Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D7/00—Processes, other than flocking, specially adapted for applying liquids or other fluent materials to particular surfaces or for applying particular liquids or other fluent materials
  • B05D7/50—Multilayers
  • B05D7/52—Two layers
  • B05D7/53—Base coat plus clear coat type
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D5/00—Processes for applying liquids or other fluent materials to surfaces to obtain special surface effects, finishes or structures
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G18/00—Polymeric products of isocyanates or isothiocyanates
  • C08G18/06—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen
  • C08G18/28—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen characterised by the compounds used containing active hydrogen
  • C08G18/40—High-molecular-weight compounds
  • C08G18/42—Polycondensates having carboxylic or carbonic ester groups in the main chain
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
  • C09D163/00—Coating compositions based on epoxy resins; Coating compositions based on derivatives of epoxy resins
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
  • C09D175/00—Coating compositions based on polyureas or polyurethanes; Coating compositions based on derivatives of such polymers
  • C09D175/04—Polyurethanes
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
  • C09D9/00—Chemical paint or ink removers
  • C09D9/04—Chemical paint or ink removers with surface-active agents

Definitions

• This invention relates to means for facilitating removal of unwanted substances, such as graffiti, from walls or similar surfaces. Specifically, this invention relates to the pre-treatment of surfaces with environmentally safe coatings which allow removal of contaminants and graffiti from the surface without degradation of the underlying coating.
• One of the most commonly used graffiti removal systems at present comprises coating a surface with a substance which is thereafter removed when soiled by graffiti or other material. Such systems are commonly referred to as “sacrificial coatings" since the coating is removed after soiling and must be replaced to provide further protection from graffiti and other contaminants.
• Other graffiti removal systems provide obliterative coatings for covering graffiti already applied to a surface. A system of that type is described in U.S. Patent No. 4,716,056 (referenced previously) in which a colored water-based epoxy coating is applied over a graffitied surface followed by an aliphatic urethane top coating.
• both the water-based epoxy and urethane coatings described therein are pre-reacted (i.e., cross-linked prior to mixing or application) and are able to be applied only after addition of a solvent and a hardener, the coatings are susceptible to degradation from application of solvent during cleaning. That is, integrity of the polymers is compromised upon subsequent application of solvent.
• a number of polymer coatings presently on the market which purport to be formulated for the easy removal of graffiti therefrom are cured by solvent evaporation. While such coatings have some advantages over older formulations, they are susceptible to degradation from the solvents in spray paints used for making graffiti. That is, the solvents in spray paints weaken the polymeric integrity of the coating and a portion of the spray paint becomes imbedded in the coating as it cures. This is particularly prevalent when the graffiti is not removed within thirty-six hours after application. When cleaned, a residual amount of graffiti remains on the coating.
• Solvent evaporation-cured coatings as well as chemically cross-linked polymeric coatings currently on the market may be sufficiently cleanable to remove an acceptable amount of graffiti therefrom, but repeated cleanings tend to weaken the polymeric bonds of these coatings so that the coating becomes ineffective or permanently stained after a relatively few number of cleanings.
• a graffiti removal system comprising a non-sacrificed polymeric protective coating which is not susceptible to degradation when solvents and cleaners are applied, and which has a low volatile organics content thereby rendering the coating safe for the environment and users, and a non-toxic, biodegradable cleaner for removing graffiti from the protective coating which does not affect or degrade the coating.
• a graffiti-removal system which includes a protective coating for application to an underlying surface, the coating being either a water-based epoxy or an aliphatic urethane material having a low volatile organics content, and a non-toxic, biodegradable cleaner.
• the coatings of the present invention provide a strong and impenetrable surface which is neither degraded nor compromised by the application of solvents or cleaners and which is particularly unaffected by application of the biodegradable cleaner of the invention. That is, the cleaner, when applied to the coating, will not compromise the integrity of the protective coating, but will effectively remove graffiti therefrom.
• the protective coatings of the invention are suitable for application to many surfaces for the easy removal of unwanted contaminants therefrom, such as industrial byproducts and wastes. However, this disclosure focusses on removal. of graffiti as an exemplar.
• the protective coating of the invention is applicable to a variety of surfaces, including but not limited to stone, -masonry, brick, wood and metal, which have been properly prepared.
• the protective coating is generally a nonpre-reacted polymer material which cures by chemical cross-linking producing a high bond density. The coating bonds effectively to any surface. After being contaminated by graffiti, or some other unwanted substance, the protective coating is contacted with cleaner to remove the graffiti.
• the protective coating is neither affected by the cleaner nor by the contaminants placed thereon, such as solvent-based paints.
• the coating is particularly formulated to be unaffected by prolonged application (greater than fifteen minutes) of one hundred percent concentrated N-methyl pyrrolidone. All other known coatings will degrade (i.e.
• the protective coating may be cleaned continuously (more than one hundred times) without any need for reapplication of the coating.
• the protective coating of the present invention also has excellent weatherability and is resistant to chalking, flaking and yellowing (i.e., no chalking, flaking or yellowing is observed after the coating has been subjected to environmental forces for over three months) .
• the protective coating may be a water-based epoxy which is water soluble and has a low volatile organics content (about 0.059 kg to about 0.24 kg per liter [about 0.05 to about 2.0 pounds per gallon]).
• the water-based epoxy coating generally comprises a two component system which provides mixture of the polymeric components to initiate cross-linking of the polymers. Cross-linking of the mixture after being applied to the surface assures integrity of the coating against subsequent application of solvents.
• An epoxy resin, a polyamide resin, an ether diluent, water, a flow agent and a coalescing agent are included in the formulation.
• the water-based epoxy may be used in a clear state, or color additives may be mixed therewith.
• color additives are most desirably used with the water-based epoxy coating.
• the water-based epoxy coating is easily applied, provides easy clean-up, has very little odor and dries to a hard, porcelain-like finish.
• the coating is very durable and is resistant to staining or damage by abrasion.
• the coating is very easily cleaned.
• the water-based epoxy coating may be formulated with a gloss, semi-gloss or flat finish.
• a nonpre-reacted aliphatic urethane generally comprising a polymer having a reactive site which reacts with an isocyanate, an isocyanate, a hydrocarbon-based solvent or mixture of solvents and flow agents.
• the aliphatic urethane is formed from two components which, when mixed, initiate cross-linking of the polymers.
• the polymers selected for use in the coating have a greater content of reactive groups per unit weight thereby producing a high density of cross- linkages, and the coating is therefore particularly resistant to subsequent application of solvents.
• the urethane coating has the advantage over water-based epoxy of being usable in a clear state. That is, urethanes are not subject to a yellowing tint, so the aliphatic urethane coating may be used in the clear state.
• the urethane coating may also be supplemented with pigments, and may be formulated with either a gloss, semi-gloss or flat finish.
• the aliphatic urethane coating inherently has a higher volatile organics content (VOC) than the water- based epoxy. Nonetheless, the VOC of the aliphatic urethane coating is still comparatively small, ranging from about 0.24 kg to 0.36 kg per liter (2.0 to about 3.0 pounds per gallon) .
• the urethane coating may not be suitable for application in those areas.
• the urethane coating provides a fast-drying, tough and durable finish to all manner and form of surfaces, including wood, metal, drywall, plaster, masonry and the like.
• the applied coating is stain resistant, easy to clean and is abrasion resistant. Both coatings may be applied to previously untreated surfaces or pre-treated surfaces, such as painted surfaces. The surfaces should be properly prepared prior to application of the coating. Any conventional means of application, such as brushing, spraying, or rolling, may be used to apply the coatings to a surface.
• the coatings are generally desirable to apply with a suitable thickness of material to assure coverage of previously treated surfaces, such as painted walls, and to assure a comprehensive protective coating. Under many conditions, a single application of the coating of the invention is sufficient. Subsequent coats may be applied as necessary. It is possible, though not required, to make an application of one type of coating, either the water-based epoxy or the urethane, followed by an application of the other type of coating. Because the urethane coating may slightly alter the color of some surfaces (i.e., it produces a "wet look") it may be desirable to initially apply a barrier/sealant.
• the coatings of the present invention may be cleaned with a number of different materials. Water may be used to flush the soiled coating where appropriate. Any number of commercially available cleaners, such as acetone, xylene and other industrial solvents, may also be used on the coatings without damaging the coatings.
• a biodegradable cleaner which is non-toxic and safe for use near water sources.
• the water soluble cleaner dissolves all types of epoxy and urethane paints and indelible marking inks.
• the cleaner is formulated to act upon the protective coating to remove contaminants therefrom while not compromising the integrity of the protective coating.
• the cleaner generally comprises N-methyl pyrrolidone in a concentration greater than fifty percent by weight and a surfactant.
• the graffiti material begins to bead and lift away from the protective coating.
• the graffiti and cleaner may then be wiped off with a cloth or, preferably, may be washed away with a pressurized water spray, such as a squirt bottle.
• the biodegradable cleaner may be used to clean surfaces not coated with the protective coatings of the present invention.
• the combination of pre-packaged coating components and cleaner provides a convenient means for the user to mix the two components and apply the mixture to a surface to produce an impenetrable protective coating, and to easily clean the protective coating after graffiti or other unwanted substances have been placed on the cured coating.
• the graffiti-removal system of the present invention includes a protective coating for application to a surface and a biodegradable cleaner, as described further hereinafter.
• the water-based epoxy protective coating material is formed from two separate chemical mixtures, one component being a base and the second component being a reactant.
• the coating is formed of two separate components in order to provide non-reacted materials since pre-reacted coatings tend to result in lessened strength or integrity of the coating once applied to the surface.
• the base component includes a bisphenol A epoxy resin having an equivalent weight of from about 100 to about 500.
• molecular weight refers to the sum of the weight of each molecule in the polymer and, therefore, carries no dimensional designation, and equivalent weight is calculated as the molecular weight divided by the functionality of the polymer.
• a particularly suitable resin is 331 Epoxy Resin made by Dow Chemical Company (Midland, Michigan; product code 19248) .
• the 331 Epoxy Resin is formed from the reaction of epichlorohydrin and bisphenol A, has a preferred equivalent weight of 190, a functionality of 2.0, and a molecular weight of 380.
• the amount of resin in the base component may be increased to produce a gloss finish in the coating. For a flat finish, less resin is present in the base and a flatting agent, such as magnesium silicate, diato aceous silica or fumed silica, is added.
• the base component also includes a glycidyl ether diluent which facilitates thinning of the material and facilitates curing.
• the glycidyl ether diluent has an equivalent weight of from about 50 to about 350.
• a particularly suitable diluent is Epodil 732 made by Pacific Anchor Chemical (Los Angeles, CA) which has a molecular weight of about 165.
• a coalescing agent and defoamer are also part of the base component and serve to coalesce the water and solvent phase of the coating.
• a particularly suitable coalescing agent is a nonylphenol ethoxylated-type agent, such as Igepal Co-897 made by Rhone-Poulenc (Louisville, KY) .
• a particularly suitable defoamer may be a mixture of silicone in paraffin-based mineral oil.
• Byk®-034 Defoamer made by BYK-Chemie USA (Wallingford, CT) is appropriate for use in the base component.
• Byk®-034 has a density of about 0.84 to 0.88 g/cm 3 at 20°C and a refractive index of 1.472 to 1.482.
• the base component further includes either 2- butoxyethanol or ethylene glycol monobutyl ether as a water-miscible solvent.
• Butyl Cellosolve® Solvent having a molecular weight of 118.18, made by Union Carbide (Danbury, CT) may be particularly suitable for this purpose.
• An amount of water is also added. The water may be from the tap, de-ionized or distilled.
• a silicone additive such as BYK®-370 (BYK Chemie Co. ; equivalent weight of 48) may be added in the amount of about 1% to 5% of the total volume to render the coating more repellent and resistant to scratching.
• a pigment or coloring agent may preferably be added to the base component since epoxy inherently produces a yellowish tint in the clear state. Any number of coloring agents may be added depending on the desired color. Examples of pigments include titanium dioxide, red iron oxide, black iron, yellow iron oxide, and the like. However, the water-based epoxy may be used in the clear state if desired.
• the reactant component of the water-based epoxy protective coating includes a polyamide resin having an equivalent weight of about 50 to about 600, isopropanol (about 50% to about 99% by concentration) , and water.
• the polyamide resin serves as a curing agent in the formation of the coating.
• Particularly suitable polyamide resins for use in the reactant component are Casamid 360W and Casa id 362W, both made by Pacific
• Casamid 360W has a preferred equivalent weight of 160 and a specific gravity of 1.05 at 20 ⁇ C (68 ⁇ F).
• the protective coating of the present invention may also be an aliphatic urethane having a low volatile organics content (VOC) formed from two separate components, a base component which includes a polymer having reactive sites capable of reacting with isocyanates and a reactant component, which provide initiation of cross-linking of the polymeric components upon mixing.
• VOC volatile organics content
• the aliphatic urethane coating is primarily characterized by the impenetrable surface it provides due to the high density of cross-linkages in the polymer as compared to other types of cross-linked polymeric coatings.
• the aliphatic urethane coating is thus resistant to penetration of any substance, such as solvents or foods, is stain-resistant and weather- resistant, and is not compromised or affected by application of any cleaner.
• the aliphatic urethane coating is formulated to withstand application of high concentrations (50% to 100% by weight) of N- methyl pyrrolidone without effecting the integrity of the cross-linkages in the coating.
• the base component of the aliphatic urethane coating includes a polymer or monomer having a hydroxyl or amine content (i.e., the percent of the OH or NH 3 weight relative to the weight of the molecule) in the range of 1.0% to 94.0%.
• Suitable materials include acrylic polyols, polyether polyols, polyamines and ethylene or propylene glycols. Particularly suitable is a saturated polyester polyol having an equivalent weight of from about 150 to about 1300.
• Desmophen 650A-65PMA Mobay Corp., Pittsburgh, PA
• Desmophen 650A-65PMA Mobay Corp., Pittsburgh, PA
• the base component also includes a solvent or mixture of solvents, and suitable solvents include methyl ethyl ketone, n-butyl acetate, xylene, glycol ethers and acetates thereof, such as propylene glycol monomethyl ether acetate (PM Acetate) , toluene, methyl isobutyl ketone, methyl amyl ketone, ethyl acetate and 1-1-1 trichloroethane (used in low VOC formulations) .
• a metal- containing accelerator, or catalyst, selected for reactivity of cyano (NCO) and hydroxyl (OH) groups or cyano (NCO) and amine (NH 2 ) groups may be added to the base component.
• Such catalysts include tributyltinoxide, dibutyltin dilaurate and metal carboxylates.
• Flow agents may be added to the base component to improve handling of the substance. Examples of such flow agents include a combination of an ethyl acrylate and 2-ethyl hexyl acrylate (Modaflow®) , polysiloxanes, acrylics and polyacrylics, acrylates and polyacrylates and silicones.
• a surface additive such as hydroxy polydimethylsiloxane, hydroxy polydialkylsiloxane or similar siloxane or silicone compounds, may be added to enhance the abrasion-resistant characteristic of the coating.
• a particularly suitable silicone additive is BYK®-370 (BYK Chemie, Wallingford, CT) .
• the aliphatic urethane coating may be formulated in gloss, semi-gloss or flat finishes, and may be clear or pigmented.
• silicate flatting agents such as magnesium silicate (talc) , diato aceous silica or fumed silica, may be used to produce a flat finish.
• anti-settling agents may be added, such as a bentonite, polyamide, polyolefin, or polyether esters.
• the coating may be pigmented with any pigment, colorant or dye commonly used in the industry.
• the reactant component of the aliphatic urethane coating includes an aliphatic polyisocyanate having a cyano (NCO) content (i.e., percentage of the weight of the cyano group relative to the weight of the molecule) ranging from about 3.0% to about 50.0%, a molecular weight of from about 100 to about 5,000 or greater, and an equivalent weight of from about 100 to about 500.
• a preferred molecular weight may be about 850.
• Exemplar materials include hexamethylene diisocyanate, isophorone diisocyanate, diphenylmethane 4, 4' diisocyanate and toluene diisocyanate.
• a particularly suitable material is Desmodur N- 75 (Mobay Corp., Pittsburgh, PA) which has a preferred equivalent weight of 255, a functionality of 3.3 to 3.5, a molecular weight of between 841.5 and 892 and an NCO content of about 16.5%.
• Desmodur N-75 for example, is pre-formulated with butyl acetate and xylene, but these or other solvents may be added to a diisocyanate material as needed.
• a water-binding agent such as an alkyl ortho formate, may need to be added to the reactant component to absorb water, particularly when the reactant component has been sitting -for some time.
• a typical clear coating in either a flat, gloss or semi-gloss finish, will contain from between about 29% to about 33% by weight of curable polymer (such as a polyester polyol) , between about 23% to about 27% by weight of reactant (such as a diisocyanate) , between about 37% to about 45% by weight of solvent or combined solvents (such as MEK, xylene and the like) and between about 0% to about 4.5% by weight of other materials, such as flatting agents, silicates, flow agents or an accelerator.
• curable polymer such as a polyester polyol
• reactant such as a diisocyanate
• solvent or combined solvents such as MEK, xylene and the like
• the typical composition will contain about 27% by weight of curable polymer, about 18% by weight of reactant, about 33% by weight of solvent or mixed solvents, about 2% by weight of other materials (flatting agents, flow agents, etc.), and about 25% by weight of titanium dioxide.
• the surface Prior to application to a surface of either the water-based epoxy coating or the aliphatic urethane coating, the surface must be prepared.
• the surface may be previously painted.
• the surface to be coated should be free from wax, grease, oil or like materials. If the water-based epoxy is to be applied, the surface need not be free of moisture since moisture, if not free standing, is not detrimental to application or performance of the coating. However, if the aliphatic urethane is to be applied, the surface should be dry. When applying either coating, any glossy, glazed or dense surfaces must be dulled prior to application.
• any patching or seaming of surfaces should be completed before application.
• Concrete block or similar rough surfaces may be filled with an acrylic block filler.
• Metals should be primed with a rust inhibiting primer.
• the primer should be allowed to dry at least six hours before applying the protective coating of the present invention. Thirty minutes before application, equal amounts of the base component and the reactant component of the water-based epoxy coating are mixed together by stirring. A lifting motion should be used to assure complete mixing.
• the pot life of the admixture is at least four hours and, if desired, the mixture can be refrigerated to extend pot life.
• the dual-component mixture may be applied to the target surface by any conventional means, such as brushing or spraying.
• the surface temperature should be from about 10°C (50°F) to a maximum of 35°C (95°F) . Application should be done when the ambient temperature is above 10°C (50 ⁇ F) and not greater than about 30 ⁇ C (85°F) .
• An amount of 3.785 liters (one gallon) of water-based epoxy coating will cover about 14 square meters to about 19 square meters (about 150 to about 200 square feet) .
• the resulting coverage may be about 0.051 mm to 0.10 mm in thickness (about 0.002 inch to about 0.004 inch) depending on surface porosity and application method and number of applications.
• the coating is tack-free in about an hour, and a recoat may be reapplied after six hours.
• the coating is completely cured at between 24 to 48 hours.
• the water-based epoxy coating of the present invention will not lift prior alkyd or latex finishes having a gloss or sheen. In most cases, a single coating of the water-based epoxy coating is sufficient to protect the underlying surface from damage and will provide a coating which is easily cleaned after application of graffiti or other material.
• Equipment used in applying the water-based epoxy system, and the surrounding area, may be easily cleaned with soap and water. If equipment is used for long periods of time or is allowed to sit unused for an extended period of time, a washing solvent may be required to clean the equipment.
• a particular useful barrier is a water-based coating comprising an acrylic copolymer, siloxane, dimethyl carbinol, water, flow additives and coalescing agents.
• One or two coats may be applied to a prepared surface, as required or desired. A thin coat, not exceeding 0.051 mm (0.002 inch), is recommended.
• a one to four ratio of base component and reactant component' of the aliphatic urethane coating may be mixed together using an upward motion to assure complete mixing.
• the mixture has a pot life of at least four hours and may be refrigerated to extend pot life.
• one gallon will cover about 14 square meters to about 19 square meters (about 150 to about 200 square feet) with a resulting coating thickness of from about 0.051 mm to about 0.10 mm in thickness (about 0.002 inch to about 0.004 inch), depending on the surface porosity and texture, and the method of application.
• Application should be done on surfaces having a temperature of less than 35°C (95°F), and should be done when the ambient temperature is between about 10°C (50°F) and 30°C (85 ⁇ F) .
• the coating is tack-free after one hour, and a subsequent coat may be applied after six hours.
• the coating is substantially cured at about 24 to 48 hours and fully cured at 7 days.
• Equipment must be cleaned promptly after application of the aliphatic urethane coating.
• the equipment may be cleaned with either xylene, lacquer thinner or n-butyl acetate. If the equipment has been allowed to sit for a long period of time and the coating has begun to harden on the equipment, the cleaner described hereinafter might be effective to clean the equipment.
• the aliphatic urethane coating of the present invention is particularly suited for graffiti control because it provides a Jiardened (85 D Shore) surface which is abrasion-resistant, chemical-resistant and high- temperature resistant (93.3°C).
• the coating is permeable to air making it suitable for architectural use.
• the coating is also weather-resistant as shown in TABLE I, below.
• the aliphatic urethane coating of the present invention was compared with other coatings currently marketed and used as anti-graffiti coatings in application of 100% concentration N-methyl pyrrolidone with the results shown in TABLE III.
• the four coatings a) the aliphatic polyester urethane of the present invention (APU) , b) ProSoCo Graffiti Control A&B of ProSoCo, Inc., Kansas City, KS (ProSoCo) , c) Tex-Cote®
• the graf iti-removal system of the present invention is specifically designed to employ a cleaner which is formulated to remove graffiti and other unwanted materials from the surface of the disclosed protective coatings without compromising or harming the protective coatings.
• the cleaner is selected to be non-toxic, biodegradable and safe for use in or near water sources.
• N-methyl pyrrolidone is most conducive to cleaning of contaminants from surfaces but is destructive to solvent- evaporated coatings or polymeric coatings having low density cross-linking (see immersion tests of TABLE III) . Therefore, the present coatings are formulated to withstand N-methyl pyrrolidone in concentrations greater than 95% by weight.
• the cleaner also includes a surfactant which acts with the N-methyl pyrrolidone to provide complete cleaning of the surface and may contain an oil-based fragrance.
• the surfactant may be either anionic or nonionic, and may be in either a powder or liquid form.
• a particularly suitable surfactant is Plurafac D-25, an anionic surfactant made by BASF (Parsippany, NJ) which acts in the manner of a chelating agent.
• the cleaner is effective for removing unwanted materials from surfaces having a protective coating.
• the cleaner may be applied to a graffitied surface by any number of means, including spraying or brushing it on, applying with a cloth, or the like.
• the cleaner should be slightly agitated or rubbed onto the graffitied surface with a brush or cloth.
• Water is then applied against the surface at a pressure of between 275,800 to 827,400 Newtons per square meter [40 to 120 psi] . Water applied from a squirt bottle will often suffice.
• the water should be directed downwardly to allow the graffiti and cleaner to flow downwardly off the surface.
• the cleaner of the invention may be used on other surfaces other than those coated with the water- based epoxy or aliphatic urethane coatings disclosed herein.
• the cleaner is effective for removal of epoxy- and urethane-based spray paints of the kind typically used for graffiti, indelible inks, industrial chemicals, food stains, solvents, and other substances.
• the base component of the water-based epoxy may be formed by the following method:
• EXAMPLE A In a large container, twenty-five percent by weight of 331 Epoxy Resin (Dow Chemical) , three percent by weight of Epodil 732 (Glycidyl ether diluent) , one percent by weight of Igepal Co-897
• the reactant component of the water-based epoxy coating may be formed by the following method:
• EXAMPLE B In a large container, fifty-eight percent by weight of Casamid 360W polyamide resin, fifteen percent by weight of isopropyl alcohol (99% by concentration) and twenty-seven percent by weight of tap water were added together and stirred at room temperature for approximately ten minutes until blended. The resulting mixture was measured at .98 kg/1 (8.24 pounds per gallon) .
• the base component of the aliphatic urethane coating may be formed by the following method:
• EXAMPLE C In a large container, about fifty percent by weight of Desmophen 650A-65 PMA was added to about seven percent by weight of methyl isobutyl ketone. To that was added about fifteen percent by weight of xylene (Ashland Chemical, Columbus, OH) , about twenty- seven percent by weight of n-butyl acetate (urethane grade) and about one percent by weight of BYK 370, a hydroxy polydimethylsiloxane (BYK-Chemie USA, Wallingford, CT) .
• a mixture of about 0.2 percent by weight of combined ethyl acrylate and 2-ethylhexl acrylate copolymer (Modaflow®, Monsanto, St. Louis, MO) was added as a flow agent. The entire mixture was stirred for about ten minutes at room temperature. The resulting mixture was measured at .98 kg/1 (8.273 pounds per gallon) .
• the reactant component of the aliphatic urethane coating may be formed by the following method: EXAMPLE D: In a large container, about sixty- nine percent by weight of Desmodur N-75, a polymeric hexamethylene diisocyanate, was added to about fifteen percent by weight of xylene, about fifteen percent by weight n-butyl acetate, and about one percent by weight of alkyl ortho formate. The mixture was stirred about ten minutes at room temperature. The resulting mixture was measured to be .98 kg/1 (8.227 pounds per gallon).
• a method of forming the cleaner is set forth as follows:
• EXAMPLE E To approximately ninety-eight percent by weight of N-methyl pyrrolidone was added about two percent by weight Plurafac D-25 surfactant, and the mixture was stirred at room temperature. The mixture may be stored at room temperature in air-tight containers indefinitely.
• the cleaner may also be formulated as a paste by the addition of a thickening agent, as follows: EXAMPLE F: To approximately 95% by weight of
• N-methyl pyrrolidone was added about 5% by weight Aerosil®200 (Degussa Corp., Richfield Park, NJ) [a fumed silica], 2% by weight of Plurafac D-25 [surfactant] and 1% by weight fragrance, and the mixture was combined into a paste.
• Aerosil®200 Degussa Corp., Richfield Park, NJ
• Plurafac D-25 Surfactant
• fragrance 1% by weight
• the aliphatic polyester urethane coatings tested in TABLE I were prepared according to ASTM D-609 protocol and were allowed to cure for 5 days. A portion of each coating was set aside in a dark container to serve as a control sample and the remaining samples were attached to the rotating test fixture of a standard weatherometer. The samples were continuously exposed to U.V. radiation. Each indicated test was performed in accordance with the ASTM protocol noted. All ASTM protocols referred to herein are 1990 protocols.
• the present invention may be used in many applications in addition to that of removal of graffiti as described hereinabove.
• the present invention may be employed successfully, for example, in applying a protective coating to walls in hospitals, industrial chemical treatment plants, food preparation areas, and the like. Chemical solvents, cleaners, and other defacing materials such as food, will not harm * the protective coating surface, and are easily removed with the cleaner means described.
• Reference herein to specific details of the graffiti-removal system is by way of example and not by way of limitation. It will be apparent to those skilled in the art that many modifications of the basic formulations and methods may be made without departing from the spirit and scope of the invention as recited by the claims.

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• Chemical & Material Sciences (AREA)
• Life Sciences & Earth Sciences (AREA)
• Engineering & Computer Science (AREA)
• Wood Science & Technology (AREA)
• Organic Chemistry (AREA)
• Materials Engineering (AREA)
• Chemical Kinetics & Catalysis (AREA)
• General Chemical & Material Sciences (AREA)
• Health & Medical Sciences (AREA)
• Medicinal Chemistry (AREA)
• Polymers & Plastics (AREA)
• Paints Or Removers (AREA)
• Application Of Or Painting With Fluid Materials (AREA)

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• 1993
  • 1993-04-30 EP EP93910936A patent/EP0640113A4/de not_active Withdrawn
  • 1993-04-30 CA CA002134780A patent/CA2134780C/en not_active Expired - Lifetime
  • 1993-04-30 WO PCT/US1993/004075 patent/WO1993022372A1/en not_active Application Discontinuation

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