Abstract:
An abrasive paste composition. The abrasive paste is made up from an aqueous suspension of water insoluble abrasive particles of from about forty five percent (45%) to about sixty five percent (65%) by weight, from thickeners of natural or synthetic clay of from about three percent (3%) to about fifteen percent (15%) by weight, from liquid detergent of from about two percent (2%) to about twenty percent (20%) by weight, and from water of from about twenty percent (20%) to about sixty percent (60%) by weight, and optional ingredients such as dyes, humectant, and perfumes. The water based abrasive paste has abrasive particles sized to provide adequate cut without surface gouging for use in automotive painting and body repair.

Description:
FIELD OF THE INVENTION 
     The present invention relates to abrasive compositions, and more particularly to novel abrasive compositions for use in surface preparation prior to the application of new paint on selected portions of automobiles. 
     BACKGROUND 
     In the automotive paint and body industry, it would useful and desirable, when sanding cured, previously painted surfaces, to produce a uniform fine scratch in preparation for the application of new paint. It would also be useful and desirable during the sanding process to remove dirt, oil, grease, and road grime from such previously painted surfaces. 
     In order to provide background information so that the present invention may be completely understood and appreciated in its proper context, reference is made to several prior art approaches to solving the above identified objectives, as discussed below. 
     First, Ting™, a nonpatented product, relies on surfactants to clean a surface to be painted; however, it does not contain abrasives to scratch the painted surface in order provide for a mechanical bond. Therefore, when using Ting™, a 3M Brand Scotchbright™ steel wool or similar product must be used to achieve the desired scratch, in order to achieve proper mechanical bond. Unfortunately, some undetermined ingredient or ingredients in Ting™ leave a residue that must be further wiped off before paint can be applied to a Ting™ treated surface, and Ting™ is thus undesirable for this process. 
     Next, Sandfix™ is also a nonpatented product that contains abrasive particles to provide a scratch for mechanical bonding of the new paint to the old paint. However, whether due to the possible inappropriate ratio of abrasives to the suspension media, or due to the inability of the abrasive used in that product to properly cut existing paint, excess labor and product is required to prepare the surface to be painted with a proper scratch in order to assure mechanical bonding of the new paint to the existing paint. Also, the colloidal thickeners used in Sandfix™ appear to be excessive, which results in difficult removal of Sandfix™ during the rinse process. Further, the industry has recognized that Sandfix™ hardens and becomes very difficult to remove, if not completely removed while wet. Also, the dye used in Sandfix™ has a tendency to leach from beneath moldings and other parts after rinsing, and then to dry on the surface to be refinished. The dye, if not removed before painting, may necessitate repainting. Further, the absence of surfactants or detergents in this product result in it failing to fulfill the needs of the automotive paint and body industry. 
     U.S. Pat. No. 3,966,432 relates to abrasive compositions in liquid form for cleaning hard surfaces. The patent indicates, at line fifteen (15), column one (1), that &#34;the compositions are not intended for use on softer surfaces such as ordinary paint work, except possible rubbing down prior to painting.&#34; However, the abrasive particle size provided in that formula is undesirable for use in the automotive painting industry, as at line twenty five (25), column one (1), it also states that &#34;a typical particle size giving a satisfactory abrasive performance is such that substantially the whole of the particle material when dry, passes through a sieve with an aperture of one hundred four (104) microns and at least eighty percent (80%) by weight passes through a sieve with aperture of fifty three (53) microns.&#34; The one hundred four (104) micron square aperture which has a one hundred forty seven (147) micron diagonal aperture, can possibly allow a particle of one hundred forty (140) or more microns to pass therethrough, resulting in an abrasive particle capable of producing scratches too large to &#34;cover&#34; with automotive basecoat paint, due to the very low mil thickness buildup of such paints. Also, the same patent, at column three (3), line nine (9) states that it &#34;has been found desirable to include the suspending agent in a range of zero point two five percent (0.25%) to one percent (1%)--preferably the minimum amount found to be necessary in any particular formulation to maintain the abrasive in suspension.&#34; Natural or synthetic clay suspension agents in that concentration range do not provide for a paste consistency of the desired viscosity, or provide for adequate suspension of the preferred pumice abrasive, in order to obtain the desired scratch for use in the automotive paint and body industry. 
     Whatever the precise merits, features, and advantages of the above cited references, none of them achieves or fulfills the purpose of providing the automotive paint and body industry with a fast cutting, water soluble, biodegradable, environmentally safe sanding paste that cleans as it sands, as does the present invention paste composition. 
     OBJECTS OF THE INVENTION 
     It is an object of the present invention to &#34;cut&#34; or sand quicker than possible with the existing arts, while maintaining a fine enough scratch to apply automotive basecoat paints, which have very little mil thickness buildup, and which do not &#34;cover&#34; coarser scratches, while providing enough scratch for a sufficient mechanical bond with the new paint, be it basecoats, clearcoats, or a single stage paint system. 
     It is a further object of the inventive paste composition to clean as it &#34;sands&#34; or &#34;cuts.&#34; 
     Another object of the invention is to provide an easier rinse off with water than with the presently known arts. This is accomplished by using water rinseable suspending agents and by using water soluble detergents to also serve as a suspension media. 
     Still another object of the invention is to provide an environmentally safe, biodegradable product. 
     Still yet another object of the invention is to provide a product that is used in an aqueous state, thus eliminating nuisance dust which the U.S. Environmental Protection Agency (&#34;EPA&#34;) has determined to be hazardous to personnel. 
     SUMMARY 
     The foregoing objects of the present invention are accomplished in an abrasive paste composition containing by weight: 
     (a) from about 45% to about 65% of a fine abrasive; 
     (b) from 3% to about 15% clay, synthetic or natural; 
     (c) from 2% to about 20% detergent; 
     (d) from 20% to about 60% water; and 
     (e) from 0.00% to about 10% dyes, perfumes, suds stabilizers, and miscellaneous ingredients and mixtures thereof. 
     DETAILED DESCRIPTION 
     The preferred paste composition contains four essential components, and additional optional ingredients, as follows: 
     a. the abrasive; 
     b. suspending agent; 
     c. detergent; 
     d. water; 
     e. additional optional ingredients; 
     The paste composition just set forth results in the provision of an abrasive paste which is especially effective for sanding (or &#34;cutting&#34;) and cleaning of cured paints which are used in the automotive industry. The result of use of such an abrasive on a surface to be painted is a surface which (a) is clean, and (b) has sufficient scratch or &#34;cut&#34; to provide for proper mechanical bond of the new paint being applied. 
     Ideally, the paste composition contains from about forty five percent (45%) to about sixty five percent (65%) by weight of a substantially water insoluble abrasive. A number of abrasives may be used, including, but not limited to, calcite or ground marble, silica, feldspar, pumice, kieselguhr, and labradorite. Pumice is the preferred abrasive, as it has a tendency to continually break and expose new sharp edges, thus enhancing the cutting ability of the abrasive, as well as extending the life of the abrasive particles while in use. Preferred paste compositions contain from about fifty percent (50%) to about fifty eight (58%) of the pumice. Such pumice typically has particles of which seventy six percent (76%) are smaller than forty five (45) microns, and ninety seventy percent (97%) are smaller than seventy five (75) microns, with about three percent (3.0%) being between seventy five (75) microns and ninety (90) microns in size. This corresponds to one hundred percent (100%) passing through a one-hundred seventy (170) mesh size sieve, and ninety seven percent (97%) passing through a two hundred (200) mesh size sieve, and seventy six percent (76%) passing through a three hundred twenty five (325) mesh size sieve. 
     The paste composition can contain from about three percent (3.0%) to about fifteen percent (15%) by weight of a synthetic or natural clay suspending agent. More preferably the paste composition contains from about four percent (4.0%) to about eight percent (8.0%) of a natural clay suspending agent. For example, the formula (Si 8  Mg 5 .1 Li 0 .6 H 7 .6 O 24 ) 0 .6 --Na +   0 .6 represents the formula for a synthetic clay suspending agent, similar in constitution to the mineral Hectorite. Alternately, a finely ground sodium bentonite, of which seventy five percent (75%) passes through a three hundred twenty five (325) mesh sieve, available under the trade name of &#34;Big Horn CH-35&#34; from WYO-BEN, INC., is an example of a natural clay suspending agent, and has a typical chemical analysis as set forth in TABLE I. The preferred suspending agent is finely ground sodium bentonite natural clay. 
     
                       TABLE I______________________________________Composition of Sodium BentoniteConstituent   Amount Present______________________________________SiO.sub.2     60.34%Al.sub.2 O.sub.3         19.28%Fe.sub.2 O.sub.3         3.48%Na.sub.4 O    2.34%TiO.sub.2     0.22%CaO           0.38%MgO           1.67%K.sub.2 O     0.10%H.sub.2 O     7.75%Other         4.44%______________________________________ 
    
     In conjunction with the natural or synthetic clay, the surfactants in the detergent contribute to the suspension of abrasives in the paste. The composition of my paste contains from about two percent (2.0%) to about twenty (20%) by weight, and more preferably from about two percent (2.0%) to about ten percent (10%) by weight, of a liquid detergent. As an example, a suitable liquid detergent could contain an alkyl sulfate and alkyl ethoxylated sulfate, with a composition of about twenty percent (20%) to about forty percent (40%) of anionic surfactant. However, the liquid detergent may have from about twelve percent (12%) up to about sixty two percent (62%) of an anionic surfactant which has the general formula RO(C 2  H 4  O) x  --SO 3  M wherein R is an alkyl group containing from about ten (10) to sixteen (16) carbon atoms, and where M is selected from the group consisting of sodium, potassium, ammonium, monoethanol ammonium, diethanol ammonium, triethanol ammonium, calcium and magnesium cations, and mixtures thereof, and the ethoxylate is such that, on a molar basis the compounds wherein x is zero (0) are from about fifty four percent (54%) to about sixty percent (60%), and wherein x is one (1) are from about fifteen percent (15%) to about twenty percent (20%), and wherein x is two (2) are from about ten percent (10%) to about thirteen percent (13%), and wherein x is three (3) are from about six percent (6.0%) to about seven percent (7.0%) of the total, and there is sufficient magnesium to at least neutralize fifty percent (50%) of the anionic surfactant wherein x is zero (0). Also, from one point two five percent (1.25%) to about twenty five percent (25%) of a suds stabilizer, and from about zero (0.00%) to about twelve point five percent (12.5%) of a detergency builder selected from inorganic silicates, carbonates, and organic carboxylates, and mixtures thereof, are included in the liquid detergent. 
     The paste composition of the present invention may contain from about twenty percent (20%) to about fifty percent (50%) by weight of water, and more preferably from about thirty five percent (35%) to about forty five percent (45%) by weight of water. 
     The paste composition of this invention may also consist of from about zero percent (0.00%) to about ten percent (10%) by weight of additional optional ingredients. Such ingredients are used to provide performance and aesthetic characteristics. For example, a humectant to prevent drying out of the composition, sorbitol being an example, may be desirable. Also, perfumes, coloring agents or dyes, or other agents may be desirable. 
     The preferred manufacturing procedure according to the present invention consists of: 
     (a) thorough mixing of water, the suspending agent, and the optional ingredients; 
     (b) adding the desired abrasive, and adding the desired detergent; 
     (c) pulling a vacuum of up to fifteen (15) inches of mercury or higher, and thoroughly mix. 
     Mixing the paste in a vacuum alleviates the need for consequent deaeration. 
    
    
     EXAMPLES 
     The following examples illustrate the invention. 
     Examples 1-3 
     The present invention, having the following composition by weight, is formulated: 
     
         ______________________________________Ingredient      Ex. 1      Ex. 2   Ex. 3______________________________________Pumice          50.0%      55.0%   51.7%Bentonite       5.0%       10.0%   5.2%Detergent RO(C.sub.2 H.sub.4 O).sub.x -SO.sub.3 M           2.0%       10.0%   3.8%Water           42.5%      24.5%   38.8%Dye, perfume, etc.           0.5%       0.5%    0.5%______________________________________ 
    
     Example 3 has the best consistency and combination of sanding, cleaning, and suspension properties, and is the preferred blend of ingredients. 
     The foregoing description of the preferred embodiment of the invention has been presented for the purpose of illustration and description. It is not intended to be exhaustive or to limit the invention to the present precise form disclosed. Many modifications and variations are possible in light of the above teachings. It is intended that the scope of the invention be limited not by this detailed description, but rather by the claims appended hereto.