JPS58104795A - Composition for washing and regenerating printing screen - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] The present application is a series of applications filed on the same date as Albθrt B, Gor.
D. and Gary M. Valasek, in a series of applications entitled "Method of Cleaning and Reconditioning Printing Screens."

Background of the invention Screen printing is a well-established practical industry.

Essentially, an Ingiri screen is a fairly permanent emulsion applied locally to the dye paste or ink used in reproducing images from the screen to impart various patterns, artwork or print marks onto the screen. has been done. The emulsion surrounding the image area of the print screen is resistant to ink so that it is not removed during the printing process in which ink is applied through the screen for image reproduction. This property of the emulsion being impervious to inks and cleaning solvents makes removal of the emulsion from the printed screen extremely difficult.

Printing screens are typically made from silk, synthetic fibers or gold-tin materials and are commonly reused in commercial screen printing. This includes a cleaning step, so that ink residues from a single printing operation are removed from the screen and the screen is stored and reused. It is sometimes important that the ink removal gap not affect the areas of emulsion applied to the screen.

Rather, modern screen printing has developed complex ink or dye formulations that are often difficult to remove. The agents used to wash the ink from the screen will also act on the underlying emulsion. Screen printing thus involves a balanced chemical process in which the screen is created from semi-permanent to fully permanent emulsion artwork, and the emulsion areas resist ink attack and reproduce the ink image. . During such operations, the screen is repeatedly cleaned for storage and/or subsequent reuse. It is also important that the screen can be regenerated, in which case the ink image and/or emulsion areas are removed with different types of screen regeneration solutions or agents.

Typically, commercial screen printing shops run a large number of screens every day.
,,・ Clean also wash. , are regenerating and using screen cleaning machines or regeneration systems for this purpose. Such cleaning machines or regeneration systems typically use recycled solvents, into which synthetic or full-length screens are introduced to clean or regenerate according to production demands. Other commercial operations also include manual cleaning or reclamation using various solvents or caustics. During the cleaning or reclamation process, screen printers often come into full contact with chemicals or solvents. A number of solvents or chemicals are used for screen cleaning and regeneration. The three most commonly used agents are classified as aliphatic hydrocarbons, aromatic hydrocarbons and oxygenated solvents, and sometimes chlorinated solvents are also used. Although aliphatic hydrocarbons are commonly referred to as "mineral spirits," it is true that these aliphatic solvents are composed of a mixture of straight and/or branched chain saturated hydrocarbons.

As the molecular weight or number of carbon atoms increases, the boiling point of the solvent increases to 1 (6).The higher the boiling point, the more difficult it is for the solvent to evaporate. Aromatic hydrocarbon solvents include cyclic hydrocarbons containing benzene rings.Aromatic hydrocarbons usually have a stronger solvating power than aliphatic type bath agents, which are more flammable, and likewise Aromatic hydrocarbons have higher boiling points as their molecular weight increases.They are rather non-polar hydrocarbons, whereas oxygenated solvents are more polar compounds.Typical oxygenated solvents are hydroxyl or carbonyl groups, many of which have considerable solubility in water.Other solvents are fully or semi-chlorinated hydrocarbons, chlorinated solvents and rarely used Examples include Freon type fluorinated hydrocarbons.

Thus, today's printers are dealing with a large number of solvents used for screen cleaning and recycling. Such solvents have been used without incident when there has been negligence and little regard for the risks to the health and safety of printers or workers. Nowadays, federal and state laws require that solvents meet material safety standards. Solvents generally must avoid prolonged or repeated contact with skin, are often flammable and must be isolated from high heat or open flames, and fire departments often require outdoor storage of solvents. are doing. Also,
08HA (0ccup
ational 5aftey &ni H@alth
Administration) has placed various restrictions on the use of solvents, many of which may no longer be usable. In addition, known processes require high temperature regeneration systems to clean or regenerate printing screens, but such systems introduce unsanitary and hazardous conditions that are no longer acceptable. In researching suitable screen cleaning and regeneration solvents or agents, the DOT (
Department of Transport
on) One that does not require a red label is desirable. Also,
It would be desirable to provide cleaning and regeneration compositions that are completely or essentially biodegradable. Another highly desirable objective is to make available products for industrial cleaning and reclamation that still have marginal values1,11 and the high limits (TI,V) mean that the levitation caused by such products is The bar of material means greater breathing safety.

The above technical background is a practical overview for those skilled in the art from the standpoint of cleaning and regeneration processes in the screen printing industry.

Furthermore, in preparing this application, there are patents that are believed to be related to the main part of the present invention. The following is a list of prior patents that may be helpful in understanding the present invention, but is not intended to be exhaustive or to suggest that there may not be related patents or documents: U.S. Patents Second.
No. 780.168, No. 3.459.594, No. 3,5
No. 11,657, No. 3,615.827, No. 3.64
No. 2.537, No. 3.673.099, No. 3,679
．． No. 479, No. 3.706.691, No. 3.737.
No. 386, No. 3,764.384, No. 3,789.0
No. 07, No. 5.796.602, No. 5.928.06
No. 5, No. 3,953.352, No. 11' No. 4,024,085, No. 4,055,515 and Ya. ,. 70.20'3f. Yuwa, □,. Yo Otse,
.

It must be said that this was developed for the purpose of the present invention, and that it was obtained from a dissimilar technique. Therefore, in any event, the illustrations herein do not represent the state of the art for cleaning or remanufacturing printing screens.

It has been stated that there is a need for printing screen cleaning or reclamation compositions that are effective in a wide variety of applications. Moreover, it is highly desirable that such compositions not only be effective, but also meet environmental health and safety standards.

SUMMARY OF THE INVENTION The present invention is directed to printing screen cleaning or rejuvenation compositions that are effective to solvate or degrade inks commonly used in the printing industry.

This ink cleaning composition is suitable for cleaning a wide variety of printing inks.
It not only dissolves or decomposes, but also has a flash point or σ
] It has no flash point and has excellent biodegradability and high limit value. The health and safety of screen printers or workers in this industry is therefore greatly improved by the present invention. In addition, the present invention provides a system of cleaning and regeneration compositions that work synergistically to remove ink and can also be sensitized to effectively remove the emulsion being printed on the screen. provide. Well, in general terms, the present invention can be applied to silk, woven fabric,
Pyrrolidone (hereinafter sometimes rNM
PJ), an oxygenated solvent and a surfactant.

These essential non-aqueous systems have been found to solubilize and degrade a wide variety of polymeric and other inks widely used in the modern screen printing industry. This composition penetrates and emulsifies the ink during the removal of ink from common printing screens of various types.
It has also been found that it prevents ink from re-adhering. Additionally, the composition of MupS solvent and surfactant is not recommended for effective cleaning of the screen or for sensitizing the ink-free screen for subsequent emulsion removal if necessary. I found out that it had to be water-based.

The screen cleaning or regeneration method in this application is 14MP
, applying a non-aqueous system of oxygenated solvent and surfactant (hereinafter sometimes abbreviated as "rIMP concentrate") onto the screen surface and holding for a sufficient period of time to allow solubilization or degradation of the ink. carried out by The ink is then removed from the screen by rinsing with water. By this method, the ink is broken down into a state that is amenable to complete removal by a high pressure, low volume, water spray. A filed in the same daily
Albert B, Card and Gray M, Valas
A preferred method for applying the NMP concentrate is to spray it onto the screen ink surface, as disclosed in the co-application entitled "Method of Cleaning and Reconditioning Printing Screens" of the ek invention. By spraying with a cohesive spray of NMP concentrate, it is possible to use extremely few caps, and yet decomposition is still surprisingly achieved. It has also been found that after the ink cleaning step with the IMF concentrate, the emulsion is in a sensitized state suitable for removal from the screen with a permateate-containing emulsion remover.

This allows the screen to be completely regenerated. Thereafter, if further image ink residue or burst is required,
(as the term is used commercially) can be removed by a caustic solution containing an oxygenated solvent. According to the above sequence, the present invention also provides the entire process of cleaning and regenerating the screen.

Background of the Invention Traditionally, hot solvent and alkaline methods have been used for screen cleaning and regeneration.

The present invention obviates the need for and health risks resulting from such thermal cleaning methods. Alternatively, the invention can be practiced at ambient or room temperature conditions.

In this important respect, it is highly unexpected and contrary to the prior art that a cleaning and regenerating system can be operated at such low or ambient temperatures and be effective in removing a wide variety of ink compositions. It seems that this is not something that can be achieved easily. Furthermore, although the use of pyrrolidone derivatives, including alkylpyrrolidones, in cleaning compositions has been disclosed in prior patents, the use of pyrrolidone derivatives, including alkylpyrrolidones, in compositions or methods for removing screen printing ink compositions has been disclosed in prior patents. There is no suggestion to use either. Furthermore, even though pyrrolidones have been suggested in dissimilar art, they are generally used in aqueous systems as opposed to the essentially non-aqueous gland fluids of the present invention.

Also, for the present invention it is essential to use N-methyl-2-pyrrolidone in combination with an oxygenated solvent and a surfactant to achieve optimal effect. The screen printing industry is currently looking for non-toxic, biodegradable and very safe cleaning compositions such as those provided by the method of the present invention, which are still capable of achieving highly desirable cleaning and synergistic regeneration effects. It has not been suggested in the past that

DETAILS OF THE INVENTION As noted above, an essential component of the compositions of the present invention is N-methyl-
2-pyrrolidone, an oxygenated solvent and a surfactant.

The oxygenated solvent in a preferred composition is a combination of butyl cellosolve and cyclohexanone. These preferred oxygenated solvents are each selected from the class of glycerol, alcohol and ketone. Other types of oxygenated solvents that can be used include esters and ethers 1 and mixtures thereof. Preferably, the surfactant is selected from the group consisting of nonionic or anionic surfactants, or mixtures thereof, and specific examples of nonionic surfactants are available from PM & Hass, Inc. Octylphenoxy (polyethoxy) ethanol sold under the trademark Tam X-114 and GAF from General Aniline and Film Co.
It is an organic phosphate ester sold under the trademark AORP-710. Additionally, examples of oxygenated solvents from glycol ethers that can be used include methyl cellosolve, hexyl cellosolzo, cellosolve solvent, methyl calpitol, carpitol solvent, butyl carpitol, hexyl carpitol, and the like. Examples of other ketones include methyl ethyl ketone, methyl isobutyl ketone, methyl isoarnatone, ethyl butyl ketone, isobutyl hebutyl ketone, isophorone, diacetone alcohol, a7tone, 4-methoxy-4-methyl-2-pentanone, and the like. Ru. Examples of other ethers include butyllactone, diethylcarpitol and dibutylcarpitol, and others Examples of esters include butylactate, butyl acetate, butylcarpitol acetate, carpitol acetate, butyl cellosol deacetate , cellosolve acetate, 2-ethylhexyl acetate, amyl acetate, methyl cellosolve acetate, formate,
and others are included. Examples of alcohols include amyl alcohol, butyl alcohol, furfuror alcohol, 2-butyne-1,4-diol, and tetrahedral alcohol.
Includes fluorophores, alcohols, and others.

Therefore, according to the broad principal components of the present invention, oxygenated solvents from the above classes are used to obtain the most desirable biodegradability, least flammability and highest limits meeting or exceeding health safety standards. , are suitable for use depending on the required solvation capacity of the oxygenated solvent. However, in accordance with the preferred principal components of the invention as described above, there are specific embodiments that meet all criteria of the most preferred aspect of the invention. Generally speaking, the oxygenated solvent promotes the low viscosity solvation properties of the IMF and aids in the dispersion of the NMP to solubilize or degrade the ink composition. If necessary, the IMF also becomes water active. Therefore, the combination of NMP and oxygenated solvent has a unique water activity as well as an interaction between the organic cosolvents that synergistically solvates or decomposes the ink composition on the screen to make it suitable for water wash removal. ,
The NMP concentrate must be essentially non-aqueous in order to solvate or degrade the ink. This is because, in the lifter of the present invention, a large amount of water negates the effectiveness of IMFl, 1111 in cleaning power. However, the solvated or decomposed ink is then necessarily removable with a low volume pressurized water stream.

In addition to the surfactants listed above, other nonionic, anionic, cationic, and zwitterionic surfactants can be used; Mainly published in.

Surfactants aid in dispersing and dissolving the ink for aqueous removal. Surfactants of the anionic type are (1) saponified fatty acids or groups of soaps, or saponified petroleum salts such as sodium salts or organic sulfonates or sulfates, or (3) saponified esters, alcohols. Examples of anionic surfactants include: Included are alkaryl sulfonate or its amine salt, such as the sulfonate of dodecylbenzene or the jetanolamine salt of dodecylbenzene sulfonic acid. Most of these sulfonates contain multiple chemical moieties. The classification name given to most of these is [alkylaryl sulfonate].

Simply put, this means that the paraffinic hydrocarbon is attached to an aromatic or benzene nucleus, but the aromatic portion is sulfonated. Saponified fatty acids (06-02
Examples of 4) are the sodium or potassium salts of myristic acid, parrutic acid, stearic acid or lyluic acid, or mixtures thereof. Also, among this type of anionic surfactant, oxyl alkylated higher alkyl phenol or JJt aliphatic monohydric alcohol neutral phosphoric acid-1
vinegar? There are organophosphate esters including alkali metal salts and alkaline earth metal salts. r Aerosol
OTJ is a dioctyl alkali metal sulfosuccinate anionic surfactant manufactured by Cyanamid.

Nonionic surfactants suitable for conventional use have hydrophilic portions, usually side chains of the polyoxyalkylene type. The oil-soluble or oil-dispersible portion of the molecule is derived from either fatty acids, alcohols, amides or acenes.

By appropriate selection of the starting materials and adjustment of the length of the polyoxyalkylene chain, the surface-active portion of a nonionic detergent can be varied in a known manner. Suitable examples of nonionic surfactants include alkylphenoxypolyoxyethylene glycols such as the ethylene oxide adducts of either octyl-, nonyl- or tridecyl-phenols, and the like. These non-ionic antiaging agents are typically prepared by the reaction of alkylphenols with ethylene oxide. Trademark Triton X-100 or X-114J from Rohm & Hess
Alkyl phenyl ethers of polyethylene glycol are commercially available from Union Carbide and Carbon Co. under the trademark Tergitol J.

Other specific examples of nonionic surfactants include glyceryl monooleate, oleyl monoisozotetrapanolamide sorbitol dioleate, alkanols such as monoisozolopanolamine, jetanolamine,
Also included are alky-o-ylamides produced by reacting monositanol iamine with fatty acids such as oleic acid, pelargonic acid, lauric acid, and others. Mention may be made of cationic betaines and quaternary ammonium compounds. Specific examples of betaines include imidazoline petaines, aliphatic and carboxycyclic betaines, and betaines having heteroatoms in the hydrophobic chain, such as dodecyloxyzologyldimethylaminoacetic acid. Representative quaternary ammonium compounds that can be mentioned include dimethyl dicocoammonium chloride, cetylpyridinium acetate, methylcecylpiperizonium zoropione), N-dimethylammonium shed phosphate, etc. . It will thus be understood that other anionic, cationic, zwitterionic or nonionic surfactants can be used in accordance with the principal components of the present invention.

Although the amounts of the 1 components can vary widely, a sufficient amount of N-methoxy, 1-2-pyrrolidone, i.e., about 30 to 85% by weight, is used.
It is preferable to use Oxygenated solvents are usually about 15-3
It is contained in an amount of 5%. The size of the composition is about 1 layer f1
% to about 5% of surfactants or mixtures of surfactants. If extra fast penetration is required for better ink solubilization, add other organic solvents such as methylene chloride, trichloroethane, dimethyl sulfoxide and their Derivatives, fluorocarbons, and freons may also be supplemented. The caustic organic solvent does not change the essential properties of the ink cleaning composition of the present invention and serves to enhance the penetration, emulsification and ink degradation promoting effect of the co-solvent for subsequent removal.

To further illustrate the invention, specific working formulations and methods of cleaning and regenerating printing screens are provided below.

Example 1 75.72% N-methyl-2-pyrrolidone 18.5
2% Butyl Cello Sorzo 3.04% Cyclohexanone 2.62% Octylphenoxy (Polyethoxy) Ethanol (TR TON 114) 0.10
% Organophosphoric acid xxy-h (GAIFAORF-
710) Example 2 67.86% N-methyl-2-pyrrolidone 9.26
% Butyl cellosolve 1.52% cyclohexanone 24.00% cellosolve acetate 26.00%
Methylene chloride 1.31% Octylphenoxy (polyethoxy) ethanol (TR Engineering TOIJ X-114) 0.05%
Organic phosphoric acid: c7. f le (GAIFAORP-71
0J 5o% Example 1 in place of the specific component of Example 2
% methylene chloride and 24% 4% cellosolve acetate may be combined. Examples 1 and 2 are preferred formulations of NMP cleaning concentrates due to their biodegradability, reduced flammability, and low TL'V values.

Before detailing the cleaning and rejuvenating of printing screens using the compositions of the present invention, it is important to understand seven certain basic facts or terminology. First of all, the ink side of the printing screen is also called squeegee side, well side, or front side, but ink side is used here. The opposite side of the screen is also called the backside, downside, or printed contact side, but here we use the printed contact side. Term "ink"
A general term for a number of compositions used in practical screen printing, including soft enamels, synthetic enamels, fast-drying enamels, soft lacquers, industrial lacquers flat vinyl inks, vinyl halftone inks, fluorescent vinyl inks, gloss Vinyl ink, satin vinyl ink, Fultsuk adhesive, transparent ink, metal powder, acrylic ink,
Included are dyes or inks commonly referred to as plastisol inks, mylar inks, fiber inks, and several types of inks. As general literature regarding ink compositions, the 1978-1979 catalog of KO Graphics Co., Ltd., copyright 1978 of KO Graphics Co., Ltd., is useful. Also, (Textil@5ore@n Pr
inting) J 2nd edition, Engineering 5BNO-91138
0-39-6 (197<S year) is helpful. These documents also serve as technical background information about inks that can be cleaned with the cleaning compositions of the present invention. As previously discussed, printing screens can be made from a number of materials and have varying mesh sizes. A monofilament screen is a single strand of material, such as polyester, fiber, stainless steel, silk, plated wire, etc., woven to a specific number of meshes per unit. 230 mesh means 260 holes per square inch. Multifilament screens are made of a set of strands of similar material as described above and are woven together before being woven into a mesh. In other words, 12XX150 mesh is woven with 12 strands.6. , means a weave that is crowded and then woven with 1150 holes per square inch, in which case the pigment may enter the strands F at the intersections of the mesh, making it extremely difficult to remove. It will therefore be seen from this monofilament or multifilament discussion that the requirements for complete removal of ink, for example, vary depending on the construction of the screen. A final residue, referred to in the art as "daste" or "haze", is particularly common in multifilament screens, where the pigment becomes embedded in the strands and is extremely difficult to remove. There are many types of emulsions that initially coat the printed contact side of the screen. for example,
Direct emulsions are water-removable materials that instantly harden to non-removable materials when exposed to light of a specific wavelength. For example, the artwork can be placed in uncured emulsion soil, in which case the emulsion is reactive to water, and when you expose it to halide light, the parts of the emulsion that were not exposed because they are covered by the art are remains water-reactive. After a certain light exposure or exposure time, the art is removed and the screen is then rinsed with water to remove the unphoto-extracted areas and provide an emulsion development area through which ink flows through the screen for printing. The difficulty of emulsion removal is also related to the number of coats on the mesh, ie, the number of coats that are dried and reapplied to obtain, for example, two to about five coats of emulsion. Therefore, the difficulty of emulsion removal depends on the number of coatings, whether it is strongly sensitized, the exposure time,
It depends on a number of factors including the type of photoactivation, the chemical hardener used after emulsion development, and other factors.

Viewed from the above background, the cleaning composition of Example 1 has approximately 20%
It is a non-aqueous concentrate with a flash point of 3° PC95° C] and is designed to remove a wide variety of inks and paints from screens. Another feature of the invention is that the IMF concentrate of Example 1 treats or sensitizes many conventional emulsions for subsequent removal by low volume high pressure water washing. It is fast acting, efficient, economical as it can be used in small quantities, biodegradable and does not require the red label (DOT flammable) solvent designation. It is also safe for all screens and can be left on the screen for an extended period of time before rinsing. The composition of Example 1 may be used in recirculating solvent systems or other convenient systems. For a recirculating solvent system, the concentrate of Example 1 can be flowed over the ink side of the inclined screen and the soil may be allowed to flow for about 5 minutes. Alternatively, the ink on the screen may be sprayed evenly with a coagulating spray to prevent volatilization and then held for about 2 to 5 minutes. For example, about 30 to 100
The pressurizer is operated at Pai (typically 40 psi) to provide a condensate stream of concentrate through a nozzle approximately 6-12 # away from the screen. Mist can be avoided. In either recycled solvent or spray processes, degraded ink is easily removed by low volume water washing at high pressures, about 50-1000 psi. Low capacity means 2 to 4 gallons per minute.

Fan spray was found to be preferable to balance power and volume. A suitable fan spray nozzle may be used as described by Spray Processing Systems, Inc. (Illinois).
It is important that the screen on which the ink is solubilized or degraded is kept away from water before cleaning. N
The presence of water either in the MP concentrate or on the screen severely reduces the efficacy of the composition.

A generally preferred cleaning technique for achieving the advantages of the present invention is that disclosed and claimed in the co-pending application of Oord and Valasek. In that application, a cleaning concentrate is sprayed evenly onto the ink side of the screen for a short period of time, i.e. the cleaning system, ink composition,
Hold for a period of several minutes to several hours depending on factors including timing of treatment. During this holding time, the wash concentrate penetrates the ink, emulsifying and solubilizing it. The ink remains on the screen, but the previous ink properties are destroyed.

During the holding time, the co-solvent action of J,...,y-methyl-2-pyrrolidone and the oxygenated solvent takes place. Additionally, surfactants penetrate the ink composition for dispersion and aid in subsequent ink removal by water. The interaction of all three components enables solubilization or degradation of the ink and facilitates dispersion suitable for removal. Although the N-methyl-2-pyrrolidone provides water activity to the composition to permit removal by water, the water must be under pressure to blow the ink composition away from the screen. The components of the composition are delicately balanced so that the organic components of the ink are solubilized or decomposed by both the N-methyl-2-pyrrolidone and the oxygenated solvent. Furthermore, although the activity of N-methyl-2-pyrrolidone is degraded by water while ink solubilization and decomposition is occurring, NM
Ink that has degraded in the presence of P and co-solvent is water active and can be removed from the screen by low volume water flushing with a pressurized fan. Regarding this,
It is preferred to use a slicing fan or water jet to sweep the screen upward from the bottom so that the ink is removed without redeposition.

The composition of Example 2 above is used in the same cleaning process as the solvent-based concentrate of Example 1. However, the presence of methylene chloride improves the overall penetration of the composition, and the cellosolzoacetate improves the water droplet dissolution of the composition. Other organic solvents that can be substituted for methylene chloride include 1
．． 1.1-) Other hydrogenated solvents such as dichloroethane, dimethyl sulfoxide, its derivatives and fluorocarbons or freons. In either case,
The addition of such organic solvents to improve penetration also facilitates evaporation so that the wetting period or retention time on the screen becomes very short. For example, the composition of Example 1 is left on the screen surface for several hours, whereas the composition of Example 2 is typically used for several minutes, eg 2-5 minutes. Additionally, it should be understood that the ink solubilizing agent of Example 1 may be used in combination with the cleaning concentrate of Example 2 subsequently. For example, during the washing process the ink is solubilized with the concentrate of Example 1. In this case, the screen needs to be left for several hours or less after treatment and before the ink is washed away. In such cases, fresh decomposition concentrate of Example 2 may be applied after this hold time to activate the residue for removal by a subsequent low volume high pressure water wash. The amount of material sprayed onto the substrate is variable, but typically ranges from several ounces per square foot, such as from 2 to 4 ounces per 6 feet square of screen.

Therefore, preferably the method involves spraying the concentrate of either Example 1 or 2 onto the screen. Spraying is an economical low-volume method that allows retention time to solubilize or degrade the ink. The substrate is then exposed to a low volume high pressure water stream. □Preferably, a fan spray is used to scrape off and aid in the removal of the degraded ink composition. If the solubilized and decomposed Sufu IJ '7'' is simply immersed in water, the screen will not be cleaned at all.

Between the power of the water used and the proof': (there is a balance,
That will be understood by those skilled in the art from the description of this application.

It has been observed that a light mist associated with the screen cleaning method with face masking spray tends to adhere to other remaining areas of dissolved ink. This problem is reduced or eliminated by adding another component to the concentrate. This component is characterized as a hydrophobic additive, and in particular the water-soluble synthetic oil sold under the trademark UOON has been found to be satisfactory. Depending on the amount of water mist or splatter expected from the water wash, the surfactant unit or the components of the NMP concentrate may contain a water-dispersible oil, which is first applied to the liquid water spray or the spray. act as a water repellent for the NMP concentrate, while facilitating the removal of the low volume pressurized water stream of the ink composition previously decomposed and solubilized by the NMP concentrated koji. Such water-soluble oils are of the polyalkylene glycols commonly used in Union Carbide's UOON lubricants, although other types and mixtures of "t" II: of varying solubility in water may be used. I can do it. A preferred product from Kobunshisha □ is UOON 50-HB 5100. Specific compounds include polyalkylene glycols or oxirane polymers, OAS Registration s90
38-95-3 or ethoxylated lanolin or ethoxylated castor oil. However, it is preferred that oils of the type described herein do not remain on the screen after thorough water washing.

If the printing screen has to be completely regenerated, ie the emulsion must be completely removed after cleaning, the process is as follows. When the printing job is completed, the operator cards out or squeezes out the ink remaining on the ink side of the screen as well as the ink on the print contact side. From a very practical point of view, since ink is expensive, one must try to recover as much ink as possible. From a cleaning standpoint, excess ink requires more cleaning concentrate to remove the ink and regenerate a screen free of haze or dust residue. After the screen has been thoroughly washed, either before or after it is removed from the press, the cleaning process is started. If the process is direct regeneration, generally speaking either Example 1 or 2 concentrates can be used depending on the type of ink. Either concentrate is sprayed onto the ink side of the screen and then transferred to the regeneration area.

In a direct regeneration process, direct regeneration should begin within about 5 to 10 minutes after application of either the composition of Example 1 or 2. After spraying either concentrate, wash the image off the printed contact side of the Scriken with high-pressure water as previously described. This removes all or substantially all the ink. At the same time, the entire surface of the emulsion is wetted with water and becomes suitable for application of the periodate-containing emulsion remover. Example 1
It has also been found that there is a synergistic effect caused by the use of two non-aqueous concentrates. Even after the water wash spray, a concentrated liquid residue remains, whereby the emulsion is sensitized for rapid removal. It is believed that in this direct regeneration process the emulsion is somehow softened or made permeable to make it suitable for treatment with periodate-containing emulsion removers. A suitable example of an emulsion remover is shown in Example 6.

Example 5 94.096% water 2.880% sodium metaperiodate 3.000
% Phosphate Sodium (Anhydrous) 110#l1% Ionic Surfactant/1000 lbs Water o*yAo RP
-710 (shown above) and OAI+80FTP-
90 (sodium dodecylbenzenesulfonate) is sprayed from the cylinder side onto the screen surface and allowed to remain there for about 15 seconds to several minutes. That is generally sufficient time for the emulsion to break down. Wash the emulsion off the screen again using high pressure spray. It is important that the residual effects of the concentrates of Examples 1 or 2 after water washing, as explained above, be used immediately by applying a periodate-containing emulsion remover. a long time, e.g. 3
It has been found that it becomes difficult to remove the emulsion after 0 minutes. Therefore, the residual effect of the cleaning composition of the present invention is synergistic as long as the interaction with such periodate-containing emulsion remover removes the emulsion completely.

Finally, if a residual yeast image as described above occurs, particularly in connection with a multifilament screen, a ghost remover or image remover may be used. However, it must be noted that the occasional presence of afterimages does not necessarily impede the reuse of the screen. Some screen printers are not precise and residual smudges are not a problem as long as the screen mesh itself is not blocked.

If a ghost or haze remover is used, a typical remover is a "baseless solvent 0 caustic" solution. The reason for using something like this is 1.1llll'
, 1. It should be washable with water, i.e. it should be water soluble and it should not leave behind any residue that would later cause emulsion problems. When using this type of ghost or haze remover, due to its increased viscosity, it must be applied with a brush, roll or card rather than by spraying. A typical composition is as follows: 31.64% Cyclohexanone 19.40% Cellosolve Acetate 38.83% Sodium Hydroxide (50%) 9.61%
DOW? AI 2AI solution (70% sodium didodecylphenoxybenzenedisulfonate, 60% sodium dodecylphenoxybenzenedisulfonate) 0.01% Brilliant Milling Red Dye 0.51% GAIFAORP-710 (as indicated above) for treatment In order to fully regenerate the screen, which can be laborious, it is important to be able to process the screen, sometimes after about several hours after ink degradation. For example, the composition of Example 1 is sprayed onto the inkide and then again subjected to a cohesive spray of the type shown above without mist to reduce evaporation.

This makes it 'easier' to wet the screen and keep the ink wet for a period of time. However, if the emulsion is taken to the screen shop for complete removal, it tends to dry out and some may run down the print side of the screen. In such cases, after treatment with the composition of Example 1 to break up the ink, the composition of Example 2 may be applied on the print side of the screen before contacting the solubilized residue with the water spray. Re-bark to freshen up the above residue. The concentrated solution of Example 2 was screened with Zolin F.
After respraying the contact side and rinsing with water, the emulsion is now sensitized or conditioned for subsequent reaction with an emulsion remover as described above. Additionally, if yeast or haze occurs, a ghost remover may be used as indicated above.

A very important aspect of this cleaning and reclamation method is that it does not require screen degreasing, which is required when typical products useful in the prior art are used on the screen for ink and emulsion removal. Conventionally,
Toluene, acetone, bleach, trisodium phosphate and their low solvents or cleaning agents of the type given in the Background of the Invention have been used to remove oily residues from the screen at the end of processing. As can be seen, the present invention provides a system for completely removing ink and emulsions from printing screens that is highly effective and heretofore unattainable.

From the above detailed description, a printing screen cleaning and rejuvenating composition has been provided which has distinct advantages over previous products.

Additionally, there has been provided a method of using the unique compositions of the present invention that work synergistically with other compositions in the process of cleaning and cleaning screens. Based on the above detailed description, those skilled in the art □S...: It is easy to create modifications from the embodiments and working methods within the scope of the present invention.

Agent Asamura Hao 4 other people

Claims (1)

Claims: (1) A printing screen cleaning composition comprising a non-aqueous dispersion of N-methyl-2-pytetralidone, an oxygenated solvent, and a surfactant. (2) *The composition of claim 1, wherein the chlorination solvent is selected from the group consisting of ptyrse tetrasolde, cepsolzoacetate and cyclohexanone, and mixtures thereof. 3. The composition of claim 1, wherein said surfactant is selected from the class consisting of nonionic, anionic and amphoteric surfactants, and mixtures thereof. (4) A patent claim further comprising an organic solvent selected from the group consisting of methylene chloride, 1.1.1-)chloroethane, dimethyl sulfoxide and triclotrialoethane, and mixtures thereof. The composition according to Range 1. (5) About 60-85% N-methyl-2-virridone, 10-65% in oxygenated solvent? and surfactant rigid 1-5%
A printing screen cleaning composition comprising a non-aqueous dispersion of. 6. The composition of claim 5, wherein the oxygenated solvent is selected from the group consisting of butyl heptalosolp, cellosolzoacetate and Schiff Award hexanone, and mixtures thereof. 7. The composition of claim 6, wherein said surfactant is selected from the class consisting of nonionic, ionic and amphoteric surfactants, and mixtures thereof. (8) The claimed invention further contains an organic solvent selected from the group consisting of methylene chloride, 1.1.1-)ritaproethane, dimethyl sulfoxide and triclotrialoethane, and mixtures thereof. Compositions of Range 5. (9) A printing screen cleaning composition consisting of a non-aqueous dispersion of N-methyl-2-pyridone, an oxygenated solvent and a surfactant, additionally containing a water-dispersible oil. al The above water dispersion lubricant is polyalkylene glycol,
The composition of claim 9 selected from the group consisting of ethoxylated lanolin and ethoxylated castor oil. Treat the ink residue on the printing screen with a liquid composition consisting of N-methyl-2-pyrrolidone, an oxygenated solvent, and an interfacial aging agent, and apply the composition to the ink surface for a sufficient period of time to decompose the ink residue. A method of cleaning a printing screen having ink residues on its surface, comprising the steps of: retaining the ink residue on its surface; and rinsing the decomposed ink residue with a pressurized water stream. 02 Washing water is applied as a fan spray, special f
1. The method according to claim 11. (Claim 131 water washing is pressurized low-water washing,
: Method of Section 11. Claim 11, wherein the 0.11 m bleaching bath agent is selected from the group consisting of butyl cellosolve, cellosolve acetate and cyclohexanone, and mixtures thereof.
Section method. ! l+)t The method according to claim 14, wherein the ink surface retention w1 time is several hours from the time limit. α! After a hold time of several hours, the degraded ink was treated with N-methyl-2-pyrrolidone, an oxygenated solvent,
16. The method of claim 15, wherein the treatment is performed with a concentrated solution of methylene chloride and a surfactant. 12. The method of claim 11, wherein the liquid composition additionally contains an aqueous dispersion. 18. The method of claim 17, wherein said water dispersion lubricant is selected from the group consisting of polyalkylene glycols, ethoxylated lanolin, and ethoxylated castor oil. □ Treat the ink residue of the printing screen with a liquid composition consisting of 19N-methyl-2-pyrrolidone, an oxygenated solvent, and a surfactant for a sufficient period of time to decompose the ink residue. is retained on the ink surface, the decomposed ink residue is rinsed with a stream of pressurized water, the rinsed screen is briefly contacted with a periodate-containing emulsion remover, and the resulting screen is exposed to a stream of pressurized water. 1) The periodate-containing emulsion remover is sodium metaperiodate. Claim 1, which is an aqueous solution of
Method of Section 9. 20. The method of claim 20, wherein the periodate-containing emulsion remover additionally contains an anionic surfactant. (2) The method of claim 19, wherein after the final water flush, a caustic solution of an oxygenated solvent is applied to the screen to characterize the dust image. V, 9m The caustic solution of the bleaching bath agent consists of a solution of an oxygenated solvent selected from the group consisting of sodium hydroxide, cyclohexanone and cellosolve acetate and mixtures thereof and other surfactants. The method of Section 22. (to) The method of claim 26, wherein methylene chloride is added to the caustic solution. - the other surfactant is an anionic surfactant;
The method of claim 19. (b) After the holding time and before the first water wash, the resulting screen residue was treated with N-methyl-2-pyrrolidone, oxygenated solvent, surfactant, and methylene chloride, '1 =
20. The method of claim 19, wherein a composition comprising an organic solvent selected from the group consisting of 1, '1 = ) li-aa-ethane, dimethyl sulfoxide, tric-pO difluoroethane, and mixtures thereof is sprayed.