CS238667B1 - Electrographic liquid developer - Google Patents

Abstract

Liquid electrographic developer for positive imaging based on iaoporafinlic petroleum hydrocarbons. For the preparation of the developer, it is possible to use inexpensive non-standard raw materials, e.g. rubber carbon black. The electrographic developer contains in the form of a concentrate 2 to 30% by weight of pigment, 25 to 95% by weight of binders and surfactants, 1.5 to 50% by weight of solvent and 0» 01 to 3% by weight of 2>6·41'· tert.butyl-4-methylphenol. A list of substances that can be used for the preparation as pigments, binders, surfactants and solvents is given below. The electrographic developer can be used for direct development of electrographic papers coated with zinc oxide and for developing dielectric materials

Description

The invention does not pertain to electrographic liquid positive developers based on laoporaffinic petroleum hydrocarbons. The developer allows the use of low-quality raw materials in the case of high mobility in concentrated and diluted fatigue.

A liquid developer for use in electrography, ascribed to the term, is commonly used for electrophoretics to induce latent electrostatic defenses resulting from conventional photopolymers layers. The most widely used system is a zinc-coated mat with zinc zinc with suitable binder and áalilml additives. The process of processing is based on the surface charge of this material to a potential of about 500 V, followed by exposure and development of a latent electrostatic image by a suitably undiluted developer. A positive electrographic developer is usually used for direct copying of originals. In the case of copying negative copies, for example * when reproducing back from negative microfilms * or microfiche, the developer negative is used to evoke the image, resulting in positive copies. These developers, especially the positive developers, are faced with dreamlike demands regarding their image reproduction quality and stability. In particular, a high dispersion stability with respect to concentration is required, furthermore suitable electrophoretic properties, in particular linear dependence carried by surface potential and resulting anonalt, good adhesion of dye particles to the paper surface, high image densities, minimum tendency to various printing defects, perfect sharpness of contours, possibility of using different types of * capsules for dilution etc.

These developers are essentially very fine dispersions of the organic non-inorganic pigment in a non-polar environment. The pigments used have to satisfy the high demands of the surface electrostatic and electroforethetic surfactants in relation to the dispersion medium. Commonly used are carbon black, iron oxides, nigrosine dyes, phthalocyanines and the like. As the surfactant and binder, various types of vegetable oils are used, alkyd resin, bridging acids such as oleic acid, rosin rosin and its esters, metal salts of organic acids, such as naphthenates and ectoates of cobalt, manganese and lead, mineral oils, etc. The preparation of the developer consists in intensive dispersion of the pigment in a non-polar environment with the presence of binder or surface active agents. The purpose is primarily to accelerate the diapergation and to increase the stability of the dispersion by providing a protective colloidal envelope around the pigment particle in the form of an electric diffusion layer. Important in this case is the soft and electrical solid state protection of the pigment particle. The process must result in a fine dispersion having a particle size of the solid phase in the range of 10 to 10 µm, which is stable to external influences, the particles having suitable and uniform electrical properties.

The disadvantage of the existing electrographic developer composition systems used is, in particular, that they do not completely prevent the sedimentation of the formed dispersion and the coagulation of the particles either in the original dispersion or in the sediment, the resuspended or partially cogulated dispersion has already changed properties. The reason is usually the enlargement of the original particles by shifts in the electric diffusion layer, respectively. uncontrolled changes due to electric field during self-induction. These changes are very significant, for example, when using lower-quality grain, i.e., where their particle size may fluctuate, or where carbon black is produced for other purposes, such as rubber soot. These problems may increase for a longer period when using low-quality developing fluids containing complex organic substances to accelerate the oxidation of the developer components. There are then various defects due to natural aging, or 1 during processing, when these defects may occur / eg. by decreasing the contrast by decreasing the value of the maximum blackening, creating blurred lines of litter. Sometimes it is difficult to control the surface charge of particles, which is related to the achieved value of maximum blackening. In extreme cases, solid phase precipitation may occur and the developer virtually loses its effect.

These disadvantages are eliminated in the electrographic liquid developer according to the invention, characterized in that it contains 2 to 30% by weight of pigment, 25 to 95% by weight of binders and surfactants, 1.5 to 50% by weight of a binder and 0.01 to 30% by weight. up to 3%

23 * 667 by weight of 2,1-di-tert-butyl-4-methylphenol. For its own use, the concentrate is diluted with iaoparofinil oil fraction.

What pigments can be used for all types of suction, especially carbon black produced on a large scale for the rubber industry. Among the organic pigments, nigre sin dd, phthalocyanine, indanthrefine, triarylmethane, triphenylmethene dyes can be advantageously used. Anerganic pigments are barium sulphate, iron oxides, zinc oxide, titanium dioxide, cadmium sulfur, silicon oxides and the like.

Which soybeans and surfactants are used by the vegetable oils, such as soybean, linseed, castor and talc, fatty acids such as alejevd, llnolic, linolenic, aliphatic acids above Cg, seleganic acids with heavy metals such as naphthenates, oleate or · cobalt and manganese lead stearates, resp. calcium, C ₂₀ to C ₁₈ mineral oils, alkyd resins and generally pelyesters, low molecular weight polystyrene, low molecular weight polyethylene, styrene-acrylate copolymers, acrylate copolymers, eeluloay polymers, derivatives, copolymers of vinyl toluene and butadiene, waxes and the like.

As solvent, isoparaffinic oil fractions with a distillation range of 130 to 206 ° C with possible admixtures of ecycloparaffins, aromatic hydrocarbons, alcohols up to Cg, etc. are used.

The advantages of the electrographic developer according to the invention consist in the possibility of using lower quality and less standard raw materials such as rubber soot for its own preparation, and in the possibility of using lower quality developing liquids based on isoparaffinic petroleum fractions containing oxidation activating components of the developer. Developers thus prepared are generally more stable in their concentrated and diluted form.

Example

Prepare a mixture of 10 ml of isoparaffinic oil fraction (deat. Range 140-180 ° C), 20 ml of toluene, 12 g of oleic acid, 0.4 g of rosin ester, 7 g of cobalt naphthenates (10% solution in toluene), 7 g of brilliant black £, 7 g of rubber black (Higros type), 6 g of linseed oil (moderately thickened) and 1.2 g of 2,6-di-tert-butyl-4-ethylphenol.

This mixture ae is dispersed in a pearl disperser from cooling for 30 min and then 110 g of SAK 30 mineral oil and 11 g of linseed oil (medium thickened) are added.

After mixing, the ee concentrate is decanted from the beads and for further use ee is diluted with isoparaffinic oil fractions in a ratio of 3 to 5 ml of concentrate to 1 l of 1-paraffinic fraction. The developer thus prepared is used to induce exposed materials based on zinc oxide.

Following the same procedure, an electrographic pump was prepared which did not contain 2,6-di-tert-butyl 4-methylphenol. The control developer thus prepared had, under various processing conditions, a stability and anisone of 40 to 60% against the developer shown in the above example.

The electrographic developer of the invention can be used to generate electrographic and dielectric materials.

Claims (4)

1. Electrographic liquid discharge, indicated by t1, la, contains in the concentrate farm 2 to 3% hmetnaatl pigment, 25 to 95% hnatnaatl beverages and sprays active substances, 1.5 to 5% by weight of the retentulant and # 1 to 3% by weight of 2, .alpha.-tert-butyl-4-methylphenal. 2. Electrographic liquid discharge fell to snake 1, invented by the fact that both pigments contain aase alley retort or channel, alone or in blends organic pigments jaka nigrasins, laxanthanes, triarylmethanes, trlphenylmethanes, barium sulphate, gelatin oxides , titanium dioxide, cadmium moss and silicon oxides. 3. Klektrsgraflckd liquid pad of padle badu 1 · 2, characterized in that both pea and spruce-active substances contain plant alleyes, eg soybean, linseed, diving skies tar lava alley, maatma acids, such as alley kyaelina, llnelanavá, aliphatic acid, NAA Cg salts arganiekých acids and heavy coffee yak naphthenate aleáty-and Ateara Rb, Ca, and Hn optionally Ca, mineral alley C _GI to C? g alkydavá resin and palyestery, nískamalekm & .arm pelyatyren, nízkemalekuldrní ethylene paleylene, acryldtd polymers, cellulase polymers and derivatives; 4. Electragraphic liquid padle pad 1 to 3, characterized in that the yeast contains isoparaffinic fractions of petroleum with a distillation range of 130 to 200 ° C, aromatic hydrocarbons, yen derivatives of bensene and possible alcohols da Cj alone or in amasses.