Spring 2002 Vol. 4, No. 1

U.S. Patents

Method and Apparatus for Electrostatic Powder Coating
U.S. Patent 6,202,945
Issued: March 20, 2001
Inventors: Yasuda, Shinichiro, et al
Assigned to: Kao Corp.

While various types of powder paints of different hues are mixed with each other without melting for preparation of a powder paint of a desired hue, a fluidity improver possessing a charge control function is simultaneously mixed into the powder paints without melting. The mixed powder paint containing fluidity improver is charged, and then electrostatic powder coating is performed by the charged powder paint. The fluidity improver also acts as a charge control agent, which allows the powder mixture to be electrostatically sprayed without significant separation of the various powders. Suitable fluidity improvers include silica, aluminum oxide, titanium dioxide, various titanates and other fine particle size inorganics. Also described is the apparatus for mixing the fluidity improvers with the powder mixture and stabilizing the electrostatic charges on the particles.

Combining Differently Colored Powder Coatings That Heat-Cure to Homogeneous Hue
U.S. Patent 6,207,768
Issued: March 27, 2001
Inventors: Sato, Yukiya, et al
Assigned to: Kao Corp.

A powder coating composition comprising two or more different-colored powder coatings that are heat-cured and fuse with each other to thereby create a coating film having a homogeneous hue. A coating method comprising the steps of (a) applying to a substrate two or more powder coatings, of which each color is different; (b) heating to fuse with each other each of the two or more powder coatings applied in step (a); and (c) curing the resulting fused product in step (b), to provide a coating film having a homogeneous hue.

Method of Powder Coating
U.S. Patent 6,214,421
Issued: April 10, 2001
Inventor: Pidzarko, Dennis
Assigned to: Inventor

A method of powder coating at least one surface of a nonconductive object having a plurality of sequential steps. The first step is pretreating the surface of the nonconductive object to ensure that the surface is suitably cleaned. The second step is to apply a sufficient quantity of moisture on the surface of the nonconductive object to facilitate adhesion of a powder coating to the surface. The next step is to spray a polymer coating powder on the moistened surface of the nonconductive object. This spraying step is done immediately following the application of moisture but prior to a complete evaporation of applied moisture. The next step is to evaporate any remaining applied moisture from the nonconductive object prior to curing. The last step is to cure the coating on the surface of the nonconductive object without decomposing the powder and then either cool or allow the non-conductive object to cool naturally.

Modified Polyester Resin/Organic Peroxide Systems for Powder Coatings
That Are Applicable to Temperature-Sensitive and Metallic Substrates.
U.S. Patent 6,214,898
Issued: April 10, 2001
Inventors: Diloy, Barrio Jose Luis
Assigned to: Herberts Gesellschaft mit beschrankter Haftung

New modified polyester resin/organic peroxide systems for powder coatings that are applicable to temperature-sensitive and metallic substrates include (a) a polyester resin that is a hydroxylated or carboxylated polyester with unsaturation in its chain and (b) an organic peroxide with a minimum curing temperature of between 140 and 190°C.; the relative proportions of resin and organic peroxides being 55 to 60% by weight of resin based on the final composition; and 0.5 to 3.0% by weight of organic peroxide based on the final formulation. These systems find their main application in the manufacture of powder coatings for the coating of temperature-sensitive substrates like plastics and metallic substrates, especially aluminum substrates, using the systems currently existing in industry.

Epoxy Resin, Process for Preparing the Resin and Photo-Curable Resin Composition and Resin Composition for Powder Coatings Containing the Epoxy Resin.
U.S. Patent 6,218,482
Issued: April 17, 2001
Inventors: Yamanaka, Masahiko, et al
Assigned to: New Japan Chemical Co., Ltd.

Claimed is an epoxy resin of specified composition, its preparation, and photo-curable powder coating resin compositions containing it.

Powder Coating of Epoxy Resin, Imidzaole-Epoxy Resin Catalyst or Polyamine, Polyamine Powder and Amine Scavenger
U.S. Patent 6,218,483
Issued: April 17, 2001
Inventors: Muthiah, Jeno, et al
Assigned to: Rohm and Haas Co.

Heat-sensitive substrates as well as others, such as metal or glass, are electrostatically coated with a thermosetting coating powder comprising a melt-mixed, chilled, chipped and powdered blend of an epoxy resin and a catalyst therefore, and a polyamine as a powdered low-temperature curing agent along with a scavenger which will react secondarily with residual polyamine domains that do not contact the base epoxy resin during curing. The coating powder is deposited on the substrate and heated to fuse, flow and cure. The mixture of resin and catalyst does not cure within the extruder but it is made to cure at low temperatures on the desired substrate by the separate addition of the curing agent to the powdered melt-mixed blend.

Fluorinated Powder Coatings Having Improved Gloss
U.S. Patent 6,221,429
Issued: April 24, 2001
Inventors: Verwey, Edwin, et al
Assigned to: Fina Research, S.A.

Pigmented powder coating products based on low melting point fluorine-based terpolymers, preferably on those made from a majority of vinylidene fluoride copolymerized with tetrafluoroethylene and hexafluoropropene, are capable of providing coatings with controllable gloss properties. The process for preparing coatings from the powder is essentially characterized by the selection of the temperature at which the desired gloss can be obtained, from low to high, without degradation of the mechanical properties.

Continuous Processing of Powder Coating Compositions
U.S. Patent 6,228,897
Issued: May 8, 2001
Inventors: Daly, Andrew T., et al
Assigned to: Rohm and Haas Co.

Systems, apparatus combinations and methods for producing a powder coating are provided wherein a stream of a powder coating precursor including at least one resin and at least one additional powder coating ingredient is contacted with a process fluid effective to reduce the viscosity of the powder coating precursor to allow processing of the powder coating precursor at a lower
temperature.

Powder Coating Composition
U.S. Patent 6,228,927
Issued: May 8, 2001
Inventors: Lucarelli, Michael A., et al
Assigned to: Cabot Corp.

A composition suitable for use in a
powder coating process comprising a powdered polymer composition and a metal oxide-based fluidization enhancer, or a metal oxide-based flatting agent. The metal oxide is blended with the powdered polymer during the grinding operation or after the powder has been ground. Superior improvements in fluidization efficiency are obtained if the metal oxide is comminuted to reduce the size of agglomerates. If the metal oxide is treated with hexamethyldisilazine and the ammonia generated during the reaction is not volatilized, a significant gloss reduction of the coating powder is observed after it has been applied to a substrate and cured.

Powder Coating of Glycidyl-Functional Copolymer, Dicarboxylic Acid and Acid-Functional Polyester
U.S. Patent 6,228,941
Issued: May 8, 2001
Inventors: DeCock, Christian Jean Charles, et al
Assigned to: Shell Oil Co.

A powder coating composition suitable for use as an automotive clearcoat is prepared from a glycidyl functional copolymer, acid functional polyester and a linear dicarboxylic acid. The coating powder has good shelf stability (does not sinter), good application characteristics and can be cured at a low temperature (120 to 140ºC).

Process for Preparing an Aqueous Dispersion Coating Material and Process for Preparing a Powder Coating Material
U.S. Patent 6,228,981
Issued: May 8, 2001
Inventors: Okazaki, Haruhiko, et al
Assigned to: Dai Nippon Toryo Co. Ltd.

A process for preparing an aqueous dispersion coating material containing a resin component having a softening temperature of from 10 to 250°C, which comprises: (1) a step of mixing various starting materials which will be coating film-constituting components to obtain a blend material; (2) a step of melting and kneading the blend material at a temperature of at least the softening temperature of said resin component to obtain a homogenized material; (3) a step of cooling and solidifying the homogenized material, followed by crushing to obtain coarse particles; and (4) a step of wet-pulverizing the coarse particles in an aqueous dispersant to obtain an aqueous dispersion coating material containing fine particles having an average particle size of no more than 10 microns.

Method for On-Mold Coating Molded Articles With a Coating Powder as a Liquid Gel Coat Replacement
U.S. Patent 6,235,228
Issued: May 22, 2001
Inventors: Nicholl, Edward G., et al
Assigned to: Morton International Inc.

Method for on-mold surface coating fiberglass-reinforced molded articles during their manufacture with environmentally friendly and physiologically safe thermosetting unsaturated polyester on-mold coating powders that serve as replacements for liquid gel coats. The thermosetting coating powders employed are adapted to cure at low temperatures to avoid causing thermal damage to the heat-sensitive plastic molds that must be reused over and over again, and to cure in the presence of atmospheric oxygen to enable over coating with liquid fill resins and fiberglass, which constitute the bulk of the finished article, without having the fill resins bleed through the powder coating film and detrimentally affect the overall quality of the surface finish.

Powder Coating Involving Compression of the Coating During Curing
U.S. Patent 6,238,750
Issued: May 29, 2001
Inventors: Correll, Glenn D., et al
Assigned to: Rohm and Haas Co.

A process of forming coatings on substrates by applying a layer of curable materials in dry powder form and then melting and curing the material is improved by compressing the layer using a flexible membrane. Less material is required to provide equivalent barrier protection and surface finish. The process is particularly applicable to applying dry powder coatings on temperature-sensitive substrates, such as medium density fiberboard, in press apparatus, such as a membrane press, which have not commercially used dry powder coating materials previously.

Powder Coating Composition
U.S. Patent 6,239,215
Issued: May 29, 2001
Inventors: Morita, Hirokazu, et al
Assigned to: Takeda Chemical Industries Ltd.

A powder coating composition comprising a multilayer polymer particle in which at least one inner layer is a polymer layer having a glass transition temperature (Tg) of not over 20°C and the outermost layer is a polymer layer having a Tg of not less than 60°C. The multilayered polymer particle is dispersed in an amount of 1 to 30 parts by weight per 100 parts by weight of the total monomeric components other than the multilayer polymer particle. It shows excellent dispersibility with various powder coatings and can improve workability and impact resistance of the coating while maintaining inherent characteristics such as appearance and blocking resistance.

Powder Coating Prepared From PET Resin Products as Raw Material and Process for the Preparation Thereof
U.S. Patent 6,239,234
Issued: May 29, 2001
Inventors: Tsubuki, Yukihisa
Assigned to: K. K. Seishin Kigyo

A composition for powder coating that comprises a melt blend of 100 weight parts of PET resin pellets or small pieces obtained from recovered PET resin molded products with 5-40 weight parts of a polyester resin (excluding PET) or a modified polyester resin, 3-30 weight parts of modified polyolefin resin or ethylene acrylic acid copolymer resin, or 3-30 weight parts of polycarbonate resin, the powder material exhibiting an improved ability to adhere to metal surfaces.

Triboelectric Chargeable Coating Powder
U.S. Patent 6,242,052
Issued: June 5, 2001
Inventors: Hilger, Christoph, et al
Assigned to: BASF Coatings AG

The present invention relates to triboelectrically chargeable powder coating materials to which benzimidazole-based additives are added.

Powder Coating Compositions Containing Transfer Efficiency-Enhancing Additives
U.S. Patent 6,245,839
Issued: June 12, 2001
Inventors: Jolley, Scott T., et al
Assigned to: The Lubrizol Corp.

This invention relates to a powder coating composition made from at least two components comprising a film-forming resin composition and a transfer efficiency-enhancing amount of at least one additive compound comprising a 4- or 6-membered ring, the ring atoms of the ring comprising at least two heteroatoms, one heteroatom being nitrogen, the second heteroatom being selected from the group consisting of nitrogen, oxygen and sulfur. The additive is incorporated into the powder coating composition by extrusion. The invention also relates to a method of coating a substrate using the foregoing powder coating composition.

Translucent High-Temperature Powder Coatings
U.S. Patent 6,248,824
Issued: June 19, 2001
Inventors: Decker, Owen H., et al
Assigned to: Morton International Inc.

Coating powders are provided which provide high-temperature, translucent coatings useful for light-emitting devices such as incandescent bulbs. The coating powders comprise a binder, at least 90 wt% up to 100 wt% of which is a silicone resin. The coating powders are filled with between about 10 and about 50 phr of fillers selected from the group consisting of needle-like calcium metasilicate, mica, rod-like glass particles, and mixtures thereof, the fillers having aspect ratios between about 8 and about 40.

Powder Coatings Based on Branched Oligoesters and Triazole Blocked Polyisocyanates
U.S. Patent 6,248,843
Issued: June 19, 2001
Inventors: Panandiker, Kamlesh Pai, et al
Assigned to: McWhorter Technologies Inc.

The present invention relates to powder coating compositions that can be cured at low temperatures. The powder coating compositions of the invention include a unique combination of a branched oligoester polyol and triazole blocked isocyanate cross-linking agent which, when cured, results in a coating binder with desirable hardness, flexibility, solvent resistance, corrosion resistance, weatherability and gloss.

Process for the Multilayered Coating of Substrates With Electrophoretic Coating Material and Powder Coating Material
U.S. Patent 6,254,751
Issued: July 3, 2001
Inventors: Reiter, Udo, et al
Assigned to: BASF Coatings AG

The present invention relates to a process for the multilayered coating of substrates with electrodeposition and powder coating materials, in which electrodeposition is used to apply at least one coat of electrodeposition coating material to the substrate. After deposition the substrate is, if desired, wholly or partially air-dried, a coat of powder coating material is then applied, and finally electrodeposition coating material and powder coating material are jointly baked.

Spherical Colored Polyester Particles, Process for Their Preparation, and Their Use for Powder Coatings
U.S. Patent 6,261,690
Issued: July 17, 2001
Inventors: Blatter, Karsten, et al
Assigned to: Aventis Research & Technology GmbH & Co. KG

The invention relates to homogeneously colored polyester particles having a mean particle size of less than 50 micrometers and a narrow particle size distribution, which can be melted at temperatures less than 200°C to form a continuous coating; to a process for their preparation; and to their use for powder coatings.

European Patents

A Powder Paint Binder Composition
Published: March 8, 2000
EP 0 703 256
Assigned to: DSM n.v.

A powder paint binder composition comprising a hydroxyl functional polymer and a crosslinker containing blocked isocyanate groups, characterized in that the crosslinker includes (i) crystalline compound being blocked hexamethylene diisocyanate and (ii) an amorphous compound being HDI trimer.

Primer Composition for Powder Coating
Published: October 4, 2000
EP 0 784 082
Assigned to: Daicel Huls Ltd.

A primer composition for powder coating which comprises an acid-modified diene polymer, an organic amine or ammonia and water, wherein the diene polymer is a polymer which has a molecular weight of at least 500 and is obtained by copolymerizing a compound having a conjugated double bond with a compound selected from the group consisting of (meth)acrylic acid or maleic anhydride; or polymerizing a compound having a conjugated double bond and treating the polymer thus obtained with maleic anhydride.

Powder Paint
Published: January 10, 2001
EP 0 770 605
Assigned to: Vantico AG

A powder coating material based on one or more poly (meth)acrylic resins having free acid groups, comprising a hardener based on epoxide compounds having a molecular weight of no more than 1500, solid at room temperature, consisting of 60 to 100 wt% of diglycidyl-1,4-cyclohexanedicarboxylate consisting (mainly) of trans isomer having a melting point of above 70ºC; the amount of aromatic epoxide components being not higher than 15 wt%.

Aqueous Powder Paint Dispersions
Published: January 10, 2001
EP 0 858 471
Assigned to: BASF Coatings Aktiengesellschaft

Aqueous powder coating dispersion based on epoxy resins consisting of a solid pulverulent component (A) and an aqueous component (B), (A) being a powder comprising (Aa) at least one epoxy resin having an epoxide equivalent weight of from 300 to 5500, (Ab) at least one di- and/or polycarboxylic acid as curing agent, comprising one or more organosilyl groups in the molecule; and component (B) being an aqueous dispersion comprising at least one nonionic thickener.

Weather Resistant Polyamide Powder Coating
Published: February 21, 2001
EP 0 787 536
Assigned to: Degussa-Huls Aktiengesellschaft

A weathering-stable colored polyamide powder coating characterized by at least a single pigmented polyamide coat initially applied to the article to be coated, and at least one unpigmented polyamide topcoat applied thereon, characterized by containing weathering additive(s).

Use of a Polyamide-based Powder Composition for the Coating of Metal Substrates
Published: May 9, 2001
EP 0 706 544
Assigned to: Atofina

Use of a powder coating composition for coating metal substrates, comprising (a) 100 parts of at least one polyamide and (b) up to 30 parts of at least one polymer compatible with said polyamide having hydroxyl functional groups.