Field of the Invention

The present invention relates to antistatic laminates for coating display screens and optical lenses. More particularly, the present invention relates to coatings made of radiation curable liquid compositions for displays and lenses. The coatings have good liquid stability and curability, and are capable of forming a cured film (cured coating) which excels in antistatic properties, hardness, scratch resistance, and transparency when applied to various plastic substrates used to make display panels and lenses , including polycarbonate, polymethylmethacrylate, polystyrene, polyester, polyethyleneterephtalate, polyolefin, epoxy resin, melamine resin, triacetylcellulose resin, ABS resin, AS resin, norbomene resin, and the like.

Background of the invention In order to obtain good performance and safety in information communication equipment, such as displays, attempts have been made to develop radiation curable coating compositions used to prepare coatings with good scratch resistance and adhesion (hardcoat) or coatings with antistatic properties (antistatic film). These coatings are used form protective layers on the surface of the equipment. Radiation curable compositions can also be used to prepare coatings with antireflective properties. Typically, a multi-layer structure consisting of a low refractive index layer and a high refractive index layer have been used to provide such antireflective properties for optical articles.

In recent years, information communication equipment has evolved and is now used in a wide range of applications. As a result, further improvement of performance and versatility of hardcoats, antistatic coatings, and antireflective coatings has been of interest.

One important application for such coating materials is to form laminates on substrates, including, for example, display monitors (like flat screen computer and/or television monitors such as those utilizing technology discussed in, for example, U.S. Pat. Nos. 6,091 ,184 and 6,087,730, which are hereby incorporated by reference and made a part hereof), optical discs, touch screens, smart cards, flexible glass and the like. There is interest in the development of coated plastic substrates for, for instance, LCD (liquid crystal display, CRT displays, plasma display panel (PDP). Suitable substrates to be coated include organic substrates. Organic substrates are

preferably polymeric ("plastic") substrates, such as substrates comprising polyester, polynorbornene, polyethyleneterephtalate, polymethylmethacrylate, polycarbonate, polyethersulphone, polyimide, fluorene polyester (e.g. a polymer consisting essentially of repeating interpolymerized units derived from 9,9-bis(4-hydroxyphenyl)fluorene and isophthalic acid, terephthalic acid or mixtures thereof), cellulose (e.g. triacetate cellulose), and/or polyethernaphtalene. Particularly preferred substrates include polynorbornene substrates, fluorene polyester substrates, triacetate cellulose substrates, and polyimide substrates.

In the field of optical articles, such as plastic lenses, there is interest in preventing adhesion of dust due to static electricity and the decrease in light transmission due to reflection. In the field of display panels, there is a similar interest in preventing adhesion of dust due to static electricity and reflection of light on the screen. To help achieve these objectives, various radiation curable materials have been proposed because of their high degree of curability at room temperature. Attempts at producing antistatic coatings have involved several different composition formulations and additives. This is reflected in several publications including the following: (1 ) Japanese Patent Application Laid-open No. 47-34539, describing a composition containing a sulfonic acid monomer and a phosphoric acid monomer as ionic conductive components; (2) Japanese Patent Application Laid-open No. 60- 60166, describing a composition containing tin oxide particles, a polyfunctional acrylate, and a copolymer of methylmethacrylate and a polyether acrylate as major components; (3) Japanese Patent Application Laid-open No. 2000-143924, describing a curable liquid composition containing a reaction product of an alkoxysilane having a polymerizable unsaturated group in the molecule with metal oxide particles, a trifunctional acrylic compound, and a radiation polymerization promoter. The approaches disclosed in the above documents have not been entirely successful in creating coatings with the desired antistatic properties, hardness and long-term storage stability.

Summary of the invention

Objectives of the present invention include providing curable liquid compositions having good liquid stability and which are capable of forming a cured coating (cured film) with improved antistatic properties, hardness, scratch resistance, transparency on the surface of various substrates, and at the same time having a high refractive index and good curability when applied as thin films. The present invention

also relates to a process of making a coated substrate, an antistatic laminate and a display.

The above object can be achieved by a radiation curable composition, comprising: (A) nanoparticles of a metal oxide, metal nitride, metal sulfide, metal phosphide, metal carbide, metal boride, metal selenide or a mixture thereof; (B) a compound having at least two polymerizable unsaturated groups; (C) one or more solvents, wherein the solubility of said component (B) in said solvents is 60wt% or higher; wherein said composition maintains its liquid stability after aging at 54°C for 72 hours.

Another embodiment of the present invention is a radiation curable composition comprising:

(A) nanoparticles including as a major component an oxide of at least one element selected from the group consisting of antimony, indium, zinc, and tin;

(B) one or more compounds having at least two polymerizable unsaturated groups;

(C) one or more solvents wherein the solubility of said component (B) in said solvents is 60wt% or higher;. wherein said composition maintains its liquid stability after aging at 54 ⁰ C for 72 hours.

A further embodiment of the present invention is a radiation curable composition comprising: (A) 45 wt % to 90wt %, relative to the total weight of the composition, of a colloidal zinc-doped antimony oxide dispersion;

(B) 10wt% to 45wt%, relative to the total weight of the composition, of a urethane-containing (meth)acrylate compound having at least two polymerizable unsaturated groups; (C) 3wt% to 15wt%, relative to the total weight of the composition, of one or more solvents, wherein the solubility of said component (B) in said solvents is 60wt% or higher; wherein said composition maintains its liquid stability after aging at 54 ⁰ C for 72 hours.

- A -

A process of making a coating from the compositions is also provided. The compositions of the present invention are used to provide coatings for various applications, for instance in optical media, hardcoat and/or display, and as curable materials for use in stereolithography. Additional objects, advantages and features of the present invention are set forth in this specification, and in part will become apparent to those skilled in the art on examination of the following, or may be learned by practice of the invention. The invention disclosed in this application is not limited to any particular set of or combination of objects, advantages and features but may be adapted within the teachings set forth herein and the general knowledge to optimize and/or comply with particular design criteria.

Description of the invention

Definitions: -"Nanoparticles" refers to a particle mixture wherein the majority of particles in the mixture have a dimension below 1 μm. -"(Meth)acrylate" refers to "acrylate and/or methacrylate". -"Liquid stability" of a composition refers to a composition that does not form agglomeration, sediment or phase separation after accelerated aging at 54°C for 72 hours or after aging at 25°C for 6 months

- "Solid content" of a composition refers to the total content of metal nanoparticles (A), component (B), photoinitiator (D) and additives, if any, in the radiation curable composition. Solid content of the composition is determined gravimetrically by evaporation of volatiles from sample solutions in an aluminum weigh pan in a 120C oven for a period of one hour. Solid content is determined by measuring the weight difference between un-evaporated and evaporated sample. -"Inorganic content" refers to the total amount inorganic nanoparticles (A) in the solids portion of the radiation curable composition. The inorganic content percentage was determined empirically by calculating the ratio of inorganic solids (generally present as solid nanoparticles in a nanoparticle dispersion) to total solids in the composition and multiplying by 100%.

The invention relates, inter alia, to a radiation curable composition comprising:

(A) nanoparticles of a metal oxide, metal nitride, metal sulfide, metal

phosphide, metal carbide, metal boride, metal selenide or a mixture thereof;

(B) a compound having at least two polymerizable unsaturated groups

(C) one or more solvents, wherein the solubility of said component (B) in said solvents is 60wt% or higher; wherein said composition maintains its liquid stability after aging at 54 ⁰ C for 72 hours.

Component (A) - Nanoparticles

Component (A) used in the present invention comprises nanoparticles of a metal oxide, metal nitride, metal sulfide, metal phosphide, metal carbide, metal boride, metal selenide or a mixture thereof. Suitable metals that can be used in these compounds include antimony, zinc, tin, zirconium, titanium, indium, aluminum and gallium. These nanoparticles are electro-conductive nanoparticles. In one embodiment, these nanoparticles contain, as a major component, an oxide of at least one element selected from the group consisting of indium, antimony, zinc, and tin, in order to achieve the desired conductivity and transparency of the cured film. "Major component" in this context means either that the component (A) is made entirely of one of these oxides or that component (A) is a metal oxide (A1 ) doped with another metal oxide (A2) (for example, antimony oxide doped with zinc oxide), and the amount of component (A1 ) is at least 90% by weight.

Specific examples of the oxide nanoparticles used as the component (A) include tin-doped indium oxide (ITO), antimony-doped tin oxide (ATO), fluorine- doped tin oxide (FTO), phosphorus-doped tin oxide (PTO), zinc antimonate (AZO), indium-doped zinc oxide (IZO), and zinc oxide. Among them, antimony-doped tin oxide (ATO) and tin-doped indium oxide (ITO) are currently preferred. These particles may be used either individually or in combination of two or more.The same combinations can also be used in the case of nitride particles, sulfide particles, phosphide particles, carbide particles, boride particles, and selenides.

Examples of commercially available oxide particles that can be used alone or in combination for component (A) are T- 1 (ITO) (manufactured by Mitsubishi Materials Corporation), Passtran (ITO, ATO) (manufactured by Mitsui Mining & Smelting Co., Ltd.), SN-100P (ATO) (manufactured by lshihara Sangyo Kaisha, Ltd.), NanoTek ITO (manufactured by C.I. Kasei Co., Ltd.), ATO, FTO (manufactured by Nissan Chemical Industries, Ltd.) and the like. The nanoparticles used as component (A) may be used in a

powdered state or they may be dispersed in a solvent. It is preferable to use the nanoparticles in a dispersion state in a solvent, since uniform dispersibility can be more easily obtained. The weight percentage of solid nanoparticles, relative to the combined weight of particles and solvent in the dispersion is preferably 30wt% to 70wt%, more preferably from 35wt% to 60wt%Examples of commercially available products in which oxide particles used as the component (A) are dispersed in an organic solvent include the following: MTC Filler 12867 (aqueous dispersion of ATO), and MHI Filler #8954MS (methyl ethyl ketone dispersion of ATO), manufactured by Mikuni Color, Ltd.); SN-100D (aqueous dispersion of ATO), SNS-101 (isopropyl alcohol dispersion of ATO), SNS-10B (isobutanol dispersion of ATO), SNS-10M (methyl ethyl ketone dispersion of ATO), FSS-10M (isopropyl alcohol dispersion of ATO), manufactured by lshihara Sangyo Kaisha, Ltd.; Celnax CX-Z401 M (methanol dispersion of zinc antimonate), Celnax CX- Z200IP (isopropyl alcohol dispersion of zinc antimonate), Celnax CX-Z641 (Methanol sol of zinc antimonate), Suncolloid AMT130S or AMT330S (methanol dispersion of antimony pentoxide) (manufactured by Nissan Chemical Industries, Ltd.); aqueous dispersion, methanol dispersion, isopropyl alcohol dispersion, methyl ethyl ketone dispersion, and toluene dispersion of Passtran type-A (ITO) (manufactured by Mitsui Mining and Smelting Co., Ltd.), and the like.

Particularly preferred in the practice of the present invention are colloidal dispersions of metal oxides such as Celnax CX-Z401 M (methanol dispersion of zinc antimonate), Celnax CX-Z641 (Methanol sol of antimony oxide), and the like.

In one embodiment, the weight percentage of the colloidal dispersion containing metal nanoparticles is from 45wt% to 90wt%, relative to the total weight of the radiation curable composition. In another embodiment, the weight percentage of the colloidal dispersion is from 60wt% to 85wt%, relative to the total weight of the radiation curable composition.

Component (B) - Compound with Polvmerizable UnsaturatedGroups

Component (B) used in the present invention comprises a compound having at least two polymerizable unsaturated groups. A cured product having improved scratch resistance and organic solvent resistance can be obtained by using compounds of this type for component (B). Without being bound by theory, Component (B) is believed to function as a surface treatment agent for the metal nanoparticles of component (A) and to improve the dispersibility of the metal nanoparticles in the radiation curable composition while at the same time improving film formability and

transparency of the cured film of the curable liquid composition.

Specific examples of compounds that can be used for component (B) include (meth)acrylate compounds and vinyl compounds. Examples of (meth)acrylates compounds include trimethylolpropane tri(meth)acrylate, alkoxylated trimethylolpropane tri(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, glycerol tri(meth)acrylate, tris(2-hydroxyethyl)isocyanurate tri(meth)acrylate, ethylene glycol di(meth)acrylate, 1 ,3- butanediol di(meth)acrylate, 1 ,4-butanediol di(meth)acrylate, 1 ,6-hexanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, dipropylene glycol di(meth)acrylate, bis(2- hydroxyethyl)isocyanurate di(meth)acrylate, tricyclodecanediyldimethanol di(meth)acrylate, poly(meth)acrylates of ethylene oxide or propylene oxide addition product of a starting alcohol used to produce these compounds, oligoester (meth)acrylates having at least two (meth)acryloyl groups in the molecule, oligoether (meth)acrylates, oligourethane (meth)acrylates, oligoepoxy (meth)acrylates, and the like.

Among the (meth)acryiate compounds, hydroxy-containing multifunctional (meth)acrylates such as pentaerythritol tri(meth)acrylate, dipentaerythritol hexa(meth)acrylate, dipentaerythritol penta(meth)acrylatepentaerythritol tetra(meth)acrylate, trimethylolpropane multi (meth)acrylates such as trimethylolpropane tri(meth)acrylate, alkoxylated trimethylolpropane tri(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate, and isocyanurate multi(meth)acrylates such as tris(2-hydroxyethyl)isocyanurate tri(meth)acrylate, bis(2-hydroxyethyl)isocyanurate di(meth)acrylate, melamine pentaacrylates, and tricyclodecanedimethanol di(meth)acrylate are preferred.

Examples of preferred vinyl compounds that may be used as component (B) includes divinylbenzene, ethylene glycol divinyl ether, diethylene glycol divinyl ether, triethylene glycol divinyl ether, and the like. Component (B) can also be urethane-containing multi(meth)acrylates, a product of the reaction between polyisocyanates and reactive (meth)acrylate monomers.

Suitable polyisocyanates used as reactants in the production of such urethane-containing multi(meth)acrylates include diisocyanates, such as 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 1 ,3-xylylene diisocyanate, 1 ,4-xylylene

diisocyanate, 1 ,5-naphthalene diisocyanate, m-phenylene diisocyanate, p-phenylene diisocyanate, 3,3'-dimethyl-4,4'-diphenylmethane diisocyanate, 4,4'-diphenylmethane diisocyanate, 3,3'-dimethylphenylene diisocyanate, 4,4'-biphenylene diisocyanate, 6- isopropyl-1 ,3-phenyl diisocyanate, 4-diphenylpropane diisocyanate, lysine diisocyanate, hydrogenated diphenylmethane diisocyanate, hydrogenated xylylene diisocyanate, tetramethylxylylene diisocyanate, 1 ,6-hexane diisocyanate, isophorone diisocyanate, methylenebis(4-cyclohexyl) isocyanate, 2,2,4-trimethylhexamethylene diisocyanate, bis(2- isocyanate-ethyl) fumarate, and 2,5 (or θ^bis^socyanatemethyO-bicycloP^.IJheptane. Among these diisocyanates, 2,4-tolylene diisocyanate, isophorone diisocyanate, xylylene diisocyanate, and methylenebis(4-cyclohexylisocyanate) are desired. These diisocyanate compounds can be used either individually or as combinations of two or more.

Suitable reactive (meth)acrylate monomers used in the production of such urethane-containing multi(meth)acrylates include hydroxy-, mercapto- or amine- functional acrylate monomers. Examples of suitable hydroxy, mercapto or amine functional acrylate compounds include 2-hydroxyethyl (meth)acrylate, 2-hydroxy butyl (meth)acrylate), hydroxy propyl (meth)acrylate, pentaerythritol triacrylate, dipentaerythritol pentaacrylate, methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, butyl (meth)acrylate, amyl (meth)acrylate, isobutyl (meth)acrylate, t-butyl (meth)acrylate, pentyl (meth)acrylate, isoamyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, octyl (meth)acrylate, isooctyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, nonyl (meth)acrylate, decyl (meth)acrylate, isodecyl (meth)acrylate, undecyl (meth)acrylate, dodecyl (meth)acrylate, lauryl (meth)acrylate, stearyl (meth)acrylate, isostearyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, butoxyethyl (meth)acrylate, ethoxydiethylene glycol (meth)acrylate, benzyl(meth)acrylate, phenoxyethyl(meth)acrylate, polyethylene glycol mono(meth)acrylate, polypropylene glycol mono(meth)acrylate, methoxyethylene glycol (meth)acrylate, ethoxyethyl (meth)acrylate, methoxypolyethylene glycol (meth)acrylate, methoxypolypropylene glycol (meth)acrylate, diacetone(meth)acrylamide, isobutoxymethyl(meth)acrylamide, N,N-dimethyl(meth)acrylamide, t- octyl(meth)acrylamide, dimethylaminoethyl (meth)acrylate, diethylaminoethyl

(meth)acrylate, 7-amino-3,7-dimethyloctyl (meth)acrylate thioethyl acrylate, aminoethyl acrylate and the like.

Examples of urethane-containing multi(meth)acrylates include reaction products of reactive group terminated oligomers or polymers. Examples of reactive group terminated oligomers or polymers include "polyols" that are used as oligomeric/polymeric

backbones in the urethane-multiacrylate compound. Examples of suitable polyols to be used as backbones in the additional oligomer are polyether polyols, polyester polyols, polycarbonate polyols, polycaprolactone polyols, acrylic polyols, and the like. These polyols may be used either individually or in combinations of two or more. There are no specific limitations to the manner of polymerization of the structural units in these polyols. Any of random polymerization, block polymerization, or graft polymerization is acceptable. Examples of suitable polyols, polyisocyanates and other hydroxylgroup-containing (meth)acrylates are disclosed in WO 00/18696 which is hereby incorporated by reference. Component (B) is added to the radiation curable composition of the present invention in an amount of 1 % to 65wt %, relative to the total weight of the composition, preferably 10wt% to 55wt%, relative to the total weight of the composition, more preferably, 15wt% to 45wt%, relative to the total weight of the composition. The component (B) may comprise any one of the compounds listed above or may comprise a combination of two or more such compounds. Component (B) is used in an amount of 25-65 parts by weight for 100 parts by weight of the total amount of the components (A) and (B) in order to maintain antistatic property and high refractive index for the cured coating as well as the liquid stability of the uncured composition.

Component (C) - Solvent

Component (C) used in the present invention is a solvent in which component (B) has a solubility of 50wt% or higher; the solubility of component (B) in the component (C) solvent can also be 60wt% or higher, or 80 % or higher. Solvent (C) can also be a solvent in which the component (B) is infinitely soluble. Solvent (C) can be the same type of solvent used in the dispersion of the component (A) nanoparticles if, as described above, component (A) takes the form of a colloidal dispersion of nanoparticles. "Solubility" is defined as saturation solubility of the component (B) at 25 ⁰ C. In more detail, the solubility is determined by measuring the solid content of the component (B) in a solution consisting of the component (B) and the solvent. There are no specific limitations regarding the type of solvent that may be used. In general, however, it is preferable to use a solvent having a boiling point of 200 ⁰ C or less at atmospheric pressure. The solvent may be used either individually or in combination with one or more additional solvents.

The amount of one or more solvents (component (C)) in the radiation curable composition of the present invention is 3wt% to 15wt%, relative to the total

weight of the composition; more preferably, 4wt% to 10wt%, relative to the total weight of the composition. These weight percentages refer to component (C) alone and are independent of any solvent present in the colloidal dispersion of the component (A) nanoparticles, in the event such a colloidal dispersion is used as described above. Examples of suitable solvents that may be used for component (C) are alcohols such as methanol, ethanol, 1-propanol, isopropyl alcohol, isobutanol, n- butanol, tert-butanol, ethoxyethanol, butoxyethanol, diethylene glycol monoethyl ether, and diacetone alcohol; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, and methyl amyl ketone; ethers such as dibutyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, and propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate; esters such as ethyl acetate, butyl acetate, ethyl lactate, methyl acetoacetoate, and ethyl acetoacetate; hydrocarbons such as toluene and xylene; amides such as N, N- dimethylformamide, N,N-dimethylacetamide, and N-methylpyrrolidone, other similar solvents and mixtures of the foregoing.

It will be understood that other components in addition to components (A) through (C) may also be used in the composition of the present invention. Examples of other components typically used in the composition include photoinitiators and other additives.

Photoinitiators

The radiation curable liquid composition of the present invention is preferably cured by exposing it to radiation, such as visible rays, ultraviolet rays, deep ultraviolet rays, X-rays, electron beams, α-rays, β-rays, γ-rays, and the like. In order to further increase the cure speed, a photoinitiator may be added.

The photoinitiators are desirably free-radical photoinitiators. Free- radical photoinitiators include benzoin derivatives, methyloylbenzoin and 4-benzoyl-1 ,3- dioxolane derivatives, benzilketals, α,α-dialkoxyacetophenones, α-hydroxy alkylphenones, α-aminoalkylphenones, acylphosphine oxides, bisacylphosphine oxides, acylphosphine sulphides, halogenated acetophenone derivatives, and the like. Commercial examples are lrgacure 651 (benzildimethyl ketal or 2,2-dimethoxy-i ,2- diphenylethanone, Ciba-Geigy), lrgacure 184 (1-hydroxy-cyclohexyl-phenyl ketone as the active component, Ciba-Geigy), Darocur 1173 (2-hydroxy-2-methyl-1- phenylpropan-1-one as the active component, Ciba-Geigy), lrgacure 907 (2-methyl-1-

[4-(methylthio)phenyl]-2-morpholino propan-1-one, Ciba-Geigy), lrgacure 369 (2- benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butan-1-one as the active component, Ciba-Geigy), Esacure KIP 150 (poly {2-hydroxy-2-methyl-1-[4-(1- methylvinyl)phenyl]propan-1-one}, Fratelli Lamberti), Esacure KIP 100 F (blend of poly {2-hydroxy-2-methyl-1-[4-(1-methylvinyl)phenyl]propan-1-one} and 2-hydroxy-2-methyl- 1-phenyl-propan-1-one, Fratelli Lamberti), Esacure KTO 46 (blend of poly {2-hydroxy-2- methyl-1 -[4-(1 -methylvinyl)phenyl]propan-1 -one}, 2,4,6- trimethylbenzoyldiphenylphosphine oxide and methylbenzophenone derivatives, Fratelli Lamberti), acylphosphine oxides such as Lucirin TPO (2,4,6-trimethylbenzoyl diphenyl phosphine oxide, BASF), lrgacure 819 (bis (2,4,6-trimethylbenzoyl)-phenyl-phosphine- oxide, Ciba-Geigy), lrgacure 1700 (25:75% blend of bis (2,6-dimethoxybenzoyl)2,4,4- trimethylpentyl phosphine oxide and 2-hydroxy-2-methyl-1-phenyl-propan-1-one, Ciba- Geigy), and the like.

Other examples of suitable photoinitiators are aromatic ketones such as benzophenone, xanthone, derivatives of benzophenone (e.g. chlorobenzophenone), blends of benzophenone and benzophenone derivatives (e.g. Photocure 81 , a 50/50 blend of 4-methyl-benzophenone and benzophenone), Michler's Ketone, Ethyl Michler's Ketone, thioxanthone and other xanthone derivatives like Quantacure ITX (isopropyl thioxanthone), benzil, anthraquinones (e.g. 2-ethyl anthraquinone), coumarin, and the like. Chemical derivatives and combinations of these photoinitiators can also be used.

Other types of photoinitiators that may be used in carrying out the present invention are photoinitiators which generally are used together with an amine synergist. Preferably, the amine synergist is chosen from the group consisting of a monomer tertiary amine compound, an oligomer (polymer) tertiary amine compound, a polymerizable amino acrylate compound, a polymerized amino acrylate compound and mixtures thereof. The amine-synergist may include tertiary amine compounds, such as alkanol-dialkylamines (e.g., ethanol-diethylamine), alkyldialkanolamines (e.g. methyldiethanolamine), trialkanolamines (e.g. triethanolamine), and ethylenically unsaturated amine-functional compounds including amine-functional polymer compounds, copolymerizable amine acrylates, and the like. The ethylenically unsaturated amine compounds may also include dialkylamino alkyl(meth)acrylates (e.g., diethylaminoethylacrylate) or N-morpholinoalkyl-(meth)acrylates (e.g., N- morpholinoethyl-acrylate). The photoinitiator may also be an oligomeric photoinitiator.

Examples of an oligomeric photoinitiators include oligomers of 2-hydroxy-2-methyl-1- phenyl(4-(1-methylvinyl)phenyl)-1-propanone as well as 2-hydroxy-2-methyl-1-phenyl- 1-propanone. The oligomeric photoinitiator can include Esacure KIP 100F, available from Lamberti Corporation. In the radiation curable composition of the present invention, the photoinitiator is added in an amount of 0.1wt% to 15wt%, relative to the total weight of the composition, preferably 0.5wt% to 10wt%, relative to the total weight of the composition. The photoinitiator may be used either individually or in combination with other photoinitiators.

Additives

Antioxidants, antistatic agents, UV absorbers, light stabilizers, heat polymerization inhibitors, leveling agents, surfactants, lubricants, as well as other additives, may be added to the composition of the present invention. Examples of antioxidants include Irganox 1010, 1035, 1076, 1222 manufactured by Ciba Specialty Chemicals Co., Ltd.), and the like. Examples of UV absorbers include Tinuvin P234, 320, 326, 327, 328, 213, 329 (manufactured by Ciba Specialty Chemicals Co., Ltd.), Seesorb 102, 103, 501 , 202, 712, (manufactured by Shipro Kasei Kaisha, Ltd.), and the like. Examples of light stabilizers include Tinuvin 292, 144, 622LD (manufactured by Ciba Specialty Chemicals Co., Ltd.), Sanol LS770, LS440 (manufactured by Sankyo Co., Ltd.), Sumisorb TM-061 (manufactured by Sumitomo Chemical Co., Ltd.), and the like. Examples of antistatic additives include Larostat additives such as Larostat HTS905 (manufactured by BASF corp.), Crodastat additives such as Crodastat 1450 (manufactured by Croda Inc.), and the like. The amount of the additives used in the radiation curable composition can be in the range, for example, of from 0.01 wt% to about 7.0 wt%; more preferably, the amount of additives can be from 0.1 wt% to 5w%; still more preferably, the amount of additives can be from 0.5wt% to 4 wt%, relative to the total weight of the composition.

Cured Coating (Cured Film)

The cured film of the present invention can be obtained by applying the radiation curable liquid composition onto an uncoated or a previously coated substrate and drying said composition; the dried composition is then cured by applying radiation.

In one embodiment, the radiation curable composition of the present invention, when cured, has a surface resistivity of 1 x 10 ¹² Ω/ square or less, preferably 1 x 10 ⁹ Ω/ square or less, and still more preferably 1 x 10 ⁸ Ω/ square or less at a film thickness of 4μm or less when measured at 25°C and 50% Relative Humidity. The lower the surface resistivity, the higher the conductivity of the film; a high electro- conductive film can prevent the adhesion of dust onto it surface. 50% Relative Humidity refers to the % of humidity that the air can hold up at a certain temperature.

In another embodiment, the radiation curable composition of the present invention, when cured, has a surface resistivity of 1 x 10 ¹² Ω/ square or less, preferably 1 x 10 ⁹ Ω/ square or less, and still more preferably 1 x 10 ⁸ Ω/ square or less at a film thickness of 4μm or less, when measured at 25°C after exposure to 0% humidity for a period of 21 days. 0% humidity refers to the humidity in a standard laboratory dessicator equipped with self-sealing lid and Drierite® brand anhydrous calcium sulfate with cobalt chloride humidity indicator (available from VWR International). Internal dessicant humidity/temperature was monitored using a BYK Gardner Model 201 humidity/temperature monitor. More detail descriptions are in the test method portion.

If the surface resistivity exceeds 1 x 10 ¹² Ω/ square, antistatic properties may be insufficient, whereby dust may easily adhere, or the adhering dust may not be easily removed.

There are no specific limitations to the method of applying the composition. For example, any suitable method, such as a roll coating, spray-coating, flow coating, dipping, screen printing, or ink jet printing may be used.

There are no specific limitations to the radiation source that may be used to cure the composition provided that the applied composition can be cured in a relatively short period of time.

Examples of potential sources of visible rays include sunlight, lamp, fluorescent lamp, and laser. Potential sources of ultraviolet rays include mercury lamp, halide lamp, laser, and the like. Suitable sources of electron beams include a method of utilizing thermoelectrons produced by a commercially available tungsten filament, a cold cathode method which causes electron beams to be generated by applying a high voltage pulse to a metal, a secondary electron method which utilizes secondary electrons produced by the collision of ionized gaseous molecules and a metal electrode, and the like.

Potential sources of α-rays, β-rays, and γ-rays include fissionable materials such as ⁶⁰ Co. The source of γ-rays can include a vacuum tube which causes accelerated electrons to collide against an anode. The radiation may be applied by any one of the methods described above or in combinations of two or more such methods The thickness of the cured film is preferably 0.1 μm -20μm. In applications such as a touch panel or a CRT in which scratch resistance of the outermost surface is important, the thickness of the cured film is preferably 2μm -15 μm. In the case of using the cured film as an antistatic film for an optical film or lens, the thickness of the cured film is preferably 0.1 μm -10μm. Transparency is an important characteristic of the cured film when it is used as an optical film. In an embodiment of the present invention, the average total light transmission percentage at 400nm-700nm of the composition, when cured, is 80% or greater at a cured film thickness of 4μm or less. More preferably, the total light transmission percentage at 400nm-700nm of the composition, when cured, is 83% or greater at a cured film thickness of 4μm or less.

The composition of the present invention, when cured, provides a cured film with a high refractive index. In one embodiment, the cured film has a refractive index of 1.60 or higher, preferably 1.60 to 2.0, more preferably 1.65 to 1.9. Thus, the composition may be used as a high refractive index layer in a multiple layer anti reflective film comprised of high and low refractive index layers.

The composition of the present invention, when cured, exhibits an average haze percentage (which represents the amount of visible light scattered by the cured film) at 400nm-700nm of 8 % or less at a cured film thickness of 4μm or less. Preferably, the haze percentage at 400nm-700nm is 4 % or less at a cured film thickness of 4μm or less.

The composition of the present invention, when cured, provides a cured film with good surface hardness and abrasion resistance. These properties are characterized by the pencil test for film hardness and steel wool resistance test. In one embodiment, the composition, when cured, has a pencil hardness of F or greater at a cured film thickness of 4μm or less; preferably H or greater, more preferably, 2H or greater.

In one embodiment, the composition of the present invention, when cured, has a steel wool resistance of grade 3 to grade 5; preferably grade 4 to grade 5 The cured film of the present invention demonstrates a Crosshatch

adhesion to hardcoated or uncoated polyester (PET), triacetate cellulose (TAC) or polycarbonate (PC) of 4B to 5B.

The viscosity of the composition of the present invention at 25 ⁰ C prior to curing is usually 1-20,000 mPa-s, preferably 1-1 ,000 mPa-s. The radiation curable composition of the present invention maintains its liquid stability after aging at 54 ⁰ C for 72 hours (accelerated aging), or after aging at 25°C for 6 months.

The radiation curable composition of the present invention exhibits fast curability. The UV cure dose used to polymerize 95% of the unsaturated acrylate groups in the composition is less than 10J/cm ² , preferably less than 9J/cm ² .

All the tests used to evaluate the above mentioned properties are set forth in the test methods portion.

Substrates A substrate made from metal, ceramics, glass, plastic, wood, slate, or the like may be used without specific limitations as a substrate onto which the cured film of the present invention is applied. For materials used in industrial applicability of radiation curability, it is preferable to apply the cured film to a film-type or fiber-type substrate. A plastic film or a plastic sheet is a particularly preferable material, particularly when the composition is to be used as a coating for display panels and optical lenses. Examples of plastic substrates that may be used in the practice of the invention include polycarbonate, polymethylmethacrylate, polyethyleneterephtalate, polystyrene/polymethylmethacrylate copolymer, polystyrene, polyester, polyolefin, triacetylcellulose resin, diallylcarbonate of diethylene glycol (CR-39), ABS resin, AS resin, polyamide, epoxy resin, melamine resin, cyclic polyolefin resin (norbornene resin, for example), and the like.

The cured film of the present invention is useful as a hardcoat for display panels because of its excellent scratch resistance and adhesion. Since the cured film has excellent antistatic properties, the cured film is suitably applied to various substrates such as film-type, sheet-type, or lens-type substrates as an antistatic film.

Examples of the cured film of the present invention include, but not limited to, application as a hardcoat for preventing scratches on the surface of the product or for preventing adhesion of dust due to static electricity, such as a protective

film for touch panels, transfer foil, hard coat for optical disks, film for automotive windows, antistatic protective film for lenses, and surface protective film for cosmetics containers; the cured film of the present invention can also be used as an antistatic/antireflective film for various display panels such as CRTs, liquid crystal display panels, plasma display panels, and electroluminescence display panels; it can also be used as an antistatic/ antireflective film for plastic lenses, polarization film, and solar battery panel.

One method of providing antireflective properties to an optical article is to form a multi-layer structure consisting of a low refractive index layer and a high refractive index layer on a substrate or a substrate to which a hardcoat treatment has previously been applied. The cured film of the present invention is useful as a layer structure which is antistatic and at the same time has a high refractive index. Consequently, an antistatic laminate having antireflection properties can be produced by using the cured film of the present invention in combination with a film having a refractive index lower than that of the cured film.

Antistatic laminate:

An antistatic laminate can include a coating layer having a thickness of 0.05 μm -0.20μm and a refractive index of 1.30-1.48 as a low refractive index layer formed on the cured film of the present invention. In this case, the cured film of the present invention acts at the same time as an antistatic layer and a high refractive index layer. Another example of an antistatic laminate including a laminate having a coating layer with a thickness of 0.05 μm -0.20μm and a refractive index of 1.60-2.20 as a high refractive index layer formed on the cured film of the present invention, and a coat layer having a thickness of 0.05 μm -0.20μm and a refractive index of 1.30-1.48 as a low refractive index layer formed on the high refractive index layer.

In a preferred form, the antistatic laminate of the present invention is composed of a substrate, a hardcoat layer, an antistatic layer having high refractive index and a low refractive index layer; this antistatic layer was made from the composition of the present invention. This laminate also exhibits antireflective property (antistatic/antireflective laminate).

In the production of the antistatic laminate, in order to provide other functions such as a non-glare effect, a selective light-absorption effect, weatherability, durability, or transferability, a layer including light scattering particles with a thickness of 1 μm or more, a layer including dyes, a layer including UV absorbers, an adhesive

layer, or an adhesive layer and a delamination layer may be added. Moreover, the components which provide such functions may be added to the antistatic curable composition of the present invention.

The antistatic laminate of the present invention is also suitable for use as a hardcoat material for preventing stains or cracks (scratches) on plastic optical parts, touch panels, film-type liquid crystal elements, and the like. It may also be used to provide such a protective function when applied to plastic casings, plastic containers, or flooring materials, wall materials, and artificial marble used for an architectural interior finish; it can also be used as an adhesive or a sealing material for various substrates; as a vehicle for printing ink; or the like.

The present invention relates to an antistatic laminate comprising a layer of a cured film obtained by curing a radiation-curable composition comprising: (A) nanoparticles of a metal oxide, metal nitride, metal sulfide, metal phosphide, metal carbide, metal boride, metal selenide or a mixture thereof; (B) a compound having at least two polymerizable unsaturated groups;

(C) one or more solvents, wherein the solubility of said component (B) in said solvents is 60wt% or higher; wherein said composition maintains its liquid stability after aging at 54°C for 72 hours. In one embodiment, the antistatic laminate of the present invention, has a surface resistivity of 1 x 10 ⁷ Ω/ square to 1 x 10 ¹⁰ Ω/ square, preferably 2 x 10 ⁷ Ω/ square to 5 x 10 ⁹ Ω/ square, and still more preferably 3χ 10 ⁷ Ω/ square to 1x 10 ⁹ , when measured at 25°C and 50% Relative Humidity.

In one embodiment, the antistatic laminate of the present invention, has a surface resistivity of 1 x 10 ⁷ Ω/ square to 1 x 10 ¹⁰ Ω/ square, preferably 2 x 10 ⁷ Ω/ square to 5 x 10 ⁹ Ω/ square, and still more preferably 3χ 10 ⁷ Ω/ square to 1x 10 ⁹ , when measured at 25°C and 0% Relative Humidity.

The antistatic laminate of the present invention exhibits an average haze percentage at 400nm-700nm of 8 % or less. Preferably, the haze percentage at 400nm-700nm is 4 % or less. The antistatic laminate of the present invention has an average total light transmission percentage at 400nm-700nm of 70% to 100%, preferably 75% to 97%, more preferably, 80% to 93%.

In one embodiment, the antistatic laminate of the present invention, without being exposed to a caustic solution, has a reflectance percentage at 340nm- 700nm of 0%-5%, preferably 0.1%-3%, more preferably 0.2%-2%. In another

embodiment, the antistatic laminate of the present invention has a reflectance percentage at 340nm-700nm of 0.1%-7%, preferably 0.2%-5%, more preferably 0.3%- 3%, when exposed to a caustic solution for 30 minutes. Caustic solution refers to an aqueous solution of NaOH 5%. In a preferred form, when a drop of distilled water is applied onto the surface of the antistatic laminate of the present invention, the contact angle formed between this surface and the tangent surface of the drop of water is 85 degree to 160 degree, preferably 90 degree to 155 degree, more preferably 95 degree to 150 degree.

The antistatic laminate of the present invention has a steel wool resistance of grade 3 to grade 5; preferably grade 4 to grade 5, measured by ASTM D3359.

The present invention also relates to a display comprising: a) a substrate; b) a hardcoat layer; c) an antistatic coating on said hardcoat layer, said antistatic coating is obtained by curing a radiation-curable composition comprising: (A) nanoparticles of a metal oxide, metal nitride, metal sulfide, metal phosphide, metal carbide, metal boride, metal selenide or a mixture thereof; (B) a compound having at least two polymerizable unsaturated groups;

(C) one or more solvents, wherein the solubility of said component (B) in said solvents is 60wt% or higher; wherein said composition maintains its liquid stability after aging at 54°C for 72 hours ; and d) a low refractive index coating..

The present invention also relates to a process for preparing a coated substrate having an antistatic coating comprising:

Applying onto the surface of said coated substrate a radiation-curable composition comprising:

(A) nanoparticles of a metal oxide, metal nitride, metal sulfide, metal phosphide, metal carbide, metal boride, metal selenide or a mixture thereof;

(B) a compound having at least two polymerizable unsaturated groups;

(C) one or more solvents, wherein the solubility of said component (B) in said solvents is 60wt% or higher.;

wherein said composition maintains its liquid stability after aging at 54°C for 72 hours.

Examples The following examples are given as particular embodiments of the invention and to demonstrate the practice and advantages thereof. It is to be understood that the examples are given by way of illustration and are not intended to limit the specification or the claims that follow in any manner.

In the following synthesis examples, "part" and "%" respectively refer to "part by weight" and "wt%" unless otherwise indicated.

Synthesis of compound B-5 (urethane-containinq multi(meth)acrylate) in Example 4:

57.57 parts 2-hydroxyethyl acrylate of were added dropwise to a solution of 42.33 parts toluene diisocyanate (TDI80 available from Lyondell: 80% 2,4 isomer, 20% 2,6 isomer), 0.05 parts butylated hydroxy toluene (BHT) and 0.05 parts of dibutyltin dilaurate in a vessel equipped with a stirrer at 4O ⁰ C over one hour in dry air reaction vessel atmosphere. The mixture was stirred at 5O ⁰ C for three hours. The residual isocyanate content in the reaction product (reactive surface treatment agent) in the reaction solution was measured titrimetrically and found to be less than 0.1 wt% NCO.

Synthesis of compound B-4 (reactive surface treatment agent) in Comparative Example 5:

20.6 parts of isophorone diisocyanate were added dropwise to a solution of 7.8 parts of γ-mercaptopropyltrimethoxysilane and 0.2 parts of dibutyltin dilaurate in a vessel equipped with a stirrer at 5O ⁰ C over one hour in dry air. The mixture was stirred at 6O ⁰ C for three hours.

After the addition of 71.4 parts of pentaerythritol triacrylate dropwise at 3O ⁰ C for one hour, the mixture was stirred at 6O ⁰ C for three hours to obtain a reaction solution.

The residual isocyanate content in the reaction product (reactive surface treatment agent) in the reaction solution was measured by FT-IR and found to be 0.1 wt% or less. This indicates that each reaction was completed almost quantitatively. It was confirmed that the reactive surface treatment agent had a

thiourethane bond, a urethane bond, an alkoxysilyl group, and a polymerizable unsaturated group.

Synthesis of component A-3 (reactive nanomethanol sol) in Comparative Example 6: A vessel equipped with a stirrer was charged with 82.51 parts of a dispersion liquid of Nanosilica particles ("MT-ST" manufactured by Nissan Chemical., dispersion solvent: methanol, content of Nanosilica : 30wt%, solid content: 30 wt%, average particle diameter: 12 nm,), 7.82 parts of the reactive surface treatment agent Int-12A, the synthesis of which was disclosed in European application publication 1479738, which is herein incorporated by reference. , and 0.15 parts of p- methoxyphenol. The mixture was heated at 55 ⁰ C with stirring. After three hours, 1.24 parts of methyl trimethoxy silane was added. The mixture was maintained at 55 ⁰ C with stirring. After one hour, 0.83 parts of trimethyl orthoformate was added. The mixture was heated for a further one hour at 55 ⁰ C with stirring to obtain reactive particles.

Examples 1-4 and Comparative Examples 5-6: Preparation of Examples and Comparative Examples: Examples 1-4 and Comparative Examples 5-6 were prepared by: a. Admixing components B, C ₁ and D b. Filtering the above mixture through 1 μm-encapsulated depth filter, available from Millipore, Inc. c. Mixing the filtered mixture with component A.

The components and their relative amounts used to prepare the compositions of Examples 1-4 and Comparative Examples 5-6 are shown in Table 1 below. Test properties for these examples are set forth in Table 2.

Table 1

The components shown in Table 1 are as follows.

A-1 : Colloidal Antimony Pentoxide Methanol dispersion (Celnax Z401 M available from

Nissan Chemical Ind.): 40wt% of Zinc-doped Antimony oxide particles, relative to the combined weight of particles and methanol. A-2: Colloidal Antimony Pentoxide Methanol dispersion (Celnax Z641 M available from

Nissan Chemical Ind.): 60wt% of Zinc-doped Antimony oxide particles, relative to the combined weight of particles and methanol. A-3: See above description of synthesis. A-4: Colloidal Antimony Pentoxide Methanol dispersion (AMT130S available from

Nissan Chemical Ind.): 31wt% of antimony pentoxide particles, relative to the combined weight of particles and methanol. B-1 : SR 444 Pentaerythritol Triacrylate available from Sartomer Company. «>

B-2: SR 399 Dipentaerythritol Pentaacrylate available from Sartomer Company.

B-3: SR 502 Alkoxylated Trimethylolpropane Triacrylate available from Sartomer

Company.

B-4: See above description of synthesis. B-5: See above description of synthesis.

B-6: Larostat HTS905 organic antistatic agent, available from BASF.

C-1: Toluene

C-2: Dowanol PM (1-methoxy-2-propanol) available from Dow Chemical.

D-1 : lrgacure 907 available from Ciba Specialty Chemicals. D-2: lrgacure 184 available from Ciba Specialty Chemicals.

Table 2

Notes:

Solid content (%) = weight percentage of solid content relative to total weight of the whole composition (solids + solvent).

Inorganic content (%) = weight percentage of inorganic solids relative to total weight of solids in the composition (inorganic solids + organic solids).

Table 3: Properties of antistatic/ antireflective laminate using the example compositions as high Rl layer.

Preparation of cured film:

The compositions obtained in Examples 1-5 and Comparative Examples 6-7 were applied to a polyester film ("A4300" available from Toyobo Co., Ltd., thickness: 188 Gm) using a wire bar coater #3 or #4 rod for appropriate wet film thickness versus solid contents to obtain same cured film thickness values shown in Table 2. Wet films were then dried in an oven at 8O ⁰ C for three minutes to form films. The films were cured by exposure to a UV-radiation dose of 1.0 J/cm ² using a 300W Fusion D-lamp in an air atmosphere.

Preparation of antistatic/antireflective laminate

The compositions obtained in Examples 1-4 and Comparative Examples 5-6 were applied to a hardcoated polyester film ("A4300" manufactured by Toyobo Co., Ltd., thickness: 188 μm, with a hardcoat layer Desolite® 4D5-15 manufactured by DSM Desotech Inc. applied and cured to a 3 μm cured hardcoat thickness using a #3 wire-wound rod applicator, evaporation step of 3 minutes at room temperature, and exposure to a UV-radiation dose of 1.0 J/cm ² using a 300W Fusion D-lamp in an air atmosphere) using a wire bar coater, and dried in an oven at 8O ⁰ C for one minute to form films. The films were cured by applying ultraviolet rays in air at a dose of 1 J/cm ² using a metal halide lamp to obtain cured films (hardcoat layers) having a thickness shown in Table 1.

A low refractive index coat material ("Desolite® DZ-0009" manufactured by DSM Desotech Inc., solid content: 5% in MEK) was applied to the above cured film by spin coating at 7500 rpm, 3000rpm/s for 12 seconds. The films were then exposed to a UV-radiation dose of 1.0 J/cm ² using a 300W Fusion D-lamp in a Nitrogen atmosphere, forming low refractive index film having a thickness of 0.1 μm to obtain antistatic laminate having antireflection properties.

Evaluation of cured film and laminate (test methods)

Liquid stability:

Liquid compositions (including solvent content) were tested for liquid stability in the following manner: 15g of each coating example were placed in a 2OmL glass scintillation vial with Teflon® cap and the vials were sealed. The sealed vials were placed in a 54 ^° C oven for a period of 72 hours and then removed from the oven and allowed to come to room temperature. The liquid coatings were examined through the glass vial to determine if sedimentation of any coating components had occurred. Sedimentation is an indicator of liquid stability and can indicate nanoparticle flocculation and agglomeration. Coating compositions were also tested for agglomeration by producing 4 micron cured films of the aged compositions and visually examining the cured films for particulates. The presence of particulates having developed after 54 ^° C aging is an indicator of poor liquid composition stability. Particulates can be in the form of agglomerations of inorganic nanoparticles showing an improperly dispersed composition.

Steel wool scratch resistance:

The surfaces of the cured product and antireflection film laminate were rubbed with #0000 steel wool 30 times at a load of 200 g/cm ² to evaluate the scratch resistance of the cured product and antireflection film laminate by naked eye observation according to the following criteria. The results are shown in Table 2 and Table 3.

Grade 5: No scratch was observed. Grade 4: 1-5 scratches were observed. Grade 3: 6-50 scratches were observed. Grade 2: 51-100 scratches were observed. Grade 1 : Peeling of film was observed.

A cured product or laminate with a scratch resistance of grade 3 or more is acceptable in actual application. A cured product or laminate with a scratch resistance of grade 4 or more is preferable since excellent durability is obtained in actual application. A cured product or laminate with a scratch resistance of grade 5 is still more preferable since durability in actual application is significantly improved.

Reflectance percentage:

The reflectance (minimum reflectance in measurement wavelength region) percentage of the laminate was measured at a wavelength of 340nm-700nm using a spectral reflectance measurement system (Perkin Elmer Lambda 9 UV-VIS spectrophotometer or equivalent equipped with specular reflectance accessory) reflectance of the laminate (antireflection film) at each wavelength was measured while using the reflectance of a deposited aluminum film as a standard (100%). The results are shown in Table 3. Reflectance after caustic exposure:

Antistatic/antireflective laminates were tested for change in reflectance after exposure to aqueous caustic solutions to partially quantify chemical resistance. Caustic test solutions were prepared by dissolving NaOH solid pellets (available from Aldrich Co.) into distilled H ₂ O to provide aqueous solutions of 5%w/w aqueous NaOH. Laminate samples were tested for %Reflectance (as described previously). The samples were then placed on a flat surface and 2 mL of the caustic test solution was placed on the samples for a period of 30 minutes. At the end of this

time period, the caustic solution was removed from each sample and the sample was gently rinsed with distilled water and allowed to dry at ambient laboratory conditions. The %Reflectance was then remeasured (as described previously) and the %Reflectance vs. wavelength curve minimum for each sample was again noted. A large change in %Reflectance minimum between exposed and non-exposed samples indicates a low degree of caustic resistance, and vice-versa. The results are shown in Table 3.

Total light transmission % and Haze%: The total light transmission percentage and haze percentage of the cured film and the laminate were measured according to ASTM D1003 standard method using a Haze-gard plus model (available from BYK-Gardner Corp.). The results are shown in Table 2 and Table 3.

Surface resistivity:

The surface resistivity (Ω/square) of the cured film and the laminate was measured according to ASTM D257-99 using a high resistance meter/electrometer (6517A Electrometer manufactured by Keithley Instruments, Inc) and a resistivity cell (model 8009 Resistivity test fixture manufactured by Keithley Instruments, Inc.) The results are shown in Table 2 and Table 3.

Measurement of Film Hardness by Pencil Test (Pencil hardness):

The pencil hardness was measured according to standard method ASTM D3363: The composition was cured on a glass substrate and the coated substrate was placed on a firm horizontal surface. The pencil is held firmly against the film at a 45° angle (point away from the operator) and pushed away from the operator in a 6.5 mm (1/4 in.) stroke. The process started with the hardest pencil and continued down the scale of hardness to either of two end points: one, the pencil that will not cut into or gouge the film (pencil hardness), or two, the pencil that will not scratch the film (scratch hardness)

The pencil hardness of the film is represented by the following letter designations (the film hardness increases from left to right):

6B, 5B, 4B, 3B, 2B, B, HB, F, H, 2H, 3H, 4H, 5H.6H

If the hardness of the film is represented by any letter in the group of (F, H, 2H, 3H, 4H), the film is considered to be sufficiently hard. The results of the film hardness testing are shown in Table 2.

Crosshatch adhesion test:

Cured films and AR laminates were evaluated for Crosshatch adhesion as per ASTM D3359 using a Gardco PAT paint adhesion tester (available from Paul N. Gardner corporation) in ambient laboratory conditions of 25 ^° C and 50% relative humidity. Results are shown in Table 2.

Refractive index of cured film:

A glass microscope slide is coated with a test coating and the coating is cured by UV exposure. (Standard cure conditions: solvent evaporation, cure at 1.0 J/cm ² , Fusion 300 W D-lamp, air atmosphere). 2mm x 2mm squares are cut into the cured film using a razor blade. Alternating squares are removed from the cured film. The slide is then placed under 10x microscope set up for collimated axial transmitted illumination, and fitted with objectives of up to at least 0.70 numerical aperture. Monochromatic illumination is used, which is generally provided by placing narrow bandwidth interference filters in the path of the microscope's built-in illumination system. If provision is made for external illumination sources, a monochromator may also be used to provide a continuously variable source. The normal wavelength used is 589 nm or the Sodium D-line, from whence the designation of refractive index figures as "n". The cured film is then compared to standard liquids of known refractive index (Cargill Index of Refraction Liquids, Standard Group available from McCrone Microscopy Inc.). Using the bottle applicator rod, apply a small drop of the refractive index liquid adjacent to the cover slip fragment so that capillary action carries it beneath the cover slip to fill the spaces around the coating squares. As the microscope focus is adjusted so that the distance between the sample and the objective increases, the Becke ¹ line will move toward the medium of higher refractive index. If the coating has a higher refractive index than the liquid it is mounted in, the Becke' line will move into the outline of the squares as the focus is moved "up". These steps are repeated on fresh coating squares until the outline of the squares disappears or the Becke' line reverses direction from that observed from the previous observation. A higher or lower refractive index liquid is chosen depending on the direction of the refractive index mismatch indicated by the initial observation. If the

outline of the coating squares fails to disappear and two liquids adjacent to one another in the set are found which give opposite signs of Becke' line movement, the refractive index of the material then lies between the two values, most likely centered in the range.

Determination of AR laminate contact angle:

Contact angle of AR laminate samples were performed as per ASTM D5725-99 using distilled H ₂ O as the test liquid. Drops of test liquid were applied to test samples manually using a micropipetter equipped with #8 gauge luer lock needle. Contact angle of applied test drops was determined using a rame-hart standard goniometer with DROPimage standard (p/n 200-00)*(400-30) software, high-resolution CCD camera, fiber optic illuminator, and frame grabber hardware). The results are shown in Table 2.

Viscosity measurement:

The viscosity of the radiation curable composition was measured using the viscometer Paar Physica Z2, with a shear speed of 39rpm at 25°C. The results are shown in Table 2.

95% Relative RAU Dose Test Method

The relative cure rate for the ultraviolet cured coating was determined using an FTIR transmission technique. The instrument used was a Nicolet Nexus 470 FTIR equipped with a DTGS detector. A 100 W mercury lamp was affixed to a shelf in front of the FTIR sample compartment such that the UV light could be focused on a sample placed in the beam path. The lamp was equipped with an electronic shutter capable of controlling exposures of the sample of 0.01 seconds and greater. FTIR sampling parameters were: 4 cm ^"1 resolution and 10 co-added scans for each spectrum. A drop of the desired liquid coating was spin-coated on a KBr crystal until completely covered with the experimental coating at a thickness not exceeding 1.0 micron. The sample was scanned using 100 co-added scans and the spectrum is converted to absorbance. The net peak area of the acrylate absorbance at 810 cm ^"1 of the liquid coating was then measured.

The net peak area was measured using the "baseline" technique in which a baseline is drawn tangent to absorbance minima on either side of the peak. The area under the peak and above the baseline was then determined.

The sample was exposed to a 100W mercury lamp (model 6281 from Oriel Corp.) in an air atmosphere. The FTIR scan of the sample and the measurement of net peak absorbance for the spectrum of the cured coating are repeated. Baseline frequencies are not necessarily the same as those of the liquid coating, but were chosen such that the baseline was still tangent to the absorbance minima on either side of the analytical band. The peak area measurement for a non-acrylate reference peak of both the liquid and cured coating spectrum is repeated. For each subsequent analysis of the same formulation, the same reference peak, with the same baseline points, was utilized. The ratio of the acrylate absorbance to the reference absorbance for the liquid coating was determined using the following equation:

where A _AL = area of acrylate absorbance of liquid A _RL = area of reference absorbance of liquid

R _L = area ratio of liquid

In a similar manner, the ratio of the acrylate absorbance to the reference absorbance for the cured coating was determined using the equation:

R _F = ^-

where A _A F = area of acrylate absorbance of cured coating

A _RF = area of reference absorbance of cured coating R _F = area ratio of cured coating

The degree of cure as percent-reacted acrylate unsaturation (%RAU) was calculated using the following equation:

where R _L = area ratio of liquid

R _F = area ratio of cured coating

Some compositions containing an appreciable level of multifunctional acrylates are known to have relatively low %RAU values, even when fully cured ("% Ultimate RAU"), usually on the order of 55-70% RAU.

"% Relative RAU" represents the degree of curing of a coating composition relative to its % Ultimate RAU, and is defined by the following equation:

% Relative RAU = ((% RAU of test composition)/(% Ultimate RAU))100

The average % Relative RAU was determined for the duplicate analyses for each time exposure for the sample. The time of exposure was then plotted versus %RAU for the sample. Based on the time of exposure and the wattage power of the UV lamp used, the UV exposure experienced by the sample was then calculated in J/cm ² and recorded. The UV dose required to provide 95% of total final %Relative RAU was also calculated and recorded. These values of UV dose to 95% of final %Relative RAU are used to compare the cure speed of one composition to other compositions and comparative examples. Having described specific embodiments of the present invention, it will be understood that many modifications thereof will readily appear or may be suggested to those skilled in the art, and it is intended therefore that this invention is limited only by the spirit and scope of the following claims.