SE438162B - PROCEDURE FOR CLEANING A SURFACE, IN PARTICULAR REMOVAL OF COATING LAYERS AND LAYOUTS FROM A SURFACE - Google Patents

Description

79046884: 2.

The lower content limit of glycerol is preferably 7%. The upper limit of glycerol is preferably 20% and especially 15%. The lower content limit for water is preferably 30%, especially 50% and in some cases 60%. The upper water content limit is preferably 80%.

A preferred composition is 10 - 30% ethyl acetate, 5 - 20% glycerol and so - so% water. A particularly advantageous composition contains 15 - 25% ethyl acetate, 7 - 15% glycerol and 60 - 80% water. An example of such a particularly suitable composition is about 20% ethyl acetate, about 10% glycerol and about 70% water. Ethyl acetate and glycerol are suitably used with a mutual weight ratio of 0.1 to 2 parts by weight of glycerol per part of ethyl acetate, in particular 0.1 to 1 part by weight of glycerol per part of ethyl acetate and preferably 0.3 to 0.7 parts by weight of glycerol per part by weight of ethyl acetate.

The surfactant may be any suitable anionic, cationic, nonionic or zwitterionic surfactant, preferably in an amount of 0.000l - 5% by weight, based on the total weight of ethyl acetate, glycerol and water or ethyl acetate, glycerol, water and surfactant. The amount by weight of surfactant is preferably 0.0005 - 0.1% by weight and in particular 0.001 - 0.1% by weight.

A variety of different types of the indicated surfactants are well known to those skilled in the art and can be used in accordance with the invention. In this regard, reference is made to well-known literature in the field, for example, "Surface Active Agents" by AM Schwartz and JW Perry, and "Surface Active Agents and Detergents" by AM Schwartz, JW Perry and J. Burch, Interscience Dublishers, New York, London. - '' u .rm; 7904688-ë 3 When the cleaning composition is used continuously, it is supplemented with consumed constituents in such a proportions ratio that the desired composition is maintained.A normal proportions of the constituents of this supplementing solution or activator are approx. 50-95% by weight of ethyl acetate, based on the total weight of ethyl acetate and glycerol, preferably about 60-90% by weight of ethyl acetate, in particular 70-85% by weight of ethyl acetate and especially about 80% by weight of ethyl acetate.

Usually the detergent is at least two-phase, it being convenient to use the detergent in the form of an emulsion of one phase in the other or possibly a double emulsion. The emulsion can possibly be stabilized with various stabilizers or by heavy atomization, but it is usually not a significant inconvenience if the emulsion is unstable and decomposes within a certain period of time. The emulsion can be prepared by means of ordinary stirring means or by spraying.

The treated surfaces are suitably brought into contact with the cleaning agent during simultaneous or subsequent mechanical processing, for example by spraying under a certain pressure or brushing or other mechanical action on the surfaces, for example the action of ultrasound or the action of particles suspended in the solution or by subsequent blasting or other mechanical impact.

In particular when using a two-phase or multi-phase mixture, loose solid or liquid constituents, in particular paint flakes or paint particles, may prove to be difficult to separate from the detergent and, for example, remain at a phase limit in the detergent, which may be due to non-wetting. or poorly wetted by an underlying heavier phase. To facilitate the separation of solid constituents from the cleaning liquid, heavy particles capable of adhering to solid constituents to be separated can be added, for example finely divided rocks, such as finely divided talc. These added solid QUÅLÉTY 79046884 »4 particles act as a weighting agent and cause loosened particles floating in the treatment liquid to be weighed and precipitated to the bottom of the cleaning liquid and can be drained, for example, through a bottom opening in a treatment vessel or storage vessel for the cleaning agent. Other methods of separating solid suspended particles can also be used, for example filtration, centrifugation, vibration treatment or ultrasonic treatment for mechanical separation of adherent light liquid, etc.

When using weighting agents for precipitating suspended solids, the weighting agent may be surface treated, for example made hydrophobic or hydrophilic, to facilitate adhesion to the suspended particles and wetting with an underlying heavier phase. An example is talc or clay that has been hydrophobized.

The particle size of the talc can, for example, vary within the size range up to 1 mm, preferably up to 0.1 mm.

Instead of using an emulsion of two or more phases for cleaning, the cleaning can be carried out in two or more steps and in each step treat the surface with one of the phases in question, for example a phase which is rich in ethyl acetate and preferably also contains glycerol and water, as well as a phase which is rich in water and preferably also contains glycerol and some ethyl acetate. The treatment with these two phases can be carried out, for example, with the special conditions mentioned above, ie. mechanical impact, spraying, etc.

As mentioned above, the invention is useful in cleaning printing equipment, for example the screen printing form. This shape consists of a fine-mesh cloth stretched on a frame. The fabric is usually made of silk or nylon and can have about 200 threads per cm. The fabric is provided with a stencil, which consists of a water-soluble material (resin) in the form of a pattern to be printed. The fabric will thus consist partly of printing and partly of non-printing surfaces.

A substrate is applied under the frame and paint is spread and pressed through the fabric with a so-called squeegee, after which the cloth is removed and the paint is allowed to dry on the substrate. The paint used is usually oil-soluble and the stencil is insoluble in the paint.

After printing, the cloth must be cleaned partly from paint and partly from stencil. According to the invention, it has been found possible to very effectively clean such cloths containing both paint and stencil with the aforementioned cleaning agent and preferably with the conditions otherwise stated.

After washing with the detergent, it is convenient to subject the cloth to a post-wash with aqueous liquid, in particular rinsing with high-pressure water to remove stencils and paint residues.

The constituents ethyl acetate and glycerol can each be replaced by or replaced by other substances with similar properties.

The ethyl acetate can thus be completely or partially replaced by other esters, ethers, aliphatic hydrocarbons, aromatic hydrocarbons, halogenated, preferably chlorinated and / or fluorinated hydrocarbons, ketones, preferably with such solvents which are insoluble in water or have low solubility in water, preferably with a solubility of not more than 20%, preferably not more than 10% and possibly not more than 1% in water. Preferably the ethyl acetate is replaced to a maximum of 80% by weight, in particular not more than 50% by weight and especially not more than 25% by weight, for example not more than 15% or more than 5% by weight with one or more of these other solvents. Examples which may be mentioned are the following solvents: Aliphatic hydrocarbons, preferably in the boiling range ßo - 140 ° C, e.g. eo - 95, s , dichloroethane, tetrachloroethane, trilloretylene, monochlorobenzene, alcohols such as methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, isanol, sec-butanol, amyl alcohol, methyl isobutylcarbinol,, .narln H "of f'v" '.' * "'" F ”* my' _ 14, th '-Mj:» ce .. .- 1904688-ug 6 hexyl alcohols, heptyl alcohols, ethylhexanol, nonanol, benzyl alcohol, cyclohexanol, methylchlorhexanol, diacetone alcohol, acetone, acetone oils, methyl ethyl ketone, methyl isobutyl ketone, mesityloxide, ethyl i-amyl ketone, diisobutyl ketone, cyclohexanone, methyl cyclohexanone, dimethylcyclohexanone, cyclohexenone, methylcyclohexenone, isophorate, amylformyl, amylformyl, methylformyl 1-acetate, n-butyl acetate, isobutyl acetate, sec-butyl acetate, amyl acetate, isohexyl acetate, isoheptyl acetate, cyclohexanol acetate, methylcyclohexanol acetate, benzyl acetate, methyl propionate, ethyl propionate; n-butylpropionate, ethyl butyrate, propyl butyrate, isobutyl butyrate, n-butyl butyrate, amyl butyrate, ethyl lactate, butyl lactate, glycolic acid butyl ester, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, butylene glycol monopropyl monoethyl monopropyl ether, ethyl ethyl polyethyl monopropyl ether, ethyl ethyl ) -monomethyl ether (methoxybutanol), ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, ethylene glycol monobutyrether acetate, butylene glycol (3) -monomethyl ether-1-acetate, ethylene glycol monoacetyl, dimethyl carbonyl, glycol carbonyl; tetramethylene sulfone, carbon disulfide, furfurol.

The glycerol may be substituted in whole or in part by one or more of the compounds mentioned as a substitute for ethyl acetate, preferably those which are soluble in water or a mixture of glycerol and water in the amounts mentioned above. Preferably ambiguous substances are used, and examples of such are cellosolv, glycol ethers, alcohols, keünæm.

Preferably, compositions containing these ingredients are used in proportions such that biphasic or multiphase systems or emulsions are obtained.

The working temperature can be selected arbitrarily below the boiling point at the pressure used. Preferably, a working temperature return below 8000 is used, in particular below 6000 and especially below 40oC. It is convenient to use a temperature above 100 ° C, above 40 ° C and especially above 15 ° C.

The treatment time is adjusted as needed and can be, for example, at least 1 second, preferably at least 10 seconds and in particular at least 1 minute. The upper limit depends mainly on economic considerations and may, for example, be up to 1 day, preferably up to 1 hour, in particular up to one hour and in particular up to 5 minutes.

The treatment according to the invention can be carried out as a cleaning treatment, for example for the removal of paint residues or old paint, but also for the removal of greases and oils, e.g. grease from lubricants or surface treatment, e.g. before subsequent surface treatment by priming, painting, phosphating, chromating, etc. To protect the surface against rusting, anti-corrosion agents can be incorporated into the solvent, for example in the phase containing the main part of the water or in the anhydrous phase or the phase containing a minor part of the amount of water.

Optionally, the aqueous phase may also contain constituents which effect surface treatment, e.g. phosphating, chromating, etc. of a treated metal surface.

The composition, preferably the aqueous phase, may also contain pH adjusting substances, e.g. ammonium and alkali metal salts, e.g. hydroxides, carbonates, silicates, organic bases, preferably for adjusting a basic pH e.g. up to 14, preferably up to 12, usually over 8 and in particular over 9.

The composition may also contain viscosity adjusting and / or emulsion stabilizing agents, such as viscosity enhancing agents, e.g. polymers, such as cellulose-based substances. d 7904168844 Exemnel.

Nylon screen printing cloth mounted on frames used in conventional screen printing was cleaned with the detergent of the invention. The detergent consisted of a mixture of 70% water, 20% ethyl acetate and 10% glycerol and 1% surfactant, based on the weight of the other ingredients.

As surfactants, nonionics were tested; anionic, cationic and zwitterionic surfactants. The detergent was kept in a container in which the screen pressure frames could be immersed. Prior to lowering the frames, the mixture was subjected to vigorous stirring with a propeller stirrer so that a fine dispersion or emulsion of a high ethyl acetate phase in a high water phase was obtained. the emulsion, whereby a rapid release and flaking of the Screen printing frames was immersed in the ink from the frames was obtained. Furthermore, spraying of the emulsion and mechanical processing by brushing were tried in connection with the effect of the emulsion, which further accelerated the removal of the ink from the frames. The frames treated in this way were completely free from printing ink for a period of a few minutes up to 10 minutes. For complete removal of the water-soluble stencil from the frames, these were then treated by spraying water under high pressure.

The composition of the detergent was also varied from the composition specified above D within the limits ï10 6 of the stated contents, whereby equally effective cleaning was obtained.

Furthermore, detergents were tested with the above composition for cleaning metal objects provided with organic coatings of various kinds. These consisted of epoxy paint, linseed oil paint, alkyd paint, acrylate paint, cellulose varnish.

The articles provided with organic surface coating were cleaned by immersion in the detergent after emulsification thereof and by spraying the emulsion of the detergent. In all cases, an effective release of paint was obtained from the substrate, so that the paint was caused to flake off but without the paint dissolving to a liquid state. To facilitate the removal of the paint, mechanical impact was also tested by brushing and by spraying the detergent under high pressure. These measures accelerated the loosening and removal of the paint.

Furthermore, a variation of the composition of the cleaning agent was also tested in this case by 310% as mentioned above, whereby equally effective cleaning was obtained.

To facilitate the removal of the released paint from the treatment liquid, the addition of a weighting agent, which consisted of powdered talc, was also tried. The added talcum powder was deposited on the released paint flakes, whereby their bulk density was increased to such an extent that the paint flakes rapidly sedimented and could be drained from the bottom of the treatment vessel. _______ ø ___ "_______ __........._-- .. i f f" Fm-m cgzïmmrï 79046884: As mentioned above, surfactants or wetting agents are a desirable ingredient in compositions of the invention.

These surfactants can be used in varying amounts depending on the activity of the agents. 0.000l, in some cases 0.01 or 0.1% by weight, but also The lower limit is often higher concentrations may be suitable, such as at least 0.5 or at least 1% by weight. There is usually no upper limit to the content, which is most closely determined by economic considerations and the need to incorporate other ingredients into the compositions. Suitable upper levels may be 10% by weight or 5% by weight, but also lower levels, such as 2 or 1% by weight, may be desirable as in other cases also 0.1% or lower.

Examples of suitable anionic surfactants are alkylaryl sulfonates, preferably having 8 to 18 carbon atoms in the alkyl group, and the alkyl group may preferably be phenyl or naphthyl, for example dodecylbenzene sodium sulfonate, alkali alkyl alkyl sulphates, preferably having 8 to 18 carbon atoms in the alkyl group, e.g. . sodium lauryl sulfate, alkyl sulfonates, preferably having 8 to 18 carbon atoms in the alkyl group, e.g. sodium decyl sulfonate, aryl sulfonates, aryl being preferably phenyl or naphthyl, preferably sodium tetrahydronaphthalene sulfonate, alkali metal salts of fatty acids having preferably 8 to 18 carbon atoms, e.g. sodium stearate, alkali metal lignosulfonates. Sodium alkyl aryl sulfonate has been found to be a suitable surfactant and in the above experiments the anionic surfactants are also used in an amount of 0.1 to 1% active surfactant and preferably 0.2% of active surfactant based on the detergent.

Nonionic surfactants include alkylphenylethylene oxide condensate, in which the alkyl group preferably comprises 8 to 18 carbon atoms and the number of moles of condensed ethylene oxide units ranges from 1 to 100 per alkyl group, for example isooctylphenylpolyethoxyethanol, dodecylphenylpolyethylene glycol, and generally condensate products from acids, alcohols, alkylphenols, amines, amides, etc., such as oxyethylenealkylphenols having a hydrophobic hydrocarbon chain having preferably 8 to 18 or 8 to 12 carbon atoms and a hydrophilic oxyethylene chain having a variable average of oxyethylene groups, for example 3 to 6 oxyethylene groups. Other nonionics are polyoxyethylene thioethers, propylene oxide-ethylene oxide condensate, fatty acid alkanolamides having preferably 8 to 18 carbon atoms in the fatty acid, such as lauric acid alkanolamide, alkyl poly (ethyleneoxy) ethanols, preferably having 8 to 18 carbon atoms in the alkyl group and from 1 to 100 moles fused ethylene oxide per alkyl group, such as tridecyloxy poly (ethyleneoxy) ethanol or ethylene oxide condensate of stearyl alcohol containing about 10 ethylene oxide groups per stearyl group, and polyhydroxyalkyl fatty acid esters such as glycerol monooleate or sorbitan stearate.

Thus, general examples of nonionic surfactants which may be used are polyethyleneoxy ethers of alkylphenols, for example having 6 to 20 or more moles of ethylene oxide and preferably having from 5 to 18 carbon atoms in the alkyl group or groups. The aromatic nucleus may be, for example, benzene, naphthalene or diphenyl. Polyethylene oxyethers of alcohols and mercaptans, preferably aliphatic alcohols and mercaptans having more than 5 carbon atoms are suitable. Difunctional and polyfunctional polyethyleneoxy ethers, polyethyleneoxy esters, for example based on fatty acids of oxidized paraffin wax, polyethyleneoxy compounds with amide bonds and with other bonds are also suitable.

Examples of cationic surfactants which may be mentioned are non-quaternary nitrogen bases, such as nitriles, amines without intermediate bonds, amines with intermediate bonds, such as ester and ether bonds, amide-linked amines, other nitrogen bases, such as imidazoline derivatives prepared by condensation of fatty acid with ethylenediamine, quaternized imidazolines, quaternary nitrogen bases. Examples which may be mentioned are straight-chain alkyl fatty amines having 8 to 18 carbon atoms in the alkyl group, for example dicocosamine, N-alkyltrimethylenediamines having 8 to 18 carbon atoms in the alkyl group, for example N-lauryltrimethyldiamine, higher alkylpyridinium halides having 8 to 18 carbon atoms in alkyl- _. lTY. .POQR QÜEXJ .._......-_...._._...__.___._ .., ___ .. .___ ._., ._. .... ..._____._ .. in the group, for example cetylpyridinium bromide, monoalkyl and dialkylmethyl quaternary ammonium salts having 8 to 18 carbon atoms in the alkyl group, for example monococco trimostril quaternary ammonium chloride and didodecyldimethylquaternary ammonium chloride, quaternary salts with phosphorus-based cation, eg stearamidpropyldimethylahydroxyethylammonium dihydrogen phosphate, fatcyl derivatives of I hydroxylated diamines, for example N- (aminoethyl) 4 ethanolamine in the alkyl group 2 3-dihydroindoles having 8 to 18 carbon atoms in the alkyl group, 2-alkylbenzimidazoles having 8 to 18 carbon atoms in the alkyl group and quaternary salts thereof, 2-alkylquinolines having 8 to 18 carbon atoms in the alkyl group and quaternary salts thereof.

Examples of amphoteric surfactants are those containing carboxy or phosphate esters such as acidic group and non-quaternary nitrogen such as basic group, products prepared by adding fatty amine to acrylic ester, methacrylic ester or croton ester and hydrolysis of the product obtained. , N-higher alkyl-aspartic acid, compounds containing both sulfo groups and non-quaternary amino groups, N-alkyl taurines, monofetacyl derivatives of diamine condensed with lower aliphatic halogenated sulfonic acids, condensation products of alkanesulfonamide with formaldehyde and methylsulfoneurene amines; is attached to an aromatic ring, the reaction product of aromatic aminosulfonic acids with higher alkyl halides and aralkyl halides. Examples which may be mentioned are alkali metal salts of N-coconut aminobutyric acid, cetylpalmitin alkanolamides having 8 to 18 carbon atoms in the alkyl group, natural lecithins, N-coconut aminopropionic acid, polyethoxyamino acid salts having 1 to 100 fused ethoxy groups;

Claims (8)

1; 7904688-4 PATENT REQUIREMENTS A method for cleaning a surface, in particular the removal of coating layers and paint layers from a surface, characterized in that the surface is treated with a detergent containing, by weight, 5-40% ethyl acetate, 5-30% glycerol, 10-90% water and optionally 0.000l-5% surfactant, possibly up to 50% of the amount of glycerol being replaced by one or more other ampholytic substances soluble in the detergent and optionally up to 50% of the amount of ethyl acetate being replaced by one or more more solvents or swelling agents for the coatings to be removed. 2. A process according to claim 1, characterized in that the cleaning agent contains 10-30% ethyl acetate, 5-20% glycerol and 50-90% water. 3. A process according to claim 2, characterized in that the detergent contains 15-25% ethyl acetate, 7-15% glycerol and 60-80% water. A process according to claim 3, characterized in that the detergent contains about 20% ethyl acetate, about 10% glycerol and about 70% water. Process according to any one of the preceding claims, characterized in that the cleaning agent as surfactant contains anionic, cationic, nonionic or zwitterionic surfactant, preferably in an amount of 0.0005-0.1%. Process according to one of the preceding claims, characterized in that a cleaning agent containing viscosity-increasing and / or emulsion-stabilizing substances, preferably polymers, is used. 7. A method according to any one of the preceding claims, characterized in that the cleaning agent is used in the form of an emulsion, preferably prepared by stirring or spraying. 8. A method according to any one of the preceding claims, characterized in that solid particles capable of being bound as a weighting agent are capable of being bound to coatings which are detached from the treated surface and precipitate them, preferably talc or clay.