DE1930195A1 - Liquid developer for electrostatic latent images - Google Patents

Description

Kabushiki Kaisha Ricoh

Tokyo. Japan f J.

Liquid developer for electrostatic latent images

The invention relates to a liquid developer for electrostatic Latent images.

For the visualization of an electrostatic latent image produced on a carrier by the wet process, a liquid developer is generally used _, which is obtained by dispersing colored particles, e.g. carbon black, in a carrier liquid with a high specific insulation resistance and low dielectric constant and adding a suitable amount of a polarity regulator manufactures "

A hydrocarbon solvent is used almost exclusively as a carrier liquid, and only sometimes such a solvent from hydrogen halides. Both types are disadvantageous in that the former is flammable and the latter is poisonous and moreover is expensive

Since these disadvantages also apply to the liquid developers prepared with them, one has to improve the carrier liquid endeavored and already announced related suggestions. For example, in Japanese Patent Specification 266 4o4 describes a liquid developer of the W / O emulsion type, which is obtained in such a way that it is initially immersed in a carrier liquid with a high specific insulation resistance colored solid particles are dispersed in together with a polarity regulator and then the same amount of water is emulsified in order to reduce the flammability of the carrier liquid. In this way, however, one does not get a satisfactory, liquid one Developer, since the water it contains is applied to an electrostatic

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Such a latent image has a destructive effect · In addition, this is a developer also disadvantageous insofar as it is insufficiently stable, especially in dispersion "

The invention aims to eliminate these disadvantages of Emulsion type developers and accomplishes this through creation a new type of liquid developer for electrostatic Latent images, which is characterized by the fact that it consists of a Carrier liquid with a specific insulation resistance of more than ICr Ohm «cm and a dielectric constant of less than 3 and one imprisoned therein in the carrier liquid insoluble colored solution consists of polar solvent and color substance solution

By combining a solution of colored solid particles and polar solvent are achieved in terms of both emulsification of the carrier liquid and fixation ability of the colored particles on the electrostatic latent image was a remarkable improvement. The developer of the present invention consists thus from a dispersion which is obtained by emulsifying such a colored solution in such a carrier liquid in a volume ratio less than 1 wins

Such a dispersion is capable of producing on a carrier, Preserve electrostatic latent image for up to JO seconds. Since, in the development of electrostatic latent images, the development time and image density are in an exponential functional relationship stand and the effective development can be carried out completely within the first 10 seconds, the is suitable dispersion according to the invention because of its latent image retention capacity as a liquid developer.

Most of the above-mentioned requirements with regard to insulation resistance and dielectric constant

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Carrier liquids used for liquid developers are sufficient. These include, for example, aromatic hydrocarbons, like toluene and benzene «petroleum hydrocarbons like ligroin, Naphtha, isoparaffin and paraffin, as well as chlorinated and chlorofluorocarbons such as carbon tetrachloride and the like.

The solvent for the colored solids never shared solubility with the carrier liquid, but in contrast to it has a low specific insulation resistance and high dielectric constant.Suitable liquids of this type are water, ethylene glycol ether, e.g. Methyl and ethyl-y ethylene glycol ethers, lower aliphatic ethers Alcohols, e.g. methanol and ethanol, aliphatic ketones, e.g. acetone and methyl ethyl ketone, and lower aliphatic amines, z. B. Propylamine, Dl & thylamine and Triethylamine «

All examples of colored solid particles are selenium the numerous Diazo compounds including carbon green, carbon blue B, Carbon crimson BS (each made by the British ICI Co.), aniline black, fuel black (the latter both made by the Orient Pigment Co. Ltd.) and Alkaiibl ^ i.

Evidently, a liquid developer for an electrostatic latent image must leave this completely undamaged on the carrier for the required development time (about 10 seconds), and the particles dispersed in its carrier liquid must retain a certain polarity.

With regard to the preservation of the latent image, the developer according to the invention is sufficient since, as mentioned above, it guaranteed during the required development period.

In addition, the polarity of the dispersed Particle taking into account the mutual relationships

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between the colored solid particles "their solvent and the carrier liquid the most favorable condition to be found""the · _m ·

There are no restrictions with regard to the production of the developer according to the invention * In general, however, it is advantageous to let the colored solution drip into the constantly agitated embossing liquid, whereby its dispersion can be improved by adding an emulsion-promoting, surface-active substance. For this purpose, for example, a quarts> as0] oniu! Gsals * is suitable, as can be achieved by treating one with a carboxyl radical and a long-term alkali; occupied polymer «with W Tr! Ethanolamine, Triethanolamin, Trimetfcf lasitft © der frläthy X- amine, as well as a {! «mixture of oleic acid and Srigtlianol * amine, from naphthenic acid and tr! ethanolamine., from stearic acid and tributylamine or from stearic acid and tripropylamine and like "

Such copolgmPot with CarfcoagrX * · unÄ 3, -sisgket-tigeia alkyl radical are """"

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In contrast to the usual, liquid developers from solids : Liquid ι liquid type is the developer according to the invention in terms of the relationship between colored Substance and carrier liquid of liquid: liquid-type and therefore has a comparatively very low, volume-tris ches ratio of disperse phase to dispersion medium on.

This fact must be viewed as an important feature of the invention as it favors a stable developer state

In addition, the practical adhesion of sufficient polarity possessing, fine drops of the colored solution on the electrostatic Latent image both improved image fixation and greater penetration of the dye solvent into the Bearer surrender.

The stabilizing effect of the solvent of the colored Solution is pronounced when using alcohols / Besonaers and is by far sufficient when using water

In this respect, the invention differs significantly from the known developer in further respects according to. Japanese Patent 266 404, in which water is only used to produce emulsions to be dispersed in the liquid developer

In the following, the invention is based on six preferred ones Embodiments explained in more detail without being limited to them

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Example A.

1 g of surface-active substance in the form of an oleic acid-triethanol mixture (molar ratio 1: 3) is mixed well into 10 ml of methanol in which 0.1 g of fuel black is dissolved as a colored substance, and 10 parts of this mixture are converted into 50 parts of petroleum hydrocarbon in the form the commodity ^M Isopar H "from Esso Standard Oll Co. elndlsperglert.

Example B.

™ In 10 ml of ethylene glycol monoethyl ether, in which as a coloring Substance 0.1 g of Alkali Blue (product of Orient Pigment Co., Ltd) is dissolved, 1.5 g of surfactant is in the form of a lauryl methacrylate-acrylic acid mixture (molar ratio 9: 1) and 20 g of toluene are mixed in thoroughly. The mixture thus obtained is into a petroleum hydrocarbon in the form of the commercial commodity "naphtha No 6 "from Shell Oil Co. dispersed in a proportion of 1:50 ·

Example C

• In 10 ml of distilled water, in which as a coloring substance 0.1 g carbon crimson BS (product of ICI Co ·) are dissolved, 1.5 g surface-active substance in the form of a TrI propy lamln-S tear well mixed into the acidic mixture (molar ratio 3: 1) 20:50 dispersed.

Example D ι

In 10 ml of methyl ethyl ketone, in which 0.1 g as the coloring substance Aniline Black (product of Orient Pigment Co., Ltd) is dissolved, surfactant, namely water with a

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10 pounds of solution of thanolamine and naphthenic acid, well mixed in The mixture obtained in this way is poured into Xsopar H (example A) in the proportion of 1Oi50 completely dispersed "

Example E.

In a homomixer, 1 @@ tf £, oht part of a lauryl methaoryl & t-aorylatoopolymer (molar ratio 7OsJO), 0, QX parts by weight of carbolan army Ln BS and 20 parts of distilled water JO minutes are gösais @ Ii & _a Die -so obtained In Isopar H {example. A) eat
creating a stabilizing

Example F

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2 \ iaer amount of suitable Kimst! Iars © s to ü @ n_ ψοτ · Developing one can also achieve an even better image on copy paper «

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Claims (3)

Kabushiki Kaisha Ricoh
Tokyo, Japan Claims I) J Liquid developer for electrostatic latent images, characterized in that it consists of a carrier liquid with a specific insulation resistance of more is as ICR Ohm.cm and a dielectric constant of GR w niger than 3 and an incorporated by dispersion is insoluble in the carrier liquid, colored solution of polar solvent and coloring matter substance solution. 2) Developer according to claim 1, characterized in that the polar solvent consists of water, lower aliphatic Alcohols, lower aliphatic ketones, ethylene glycol ethers or aliphatic amines. 3) Developer according to claim 1 or 2, characterized in that the colored solution is a surface-active substance in the form of a mixture of oleic acid and triethanolamine, a mixture of naphthenic acid and triethanolamine, one Mixture of stearic acid and tributylamine, a mixture from stearic acid and tripropylamine or a quaternary ammonium salt contains a copolymer in the form of lauryl methacrylate acrylic acid, Octyl methacrylate-acrylic acid-ethyl methacrylate, Hexyl methacrylate-acrylic acid-stearyl acrylate, vinylbenzoic acid-butyl acrylate, Tridecyl vinyl ether acrylic acid, hexyl vinyl ether inconic acid, vinyl laurate acrylic acid, vinyl octylate vinyl benzoic acid, Vinyl palmitate-styrene-maleic acid, dodecyl acrylate-vinyltoluene-methacrylic acid, stearyl vinyl ether-vinyl benzoic acid, Vinylhexylate-methacrylic acid, octylvinylether-styrene-malelic acid, Octyl acrylate-styrene-phthalic acid or n-heptacyl methacrylate-styrene-tartaric acid. 0 0 9 8 2 1/16 6 7