Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Compositions to be polymerized by wave energy wherein said...
Reexamination Certificate
2000-09-25
2003-01-21
Nutter, Nathan M. (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Compositions to be polymerized by wave energy wherein said...
C522S096000, C522S100000, C522S109000, C522S110000, C522S111000, C522S024000, C522S007000, C522S008000, C522S012000, C522S031000, C252S600000
Reexamination Certificate
active
06509389
ABSTRACT:
TECHNICAL FIELD
The present invention relates to ultraviolet light curable compositions capable of producing a mar resistant coating on a substrate.
BACKGROUND OF THE INVENTION
Mar resistant coatings are thin film coatings that resist smudging and scratching. These coatings typically have a textured or matt appearance. Mar resistant coatings find utility in many graphics applications, i.e. labeling and detailing. Additionally, mar resistant coatings are applied to wood surfaces to enhance abrasion and chemical resistance without compromising the quality of the underlying wood finish.
Such coatings have previously been formed from compositions of thermoplastic coating material such as thermoplastic, (meth)acrylic or (meth)acrylic-styrene copolymer emulsions. These compositions are applied to the substrate during wet-trap, off-line dry-trap, gravure, offset, silk-screen, flexography and related printing and coating processes. Once applied, the compositions provide superior film characteristics which include high gloss, mar resistance and oil and water resistance. These film characteristics are a function of composition weight and the percentage of solids in the composition. In general, high weight and high solid content correlate to superior film characteristics.
In order to achieve high weight and solid content, high quantities of volatile organic compounds (VOCs) are added to thermosetting compositions. These VOCs do not incorporate into the final coating after curing. Instead, the VOCs escape into the ambient. Once introduced into the environment, VOCs pose substantial hazards associated with inhalation. Such thermosetting solvent based systems are undesirable because of the hazards and expenses associated with VOCs.
UV curable compositions which do not contain VOCs are known in the art. UV compositions are cured through rapid photo-induced polymerizations instead of thermal energy which releases VOCs into the atmosphere. Since the UV curing process is essentially solvent free, the necessity for time consuming and expensive pollution abatement procedures is greatly reduced.
UV curable mar resistant coatings offer several other benefits not associated with thermally cured coatings. First, faster cure times offer substantial economic benefits. Furthermore, heat sensitive materials can be safely coated and cured with UV light without thermal degradation of the heat sensitive substrate. Additionally, UV light is a relatively low cost source of energy due to its widespread availability.
Although UV curable mar resistant coatings are superior to their thermal counterparts, there are still disadvantages inherent in UV curable coatings. Since UV curable mar resistant coatings require compositions which have high molecular weight and viscosity, it is difficult to apply the composition through spraying and brushing. Additionally, many UV curable mar resistant coatings require compositions that are prone to dispersion and instability. By using these compositions, the curing results in an uneven and blemished coating.
Accordingly, there exists a need to provide environmentally safe UV curable mar resistant coatings which exhibit an improved finish and resistance to smudging and scratching. Additionally, there is a need to provide a method of applying the coatings which furthers the goal of improved performance.
SUMMARY OF INVENTION
It is an object of the present invention to provide an improved composition that upon curing by ultraviolet light produces a coating that is mar resistant.
It is another object of the present invention to provide an improved composition that upon curing by ultraviolet light produce a textured coating that is mar resistant.
It is another object of the present invention to provide an improved composition that can be applied by spraying, screen printing, dipping, and brushing.
The present invention discloses an ultraviolet light curable mar resistant composition and method for depositing such a composition to produce a mar resistant layer. The disclosed composition does not contain any significant amount of volatile organic solvents that do not become incorporated in the mar resistant layer after curing. Specifically, the mar resistant composition contains 5% or less volatile organic solvents by weight.
In accordance with one aspect of the invention, an ultraviolet light curable mar resistant composition is provided. The mar resistant composition comprises a mixture of one or more aliphatic acrylated oligomers, wherein the aliphatic acrylated oligomer mixture is present in an amount of about 2% to 40% of the mar resistant composition. All percentages of the mar resistant composition as expressed in this document refer to the weight percentage of the stated component to the total weight of the mar resistant composition.
The mar resistant composition preferably comprises an acrylated epoxy oligomer in an amount of about 2% to 10%, an isobornyl acrylate monomer in an amount of about 15% to 50% of the mar resistant composition, a photoinitiator in an amount of about 2% to 8% of the mar resistant composition, and a talc in an amount of about 25% to 45% of the mar resistant composition.
In accordance with yet another aspect of the invention, a method is provided for depositing a mar resistant coating on a substrate. The method comprises a first step of applying to the substrate a mar resistant fluid-phase composition (“mar resistant composition”). The mar resistant composition comprises a mixture of aliphatic acrylated oligomers, wherein the aliphatic acrylated oligomer is present in an amount of about 2% to 40% of the mar resistant composition. The mar resistant composition also includes an acrylated epoxy oligomer in an amount of about 2% to 10%, an isobornyl acrylate monomer in an amount of about 15% to 50% of the mar resistant composition, a photoinitiator in an amount of about 2% to 8% of the mar resistant composition, and a talc in an amount of about 25% to 45% of the mar resistant composition.
The method also includes a second step of illuminating the mar resistant composition on the substrate with an ultraviolet light to cause the mar resistant composition to cure into the mar resistant coating.
In accordance with this method, the mar resistant composition can be selectively deposited on the substrate at specific locations where mar resistant plating is desired. The mar resistant composition need not be applied to the entire substrate.
BEST MODE FOR CARRYING OUT THE INVENTION
Mar Resistant Compositions
Reference will now be made in detail to presently preferred compositions or embodiments and methods of the invention, which constitute the best modes of practicing the invention presently known to the inventor.
In accordance with one aspect of the invention, a presently preferred ultraviolet light curable mar resistant composition (“mar resistant composition”) is provided. In this preferred embodiment, the mar resistant composition includes a mixture of aliphatic acrylated oligomers. The aliphatic acrylated oligomer mixture is present in an amount of about 2% to 40% of the mar resistant composition. If the mar resistant composition is applied by screen printing, the aliphatic acrylated oligomer mixture is more preferably present in an amount of about 28% to 38%, and most preferably about 32%. If the mar resistant composition is applied by flexographic techniques, the aliphatic acrylated oligomer mixture is more preferably present in an amount of about 22% to 32%, and most preferably about 27%. However, if the mar resistant composition is applied by flexographic techniques and contains an optional flow promoting agent as described below, the aliphatic acrylated oligomer mixture is more preferably present in an amount of about 2% to 8%, and most preferably about 5%. The aliphatic acrylated oligomer preferably comprises one or more urethane oligomers. Suitable aliphatic acrylated oligomers include Radcure Ebecryl 244 (aliphatic urethane diacrylate diluted 10% with 1,6-hexanediol diacrylate), Ebecryl 264 (aliphatic urethane triacrylate diluted 15% with 1,6-hexanedio
Brooks & Kushman P.C.
McClendon Sanza L.
Nutter Nathan M.
UV Specialties, Inc.
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