Morton International, Inc.

Rohm and Haas Company

Richard P Haley

Andrew T Daly

Jeno Muthiah

Joseph J Kozlowski

Eugene P Reinheimer

Paul R Horinka

Glenn D Correll

Edward G Nicholl

Owen H Decker

Karl R Wursthorn

Gregory R Mill

Matthew B Snyder

Michael M Cook

Carryll A Seelig

Navin B Shah

Jeffrey A Ulman

Richard A Kraski, Jr

Navin Shah

Michael G Favreau

The present invention provides UV curable coating powders comprising a blend of one or more than one free radical curable resin and one or more than one cationic curable resin, at least one free radical photoinitiator and at least one cationic photoinitiator, including suitable cross-linking agents and additives to enhance the chemical and physical properties of the coating appearance. The coating powder, preferably finely ground to between 5 and 30 microns in average particle size, is applied to a substrate, heat fused, and cured for an amount of time sufficient to form a powder coating having a low gloss finish.

Coating powders for smooth, low gloss finishes, and powder coatings formed therefrom

A powder coating composition and method of applying it to a substrate, such as medium density fibreboard, consisting of a glycidyl methacrylate resin, a dicarboxylic acid cross-linking agent, a catalyst selected from phosphines, phosphonium, ammonium 2-phenyl-2-imidazoline, substituted imidazoline and isopropyl imidazole Bis-A epoxy resin adduct and a matte texturing agent. The inventive formulation is able to create a matte texture finish on the surface of the substrate. Since the cured final coating is resistant to yellowing and moisture, it is of great utility in the kitchen cabinet making industry.

Matte finish powder

A coating powder, based on glycidyl (meth)acrylate copolymer/carboxylic acid functional polyester chemistry, provides a smooth, weatherable, reduced gloss coating for use on heat sensitive substrates, such as wood. The glycidyl (meth)acrylate copolymer has an epoxy equivalent weight of 250 to 400 and the carboxylic acid functional polyester has a viscosity of 2500 cps or less at 200 C.

Low temperature curing powder coating for producing reduced gloss, weatherable coatings

Low gloss appearance in a coating derived from UV curable powder coatings can be achieved by using UV curable powder containing crystalline components or blends of crystalline and amorphous components and after heat fusing the powders together, allowing the crystalline components in the coating time to flow out and recrystallize to form a matte low gloss finish at a temperature of about the melting point of the crystalline component before curing with UV radiation.

Method for producing low/medium gloss appearance with UV curable powder coatings

Coating powders having a resin system of comprising an epoxy resin and a carboxylic acid functional polymer contain a cure catalyst of formulae (I), (II) or mixtures of (I) and (II):

Coating powders for heat-sensitive substrates

An atomized fluid, such as a mist of water, is applied to a preheated substrate, such as wood, a wood product, paper, or ceramic just prior to or contemporaneously with electrostatically applying a coating powder to the substrate. The atomized fluid is absorbed or adsorbed by the substrate so as to enhance the charge-carrying capacity of the substrate to an extent necessary to promote efficient electrostatic application of the coating powder to the substrate.

Method of applying a coating powder to a substrate

This invention provides a UV curable powder coating composition comprising a particulate blend of a non-crystalline unsaturated polyester base resin, a crystalline unsaturated crosslinker resin co-polymerizable with the base resin, and a photoinitiator, that exhibits reduced or eliminated hazing in the cured coating formed therefrom upon being cured at low temperatures demanded by certain heat sensitive substrates. This is accomplished by incorporating in the powder composition a recrystallization or haze inhibitor which is comprised of a crystalline epoxy resin. When this powder blend is melted for curing, the crystalline crosslinker resin visually appears to separate and recrystallize out of the molten powder less completely than it does in the absence of the recrystallization or haze inhibitor. This prevents a visible haze from developing on the surface of the coating upon curing with UV radiation.

Non-hazing UV curable powder coatings containing crystalline resins

Wood is electrostatically coated with a thermosetting powder coating system in which a mixture of a self-curing epoxy resin and a catalyst therefore is extruded and a low temperature curing agent are both pulverized and the powders are blended with conventional additives to make a coating powder which is deposited on a wooden substrate and heated to cure. The mixture of resin and catalyst does not cure within the extruder but it is made to cure at low temperatures by the separate addition of the curing agent. A small amount of the low temperature curing agent, insufficient to cause substantial curing during extrusion may be used in place of the catalyst.

Two component powder coating system and method for coating wood therewith

Opaquely pigmented or thick filmed powder coatings for heat sensitive substrates, such as wood, wood composites, for example, medium density fiber board, and plastics, that can be fully cured, especially near the substrate, through the incorporation of a dual cure system in the powder comprising a thermal initiator, such as a peroxide, along with a UV initiator. The UV initiator cures the surface, while the thermal initiator cures at the substrate. Surprisingly, virtually no pregelation occurs during the heated melt and flow out step prior to UV curing. Consequently, the hardened film finish formed on the surface exhibits exceptional smoothness which is comparable to that of traditional UV curable powders. The hardened film finish is also fully cured throughout and exhibits exceptional adhesion to the substrate which cannot be achieved with traditional UV curable powders that have been pigmented. Although the dual cure system includes a thermal aspect, these powder coatings are especially suited for coating heat sensitive substrates. The dual thermal and UV curable powders still cure at significantly lower temperatures and significantly faster rates than traditional heat curable powders to make them safe for coating heat sensitive substrates.

Dual thermal and ultraviolet curable powder coatings

Low gloss appearance in a coating derived from UV curable powder coatings can be achieved by using UV curable powder containing crystalline resins or blends of crystalline and amorphous resins and after heat fusing the powders together, allowing the crystalline resins in the coating to cool and recrystallize to a low gloss finish before curing with UV radiation.

Method for producing low gloss appearance with UV curable powder coatings

This invention provides a UV curable powder coating composition comprising a particulate blend of a non-crystalline unsaturated polyester base resin, a crystalline unsaturated crosslinker resin co-polymerizable with the base resin, and a photoinitiator, that exhibits reduced or eliminated hazing in the cured coating formed therefrom upon being cured at low temperatures demanded by certain heat sensitive substrates. This is accomplished by incorporating in the powder composition a recrystallization inhibitor which is comprised of a crystalline epoxy resin. When this powder blend is melted for curing, all of the crystalline resin species tend to separate and recrystallize out of the molten powder slower and less completely than they do in the absence of the recrystallization inhibitor. This prevents a visible haze from quickly developing on the surface of the molten coating before the coating can be cured with UV radiation.

Thermosetting powder coating compositions adapted to form a grainy textured finish on heat sensitive substrates, especially wood products, such as particle board, conductive particle board, and medium density fiber board, without damaging the substrates comprise an epoxy resin, particularly bisphenol A type epoxy resins having low viscosities, either a catalytic curing agent comprising an imidazole, a substituted imidazole, or adduct of an imidazole or substituted imidazole and an epoxy resin, or a curing agent comprising an adduct of a polyamine and an epoxy resin, or a combination of the catalytic curing agent and curing agent, a texturing agent, a flow control agent, optional extender, and optional pigment. The thermosetting powder coatings have a cure time/temperature ranging from about 30 seconds at about 350.degree. F. peak substrate temperature down to about 20 minutes at about 225.degree. F. peak substrate temperature which provides for either a rapid cure or low bake temperature to prevent excessive heat exposure to the heat sensitive substrate, resulting in substantially no physical or chemical degradation of the heat sensitive substrate during baking. The powder coatings are applied to heat sensitive substrates, especially wood products, through electrostatic spraying onto the substrate followed by heating to cure the textured finish uniformly on the surfaces and edges of the substrate. Electrostatic spraying is performed with a triboelectric or corona spray gun and heat curing is performed with a high intensity infrared oven, a convection oven, or combination. Coated heat sensitive substrates having continuous grainy textured finishes that are excellent for hiding substrate surface defects and later appearing scratches are obtained.

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Reading, PA, United States of America

Richard P Haley