hereinafter referred to as an ultraviolet curable resin) and a polymerization initiator. It is. Further, 13 is the wall membrane of the microcapsule. The developing solution for an image forming method using photoelectrophoresis is usually an insulating solvent that is liquid at room temperature, such as normal paraffin oil, and a toner that exhibits photoconductivity (
(hereinafter referred to as toner) is used.

The developing solution for image forming methods using photoelectrophoresis usually uses an insulating solvent that is liquid at room temperature, such as normal paraffin oil, and a toner that exhibits photoconductivity (hereinafter referred to as toner). .

In contrast, in the present invention, an ultraviolet curable resin, a polymerization initiator, and a toner exhibiting photoconductivity are dispersed as microcapsules in an insulating solvent. During development using the liquid developing toner of the present invention (hereinafter referred to as a microcapsule), the toner can be transferred onto a transfer medium in exactly the same manner as a normal liquid developing method. The difference in function here is that when development is performed using a conventional developer, physical fixing such as heat or pressure is required to enhance the adhesion effect to the transfer medium.

In the present invention, when the transfer is completed, by applying some pressure to the microcapsule, the ultraviolet curing resin and polymerization initiator in the microcapsule are exposed on the transfer medium, and when the toner is irradiated with ultraviolet rays, the toner is cured. The reaction begins. Since the curing reaction of the toner proceeds while the ultraviolet curable resin has penetrated into the transfer medium, it is as if the toner and the transfer medium have undergone a crosslinking reaction and the adhesive strength has increased.

In addition, once the curing reaction of the toner begins, the curing reaction of the toner increases as a chain reaction in such a way that the insulating solvent is surrounded by the ultraviolet curing resin. There is no need to extend the drying time until it evaporates.

In other words, in the present invention, the ultraviolet curing resin of the microcapsules increases the adhesive strength between the toner and the transfer paper, and furthermore, it is possible to improve the printing speed by omitting the drying step.

(Example 1 First, a developer that can be used in the present invention will be specifically explained. Photoconductive toner particles that can be used in the present invention include, for example, phthalocyanine pigments such as copper phthalocyanine, bisimidole perylene pigments, etc.) , anthraquinone pigments such as flavanthrene, azo dyes such as calcium lake red, Diana blue-naphthol red,
Quinacridone pigments, dioxazine pigments, etc. can be used. In addition, inorganic photoconductive substances such as zinc oxide and titanium oxide, fluorescein, rose bengal, bromoflavin, malachite green, methylene blue, eosin, erythrosin, rhodamine B1, bromophenol, brilliant blue, phloxine, crystal biont, xanthine, and phthalein. It can also be used alone or in combination with dyes such as triphenylmethane, azo, and anthraquinone. In addition, surface modification etc. can be performed to impart various properties.

Vehicle resins for UV curing include unsaturated polymers such as acrylic polymers, polyvinyl chloride, chlorinated polybutadiene, and other resins dissolved in polyfunctional vinyl such as acrylic monomers, or acetylene unsaturated groups, vinyl Examples include resins in which thioether groups, norbornyl groups, etc. are grafted onto resins. Examples of other vehicle resins include prepolymers with unsaturated bonds in the main chain or prepolymers with active unsaturated groups in side chains or terminals. Examples of the former include a system of maleic anhydride type unsaturated polystyrene and styrene, silicone-modified, urethane-modified, acrylic urethane-modified, etc., or polyester, acrylic resin, and epoxy resin into which a maleic group is introduced. An example of the latter is one having an active group at the end or side chain of the main polymer, such as an acrylic ester prepolymer having two or more acryloyl groups in one molecule.

Other methods utilize the ring-opening reaction of addition polymerization type resins, such as thiol/polyene type resins, and photo-opening type resins, such as epoxy resins.

In addition, the most effective way to apply the present invention is to use a combination of addition-polymerizable monomers, prepolymers, photopolymerization initiators, and photosensitizers for ultraviolet curing ink vehicles, especially those containing acrylic acid as the main component. Acrylic monomer prepolymers containing methacrylate, itaconic acid, and itaconic acid are effective.

Examples of acrylic prepolymers include polyol acrylate, polyester acrylate, epoxy acrylate, urethane acrylate, polyether acrylate, acrylate alkyd, polyacetal acrylate, silicone acrylate, melamine acrylate, and other 7 acrylates. Typical prepolymers include: Polyol acrylates include pentaerythritol triacrylate, pentaerythritol tetraacrylate, diventaerythritol hexaacrylate, ditrimethylolpropane tetraacrylate, and epoxy acrylates include bisphenol A
Examples include glycidyl ether acrylate, modified bisphenol A epoxy acrylate, epoxidized drying oil acrylate, aliphatic eboxy acrylate, etc. Urethane acrylates include polyacrylate carbamate, hexanediol TD, and reaction products of 2- and droxyethyl acrylate. Examples include. Further, it is preferable to add a reactive monomer together with the prepolymer for crosslinking and addition polymerization reactions.

Examples include cyclohexyl acrylate, benzyl acrylate, carpitol acrylate, 2-ethylhexyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxyglobyl acrylate, hydroxypropyl methacrylate, N-methylol acrylamide, N-di Acetone acrylamide, styrene, vinyl acetate, N-vinylpyrrolidone, ethylene glycol diacrylate, diethylene glycol diacrylate, triethylene glycol diacrylate, polyethylene glycol diacrylate, butylene gelkol diacrylate, neopentyl gelkol diacrylate, 1. 4-butadiol diacrylate, 1,
Examples include 6-hexanediol diacrylate and trimethylolpropane triacrylate. The ultraviolet curable resin used in the present invention may be selected from the above resins alone or in combination. A polymerization initiator is also used in this invention. Generally, radical type and hydrogen abstraction type can be used. Examples include benzoin ethyl isobutyl benzoin ether, benzoin ethyl ether, benzoin methyl ether, and the like.

Further, the microencapsulation method for microencapsulating the above-mentioned ultraviolet curable resin, polymerization initiator resin, and toner includes a coacervation method, an 1n-situ method, an interfacial polymerization method, a phase separation method, an in-liquid curing coating method, A spray drying method, an Orenis method, etc. are used, and the selection of the wall coating agent is carried out depending on the properties of the ultraviolet curable resin and the polymerization initiator, which are the core materials of the microcapsules, and the encapsulation characteristics.

All substances can be used as wall materials for microcapsules, but preferred examples include polyvinyl acetate, polyvinyl acetate/cellulose acetate butyrate, styrene-maleic acid copolymer, benzyl sulfose, ethyl cellulose, and polyethylene. , polystyrene, natural rubber,
Nitrocellulose, ketone resin, polymethyl methacrylate, polyamide resin, acrylonitrostyrene copolymer, vinylidene chloride-acrylonitrile copolymer, epoxy resin, polyvinyl formal, hydroxypropyl cellulose, vinyl chloride-vinyl acetate copolymer,
Polyvinyl chloride, shellac, vinyl chloride-vinyl acetate copolymer, polyester, polycarbonate, polyacrylate ester, cellulose acetate propionate, cellulose acetate butyrate, polyvinylpyrrolidone, vinyl chloride butyl acetate copolymer, hydroxyglobil methylcellulose lid Examples include polyester, polyurethane, polyurea, gelatin, waxes, and polysaccharide resin.

Further, in order to improve the dispersibility of the photoconductive image-forming particles in the thermoplastic material and the uniformity of charging characteristics, a suitable charge control agent, dispersant, etc. may be included in the developer solution.

Next, the microencapsulated product of the present invention was produced using an interfacial polymerization method as follows.

1. In a dark room, add 5 g of bisphenol A prepolymer, 25 g of vinyl monomer (pentaerythritol tetraacrylate), 0.1 g of photopolymerization initiator, and 5 g of vanadyl phthalocyanine (manufactured by Kodak), and place on a hot plate (60"c). ).

2. Next, place in another reaction system, weigh out 100 g of a 5% aqueous solution of gum arabic as an emulsion stabilizer, and heat 5 g of the curing agent on a hot plate.

The solution prepared in step 2 above is gradually added to the solution prepared in step 1 above while stirring with a homomixer, and emulsified.

When the average flow diameter of the emulsion reaches 2 to 3 μm, the homomixer is replaced with a normal stirring device to produce microcapsules.

The developer was prepared as follows. Next, the prepared microcapsules were spray-dried to completely remove water, and then redispersed in saturated hydrocarbon oil (Isopar G Exxon Chemical) to obtain a developer.

Next, the composition of the developer used in a comparative example of the present invention will be shown. Take 40g of the following mixture into a sample bottle and add 1 glass pea.
A developing solution containing photoconductive image forming particles having a maximum particle size of 1 μm or less was prepared by dispersing 10 g of the sample in a paint shaker for 10 hours.

Composition Vanadyl phthalocyanine 2wt% (manufactured by Kodak) Tsurusperse 17000 0.2wt% (manufactured by ICI) Isopar G (manufactured by Exxon Chemical Co., Ltd.) 97.8wt% A developer according to the present invention and a developer having the composition shown in the comparative example were used. hand,
A development experiment was conducted using the simple experimental system shown in FIG.

First, in this embodiment, an electric field is applied to a beaker 25 containing a developer according to the present invention in a dark room to cause toner to adhere to a transparent electrode 21. At this time, the photoconductive toner of the embodiment has a negative charge. In a simple experimental system, the thickness of the plate is 2 mm.
An image forming particle receiving electrode 23 is fixed via a polyimide spacer 22. Reference numeral 23 denotes an image-forming particle receiving electrode with silicone rubber pasted on its surface in order to improve the transferability of the transferred material to the transfer paper for evaluation described later.

The positive terminal of a power source 26 is connected to the electrode 23. In this simple experimental system, a voltage of 2000 V was applied between each electrode, and at the same time exposure light 27 was irradiated from the transparent electrode 21 side for 2 seconds to form an image.

Next, for the comparative example, development was performed in the same manner as in the present example to form an image on the image forming particle receiving electrode.

Next, an image forming particle receiving electrode developed using the developer according to the present invention and an image forming particle receiving electrode developed according to a comparative example were taken out from the simple experiment system, and the respective electrodes were pressure-transferred onto copy paper. In the example, ultraviolet irradiation was performed for 5 seconds. Further, in the comparative example, after being left on a hot plate for 10 seconds to fix, pressing force was applied using a rubbing tester to compare the adhesive strength of the example and the comparative example.

As a result, the transfer material prepared using the liquid developing toner of the present invention did not peel off even under a pressure of 100 g when irradiated with ultraviolet rays. In the comparative example, it was peeled off with a pressure of 20 g. In addition, in Comparative Examples, the heating time until the transfer material dries and the strength in the peel test shows the highest value is 100 seconds, and 30 seconds.
It was peeled off with a pressure of g.

] Effect of the invention 1 As described above, according to the present invention, in an image forming method using photoelectrophoresis, since an ultraviolet curable resin is added to the developer and irradiated with ultraviolet rays, It was possible to increase the adhesion strength of the toner on the medium. Further, as shown in the examples, in the case of the conventional method, a fixing time of 100 seconds was required to improve the adhesion of the transferred material to the transfer medium, and the pressing force was 30 g or less.

From the above, the effect of the present invention is that it is possible to supply a toner for liquid development that has a short fixing time and high fixing strength.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing the structure of the developer of the present invention. FIG. 2 is a schematic diagram showing an experimental example. that's all

Claims (2)

[Claims] (1) Microcapsule at least a pigment, a polymerizable monomer or a UV crosslinking resin, and a polymerization initiator,
A toner for liquid development, characterized in that after the microcapsules are transferred onto a transfer medium, ultraviolet rays are irradiated to cause the core substance of the microcapsules to undergo a polymerization or crosslinking reaction. (2) The liquid developing toner according to claim 1, characterized in that it is used in an image recording device that utilizes photoelectrophoresis.