MXPA97009587A - Composition to remove paints, varnishes or the - Google Patents

Abstract

The present invention relates to: This composition for pickling paints, lacquers or primers, is characterized in that it consists of or comprises: (A) from 5 to 90 parts by weight of water; (B) from 2 to 47.5 parts by weight of benzyl alcohol (C) from 2 to 47.5 parts by weight of dimethyl sulfoxide or of N-methylpyrrolidone, (A) + (B) + (C) represents 100 parts by weight

Description

COMPOSITION TO REMOVE PAINTS, VARNISHES OR LACQUERS FIELD OF THE INVENTION The present invention relates to a composition for stripping or pickling from a substrate coatings of paint, varnishes or lacquers that are on it, such as metals and wood.

BACKGROUND OF THE INVENTION In the industry of industrial pickling, blinds, windows, doors and radiators receive a pickling process, like any mechanical component (for example: wheel cubes, squats, etc.). The industrial pickling of paints and the like is carried out by immersing the components that will be pickled in a liquid bath formulated under hot or cold conditions, it is possible that this liquid bath is agitated or not agitated. The components are left in the bath for a certain period until the pickling is achieved (the degradation or removal of the paint depends on the systems). Then, the components are removed from the bath and rinsed with a jet of pressurized water ("carcher"), the flakes or clumps of paint will then be removed by the pressure of the water jet. When the bath contains an I 1 flß / > 7M strong NaOH type base, a neutralization operation is carried out in an acid bath consisting of a solution of sulfuric or hydrochloric acid. The formulations currently used in industrial pickling are either chloride based or alkali based. The baths or chloride formulations are mixtures based on methylene chloride, methanol (5 to 10% by weight) and aromatic compounds (toluene, xylene in a proportion of a few percentage points). These mixtures may also contain activators, which may be acidic (such as formic acid) or basic (such as, for example, monoethanolamine). Chloride baths are used cold because methylene chloride is very volatile and the odor that it gives off is very suffocating. The pickling action occurs by the removal of the paint with flaking. Industrial pickling technicians usually want to replace chloride with a substitute for environmental reasons. Baths or alkaline formulations are essentially based on sodium hydroxide in water to which sodium glycolate, complexing agents and wetting agents are added. The mixtures are used in hot, at a temperature of approximately 50 ° C to 100 ° C and, the pickling time is reduced by half for every 20 ° C increase in t? t / 'i7M: -: the temperature .. the mechanism of action is totally different from that of the chloride formulations since these formulations degrade the paint by reacting the sodium hydroxide with the polymer. In particular, with glycerophthalic paint and alkyd paints, the saponification of the ester functions takes place, which degrades the paint, reducing it to dust. When dispersed in the bath, this dust forms a mud, which the pickling technicians hate. This mud is virtually infiltrable (blocker). In addition, alkaline formulations are less effective on other types of paints (epoxy, polyurethane, etc.). the technicians in industrial pickling, also want in this way, to find a substitute formulation with greater versatility that does not lead to the degradation of the paint.

SUMMARY OF THE INVENTION The applicant company has thus investigated novel pickling formulations for paints, varnishes or lacquers, which satisfy the present needs described above and constitute valuable formulations in order to be able to advantageously replace the known chloride and alkaline formulations. ! lr ^ H / ') 7M7 DETAILED DESCRIPTION OF THE PREFERRED MODALITIES The novel pickling composition according to the present invention satisfies these objectives characterized in that it consists of or comprises: (A) from 5 to 90 parts by weight, preferably 10 to 80 parts by weight of water; (B) from 2 to 47.5 parts by weight, preferably 5 to 45 parts by weight, of benzyl alcohol; (C) from 2 to 47.5 parts by weight, preferably 5 to 45 parts by weight, of dimethyl sulfoxide or of N-methylpyrrolidone, (A) + (B) + (C) represent 100 parts by weight. The proportion of water that can be primary, makes this composition a very advantageous formulation in terms of cost. The pickling composition according to the invention may also comprise: (D) at least one activator, which can be chosen in particular from monoethanolamine (MEA), triethanolamine (TEA), formic acid, pyrrole, TEA / acid mixtures formic, benzaldehyde, mixtures of MEA / benzaldehyde and alkali metal hydroxide such as for example sodium hydroxide (NaOH), in a particular proportion of from 0.1 to 10 parts by weight per 100 parts by weight of (A) + (B ) + (C). t l ', "M /' 7MX Preferred activators are mixtures of MEA / benzaldehyde (in particular, 1 part by weight of MEA and 2 parts by weight of benzaldehyde), benzaldehyde and NaOH. The pickling composition according to the invention may further comprise: (E) at least one surfactant, in a particular proportion of from 0.1 to 10 parts by weight per 100 parts by weight of (A) + (B) + (C); examples of nonionic surfactants include the ethoxylated surfactants of the "Metox" series, sold by the company "SEPPIC" (for example, the ethoxylated methyl ester fraction comprising 20 ethylene oxide units "Metox 20 EO"); as an example of ionic surfactants may be mentioned sodium dodecyl sulfate; (F) At least one thickener selected in particular from acrylic thickeners, in a particular proportion of from 0.1 to 10 parts by weight per 100 parts by weight of (A) + (B) + (C); as specific examples of acrylic thickeners, mention may be made of acrylic resins sold under the name "Carbopol" by the company Goodrich, BF, Co., whose production process is described in the United States of America patent US-A-4,419,502 , entitled "Polymerization process for carboxyl-containing poly ers". In accordance with a particular modality

[0111] Advantageous of the present invention, the pickling composition does not comprise neither surfactant nor thickener and, in this case, is in the form of an unstable emulsion. According to two other embodiments of the present invention, the pickling composition comprises at least one surfactant and no thickener, and in this case is in the form of a microemulsion or comprises at least one thickener and no surfactant and is in the form of a thickened emulsion. The present invention also relates to a process for pickling paints, lacquers and varnishes applied to a substrate, using a pickling composition as defined above, characterized in that the substrate is immersed in a bath that is optionally heated (e.g. to a temperature between 40 and 70 ° C) and the pickling composition is optionally stirred when it is in the aforementioned unstable microemulsion or emulsion form, for a time which is sufficient to effect the removal of the paint, varnish or of the lacquer or, in which a pickling composition in the aforementioned thickened emulsion form is applied to the substrate and allowed to act for a time which is sufficient to effect the removal of the paint, varnish or lacquer.

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The following examples illustrate the present invention, without however limiting its scope. In these examples, the percentages of the compositions are given based on weight.

EXAMPLE 1: UNSTABLE EMULSION An unstable emulsion was prepared for pickling, formulated as follows: Water 78% Benzyl alcohol 11.6% Dimethyl sulfoxide 10.4% 100% By mixing these three ingredients by bubbling, an unstable milky emulsion was formed in which there was no phase shift or separation for at least one hour. A substrate of phosphate-treated steel coated with a polyester lacquer (Glacier White 389 by Herberts), sold or the company Etalon, was immersed in a bath of this emulsion, bringing it to 50 ° C with agitation. The pickling required 20 minutes.

EXAMPLE 2: MICROEMULSION A pickling microemulsion was prepared, formulated as follows: Water 77.3% Benzyl alcohol 12% Dimethyl sulfoxide 10.7% 100% Sodium Dodecyl Sulfate: 3.1% By mixing these ingredients, a completely transparent microemulsion was obtained which is mixed with water, which had only a very weak color to solvents. The pickling test was carried out under the same conditions as in Example 1, but without stirring the bath. The pickling required 38 minutes.

EXAMPLE 3; THICKENED EMULSION A thickened pickling emulsion was prepared, formulated as follows: Water 78.1% Benzyl alcohol 11.5% Dimethyl sulfoxide 10.4% 100% acrylic thickeners sold under the name "Carbopol E22" by the company "Goodrich", 2.8%. a mixture was obtained which has the appearance of a "dense or thick milk" totally homogeneous that did not separate even after several weeks. An etching test was carried out by applying this mixture to a phosphate-treated steel coated with a [I HÍ • i-'MX polyester lacquer (Herberts Glacier White 389), sold by the company Etalon, at room temperature (20 ° C). The pickling required 360 minutes.

EXAMPLE 4 TO 7 Four formulations of the unstable emulsion type were prepared, as indicated in Table 1. The pickling was carried out under the conditions of Example 1. The results are provided in Table 1.

TABLE 1 Composition Example 4 Example 5 Example 6 Example 7 Water 78.8% 79.5% 79.5% 79.30% Benzyl alcohol 11.1% 10.25% 10.25% 10.35% Dimethyl sulfoxide 10.1% 10.25% 10.25% 10.35% 100% 100% 100% 100% Monoethanolamine 1% 1% 3.10% Benzaldehyde 2.6% 2% Pickling time (min) 7 3.3 2 100 EXAMPLE 8 TO 12 The following base formulation for a microemulsion was prepared: > "Water 78.1% Benzyl alcohol 11.5% Dimethyl sulfoxide 10.4% 100% sodium dodecyl sulfate: 3.1% Five microemulsions were prepared by adding 1% of an activator to the formulation as indicated in Table 2 below and the pickling tests were carried out as in Example 2. The results of the pickling They are also provided in this box.

TABLE 2 EXAMPLES 13 TO 16 The four thickened pickling emulsions were prepared as indicated in Table 3. The pickling was carried out under the conditions of Example 3. The results are also given in Table 3.

'M' I7MX TABLE 3 Composition Example Example Example Example 13 14 15 16 Water 78.1% 78.3% 78.1% 78.2% Benzyl alcohol 11.5% 11.4% 11.5% 11.4% Dimethyl sulfoxide 10.4% 10.3% 10.4% 10.4% 100% 100% 100% 100% Thickener 2.4% 5.5% 4.2% 3.7% "Carbopol E22" Pyrrole 1% Formic acid 1% 5.25% TEA / formic acid 4.2% Pickling time (min) 240 210 70 1.0 EXAMPLE 17: UNSTABLE EMULSION An unstable pickling emulsion was prepared, formulated as follows: Water 78 Benzyl alcohol. 11 N-methylpyrrolidone 11 100 The process was carried out as in Example 1. The pickling required 19 minutes 30 seconds.

GLG, HH / '> 7MX EXAMPLE 18 An unstable emulsion type formulation having the composition indicated below was prepared: Water 78.30% Benzyl alcohol 10.85% Dimethyl sulfoxide 10.85% 100% Sodium Hydroxide 8.7% A plate made of XC45 phosphate treated steel coated with epoxy powder was immersed in a bath of this emulsion, brought to 50 ° C with agitation. The pickling required 10 minutes. '' > ? MX

Claims (11)

1. NOVELTY OF THE INVENTION Having described the present invention, it is considered as a novelty and, therefore, the content of the following CLAIMS is claimed as property: 1. The composition for pickling or peeling off paints, lacquers or primers, characterizes because it consists or comprises: (A) from 5 to 90 parts by weight of water; (B) from 2 to 47.5 parts by weight of benzyl alcohol; (C) from 2 to 47.5 parts by weight of dimethyl sulfoxide or N-methylpyrrolidone, (A) + (B) + (C) represents 100 parts by weight. The composition according to claim 1, characterized in that it consists of or comprises: (A) from 10 to 80 parts by weight of water; (B) from 5 to 45 parts by weight of benzyl alcohol; (C) from 5 to 45 parts by weight of methyl sulfoxide or N-methylpyrrolidone. 3. The composition according to any of claims 1 and 2, characterized in that it also comprises: 1G '- "/' I7MX (D) from 0.1 to 10 parts by weight, per 100 parts by weight of (A) + (B) + (C), of at least one activator 4. The composition according to claim 3, characterized in that the activators are chosen monoe anolamine, triethanolamine, formic acid, pyrrole, mixtures of TEA / formic acid, benzaldehyde, mixtures of MEA / benzaldehyde and alkali metal hydroxide 5. The composition according to claim 4, characterized in that the activator is a mixture monoethanolamine / benzaldehyde, benzaldehyde or sodium hydroxide 6. The composition according to any of claims 1 to 5, characterized in that it also comprises (E) at least one surfactant, in a proportion of from 0.1 to 10 parts by weight per 100 parts by weight of (A) + (B) + (C) 7. The composition according to any of claims 1 to 6, characterized because t it also comprises: (F) at least one thickener selected in particular from acrylic thickeners, in a proportion of from 0.1 to 10 parts by weight per 100 parts by weight of (A) + (B) + (C). 8. The composition according to any of claims 1 to 7, characterized in that it comprises neither a surfactant nor a thickener and is in the form of an unstable emulsion. The composition according to any of claims 1 to 6, characterized in that it comprises at least one surfactant and no thickener and, because it is in the form of a microemulsion. The composition according to any of claims 1 to 5 and 7, characterized in that it comprises at least one thickener and no surfactant and because it is in the form of a thickened emulsion. 11. The process for stripping a paint, paint, varnish or lacquer applied to a substrate, in a bathroom that. optionally it is heated and, optionally stirred, a composition as defined in any of claims 8 and 9, for a time which is sufficient to effect the removal of the paint or, because it is a thickened emulsion as defined in the claim 10, it is applied to the substrate and left to work for a time that is sufficient to effect the removal or removal of the paint. "H / 'I7MX