CA1320675C - Paint stripping composition containing five membered ring lactone - Google Patents

Abstract

IMPROVED PAINT STRIPPING

ABSTRACT OF THE DISCLOSURE

A paint stripping composition used in a process where it is applied to a substrate coated with fully or partially cured paint, having particular utility for use in stripping paint with other utilities, e.g. stripping organic polymer coatings also contemplated, and a method of employing same is described.

Description

1IMPROVED PAINT ST~IPPING

4The present invention relates to a paint stripping composition used in a process where it is applied to a 6 substrate coated with fully or partially cured paint. The 7 composition of the present invention has particular 8 utility for use in stripping paint and will be described 9 in connection with such utility, although other utilities, for example, stripping brganic polymer coatings, also are 11 contemplated. The present invention is also directed to a 12 method of employing the strippin~ composition.
13 BRIEF DESCRIPTION OF T~E BACKGROUND ART
14 A paint or varnish remover should ideally remove all traces of the coating quickly and with a minimum of labor, 16 and it should leave the substrate unharmed and suitable 17 for reprocessing or refinishing. A number of design 18 criteria have been identified for a modern stripper:
19 stripping ability, lack of corrosiveness to substrates~
freedom from galvanic attack at the juncture of dissimilar 21 materialsl freedom from noxious and toxic chemicaIs, good 22 shelf life, high viscosity, where needed, sealable 23 internally or with a water cap to prevent rapid 24 evaporation, and ability to Ieave a readily recoatable surface. See The Encyclopedia of Chemical Technology, 26 Third Edition, Volume 16, 762-768 tl981).
27 Methylene chloride`paint strippers have long been the 28 industry standard for paint stripper performance. It has 29 been established that methylene chloride is effective for quickly softening most types of paints. It has been 31 suggested that the effectiveness of methylene chloride 32 results from its smaller molecular size. Its low 33 molecular weight enables it to penetrate rapidly into a 34 coating, and its intermediate solvency enables the coating not to be dissolved so that redisposition on the substrate 36 is avoided. Methylene chloride removers have also been 1 3~0675 1 modified to increase stripping power for special purposes.

2 These modifying chemicals include amines, alkalies and 3 organic acids. See U.S. Patent 3,538,007 to Cooper et.

4 al. Other reported uses of methylene chloride include solvent degreasing, plastics processing, blowing agent in 6 foams, solvent extraction, a solvent for cellulose 7 acetate, and as an aerosol propellant.
8 The safe use of methylene chloride has been quPstioned 9 by Federal agencies including the Food and Drug Administration (FDA). As a chlorinated solvent, methylene 11 c~loride has now been closely regulated for environmental 12 protection. Recently, it was discovered that methylene 13 chloride can cause tumors in rats and mice. The LD50 14 orally in rats (young adults) has been found to be 1.6ml/kg. Furthermore, the threshold limiting value (TLV) 16 has been set at 100 ppm in air. See Kimura, et. al., 17 Toxicol. Appl. Pharmacol. 19, 699 (1971). Since these 18 discoveries, the wide use of the solvent by industry and 19 consumers has come under close scrutiny by federal regulatory agencies. See, U.S. Patent 4,749,510 to 21 Nelson. Accordingly, it is now highly desirable to avoid 22 the use of methylene chloride in paint stripping 23 formulations.
24 The search for an alternative product to methylene chloride has focused attention on pyrrolidone type 26 compounds, more specifically, N-methyl-2-pyrrolidone 27 (NMP). NMP~is less toxic than many competitive aprotic 28 solvents and does not appear to be a sensitizing agent.
29 NMP, a dipolar aprotic solvent, has a high dielectric constant and cannot donate protons for hydrogen bonding.
31 Consequently, many of its applications involve its strong 32 and frequently selective solvating power. NMP is 33 commercially available (e.g., from BASF Wyandotte or GAF) 34 and used industrially as a processing aid for polymeric resins, in petroleum processing (e.g., the extraction of 36 aromatics from lube oil), for the production of electronic * Trade mark ~.

1 circuitry, and as a general industrial cleaning 2 ingredient. NMP is a colorless liquid with a mild amine 3 odor, is miscible with water as well as various organic 4 solvents. See the ~ncyclopedia of Chemical Technology, Third Edition, Vol. 19, 514-520 (1981).
6 Although NMP was recognized as an early candidate for 7 replacing chlorinated solvent type paint strippers, it was 8 soon discovered that a formulation based entirely on NMP
9 had a number of disadvantages.
For example, NMP has low viscosity and low adhesive 11 properties which work against its efficiency to remove 12 dried coats of paint on a vertical surface. In U.S.
13 Patent 4,764,222 to Colegrove, a NMP composition is 14 reported where a viscosifying agent (rhamsan gum) is added to the NMP to improve the ability of the composition to 16 cling to a painted surface when inclined in a vertical 17 position. An effort to optimi~e or target the paint 18 removing efficiency and water solubility of NMP,~while at 19 the same time controlling and minimizing any potential toxicity and volatility, has led to a variety of specific 21 formulations combining NMP with other organic and 22 inorganic compounds. In U.S. Patent 4,276,186 to Bakos 23 et. al., cleaning compositions containing at least 50% by 24 weight of NMP and at least about 5% by weight of a water miscible alkanolamine and about 0-35% by weight of a 26 hydrocarbon solvent were described as especially suitable 27 for removing solder flux from a ceramic substrate. In 28 U.S. Patent 4,664,721 to Valasek, non-aqueous compositions 2~ of NMP, butyl cellosolve and cyclohexanone and a surfactant are disclosed which degraded or solubilized 31 broad classes of printing ink residues on printing 32 screens. In U.S. Patent 4,812,255 to Suwala, an aliphatic 33 organic acid, an alkylene glycol ether and NMP are 34 combined and reported effective as an overall composition for paint removal. In U.S. Patent 4,732,695 to Francisco, 36 a paint stripper and coatings remover composition 1 consisted of three essential components: NMP, a mixture 2 of aromatic hydrocarbons and benzyl alcohol. Finally, in 3 U.S. Patent 4,749,510 to Nelson, there is described a 4 paint stripping composition comprising about 20-90% by weight NMP, 30-70% by weight aromatic hydrocarbon solve,nt, 6 and about 1-15% by weight of either formic, oxalic, 7 acetic, citric, gluconic or glutamic acid. According to 8 another aspect of Nelson, organic amines such as diethanol 9 amine could replace the various organic acids.
The combination of NMP with a variety of operative 11 organic compounds represents what has been a long-standing 12 effort to maximize the stripping ability of this 13 alternative paint and coatings remover. While some of the 14 presently disclosed paint strippers have relied upon lS formulations and proportions of active organic compounds 16 in combination with NMP, none have recognized the novel 17 and enhanced solvating power of the present invention 18 which utilizes components that are commercially widely 19 available, are less expensive than NMP, remove certain paints, coatings, inks or crayon at the same or better 21 rate than NMP alone, can replace the majority of NMP in a 22 given formulation, and are biodegradable, non-flammable 23 and non-toxic.
24 It is accordingly an object of the present invention to provide an effective non-methylene chloride paint 26 stripper composition that can be readily mixed and 27 formulated to produce a stripper with the aforementioned 28 solvating capability.
29 Another object is the provision of a stripper of the above type which can be applied by any conventional `31 method, including wetting, wiping, spraying, brushing, 32 dipping, troweling or otherwise.
33 Yet another object is to provide an effective 34 composition with the aforementioned properties for cleaning urethane, polyester and epoxy compounds off of 1 tools, molds, etc., particularly before the cure is 2 complete.
3 A still Eurther object is to provide a stripper 4 composition of the above type which emulsifies with and can be completely removed by water.
6 SUMMARY OF T~E INVENTION
7 The above and other objects and advantages are 8 achieved by a stripper composition which comprises 9 essentially of a mixture of the two following essential components: (1) a five-membered ring lactone, and (2) an 11 oxygenated aliphatic solvent.
12 The composition preferably also contains ce~tain other 13 components including a thickener, preferably a cellulose 14 ether derivative such as hydroxy propyl cellulose, a conventional surfactant, preferably tridecylalcohol-16 6-mole-ethoxylate, corrosion inhibitors, dyes and 17 fragrances. All of these additional components are 18 employed in effective amounts, particularly in certain 19 ranges of proportions, as set forth in greater detail below.
21 Thè inventive composition is particularly effective 22 for stripping and cleaning of paints, coatings, inks and 23 crayon as well as cleaning some urethane, polyester and 24 epoxy compounds off of tools, molds, etc., particularly before the cure is complete. The paint stripper 26 composition of the invention is readily formulated from ~7 commercially available solvents and applied by any ~ conventional method, including wetting, wiping, spraying, 29 brushing, dipping, troweling or otherwise. The paint or coating is removed easily without any substantial waiting 31 or soaking, followed by water rinsing to clean the removed 3~ paint. The paint/coatings stripper hereof readily 33 emulsifies with water and is removed completely by water.
34 As formulated the stripper composition of the invention is essentially non-flammable, non~carcinogenic, and non-36 toxic.

2 One of the two essential components in the paint and 3 coatings stripper formulation of the present invention is 4 a five-membered ring lactone. Preferred in this group is N-methyl-2-pyrrolidone (NMP), as well as other hydrocarbon 6 2-pyrrolidones, for example, N-ethyl-2-pyrrolidone, N-7 isopropyl-2-pyrrolidone, N-cyclohexyl-2-pyrrolidone, 8 2-hydroxyethyl-2-pyrrolidone, N-dimethylaminopropyl-9 2-pyrrolidone, vinyl-pyrrolidone, 2-pyrrolidone and mixtures thereof. Particularly preferred is NMP which is 11 a cyclic amide having a flashpoint (open-cup) of 95C.
12 The chemical formula for NMP is C5HgNO.
13 The seeond essential component of the present 14 invention is an oxygenated aliphatic solvent. Preferred are esters of propionic acid, in particular the methyl, 16 ethyl, propyl, isopropyl, butyl, isobutyl, 3-methylbutyl, 17 pentyl, hexyl, heptyl, octyl esters of propionic acid, and 18 mixtures of the foregoing. Particularly preferred is 19 ethyl-3-ethoxypropionate which when combined with NMP
provides the two primary constituents in the 21 paintjcoatings stripper composition of the present 22 invention. Amongst other oxygenated solvents useful in 23 the present invention which may be used in mixture with or 24 as a substitution for the aforesaid esters of propionie acid are mentioned aliphatic alcohols such as butyl 26 alcohol, amyl alcohol, hexyl alcohol, heptyl alcohol, 27 furfuryl alcohol, tetrahydrofurfuryl alcohol, 28 2-butoxy ethanol; 2 or 3 carbon atom; alkylene glycol 29 ethers such as propylene glycol mono-t-butyl ether, dipropylene glycol mo~o~methyl ether, and dipropylene 31 gylcol mono-n-butyl ether; 6 to 8 carbon atom; aliphatic 32 dibasic esters such as dimethyl succinate, dimethyl 33 glutarate and dimethyl adipate; and aliphatic ketones such 34 as diisobutyl ketone. While such other solvents provide a formulation which is relatively non-toxic, the speed of 36 paint removal is not as great as when using ethyl-37 3-ethoxypropionate. It has been observed that up to 50%

1 of the ethyl-3-ethoxypropionate may be replaced by 2 2-butoxyethanol with little or no apparent sacrifice in 3 paint removal performance; however, 2-butoxyethanol is not 4 preferred since it has been suspected o~ having toxic properties.
6 The amount of each of the two essential components in 7 the final composition may vary within a certain range.
8 What is important, however, is that each be present in an 9 amount sufficient to provide the composition with effectiveness for stripping and cleaning of paints, 11 coatings, inks and crayon as well as cleaning urethane, 12 polyester and epoxy compounds off of tools, molds, etc., 13 particularly before the cure is complete. Therefore, in 14 accordance with the broad principles of this invention, the combin`ation of the two essential components from the 16 above mentioned classes is achieved by a consideration of 17 the solvating capacities o-f the respective components, 18 individually and in combination, in order to obtain the 19 most desired biodegradable, least flammable and~highest threshold limiting values to meet or exceed health and 21 safety standards. Typicallyj the composition may contain 22 from about 10-90% of the five-membered ring lactone, 23 preferably from about 20-40%, and in the most preferred 24 embodiment about 30-35% by weight of the paint stripper composition. The other essential component, i.e., the 26 oxygenated aliphatic solventj may be present in the 27 composition from about 10-90% preferably from about 55-75%, and in the most preferred embodiment about 65-70%
29 by weight of the paint stripper composition.
Surface active agents also may be utilized in the 31 composition. These compounds tend to reduce the surface 32 tension when dissolved in water or water solutions, or 33 reduce interfacial tension between two liquids, or between 34 a liquid and a solid. There~ore, in the context of the paint stripping formulations of the present invention, 1 which is water soluble, the surface active agents serve to 2 make the various stripping formulations amenable to water 3 flushing from the treated surface. That is, when the 4 assorted fcrmulations of this invention are applied to non-water soluble paints and coatings, along with 6 surface-active agents, such agents are further believed to 7 effect an emulsion of the organic residues that have been 8 removed from the various substrates on contact with water.
9 Such emulsions can then be rinsed from the treated surface with water.
11 Surface-active agents may be of four types, nonionic, 12 anionic, cationic or amphoteric. They are selected for 13 solubility in the stripping formulation, low toxicity, the 14 ability to form a useful emulsion of the formula with lS water, and biodegradability. Normally, if surface-active 16 agents are included in the formulationj they are included 17 in the amount from about 1 to 8 weight percent, and 18 preferably from about 3 to 6 weight percent. A preferred 19 embodiment of the present invention includes an oil soluble nonionic surfactant, the 6-mole ethoxylate of 21 tridecyl alcohol which is available from GAF under the 22 tradename ~mulphogene 610* and from Stepan under the 23 tradename Makon TD-6*
24 Corrosion inhibitors may also be included in the inventi~e formulation. Such corrosion inhibitors are 26 conventional. Typical corrosion inhibitors include mono-, 27 di-, and triethanol amines as well as many solvent soluble 28 commercial preparations. Other acceptable amines include 29 diethylethanolamine, diisopropylamine, ethylamine, ethylenediamine, isopropylamine, monoisopropanolamine, 31 morpholine, triethylenetetramine, and triisopropynolamine.
32 ~ixtures of such alkanolamines can be employed when 33 desired.
34 For stripping vertical surfaces the addition of a thickener or gelling agent is highly desirable. The 36 preferred thickeners or gelling agents are cellulose * Trade mark .~

1 derivatives having the property of both water and organic 2 solvent solubility. Cellulose derivatives o this type 3 which are of par-ticular interest are those ether 4 derivatives containing etherifying groups selected from hydroxyalkyl groups and groups derived therefrom, such 6 etherifying groups containing preferably up to about 5 or 7 6 carbon atoms. The gelling agent also may comprise 8 cellulose ether derivatives which, in addition to 9 etherifying groups selected from hydroxyalkyl groups and groups derived therefrom, contain other types of 11 etherifying groups, especially small alkyl groups of, for 12 example, one or two carbon atoms. However, such 13 etherifying groups generally confer properties upon the 14 cellulose derivative which are less acceptable for the prPsent purpose, and the gelling agent is therefore 16 conveniently substantially restricted to cellulose 17 derivatives containing the etherifying groups selected 18 from the hydroxyalkyl groups and groups derived therefrom.
19 Etherifying groups consisting of or derived from hydroxyalkyl groups containing up to S carbon atoms, 21 particularly, 2, 3 or 4 carbon atoms, are of especial 22 value. The hydroxypropyl celluloses, for example, have 23 been found to be of particular value in imparting quite 24 adequate thickening properties in their own right without the need for any other agents for these purposes. The 26 hydroxypropyl group in these cellulose derivatives may be 27 derived from either isopropanol or n-propanol and a number 28 of variations are possible. For any etherification of 29 cellulose, not all of the free hydroxy groups on the cellulose need necessarily be substituted. Consequently 31 any free hydroxy groups, and the hydroxypropyl group 32 itself, may be further substituted by treatment with other 33 aliphatic alcohols. The hydroxypropyl celluloses employed 34 in formulations according to the present invention have molecular weights in the range o~ 50,000 to about 36 1,000,000, preferably from about 800,000 to 1,000,000.

l Since the molecular weight of these described thickeners 2 is directly proportional to their ability to alter the 3 viscosity of a given formulation, the concentrations that 4 are preferred for a desired viscosifying effect will vary depending on the molecular weight selected. The 6 proportions of thickener in the formulations can be in the 7 range of 0.25% to 10%, or even 15%, 18% ox 20% by weight.
8 Thus, for example, the usual proportion of thickening 9 agent of from about 0.25% or 0.5% upwards is suitable for high molecular weight materials and of from about 3%
ll upwards being suitable for lower molecular weight 12 materials. For high molecular weight materials, for 13 example molecular weights of 800,000 to 1,000,000 a 14 proportion of above 1.5% is preferably avoided as it leads to a viscosifying effect of too large a magnitude. With 16 low molecular weight materials, larger proportions may be 17 used before such a position is reached and, if the 18 molecular weight is low enough, amounts of up to 10% or 19 even 20% or more may be used. It will be appreciated, however, that the use of a smaller amount of material of 21 high molecular weight is generally to be preferred.
22 Dyes and fragrances can be selected according to the 23 needs of product identification as well as aesthetics.
24 The appropriate dye or fragrance should be chemically ~S stable in the formulations, as well as having little or no 26 effect on the ability of the given formulation to effect 27 removal of the paint or coating from the substrate.
28 Furthermore, the dye or fragrance should have little to no 29 effect on the ability of the surface-active agent to create an emulsion so that rinsability with water is 31 maintained. Preferably, only a small amount of such a dye 32 ox fragrance will be employed, from about 0.001% to 0.1%
33 by weight of the entire formulation. Typical of such dyes 34 are are Pylaklor*L~-19llA Orange which is available from Pylam. Any commercially available fragrance may be 36 employed.
* Trade mark ,f `~
~t 2 The following examples, illustrative of the present 3 invention, involve: mixing of the constituents together 4 by blending with a mechanical mixer in a tank or other similar vessel. The formulation of this invention is 6 prepared by first vigorously mixing the oxygenated 7 aliphatic hydrocarbon solvent as the thickener is sifted 8 over the surface of the solvent which then forms a fine 9 uniform miscible mixture forming a gel. The thickener is added extremely slowly to permit the thickener to dissolve 11 without forming a precipitate or large agglomeration. The 12 extremely slow rate of addition of the thickener to the 13 mixture is required due to the relative incompatibility of 14 some of~the cellulose ether derivatives. If some of the cellulose ethers are added too quickly, a precip~itate or 16 agglomeration will form and the cellulose ether will not 17 function as a thickening agent for the paint/coatings 18 stripper.
19 Next, the corrosion inhibitors, dyes, fragrances and lactone are added to the oxygenated alphatic solvent and 21 cellulose ether, followed by the appropriate surface-22 active agent or mixture of surface-active agents.
23 The resulting formulation of the invention i9 used, 24 preferably undiluted for removing paint or coatings from a substrate. The formulation may be applied to the paint or 26 coated sur~ace by spraying, brushing, dipping, troweling, 27 or otherwise. The paint or coating on the surface is then 28 softened by the reaction with lactone and the oxygenated 29 aliphatic solvent and is held in suspension on the surface by the thickener, if present. After the paint or coating 31 is softened, the stripper and loosened paint may be rinsed 32 from the surface with water or manually scraped or sanded 33 from the substrate. The paint stripper normally requires 34 1 to 30 minutes to soften the paint on the substrate, depending on the type of paint.

2 Eollowing the procedure set forth above, the following 3 formulation was prepared:

Constituent _ % by Wei~ht~~
7 N-methyl-2-pyrrolidone 8 (NMP) 29.9 9 Rthyl-3-ethoxypropionate 65.0 6-mole ethoxylate of 11 tridecyl alcohol 5.0 12 Fragrance 0.1 13 Dye (Pylaklor LX-19llA
14 Orange) 0.001 The resultant paint stripper removed paint as rapidly 16 as NMP does alone and is significantly less expensive than 17 NMP. The time required to completely strip cured and 18 partially cured paint was about 1 - 5 minutes, depending 19 on t`he type of paint, and only a single application was requlred. The paint on the surface was degraded and 21 lifted off the substrate. Furthermore, it also removed 22 lipstick and crayon much faster than NMP which makes this 23 formula highly desirable for removing~graffitl when the 24 composition of the graffiti is unknown. The composition is highly biodegradable as demonstrated by the following 26 data:
~7 Chemical Oxygen Demand = 1.71 kg/kg 28 Concentration Tested 2mg/1. Smg/l.
~9 lOmg/l.

31 Biological 2 32 Demand (kg/kg/%) 34 Day 5 0.550/32.2% 0.610/35.9%
0.720/42.1%

1 Day 10 0.700/40.9% 0-740/43~3%
2 Septic 4 Day 15 0.950/55.6% 1.00/58.5%
Septic 7 Day 20 1.20/70.0% Septic 8 Septic The above tests were run by an independent laboratory 11 using an unacclimated municipal seed. The fact that 12 higher concentrations biodegraded faster and went septic 13 indicates that the inventive formulations have no toxicity 14 to treatment plant organisms. ~The % biodegradation is the lS BOD/COD multiplied by 100.

18 Following the procedure set forth above, the following 19 formulation was prepared: `~
2221 ~ Constituent % b~ Weight_ 24 Ethyl-3-ethoxypropionate 64 0 6-mole ethoxylate of 26 tridecyl alcohol 5.0 27 High Viscosity hydroxy-28 propyl cellulose 1.0 29 Fragrance 0.1 Dye (Pylaklor LX-19llA
31 Orange) 0.001 33 This example produces a high viscosity composition 34 which is highly effective for stripping vertical surfaces.
More particularly, water emulsions prepared with this 36 formula are more stable than those made with Example 1.

1 E~MPLE 3 2 Following the procedure set forth above, the following 3 formulation was prepared:

S Constituent ~-by weight 8 Ethyl-3-ethoxypropionate 70.0 Results: The formula-tion of Example 3 removed paint 11 equally as fast as the formulation of Example 1, and has 12 the advantage that it leaves no residue on air dr~ing, and 13 thus may advantageously be employed in the electronics 14 industry~ On the other hand, the formulation of Example will not adhere.
16 It is apparent that there has been provided in 17 accordance with the invention a paint stripper formulation 18 and a method of making and using the same. It will be 19 readily appreciated that the composition and method of the present invention overcome the disadvantages associated 21 with the prior art methylene chloride-based paint~
22 strippers.
23 The composition has a long work life which typically 24 permits complete removal from the substrate with a single appli`cation regardless of the thickness of the paint 26 accumulation. In most instances, since the stripper can 27 be left on until all the paint is loosened. Indeed, many 28 coatings will totally dissolve if soaked. This is a 29 s~ignificant advantage of the present invention as compared to methylene chloride paint strippers.
31 The paints upon which the paint stripper of the 32 present invention is effective include those 33 conventionally used as automotive touch-up paints, metal 34 enamels, lacquers, varnishes, polymer paints and others used in industrial processes and also general purpose 36 household paints and surface coatings. In addition, the 37 stripping formulations of this invention can remove many 38 of the dyes and pigments associated with lipstick and 1 32~675 1 s 1 crayon formulations which makes this formulation highly 2 desirable for removing graffiti where the composition of 3 the graffiti is unknown. The stripping composition of the 4 present invention also can be applied to reactive-vehicle or solvent borne coatings, and has also proven effective 6 for cleaning urethane, polyester and epoxy compounds off 7 of tools, molds, etc., particularly if applied before the 8 cure is complete. The composition also may be emulsified 9 with water and remain effective on many latex coatings.
Emulsions in the range of 70 parts to 30 parts of water to 11 30 parts of the inventive formulation to 70 parts of 12 water, are particularly useful. While the invention has 13 been described in conjunction with several specific 14 embodiments, it is evident that many alternatives, modifications, and variations of the invention will be 16 apparent in light of the foregoing description.
17 Accordingly, it is intended to embrace all such 18 alternatives, modifications, and variations as fall within 19 the spirit and broad scope of the appended clalms.

Claims (6)

1. A non-toxic, biodegradable and ambient temperature non-volatile liquid paint stripping composition, wherein the active ingredient consists essentially of the combination of:
(a) at least 30-90% by weight of a five membered ring lactam;
(b) at least 10-70% by weight of an oxygenated aliphatic solvent selected from the group consisting of the methyl, ethyl, propyl, isopropyl, butyl, isobutyl, pentyl, hexyl, heptyl and octyl esters of 3-ethoxypropionic acid;
(c) about 0-10% by weight of a viscosifying agent selected from the group consisting of cellulose ether thickeners containing an etherifying group selected from hydroxyalkyl groups and groups derived therefrom, such etherifying groups containing 5 or 6 carbon atoms;
(d) about 0-5% by weight of a nonionic, anionic, cationic or amophoteric surface active agent; and (e) about 0-1% by weight of a dye.

2. The composition of claim 1, wherein said five membered ring lactam comprises a lactam selected from the group consisting of N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, 2-hydroxy-ethyl-2-pyrrolidone, N-dimethylaminopropyl-2-pyrrolidone, vinyl-pyrrolidone, 2-pyrrolidone and mixtures thereof.

3. The composition of claim 1 wherein said lactam is N-methyl-2-pyrrolidone and is present in an amount of at least 30-40-% by weight.

4. The composition of claim 1, wherein said oxygenated solvent comprises ethyl-3-ethoxypropionate and is present in an amount from about 55-75% by weight.

5. The composition of claim 1, wherein said oxygenated aliphatic solvent comprises ethyl-3-ethoxypropionate and is present in an amount of at least 65% by weight.

6. A method of stripping paint from a substrate surface which comprises the steps of:
(a) treating at room temperature the substrate surface with the composition of claim 1;
(b) allowing the composition to dwell on the surface for a sufficient period of time to degrade the paint; and (c) removing the degraded paint by mechanical means or with pressurized stream of water.