Cleaning compositions for solid surfaces – auxiliary compositions – Cleaning compositions or processes of preparing – For cleaning a specific substrate or removing a specific...
Reexamination Certificate
2001-04-03
2003-12-30
Webb, Gregory E. (Department: 1751)
Cleaning compositions for solid surfaces, auxiliary compositions
Cleaning compositions or processes of preparing
For cleaning a specific substrate or removing a specific...
C510S241000, C510S365000, C510S417000, C510S427000, C510S428000, C510S506000
Reexamination Certificate
active
06670315
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This application relates to low pollution solvents and emulsions especially useful in cleaning soils from painted and unpainted metal and plastic surfaces.
2. Background Art
Numerous manufacturing operations require that metal and/or plastic surfaces be cleaned from a variety of soils. Furthermore, these surface may or may not have coatings on them. Non-exclusive examples of soils include sealants and other adhesives extruded from joints, lubricants for surface finishing operations used in the manufacture of motor vehicles, lubricants used in forming objects that are not flat from metal sheets or coils, and ink from printing plates cleaning. Non-exclusive examples of surfaces requiring cleaning include purging reservoirs and any conduits of painting systems when the type and/or color of the paint needs to be changed.
In most instances, these soils are more readily removed by organic solvents than by purely inorganic solvents such as water. Most organic solvents, however, emit vapors some of which are legally classified as air pollutants and/or as hazardous to workers who breathe the vapors. Some of these compounds are referred to as volatile organic compounds (VOCs). Reactive VOCs are capable of reacting with hydroxyl radicals and ultraviolet light close to the ground to form a potentially dangerous smog. Though most smog is caused by automobile emissions, the industrial use of VOC is also a major contributor to the formation of smog. Halogenated hydrocarbons are also potentially useful solvents for many cleaning operations. However, halogenated hydrocarbons tend to deplete the ozone layer and are therefore undesirable. For this reason, the use of most organic solvents that are effective in removing the most common soils encountered during manufacturing, particularly vehicle manufacturing, is legally restricted and/or requires expensive pollution abatement equipment.
The utilization of VOCs may be decreased by the addition of organic solvents to various aqueous cleaning solutions. Such mixtures tend to have improved cleaning ability with respect to certain organic soils, inks, and greases. However, such mixtures tend to separate in layers when stored unagitated for extended periods of time. This phenomenon is undesirable in that it requires additional steps in the cleaning process.
Accordingly, an object of this invention is to provide alternative liquid materials that will effectively remove soils encountered in manufacturing but are less polluting than the organic solvents now in use that give the most effective removal of such soils. Other more detailed, alternative, and/or concurrent objects will be apparent from the description below.
SUMMARY OF THE INVENTION
It has been found that tertiary-butyl acetate (hereinafter usually abbreviated as “t-butyl acetate”) can be mixed with more traditional solvents and/or emulsified with water to provide an effective solvent for general cleaning during manufacturing, particularly motor vehicle manufacturing. These alternative t-butyl acetate-containing solvents have hazard and/or pollution potentials substantially lower than the traditional solvents because t-butyl acetate produces vapors which are considered to be less hazardous or polluting than the traditional solvents. Various embodiments of the invention include liquid compositions for direct use in cleaning metals, processes for preparing such liquid compositions, and processes for cleaning metal and/or plastic surfaces with a composition according to the invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Reference will now be made in detail to presently preferred embodiments and methods of the invention, which constitute the best modes of practicing the invention known to the inventors.
All numerical quantities in this description indicating amounts of material or conditions of reaction and/or use are to be understood as modified by the word “about” in describing the broadest scope of the invention. Practice within the numerical limits stated is generally preferred. Also, unless expressly stated to the contrary, percent, “parts of”, and ratio values are by weight. Furthermore, the description of a group or class of materials as suitable or preferred for a given purpose in connection with the invention implies that mixtures of any two or more of the members of the group or class are equally suitable or preferred. Finally, description of constituents in chemical terms refers to the constituents at the time of addition to any combination specified in the description, and does not necessarily preclude chemical interactions among the constituents of a mixture once mixed.
In an embodiment of the present invention, a cleaning liquid composition is provided. The cleaning liquid composition of this embodiment is preferably an emulsion, and more preferably a microemulsion that is either translucent or transparent. The cleaning liquid composition comprises t-butyl acetate in an amount of about 10 to 65 percent of the total weight of the cleaning liquid composition. More preferably, the t-butyl acetate is present in an amount of about 20 to 60 percent of the total weight of the cleaning liquid composition and most preferably about 30 to 55 percent of the total weight of the cleaning liquid composition. The cleaning liquid composition further comprises water and one or more emulsifying agents. The water is present in an amount of 5 to 80% of the total weight of the cleaning liquid composition, more preferably 20 to 60% of the total weight of the cleaning liquid composition, and most preferably 30 to 50% of the total weight of the cleaning liquid composition. If the concentration of water is too large, the working liquid cleaning composition is not likely to be as effective as desired in removing many of the soils encountered during motor vehicle manufacturing, while if the concentration of water is too low, there will be little or no advantage of lower cost and/or greater viscosity (which allows the working liquid cleaning composition to be used more easily on sloping surfaces) gained by including the water.
Tertiary-butyl acetate is commercially available from Lyondell Chemical Company (Houston, Tex.). The synthesis of t-butyl acetate is well known and is described, for example, in U.S. Pat. Nos. 5,994,578; 6,018,076; and 6,194,602.
The concentration of emulsifying agent in a working liquid cleaning composition according to this invention is preferably 1 to 40% of the total weight of the cleaning liquid composition, more preferably, from 8 to 35% of the total weight of the cleaning liquid composition, and most preferably from 15 to 30% of the total weight of the cleaning liquid composition. If the concentration of emulsifying agent is too high, the cost of the working liquid cleaning composition will be uneconomical, while if the concentration of emulsifying agent is too low, the stability of the emulsion will be at risk. The emulsifying agent(s) are present in a sufficient quantity to form a stable emulsion of all of the constituents of the cleaning liquid. A stable emulsion is one that does not develop any appreciable amount of a separate phase detectable with normal human vision when stored at 25° C. without mechanical disturbance for a time period from 10 to 50 hours. More preferably, the cleaning liquid does not develop any separate phase detectable with normal human vision when stored at 25° C. without mechanical disturbance for a time period from 100 to 300 hours, and most preferably does not develop any separate phase detectable with normal human vision when stored at 25° C. without mechanical disturbance for a time period from 500 to 1000 hours. Furthermore, the cleaning liquid does not develop any separate phase detectable with normal human vision that constitutes more than 5% of the total volume so stored, more preferably the cleaning liquid does not develop any separate phase detectable with normal human vision that constitutes more than 3% of the total volume so stored, and most preferably the cleaning liquid does
Marlin Lawrence J.
Patel Bhanu D.
Brooks & Kushman P.C.
Henkel Corporation
Webb Gregory E.
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