JPH03287174A - Electrophotographic wet toner - Google Patents

Abstract

PURPOSE:To facilitate printing by dispersing resin particles comprising as photochromic material and a thermoplastic resin into an insulating liquid to form the wet toner. CONSTITUTION:The electrophotographic wet toner is obtained by mixing the photochromic material and the thermoplastic resin, heat melting the mixture in a solvent, then, cooling it while stirring it to precipitate the resin particles, replacing the solvent by the insulating liquid by decantaion or the like, and dispersing the resin particles to which the photochromic material is attached into the insulating liquid, thus permitting the obtained electrophotographic wet toner to be easily attached to a dielectric material, such as a planographic plate, paper, plastics, and the like.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a liquid toner for electrophotography containing a photochromic material, particularly for electrophotography that enables printing suitable for anti-counterfeiting, entertainment, and educational purposes. Regarding liquid toner.

[Conventional technology]

A method of forming image areas on a lithographic printing plate using an electrophotographic method is used in the field of light printing, but this method generally involves applying photoconductive zinc oxide powder to the surface of conductive treated paper along with a binder resin. This is a method of obtaining lithographic prints by negatively charging the coated zinc oxide master paper, exposing it imagewise, developing it with an electrophotographic toner, fixing it, and then hydrophilizing the image area. However, although conventional liquid toners for electrophotography to which colorants are added are known, liquid toners for electrophotography that have a photochromic material that is effective as a means for preventing counterfeiting of printed matter have not been provided.

On the other hand, photochromic materials that change color when exposed to light,
This type of printing plate, paper, plastic, etc. is generally adhered to dielectric materials such as paper, plastic, etc. by letterpress, lithography, intaglio printing, etc. using photochromic ink, but since the photochromic ink itself uses a solvent, it is drafty. There are situations in which images containing photochromic materials cannot be obtained with simple operations.

[Problem to be solved by the invention]

An object of the present invention is to provide a liquid toner for electrophotography that allows a photochromic material to be easily attached to a dielectric material such as a lithographic printing plate, paper, or plastic.

[Means to solve the problem]

The electrophotographic liquid toner of the present invention is an electrophotographic liquid toner in which particles are dispersed in an electrically insulating liquid.
The particles are characterized in that they are made of a photochromic material and a thermoplastic resin.

The particles forming the liquid toner for electrophotography of the present invention are composed of a photochromic material and a thermoplastic resin.

First of all, as a photochromic material, for example, JP-A-55
The following spiropyran-based compound disclosed in Publication No. 149812, Photo-H dispersed in a polymeric compound having an acid group (wherein Rd and R" represent a hydrogen atom, a halogen atom, an alkyl group, or an alkoxy group) ) In addition, the special public
The following spironaphthoxazine compounds described in JP-A-28892 (in the formula, Ra is a hydrogen atom or a halogen atom, Rb is an alkyl group, and Rc is a hydrogen atom or an alkoxy group), and JP-A-50-28824 The following spiropyran compound described in JP-A No. 2003-111000 was mixed with alcoholic water (wherein, Rf represents a hydrogen atom, a halogen atom, a cyano group, an alkyl group having 1 to 8 carbon atoms, or an alkoxy group). 63-24245, each having a heterocyclic group at the 1st and 2nd positions that changes its optical properties by cyclizing to form a hexadiene ring upon irradiation with light, and the other one Ethylene derivatives in which the positions and the 2-position are bonded to each other to form a ring, dichenylmaleic anhydride derivatives, etc. can be used.

Specifically, for example, 1,3.3-)! J Methyl 6-nitro-8-methoxyspiroindoline-2゜2'-benzopyran, 6'-nitro-1-(meth)acryloxyethyl-3,3-dimethylindolinospirobenzopyran,
8'-(meth)acryloxymethyl-6'-nitro 1
．． 3.3-) Limethylindolinospirobenzopyran,
Examples include 6'nitro-1-(meth)acrylamidoethyl-3°3-dimethylindolinospilobenzopyran.

Next, as the thermoplastic resin, it is preferable to use a solvent-soluble and temperature-dependent resin, such as polyvinyl chloride, ethylene-vinyl acetate copolymer, polystyrene, ABS resin, methacrylic resin, ionomer, polyamide, polycarbonate, Polyphenylene oxide, polysulfone, urea resin, polyester resin, cellulose acetate,
Partially saponified products of silicone resin, urethane resin, polyethylene, alkyd resin, modified polyethylene, ethylene-acrylic acid copolymer, ethylene-vinyl acetate copolymer,
Examples include resins called "hard resins" such as ethylene-acrylic ester copolymers, rosins and derivatives, petroleum-based hydrocarbon resins, and terpene-based resins, and one or two of these resins. It is best to use a mixture of two or more species. Particularly in the present invention, among the above thermoplastic resins, it is preferable to use an olefin resin having a carboxyl group or an ester group.

To form the liquid toner for electrophotography of the present invention, the photochromic material and the thermoplastic resin are heated and dissolved in a solvent that dissolves them together, and the photochromic material and the thermoplastic resin are cooled while stirring to precipitate resin particles. can be made into resin particles in a state where the particles are bound together.

Alternatively, a photochromic material and a thermoplastic resin are mixed, heated and dissolved in a solvent, cooled while stirring to precipitate resin particles, and then the solvent is replaced with an electrically insulating fluid by a method such as decantation to form a photochromic material. It is possible to disperse resin particles binding materials into an electrically insulating fluid.

The photochromic material is preferably used in a proportion of at least 10% by weight or more based on the thermoplastic resin. If the proportion of the photochromic material used is less than 10% by weight, the resulting toner will not exhibit sufficient photochromic properties.

Thermoplastic resin is an important component that forms toner particles, and also acts as a binder for photochromic material. The photochromic material and thermoplastic resin are heated and dissolved in a solvent, and the resin particles are cooled while stirring. When precipitated, the photochromic material becomes resin particles bound to the thermoplastic resin.

As the solvent, known solvents that dissolve photochromic materials and thermoplastic resins can be used, such as liquid n-paraffinic hydrocarbons, 15O-paraffinic hydrocarbons, or mixtures thereof, acetone, ketones such as methyl ethyl ketone, Alcohols such as isopropyl alcohol, aromatic hydrocarbons such as toluene, halogenated aliphatic hydrocarbons, halogenated aromatic hydrocarbons, siloxane oil, etc., and mixed solvents of combinations of these solvents are preferably used. be able to.

In addition, as electrically insulating fluids, thermoplastic resins and photochromic materials are used to prevent dissolution of foreign substances as much as possible, that is, to maintain electrical insulation and prevent developer deterioration. electrically insulating liquids with relatively low dissolving power, especially aliphatic hydrocarbons, e.g.
So- or n-paraffinic hydrocarbons and freon-based hydrocarbons are preferably used, and the is○-paraffinic hydrocarbons include Isopar (manufactured by Exxon Chemical Co.), Isododecane (manufactured by British Petroleum), 1, and P-solvent (Idemitsu Petroleum). (manufactured by Kagaku Co., Ltd.), isooctane, etc. N-paraffinic hydrocarbons include n-hexane, n-hebutane, n-octane, etc., as well as halogenated hydrocarbons such as carbon tetrachloride, ligroin, cyclohexane, etc. In particular, Isopar (manufactured by Exxon Chemical), which does not dissolve photochromic materials, 1. P-solvent (manufactured by Idemitsu Petrochemical Co., Ltd.) etc. can be preferably used.

Further, a charge control agent may be added to the liquid toner for electrophotography of the present invention in order to impart charge to the resin particles.

Charge control agents that can be used include manganese naphthenate,
Calcium naphthenate, zirconium naphthenate, cobalt naphthenate, iron naphthenate, nickel naphthenate,
Chromium naphthenate, zinc naphthenate, magnesium naphthenate, manganese naphthenate, calcium octylate,
Zirconium octylate, iron octylate, lead octylate, cobalt octylate, nickel octylate, chromium octylate, zinc octylate, magnesium octylate,
Metal soaps such as manganese dodecylate, calcium dodecylate, zirconium dodecylate, iron dodecylate, lead dodecylate, cobalt dodecylate, nickel dodecylate, chromium dodecylate, zinc dodecylate, magnesium dodecylate, calcium dodecylbenzenesulfonate, Examples include alkylbenzene sulfonates such as calcium dodecylbenzenesulfonate and barium dodecylbenzenesulfonate, phospholipids such as lecithin and sehalin, organic amines such as n-decylamine, and other known charge control agents. It can be used if The amount of charge control agent added is
It can be used in an amount of 0.01% to 50% by weight in the solvent during heating and dissolution.

Further, a coloring agent component may be added to the electrophotographic liquid toner of the present invention as necessary to cause color mixing with a photochromic material.

When an electrophotographic photoreceptor is developed using the electrophotographic liquid toner prepared in this way, the resin particles in the liquid developer are positively charged, and the electrophotographic photoreceptor used with a negative charge is It gives a positive image on a body, such as a zinc oxide/resin photoreceptor, and can be developed in reverse if it has the same polarity.

The wet toner of the present invention can of course be applied to an insulating transfer target such as paper by a normal transfer method, that is, electric field transfer such as corona transfer, but it can also be applied to an electrically conductive transfer target such as metal. In contrast, it can be efficiently transferred from the surface of an electrophotographic photoreceptor by a pressure transfer method.

Transfer methods include electrostatic transfer method and physical transfer method.
The physical transfer method transfers the toner image onto a metal surface by placing the toner image in close contact with a transfer object coated with a pressure-sensitive adhesive on one side, applying pressure with a soft roller, and peeling it off. However, transfer can be performed regardless of the electrical properties of the object to be transferred, and generally known electrophotographic photoreceptors can be used for this purpose, but it is more preferable to When an electrophotographic photoreceptor having an easily peelable layer is used, pressure transfer can be performed directly onto an object to be transferred.

The liquid toner of the present invention can be made into a toner suitable for a physical transfer method by using an olefin resin having a carboxyl group or an ester group as resin particles, and can be used repeatedly on an electrophotographic photoreceptor. When using a photoconductor, it is necessary to efficiently transfer the toner on a photoreceptor to a transfer target, but by using the toner of the present invention, an image with excellent printing durability can be formed in the lithographic printing plate layer. can do.

[Action and effect of invention]

The liquid toner for electrophotography of the present invention is formed by dispersing resin particles made of a photochromic material and a thermoplastic resin in an electrically insulating liquid, and therefore does not require equipment such as a draft to produce an image containing the photochromic material. It can be obtained by a simple operation without having to do anything, and it is possible to easily produce prints suitable for anti-counterfeiting, entertainment, and educational purposes.

The present invention will be explained below with reference to Examples.

[Example 1] 1,3.3-)rifthyl-6-nitro-8-methoxyspiroindoline-2,2'-benzopyran 1 wt%
, Acrylic resin 25wt% Cellulose acetate 2wt%
, 12.5 g of a 72 wt% solution of methyl ethyl ketone/toluene was added to 10 wt% of toluene.
Dilute with 0 g and warm to 50°C.

Next, 522 g of Isopar H was added little by little to this liquid and stirred for 30 minutes. After cooling and returning to room temperature, decantation was performed with Isopar H seven times.

With the resin particles dispersed in Isopar H, 9.91 g of 10% cobalt naphthenate/Isopar H solution was added to 91.5 g of this dispersion, and further Isopar H was added to make a total of 500 g, and the electrophotography of the present invention was prepared. A liquid toner was prepared.

30ml of this liquid toner for electrophotography was placed in an electrolytic cell with an interval of ICm, and brass electrodes (5cm x 6cm) in the electrolytic cell were placed.
cm), and the amount of charge on the toner was measured with an applied voltage of 1000V. The current changes with time at this time are shown in Table 1 below.

2 Obtained.

[Example 2] Zinc oxide paper (Fuji Photo Film ■) was used as an electrostatic printing master, and after being charged to -to ov to -700V, patterning exposure was carried out to print the electrophotographic wet type prepared in Example 1 above. It was developed with toner and dried to fix the toner image.

When the toner image was irradiated with UV light, the color changed from pink to bluish-purple, which confirmed that the toner image had photochromic properties.

Claims (1)

[Claims] (1) An electrophotographic liquid toner comprising particles dispersed in an electrically insulating liquid, the particles comprising a photochromic material and a thermoplastic resin.