US2398242A - Paint and varnish remover - Google Patents

Description

pm-m) s'rArss- PATENT; osslcs ram'r AND vanmsn ltnmo'vnn" John D. Morgan, South' orange, and; Russell l Lowe, East -range, N. 1., assirnorsto Cities Service Oil Company, New ration of Pennsylvania" 7 L Application October 10, 1944, Serial No. 558,082 I i No Drawing.

York, N.Y. a corpoinvention relates togimprovements inv paint and varnish removing compositions, and is a continuation-in-part'o: our pending application Serial No. 435,862,'iiied March 23,1942.

, Many oi the commonly used removing compounds are most effective in lilting paint and lacquers irom their supportingsuriaces only when applied in a heated state. It appears that the heat serves both to speed the penetration oi the solvent through the protective coating, material, as well as to render it more eflective in destroying the bond between the coating and its supporting I. surface. It is readily evident, however, that the heating of these volatile materials results. in great wastage. In order to overcome this diiilculty, it

A is more or less common prac tice'to immerse articles in a bath of the heated solvent,and to limit. evaporation losses by the use oi vapor recovery It is readily evident that the-hot dipping 'process is ,not' practicable for the stripping ,of paint from articles of any considerable It is hardly ieasible, tor example, to nmv i dipping tanks and handling equipment; or? .suflicient capacity to allow tor the treatmentor'icompiete aircrait,- or even. of its major sub-assemblies,

In of this kindit has sometimes been the practice to brush a hot remover solution overthei paintedsuriace, and by repeated operations to maintain a ilim oi-the remover on the ior a long enoughtime to allow it to hit the paint. a

This operation is time consuming,- wasteful, and

not effective. The thin him "oi, remover evaporates so rapidly that itdoes not have. time to penetrate the protective coating, and theiact' that the solution is hot increases this efl'ect. In addition, these light-bodled solvents run oil of vertical or sloping surfaces almost as last as they I can be applied, so that a very large part oi the out that thehot process is utterly. impractical at v in the 'remotest parts of the --'globe.

} The principal object of the invention is to provide a paint and varnish remover which acts 'eil'ectively-f'at normal atmospheric temperatures to penetrate protective coatings of paint and lacquer, andto loosen them from their supporting 1 surfaces, and which is of such a nature that it 10 may readily be applied with the simplest of equipment that may be found almost anywhere. It is a further and more specific object of the invention to provide a paint removing composition having the nature of a paste which is salt l5 enough toallow it to be spread readily over a suriace with a putty knife, or any other convenient tool, and which is still and sticky enough toadhere to a painted suriace,'even when solvent. ingredients may remain in contact with the paint for along enough period of time to penstrata and loosen it from the underlying part.-

Itisaiurther objector the invention to provide a paint and varnish remover composition oia Q pasty natureinwhich the active ingredientsare not corrosive to ordinary metals and other materials-of construction and whichmay therefore be retai ed'on-the surfaces of articles from which pain is: to be removed forrelatively long periods or time without giving rise to anydanger that the underlying parts will becorroded or damaged. This is particularly important in a remover which isito 'be used for stripping lac uer from aircraft parts which are most frequen y made of alumi humor aluminum alloys, and are of such a nature that even the slightest corrosion cannot be tolerated. Our preferred remover composition consists of amixture oi the following ingredients in the pro- 'iortions indicated: a

Percent by Parts by 7 volume weight Water l0 i0. 00 Monoethanolamine 10 10.20 Fi u e 6 g 3% 33 to e Haida l0 8. 95 Isopropyl alcohoL. 20 16. 75

the many aircraft repair fields which are located V disposed in a vertical position, 'so that its active In mixture each part of oleic acid will react with .216 parts of monoethanolamine to form a soap which serves as a carrier for the other ingredients, and the final composition will therefore be substantially as follows: 7

Percent by Parts by weight weight W r I 12. 02 10. Monoethanolamine---'. 9. 04 8. 27 Monoethanolamine oleate 13. 09 10. 89 Kerosene 9. 80, 8. 2i l-nitropropane- 36. 20 30. 09 isopropyl alcohol 18. 95 15. 75

This product is of paste-like character which is soft enough to permit its application and easy spreading .over. a painted surface with a putty knife, an ordinary wooden stick, or almost any readily available tool. At the same time it is stiff particular advantage, because it completely overcomes one of the objections to prior art removers, namely, that of difficulty of maintaining a film of the remover on the surface to be stripped.

' The composition has proven to be highly effec-.

, tive in penetrating and loosening paints. and

particularly lacquers of the kind employed as protective coatings for aircraft. It has been found that the pasty composition holds its solvent ingredients in intimate contact with a painted surface long enough to allow the solvent ingredients to penetrate the protective coating and to loosen its bond with the supporting article. The composition will, for example, completely strip an anodized aluminum alloy panel which has been finished with a-primer and enamel top coats, and will leave a surface which is suitable for refinishing without further preparation.

It is of note that the vaporpressure of the composition is very low, so that at normal atmospheric temperatures the several solvents have little or no tendency to pass away as vapors be-- fore they can accomplish their functions. Also it will be appreciated that the active ingredients which have been employed, do not give oil noxious odors whichmight constitute either a source of annoyance or a real physical hazard to operators who must apply the composition to articles to .be stripped. v

A further feature of importance is that none of the ingredients of our composition has any corrosive effect .upon aluminum alloys (either polished or anodized surfaces) which are ordinarily used in aircraft, or upon steel, cadmium plated steel, or other common materials of construetiona This is a matter of particular importance in a remover such as ours, which is intended to be maintained in mntact with metal surfaces for it renders the penetrant solvents veryiactive in attacking both baked and air-dried varnishes. Thus, we have found that the preferred composition is extremely active at ordinary temperatures, but that when the water is omitted the paint lifting action is very much slower and less effective. The exact amount of water. which is to be employed is determined to some extent by the consistency which the final product is to have. We have found that the proportion indicated above forms aremover pasteof. high effectiveness, but we recognize that a somewhat stiffer paste may be desirable at times, or that a softer one may also be useful, and accordingly that the water content may be adjusted to give a product most nearly meeting the needs of individual cases.

The monoethanolamine of the composition is an alkaline reacting solvent which is particularly e fiective in removing paints and varnishes of the resinbase type. Almost all aircraft varnishes, for

example, are based upon glycerol phthalate, and

are readily acted upon by the monoethanolamine, even after they have been hard baked. In some cases we have found that this ingredient may be replaced by diethanolamine or triethanolamine, both ofwhich will form soaps with oleic acid to give a pate-like remover, but neither of these amines is quite as effective in penetrating paints and lacquers as is the monoethanolamine preferred composition. r

'I'helkerosene constituent of the; composition may be replaced with Stoddard solvent or No. 2 furnace oil. Gasoline and painters naphtha may also be used as substitutes, but arenot preferred of the because of their low boiling points and high vapor pressures.

Mono nitropropane (CI-laCHzCI-IzNOzi in the presence of water is an effective solvent for attackingbaked resin varnishes as well as air- 'dried varnishes of the linseed ioil, China-wood oil and soya bean oil types.

oleic acid is an unsaturated fatty acidwhich, as has been indicated, reacts with the monoethanolamine constituent to form a soap: and

, secondary amyl alcohol.

The preferred form of the invention been described,-what is claimed as new is:

1. A paint and varnish remover comprising a paste-like mixture of about 12 'percentby weight of water, about 10 percent by weight of monoethanolamine, about 13 percent by weight of monoethanolamine oleate, about 10 percent by weight of kerosene, about 36 percent by weight of l-nitropropane, and about 19 percent by weight of isopropyl alcohol;

fairly long periods, as compared with ordinary.

removers which are now on the market.

Again, it will be noted that our paint remover is soluble in .water and oil so that when it has loosened a protective coating from an article, it

can readily be washed away with water, turpentine, petroleum'naphtha, gasoline, or other read -ily-available materials. The water in the foregoing composition apacter.

mixture the mono'ethanolamine to form a soap, and in which the water. is present in sufficient quantity so that the final mixture is of paste-like charpears to have a very important function in that n 3. A paint and varnishremover comprising a having of said monoethanolamine'to form a soap, and

in which the mixture is oi'rpaste-like character which maybe spread readily over painted surfaces and will adhere thereto.

4. A paint and varnish remover comprising a.

mixture of Mt 1o mu brweicht: ensemanolamine, about 8 parts ,by weight of about 30 parts. by weight otimononitropropane,

about 9 parts by weight .ot'oleic acid. about 16 parts by weight of isopropyl alcohol, and water. 7 in which said oleic acid reactswith a portion of said ethanolamine to-iorm a soap. and in which said water is present insumcient' quantity so that the final mixture is orpaste-like; character.

mm b." 110mm.

auss m. n.