JP2014210924A - Uv curable coating composition containing aliphatic urethane acrylate resin - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a UV curable coating that offers properties of improved exterior durability, UV stability, thermal stability and flexibility, along with high scratch and abrasion resistance.SOLUTION: A UV curable coating composition includes a unique blend of a plurality of aliphatic urethane acrylate resins. The coating composition may further include two or more, preferably three or more polyfunctional acrylates, a photoinitiator of diphenylphosphine oxide type, α-hydroxyketone type or the like, and a stabilizer such as a hindered amine light stabilizer, a UV absorber or an organic-inorganic hybrid material synthesized through a sol gel process. Coated articles and methods for their production involving the use of the coating composition are also provided.

Description

  The present invention relates generally to forming a polymer coating on a substrate, and in some embodiments, coating compositions, coated articles, and their methods that involve using a blend of a plurality of resins of a selected type. It relates to a manufacturing method.

  As a further background, plastic substrates such as, but not limited to, polycarbonate, acrylic, and polyester are often used as an alternative to more traditional materials such as glass in various applications. Plastics can provide superior properties such as impact resistance and optical clarity while providing weight reduction and rich design flexibility. Despite the many benefits that plastics provide, they often provide the desired degree of chemical resistance, scratch resistance, damage resistance, and abrasion resistance, UV resistance, and / or outdoor durability. It has a big drawback of not.

  Both conventional thermosetting coatings and ultraviolet (UV) curable coatings for outdoor applications that exhibit scratch and abrasion resistance can be used with these various plastics when the angle or time of direct exposure is limited. It is known to provide adequate protection and performance of the substrate. Also, UV curable coatings are often the best preferred coatings because they offer other advantages such as improved cycle times and reduced workload during the process over those cured by conventional methods. Are known.

  Despite the many advantages of current outdoor coatings-more specifically UV curable coatings-they still have not met all the demands, often using traditionally available techniques. It lacks desirable properties and combinations of properties that are very difficult to achieve. Traditional UV overcoats for scratch and abrasion resistant applications are mostly composed primarily of highly functional and highly reactive acrylates. Although these features provide the desired hardness properties, they tend to cause shrinkage and steric hindrance of the cured resin. Steric hindrance forms more unreacted acrylate bonds in the cured polymer resin than desired, which makes the cured coating more susceptible to premature UV and environmental degradation. Furthermore, known UV topcoat layers produce a rigid and non-flexible coating when cured. Such inflexible coatings may crack, reduce outdoor durability, or otherwise when subjected to expansion or contraction conditions during processing or practical use, or when applied to materials with high internal stress. Give improper performance such as defects. Thus, it may be difficult to provide the desired level of high surface hardness, scratch resistance, chemical resistance, UV resistance, and outdoor durability with a single coating composition.

  In a preferred embodiment, the present invention provides improved outdoor durability, UV stability, thermal stability, especially for design applications in which the coating material is exposed to harsh atmospheres, along with high scratch and abrasion resistance. And address the need for UV curable coatings that provide flexibility properties. Further disclosed in the present invention are methods using these materials and the resulting coated articles.

  In some forms, the present invention provides a coating composition comprising a unique blend of UV curable resins. The first resin of the blend has an aliphatic polyisocyanate component containing iminooxadiazinedione, isocyanurate, uretdione, urethane, allophanate, biuret, or oxadiazinetrione groups and a molecular weight of about 100 to about 2000. An aliphatic urethane acrylate formed by reaction with an alcohol component comprising a linear or branched alkyl ester of at least one monobasic, hydroxyl-functional meth (acrylic) acid. The coating composition is also formed, at least in some embodiments, by reaction of (i) a polyfunctional acrylate with an aliphatic urethane based on a polymer of an alkyl carbon monocyclic diisocyanate; ii) encompassed by Formula II disclosed below; also includes a second aliphatic urethane acrylate. In a preferred form, the first aliphatic urethane acrylate has a molecular weight in the range of about 800 to about 2500 g / mol and / or the first aliphatic urethane acrylate has about 3 to about 5 polymerizable per molecule. Contains acrylate groups. In a preferred form, the molecular weight of the second aliphatic urethane acrylate ranges from about 500 to about 2000 g / mol. The coating composition may also include a solvent that aids in the controlled application and processing of the material. The coating composition also comprises at least two, preferably three or more polyfunctional acrylates each having a molecular weight between 170 and 1000, and a minimum of two polymerizable unsaturated groups per molecule. May be. The coating composition may also contain stabilizers such as hindered amine light stabilizers and / or UV absorbers of benzotriazoles or benzotriazines, or derivatives thereof. The coating composition may also include one or more organic-inorganic hybrid materials synthesized by a sol-gel method.

  In a further aspect, the present invention provides a coated article or process involving the use of the coating composition described herein. In some forms, the coated articles of the present invention are formed by reaction of a base plastic material having a thickness of about 0.75-20 mm, and a coating composition described herein, of about 3 to about 35 microns. Having a cured topcoat with a thickness in the range. Cured topcoats can provide a high degree of scratch resistance, abrasion resistance, damage resistance, and chemical resistance, along with excellent UV resistance, outdoor durability, and thermal stability. In some forms, the methods of the present invention include applying the coating compositions described herein by spray coating, flow coating, or curtain coating methods.

  Further aspects of the invention and its features and advantages will become apparent from the description herein.

FIG. 1 is a perspective partial cutaway view of an automobile having a coated front illumination lens according to one embodiment of the present invention. 2 is a partial cutaway side view of the automobile of FIG.

  For the purpose of promoting an understanding of the principles of the invention, reference will now be made to certain embodiments and specific language will be used to describe the same. However, this is not intended to limit the scope of the invention, and changes and further modifications in the apparatus shown and further application of the principles of the invention described herein are relevant to the present invention. One of ordinary skill in the art would normally conceive.

  As disclosed above, in some forms thereof, the present invention relates to unique coating compositions, and methods and coated articles that employ or include coating compositions. In a preferred form, the coating composition comprises a novel resin blend comprising first and second acrylated aliphatic urethane resins. Such a coating composition comprises at least an aliphatic polyisocyanate component containing iminooxadiazinedione, isocyanurate, uretdione, urethane, allophanate, biuret, or oxadiazinetrione groups and at least one monobasic, hydroxyl functional group. A first urethane acrylate resin formed by reaction with an alcohol component containing a linear or branched alkyl ester of meth (acrylic) acid.

In a preferred form, the first urethane acrylate resin has a molecular weight between about 800 and about 2500 g / mol. More preferably, the first acrylated aliphatic urethane has a molecular weight of about 1000 to about 1600 g / mole, and to date is most preferred for a molecular weight of about 1400 g / mole to work. As will be appreciated, the molecular weights of the polymerizable resins provided herein are number average molecular weights unless otherwise indicated. The alcohol component used in forming the first urethane acrylate resin may have a molecular weight of about 100 to about 2000 g / mol. In some variations, the first urethane acrylate is
(A) 20-100 mol% of formula I: based on the number of moles of polyisocyanate component:

(here,
R ¹ , R ² , and R ^{3 in} Formula I are the same or different and represent a linear or branched C ₄ -C ₂₀ (cyclo) alkyl group;
X is the same or different and represents an isocyanate group or an isocyanate group-containing group that may also contain an iminooxadiazinedione, isocyanurate, uretdione, urethane, allophanate, biuret, or oxadiazinetrione group;
R ¹ , R ² , and R ^{3 in} Formula I are bound to a nitrogen atom)
A polyisocyanate component comprising a polyisocyanate trimer containing iminooxadiazinedione groups encompassed by
(B) an alcohol component comprising at least one linear or branched C ₁ -C ₁₂ alkyl esters of a single basic with hydroxyl-functional (meth) acrylic acid;
And the reaction product. For further information regarding such urethane acrylate resins suitable for use in the present invention, see US Pat. No. 6,191,181 (in its entirety, including disclosure of manufacturing methods and final urethane acrylate resin compounds that can be used in the present invention). Inclusive). Resins suitable for use as the first aliphatic urethane acrylate can be obtained, for example, from Bayer Material Science under the trade name Desmolux.

  In some embodiments, the first urethane acrylate has a functionality of about 2 to about 6, more preferably about 3 to about 5, and most preferably about 3.5 to about 4. Additionally or alternatively, the first urethane acrylate can exhibit the ability to cure with ultraviolet light to provide a hard coating having a pencil hardness of, for example, greater than 4, for example, from about 4 to about 7.

  The first aliphatic urethane acrylate resin can be provided alone or one or more reactive diluents such as HDDA (1,6-hexanediol diacrylate), TPGDA (tripropylene glycol diacrylate), DPGDA. (Dipropylene glycol diacrylate), TMPTA (trimethylolpropane triacrylate), and / or GPTA (glycerol propoxytriacrylate) can be mixed and provided. When mixed with one or more reactive diluents, the first aliphatic urethane acrylate resin may constitute from about 70% to about 90% of the mixture in certain embodiments.

  In some embodiments, the coating composition of the present invention also includes a second urethane acrylate resin that is different from the first urethane acrylate resin. The second urethane acrylate resin comprises a multifunctional acrylate (eg, having a molecular weight of about 190 to about 500 and containing at least 3 polymerizable unsaturated groups per molecule), a polymer of alkyl carbon monocyclic diisocyanate, It can be formed by reaction with aliphatic urethanes based on alkane polyol polyacrylates. In some embodiments, the second urethane acrylate resin has the formula II:

Wherein A ¹ , A ² , and A ³ are each of formula III:

(Wherein R ¹ , R ² , and R ³ in formula III may be the same or different, each being a linear aliphatic group having 2 to about 12 carbon atoms, or 4 to An alicyclic group having about 12 carbon atoms)
Is the basis of
Is covered by R ¹ , R ² , and R ^{3 in} Formula III are each preferably an alkylene group having from 2 to about 12 carbon atoms. Compounds of formula II are described, for example, in US Pat. No. 5,658,672 (herein incorporated by reference in its entirety, including the preparation methods that can be used in the present invention and the disclosure of the final compounds encompassed by formula II above) Inclusive). In this' 672 patent, Ebecryl 8301 (Cytec Surface Specialties, Smyrna, GA) that can be used in the present invention comprises a diluent and a hexafunctional acrylate oligomer of formula II, respectively, in a weight ratio of about 48:52, It is taught that the diluent is a blend (ethylene / diethylene glycol diacrylate (based on hydroxyethyl acrylate)), primarily ethylene glycol diacrylate.

  Preferably, the second urethane acrylate resin has a molecular weight in the range of about 500 to about 2000 g / mol, more preferably in the range of about 800 to about 1000 g / mol, and most preferably to date about 800 g / mol. In some embodiments, the second urethane acrylate has a functionality of about 2 to about 10, more preferably about 4 to about 8, and most preferably about 6.

  As disclosed above, some aspects of the invention relate to a coating composition comprising a blend of a resin comprising the first urethane acrylate resin discussed above and the second urethane acrylate resin discussed above. In preferred such embodiments, excluding the inert solvent present in the composition, the first urethane acrylate resin comprises from about 10% to about 40% by weight of the composition. More preferably, in such embodiments, excluding the inert solvent present, the first urethane acrylate resin comprises from about 10% to about 30%, even more preferably from about 15 to about 25% of the composition. . With respect to the second urethane acrylate resin, it preferably comprises about 20% to about 50%, more preferably about 25-35% of the coating composition, excluding any solvent present.

  In another aspect of the invention as defined herein, the first urethane acrylate resin and the second acrylate resin are each about 1:10 to about 10: 1, more preferably about 1: 5 to 5: 1, Most preferably, it is included in the coating composition in a weight ratio or molecular ratio of about 1: 3 to about 3: 1. In some specific embodiments, the first and second urethane acrylate resins are present in a weight ratio or molecular ratio of about 1: 2 to about 2: 1, respectively.

  When the first and second urethane acrylate resins are included in the blended resin coating composition, the UV cured coating has a high surface hardness as measured using steel wool according to FMVSS 108 and Taber abrasion according to ASTM-D1044. Preferred compositions to form can be provided. Furthermore, preferably blended coatings comprising these urethane acrylates provide excellent weathering properties quantified by the widely accepted accelerated and natural weathering test methods and thermal crack resistance. They also provide advantageous cure rates and material compatibility.

  The surface hardness of the resin blend coating composition disclosed herein can be further improved by adding an acrylated organic-inorganic hybrid material, usually produced by a sol-gel process. A preferred organic-inorganic hybrid material is a spherical, non-porous and amorphous, multifunctional acrylate having a molecular weight of about 200 to about 450 and at least two polymerizable unsaturated groups per molecule, about 5 nm. Silica particles in the range of ~ 100 nm. The preferred final molecular weight of the organic-inorganic hybrid material is between about 500 and about 3000. Improved surface hardness properties can be achieved by adding from about 5% to about 35% by weight of such acrylated organic-inorganic hybrid material (excluding any inert solvent present). More preferably, when included, the content of the acrylated organic-inorganic hybrid material is from about 8% to about 18% by weight excluding the inert solvent present. Examples of suitable organic-inorganic materials that can be used in the compositions, coatings, and coated articles of the present invention include: Etercure 601A-35, Etercure 601B-35, Etercure 601C-35, Etercure 601H-35 (Eternal Chemical Company) , Ltd. Taiwan) and RX11402 (Cytec Surface Specialties, Smyrna, GA).

  The coating composition of the present invention can also include one or more multifunctional acrylates. The one or more multifunctional acrylates used in the coating composition of the present invention are determined by the desired application viscosity, application method, and performance characteristics. Exemplary multifunctional acrylates are of the reactive diluent type having a molecular weight of about 170 to about 1000 and containing at least two polymerizable unsaturated groups per molecule. Typical multifunctional acrylates include dipropylene glycol diacrylate, tripropylene glycol diacrylate, 1,6-hexanediol diacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, tricyclodecane dimethanol diacrylate, -Trimethylolpropane tetraacrylate, dipentaerythritol pentaacrylate, trimethylolpropane triacrylate, tetraethylene glycol diacrylate and the like. Preferred coating compositions contain two such multifunctional acrylates, each in an amount of about 5% to about 55% by weight. In some preferred embodiments, the coating composition of the present invention comprises from about 5% to about 15% of a first such multifunctional acrylate having two polymerizable unsaturated groups per molecule, and from about 15% to About 25% of a second such multifunctional acrylate having 3 polymerizable unsaturated groups per molecule.

  Many photoinitiators and / or sensitizers are suitable for use in the coating composition of the present invention. Among these, a group of suitable photoinitiators are diphenylphosphine oxide type photoinitiators such as 2,4,6-trimethylbenzoyldiphenylphosphine oxide and bis-2,4,6-trimethylbenzoyldiphenylphosphine oxide. Phenylphenyloxylate type such as oxyphenylacetic acid 2- [2-oxo-2-phenylacetoxyethoxy] ethyl ester and oxyphenylacetic acid 2- [2-hydroxyethoxy] ethyl ester; 1-hydroxycyclohexyl phenyl ketone; 2-hydroxy-1- [4- (2-hydroxyethoxy) phenyl] -2-methyl-1-propanone, 2-hydroxy-2-methyl-1-phenyl-1-propanone, and difunctional α-hydroxy ketone Α-Hydroxyketone Thailand It is. A preferred embodiment comprises a blend of diphenylphosphine oxide and an α-hydroxyketone type photoinitiator, with a more preferred blend of bis-2,4,6-trimethylbenzoyldiphenylphosphine oxide and a bifunctional α-hydroxycyclohexyl phenyl ketone. It is.

  At least one photoinitiator is added to the preferred formulation in an amount sufficient to obtain the desired curing reaction. In a preferred formulation of the present invention, a blend of at least two photoinitiators is included in an amount from about 0.25% to about 15% by weight. The range of the first preferred photoinitiator (diphenylphosphine oxide type described above) is in some embodiments from about 0.5% to about 2.5%. The range of the second preferred photoinitiator (the α-hydroxyketone type described above) is about 4% to about 13% in some embodiments. In some inventive formulations, a further benefit is by adding a third photoinitiator in the range of about 0.5% to about 4.5%, for example a hydroxyalkylphenone type photoinitiator. can get. The amount of one or more photoinitiators to include will vary based on many factors such as the type of UV curing device, UV device settings, curing rate, and desired durability.

  Preferred coating compositions of the present invention also include a stabilizing material that maximizes outdoor durability and UV resistance. Suitable stabilizers include hindered amines and UV absorbers such as benzotriazole or benzotriazine derivatives. The amount of stabilizer in the system will vary depending on the application parameters and desired performance characteristics that maximize weatherability without sacrificing curing reaction and surface hardness. In a more preferred composition, the hindered amine ranges from about 0.5% to about 4.5%, the hydroxyphenylbenzotriazine (or other suitable compound) ranges from about 2% to about 15%, Antioxidants range from about 0.25% to about 2.0%.

  Preferred coating compositions of the present invention contain one or more inert solvents. In some embodiments, the composition comprises a blend of a plurality of inert solvents. Examples of suitable inert solvents include ester solvents such as ethyl acetate and butyl acetate; ketone solvents such as acetone and methyl ethyl ketone; alcohol solvents such as isopropyl alcohol and sec-butyl alcohol. The amount and type of solvent in the composition will vary depending on the application method and equipment capabilities and preferences. For example, in flow coat or curtain coat applications, the inert solvent should not be too aggressive to the base plastic of the molded article. In some forms of the invention, the inert solvent content in the coating composition may range from 0 wt% to 80 wt% overall, with the preferred solvent content being 35 wt% to 65 wt%. .

  Various other additives can also be included in the coating composition of the present invention to further improve the appearance and / or performance characteristics of the cured coating. Examples of suitable additives include reactive and non-reactive acrylic or silicone flow agents, slip agents, and anti-damage agents, and leveling agents that aid in substrate wetting and leveling of the composition, as well as thermal and process stability. Is a phenol-based antioxidant that gives. One particularly preferred additive is a polysiloxane solution such as that commercially available under the name Byk 301 (BYK-CHEMIE, Wallingford, Conn.).

  In some preferred embodiments, the inert organic solvent in an amount of about 10-50% by weight, the first aliphatic urethane acrylate discussed above in an amount of about 3% to about 20% by weight, about 3% by weight. The second aliphatic urethane acrylate as discussed above in an amount of about 20% by weight, a reactive diluent component in an amount of about 5% to about 30% by weight (the reactive diluent component is one or more polyfunctional). A resin blend coating composition comprising, for example, one or more photoinitiators selected from those shown herein, and one or more light stabilizers selected from, for example, those shown herein. The More preferred compositions of this embodiment further comprise an antioxidant and a flow additive, for example as shown herein. In some forms, in the preparation of the first aliphatic urethane acrylate, X in Formula I represents an isocyanate group. In another preferred form, X in formula I represents an isocyanate group-containing group that also contains an iminooxadiazinedione group; or X in formula I represents an isocyanate group-containing group that also contains an isocyanurate group; X in formula I represents an isocyanate group-containing group that also contains a uretdione group; or X in formula I represents an isocyanate group-containing group that also contains a urethane group; or X in formula I further contains an allophanate group Or X in formula I represents an isocyanate group-containing group that also contains a biuret group; or X in formula I represents an isocyanate group-containing group that also contains an oxadiazinetrione group. In these embodiments, the first aliphatic urethane acrylate and the second aliphatic urethane acrylate may also have any other characteristic properties disclosed herein.

  The coating composition of the present invention can be applied to articles selected by various conventional coating methods such as conventional spray, HVLP spray, air assisted / airless spray, rotary atomization, flow coat, curtain coat, or roll coat. Can be applied. Furthermore, the coating composition can be applied directly to the substrate or onto a precured or uncured coating. The desired film pressure of the cured film formed using the coating composition of the present invention is from about 3 microns to about 40 microns, and the most preferred dry film thickness is from about 5 microns to about 20 microns.

Once applied, the coating composition can be cured by irradiation with ultraviolet energy as is known to those skilled in the art. In this regard, irradiation continues until curing is complete, and preferred exposure times are usually less than 300 seconds, more preferably from about 20 to about 100 seconds. The curing temperature can vary from room temperature to the heat deflection temperature of the substrate, while the curing distance is typically between about 2 to about 18 inches from a UV source that achieves a minimum strength of about 100 mW / cm ^2. is there.

  In order to cure the overcoat layer, an ultraviolet light source having a wavelength range between about 180 nm and 450 nm is preferred. Acceptable light sources that emit ultraviolet energy include sunlight, solar lamps, LED lamps, carbon or xenon arc lamps, and mercury vapor lamps. More preferred examples of suitable light sources include electrode-type arc lamps or electrodeless-type microwave lamps with mercury vapor type or metal halide type bulbs that provide strong UV energy output in the ranges described above. .

The most preferred illumination is achieved by exposing a series of media to a high pressure mercury lamp having an intensity of about 100 W / inch to about 600 W / inch, thereby measuring about 20 to about 20 as measured using a suitable miniature radiometer. A UV energy of about 1500 to about 15000 mJ / cm ² is given with an exposure of 75 seconds. A more preferred energy output is about 3000 to about 8000 mJ / cm ² . It should be noted that intensity and energy measuring devices vary with the bandwidth they measure. When the preferred coating compositions described above are processed under these described irradiation conditions, the final coating provides a unique combination of properties that adequately protect the molded plastic article from environmental degradation and chemical degradation under severe exposure conditions. .

  In some embodiments of the present invention, the coating compositions described herein are used to form coated articles, particularly coated plastic articles such as those made using polycarbonate or polyester. A preferred embodiment provides a coated plastic lens, in particular to form a coated transparent plastic lens, such as an automotive front illuminating lens manufactured using polycarbonate. In this regard, referring to FIGS. 1 and 2, one aspect of a coated automotive front illumination lens is shown. The lens 11 exists in a non-vertical direction (eg, includes at least about 10% of the total outer surface area of the lens) and is designed in the hood line of the automobile 13 and thus is directly exposed by incident light from sunlight. 3 is an illustration of an “encapsulated illumination” lens that includes a large upper element 12. Such encapsulated lenses are beginning to become commonplace in current automobiles, and the challenge of designing a coating to provide UV protection to prevent yellowing due to sun exposure is shown. In a preferred embodiment of the present invention, the outer surface 14 of the lens 11 including the outer surface of the top element 12 is overcoated with the UV cured transparent coating composition of the present invention. Accordingly, a further aspect of the present invention provides such a coated vehicle front illumination lens and a vehicle including the same.

  The following examples are provided in order to facilitate a further understanding of the invention and some aspects thereof. It will be understood that these examples are illustrative and not limiting in any way.

Example 1:
Production of UV curable blend composition:
The components listed in Table 1 are blended using a known method, and the predetermined amount of the first and second urethane acrylate resins described above are added to the polyfunctional acrylate, photoinitiator, light stabilizer, and antioxidant. A UV curable resin blend composition was formed comprising an agent, and a flow improver. One or more inert solvents as described above can be included in the composition to change its flow characteristics.

Example 2:
Production of UV curable resin blend composition:
The components listed in Table 2 are blended using a known method, and the predetermined amounts of the first and second urethane acrylate resins described above are added to the polyfunctional acrylate, photoinitiator, light stabilizer, and antioxidant. A UV curable resin blend composition was formed comprising an agent, and a flow improver. One or more inert solvents as described above can be included in the composition to change its flow characteristics.

Example 3:
Production of coated plastic articles by flow coating:
Formulations of Example 1 or 2 were also prepared that also contained one or more inert solvents to achieve a specific gravity that would yield the desired film thickness range upon curing. A preferred specific gravity is in the range of less than about 0.975. A coating was applied by flow coating to an injection molded polycarbonate lens placed on a feature and the coating was applied only to the top and side surfaces of the lens. The wet coated lens was subjected to a brief atmosphere flush followed by convection heated air flush to evaporate the solvent. The wet coated lens is then exposed in air to irradiation with a standard mercury lamp of 240 W / cm at an intensity of about 450 mW / cm ² and a coated article having a coated dry film thickness of about 8-12 microns. Got.

Example 4: Production of a coated plastic article by spraying:
The formulation of Example 1 or 2 that also contained one or more inert solvents was applied to an injection molded polycarbonate lens by a spray method using a conventional spray gun mounted on a robot. A programmed spray pattern was used to achieve a stable coating of the coating and a cured dry film thickness in the range of 8-12 microns. The wet coated lens was subjected to heated convection air to evaporate the solvent and then irradiated in air with a 240 W / cm standard mercury lamp at an intensity of about 450 mW / cm ² .

  The use of the terms “a”, “an”, and “the” in the context of the description of the invention (especially in relation to the claims) is not indicated elsewhere or is apparent from the description. To the contrary, it should be interpreted as covering both the singular and plural. The description of a range of values herein is merely intended to serve as a concise way to individually indicate each separate value contained within that range, unless otherwise indicated herein. Each separate value is included in the specification as if it were individually indicated here. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by the description. The use of any and all examples or example terms (such as “such as”) given herein is merely intended to better elucidate the invention and, unless so claimed, It is not intended to limit the range. No language in the specification should be construed as indicating any non-claimed element as essential to the practice of the invention.

  While the invention has been illustrated and described in detail in the drawings and foregoing description, the same should be considered as illustrative and not restrictive, and only the preferred embodiments have been shown and described. It is understood that all changes and modifications within the spirit of this require protection. Further, all publications cited herein are hereby incorporated by reference in their entirety.

Claims (7)

A UV curable coating composition comprising:
(1) with a solvent;
(2) an aliphatic polyisocyanate component containing an iminooxadiazinedione, isocyanurate, uretdione, urethane, allophanate, biuret, or oxadiazinetrione group and at least one monobasic, hydroxyl-functional meta (acryl) A first aliphatic urethane acrylate resin formed by reaction with an alcohol component comprising a linear or branched alkyl ester of an acid;
The first aliphatic urethane acrylate has an average molecular weight of 800 to 2500;
Except for the solvent, the composition comprises 10% to 40% by weight of the first aliphatic urethane acrylate,
The first aliphatic urethane acrylate contains 3 to 5 polymerizable acrylate groups per molecule;
(3) a first aliphatic urethane acrylate resin comprising the structure of Formula II;

Wherein A ¹ , A ² , and A ³ are each a group that each contains a structure of Formula III:

(Wherein R ¹ , R ² , and R ³ in formula III may be the same or different, each being a linear aliphatic group having 2 to 12 carbon atoms, or 4 to 12 An alicyclic group having one carbon atom)
The first aliphatic urethane acrylate has an average molecular weight of 800-2500,
Except for the solvent, the composition comprises 10% to 50% by weight of the second aliphatic urethane acrylate,
The first aliphatic urethane acrylate contains 4-7 polymerizable acrylate groups per molecule,
The first aliphatic urethane acrylate and the second aliphatic urethane acrylate have a weight ratio of 1: 3 to 3: 1 (4) a first multifunctional acrylate;
The first multifunctional acrylate has an average molecular weight of 170 to 1000 on average;
Excluding the solvent, the composition comprises 5% to 55% by weight of the first multifunctional acrylate,
The first multifunctional acrylate comprises divinyl functionality;
(5) a second polyfunctional acrylate;
Except for the solvent, the composition comprises 5% to 55% by weight of the second multifunctional acrylate,
The second multifunctional acrylate comprises divinyl functionality;
(6) a photoinitiator selected from the group consisting of diphenylphosphine oxide, phenylglyoxylate, α-hydroxyketone, and bifunctional α-hydroxyketone and combinations thereof;
(7) a hindered amine light stabilizer;
(8) a UV absorber comprising benzotriazole or benzotriazine; and
(9) A UV curable coating composition comprising: an organic-inorganic hybrid material.   The composition of claim 1 wherein the polyisocyanate component comprises iminooxadiazinedione groups.   The composition of claim 1 wherein the polyisocyanate component comprises isocyanurate groups.   The composition of claim 1, wherein the polyisocyanate component comprises uretdione groups.   The composition of claim 1, wherein the polyisocyanate component comprises a urethane group.   The composition of claim 1 wherein the polyisocyanate component comprises allophanate groups.   The composition of claim 1 wherein the polyisocyanate component comprises a biuret group.

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