Cleaning compositions for solid surfaces – auxiliary compositions – Cleaning compositions or processes of preparing – For cleaning a specific substrate or removing a specific...
Reexamination Certificate
1999-08-04
2001-10-16
Delcotto, Gregory (Department: 1751)
Cleaning compositions for solid surfaces, auxiliary compositions
Cleaning compositions or processes of preparing
For cleaning a specific substrate or removing a specific...
C510S174000, C510S201000, C510S203000, C510S206000, C510S207000, C510S210000, C510S212000, C510S213000, C510S279000, C510S370000, C510S499000, C510S505000
Reexamination Certificate
active
06303552
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to aerosol paint stripper compositions and methods of preparing the same.
BACKGROUND OF THE INVENTION
For decades, strong acids and halocarbon solvent-based compositions were employed in stripping various protective coatings from metal and other substrates. Increased awareness of the detrimental impact of such paint strippers on health and environment, in recent years, resulted in government legislative bodies all over the world restricting and/or prohibiting the use of these materials.
Various hazardous solvents, such as methylene chloride and methyl alcohol, are often included in paint stripper compositions. Since these solvents may cause health and environmental problems when airborne, they are not suitable for use as an aerosol.
There is a need for effective paint stripper compositions which do not contain strong acids, halocarbon solvents, or other hazardous solvents and which may be applied as an aerosol.
SUMMARY OF THE INVENTION
The present invention is directed to an aerosol composition comprising (A) a paint stripper composition comprising (i) from about 5 about 50% by weight of aromatic alcohol, (ii) from about 0.5 to about 5.0% by weight of an accelerator, and (iii) from about 15 to about 60% by weight of water, based upon 100% weight of total paint stripper composition; and (B) a propellant. The aerosol composition of the present invention is environmentally safe and non-hazardous. It is also non-corrosive or only slightly corrosive to substrates, nonflammable, nontoxic, low odor, and fully biodegradable.
Another embodiment of the invention is an aerosol can containing the aerosol composition of the present invention.
Yet another embodiment of the invention is a method of preparing the aerosol composition comprising the steps of (A) dispersing (i) a polar phase containing (a) from about 10 to about 45 parts by weight of water and (b) from about 0.3 to about 4 parts by weight of an accelerator into a (ii) a non-polar phase containing from about 3 to about 35 parts by weight of aromatic alcohol to form a paint stripper composition, and (B) adding from about 20 to about 50 parts by weight of a propellant to the paint stripper composition to form the aerosol composition.
Yet another embodiment of the invention is a method for removing paint or a coating from a substrate comprising applying a paint or coating removing effective amount of the aerosol composition of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
The aerosol composition of the present invention comprises (A) a paint stripper composition and (B) a propellent. The paint stripper composition of the present invention comprises (i) from about 5 to about 50% by weight of (a) an aromatic alcohol having the formula
where X, Y, and Z are all hydrogen or two hydrogens and a methyl, (b) an aromatic alcohol having the formula
where R is ethylene, propylene, or isopropylene, or (c) a mixture thereof; (ii) from about 0.5 to about 5% by weight of an accelerator; and (iii) from about 15 to about 60% by weight of water, based upon 100% weight of total paint stripper composition.
The paint stripper composition typically has a pH of from about 10 to about 11.
Suitable aromatic alcohols include, but are not limited to, benzyl alcohol, phenoxy propanol, phenoxy ethanol, and any combination of any of the foregoing. Preferably, the aromatic alcohol is benzyl alcohol. The composition preferably comprises from about 30 to about 40% by weight of aromatic alcohol, based upon 100% weight of total paint stripper composition.
Suitable accelerators include, but are not limited to, alkanolamines, such as monoethanolamine, triethanolamine, and any combination of any of the foregoing. Preferably, the composition contains both monoethanolamine and triethanolamine. The weight ratio of monoethanolamine to triethanolamine is preferably from about 2:1 to about 1:2 and more preferably about 1:1. The composition preferably comprises from about 0.5 to about 3% by weight of an accelerator, based upon 100% weight of total paint stripper composition.
The presence of deionized water in the composition enhances the overall stripping effectiveness of the composition. When the protective coating on a substrate to which the composition is applied is polar, e.g., polyurethanes, the presence of a solvent with a high dielectric constant such as water (&egr;=80.2@20° C.) has a positive effect in separating charged areas, thus allowing other solvents in the composition to soften the coating.
The water preferably contains no more than about 1% by weight of dissolved inorganic salts and preferably less than about 200 ppm. Distilled or deionized water having an electrical conductivity less than about 400 mho/cm is particularly preferred.
The paint stripper composition preferably comprises from about 30 to about 60% by weight of water, based upon 100% weight of total paint stripper composition.
Corrosion inhibitors may be added to the paint stripper composition to control the corrosive action of the composition on an aerosol spray can as well as on metal substrates on which the composition is applied. Suitable corrosion inhibitors include, but are not limited, 2-mercaptobenzothiazole, toluoltriazole, benzotriazole, 2(3H)-benzothiazolethione, morpholine, sodium nitrite, sodium benzoate, and any combination of any of the foregoing. Preferred corrosion inhibitors include, but are not limited to, 2-mercaptobenzothiazole, morpholine, sodium nitrite, sodium benzoate, and any combination of any of the foregoing. The paint stripper composition typically comprises a corrosion inhibiting or corrosion retarding effective amount of corrosion inhibitor. Preferably, the paint stripper composition comprises from about 0.1 to about 3% by weight and more preferably from about 0.5 to about 1% by weight of corrosion inhibitor, based upon 100% weight of total paint stripper composition.
The paint stripper composition may also include an aromatic ether having the formula R
1
—CH
2
—O—CH
2
—R
2
where R
1
and R
2
are hydrogen and phenyl or both phenyl. A preferred aromatic ether is benzyl ether. The paint stripper composition preferably includes from about 1 to about 20% by weight of aromatic ether based upon 100% weight of total paint stripper composition. The weight ratio of aromatic alcohol to aromatic ether is preferably from about 10:1 to about 5:1 and more preferably about 7:1.
An aromatic hydrocarbon cosolvent may be included in the paint stripper composition. The aromatic hydrocarbon cosolvent may be a mixture of one or more aromatic hydrocarbon solvents. The aromatic hydrocarbon cosolvent improves the stability of the paint stripper composition thereby increasing the shelf life of the composition. It also improves the rheological properties of the paint stripper composition and the speed of penetration of the composition into paints and coatings. Furthermore, the aromatic hydrocarbon solvent reduces the surface tension and evaporation rate of the paint stripper composition. Preferably, the aromatic hydrocarbon solvent has a flashpoint above about 150° F. and more preferably above about 190° F. Naphthalene depleted aromatic hydrocarbons are preferable since naphthalene has a noxious odor and is hazardous. Suitable aromatic hydrocarbon cosolvents include, but are not limited to, Aromatic 200ND™ available from Exxon Chemical Co. of Houston, Tex.; Solvesso 200™ available from Esso Corp. of Toronto, Canada; metaphenoxy benzyl alcohol; and any combination of any of the foregoing. The paint stripper composition typically comprises from about 0.5 to about 40% by weight and more preferably from about 1 to about 20% by weight of aromatic hydrocarbon cosolvent based upon 100% weight of total paint stripper composition. The weight ratio of water to aromatic hydrocarbon cosolvent is typically from about 1.5:1 to about 30:1 and preferably from 3:1 to about 30:1.
The paint stripper composition may include other adjuvants, such as coupling agents, rheology modifying agents, evaporation retardants, solubilizer-ernul
Darby & Darby
Delcotto Gregory
Napier International Technologies Inc.
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