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WO1998008619A1 - Procede servant a effectuer le revetement en fusion de surfaces au moyen de compositions polymeres durcissantes en poudre - Google Patents

Procede servant a effectuer le revetement en fusion de surfaces au moyen de compositions polymeres durcissantes en poudre Download PDF

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Publication number
WO1998008619A1
WO1998008619A1 PCT/US1997/014250 US9714250W WO9808619A1 WO 1998008619 A1 WO1998008619 A1 WO 1998008619A1 US 9714250 W US9714250 W US 9714250W WO 9808619 A1 WO9808619 A1 WO 9808619A1
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Prior art keywords
coating
substrate
temperature
curable
composition
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Ceased
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PCT/US1997/014250
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English (en)
Inventor
Faruq Marikar
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CNA Holdings LLC
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Hoechst Celanese Corp
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Priority to AU39152/97A priority Critical patent/AU3915297A/en
Publication of WO1998008619A1 publication Critical patent/WO1998008619A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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    • 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
    • B05D3/00—Pretreatment of surfaces to which liquids or other fluent materials are to be applied; After-treatment of applied coatings, e.g. intermediate treating of an applied coating preparatory to subsequent applications of liquids or other fluent materials
    • B05D3/06—Pretreatment of surfaces to which liquids or other fluent materials are to be applied; After-treatment of applied coatings, e.g. intermediate treating of an applied coating preparatory to subsequent applications of liquids or other fluent materials by exposure to radiation
    • B05D3/061—Pretreatment of surfaces to which liquids or other fluent materials are to be applied; After-treatment of applied coatings, e.g. intermediate treating of an applied coating preparatory to subsequent applications of liquids or other fluent materials by exposure to radiation using U.V.
    • B05D3/065—After-treatment
    • B05D3/067—Curing or cross-linking the coating
    • 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
    • B05D1/00—Processes for applying liquids or other fluent materials
    • B05D1/02—Processes for applying liquids or other fluent materials performed by spraying
    • B05D1/08—Flame spraying
    • B05D1/10—Applying particulate materials

Definitions

  • the present invention relates to methods of coating surfaces.
  • Polymeric powdered coating compositions such as certain paint compositions
  • are well-known [see, e.g., US Patent No. 5,470,912] and are used almost exclusively in industrial plants because their application requires large equipment, including conveyors, temperature controlled baking ovens and application booths.
  • acrylic clearcoat resins are usually applied on parts to be coated as a loose powder, after which the article is placed in a bake oven. These ovens bake the articles at temperatures between 100 °C and 200 °C for 20 to 30 minutes to melt the resin, eliminate bubbles and harden the resin by curing.
  • Some powdered coatings can be applied using flame guns, for example thermoplastic powders. [See, e.g., US Patent No.
  • thermocurable compositions can be applied directly with a hot gaseous stream which enables coating of heat-sensitive materials and provides a faster (e.g., one-step) coating process for metals and other materials.
  • the present invention provides a method of applying a meltable, powdered, thermocurable polymer composition to a surface in a substantially single application step.
  • the method involves providing a polymer composition to a hot gaseous stream in a spraying apparatus, in which the temperature and velocity of the gas stream are sufficient to melt the composition and maintain flowability thereof while the composition is in the gas stream.
  • the heated polymer composition is melt-sprayed onto the surface substantially simultaneously with entering the gas stream and, upon contact with the surface, is at least partially cured thereon.
  • substantial curing occurs in the absence of a subsequent curing, e.g., oven baking, step.
  • the method of the invention permits application of a meltable, powdered, radiation-curable polymer composition to a surface.
  • the method involves providing such a polymer composition to a hot gaseous stream in a spraying apparatus, in which the termperature and velocity of the gaseous stream are sufficient to melt the composition and maintain flowability thereof while the composition is in the gaseous stream.
  • the heated polymer composition is sprayed onto the surface substantially simultaneously with entering the gaseous stream and, upon contact with the surface, forms a substantially uniform liquefied film thereon.
  • liquid it is meant herein that the resin is at least partially melted.
  • the coated surface is subsequently exposed to ultraviolet radiation or an electron beam, which acts to substantially cure the polymer composition simultaneously with, or immediately subsequent to, said spraying.
  • the radiation is applied while the film is at least in a partially liquefied state.
  • Fig. 1 is an illustration of a spray gun suitable for use in the method of the invention.
  • the present invention includes a process for coating plastic material onto, for example, a flat sheet substrate such as rolled goods by way of introducing the powdered material into a hot gaseous stream, entraining the powdered material in the gas stream, the gas stream and material being heated to liquefy the powdered material, followed by directing the entrained liquefied, powdered material onto the substrate by directing the gas stream toward the substrate, coating the substrate with the material, and setting the material on the substrate as a solid phase adhered to the substrate.
  • Such coating onto rolled goods is sometimes referred to as coil coating.
  • the powdered material in general is a cross-linkable polymeric system which typically includes a polyester polymer, an epoxy polymer, a polyurethane polymer, an acrylic polymer or mixtures thereof.
  • the step of setting the material includes crosslinking the polymeric system substantially contemporaneously with the step of coating the substrate.
  • the method of the present invention provides for the application of powdered polymers, specifically meltable, powdered polymer compositions, including low molecular weight polymers, via a spray gun with substantially complete curing, without a separate curing/baking step.
  • This substantially one-step method provides important advantages for the coating or painting of a variety of substrates.
  • thermosettable polymer compositions include thermosetting paint polymers including, for example, polyester polymers, epoxy polymers, polyurethane polymers, acrylic polymers, and mixtures thereof.
  • Such resins are conventional crosslinkable or curable polymeric powder coating resin.
  • coating resins which may be used and are presently known to the art and include, but are not limited to: epoxy coating resins, polyester coating resins, acrylic coating resins and the like.
  • Conventional polymeric powder coatings may also include polyisocyanate crosslinked polyester coating resins, triglycidyl isocyanurate crosslinked polyester coating resins, polyester epoxy "hybrid”-type coating resins, triglycidyl isocyanurate crosslinked acrylic-type coating resins, polyisocyanate crosslinked acrylic-type coating resins, hydroxy alkylamine crosslinked polyester coating resins, hydroxy alkylamide crosslinked acrylic coating resins, amine crosslinked epoxy coating materials, anhydride crosslinked epoxy coating resins, tetramethoxymethyl glucoluril crosslinked acrylics or polyesters, and uretidione crosslinked polyester-type coating resins.
  • the resins may be either aromatic or aliphatic, as well as either blocked or unblocked materials, and for example, may include polyisocyanate-type materials blocked with caprolactam or methyl ethyl ketoxime.
  • composition of this invention may also include various other constituents which are used in polymeric powder coating compositions.
  • Further constituents which may be useful in the improved polymer coating compositions according to the present invention include catalyzing agents, flow control agents, coloring agents such as pigments or dyes, fillers, processing aids such as silica, catalysts, matting agents, and other conventional processing aids and additives known to those of ordinary skill in the art.
  • Suitable pigments include, without limitation, carbon black, ultra marine blue, dyes based on phthalocyanine, titanium dioxide, cadmium sulfide, cadmium sulfide selenide, nigrosine and the like.
  • Such conventional catalysts include, but are not limited to, stannous octoate, dibutyl tin dilaureate, dibutyl tin diacetate and the like.
  • Conventional materials which are used to control the surface appearance of the polymeric coating include matting agents which limit the surface gloss.
  • Such matting agent materials include waxes, silicas, polytetrafluoroethylene, as well as other conventional materials not particularly denoted here.
  • Processing aids which improve the process ability, and in the formation of the polymeric coating may be included in the compositions.
  • silica or benzoin are known to the art as processing aids.
  • the amounts of the above-identified conventional additives to the polymer compositions can be amounts which are conventional for such compositions.
  • the selection and amounts of such agents are well within the skill of this art and do not limit this invention.
  • thermocurable polymer compositions for use in the method of the invention may be readily selected by one of skill in the art. When the powdered polymer is applied in a molten condition according to this invention, it adheres to any surface and it is not necessary that the composition be electrostatic or tribochargeable.
  • a particularly suitable polymer composition is defined herein as a thermocurable composition containing at least one base resin and either a second cross-linking base resin or a cross-linking agent.
  • the polymer composition may have a base resin selected from among carboxy-terminated polyester resins, hydroxyl-functional polyester resins, and glycidyl-functional acrylic resins.
  • the cross-linking agent is a caprolactam- blocked isophorone diisocyanate crosslinker.
  • the composition may contain a second base resin such as a bisphenol A/epichlorohydrin epoxy resin.
  • Suitable UV-curable powder coating materials including epoxy acrylates, urethane acrylates, polyester acrylates, unsaturated polyesters, diluted with styrene or with low-viscosity acrylates are likewise commercially available.
  • Other suitable polymers for use in the method of the invention may be readily selected by one of skill in the art. See, also,
  • the photocurable or radiation curable compositions useful in this invention may also include various other constituents, which may be selected by one of skill in the art as noted above.
  • Typical monomers used in this way are hexane diol diacrylate and trimethylol propane triacrylate. These monomers may be dissolved in one or more di- or polyfunctional acrylic monomers. This gives a system that, when dosed with a suitable photo initiator, may be converted at room temperature to hard, flexible, chemical-resistant films.
  • Photo initiators are materials such as the aromatic ketone benzophenone.
  • the molecule dissociates to provide a source of free radicals on exposure to high intensity ultraviolet radiation (usually 325-365 nanometers).
  • Polymerization takes place via acrylic unsaturation and involves groups on both the prepolymer and the multifunctional monomers used as solvents.
  • Mono-functional monomers may also be added. They are lower in viscosity than are the multi-functional monomers. In controlled quantities, mono-functional monomers are useful for viscosity adjustment and control of cross link density.
  • the acrylics are somewhat more reactive to ultraviolet light than are the methacrylics, which are, in turn, more reactive than the allyl and vinyl type monomers.
  • Prepolymers are not confined to the urethane acrylics; epoxy acrylics are also available. These prepolymers are formed by the reaction of the oxirane linkages of low molecular weight bisphenol A resins with acrylic acid. Polyester acrylic prepolymers (prepared via the reaction of acrylic acid and hydroxy functional polyether and polyester resins) have also been employed in this way. In all of these systems, careful inhibition of the acrylic (at both the prepolymer stage and in the final coating) is vital to prevent unwanted polymerization. In general, compositions useful in connection with the present invention exhibit melting temperatures, that is become liquid at temperatures of 100°C or less. The gas temperature of the hot gaseous stream is thus typically 200°C or thereabouts as described below.
  • a conventional meltable, thermocurable polymer powder is introduced into a spraying device, such as a flame gun, plasma gun, hot air gun or hot gas gun.
  • the spraying device is not critical so long as it is capable of melt-spraying the liquefied or powdered polymer to a surface via use of a hot gaseous stream.
  • a hot air gun may be preferred.
  • the gaseous stream is desirably at a temperature at least twice that of the melting temperature of the polymer composition in degrees Celsius (°C) .
  • the temperature of the stream is between about 100°C to about 600°C.
  • the velocity of the hot gas stream is such that it propels the polymer composition onto the desired surface or substrate.
  • the conditions of temperature and velocity in the hot gas stream are sufficient to melt the polymer composition and maintain its flowability while the polymer is in the stream.
  • the heated polymer composition is sprayed onto any desired surface or substrate substantially simultaneously with entering the gas stream.
  • the surface is exposed to the spraying source for between about 0.1 to about 120 seconds, and more preferably between about 10 - 100 seconds.
  • the distance between the spraying apparatus and the surface is maintained at from about 1 to about 25 cm, and preferably from about 1 to about 10 cm.
  • the exposure time and distance between the spraying source and the coated surface may be readily adjusted by one of skill in the art.
  • the gas stream heats the polymer composition such that upon contact with the surface, the polymer composition is at least partially cross-iinked or cured so that it exhibits a glass transition temperature or melting temperature in degrees Celsius which is at least two times the melting temperature of the base resin forming the major component of the polymer composition.
  • This causes the melted material to fuse and form a continuous polymeric coating on the surface.
  • the curing (or partial curing) occurs in the absence of further heating and as a result of the heating effect of the hot gas stream on the polymer composition.
  • coatings applied according to the method of the invention do not require oven curing.
  • the surface on which the powdered polymer composition is melt-sprayed with the gun may be preheated and the composition cured during or after said application.
  • the surface spray coated by the method of the invention may be subsequently subjected to infrared (IR) rays to heat the coating.
  • IR infrared
  • This step may substitute for the use of a dryer, or be used in conjunction therewith.
  • Suitable IR-beamers are commercially available.
  • medium wave IR rays are preferred, which heat the substrate more quickly.
  • the substrate is exposed to the IR radiation source for between about 0 to about 1 20 seconds after being coated with the composition, and more preferably between about 10 - 100 seconds.
  • the distance between the IR source and the surface is maintained at about 1 to about 24 cm.
  • this radiation step may be performed while the film coating is still hot.
  • This separate drying step may be the only drying step applied to the coated surface, or it may be used to achieve further hardening of the polymer coating partially cured following coating by the method of the invention.
  • the Substrate Material Substrates specifically contemplated within the present invention include substrates such as polymer film or sheet substrates. Other substrates are further contemplated as hereinafter described. D. The Spraying Apparatus
  • Suitable spray guns for use in this invention may be readily adapted from among the flame, plasma combustion (inert or spiked), high velocity oxygen fuel (hot air) and detonation guns known in the art.
  • suitable spray guns are commercially available from
  • Plastic Flamecoat ® Systems Big Spring, TX
  • Alamo Supply Company, Inc. Houston, TX
  • UTP Welding Materials, Inc. Houston, TX
  • These commercial flame spray guns may be readily modified for use in the method of the invention by lowering the flame temperature to meet the requirements of the present invention, i.e., to provide a gaseous stream at a suitable temperature range, that allows the polymer to be applied in powdered or liquefied form.
  • the gaseous stream may be at a temperature about twice that of the melting temperature of the polymer in degrees Celsius (°C), or between about 100°C to about 600°C so that the polymer can be applied in liquified form.
  • Fig. 1 provides a schematic of a suitable spray system.
  • a suitable spray gun for use in the method of the invention permits the powdered polymer to be projected in powder (or liquefied) form from an adjustable close distance and to be deposited on a surface in a molten or powdered condition.
  • a spray gun of the invention is preferably a hot air generator or convector capable of delivering hot air with variable temperature and output.
  • Preferred velocity of the gaseous stream can be between about 30 to about 3000 mph, and preferably between 60 to 600 mph.
  • Feed rates of the polymer composition into and through the spray gun can be typically about 1 to about 60 lbs/hour, depending on nozzle size and gas velocity.
  • Such a gun may further have a separate or combined spray and dryer nozzle so that the spray and drying features may be used contemporaneously or alternately as desired.
  • the distance from the output nozzle of the gun from the substrate may be between about 1 to about 40 cm.
  • these features are combined, permitting simultaneous spraying of the heated polymer composition onto the surface so that, upon contact with the surface, the polymer composition is at least partially cured. This curing takes place to a glass transition temperature or melting temperature (°C) which is at least two times that of the base resin which forms the composition.
  • the equipment used in the method of the invention has a reduced size and thus greater flexibility, e.g., it may be a single unit or a set of units, movable or fixed.
  • the method of the invention allows the coating of static or large surfaces, or small surfaces even for retouching purposes, by applying the paint or other coating materials melted at a temperature lower than that required for cross-linking.
  • the VSC 146 is a glycidyl-functional acrylic resin containing methacrylic acid, acrylic acid and ethyl acrylate as major components with alkyl oligoethylene glycol crotonate as a minor component.
  • the VXL 1 381 is an anhydride hardener which is dodecaryl, dicarboxylic acid anhydride.
  • the Additol7 LH 627 product is a flow control agent.
  • This formulation was mixed, extruded at a temperature of between 1 1 5°C to 120°C from a twin screw extruder and the extrudate was ground to powder.
  • the melting point of this composition is about 74°C.
  • the powder polymer composition prepared as described above was injected into a spray gun and entrained in hot air at a temperature of approximately 240°C.
  • the composition was thermally sprayed from a spray gun nozzle about 3-4 inches from the steel, wood, polycarbonate plastic sheet and ABS plastic sheet substrates.
  • the powder was also thermally sprayed on "plaster board" used in construction of walls of buildings for about 60 seconds. The distance of the end of the gun from the substrate surface was about 3.75 inches.
  • the melt-sprayed coating according to the present invention had a 53 micron thickness on steel and when tested, had less than 80 inch lb mechanical resistance in direct and reverse impact testing.
  • the chemical resistance was less than 100 MEK double rubs [The Powder Coating Institute, #8 Recommended Procedure for Solvent Cure Test] and the pencil hardness was 2B [ASTM Designation D3363-74 (Reapproved 1 989) Standard Test Method for Film Hardness by Pencil Test].
  • a 6" x 3" "Q" coupon was sprayed with the acrylic clearcoat powder prepared as described in A above using hot air as described above and subsequently heated with 490°C hot air for 7 seconds.
  • the coating of 48 microns thickness had greater than 1 60 inch-lb mechanical resistance in direct and reverse impact testing and pencil hardness of H; chemical resistance was better than 100 MEK double rubs.
  • This acrylic clearcoat was thus cured without baking in an oven. The cured coating was smooth and glossy.
  • Example 2 Thermal Spray Coating of Hybrid Po yester-Epoxy Paint The following experiment made use of a polymer composition having a melting point of about 60°C containing the components listed in Table II.
  • the Alftalat ® AN 783 product is a carboxy-terminated (saturated carboxylated) polyester resin, the major constituents being terephthalic acid and neopentyl glycol and minor constituents being adipic acid, ethylene glycol and trimethylol propane.
  • Epon ® 2002 epoxy resin is a bisphenol A/epichlorohydrin, epoxy resin.
  • Additol ® XL 496 product is a hydroxylate polyester resin for flow control. The above composition is likewise suitable for application as described in connection with example 1 .
  • a polyester-polyurethane resin having a melting point of about 63°C was formulated of the following components in Table III: Table III
  • the AN 745 product is a hydroxyl functional polyester resin with major constituents being terephthalic acid and neopentyl glycol and with minor constituents being adipic acid, isophthalic acid and trimethylol propane.
  • the Vestagon ® B1530 product is a capprolactan- blocked isophorone diisocyanate crosslinking agent.
  • the Additol product is as described above in Example 2.
  • the formulations were melt gravided in a twin-screw extruder and the extrudate was powdered.
  • the powder was thermally sprayed, according to this invention, 8" x 4" polycarbonate and ABS plastic plates from a nozzle to substrate distance of about 2.5 inches.
  • the air temperature in the spray gun was 240°C and the temperature of the plastic material rose to 40°C.
  • the coatings were partially cross-linked (cured) upon contact with the coupons and plates.
  • the metal plates were subsequently heated with 460°C air for one minute to fully cross-link the resins.
  • the temperature of the back of the plates was 140°C to 1 50°C.
  • Example 4 Thermal Spraying of UV-Cure Clearcoat Composition A. Preparation of UV Clearcoat
  • a UV-curable formulation of the following composition of Table I was prepared.
  • the Alftalat ® resin is an unsaturated polyester the major components of which are terephthalic acid, neopentyl glycol, and maleic anhydride.
  • the Additol7 product is a polyurethane acrylate containing hydroxypropyl acrylate, isophorone diisocyanate, and 2-ethyl 2- hydroxymethyl 1 ,3 propanediol.
  • the formulation having a melting point of about 82-93°C was thermally sprayed on wood by injection into hot air of temperature 170°C, 200°C, 220°C, 245°C, 295°C and 370°C.
  • the powder was also thermally sprayed with 245°C hot air on metal (steel), polycarbonate and ABS plastic. In each case, the distance between the nozzle of the spray gun and the substrate surface was about two inches.
  • the coatings sprayed on wood at hot air temperatures of 245°C, 295°C and 370°C were UV cured by passing under a UV beamer (IST-Strahlentechnik Metz)-200-U CK with 80 W/cm, emission maximum 360 nm, with two passes.
  • the UV cure was performed with and without preheating for 30 seconds using a Medium wave IR-beamer Heraeus MMS 2000/32 kw/m 2 at 25 cm distance for 30 seconds. Subsequent testing of the coated wood panels of 8" x 3 1 /2" revealed high degree of cross linking with little or no change on exposure to butyl acetate for 3 minutes and xylene for 30 minutes, for both IR-heated and non-heated samples.
  • the present invention is directed to a method of providing a cured coating to an architectural substrate such as a bridge, building, house, free standing structure, walkways, objects or the like.
  • the process steps are to entrain a powder composition into a hot gaseous stream, with a gas temperature sufficient to melt said powder composition to form a liquefied material followed by applying the stream to the substrate to form a liquefied, that is, at least partially melted, coating thereon.
  • the liquefied coating is then cured, either by way of the application of radiation, in the case of radiation-curable powder compositions, or the coating is self-curing in the case of the thermocurable powder compositions.
  • curable resins used in accordance with the present invention are cured by way of cross-linking as described further herein.
  • curable refers to a crosslinkable material and the terms "melted”, “liquid”, or “liquefied” mean at least partially melted to a liquid state unless the text explicitly indicates otherwise.
  • the present invention has numerous advantages not before realized in connection with powder coatings. For one aspect, it is noted below, that it is possible to deposit thinner, uniform films due to the "splatting" effect. As used herein a substantially uniform film of a given thickness is one that is between 50% and 200% of that thickness throughout. It is possible to apply substantially uniform thin films with the present invention, say less than 50 microns in thickness with films of 10-40 microns being preferred; but perhaps more pertinent to the substrates contemplated herein, it is also possible to build thicker coatings, either substantially uniform or otherwise of 50-
  • the hot gas stream having an average temperature at least twice the melting point of the powder composition, e.g. 1 50°C to 300°C, the liquefied powder splatters on the application surface to form a substantially uniform coating as noted above, and this leads to further advantages.
  • powder resin compositions there is more flexibility in selecting powder resin compositions.
  • Higher molecular weight, typically tougher and more durable resins may be selected if so desired since their higher viscosity is not as much as a limitation in forming a uniform film, as it is when one merely relies on the formation of the film by liquefaction of the powder coating in an oven.
  • Higher molecular weight coatings, besides having enhanced toughness are typically more durable and have more corrosion resistance.
  • Still another advantage of the method of the present invention is that the melt-application method minimizes the need for the surface preparation since the high velocity application method promotes adhesion.
  • a rusted metal surface could be coated without sand blasting, or a road surface could be minimally prepared.
  • the present invention may be particularly useful where lead paint abatement (containment) is a problem since it is possible to simply coat the surface to contain the leaded paint.
  • the method is relatively weather-insensitive and may be used under moist conditions.
  • the present invention may also be used in connection with virtually any roadway surface to be provided with highway markings, whether it is asphalt, concrete, or even a wooden, brick or steel surface as may be found on a bridge.
  • Advantages of the present invention include the fact that the method is relatively weather- insensitive, particularly to moisture or temperature which are often problems with conventional paint application means; as well as the fact the present invention requires virtually no curing time.
  • the present invention is directed to a method of providing a thin film cured powder coating to a substrate.
  • the process steps are to entrain a powder composition into a hot gaseous stream, with a gas temperature sufficient to melt powder composition to form a liquid material followed by applying the stream to the substrate to form a liquefied, that is at least partially melted, coating thereon.
  • the liquefied coating is then cured, either by way of the application of radiation, in the case of radiation-curable powder compositions, or the coating is self-curing in the case of the thermocurable powder compositions.
  • the curable resins used in accordance with the present invention are cured by way of cross- linking as described further herein.
  • the term curable refers to a crosslinkable polymeric system and the terms "melted”, “liquid” or “liquefied” mean at least partially melted to the liquid state unless the text explicitly indicates otherwise.
  • powder coating formulations have in their unmelted state particles of approximately 20 microns or more in average diameter. It is thus extremely difficult to produce uniform coatings having thicknesses of 50 microns or less by conventional powder coating means.
  • the high velocities, melting of the powder formulations prior to impact with the substrate and so on introduce substantial flattening of the particles so it is possible to produce substantially uniform films of 50 microns or less; such as 40 microns or less, 25 micron or even 10 micron substantially uniform films.
  • the application phenomenon sometimes referred to as splatting, in connection with thermoplastic powder coatings, conserves material and also minimizes the need for surface preparation, promotes adhesion, and allows for the application of relatively high molecular weight, relatively tough, powder compositions.
  • the present invention is likewise suitable as a method of providing a cured coating to a temperature sensitive substrate.
  • the process steps are to entrain a powder composition into a hot gaseous stream, with a gas temperature sufficient to melt powder composition to form a liquid material followed by applying the stream to the substrate to form a liquefied, that is at least partially melted, coating thereon.
  • the liquefied coating is then cured, either by way of the application of radiation, in the case of radiation-curable powder compositions, or the coating is self-curing in the case of the thermocurable powder compositions.
  • the curable resins used in accordance with the present invention are cured by way of cross- linking in any event as described further herein.
  • the term curable as used herein refers to a crosslinkable material and the terms "melted", “liquid”, or “liquefied” mean at least partially melted to a liquid state unless the text explicitly indicates otherwise.
  • the temperature-sensitive substrates specifically contemplated within the present invention include wooden substrates such as furniture and the like or polymer substrates.
  • Wooden substrates may include hardwoods incorporated as part of a piece of furniture such as maple substrates, oak substrates and the like as well as veneered substrates which are generally wood/adhesive composite structures including plywood as well as decorative veneered articles.
  • veneered substrates which are generally wood/adhesive composite structures including plywood as well as decorative veneered articles.
  • linear polyesters which may be employed as a thermoplastic substrate in the form of film or sheet in practicing the present invention include polyesters of alkyl glycols and aromatic acids such as: poly(alkylene terephthalates) having the repeating unit
  • terepolymers and linear polyesters with even more monomers.
  • Particularly desirable terepolymers might include poly(alkylene terephthalate-co-4,4'-bibenzoate), and poly(alkylene 4,4'-bibenzoate- co-2,6-naphthalene dicarboxylates) . These polymers are disclosed in United States Patent Nos. 3,008,934, 4,082,731 and 5,453,321 as well as European Application No. 0 202 631 .
  • thermoplastic polymers such as polyolefins, polyurethanes, pol ⁇ acetals and so on would be similarly extensive yet not exhaustive.
  • elastomers may be thermosetting or thermoplastic and include natural rubber based materials.
  • Thermoplastic elastomers which may be suitable as substrate components include block copolymers as noted in Table A below. TABLE A. THERMOPLASTIC BLOCK COPOLYMERS
  • the three commercially important elastomer block copolymers are poly(styrene-elastomer-styrene), thermoplastic polyurethanes, and thermoplastic polyesters. Particularly preferred commercially available block copolymer thermoplastic elastomers appear in Table B below.
  • Riteflex is a multiblock (A-B)n type elastomer wherein, A the hard segment is poly(butylene terephthalate) and B, the soft segment is poly(tetrameth ⁇ lene ether); note that n denotes an integer.

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Abstract

Procédé servant à appliquer une composition polymère durcissante de revêtement en poudre à un substrat en pratiquement une seule étape. Cette composition contient au moins une résine de base et une deuxième résine de base de réticulation ou un autre agent de réticulation. Dans un mode de réalisation, ce procédé consiste à appliquer cette composition sous forme d'écoulement chaud gazeux dans un appareil de pulvérisation. La température de l'écoulement gazeux est telle que la composition polymère durcit lorsqu'elle vient en contact avec la surface en l'absence d'un nouveau réchauffement important. En général, les résines sont durcies soit au moyen de l'écoulement chaud gazeux, soit par application d'un rayonnement.
PCT/US1997/014250 1996-08-30 1997-08-11 Procede servant a effectuer le revetement en fusion de surfaces au moyen de compositions polymeres durcissantes en poudre Ceased WO1998008619A1 (fr)

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AU39152/97A AU3915297A (en) 1996-08-30 1997-08-11 Method for melt-coating surfaces with curable powder polymer compositions

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US70642396A 1996-08-30 1996-08-30
US70489096A 1996-08-30 1996-08-30
US70642496A 1996-08-30 1996-08-30
US08/706,424 1996-08-30
US08/704,890 1996-08-30
US08/706,423 1996-08-30
US77929297A 1997-01-06 1997-01-06
US77929397A 1997-01-06 1997-01-06
US77898497A 1997-01-06 1997-01-06
US77898797A 1997-01-06 1997-01-06
US77898697A 1997-01-06 1997-01-06
US77898597A 1997-01-06 1997-01-06
US77929997A 1997-01-06 1997-01-06
US08/778,987 1997-01-06
US08/778,984 1997-01-06
US08/778,985 1997-01-06
US08/779,299 1997-01-06
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Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1999036190A1 (fr) * 1998-01-20 1999-07-22 Ford Global Technologies, Inc. Procede de depot de dielectrique sur des elements electroconducteurs
EP0984073A3 (fr) * 1998-08-31 2000-04-05 Ford Global Technologies, Inc. Méthode et utilisation de masques de pulvérisation thermique portant un revêtement d'epoxy thermoduricissable
GB2353739A (en) * 1999-09-04 2001-03-07 Federal Mogul Technology Ltd Applying a low friction and low wear coating
WO2001085363A1 (fr) * 2000-05-08 2001-11-15 Advanced Photonics Technologies Ag Procede et dispositif de production d"une structure en couches mince
WO2001089718A3 (fr) * 2000-05-23 2002-04-25 Cesare Montesano Procede et appareil d'application d'une peinture photopolymerisable solide sur des surfaces plates de produits, et produit ainsi obtenu

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FR700227A (fr) * 1929-08-10 1931-02-26 Thomson Houston Comp Francaise Procédé de revêtement des corps et produits industriels nouveaux résultant de son application
FR918147A (fr) * 1941-07-16 1947-01-30 Ici Ltd Application de revêtements protecteurs sur des surfaces
CH269269A (de) * 1948-06-03 1950-06-30 Andre Dr Schaerer Verfahren zur Herstellung festhaftender homogener Überzüge aus hochmolekularen Stoffen auf Metallen, Mauerwerk, Papier und andern Unterlagen.
FR1203298A (fr) * 1957-09-19 1960-01-18 Ruhrchemie Ag Revêtements en polyéthylène chloré sur des supports en métal, textiles ou papier
GB1122564A (en) * 1964-09-15 1968-08-07 Berk Ltd Flame spraying
DE2106466A1 (en) * 1971-02-11 1972-08-31 Metallgesellschaft AG, 6000 Frank fürt Polyolefin foam layers or strips - from mixt contg propellant and opt cross-linking agent sprayed on with flame gun
US3962486A (en) * 1974-01-02 1976-06-08 Eppco Novel process for applying thermoset resinous coatings
GB1545611A (en) * 1976-01-02 1979-05-10 Kearns Tribune Corp Coated container apparatus and process for coating same
US4985278A (en) * 1989-07-17 1991-01-15 Shell Oil Company Coating process

Patent Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR700227A (fr) * 1929-08-10 1931-02-26 Thomson Houston Comp Francaise Procédé de revêtement des corps et produits industriels nouveaux résultant de son application
FR918147A (fr) * 1941-07-16 1947-01-30 Ici Ltd Application de revêtements protecteurs sur des surfaces
CH269269A (de) * 1948-06-03 1950-06-30 Andre Dr Schaerer Verfahren zur Herstellung festhaftender homogener Überzüge aus hochmolekularen Stoffen auf Metallen, Mauerwerk, Papier und andern Unterlagen.
FR1203298A (fr) * 1957-09-19 1960-01-18 Ruhrchemie Ag Revêtements en polyéthylène chloré sur des supports en métal, textiles ou papier
GB1122564A (en) * 1964-09-15 1968-08-07 Berk Ltd Flame spraying
DE2106466A1 (en) * 1971-02-11 1972-08-31 Metallgesellschaft AG, 6000 Frank fürt Polyolefin foam layers or strips - from mixt contg propellant and opt cross-linking agent sprayed on with flame gun
US3962486A (en) * 1974-01-02 1976-06-08 Eppco Novel process for applying thermoset resinous coatings
GB1545611A (en) * 1976-01-02 1979-05-10 Kearns Tribune Corp Coated container apparatus and process for coating same
US4985278A (en) * 1989-07-17 1991-01-15 Shell Oil Company Coating process

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1999036190A1 (fr) * 1998-01-20 1999-07-22 Ford Global Technologies, Inc. Procede de depot de dielectrique sur des elements electroconducteurs
EP0984073A3 (fr) * 1998-08-31 2000-04-05 Ford Global Technologies, Inc. Méthode et utilisation de masques de pulvérisation thermique portant un revêtement d'epoxy thermoduricissable
GB2353739A (en) * 1999-09-04 2001-03-07 Federal Mogul Technology Ltd Applying a low friction and low wear coating
WO2001085363A1 (fr) * 2000-05-08 2001-11-15 Advanced Photonics Technologies Ag Procede et dispositif de production d"une structure en couches mince
WO2001089718A3 (fr) * 2000-05-23 2002-04-25 Cesare Montesano Procede et appareil d'application d'une peinture photopolymerisable solide sur des surfaces plates de produits, et produit ainsi obtenu

Also Published As

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