Latex paint remover

Details Latex paint remover Latex paint remover

2001-03-20

2004-09-28

Webb, Gregory (Department: 1751)

Cleaning and liquid contact with solids

Processes

With treating fluid motion

C510S137000, C510S189000, C510S365000

Reexamination Certificate

active

06797077

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to organic cleaning compositions useful for removing dried latex paint and other lipophilic materials such as soils and adhesives.
BACKGROUND OF THE INVENTION
A common test for determining whether a dried sample of paint is oil-based or latex-based is to contact the sample with xylene. If the paint sample is latex-based, the sample will dissolve for easy removal. If the sample is oil-based, the sample will remain intact.
Because of this selective solvency, xylene has been used as a commercial latex-based paint remover, alone or together with other components. However, because it is an aromatic compound, xylene also poses a significant health and environmental risk.
Accordingly, it is desirable to provide a new latex paint remover which mimics xylene in terms of its selective removal of latex-based paints but which is more benign from a health and environmental standpoint.
SUMMARY OF THE INVENTION
This and other objects are accomplished by the present invention which is based on the discovery that isobutyl isobutyrate not only mimics xylene in terms of its selective removal of latex-based paints but is also more benign than xylene from a health and environmental standpoint.
Therefore, the present invention provides a new process for removing dried latex paint and other organic contaminants from a surface comprising contacting the contaminant with a cleaning composition composed of isobutyl isobutyrate. In addition, the present invention also provides new compositions for removing dried latex paints and other organic contaminants comprising 10 to 99% isobutyl isobutyrate, the composition preferably being essentially free of aromatic compounds and alkali metal hydroxides.
DETAILED DESCRIPTION
In accordance with the present invention, dried latex paints and other organic contaminants are removed from surfaces by contacting the surface with isobutyl isobutyrate.
Surface Contaminants
The present invention is directed primarily to removing dried latex paints.
Latex paints are typically composed of polymer particles and pigments emulsified in water. When applied to a surface, the water carrier evaporates and the polymer particles coalesce to form a coherent, pigment-containing film. Most latex paints are formulated with acrylic polymers (polymers and copolymers of acrylic acid, acrylic esters and acrylonitrile) which may include ionic cross-linkers to enhance bonding of individual polymer particles in the coalesced film.
In a typical oil-based paint, however, the film-forming specie is composed of a natural and/or synthetic polymer dissolved in a suitable organic solvent such as mineral spirits, turpentine or the like. When applied to a surface, the organic solvent evaporates and the polymer deposits on the surface as a film. Further polymerization and/or ethylenic cross-linking (curing) often occurs to make the film coherent.
Because of these differences in film-forming mechanisms, oil-based paints once dried and cured are usually stronger and tougher than their latex-based counterparts. Accordingly, latex paints are easier to remove than oil-based paints, which explains why xylene and analogous materials can effectively remove latex-based paints but not oil-based paints.
In any event, the present invention is directed primarily to removing dried latex-based paints in that the inventive compositions, like xylene, will effectively dissolve latex-based paints once dried but will leave cured oil based paints largely intact.
In addition to removing dried latex-based paints, however, the inventive compositions can also be used to remove a wide variety of other lipophilic materials. For example, the inventive compositions will remove oil-based paints prior to substantial cure. In addition, the inventive compositions will remove adhesives, inks, chewing gum, tars, greases, glues, animal fats, vegetable oils, tree sap and other lipophilic soils.
Isobutyl Isobutyrate
Isobutyl isobutyrate or “IBIB” has a unique combination of properties making it ideally suited for use in removing dried latex-based paint and other lipophilic contaminants. For example, IBIB has a solvency approximately the same as that of xylene allowing it to function like xylene in terms of removing dried latex based paints, solvating other lipophilic contaminants but leaving solvent-based paints once cured largely intact. Unlike xylene, however, IBIB has numerous other properties making it far safer and more environmentally-friendly than xylene when used in a typical home or commercial setting.
For example, IBIB has a flash point of 104° F. and therefore is considered a combustible, as opposed to a flammable, as is xylene which has a flash point of about 80° F. In addition, IBIB is essentially benign in terms of its toxicology and its propensity to cause skin irritation and eye irritation. In this connection, IBIB is considered to be non-toxic (i.e. not requiring labeling as a toxic) when tested in accordance with the protocol of the Federal Hazardous Substance Act, 16 CFR 1500.3(c)(2)(i). In addition, IBIB is not considered to be a primary skin irritant when tested according to the protocol of 16 CFR 1500.41 and 1500.3(c)(4). Similarly, IBIB is not considered to be a primary eye irritant when tested according to the protocol of 16 CFR 1500.42 and 16 CFR 1500.3(c)(4). In addition, IBIB has an MIR value of 0.86 meaning that it is considered to have a low ozone-creating potential as opposed to xylene with an MIR of approximately 7.8.
In this connection, the California Air Resources Board or “CARB”, which is part of the California Environmental Protection Agency, has ranked all commonly available volatile organic compounds and solvents in terms of their potential for producing tropospheric ozone when released into the atmosphere. Since tropospheric ozone is a precursor to urban smog, a solvent's MIR or “Maximum Incremental Reactivity” is a good indicator of its potential to produce smog. IBIB's comparatively low MIR of 0.86 indicates that it has low potential as a smog former and therefore is environmentally-friendly as well as relatively benign from a health standpoint. Xylene, on the other hand, has an MIR of approximately 7.8, depending on the isomeric mixture in the composition.
Isobutyl Isobutyrate Analogs
In addition to or in lieu of IBIB, other analogous compounds can be used to provide solvency characteristics in accordance with the present invention. For example other esters having eight carbon atoms, such as propyl heptanoate and heptyl propionate, can be used, and other esters with seven or nine carbon atoms can also be used.
Esters with six carbon atoms are easily made. However, they have low flash points and low boiling points and are therefore difficult to ship and dangerous to handle. Preferably, therefore they are avoided, although they can be tolerated in amounts up to 75 wt. %, preferably 50 wt. %, in the cleaning compositions of the present invention without undue adverse effect. Esters with ten carbon atoms, on the other hand, are more difficult to make, unduly oily and of unpredictable purity. Accordingly, they are also preferably avoided, although like the C
6
esters, they can also be tolerated in amounts up to 75 wt. %, preferably 50 wt. %, without undue adverse effect.
Mixtures of esters containing at least three of hexyl, heptyl, octyl, nonyl and decyl acetates, such as the line of mixed esters sold by Exxon Chemical Company under the designation Exxon Exxates, can also be used.
Esters with less than six carbon atoms are too volatile, while esters with more than 10 carbon are too oily, to totally replace IBIB. However, such esters can also be used for partial replacement of up to 50 wt. % of the IBIB in the cleaning compositions of the present invention without undue adverse effect.
Propylene carbonate, a four-carbon ring-structured ester, also can be used as a partial or total replacement for IBIB as it also has a desirable combination of flash point (132° F.), boiling point (242° F.) and solvency.
Other naturally occurring esters having

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