MXPA02006765A

MXPA02006765A - Uv curable woodcoat compositions.

Info

Publication number: MXPA02006765A
Application number: MXPA02006765A
Authority: MX
Inventors: Roy C Krohn
Original assignee: Allied Photochemical Inc
Priority date: 2000-01-13
Filing date: 2001-01-11
Publication date: 2005-07-01
Also published as: EP1261655A1; WO2001051533A1; CA2397140A1; AU2001229388A1

Abstract

The present invention discloses an ultraviolet light curable woodcoat composition and method for making such a composition that may be used to produce a coating on a wood object. These coatings are clear and provide protection to the wood object. The disclosed composition does not contain any significant amount of volatile organic solvents that do not become incorporated in the active layer after curing.

Description

COATING COMPOSITIONS FOR WOOD, CURABLE BY ULTRAVIOLET LIGHT TECHNICAL FIELD The present invention relates to compositions curable by ultraviolet light (uv), capable of producing coatings on a wood substrate, on a wood substrate. BACKGROUND OF THE INVENTION Wood surfaces on decks, teakwood boats, wood (treated and untreated), and furniture are typically finished with transparent coatings to provide protection and improve appearance. Traditionally, lacquers containing cellulose compositions are often used to finish wood surfaces. Although not expensive, these lacquers suffer from poor resistance to physical and chemical attack. Due to these disadvantages, cellulose lacquers have been supplanted by heat curable coatings. Although more resistant to physical and chemical attack than cellulose lacquers, heat-curable coatings suffer from their own disadvantages. Heat curable compositions require the use of organic solvents that contain a significant amount of volatile organic compounds (VOCs). These VOCs escape into the atmosphere while the heat curable composition dries. Such solvent-based systems are undesirable due to the hazards and expenses associated with VOCs. Hazards include water and air pollution and the costs include the costs of complying with strict government regulations on solvent emission levels. In contrast, UV curable compositions contain reactive monomers instead of solvents thus eliminating the deleterious effects of VOCs. The use of heat curable compositions not only elevates environmental concerns but there are other disadvantages in their use. These compositions require a high energy for curing, due to the loss of energy, as well as the energy required to heat the coating. Additionally, many heat curable compositions produce poor film properties that result in a decreased value of the final product. Although UV curable compositions exhibit superior properties and performance over their heat curable counterparts, the UV curable compositions themselves suffer from certain disadvantages. In general, UV compositions have high molecular weights and a substantial degree of crosslinking due to the highly reactive nature of the composition. As a result, many of these compositions suffer from low durability and resin shrinkage. With the use of many such compositions, a highly excessive amount of UV light is required to cure them. New formulations that decrease these problems typically suffer from decreased abrasion, chemical resistance and scratches as well as low thermal stability and adhesion. A further disadvantage of typical UV compositions is their lack of stability resulting in dispersion. With some compositions, the suspended solids are precipitated from the solution after a period of one or two days. The dispersion adversely affects the gloss and clarity of the finished product. To combat this problem, new compositions with high viscosities have been formulated that often decrease the flowability of the composition. These viscous formulations regulate spray applications and provide an unusually high wetting thickness. Accordingly, there is a need to provide environmentally safe, UV curable wood coating compositions that provide an improved finish with increased resistance to physical and chemical degradation. Additionally, there is no need to provide a method to apply the composition that carries more. there the goal of improved performance. SUMMARY OF THE INVENTION It is an object of the present invention to provide an improved composition which upon curing by ultraviolet light produces a coating suitable for coating a wood object. It is another object of the present invention to provide an improved composition suitable for coating a wood object that can be applied by spraying, stencil printing, immersion and brush application. The present invention discloses an ultraviolet light curable wood coating composition and a method for making such a composition that can be used to produce a coating on a wood object. The composition described does not contain any significant amount of volatile organic solvents that are not incorporated into the active layer after curing. Specifically, the wood coating compositions contain 5% or less of organic volatile solvents by weight.According to one aspect of the invention, a UV curable wood coating composition is provided. The wood coating composition comprises a mixture of one or more aliphatic acrylated oligomers, wherein the mixture of aliphatic acrylated oligomers is present in an amount of about 10% to 40% of the wood coating composition. All percentages of the wood coating composition as expressed herein, refer to the percentage by weight of the component established with respect to the total weight of the wood coating composition in its fluid state at standard temperature and pressure. The wood coating composition preferably comprises an epoxy oligomer acrylated in an amount of about 5% to 20%, an isobornyl acrylate monomer in an amount of about 40% to 60% of the wood coating composition, a photoinitiator in an amount of about 4% to 12% of the wood coating composition, and a flow promoting agent in an amount of about 0.1% to 8% of the wood coating composition.

According to yet another aspect of the invention, there is provided a method for depositing a coating of wood coating on a substrate. The method comprises a first step of applying to the substrate a fluid phase coating composition of wood ("wood coating composition"). The wood coating composition comprises a mixture of aliphatic acrylated oligomers, wherein the aliphatic acrylated oligomer is present in an amount of about 10% to 40% of the wood coating composition. The wood coating composition also includes an acrylated epoxy oligomer in an amount of about 5% to 20%, an acrylated isobornyl monomer in an amount of about 40% to 60% of the wood coating composition, a photoinitiator in a amount of about 4% to 12% of the wood coating composition, and a flow promoting agent in an amount of about 0.1% to 8% of the wood coating composition. The method also includes a second step of illuminating the wood coating composition on the substrate with an ultraviolet light to cause the wood coating composition to cure in the wood coating coating. According to this method, the wood coating composition can be selectively deposited on the substrate at specific locations where veneering of the wood coating is desired. It does not need to be applied to the total substrate. BEST MODE FOR CARRYING OUT THE INVENTION Composition of Wood Cladding. Reference will now be made in detail to the preferred compositions herein or embodiments and methods of the invention, which constitute the best ways of practicing the invention known to the inventor herein. In accordance with one aspect of the invention, there is provided a UV curable wood coating composition, preferred herein. In this preferred embodiment, the wood coating composition includes a mixture of aliphatic acrylated oligomers. The mixture of aliphatic acrylated oligomers is present in an amount of about 10% to 40% of the wood coating composition. The mixture of aliphatic acrylated oligomers is more preferably present in an amount of about 20% to 30%, and more preferably about 24%. The aliphatic acrylate oligomer preferably comprises one or more urethane oligomers. Suitable aliphatic acrylated oligomers include Radcure Ebecryl 244 (urethane diacrylate diluted to 10% with 1,6-hexanediol diacrylate), Ebecryl 264 (aliphatic urethane triacylate diluted 15% with 1,6-hexanediol diacrylate), and Ebecryl 284 (aliphatic urethane diacrylate diluted 12% with 1,6-hexanediol diacrylate), urethanes, commercially available from Radcure UCB Corp. of Smyrna, Georgia; Sartomer CN-961E75 (aliphatic urethane diacrylate mixed with 25% ethoxylated trimethylol propane triacrylate), CN-961H81 (aliphatic urethane diacrylate mixed with 2 (2-ethoxyethoxy) ethyl acrylate 19%), CN-963A80 (diacrylate of aliphatic urethane mixed with tripropylene glycol 20% diacrylate), CN-964 (aliphatic urethane diacrylate). CN-966A80 (aliphatic urethane diacrylate mixed with tripropylene glycol 20% diacrylate), CN-982A75 (aliphatic urethane diacrylate mixed with tripropylene glycol diacrylate 25%) and CN-983 (aliphatic urethane diacrylate), commercially available from Sartomer Corp. of Exton, Pennsylvania; TAB FAIRAD 8010, 8179, 8205, 8210, 8216, 8264, M-E-15, UVU-316, commercially available from TAB Chemicals of Chicago Illinois; and Echo Resin ALU-303, commercially available from Echo Resins of Versaille, Mossouri; and Genomer 4652, commercially available from RNA Radiation Curing of Aurora, IL. The aliphatic acrylated oligomers include Ebecryl 264 and Ebecryl 28 4. Ebecryl 264 is an aliphatic urethane triacrylate supplied as an 85% solution in hexanediol diacrylate. Ebecryl 284 is aliphatic urethane diacrylate of 1200 molecular weight diluted with 1,6-hexanediol diacrylate. The combination of these materials can also be used here. This preferred wood coating composition further includes an acrylated epoxy oligomer. The acrylated epoxy oligomer is present in an amount of about 5% to 20%. The acylated apoxy oligomer is present more preferably in an amount of about 8% to 16%, and more preferably about 12%. Suitable acrylated epoxy oligomers include Radcure Ebecryl 3603 (epoxy novolac acrylate diluted 20% with tripropylene glycol diacrylate), commercially available from Radcure UCB Corp .; Sartomer CN-120 (dyspunctional bisphenol-based epoxy acrylate) and CN124 (difunctional bisphenol-based epoxy acrylate), commercially available from Sartomer Corp .; and Echo Resin TME 9319 and 9345, commercially available from Echo Resins. The preferred acrylated epoxy oligomer is Ebecryl 3603, which is tri-functional acrylated epoxy novolac. Combinations of these materials can also be used here. The preferred wood coating composition also includes an isobornyl acrylate monomer in an amount of about 40% to 60%. The isobornyl acrylate monomer is present more preferable in an amount of about 45% to 55%, and more preferably about 52%. Suitable isobornyl acrylate monomers include Sartomer SR-423 (isobornyl methacrylate). and SR-506 (isobornyl acrylate) CH2 available from Sartomer Corp .; Radcure IBOA (isobornyl acrylate), commercially available from Radcure Corp .; IBOA and IBOMA, commercially available from CPS Chemical; and Genomer 1121, commercially available from RNA Radiation Curing. Preferred isobornyl acrylate monomers are Radcure IBOA, commercially available from, Radcure Corp. The combination of these materials can also be employed herein. The suitable wood coating composition also includes a photoinitiator in an amount of about 4% to 12% of the wood coating composition. The photoinitiator is present more preferably in an amount of about 6% to 10%, and more preferably about 8%. Suitable photoinitiators include Irgacure 184 (1-hydroxycyclohexyl phenyl ketone), Irgacure 907 (2-methyl-l- [4- (methylol) phenyl] -2-morpholino propan-l-one), Irgacure 369 (2-benzyl-2) -N, N-dimethylamino-1- (-morpholinophenyl) -1-butanone), Irgacure 500 (the combination of 1-hydroxycyclohexyl phenyl ketone and 50% benzophenone), Irgacure 651 (2, 2-dimethoxy-2-phenyl) acetophenone), Irgacure 1700 (the combination of bis (2,6-dimethoxybenzoyl-2,4,4-trimethylpentyl phosphine oxide and 75% of 2-hydroxy-2-methyl-1-phenyl-propane-1-one) , DAROCUR 1173 (2-hydroxy-2-methyl-1-phenyl-1-propane) and DAROCUR 4265 (the combination of 50% 2, 4, 6-trimethylbenzoyldiphenyl-phosphine oxide and 50% 2-hydroxy-2) -methyl-l-phenyl-propan-l-one), commercially available from Ciba-Geigy Corp., Tarrytown, NY; CYRACURE UVI-6974 (mixed salts of triaryl sulfonium hexafluoroantimonate) and CYRACURE UVI-6990 (mixed salts of hexafluorophosphate triaryl sulfonium) commercially available from Union Car bide Chemicals and Plastics Co. Inc., Danbury, Conn .; and Genocure CQ, Genocure BOK, and Genocure M.F., commercially available from RNA Radiation Curing. The preferred photoinitiator is Irgacure 1700 commercially available from Ciba-Geigy of Tarrytown, New York. Combinations of these materials can also be used here. The known wood coating composition still further includes a flux promoting agent in an amount of about 0.1% to 8%, and preferably about 4.5%, of the wood coating composition. Suitable flow promoting agents include Genorad 17, commercially available from Radiation Curing RNA; and Modaflow, commercially available from Monsanto Chemical Co., St. Louis, Missouri. The preferred flow promoting agent is Modaflow which is a copolymer of ethyl acrylate and 2-ethylhexyl acrylate which improves the flow of the composition. The combinations of these materials can be used here. To illustrate, the following example establishes a coating composition for wood preferred herein, according to this aspect of the invention. Example 1 This example provides a preferred wood coating composition according to the invention. The wood coating composition is made of the following components: In this example the IBOA and Irgacure 1700 are mixed in a container with a propellant blade mixer for 30 seconds at a speed of 500 to 1000 rpm. In the next stage, the Ebecryl 264, the Ebecryl 284, the Ebecryl 3603, and odaflow are introduced into the container and mixed for 1 to 2 minutes at a speed of 2000 rpm. Mixing is temporarily suspended if the temperature exceeds 100 ° C. Method for depositing a coating on a wooden substrate. According to yet another aspect of the invention, there is provided a method for depositing a coating for coating wood on a suitable substrate. The method comprises a first step of applying a fluid phase composition of wood coating ("wood coating composition"). The wood coating composition comprises a mixture of acrylated oligomers, wherein the aliphatic acrylated oligomer is present in an amount of about 10% to 40% of the wood coating composition. The wood coating composition also includes an epoxy oligomer acrylated in an amount of about 5 to 20%, an isobornyl acrylate monomer in an amount of about 40% to 60% of the wood coating composition, a photoinitiator in a amount of about 4% to 12% of the wood coating composition, and a flow promoting agent in an amount of about 0.1% to 8% of the wood coating composition. The preferred wood coating compositions according to this method are those described herein, for example, including the compositions described in Example 1. The wood coating composition can be applied to the substrate using a number of different techniques. The wood coating composition can be applied, for example, by direct brushing application, or sprayed onto the surface of a substrate. It can also be applied using a stencil printing technique. In such a stencil printing technique, a "screen" is the term used in the stencil printing industry is used to regulate the flow of the liquid composition on the surface of the substrate. The wood coating composition would typically be applied to the screen as the latter comes into contact with the substrate. The wood coating composition flows through the silk screen to the substrate, where it adheres to the substrate as the desired film thickness. Stencil printing techniques suitable for this purpose include known techniques, but wherein the process is adjusted in known manners to persons of ordinary skill in the art to accommodate the viscosity, fluidity and other properties of the liquid phase composition, the substrate and its surface properties, etc. Flexographic techniques, for example, using guide rolls for contacting the wood coating composition with a coiling substrate, can also be used. The method includes a second step of illuminating the fluid phase composition of the wood coating on the substrate with ultraviolet light to cause the fluid phase composition of the wood coating to cure in the wood coating coating. This illumination can be carried out in any number of ways, provided that the ultraviolet light or radiation impinges on the wood coating composition so that the wood coating composition is polymerized to form the coating, layer, film, etc. , and heal like that. The cure preferably takes place by free radical polymerization, which is initiated by a source of ultraviolet radiation. The photoinitiator preferably comprises a photoinitiator, as described above. Various sources of ultraviolet light can be used, depending on the application. Preferred ultraviolet radiation sources for a number of applications include known ultraviolet lighting equipment, with power intensity settings of, for example, 125 watts, 200 watts, and 300 watts per 6.45 square centimeters (square inch). While the embodiments of the invention have been described and illustrated, it is not intended that these embodiments illustrate and describe all possible forms of the invention. Instead, that the words used in the specification are words of the description rather than constraints, and it is understood that various changes can be made without departing from the spirit and scope of the invention.

Claims

CLAIMS 1.- A photocurable wood coating composition, characterized in that it comprises: a mixture of acrylated aliphatic oligomers; an acrylated epoxy oligomer; an isobornyl acrylate monomer; a flow promoting agent; and a photoinitiator wherein the photocurable composition is capable of being cured in a protective coating on a wood object and does not contain any significant amount of volatile organic solvents that are not incorporated into the protective coating.
2. The photocurable wood coating composition according to claim 1, characterized in that: the acrylated epoxy oligomer is from about 5% to 20% by weight of the wood coating composition; the isobornyl acrylate monomer is from about 40% to 60% by weight of the wood coating composition; the photoinitiator is from about 4% to 12% by weight of the wood coating composition; the mixture of acrylated aliphatic oligomers is from about 10% to 40% by weight of the wood coating composition; and the flow agent is present in an amount of about 0.1% to 8% of the weight of the wood coating composition.
3. The photocurable wood coating composition according to claim 1, characterized in that: the acrylated epoxy oligomer is from about 8% to 16% of the weight of the wood coating composition; The isobornyl acrylate monomer is from about 45% to 55% by weight of the wood coating composition; the photoinitiator is from about 6% to 10% by weight of the wood coating composition; the mixture of acrylated aliphatic oligomers is from about 20% to 30% by weight of the wood coating composition; and the fluidity promoting agent is present in an amount of about 0.1% to 8% of the weight of the wood coating composition. 4. - The photocurable wood coating composition according to claim 1, characterized in that: the acrylated epoxy oligomer is about 12% by weight of the wood coating composition; the isobornyl acrylate monomer is about 52% by weight of the wood coating composition; the photoinitiator is about 8% of the weight of the wood coating composition; the mixture of acrylated aliphatic oligomers is about 24% by weight of the wood coating composition; and the fluidity promoting agent is about
4.5% by weight of the wood coating composition.
5. - The wood coating composition according to claim 1, characterized in that the isobornyl acrylate monomer is selected from the group consisting of isobornyl acrylate, isobornyl methacrylate and mixtures thereof.
6. - The wood coating composition, according to claim 1, characterized in that the photoinitiator is selected from the group consisting of: 1-hydroxylichelohexyl phenyl ketone; 2-methyl-l- [4- (methylol) phenyl] -2-morpholinopropan-1-; the combination of 50% of 1-hydroxycyclohexyl phenyl ketone and 50% of benzophenone; 2, 2-dimethoxy-1, 2-diphenyletan-1-one; the combination of 25% bis (2,6-dimethoxybenzoyl-2, 4-, -trimethyl pentyl phosphine oxide and 75% 2-hydroxy-2-methyl-1-phenyl-1-propan-1-one oxide; 2-hydroxy -2-methyl-1-phenyl-1-propane, the combination of 50% of 2,4,6-trimethylbezoyldiphenyl phosphine oxide and 50% of 2-hydroxy 2-methyl-1-phenyl-propane-1-one mixed triaryl sulfonium hexafluoroantimonate salts, mixed triaryl sulfonium hexafluorophosphate salts, and mixtures thereof
7. - The wood coating composition, according to claim 1, characterized in that the acrylated epoxy oligomer is selected from from the group consisting of: epoxy novolac acrylate diluted to 20% by weight with tripropylene glycol diacrylate; epoxy acrylate based on functional bisphenol; and mixtures thereof.
8. - The wood coating composition according to claim 1, characterized in that the flow or flow promoting agent is a copolymer of ethyl acrylate and 2-ethylhexyl acrylate.
9. - A method for coating a substrate with a photocurable wood coating composition, the method is characterized in that it comprises: applying the wood coating composition to the substrate, wherein the wood coating composition includes: the epoxy oligomer acrylated in an amount of about 5% to 20% by weight of the wood coating composition; the isobornyl acrylate monomer in an amount of about 40% to 60% by weight of the wood coating composition; the photoinitiator in an amount of about 4% to 12% by weight of the wood coating composition; the aliphatic oligomer mixture acrylated in an amount of about 10% to 40% by weight of the wood coating composition; and the flow promoting agent an amount of about 0.1% to 8% by weight of the wood coating composition. illuminating the wood coating composition with sufficient ultraviolet light to cause the wood coating composition to cure in a protective coating; wherein the wood coating composition does not contain any significant amount of volatile organic solvents that are not incorporated in the protective coating.
10. The method according to claim 9, characterized in that the ultraviolet light used in the lighting impinges on the wood coating composition, so as to cause the wood coating composition to form a coating as it cures. eleven . - The method according to claim 9, characterized in that the method of applying the coating composition for wood is by spraying. 12. - The method according to claim 9, characterized in that the method of applying the coating composition for wood is by stencil printing. 13. - The method according to claim 9, characterized in that the method of applying the composition is submerging the substrate in the composition sufficiently to cause the composition uniformly review the substrate. 14. - The method according to claim 9, characterized in that the method of applying the coating composition for wood is by brushing. 15. - The method according to claim 9, characterized in that the method of applying the wood coating composition is to selectively deposit the substrate at predetermined locations. 16. A method for coating a substrate with a photocurable wood coating composition, the method characterized in that it comprises: applying the wood coating composition to the substrate, wherein the wood coating composition includes: the acrylated epoxy oligomer in an amount of about 8% to 16% by weight of the wood coating composition; the isobornyl acrylate monomer in an amount of about 45% to 55% by weight of the wood coating composition; the photoinitiator in an amount of about 6% to 10% of the weight of the wood coating composition; The mixture of aliphatic oligomers acrylated in an amount of about 20% to 30% by weight of the wood coating composition; and the fluidity promoting agent in an amount of about 0.1% to 8% of the weight of the wood coating composition; and illuminating the wood coating composition with a sufficient ultraviolet light to cause the wood coating composition to cure in a protective coating: wherein the wood coating composition does not contain any significant amounts of volatile organic solvents that are not incorporated within the protective coating or coating. 17. The method according to claim 16, characterized in that the acrylated epoxy oligomer is approximately 12% by weight of the wood coating composition; the isobornyl acrylate monomer is about 52% by weight of the wood coating composition; the photoinitiator is about 8% of the weight of the wood coating composition; the mixture of acrylated aliphatic oligomers is about 24% by weight of the wood coating composition; and the fluidity promoting agent is about 4.5% by weight of the wood coating composition. 18. A method for preparing a photocurable wood coating composition, characterized in that it comprises: mixing an isobornyl acrylate monomer and a photoinitiator in a container; introducing a flow promoting agent and an acrylated epoxy oligomer into the container; mix the flow promoting agent and the acrylated epoxy oligomer.