WO1999037727A1

WO1999037727A1 - Paint stripping composition

Info

Publication number: WO1999037727A1
Application number: PCT/FR1999/000112
Authority: WO
Inventors: Jean-Luc Joye; Jean-Claude Galliot
Original assignee: Rhodia Chimie
Priority date: 1998-01-21
Filing date: 1999-01-20
Publication date: 1999-07-29
Also published as: AU2060899A; FR2773813B1; EP1049750A1; JP2002501105A; FR2773813A1; BR9907015A

Abstract

The invention concerns a composition for stripping coats for example of paints. Said composition comprises at least a carbocyclic ketone with five carbon atoms in the cycle.

Description

1

COMPOSITION FOR STRIPPING PAINTS.

The present invention relates to a composition for stripping coatings, for example based on paints.

The invention also relates to the process for stripping paints deposited on a substrate using said composition.

The first paint stripping compositions were based on methylene chloride and / or 1,1,1-trichloroethane (T.1.1.1.) (See for example US-A 2,507,983 and DE-A 2,524752 ).

Such compositions have the advantage of being effective and inexpensive. However, they can cause damage to the environment and more particularly to the ozone layer (Montreal protocol aimed at stopping the use of T.1.1.1 normally at the end of 1995).

Significant progress has been made by replacing these chlorinated solvents, either by lactams or lactones, the most common of which are N-methyl-2-pyrolidone or -butyrolactone (US-A 4 120810), or by a mixture alkyl diester of diacids which is a by-product of the industry for the production of monomers necessary for the preparation of polyamides (DE-3,438,399).

The above compositions are not always suitable for the stripping of coatings of different nature such as water-based paints, oil-based paints, lacquers, varnishes and plastic resins. It is known from US-A 2694658 to use dimethyl sulfoxide as a solvent for pickling paints. However, this type of solvent has the disadvantage of being very expensive and requires being used in large quantities.

According to EP-A 573 339, a new stripping composition has been proposed comprising an aprotic polar solvent and an ether comprising one or more methoxy groups and having well-defined characteristics such as a flash point greater than 0 ° C. and a lower molar volume. to 160.

There is therefore a need to supply new stripping compositions on the market.

Specifically, the present invention aims to provide a composition for the stripping of coatings including paints 2 characterized in that it comprises at least one carbocyclic ketone having 5 atoms in the ring.

By "carbocyclic ketone having 5 atoms" is meant any ketone compound having a saturated hydrocarbon ring of 5 carbon atoms and optionally bearing a substituent.

The ring can carry a substituent.

The number of substituents on the cycle is at most 4 but generally there is the presence of one or two substituents on the cycle.

The nature of the substituent can be very varied and not limiting. However, due to economic imperatives, the ketone compounds cannot be overly sophisticated and generally the substituents are alkyl groups having 1 to 4 carbon atoms, preferably a methyl group or a halogen atom, preferably a fluorine atom.

In the rest of the description of the invention, the term "cyclopentanone" means cyclopentanone or a substituted cyclopentanone.

As ketone which can be used in the compositions according to the invention, mention may be made of:

- cyclopentanone,

- 2-methylcyclopentanone, - 3-methylcyclopentanone,

- 2-chlorocyclopentanone,

- 2,2-dimethylcyclopentanone,

- 2,4-dimethylcyclopentanone,

- 2,5-dimethylcyclopentanone, - 3,4-dimethylcyclopentanone,

- 2,2,4-trimethylcyclopentanone.

Cyclopentanone is preferably used.

According to a preferred variant of the invention, the stripping compositions of the invention combine a ketone as defined by the invention and an aprotic polar solvent.

As examples of polar aprotic solvents, mention may be made of acetylacetone, acetonitrile, dimeethylsu oxide, dimethylformamide, N-methylmorpholine, N-methyl-2-pyrolidone and their mixtures. Another class of solvents which can be associated with cyclopentanone, is constituted by aliphatic, cycloaliphatic or aromatic ethers.

As preferred examples, one can mention: 3

- 1-tert-butoxy-2-methoxyethane,

- anisole,

- phenetole,

- ethylene glycoldimethyl ether, - 1,2-dimethoxybenzene,

- 1,3-dimethoxybenzene, 1,4-dimethoxybenzene,

- 2-methoxy-1, 3-dioxolane,

- diethylene glycoldimethyl ether, - 1,2,3-trimethoxybenzene.

As regards the polar aprotic solvent, anisole, phenetole, acetylacetone, acetonitrile, dimethylformamide, N-2-methylpyrolidone are preferably chosen.

The object of the present invention is to propose a composition allowing the stripping of paints comprising, by volume:

(1) - from 1 to 90% of a polar aprotic solvent,

(2) - from 1 to 90% of a carbocyclic ketone.

The preferred compositions of the invention therefore comprise at least, by volume: (1) - from 20 to 80% of an aprotic polar solvent, and more preferably from 20 to 50%, (2) - from 20 to 80% a carbocyclic ketone, and more preferably from 50 to 80%. Examples of compositions according to the invention are given below: (1) - from 1 to 90%, preferably from 20 to 80% and even more preferably from 20 to 50% of an aprotic polar solvent chosen from acetylacetone, acetonitrile, dimethylformamide, N-methyimorpholine, N-methyl-2-pyrolidone, 1-tert-butoxy-2-methoxyethane, anisole, phenetole, ethylene glycol dimethyl ether, 1,2 -dimethoxybenzene, 1,3-dimethoxybenzene, 1,4-dimethoxybenzene, 2-methoxy-1,3-dioxolane, diethylene glycoldimethyl ether, 1,2,3-trimethoxybenzene and their mixtures, (2) - from 1 to 90%, preferably from 20 to 80%, and even more preferably from 50 to 80% of cyclopentanone.

The preferred compositions according to the invention comprise: (1) - from 1 to 90%, preferably from 20 to 80% and even more preferably from 20 to 50% of a chosen aprotic polar solvent 4 among acetylacetone, acetonitrile, dimethylformamide, N-methyl-2-pyrolidone, anisole, phenetole and their mixtures, (2) - from 1 to 90%, preferably from 20 to 80% , and even more preferably from 50 to 80% of cyclopentanone.

The compositions according to the invention may also contain other conventional additives.

As examples of such additives, there may be mentioned, inter alia, a co-solvent, a surfactant, a thickener, an activator, a corrosion inhibitor, an evaporation retarder or any other additive insofar as it does not exist. not a chlorinated solvent.

The addition of a co-solvent generally makes it possible to increase the pickling performance of a composition by facilitating the dissolution of the plasticizers present in the paint. As examples of co-solvents, it is possible to use a liquid, aliphatic or aromatic and odorless hydrocarbon-based solvent having a flash point greater than 50 ° C., preferably greater than 70 ° C. so that this solvent is not classified in the flammable liquids.

Examples of such solvents derived from petroleum and with a high flash point, are in particular mineral spirits such as white spirit and naphthas.

As commercial products, it is possible to use in the compositions according to the invention, ISOPAR from Exxon, SOLTROL from Shell and HI-SOL solvents from Ashland, in particular SOLVESSO 100, 150 and 200.

However, the hydrocarbon derivatives being classified Xn (harmful), they are gradually replaced by solvents of the dialkyl ester type of an aliphatic diacid making it possible to avoid labeling Xn on the finished product.

Thus, it is preferred to use a C ₁ -C ₄ dialkyl ester of at least one C ₄ -C ₆ aliphatic diacid.

The mixture of diacid esters are esters derived essentially from adipic, glutaric and succinic acids, the alkyl groups of the ester part being especially chosen from methyl and ethyl groups, but may also be propyl, isopropyl, butyl, n-butyl and isobutyl.

The diacids C ₄ to Ce above are in fact the by-products of the preparation of adipic acid which is one of the main monomers of polyamides, and the dialkyl esters are obtained by esterification of this by-product which contains generally by weight from 15 to 30% of succinic acid, from 50 to 75% of glutaric acid and from 5 to 25% of adipic acid. Diacid esters are commercially available products. As commercial products, there may be mentioned more particularly Rhodiasolv RPDE® marketed by the company Rhône-Poulenc and "Du Pont Dibasic Esters®" marketed by the Company Du Pont de Nemours. As regards the quantity of co-solvent to be used, it is recommended to use from 10 to 100 volumes, preferably from 30 to 60 volumes of the co-solvent per 100 volumes of (1) and (2).

It is possible to add one or more surfactants to the stripping composition. These surfactants facilitate rinsing with water of the compositions on the substrate to be stripped and, in certain cases, of accelerating the stripping action.

Examples of anionic surfactants that may be mentioned are anionic surfactants of the alkali metal soap type (alkaline salts of C8-C24 fatty acids), alkali sulfonates (Cβ-C13 alkylbenzene sulfonates, C12 alkylsulfonates) C16), fatty alcohols in Cβ-Ciδ oxyethylenated and sulphated, alkylphenols in C8-C13 oxyethylenated and sulphated, alkali sulphosuccinates (alkyl sulphosuccinates in C12-C16) ...

As regards nonionic surfactants, there may be mentioned, inter alia, ethoxylated or ethoxy-propoxylated alkylphenols and ethoxylated or ethoxy-propoxylated fatty alcohols, ethoxylated or ethoxy-propoxylated triglycerides, ethoxylated or ethoxy-fatty acids propoxylated, ethoxylated or ethoxy-propoxylated sorbitan esters, ethoxylated or ethoxy-proproxylated amines, ethoxylated or ethoxy-propoxylated di (phenyl-ethyl) phenols, tri (1-ethyl phenyl) ethoxylated or ethoxylated phenols .

The number of oxyethylene (OE) and / or oxypropylene (OP) units of these nonionic surfactants usually varies from 2 to 100 depending on the HLB (hydrophilic / lipophilic balance) desired. Preferably, the number of OE and / or OP units is between 2 and 50.

The ethoxylated or ethoxy-propoxylated alkylphenols generally have 1 or 2 alkyl groups, linear or branched, having 4 to 12 carbon atoms, in particular octyl, nonyl or dodecyl.

By way of examples of preferred nonionic surfactants, mention may be made of ethoxylated nonylphenol with 2 to 9 ethylene oxide units.

The ethoxylated or ethoxy-propoxylated fatty alcohols generally have from 6 to 22 carbon atoms, the OE and OP units being excluded from these numbers, and are preferably ethoxylated.

The ethoxylated or ethoxy-propoxylated triglycerides can be triglycerides of plant or animal origin (such as lard, tallow, peanut oil, butter oil, cottonseed oil, oil flaxseed, oil olive, palm oil, grape seed oil, fish oil, soybean oil, castor oil, rapeseed oil, coconut oil, coconut oil), and are preferably ethoxylated.

The term "ethoxylated triglyceride" is used in the present invention to cover both the products obtained by ethoxylation of a triglyceride with ethylene oxide and those obtained by transesterification of a triglyceride with a polyethylene glycol.

The ethoxylated or ethoxy-propoxylated fatty acids are esters of fatty acids (such as for example oleic acid, stearic aid) and are preferably ethoxylated. The term "ethoxylated fatty acid" includes both the products obtained by ethoxylation of a fatty acid with ethylene oxide as well as those obtained by esterification of a fatty acid with a polyethylene glycol.

The ethoxylated or ethoxy-propoxylated sorbitan esters are cyclized sorbitol esters of fatty acids from C ₁₀ to C _2Q such as lauric acid, stearic acid or oleic acid, and are preferably ethoxylated.

Ethoxylated or ethoxy-proproxylated fatty amines generally have from 10 to 22 carbon atoms, the OE and OP units being excluded from these numbers, and are preferably ethoxylated.

The surfactant (s) may be used at a content which may for example be between 0.1 and 10%, preferably 0.5 and 5% by weight relative to the total weight of the composition.

It is desirable that the compositions of the invention contain thickening agents so that the composition can be applied to vertical surfaces. Conventional thickening agents can be used such as, for example, cellulose derivatives (ethylcellulose, hydroxypropycellulose), xanthan, guar, locust bean gums, alginates, polyacrylates, starches, modified starches and modified clays.

The thickening agents are preferably used at a content of between 0.5 and 10% by weight relative to the total weight of the composition, preferably between 1 and 3%.

In order to increase the speed of paint removal, it is possible to add an activator. It is a small polar molecule that will help break the adhesive bonds between the paint film and the substrate. As an example, mention may be made of the methylphosphoric ester or formic acid in the form neutralized with an amine, preferably triethanolamine (TEA). The activators are preferably used at a content of between 0.5 and 2% by weight relative to the total weight of the composition, preferably around 1%.

The stripping compositions can also contain, for example, corrosion inhibitors, preferably triethylammonium phosphate or sodium benzoate; evaporation retarders, for example paraffinic fats having a melting point between 46 and 57 ° C; abrasive particles chosen from aluminum oxide, silica, silicon carbide, tungsten carbide and silicon carbonitride.

The compositions according to the invention allow the paint stripping.

In this text, the term "paintings" is used generically. It designates any coating of a polymeric nature deposited on a support and more particularly, paints strictly speaking, varnishes and plastic resins.

The compositions are more particularly applicable in the case of glycerophthalic, polyurethane, acrylic, alkyd-urethane, acrylic-polyurethane and epoxy paints.

The paints are preferably paints used in the household and industrial sector, in particular the building industry.

The substrates to be cleaned or pickled can be very varied in nature.

The most common are wood; metals and their alloys such as steel, stainless steel, aluminum, copper, iron; plastics and mineral glasses.

Advantageously, compositions comprising cyclopentanone and / or anisole and / or phenetole and / or DMF and / or NMP and / or acetylacetone and / or acetonitrile are used to strip paints preferably of polyester or polyurethane.

The invention also relates to a process for stripping paints on substrates, characterized in that said paints are brought into contact with a composition according to the present invention.

The compositions according to the invention can be prepared at ambient temperature (generally 5 to 25 ° C.), by simple mixing of the various components, using an agitator or any other suitable device. 8

The stripping process is carried out by bringing the object or surface to be stripped into contact with the composition according to the present invention.

This contacting is continued until the paint swells, blisters and peels off.

Contacting the object or surface to be stripped with the composition according to the present invention can be done by various means.

Among these means, we can mention immersion, spraying, coating with a brush. The contacting is carried out at a temperature between 5 and

25 ° C, i.e. at room temperature.

The contact time is between 15 and 120 minutes.

The use of cyclopentanone alone is the most effective solvent vis-à-vis the two polyester and polyurethane paints.

Cyclopentanone is advantageously combined with anisole or phenetole.

The composition of the invention is free from chlorinated solvents and is stable on storage for at least one year.

Examples of the invention are given below. In the examples, the percentages of the constituents of the stripping composition are expressed by volume unless otherwise stated.

These examples are given by way of illustration and without limitation.

Examples

We specify beforehand the operating protocol which will be followed in the examples.

4 drops of formulation are deposited on the paint plates and the time required for swelling or "blistering" of the paint is noted using a chronometer without any mechanical aid. This time is notified in minutes or in hours if the pickling time is more than 60 min.

The formulations are tested on paint plates manufactured by the company ETALON. Polyurethane paint Ref. (90x190 ZESPHOS + PU) batch number 7163-7

White polyester paint Ref. (90x190 ZESPHOS + White / 389) batch number 7162-7

The results obtained are as follows: Time required for paint to swell

Solvent composition containing 1% by weight Paint Formic acid paint and 3% TEA by weight polyurethane polyester

100% DMSO no action no action

100% NMP no action 40 min

100% DMF no action 1 h 30 min

100% anisole 30 min 1h 15 min

100% phenetole 1h15 min no action

100% acetone no action no action

100% acetylacetone 1 h 40 min 1 30 min

100% cyclopentanone 16 min 29 min

75% cyclopentanone 25% phenetole 29 min 38 min

75% cyclopentanone 25% anisole 16 min 25 min

50% cyclopentanone 50% NMP 33 min 25 min

50% cyclopentanone 50% DMF 1 h 45 min 16 min

50% cyclopentanone 50% acetonitrile 32 min 17 min

50% cyclopentanone 50% acetylacetone 16 min 28 min

Cyclopentanone alone is the most effective solvent for both polyester and polyurethane paints.

The stripping power of cyclopentanone can be improved by combining it with solvents such as anisole, NMP, DMF, acetonitrile and acetylacetone, in particular with respect to polyurethane paint.

Claims

10 CLAIMS 1 - Composition allowing the stripping of coatings, in particular based on paints, characterized in that it comprises a carbocyclic ketone having 5 atoms in the cycle. 2 - Composition according to claim 1 characterized in that the carbocyclic ketone is cyclopentanone or a cyclopentanone whose ring carries alkyl groups having from 1 to 4 carbon atoms, preferably, a methyl group or a halogen atom, preferably, a fluorine atom. 3 - Composition according to one of claims 1 and 2 characterized in that it also comprises an aprotic polar solvent. 4 - Composition according to one of claims 1 to 3 characterized in that the aprotic polar solvent is acetylacetone, acetonitrile, dimethyl sulfoxide, dimethylformamide, N-methylmorpholine, N-methyl-2-pyrolidone and their mixtures. 5 - Composition according to one of claims 1 to 4 characterized in that the aprotic polar solvent is an ether, preferably 1-tert-butoxy-2-methoxyethane, anisole, phenetole, ethylene glycol dimethyl ether, 1,2-dimethoxybenzene, 1,3-dimethoxybenzene, 1,4-dimethoxybenzene, 2-methoxy-1,3-dioxolane, diethyleneglycoldimethylether, 1,2,3-trimethoxybenzene. 6 - Composition according to one of claims 1 to 5 characterized in that it comprises by volume: (1) - from 1 to 90%, preferably from 20 to 80% of an aprotic polar solvent, and again more preferably from 20 to 50%, (2) - from 1 to 90%, preferably from 20 to 80% of a carbocyclic ketone, and even more preferably from 50 to 80%. 7 - Composition according to one of claims 1 to 6 characterized in that it comprises by volume: (1) - from 1 to 90%, preferably from 20 to 80% and even more preferably from 20 to 50% of a polar aprotic solvent chosen from acetylacetone, acetonitrile, dimethylformamide, N-11 methylmorpholine, N-methyl-2-pyrolidone, 1-tert-butoxy-2-methoxyethane, anisole, phenetole, ethyleneglycoldimethylether, 1,2-dimethoxybenzene, 1,3-dimethoxybenzene, 1,4-dimethoxybenzene, 2-methoxy-1,3-dioxolane, diethyleneglycoldimethylether, 1,2,3-trimethoxybenzene and their mixtures, (2) - from 1 to 90%, preferably from 20 to 80%, and even more preferably from 50 to 80% of cyclopentanone. 8 - Composition according to one of claims 1 to 7 characterized in that it comprises by volume:

(1) - from 1 to 90%, preferably from 20 to 80% and even more preferably from 20 to 50% of an aprotic polar solvent chosen from acetylacetone, acetonitrile, dimethylformamide, N-methyl -2-pyrolidone, anisole, phenetole and their mixtures,

(2) - from 1 to 90%, preferably from 20 to 80%, and even more preferably from 50 to 80% of the cyclopentanone.

9 - Composition according to one of claims 1 to 8 characterized in that it comprises a co-solvent, a surfactant, a thickener, an activator, a corrosion inhibitor, an evaporation retarder or any other additive .

10 - Composition according to claim 9 characterized in that the co-solvent is a C ₁ -C ₄ dialkyl ester of at least one C4-C6 aliphatic diacid.

11 - Composition according to one of claims 1 to 10 for stripping paints, varnishes and plastic resins.

12 - Composition according to one of claims 1 to 11 for stripping glycerophthalic, polyurethane, acrylic, alkyd-urethane, acrylic-polyurethane and epoxy paints.

13 - Composition according to one of claims 1 to 12 for stripping coatings deposited on substrates: wood, metals and alloys such as steel, stainless steel, aluminum, copper, iron; plastic materials and mineral glasses. 12

14 - Process for preparing the compositions described in one of claims 1 to 10 characterized in that a simple mixing of the different components is carried out, using a stirrer or any other suitable device.

15 - Process for stripping a coating deposited on a substrate characterized in that the coating is brought into contact with the composition described in one of claims 1 to 10.

16 - Method according to claim 15 characterized in that the contacting is continued until the paint swells, forms blisters and peels off.

17 - Method according to one of claims 15 and 16 characterized in that the contacting is carried out by any means, preferably by immersion, sprinkling, coating using a brush.

18 - Method according to one of claims 15 to 17 characterized in that the contacting is carried out at room temperature.