DE2111985A1 - Electrostatographic, liquid developer - Google Patents

Description

Bank Xerox Limited, Rank Xerox House, 338 iuston Road M Iiondon, KW »1 ₉ England

Electrostatographic liquid developer

The invention relates to an electroatatographic, liquid developer vw.ä a method » xm to develop an electroatatic latent image *

Blektrodtatographisohe, liquid developers are contained in the generally an electrical insulating dispersion medium (a carrier liquid) and a finely divided toner (generally in submicron particles) that is present in the carrier liquid is dispersed and a hgment and a resinous one Contains material.

In general, the liquid must be electric

Optimal resistance of not less than 10 ohm-cm / bteites! and suitable carrier fluids include cyclohexane , hydronaphthalene (e.g., decalin), isohydrocarbons, chlorofluorocarbons, kerosene, and various grades of commercially available petrol.

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IhISPECTBB

Pigments suitable for the toner include. Carbon black and phthalocyanine pigments. Alkyd resins and various varnishes can be used as a means of regulating the charge will.

Many methods are known to disperse the toner particles in the carrier liquid. Before dispersing the pigment particles in the carrier liquid, they must first in finely divided form in the resinous material be dispersed · Pur this purpose using different devices such as ball mills, mills with three rolls or sand mills. This results in a homogeneous mixture that contains the resinous material and the pigment and which is sometimes referred to as a paste or concentrate. Such a paste can then be diluted with the carrier liquid or dispersed in a large volume of the carrier liquid to form the liquid developer. In order to increase the dispersion stability of the diluted developer, other additives such as surface-active agents can be incorporated.

Liquid developers which have a satisfactory dispersion stability are obtained in this way by quite simple processes exhibit.

In addition to the methods described above, concentrated dispersions such as printing inks can be used. Use tar or pitch in which pigment particles are already dispersed in resinous carriers. The stable, dilute dispersions can then be divided up by simply dissolving the concentrated dispersion in carrier liquids, for example using an ultrasonic device.

However, an electrophotographic liquid developer has other important requirements in addition to

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Satisfy dispersion stability, that is, it should have high resistance ", and the toner particles should "have a certain charge polarity, either negative or positive.

It is generally difficult to regulate the latter property, charge polarity, and the number of resinous materials that are suitable to regulate the charge is quite limited. Usually Alkyd resins and linseed oil are not only used as carriers for pigments, but also as suitable charge control agents used to impart a positive charge to the dispersed particles. Attempts have however showed that the use of alkyd resin or linseed oil for the present case, especially when printing inks, Tar or pitch used is quite doubtful.

To improve the electrophoretic ^ effect of a developer, Certain additives are often used »It is desirable that they be soluble in the carrier liquid and that they have the property of regulating the charge well without affecting the specific resistance of the developer concerned is reduced too much. It is only a very limited number of connections which meet these requirements are known. A typical example are certain organometallic compounds.

The subject of the invention is an electrostatographic, liquid developer that disperses an electrically insulating carrier liquid and a finely divided toner in the carrier liquid, and a resinous material. The inventive electrostatographic, liquid developer is characterized in that it contains at least one compound selected from vinyl tri-

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äthoxysilan, ^ -Glycidoxypropyltrimethoxysilan and ß- (3, ^ EpoxycyclohexylJ-äthyltrimethoxysilan contains.

Fee status of the present invention is also a A method of developing an electrostatic latent image which consists of having the electrostatic latent image treated with the developer according to the invention.

For most applications it is desirable that the toner contain a coloring component (the term "Color," includes the colors black and white), for example a dye and / or a pigment.

Using one or more of the three organosilicon compounds mentioned above, it is possible to manufacture an electrostatographic liquid developer, under appropriate control of the ingredients and proportions, the sufficiently high electric resistance has and contains only positively charged toner particles.

Generally speaking, organosilicon compounds are sufficiently polar to dissolve in alcohol, acetone, and in some cases, water. It was determined, that compounds which are soluble in water increase the specific resistance of the developer and are therefore not suitable for the present purpose.

Surprisingly, the three above-mentioned compounds are suitable as a means of increasing the charge in electrostatographic Developers regulate their use, as they can be found in many non-polar solvents such as Cyclohexane, kerosene, decahydronaphthalene, toluene, xylene and isoparaffinic hydrocarbons are soluble.

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The remarkable importance of the present invention lies in the fact that they are developers who are quite excellent act, provides and that it is not required is to use complicated technical processes, but simply add the above-mentioned compounds to the dispersion. Since the developers of the present invention include only positively charged toners, one can use a developed one Image with improved optical density obtained using the developer of the present invention.

The present invention enables a wide variety of resinous materials to be used. Resin-shaped Material that provides developers that are unacceptable when used alone make good ones Developer together with the specified organosilicon compounds. The progress is in terms of that electrophoretic effects more pronounced than in relation to the dispersion stability.

The above mentioned compounds can also be used to increase the electrophoretic effects of dispersions made from commercially available printing ink, tar, or pitch to make developers with positive polarity to form.

As mentioned above, the present invention increases the number of raw materials used in electrostatographic Developers can be used, greatly enlarged, and in some cases is supported by the present invention simplifies the manufacture of the liquid developer containing a positively charged toner.

About the concentration of the organosilicon compounds To determine in the developer, one must consider the resistivity of the developing developer.

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· ■ O · * ■

If too small an amount is worked in, the charge-regulating amount is Effect not sufficient. The practical lower limit of the concentration is about 0.5 volume percent. The upper limit of the concentration is approximately 2 vol. #. Resistance will be above this limit of the developer in general in such a way. drigt that there is an electrostatic latent image rapidly discharges upon contact with the developer, and in some cases coagulation of the clay occurs.

The following examples illustrate the invention without it however to restrict.

example 1

5 g of black "Jet King G process H Black" offset printing ink from! Oyo Ink Manufacturing Co. were dispersed in 1000 ml of kerosene using an ultrasonic dispersion device. 10 g of vinyltriethoxysilane CH ₂ = CHSi (OC ₂ Hc) were added to the resulting dispersion. ₃ , which was purchased from Shin-etsu Chemical Ind. Under the trade name "KBE 1003 + ^11. The dispersible carbon black particles were positively charged and worked well as an electrostatographic liquid developer. When this dispersion was used for an electrostatographic latent image, the prepared "by charging a photoconductive coating layer overlying a grounded conductive substrate and exposing the charged coating to an image of light and shadow, a black toner image exhibiting satisfactory optical density was obtained.

A similar dispersion without Vinyltriäthaxysilan also containing positively charged lonerteilchen, but the electrophoretic 'effect different from batch to batch of the original ink \. Addition of the silane compound prevented such a change in properties.

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example

2 g of Channel carbon black and 50 g of alkyd resin from Japan Reichhold Chemical Ind. Under the trade name "Beckosol EL * 8002 "was purchased in a 500 ml ball mill mixed for about 2 days. The concentrated paste thus prepared was dissolved in 2000 ml of isoparaffinic solvent (Isopar H available from Esso Petroleum) disperses. In this dispersion took the main part of the Toner particles showed a positive charge, but particles with negative polarity were also present. This revealed a low density toner image when using the dispersion to develop an electrostatic latent Image with negative polarity, with haloes or rings and stripes in the image areas with high Contrast occurred.

Incorporation of 1 vol .- $ ß- (3 »4-epoxycyclohexyl) -ethyltrimethoxysilane ("KBM3O3" by Shin-etsu Chemical Ind.) In the above dispersion eliminated particles with negative Polarity. When this dispersion was used to develop a negative electrostatic latent image, so the number of haloes and stripes was decreased "and the image density was increased.

β- (3 »4-epoxycyclohexyl) -ethyltrimethoxysilane.

Example 3

A homogeneous paste was prepared by adding 200 g of S-4-Xaok made by Toyo Ink Manufacturing Co. and 10 g Channel carbon black blended on a three-roll mill. 50 g of this paste were in 2000 ml of kerosene in an ultrasonic

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Dispersionsvorriehtung dispersed. The electrophoretic properties of this dispersion varied widely depending on the manufacturing conditions, and in the above example, a very unclear, low density image was obtained when the dispersion was used to develop an electrostatic latent image of negative polarity. When 1.5 vol. # ^ "-Grlycidoxypropyltrimethoxysilane (" KBM 403 "from Shin-etsu Chemical Ind.) Was added to the dispersion, the fluctuation in effect disappeared and the toner had a stable positive charge.

CH ₂ —CHCH ₂ (CH ₂ ) ₅ Si (OCH ₃ )

^ -Glycidoxypropyltrimethoxysilane,

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Claims (2)

- 9 claims / ty electrostatographic, liquid developer, Containing an electrically insulating carrier liquid and a finely divided ion, dispersed in the carrier liquid, and a resinous material, characterized in that the developer contains at least one compound selected from vinyltriethoxysilane, ^ * - glycidoxypropyltrimethoxysilane and ß- (3 »4-epoxycyclohexyl) -äthyltrimethoxysilan, contains. 2. A developer according to claim 1, characterized gekennzeich-% net, that the carrier liquid cyclohexane, kerosene, decahydronaphthalene, toluene, xylene, or "contains a isoparaffinisehen ^{hydrocarbon.:} 3. Developer according to claim 1 or 2, characterized in that the developer contains a printing ink , pitch or tar. Use of the developer according to Claim 1 up to the development of an electrostatic latent image, characterized in that the electrostatic latent image is treated with a developer according to one of Claims 1 to 3. 109839/1612