RU2276173C1 - Composition for taking away lacquer and paint coatings - Google Patents

Abstract

FIELD: protective coatings.

SUBSTANCE: invention relates to chemical methods for taking away lacquer and paint coatings, namely to compositions for removing lacquer and paint coatings, including old ones, from surfaces of ferrous metals, wood, concrete, ceramic, and other surfaces except aluminum surface. Composition according to invention contains, wt %: sodium hydroxide, 10-15; lime milk with content of active calcium oxide at least 266.0 g/dm³, 16-22; thickening agent in the form of limestone meal with CaCO₃ content at least 91.5% and granule size 0.001 to 2.0 mm, obtained as limestone fraction to be fired in soda ash production, 10-18; emulsifier Synterol, i.e. carboxymethylated isononylphenol ethoxylate sodium salt, 0.5-1.0; triethanolamine, 0.2-0.5; and water.

EFFECT: increased composition efficiency, reduced corrosion activity and consumption, facilitated preparation procedure, and utilized soda ash production waste.

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Description

The invention relates to chemical methods for removing paint coatings, and in particular to compositions for removing paint coatings, including old from the surface of ferrous metals, wood, concrete, ceramic and other surfaces (except aluminum), and can be used, in particular, to remove paints from the inner surface of metal containers from under paints, in domestic conditions, at industrial enterprises during the repair and restoration of construction projects, as well as in any field of the national economy.

In industrial conditions, the removal of paintwork can be carried out by mechanical, thermal or chemical methods.

The most common is the chemical method.

A number of compositions are known for removing paint coatings based on organic solvents. The basis of organic washes, as a rule, are solvents and cosolvents (methylene chloride, methyl ethyl ketone, toluene, acetone, ethyl carbitol, etc.). In addition, compositions for removing paint coatings contain a number of functional additives.

As additives, various cosolvents, thickeners, disintegrants, evaporation retardants, emulsifiers and other substances can be used.

A known composition for removing paint coatings according to US Pat. PL 59061 dated 02.16.1970, including methylene chloride, cosolvent (a mixture of toluene and aromatic amine), carboxylic acid (C ₁ -C ₃ ) as a disintegrant, alcohol (C ₁ -C ₃ ), a thickening agent and an evaporation inhibitor - casein and paraffin, emulsifier (a condensation product of ethylene oxide with alcohol) and water. This wash is suitable for use only in bathtubs by dipping, as it is an emulsion.

A known composition for removing a graphic image from synthetic papers and films, including, wt.%: Fine chalk, ethyl alcohol, aerosil, a surfactant (ethoxylated fatty alcohols with a degree of hydroxyethylation 10 (DS-10), water [AC SU 1090698, IPC C 09 D 9/04, 1984].

The composition removes only the pencil image and information printed with a limited range of ink.

Known composition for removing paint coatings containing methylene chloride as an active solvent, co-solvent - ethyl alcohol, vaporization inhibitor - paraffin, disintegrant - acetic acid, corrosion inhibitor - urotropine, thickener - aerosil and derivatives of dialkyl polyethylene glycol ether phosphoric acid. RU 2041901, IPC C 09 D 9/04, 1992].

The disadvantages of the composition are the low rate of removal of coatings, technological difficulties in use due to the use of solid insoluble thickener in the system, and the inaccessibility of a number of ingredients.

The disadvantages of this method include the lack of effectiveness and fire hazard.

Known composition for removing paintwork containing an organic solvent, such as acetone, white spirit with the addition of ethyl alcohol and diluted phosphoric acid [US Pat. RU 2058352, IPC C 09 D 9/04, 1992].

The disadvantages of this composition include its high consumption and the duration of cleaning.

Also known is a composition for removing paint coatings containing methyl ethyl ketone, acetone, toluene as cosolvents, polyvinyl chloride as a thickening agent, paraffin as an evaporation inhibitor, acetic acid as a disintegrant and N-methyl-α-pyrrolidone as a solvent [US Pat. RU 2101312, IPC C 09 D 9/04, 1995].

The disadvantages of this composition include high volatility and lack of effectiveness.

A known composition for removing a graphic image from film materials containing monohydroxy aliphatic alcohol (isopropyl or ethyl alcohol), acetone, glycerin, aliphatic unsaturated aldehyde, as a nonionic surfactant - ethoxylated monoalkylphenols based on propylene trimers (neonol AF 9-10, AF 9-12 in an amount of 0.025-0.03 wt.%), Water [US Pat. RU 2103297, IPC C 09 D 9/04, 1996].

The composition is designed to remove the applied information from synthetic, phototechnical and diazotypic substrates and removes elements made with pencil, ink, paint, domestic and foreign production.

A known composition for removing paint coatings containing methylene chloride, toluene, formic acid, paraffin, a mixture of polyvinyl chloride and a copolymer of vinyl chloride with vinyl acetate (VA-15) in a mass ratio of 2.5: 1.0 as a thickener and polyethylene oxide as a surfactant, and additionally contains phenol as a stabilizer [US Pat. RU 2200750, IPC C 09 D 9/04, 2001].

Although this composition is quite effective, it contains dangerous products, such as formic acid, phenol, toluene, which requires great care when working with this composition.

A known composition for removing paint coatings containing methylene chloride, ethylcarbinol or VAT residue from the production of benzyl alcohol, or a mixture thereof, paraffin, acetic acid, urotropin, as a thickener and vaporization inhibitor, high molecular weight waste A-25 (3.0-15.0 wt. .%). The composition may additionally contain an emulsifier - the product of processing a mixture of mono- and dialkylphenols OP-7 or OP-10 (0-1.5 wt.%) Or VAT residue of methylene chloride production (0-5.0 wt.%) [US Pat. RU 2219209, IPC C 09 D 9/04, 2001].

A known composition for removing paintwork based on glyphthalic resin (US Pat. RU 204556 from 02/01/1993), containing wt.%: Butyl alcohol 2.5-11; paraffin 0.5-1; toluene 9-11; dioxane 1.4 0.2-1.0; triethanolamine 0.2-0.5; urotropin 0.5-1.5; methylene chloride up to 100.

Significant disadvantages of these compositions (washes) are their fire hazard, which limits the scope of their application, the complexity of their use on vertical surfaces and high volatility.

Known methods for removing coatings based on the use of alkaline compositions.

For example, there is a known method of removing writing composition, where inorganic bases of the KOH type are used in the amount of 0.5-1% as a solvent, and organic high-molecular-weight surfactants of the OS-20 or TWIN-80 type are used as a catalyst [US Pat. RU to the application No. 2002123933, IPC C 09 D 9/04, 2002].

A known composition for removing paint coatings, including sodium hydroxide, quicklime, chalk and water in the following ratio, wt.%: Sodium hydroxide 4-7; quicklime 12-25; chalk 6-10; water 50-80 [Itsko E.F. Removing paintwork. - Leningrad, 1991 - p.45].

The disadvantages of this composition are the insignificant removal rate of paint coatings from 30 minutes to several hours, heating to 80-110 ° C is required, a large consumption of the composition for washing is 300-600 g / m ² . The composition removes only coatings (VL-725) from metal surfaces.

A known composition for removing paint coatings from the inner surface of a metal container from under paints is a 4-6% solution of caustic soda [magazine “Paint and varnish materials and their use. M.: Chemistry, 1981. No. 3].

This solution provides a complete washing of the inner surface of only those containers in which there were residues of fresh liquid paint.

The disadvantages of the composition should also include its unsuitability for removing dried paint residues from a metal surface.

A known composition for removing paint coatings from metal surfaces, including alkali metal oxide hydrate, alkali metal nitrite, alkali metal nitrate, alkali metal borohydrite and the rest is water [A C.SU No. 633884, IPC C 09 D 9/04, 19.73].

The composition removes coatings on the basis of a doped polyvinyl alcohol. This composition is relatively expensive due to the high cost and inaccessibility of a number of ingredients.

A known composition for removing paint coatings containing alkali metal hydroxide, an accelerating additive - Rochelle salt and water [A.C.SU No. 767159, IPC C 09 D 9/04].

The disadvantage of the composition is the increased temperature of removal of coatings at a sufficiently high concentration of alkali.

A known composition for removing paintwork, mainly old paint, including sodium hydroxide, quicklime, powdered chalk, water, and additionally contains kerosene and detergent for dishes "Drop" [US Pat. RU to the application No. 2001128841, IPC C 09 D 9/04, 2001].

The disadvantage of this composition is the use of a flammable additive - kerosene. The composition removes coatings at a sufficiently high concentration of alkali.

The closest composition for removing paint coatings (prototype) is a composition containing sodium hydroxide, lime component - quicklime, filler - soda ash, thickener - chalk, emulsifier - polyethylene oxide, water in the following ratio, wt.%:

Alkali metal hydroxide 3-5 Quicklime 25-30 Soda ash 5-10 a piece of chalk 3-5 Polyethylene oxide 0.5-1 Water Rest

[US Pat. RU 2204577, IPC C 09 D 9/04, 2000].

The disadvantages of the composition of the prototype should include:

- the complexity of the preparation of the composition due to the curing of at least three days of quicklime with water;

- the dissolution of sodium hydroxide and soda ash gives a significant exothermic effect;

- insufficiently high efficiency of the composition;

- the difficulty of transporting and dosage of quicklime;

- corrosive effect of the composition.

The task of the invention is to increase the effectiveness of the composition for removing paint coatings, reducing its corrosiveness, consumption, improving the manufacturability of the composition, recycling waste from the production of soda ash.

This object is achieved in that the proposed composition for removing paint coatings, including sodium hydroxide, lime component, thickener, filler, emulsifier, water, contains lime milk with a mass fraction of calcium oxide of active CaO, not less than 266.0 g / dm ^3, as a thickener using limestone flour with a content of CaCO ₃ is not less than 91.5 wt% and a particle size of from 0.001 to 2.000 mm -. departure limestone fractions were applied to the firing in the production of soda ash, in qual TBE emulsifier used sodium salt of carboxymethylated ethoxylate izononilfenola (sinterol) as filler sodium tripolyphosphate (TPF) and triethanolamine further comprises the following component ratio, wt.%:

Sodium hydroxide 10-15 Milk of lime 16-22 Limestone flour 10-18 Sinterol 0.5-1.0 Sodium Tripolyphosphate 2-3 Triethanolamine 0.2-0.5 Water Rest

As sodium hydroxide use "Technical caustic soda" according to GOST 2263-79.

The use of GOST's sodium hydroxide solution eliminates the stage of dissolution of solid NaOH.

In the production of soda ash, limestone is used as a carbonate feed to produce lime and carbon dioxide.

Limestone is a solid rock, which is subjected to crushing to obtain conditioned raw materials and then served for firing.

A smaller fraction - 20-40 mm - is a waste of the limestone fraction, which currently does not find wide qualified application, it is mainly used as crushed stone.

Limestone flour is obtained by grinding carbonate rocks and represents the screening of their crushing in the production of crushed stone, which also does not find qualified use - they are used when strewing roads with ice.

We use limestone screenings with particle sizes from 0.001 to 2.0 mm

Screening of crushed stone of limestone corresponds to TU 5711-044-00204872-2002. Mass fraction of calcium carbonate,% not less than 91.5.

The active limestone component is obtained by calcining limestone. The resulting lime - calcium oxide - is quenched with excess water to produce milk of lime. Milk of lime is used in the main process for producing soda ash for the regeneration of ammonia in the construction, chemical and other industries.

In the present invention, milk of lime is used in accordance with TU 2133-21-00204872-2003.

In terms of quality, milk of lime should comply with the standards: the mass fraction of active calcium oxide (CaO act) is at least 266.0 g / dm ³ and the density is at least 1.24 g / cm ³ .

To ensure the stability of the composition and removal of coatings, sinterol, which is a highly effective surface-active substance (SAS) with increased biodegradability, was introduced into the composition.

Synterol selected as a surfactant reduces surface tension and thereby improves the wettability of the treated surface, accelerating the transfer of contaminants into the solution, and also helps to remove paint coatings and various kinds of contaminants (metal oxides, salts, oil and grease deposits) from metal and other surfaces, which facilitates peeling of the coating from the surface and enhances the action of the composition.

The sodium salt of carboxymethylated isononylphenol ethoxylate (synterol) TU 2428-031-0151489-94 is a compound of the general formula: RC ₆ H ₅ -O (C ₂ H ₄ O) _n CH ₂ COONa, where R is isononyl; n - 6, 10, 12.

Distinctive features of the proposed composition for removing paint coatings from the known (prototype) are the additional introduction of sodium tripolyphosphate and triethanolamine.

The active part of the composition for removing LCP includes sodium hydroxide, milk of lime and sodium tripolyphosphate.

The introduction of sodium tripolyphosphate as a chemical reagent contributes to an increase in the efficiency of solution penetration into the LCP, while the adhesion strength of the LCP is most rapidly reduced and, thereby, its removal time is reduced. In addition, a phosphate film is created on the metal surface after removal of the old paintwork. When the object is repainted, a phosphate film promotes good absorbency of the paint materials and thereby improves their adhesion; on a non-phosphatized metal, rust quickly spreads under the paint film.

Tripolyphosphate is not harmful to health. The effective action of tripolyphosphate makes it a valuable addition to the composition.

Technical sodium tripolyphosphate according to TU 2148-037-0019441-02 is a free-flowing white powder with a mass fraction of sodium tripolyphosphate of at least 94%. The chemical formula of Na ₅ P ₃ O ₁₀ .

The alkali-based paint remover can cause oxidation of the metal surface and corrosion damage.

To ensure stability and reduce corrosion activity, a film-forming amine, triethanolamine, was introduced into the composition.

In the proposed composition, triethanolamine is used as a secondary surfactant that enhances the ease of removal of the coating, and also as a corrosion inhibitor, corresponds to TU 2423-096-05766575-2000. Formula of triethanolamine C ₆ H ₁₅ NO ₃ .

The composition for removing paint coatings is easy to prepare. The technology of preparation of the composition consists in sequential mixing with stirring of all its constituent components.

Initially, sodium hydroxide in the form of a 42% solution of NaOH (caustic) is mixed with milk of lime, then sodium tripolyphosphate, sinterol, triethanolamine are added and then limestone flour is added. All mixed to a homogeneous creamy mass in the presence of water.

The method of applying the composition is simple: on a surface with an old paint and varnish coating, the wash is applied with a spatula, synthetic brush, roller or dipping into the bath, after exposure the swollen film is removed with a rag, scraper or rinsed with water.

The quality of the composition is determined by experimental immersion of samples with LCP in the proposed composition with a different ratio of the starting components by dipping.

The removal efficiency is estimated by the rate of removal of the coating from the surface of the sample — the removal time in minutes, at room temperature 20 ± 5 ° C.

There should be no signs of metal corrosion on the treated metal surface. The proposed composition determine the flow rate of washing per unit of the treated surface.

Compositions for removing paint materials with the claimed ratio of components and the known composition of the prototype US Pat. RU 2204577 dated 11/14/2000 are presented in table 1.

The proposed composition effectively destroys coatings based on the following film-forming agents: cellulose nitrite (for example, NTs-132), oil paints (for example, MA-15), pentaphthalic resin (for example, PF-115 enamel), glyphthalic resin (for example, GF-230 ) and others.

Table 2 shows comparative data on the effectiveness of the action and consumption of the tested compounds.

From the above data it follows that the proposed composition is not inferior to the prototype, in some respects even better - the time for removing the paintwork is reduced, while the consumption of the composition is reduced or remains equal to the consumption of the composition of the prototype.

After treatment with the composition, the metal surface is clean without signs of corrosion, since a protective film forms on the metal surface.

The proposed composition can be used to remove various types of coatings from different surfaces at room temperature.

Thanks to the established selection and combination of its components, the proposed composition allows you to quickly remove paint and varnish coatings and is not inferior to the prototype, and in some respects even better, for example, in terms of consumption.

Thus, the application of the proposed structure will allow:

- reduce the time of removal of the paintwork at a lower flushing rate;

- Dispose of waste in the production of soda ash (screening of crushed stone);

- use the intermediate product Ca (OH) ₂ (milk of lime) in the production of soda ash;

- use liquid sodium hydroxide (42% NaOH solution), excluding the stage of dissolution of solid 100% NaOH;

- reduce the corrosion activity of the composition.

Table 1. Components, wt.% Known composition of the prototype Example example 2 one 2 3 Sodium hydroxide (hard, flaky or fused) four - - - Sodium hydroxide - 42% NaOH solution - 10 12.5 fifteen Milk of lime with a CaO content of at least 266.0 g / dm ³ - 16 18.5 22 Sodium Tripolyphosphate - 2 2,5 3 Quicklime 27.5 - - - Soda ash 7.5 - - - a piece of chalk four - - - Screening of limestone crushed stone (fraction 0.001-2.0 mm) - 10 fourteen eighteen Triethanolamine - 0.2 0.35 0.5 Sinterol - 0.5 0.75 1,0 Water rest rest rest rest

Table 2. Structure Type of paintwork The processed surface Coating Removal Time, min Flushing rate, g / m ² Corrosive effect one MA-15 metal 1-1.5 150-180 absent and etc. wood 5-6 200-220 - 2 MA-15 and metal 2-2.5 110-130 absent other wood 8-10 180-200 - 3 MA-15 and metal 4-6 100-120 absent other wood 12-14 140-180 - one PF-115 metal 2.5-3 130-160 absent wood 14-18 200-220 - 2 PF-115 metal 5-7 100-130 absent wood 16-18 180-200 - 3 PF-115 metal 7-9 100-120 absent wood 20-22 130-150 - one NTs-132 metal 4-5 150-180 absent 2 NTs-132 metal 5-7 130-150 absent 3 NTs-132 metal 7-9 100-130 absent one GF-230 metal 3-5 150-160 absent 2 GF-230 metal 5-6 160-180 absent 3 GF-230 metal 6-7 160-180 absent Famous PF-115 metal 6-8 130-150 - composition by wood 20-25 200-220 prototype MA metal 2.5-3 120-150 - fifteen wood 10-12 190-210

Claims (1)

A composition for removing paintwork, including sodium hydroxide, milk of lime with a mass fraction of active calcium oxide (CaO act.) Of at least 266.0 g / dm ³ , limestone flour with a CaCO ₃ content _of at least 91.5 wt. % and particle sizes from 0.001 to 2.0 mm — waste of the limestone fraction supplied for calcination in the production of soda ash, as an emulsifier — sodium salt of carboxymethylated isononylphenol ethoxylate — sinterol, and filler — sodium tripolyphosphate, and also contains t ietanolamin and water in the following ratio, wt.%: Sodium hydroxide 10-15 Milk of lime 16-22 Limestone flour 10-18 Sinterol 0.5-1.0 Sodium Tripolyphosphate 2-3 Triethanolamine 0.2-0.5 Water Rest