DE2054803A1 - Liquid toner mixture - Google Patents

Description

205A803

LAWYER?

DR. JUR. '.->' --Ci ? EM. WALTER AT

ALFRED r! -. \ Vi-IHiHl

DR. JDR. Tue, 1. -C ^ iA H-J. WOLFF R. foöV. $ 70

DR. JUU. HA., 3 CiIR. IiEIL

623 FRANKFURT AM MAIN-HÖCHST

ADaONSlKASSJ-M

Our no. 16 624

GAP Corporation New York, N.Y., V.St.A.

Liquid toner mix

The present invention relates to a liquid toner composition for use in electrostatic printing processes.

A large number of liquid toner mixtures are already known for electrostatic printing processes, but there are numerous of them not fully satisfactory as they do not remain sufficiently in suspension or result in copies that are not uniform are pulled out, bleeding or causing similar defects.

It is known that various liquid developers or toners are electrophotographic on photoconductive surfaces Create images in different colors. For example, if the photoconductive surface contains zinc oxide, a negative one

carries an electrostatic charge, the developer particles suspended in a liquid carrier must be positive Assume polarity with respect to the latent electrostatic image formed on the zinc oxide surface.

109821/1801

In order to overcome the disadvantages and shortcomings still occurring so far, different types of positive working electrostatic toners. Such formulations require the use of a charge control By means of, for example, a heavy metal salt. Typical salts of this type are copper, cobalt and zinc salts. Numerous corresponding formulations are slow drying and they produce dirty white areas.

It has now been found that excellent electrostatic developers overcome the disadvantages of the previously used Materials are free, are provided by a system which contains an electrically insulating carrier liquid Pigment such as carbon black and a copolymer of maleic anhydride and a higher alkyl vinyl ether. The copolymer combines the properties that such a formulation usually possesses due to the dispersant, the fixing agent and the charge controlling agent are bestowed. It has also been found that a copolymer of maleic ^ Acid anhydride and a higher alkyl vinyl ether in which the alkyl group has about 16 to 22 carbon atoms, and which was prepared by adding maleic anhydride to the higher alkyl vinyl ether, particularly advantageous is. With the system according to the invention, a self-fixing, quick-drying image as well as a very dense one is obtained Image formed with clean white surrounding area.

The present invention thus provides a liquid, positive-working electrostatic toner mixture which an electrically insulating carrier liquid with a pigment, for example carbon black, and a mixed polymer of maleic anhydride and a higher alkyl vinyl ether of about Contains 16 to 22 carbon atoms in the alkyl group.

109821/1801

The preferred interpolymer is a interpolymer of maleic anhydride and n-octadecyl vinyl ether.

It has also been found that mixed polymers of maleic anhydride and higher alkyl vinyl ethers produced by adding maleic anhydride to vinyl ether due to their better solubility in hydrocarbons are particularly useful. These copolymers can be used in be prepared conventionally, for example by copolymerization of maleic anhydride and a higher alkyl vinyl ethers in solution using a free radical initiator. After the end of the polymerization the precipitated copolymer can be isolated in any suitable manner, for example by filtration, then it is washed with liquid solvent and dried in vacuo.

The amount of solvent is not critical; the solvent should be a suitable medium for both monomers. Solvents such as benzene, toluene, OxyIoI, acetone, cyclohexane, saturated petroleum hydrocarbons, methyl ethyl ketone, and methylene chloride and the like, and mixtures of such solvents can be used. 4-) An isoparaffinic petroleum hydrocarbon fraction with an average molecular weight of 146 and a boiling range of 160 to 165.degree. C. proved to be particularly suitable. In general, the solvent should have a boiling range between about 150 and about 250 ° C.

Suitable initiators which form free radicals are: azo-bis-isobutyronitrile, benzoyl peroxide, lauroyl peroxide, Caprylyl peroxide, acetyl peroxide, butyryl peroxide, acetylbenzoyl peroxide, Succinyl peroxide, di-tert-butyl peroxide,

+) Humble's "Isopar G",

109821/1801

Dimethyl azo isobutyrate and the like. Even mixtures of these Catalysts can be used in the production / copolymers will. In addition, radiation polymerization can be used, with energy-related radiation sources such as UV radiation, X-rays, the like. can be used.

The polymerization can take place at temperatures between 0 and about 150.degree.

Examples of suitable monomers are alkyl vinyl ethers called:

Hexadecyl vinyl ether, octadecyl vinyl ether, eicosyl vinyl ether, Docosyl vinyl ether and the like and mixtures thereof.

The liquid toner mixture according to the invention contains one of the electrically insulating liquids customary in such developers as a carrier. Such electrically insulating carrier liquids are generally hydrocarbon solvents with the required dielectric constant of, for example, less than 3 and a volume resistivity of, for example, more than 10 ohm cm. The solvent can contain various hydrocarbons, such as Isopar G with a boiling range of 160 to 175 ° C, or SiLvesso 100 with a boiling range of about 160 to ⁰

The coloring agent or pigment used is those conventionally used in electrostatic toners Pigments. The pigment can, for example, consist of carbon black, acetylene black or the like. The pigment will, in the carrier liquid suspended, used as a toner in the amount that is required so that it is attracted to the negative electrostatic Image only image-wise deposited due to the positive influence of the mixed polymer pigment and thus the desired one positive copy is generated. Generally the pigment lies

109871/1 «01

in relation to the mixed polymer in amounts between about 2.5: 1 and 1:40. When using the composition according to the invention, which is a copolymer of maleic anhydride and an alkyl vinyl ether with alkyl groups of about 16 to 22 Contains carbon atoms is, as already mentioned, the addition of modifiers such as metal soaps or salts in the generally superfluous.

example 1

The following components are mixed together:

200 ml "Isopar G"

5 g carbon black (Witco Continex EPP)

50 g "Gantrez AN 8194" (mixed polymer of n-octadecyl vinyl ether and maleic anhydride, 40 ^ solution in toluene).

The mixture is at 23> 9 ° C in a Blackstone 500 watt Ultras chall dispersion unit irradiated for 20 minutes to disperse the carbon black in the resin solution. 7 ml of the resulting Concentrate are diluted with Isopar G to 1 liter, giving a toner dispersion that is common in Office copy machines can be used. The optical density of the dispersion was about 7

A sheet coated with zinc oxide was exposed to light to form a negatively charged image and this was in the dispersion according to Example 1 is immersed. A positive reproduction of the original was obtained. The copy was of high quality, i.e., there was no colored background, the image was with a jet black print density filled in, it was also sharp and smear-proof.

10 9821 /

The dispersion showed no tendency to settle or agglomerate.

Example 2

The procedure of Example 1 was repeated using a carbon black / resin ratio of 2.5: 1. There were equally good ones Preserved reproductions.

Example 3

The procedure of Example 1 was repeated using a RuE / resin ratio of 1: 1. As in example 1 it was a good, clear positive reproduction of the original.

Example 4

The procedure of Example 1 was repeated again using a carbon black / resin ratio of 1: 2. Here too a gite reproduction was achieved.

Example 5

Following the procedure of Example 1, a dispersion with a carbon black / resin ratio of 1: 4 was prepared. Also with This dispersion produced high quality positive reproductions of the original.

Example 6

The procedure of Example 1 was repeated using a carbon black / resin ratio of 1: 8. With this dispersion positive reproductions of an original of good quality were obtained.

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205A803

- 7 ·.

Example 7

Following the procedure of Example 1, a dispersion was obtained made with a carbon black / resin ratio of 1:20. With this, too, copies of good quality were obtained.

Example 8

The procedure of Example 1 was repeated using a carbon black / resin ratio of 1:40. As in example 1 a positive reproduction of the original of good quality was obtained.

Example 9

Examples 1 to 7 were repeated, but instead of the carbon black Continex EPP Columbian Carbon Lampblack No. 8 was used. This, too, resulted in high quality positive reproductions of the original.

Example 10

Examples 1 to 7 were also repeated using aer Carbon Black Continex EPP by Columbian Carbon Channel Black No. 999 was replaced. Here, too, were positive in all cases Good quality reproductions received.

Example 11

Example 1 was repeated, but the pigment was replaced by Milori Blue (CI. Pigment Blue 27). With the corresponding dispersion, a blue-colored positive reproduction of the original was obtained.

109871/1801

Example 12

Example 11 was repeated using alkali blue (CI. Acid Blue 119) instead of Milori blue. With the dispersion thus obtained became a blue positive image good quality received.

Example 13

Example 11 was repeated using pigment green B (CI. Pigment Green 8) instead of Kilori blue, A green positive image of good quality was obtained with the appropriate dispersion.

Example 14

Example 11 was repeated using permanent carmine PB (CI. Pigment Red 5) instead of LIiIo ri blue. A carmin-red positive image of good quality was obtained with the dispersion thus obtained.

Example 15

Example 11 was repeated using anthragen red-violet ΠΙΙ (C.I. Vat Violet 2) as a pigment instead of Milori blue. A red positive image of good image quality was obtained with the dispersion thus obtained.

Example 16 *

Example 15 was repeated using Hansa Yellow GR (CI. Pigment Yellow 2) instead of Anthragen Hot Violet. The dispersion obtained in this way produced a yellow positive image received with good image quality.

109821/1801

The preceding examples demonstrate the ability of the inventive toner to be a negatively charged, latent one To convert image into a visible image, i.e. they demonstrate that the pigment particles are made up of the interpolymer Maleic anhydride and vinyl ether are given a positive charge. This gives zinc oxide layers with negatively charged layers a positive image of a positive original or a negative of a negative. If you use the invention However, toner mixtures with positively charged electrophotographic layers produce a reversal image This is explained in more detail in the following example:

Example 17

A commercially available electrophotographic printing plate, consisting essentially of an aluminum support, which is covered with a layer of a mixture of an organic photoconductor such as 2,5-bis - / _ 1T'-diethylaininophenyl (l ^f 27-l, 3, ^ - oxadiazole and one with an iristallic violet , Brilliant Green or rhodamine B sensitized insulating binder resin, was coated a PoIyindenharzes, ketone resin or phenol-formaldehyde resin, for example, is positively charged and exposed through a positive-described transparent original examples 1 After development with a toner according to -. Eat was a Reverse image of the original, namely a negatively written copy of the original is obtained.

If the image is to be particularly resistant to rubbing and smearing, a film-forming, resin-like fixing agent is expediently added to the system added.

109871-71801

This film-forming fixative not only has to be erroneously liquid Carrier be completely soluble, but it must also be able to remove the solvent by complete and rapid To give up evaporation completely, thus as an evaporation residue a coherent solid film is deposited on the solution. This film must not be sticky, it must be adhesive and be coherent so that the finished picture no longer smears. The film-forming agent may also be positive Do not interfere with charge on the particles produced by the interpolymer.

Suitable film-forming fixing agents are, for example, solid rosin esters such as diethylene glycol esters, glycerol esters of modified resins (Colophoniura), pentaerythritol ester of rosin, polymer! - siereni. Rosin, hydrogenated rosin, pentaerythritol ester dimeric resin acids, glycerol esters of polymerized rosin or hydrogenated rosin, resin-modified Phenol-formaldehyde resins, and resin-modified resins made from maleic anhydride and polyhydric alcohols. Such Products are commercially available under the trade names "Pentalyn" (manufacturer Hercules, USA) and "Amberol" (manufacturer Rohm & Haas, USA). The use of such products is illustrated by the following example:

example Ig

The following substances are mixed with one another:

200 ml "Isopar G"

5 g carbon black (Witco Continex DPF)
15 g Hercules Pentalyn H

(Pentaerythritol ester of hydrogenated rosin) 50 g "Gantrez AN 819 ¹ I" (mixed polymer of n-octadecyl vinyl ether and maleic anhydride, 40% solution in toluene)

109821/1801

This mixture is used in a Blackstone 500-watt ultrasonic dispersion unit Irradiated for 20 minutes at 21.1 ° C to disperse the carbon black in the solution. 7 ml of the resulting Toner concentrate are made up to 1 l with Isopar G, giving a toner dispersion that can be found in conventional office copier machines can be used. The optical density of the dispersion was about 7. The dispersion showed no tendency for settling or agglomeration.

A copy was made by making a zinc oxide coated Sheet was exposed to form a negatively charged image which was immersed in the above dispersion. A positive reproduction of the original was obtained. The copy was of good quality, i.e. there was none Background. The image was solid, the print density was high; the image was also sharp and extremely smudge-proof.

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Ό `` J

Claims (7)

Patent claims: Liquid toner mixture of a carrier liquid (a) and a pigment (b), characterized in that it furthermore (c) a copolymer of maleic anhydride and an alkyl vinyl ether, the alkyl group of which is about 16 to 22 Has carbon atoms. 2. Mixture according to claim 1, characterized in that it contains carbon black as pigment. 3. Mixture according to claim 2, characterized in that the ratio of pigment to mixed polymer between 2.5: 1 and 1:40 is. 4. Mixture according to claim 1, characterized in that it contains a hydrocarbon as a carrier liquid. 5. Mixture according to claim 4, characterized in that the water _{or similar} Carbon boils in the range between about 150 and 250 C, 6. Mixture according to claim 1, characterized in that it is a mixed polymer of maleic anhydride and n-octadecyl vinyl ether contains. 7. Mixture according to claim 6, characterized in that the mixed polymer by adding the maleic anhydride to the n-octadecyl vinyl ether was prepared. For GAF Corporation Lawyer 109821/1801