CS254386B1 - Method of cleaning high-speed machines - Google Patents

Abstract

The method of cleaning high-speed offset machines from paint residues, pigments and other impurities uses new types of liquids containing as the main component gasoline with a boiling point of 140 to 200 °C, as well as perchloroethylene and xylenes with ethylbenzene, while the liquids contain practically no hygienically harmful benzene, or toluene and bicyclic aromatics.

Description

BACKGROUND OF THE INVENTION The present invention relates to a process for the purification of high-speed machines from paint residues, pigments and other impurities by new types of liquids containing, as the main component, gasoline boiling between 140-200 ° C, perchlorethylene and xylenes with ethylbenzene.

Offset duplicating machines are constantly improving. Recently, fast-fed types have been developed and used, capable of printing over 10,000 matt pages per hour. They are equipped with automatic rubber and roller washing equipment to ensure copy quality. After a longer cycle of work, they are then thoroughly washed, so that they are perfectly prepared for further work. Due to the substantially higher copying speed, it has been shown that methods of cleaning with conventional liquids have drawbacks that affect print quality and copy quantity. Copies are produced with poor print quality, a coating is formed on the eraser, and the eraser must be replaced frequently. Paint is precipitating from the liquid and washing of the inking rollers is not perfect.

The consumption of cleaning matrices increases by 150%.

With the method according to the invention, all difficulties can be eliminated. The process according to the invention cleans high-speed offset machines from paint residues, pigments and other impurities. At intervals automatically controlled, components, especially rubber and machine cylinders, are thoroughly washed with a liquid consisting of 50 to 80% by volume of dearomatized refined naphtha with a boiling point of 125 to 200 ° C, 10 to 25% by volume of xylenes with ethylbenzene and up to 10 up to 25% by volume of chlorinated hydrocarbon derivatives, in cold cycles of 10 to 300 minutes. The de-aromatized refined gasoline has below 2% by weight of monocoyl Cg and above.

Up to 20% by weight of ethylbenzene is present in the xylene mixture and 30 to 60% by weight of m-xylene is present in xylenes. Tetrachlorethylene is most preferred as part of the chlorinated hydrocarbon derivative component. Periodic regular washing with selected liquids against liquids formed by other components leads to an economically advantageous solution, since these components are readily available in oil refineries and the chemical industry. Their combination guarantees greater volatility than previous types of cleaning liquids and at the same time hygienic safety against solutions containing benzene or toluene. The high density of the liquid sample ensures easier removal of moisture from the machine.

In the example below, the process according to the invention is presented, the conditions being illustrative only.

Example

The high-speed offset machine from the Swiss company Robinco AB Díck 369T was first used with the offset machine labeled NIXOL. In the automatic wash cycle, the first copies are produced with poor print quality, and the offset rubber has been changed five times during 7 months of operation.

NIXOL dries slowly and, moreover, does not completely dissolve paint residues in the machine, especially on the rollers. The consumption of the cleaning matrices was 150% greater than guaranteed for a suitable liquid.

The AB Dick 369T introduced the process of the present invention and Aj was used in an automatic wash cycle. When using this liquid for several months, there was no negative effect described above and the machine was productively used without faults. The same was verified in parallel on a second machine of the same type at another workplace where the problems with the original less volatile liquid with poorer dissolution properties were the same.

None of the liquids contained benzene or toluene and there were no traces of hygienically harmful bicyclic aromatics.

None of the compared fluids containing only two of the three components of the liquid of the invention had the same positive cleaning effect.

The composition and quality of the liquid A 1 is shown in the following table. Liquid A1 differed from the commonly used Nixol in that it contained a chlorinated hydrocarbon derivative in a concentration of 23% by volume and technical xylene.

Composition and qualities according to the invention for high-speed offset machines:

Table

Composition:% vol.

Liquid A1

Dearomatized refined naphtha

II. xylene

III. perchlorethylene

Properties:

density at 20 ° C; g / cm ^ distillation range? ° C flash point? Noc: 2 ° C

0,990

120-180

Technical xylene contained 18% by weight of ethylbenzene and 42% by weight of meta-xylene.

Claims (4)

OBJECT OF THE INVENTION 1. A method of improved cleaning of fast-fed machines from paint, pigments and other contaminants by washing with a cleaning liquid characterized in that the fast-fed machine parts are cold washed at intervals of 10 to 300 minutes with a liquid consisting of 50 to 80% by volume of dearomatized refined naphtha boiling point 125-220 ° C, preferably 130-160 ° C, from 10 to 25% by volume of a mixture of xylenes and ethylbenzene and from 10 to 25% by volume of chlorinated hydrocarbon derivatives. 2. Method of claim 1, wherein the dearomatized refined gasoline has less than 2% by weight monocyclic aromatics _Cg and higher. 3. A process according to claim 1, wherein the xylene mixture contains up to 20% by weight of ethylbenzene and the xylene is 30 to 60% by weight of m-xylene. 4. The process of claim 1 wherein the preferred chlorocarbon derivative is tetrachloro ethylene.