DE1094700B - Process for continuously cleaning endless printing blankets - Google Patents

Description

GERMAN

The present invention relates to an embodiment of the method for continuously cleaning endless Printing blankets according to claim 10 of patent 860 044, according to which it has already been proposed consisting of elastic, cold-drawn threads of a linear, synthetic high polymer to provide a clean textile top layer of a printing blanket with a blocking agent, which is at Later drying as a thin film is deposited on the fabric, whereupon the blanket is dried and in this state the print zone is fed to after taking up excess ink in a Washing device treated by water-moistened brushes with water and pressure by roller press Water and paint to be freed.

The use of a barrier means in such printing blankets made of synthetic threads is therefore became necessary because, in contrast to the earlier printing blankets, in which the excess of Paint just hit an impermeable surface, now the excess paint is absorbed and into the capillary spaces between the fibers of the yarn is retained. It becomes essential larger amounts of ink that penetrate through the goods during printing or over the weaving edge the samples going beyond the goods are transferred directly to the blanket, picked up and carried away. These large amounts of color can be practically perfect when using common colors can be removed when the blanket is treated with warm water and then between press rollers leads through.

Recently, however, pigment inks are increasingly being used which, in contrast to the dyes used previously are thickened with resins that swell in water. These are dispersions with a phase of thermosetting plastic and water as the other phase, both being water-in-oil emulsions and oil-in-water emulsions can be used. The dyes are usually in suspended in the dispersion, depending on the type of emulsion, the resin solution either the outer or inner Phase forms.

Both types of pigment inks behave the same when used as a thin film on textiles or on the Harden the blanket as it passes through the drying cylinder. By water treatment with the following After passing through the drying cylinder, pressing can be done with such pigment color dispersions dirty blanket can no longer be cleaned.

It has therefore already been proposed according to patent 860 044 (claim 10), on the surface of the printing blanket a thin film as a barrier method for uninterrupted
Cleaning endless printing blankets

Addendum to patent 860 044

Applicant:

W. R. Grace & Co.,

Cambridge, Mass. (V. St. A.)

Representative:

Dipl.-Chem. Dr. rer. nat. J.-D. Mr. v. Uexkull,
Patent attorney, Hamburg-Hochkamp, Königgrätzstr. 8th

Claimed priority:
V. St. v. America 6 February 1952

William C. Ross, Winchester, Mass.,

and Alec W. Niconchuk, Peabody, Mass. (V. St. A.),

have been named as inventors

to be applied before the surface in the print zone comes into contact with the pigment inks. if then, after such a pretreatment, the ink-smeared part of the printing blanket in the washing zone is treated with water, brushed and pressed, the pigment colors are also removed from the surface layer removed. According to the main patent, means have been proposed as blocking means, which according to the Squeezing off liquid and / or drying left a thin film on the tissue, e.g. B. Detergents, such as soap (1% sodium oleate in water) or pine oil emulsion, various combinations of the Main components of soap detergents, pine oil substitutes and suspensions of bentonite and pyrophosphoric acid Sodium.

As long as when working with emulsion paints the hydrophilic detergents remove the individual fibers of the Wrap the yarn completely before a varnish-like resin deposit with the surface of the printing blanket comes into contact, the emulsion inks can also be removed from the blanket with satisfaction.

Recently, however, the proportion of resin in the pigment color pastes has been increased in order to prevent the slight staining avoid, which until then had been a characteristic property of pigment colors. the

009 678/455

Resin concentration in the so-called "highly blended" color pastes is so high that one can use barrier layers from soaps or the cleaning agents according to patent 860 044 no longer the entire amount of paint can remove.

Investigations on highly blended pigment inks left on the blanket showed that that the color, especially at the edges of the printing blanket, is almost continuous and lacquer-like Coating does not form a coherent film, while the low-cut colors and can be easily emulsified in soapy water and brushed off the blanket. The highly blended colors, on the other hand, are difficult to emulsify. * 5

These disadvantages cannot be remedied by a longer washing process, as the hard film even then does not solve. In addition, the approximately 40 m long printing blankets usually run along a speed of about 50 to 200 m / min, ao and there are only about always 2 to 3 m of blanket in the washing zone. The printing blanket must therefore usually be complete in the short time of 2 to 3 seconds cleaned if you don't want to slow down the whole printing process.

It has now been found that when using the highly diluted pigment preparations, the formation an impermeable resin film on the fiber can be prevented if the resin film in a can maintain a pulpy gelatinous state, which can then be easily removed by brushing and washing liquid can be removed in a very short time.

According to the invention, the use of a substance as a barrier agent is proposed, which is the pigment film soft and gelatinous, which furthermore does not attack the surface or the printing blanket itself Drying of the blanket does not evaporate and that together with the ink preparation by means of brushes and Washing liquid can be removed quickly and easily; a solution of liquid petroleum hydrocarbons known as rubber extenders in a volatile hydrocarbon found of poor rubber solvency.

Surprisingly, when used in very small amounts, this auxiliary material prevents hardening of the pigment film, regardless of how long it has been heated to cure the resin was. It was found that by applying this auxiliary substance to the surface of the printing blanket, Before it comes into contact with the pigment inks, the surface of the blanket itself changes after the Washing with soap is still soft and slippery to the touch, while normal printing blankets are rough and grippy touches. When the rubber extender, i. H. the barrier layer that is absorbed by the fiber comes from the Color is no longer in contact with the real fiber surface. If there is a bigger one on the fiber The amount of extender then remains than is necessary to form an approximately monomolecular layer This proportion of the extender has a gelatinizing effect on the subsequently applied paint film at least to the extent that the immediately adjacent resin portions are gelatinized.

Furthermore, according to the invention, a further extender is used after printing onto the printing blanket applied, whereby the resin layer softened from below - i.e. from the fiber - also from the Surface is softened or swollen. According to the invention, the printing blanket contains before application of the locking means already described in patent 860044 Detergent on the fibers.

Printing blankets treated in this way are easy to clean, no matter how high the inks are with resins are blended. However, in order to accelerate the cleaning process and to carry it out in the shortest possible time, it is proposed according to the invention to add an emulsifying agent to the rubber extender. This not only keeps the dye or pigment coating soft, so that it is washed off flaky can be, but it is also dispersed so that the printing blanket in a normal Blanket washer can be washed out immediately and completely at normal printing speed. Investigations with various oil-soluble emulsifiers on various pigment colors showed that the Agents had different degrees of effectiveness, but generally 1 to 2 percent by weight of emulsifier was sufficient, based on the resin content of the pigment color in order to achieve rapid dispersion of the color film.

The amount of emulsifier required is directly proportional to the amount of paint to be removed. She changes the pattern depends on the goods and the color.

The following \ ^r erhältniszahlen are to be regarded as average values and have the respective requirements can be varied accordingly by the printer. For example, if the amount of paint to be removed is very small, the amount of extender must be increased, while if the amount of paint is very large, the amount of emulsifier must be increased, but in no case should more than 1 part of emulsifier be used for 2 parts of extender. The solution can be heavily diluted with volatile hydrocarbons if the proportion of non-volatile substances that must be applied to the blanket is very small. The upper limit should not be more than 2.2 kg of non-volatile substances per 1000 m ^{2 of} blanket.

The usual color pastes have an emulsifier of 8 to 15 percent by weight, based on the rubber extender in the cleaning solution, has a strong enough effect on the resin film when the inked blanket is wetted with the solution after passing through the pressure zone.

When several dyes are applied to the blanket at the same time, some of which are color pastes Oil-in-water emulsions, while others are water-in-oil emulsions, will be advantageous not only used oil-soluble emulsifiers, which dissolve in the rubber extender, but also those that are also soluble in water. The oil solubility of the emulsifier is to dissolve the emulsifier necessary in the extender, oil- and water-soluble Emulsifiers, on the other hand, are much more advantageous and increase the efficiency of the cleaning solution.

The rubber plug-in agents are made from certain residues from petroleum refining. the The nature and method of manufacture of these products depend to some extent on the nature of the Crude product and the refining method used. They react with sulfur and can vulcanized together with rubber. These compounds are described in U.S. Patent 2,180,367 and in a publication in Rubber Age, Vol. 69, pp. 559 ff. (1951). In the case of the applied Processes are preferably used rubber extenders whose viscosity is above 7000 Say

bolt seconds is 38 ° C. Extenders with lower viscosity are less suitable because they are in the Penetrate the blanket surface and be absorbed by it. The rubber extenders themselves are exceptionally little volatile, so that sufficient on the printing blanket threads after heat drying Remaining amounts of extender that act on the pigment colors.

With an extremely small amount of extender it is already possible to improve the nature of the film change. The extender is used in dilute solution, with a volatile solvent (low-boiling) gasoline distillate, which has a low dissolving power for rubber, is used will.

The method according to the invention is to be described in more detail below with reference to exemplary embodiments will.

As a locking agent, which occurs after the press drying and before the ao Drying is applied and which through the latter as a thin enveloping layer on the fibers is precipitated, the above-mentioned residues from oil refining are used. These are mostly dark colored, mostly high or medium boiling products.

These rubber extenders are dissolved in white spirit, the dissolving power of this white spirit is very large in and of itself but small with respect to rubber; this is because of the under Use of rubber-made printing blankets is necessary in view of any damage. About 1600 parts of white spirit are used per 100 parts of rubber extenders.

As already mentioned at the beginning, it has proven to be useful to add the rubber extender to add an emulsifier so that later cleaning during the washing process is facilitated. This addition is not absolutely necessary and can be omitted for color pastes with a lower resin content However, if the resin content is higher, the addition of emulsifiers is necessary for quick cleaning. as Emulsifiers are polyoxyethylene lauryl alcohol, fatty acid esters of a polyether alcohol and lauric acid diesters of polyethylene glycol has proven particularly effective.

When using an emulsifier - d. H. with a high resin content - the barrier agent solution can be as follows Composition have:

Parts by weight ^ ⁰

Rubber extender 90

PmiiiffQfni- in

JLjJLIAUIgCtHJl ·· IW

Solvent (white spirit) 1600

As a cleaning solution to be applied to the soiled printing blanket, the following composition Find use, whereby the application should take place as close as possible to the pressure zone:

Parts by weight

Rubber extender 90

Emulsifier 10

Solvent "'(white spirit) ".'. '.'. '.'. '.'. '. 1600

The amount of cleaning solution required to clean the blanket depends on the amount of ink to be removed. Usually 4 to 141 solutions per 1000 m ^{2 of} soiled blanket are sufficient.

The barrier solution is ■ - · as already mentioned - then applied to the printing blanket when / υυ

it leaves the press dryer of the washing apparatus, ie is freed from the excess detergent solution, before it goes over the heated drying cylinder. In the heat dryer, the remaining water and the solvent are largely driven off, so that essentially dry printing blanket is fed into the printing zone. A distribution of 4.5 l of blocking agent solution on 1000 m ^{2 of} printing blanket can be sufficient to prevent any adhesion of the ink on the printing blanket, whereby the care and experience of the printer are crucial. Experienced printers can regulate their washer with certain patterns so carefully that the printing blanket always carries sufficient amounts of blocking agent with it to remain clean even after 1000 passes without further blocking agent having to be applied to the printing blanket after washing. Since there is not always such a degree of care or experience, according to the invention, when practicing the method, a dilute barrier agent solution is always applied to the printing blanket after washing, so that an average printer is able to keep his printing blanket clean.

When using pigment inks, printing blankets are made of materials in use that are opposite resistant to oil and solvents. The latter influence the hardness and only to a very small extent Wear resistance of the cloths, so that their service life is not reduced.

A printing machine with an applicator for blocking agents and cleaning agents is shown shown. Somewhere along the way of the printing blanket, preferably behind the printing zone, if possible, the dirty blanket is passed under an application roller 36 through which immediately a thin film of extender is applied to the paint-containing surface. The solution is from the container 37 brought up via a pipe 38 with control valve 39 to a V-shaped box lock 41, which the Length of the application roller 36 has. After adjusting the valve 39, the solution drips from the Lock on roller 36.

The printing blanket 23 ′ then runs into the washing zone. The roller 36 is advantageously arranged as far away as possible from the washing zone than ever The longer the solution remains in contact with the ink on the surface of the blanket, the softer and the more gelatinous the color becomes and the easier it can be removed by washing. In the Washing zone, the printing blanket runs around the main washing cylinder27 'and meets a number of

- _t 11 - 1 * 1 *

different rotating brushes, some of which move in the opposite direction to the printing blanket. They are equipped with water nozzles 48 and 50 which are directed at the bristles of the brushes so that the bristles can be washed free of color accumulation from time to time. The brushes 51 and 53 rotate in opposite directions to each other. Your bristles are ^{immersed in} soap dishes 52 and 54 so that the blanket ^{surface is} brushed off with a soap solution at this point. The brush 55 rotates in the opposite direction at a much greater speed than the printing blanket. Following the brush 55, a soap solution is applied to the printing blanket through a drip device 32 'fed by the soap container 33'. The excess soap solution that flows over the blanket surface is brushed back by the brush 55 and maintains the soap solution level in the bowls 52 and 54.

A rubber-coated squeezing roller is preferably used as roller 34 ', which if possible is provided with an air cushion, so that the pressure on the printing blanket is controlled quickly and accurately can be. Another application roller 42 is arranged immediately behind the nip roller. This is used to apply the barrier agent and is mixed with a dilute rubber extender solution fed, which from the container 43 via a control valve 44 and a V-shaped lock box 45 flows, which has the length of the cushion roll. The blanket is then placed over a series of Drying cylinders 35 'out, which are preferably located in a housing 57, which by a fan 56 is supplied with fresh air. The dried blanket 23 'then comes into the printing zone, is guided under the textile 25 'and under the inking rollers 26', 26 'and runs around the impression cylinder 24 'of the printing press around. If 4 to 14 1 cleaning liquid by means of the roller 36 and about 4 1 barrier agent solution can be applied to the printing blanket by means of roller 42 and when the nip roller pressure is set so that the blanket feels dry when it leaves the press roller, the machine can work with pigment inks for a long time and thoroughly clean the printing blanket.

The ones used to blend the pigments and to adhere them to the fabrics Resins are various. There are urea-formaldehyde resins, melamine resins and modified ones Alkyd resins used. The color pigments are not always known according to their composition, and the The type of resin is rarely known to the textile printer and changes frequently.

From time to time completely new types of resin appear in the color pastes. Marriage an expensive blanket in the case of an unknown color composition is risked, it is suggested to change the color in the following way Way to check their washability:

A small evaporation tray is smeared with color paste and added a few drops of extender solution to the goo. Then the Evaporation dish placed in an oven heated to such an extent that the volatile solvent is driven off and the resin is hardened. If the resin does not set in the presence of the extender solution, but remains gelatinous, then it is fairly certain that the color will be different from that in the manner described Blanket can be washed off.

Tests with a large number of typical pigment pastes commonly used in the textile industry have shown that all colors remained soft and could be easily removed. It was continued with investigations found on a factory scale that using high resin ink emulsions, the blankets can be reliably washed and cleaned and have a long lifespan without that ink sets in or on the printing blanket when treated in the manner according to the invention will.

Claims (3)

Patent claims: 1. Formation of the method for the uninterrupted cleaning of endless printing blankets according to Claim 10 of patent 860 044, which is a textile top layer made of elastic, cold-drawn threads of a synthetic, linear high polymer, with in uninterrupted operation a barrier agent is applied to the washed textile surface, which turns out to be thinner The film is deposited on the fabric, whereupon the blanket is dried and in this state Print point is fed to after contamination by excess color paste in a washing device treated by water-moistened washing brushes and detergents and to be freed of water and paint by roller pressure, characterized in that as Apply a blocking agent to the washed, squeezed-out printing blanket that still contains detergent residues Solution of liquid hydrocarbons known per se as rubber extenders Petroleum refining residues in a volatile hydrocarbon of poor rubber solvency is applied and immediately after the printing process one of the extender solutions continues to be applied to the dirty printing blanket similar liquid is sprayed on as a swelling agent for the paint residues. 2. The method according to claim 1, characterized in that a rubber-extender solution as the blocking agent is used which contains an oil-soluble, nonionic emulsifying agent. 3. The method according to claim 1 and 2, characterized in that a rubber extender is used which has a viscosity of at least 7000 Savbolt seconds at 38 ° C. Considered publications:
French Patent No. 814,349;
U.S. Patent No. 2,438,038;
"Metalloberfläche" magazine, issue B, 1951, issue 4, p. 57/58. 1 sheet of drawings © 009 678 / 4SS 12.60