WO2007053158A2

WO2007053158A2 - Low refractive index coating composition for use in antireflection polymer film coatings and manufacturing method

Info

Publication number: WO2007053158A2
Application number: PCT/US2005/044114
Authority: WO
Inventors: Kazuhiko Mizuno
Original assignee: 3M Innovative Properties Company
Priority date: 2004-12-30
Filing date: 2005-12-07
Publication date: 2007-05-10
Also published as: WO2007053158A3; TW200631994A; JP2008527076A

Abstract

A silicone-modified fluoropolymer is formed by first dissolving a fluoropolymer in an organic solvent, the fluoropolymer having at least one monomer of vinylidene fluoride coupled to a hexafluoropropylene monomer unit, and subsequently reacting the mixture with an amino silane coupling agent to form an aminosilane-modified fluoropolymer. The aminosilane fluoropolymer is subsequently heated and partially condensed with an oligomer of a silane compound including alkoxy silane. The resultant composition is suitable for use as a low refractive index layer in an antireflection coating on an optical substrate.

Description

LOW REFRACTIVE INDEX COATING COMPOSITION FOR USE IN ANTIREFLECTION POLYMER FILM COATINGS AND MANUFACTURING

METHOD

Technical Field And Industrial Applicability Of the Invention

The present invention relates to a coating composition and more specifically to a low refractive index composition for an antireflection polymer film.

Background Of The Invention

Antireflective polymer films ("AR films"), or AR coatings, are becoming increasingly important in the display industry. New applications are being developed for low reflective films and other AR coatings applied to articles used in the computer, television, appliance, mobile phone, aerospace and automotive industries.

AR films are typically constructed by alternating high and low refractive index polymer layers in order to minimize the amount of light that is reflected. Desirable features in AR films for use on the substrate of the articles are the combination of a low percentage of reflected light (e.g. 1.5% or lower) and durability to scratches and abrasions. These features are obtained in AR constructions by maximizing the delta RI between the polymer layers while maintaining strong adhesion between the polymer layers.

It is well known that the low refractive index polymer layers used in AR films are usually derived from fluorine containing polymers ("fluoropolymers" or "fluorinated polymers"), which have refractive indices that range from about 1.3 to 1.4.

Fluoropolymers provide unique advantages over conventional hydrocarbon based materials in terms of high chemical inertness (in terms of acid and base resistance), dirt and stain resistance (due to low surface energy), low moisture absorption, and resistance to weather and solar conditions. The refractive index of fluorinated polymer coating layers is dependent upon the volume percentage of fluorine contained within the layers. Increased fluorine content decreases the refractive index of the coating layers. However, increasing the fluorine content also decreases the surface energy of the coating layers, which in turn reduces the interfacial adhesion of the fluoropolymer layer to the other polymer or substrate layers to which the layer is coupled.

Other materials investigated for use in low refractive index layers are silicone- containing polymeric materials. Silicone-containing polymeric materials have generally low refractive indices. Further, silicone-containing polymeric coating layers generally have higher surface energies than fluoropolymer-base layers, thus allowing the silicone- containing polymeric layer to more easily adhere to other layers, such as high refractive index layers, or substrates. This added adhesion improves scratch resistance in multilayer antireflection coatings. However, silicone-containing polymeric materials have a higher refractive index as compared with fluorine containing materials. Further, silicone- containing polymeric materials have a lower viscosity that leads to defects in ultra-thin coatings (less than about 100 nanometers).

Thus, it is highly desirable to form a low refractive index layer for an antireflection film having increased fluorine content, and hence lower refractive index, while improving interfacial adhesion to accompanying layers or substrates.

Summary of the Invention

The present invention provides a composition useful as a low refractive index layer in an antireflection coating and a method for forming the composition.

The present invention combines the unique durability and repellency properties of fluoropolymers with the adhesion advantages of silicone-containing polymeric polymers into a single low refractive index composition.

The present invention provides a silicone-modified fluoropolymer that is formed by first dissolving a fluoropolymer having at least one monomer of vinylidene fluoride coupled to a hexafluoropropylene monomer unit in an organic solvent and subsequently reacting the mixture with an amino silane coupling agent to form an aminosilane-modified fluoropolymer. The aminosilane fluoropolymer is subsequently heated and partially condensed with an oligomer of a silane compound including alkoxy silane. The resultant composition is ideally suited as a low refractive index layer in an AR film because the material shows good wetting to underlying or overlying materials and substrates and farther has adequate viscosity performance. The material is durable and relatively easy to manufacture. This material is also suited as a low refractive index layer in a transferable AR film. One method for application of the transferable material to a (e.g. optical) substrate is by means of a thermal application technique such as an in-mold or heat press technique.

Other objects and advantages of the present invention will become apparent upon considering the following detailed description and appended claims, and upon reference to the accompanying drawings.

Brief Description of the Drawings

Figure 1 is perspective view of an article having an optical display; Figure 2 is a sectional view of the article of Figure 1 taken along line 2-2 illustrating an antireflection film having a low refractive index layer formed in accordance with a preferred embodiment of the present invention; and

Figure 3 illustrates a logic flow diagram for forming a low refractive index composition according to a preferred embodiment of the present invention.

Figures 4-6 is a schematic illustration of a method of forming and applying a transferable antireflection material to an optical substrate according to another preferred embodiment of the present invention.

Detailed Description And Preferred Embodiments Of The Invention

For the following defined terms, these definitions shall be applied, unless a different definition is given in the claims or elsewhere in the specification. The term "polymer" will be understood to include polymers, copolymers (e.g. polymers using two or more different monomers), oligomers and combinations thereof, as well as polymers, oligomers, or copolymers that can be formed in a miscible blend.

The term "low refractive index", for the purposes of the present invention, refers to the property of a composition or material, which forms a coating layer having a refractive index of less than about 1.45 when applied as a layer to a substrate.

The term "high refractive index", for the purposes of the present invention, refers to the property of a composition or material, which forms a coating layer having a refractive index of greater than about 1.6 when applied as a layer to a substrate.

The difference in iiie refractive index between the low index layer and the high index layer is at least about 0.2. However, in general terms, all that is required is that the low refractive index layer is formed having a refractive index less than a high refractive index layer. Thus, coating layers wherein the low refractive index layer having a refractive index slightly greater than about 1.42, when coupled with a high refractive index layer having a refractive index slightly less than about 1.6, wherein the refractive index of the low refractive index layer is less than the refractive index of the high refractive index layer, are also specifically contemplated by the present invention.

The recitation of numerical ranges by endpoints includes all numbers subsumed within the range (e.g. the range 1 to 10 includes 1, 1.5, 3.33, and 10). As used in this specification and the appended claims, the singular forms "a", "an", and "the" include plural referents unless the content clearly dictates otherwise. Thus, for example, reference to a composition containing "a compound" includes a mixture of two or more compounds. As used in this specification and the appended claims, the term "or" is generally employed in its sense including "and/or" unless the content clearly dictates otherwise.

Unless otherwise indicated, all numbers expressing quantities of ingredients, measurements of properties such as contact angle and so forth as used in the specification and claims are to be understood to be modified in all instances by the term "about." Accordingly, unless indicated to the contrary, the numerical parameters set forth in the foregoing specification and attached claims are approximations that can vary depending upon the desired properties sought to be obtained by those skilled in the art utilizing the teachings of the present invention. At the very least, and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claims, each numerical parameter should at least be construed in light of the number of reported significant digits and by applying ordinary rounding techniques. Notwithstanding that the numerical ranges and parameters set forth the broad scope of the invention are approximations, the numerical values set forth in the specific examples reported as accurately as possible. Any numerical value, however, inherently contains certain errors necessarily resulting from the standard deviations found in their respective testing measurements. As used herein, the term "weight ratio" refers to the relative weight of the uυmpunenxs relative to each other based on the coating composition or reaction product thereof unless specified otherwise. Further, the term "percent by weight" or "weight percent" refers to the weight percent solids based on the coating composition or reaction product thereof unless specified otherwise.

In one embodiment, the invention relates to a (e.g. transferable) antireflection material suitable for use on optical substrates. The optical substrate may comprise or consist of any of a wide variety of non-polymeric materials, such as glass, or various thermoplastic and crosslinked polymeric materials, such as polyethylene terephthalate (PET), (e.g. bisphenol A) polycarbonate, cellulose acetate, poly(methyl methacrylate), polyolefϊns such as biaxially oriented polypropylene which are commonly used in various optical devices. The substrate may also comprises or consist of polyamides, polyimides, phenolic resins, polystyrene, styrene-acrylonitrile copolymers, epoxies, and the like.

Typically the substrate will be chosen based in part on the desired optical and mechanical properties for the intended use. Such mechanical properties typically will include flexibility, dimensional stability and impact resistance. The substrate thickness typically also will depend on the intended use. For most applications, substrate thicknesses of less than about 0.5 mm are preferred, and more preferably about 0.02 to about 0.2 mm. Self- supporting polymeric films are preferred. The polymeric material can be formed into a film using conventional filmmaking techniques such as by extrusion and optional uniaxial or biaxial orientation of the extruded film. The substrate can be treated to improve adhesion between the substrate and the hardcoat layer, e.g., chemical treatment, corona treatment such as air or nitrogen corona, plasma, flame, or actinic radiation. If desired, an optional tie layer or primer can be applied to the substrate and/or hardcoat layer to increase the interlayer adhesion.

In the case of display panels, the substrate is light transmissive, meaning light can be transmitted through the substrate such that the display can be viewed. Various light transmissive optical film are known including but not limited to, multilayer optical films, microstructured films such as retroreflective sheeting and brightness enhancing films, (e.g. reflective or absorbing) polarizing films, diffusive films, as well as (e.g. biaxial) retarder films and compensator films such as described in U.S. Patent Application Publication No. 2004/0184150, filed January 29, 2004. As described is U.S. Patent Application 2003/0217806, multilayer optical films, i.e., films that provide desirable transmission and/or reflection properties at least partially by an arrangement of microlayers of differing refractive index. The microlayers have different refractive index characteristics so that some light is reflected at interfaces between adjacent microlayers. The microlayers are sufficiently thin so that light reflected at a plurality of the interfaces undergoes constructive or destructive interference in order to give the film body the desired reflective or transmissive properties. For optical films designed to reflect light at ultraviolet, visible, or near-infrared wavelengths, each microlayer generally has an optical thickness (i.e., a physical thickness multiplied by refractive index) of less than about 1 μm. However, thicker layers can also be included, such as skin layers at the outer surfaces of the film, or protective boundary layers disposed within the film that separate packets of microlayers. Multilayer optical film bodies can also comprise one or more thick adhesive layers to bond two or more sheets of multilayer optical film in a laminate.

The reflective and transmissive properties of multilayer optical film body are a function of the refractive indices of the respective microlayers. Each microlayer can be characterized at least at localized positions in the film by in-plane refractive indices n_x, n_y, and a refractive index n_z associated with a thickness axis of the film. These indices represent the refractive index of the subject material for light polarized along mutually orthogonal x-, y-, and z-axes. In practice, the refractive indices are controlled by judicious materials selection and processing conditions. Films can be made by co-extrusion of typically tens or hundreds of layers of two alternating polymers A₅ B, followed by optionally passing the multilayer extrudate through one or more multiplication die, and then stretching or otherwise orienting the extrudate to form a final film. The resulting film is composed of typically tens or hundreds of individual microlayers whose thicknesses and refractive indices are tailored to provide one or more reflection bands in desired region(s) of the spectrum, such as in the visible or near infrared. In order to achieve high reflectivities with a reasonable number of layers, adjacent microlayers preferably exhibit a difference in refractive index (δ n_x) for light polarized along the x-axis of at least 0.05. If the high reflectivity is desired for two orthogonal polarizations, then the adjacent microlayers also preferably exhibit a difference in refractive index (δ %) for light polarized along the y-axis of at least 0.05. Otherwise, the refractive index difference can be less than 0.05 and preferably about 0 to produce a multilayer stack that reflects normally incident light of one polarization state and transmits normally incident light of an orthogonal polarization state. If desired, the refractive index difference (δ n_z) between adjacent microlayers for light polarized along the z-axis can also be tailored to achieve desirable reflectivity properties for the p-polarization component of obliquely incident light.

Exemplary materials that can be used in the fabrication of polymeric multilayer optical film can be found in PCT Publication WO 99/36248 (Neavin et al.). Desirably, at least one of the materials is a polymer with a stress optical coefficient having a large absolute value. In other words, the polymer preferably develops a large birefringence (at least about 0.05, more preferably at least about 0.1 or even 0.2) when stretched. Depending on the application of the multilayer film, the birefringence can be developed between two orthogonal directions in the plane of the film, between one or more in-plane directions and the direction perpendicular to the film plane, or a combination of these. In special cases where isotropic refractive indices between unstretched polymer layers are widely separated, the preference for large birefringence in at least one of the polymers can be relaxed, although birefringence is still often desirable. Such special cases may arise in the selection of polymers for mirror films and for polarizer films formed using a biaxial process, which draws the film in two orthogonal in-plane directions. Further, the polymer desirably is capable of maintaining birefringence after stretching, so that the desired optical properties are imparted to the finished film. A second polymer can be chosen for other layers of the multilayer film so that in the finished film the refractive index of the second polymer, in at least one direction, differs significantly from the index of refraction of the first polymer in the same direction. For convenience, the films can be fabricated using only two distinct polymer materials, and interleaving those materials during the extrusion process to produce alternating layers A, B, A, B, etc. Interleaving only two distinct polymer materials is not required, however. Instead, each layer of a multilayer optical film can be composed of a unique material or blend not found elsewhere in the film. Preferably, polymers being coextruded have the same or similar melt temperatures. Exemplary two-polymer combinations that provide both adequate refractive index differences and adequate inter-layer adhesion include: (1) for polarizing multilayer optical film made using a process with predominantly uniaxial stretching, PEN/coPEN, PET/coPET, PEN/sPS, PET/sPS, PEN/Eastar,.TM. and PET/Eastar,.TM. where "PEN" refers to polyethylene naphthalate, "coPEN" refers to a copolymer or blend based upon naphthalene dicarboxylic acid, "PET" refers to polyethylene terephthalate, "coPET" refers to a copolymer or blend based upon terephthalic acid, "sPS" refers to syndiotactic polystyrene and its derivatives, and Eastar™ is a polyester or copolyester (believed to comprise cyclohexanedimethylene diol units and terephthalate units) commercially available from Eastman Chemical Co.; (2) for polarizing multilayer optical film made by manipulating the process conditions of a biaxial stretching process, PEN/coPEN, PEN/PET, PEN/PBT, PEN/PETG and PEN/PETcoPBT, where "PBT" refers to polybutylene terephthalate, "PETG" refers to a copolymer of PET employing a second glycol (usually cyclohexanedimethanol), and "PETcoPBT" refers to a copolyester of terephthalic acid or an ester thereof with a mixture of ethylene glycol and 1 ,4-butanediol; (3) for mirror films (including colored mirror films), PEN/PMMA, coPEN/PMMA,

PET/PMMA, PEN/Ecdel™, PET/Ecdel™, PEN/sPS, PET/sPS, PEN/coPET, PEN/PETG, and PEN/THV™, where "PMMA" refers to polymethyl methacrylate, Ecdel™ is a thermoplastic polyester or copolyester (believed to comprise cyclohexanedicarboxylate units, polytetramethylene ether glycol units, and cyclohexanedimethanol units) commercially available from Eastman Chemical Co., and THV™ is a fluoropolymer commercially available from 3M Company.

Further details of suitable multilayer optical films and related constructions can be found in U.S. Pat. No. 5,882,774 (Jonza et al.), and PCT Publications WO 95/17303 (Ouderkirk et al.) and WO 99/39224 (Ouderkirk et al.). Polymeric multilayer optical films and film bodies can comprise additional layers and coatings selected for their optical, mechanical, and/or chemical properties. See U.S. Pat. No. 6,368,699 (Gilbert et al.). The polymeric films and film bodies can also comprise inorganic layers, such as metal or metal oxide coatings or layers.

The surface energy can be characterized by various methods such as contact angle and ink repellency, as determined by the test methods described in the examples. The surface layer and articles described preferably exhibit a static contact angle with water of at least 70 degrees. More preferably, the contact angle is at least 80 degrees and more preferably at least 90 degrees. Alternatively, or in addition thereto, the advancing contact angle with hexadecane is at least 50 degrees and more preferably at least 60 degrees. Low surface energy is indicative of anti-soiling properties as well as rendering the exposed surface cdby iu clean. Another indicator of low surface energy relates to the amount of ink from a pen or marker, which beads up when applied to the exposed surface. The surface layer and articles exhibit "ink repellency" when the ink from pens and markers can be easily removed by wiping the exposed surface with a tissues or paper towels, such as tissues available from the Kimberly Clark Corporation, Roswell, GA under the trade designation "SURPASS FACIAL TISSUE."

The term "optical display" or "display panel" include various illuminated and non- illuminated displays panels. Such displays include multi-character and especially multicharacter, multi-line displays such as liquid crystal displays ("LCDs"), plasma displays, front and rear projection displays, cathode ray tubes ("CRTs"), signage, as well as single- character or binary displays such as light emitting tubes ("LEDs"), signal lamps and switches. The light transmissive (i.e. exposed surface) substrate of such display panels may be referred to as a "lens." The invention is particularly useful for displays having a viewing surface that is susceptible to damage. The coating composition, reactive product thereof, as well as the protective articles of the invention can be employed in a variety of portable and non-portable information display devices including PDAs, cell phones (including combination PDA/cell phones), touch sensitive screens, wrist watches, car navigation systems, global positioning systems, depth finders, calculators, electronic books, CD and DVD players, projection televisions screens, computer monitors, notebook computer displays, instrument gauges, instrument panel covers, signage such as graphic displays and the like. These devices can have planar viewing faces, or non-planar viewing faces such as slightly curved faces.

The coating composition, reactive product thereof, as well as the protective articles of the invention can be employed on a variety of other articles as well such as, for example, camera lenses, eyeglass lenses, binocular lenses, retroreflective sheeting, automobile windows, building windows, train windows, aircraft windows, vehicle headlamp and taillights, and the like. The above listing of potential applications should not be construed to unduly limit the invention.

Referring now to Figure 1, a perspective view of an article, here a computer monitor 10, is illustrated as having an optical display 12 coupled within a housing 14. The optical display 12 is a substantially transparent material having optically enhancing properties through which a user can view text, graphics or other displayed information. As best shown in Figure 2, the optical display 12 includes an antireflection film 18 coupled (coated) to an optical substrate 16. The antireflection film 18 has at least one layer of a high refraction index layer 22 and a low refractive index layer 20 coupled together such that the low refractive index layer 20 is exposed to the atmosphere while the high refractive index layer 22 is contained between the substrate 16 and low refractive index layer 20.

The high refractive index layer 22 is a conventional carbon-based polymeric composition having a mono and multifunctional acrylate crosslinking system. Exemplary non-limiting high refractive index compositions that may be utilized to form the high refractive index layer 22 in the present invention are described in U.S. Patent No.

5,932,626 to Fong et al., assigned to Minnesota Mining and Manufacturing Company of St. Paul, Minnesota; and U.S. Patent No. 6,391,433 to Jiang et al., assigned to Hoya Corporation of Tokyo, Japan.

The low refraction index layer 20 is designed to be compatible with the high refractive index layer 22 and is formed from the reaction product an oligomer of a silicone alkoxy resin partially condensed with an aminosilane modified fluoropolymer. The method for forming the low refractive index layer 20 is described in further detail below.

Articles with which the present invention can be utilized include, for example, lenses, cathode ray tubes, flat or curved panel displays, window films and windshields. It is understood, of course, that the present invention is not limited to such articles, but can be utilized with any articles within the skill of persons in the art.

While not shown, other layers may be added onto the substrate 16, including, but not limited to, other hard coating layers, adhesive layers, and the like. These layers are formed with conventional hydrocarbon-based compositions that are designed to be compatible with the overlying layers of the antireflection material 18.

Further, the antireflection material 18 may be applied directly to the substrate 16, or alternatively applied to a release layer of a transferable antireflection film and subsequently transferred from the release layer to the substrate using a heat press or photoradiation application technique. Figure 3 illustrates a logic flow diagram for forming the low refraction index coating composition used m the low refractive index coating layer 20 of Figure 1 in accordance with one preferred method of the present invention. To form the antireflection coating composition, as shown in Step 100, a fluoropolymer is first dissolved in a compatible organic solvent. Preferably, the solution is about 10% by weight fluoropolymer and 90% by weight organic solvent.

The preferred fluoropolymer is a copolymer that is formed from the constituent monomers known as (poly)tetrafluoroethylene ("TFE" or "PTFE"), hexafluoropropylene ("HFP"), and (poly)vinylidene fluoride ("VdF₅" "V₂F," or "PVdF"). The monomer structures for TFE (1), VdF (2), and HFP (3) are shown below:

CF₂ - CF₂ (1)

CH₂ = CF₂ (2) CF₂ = CF-CF₃ (3)

The fluoropolymer copolymer consists of at least two of the constituent monomers (HFP and VdF), and more preferably all three of the constituent monomers in varying molar amounts. For the purposes of the present invention, a copolymer of all three fluoropolymers shall be hereinafter referred to as THV, while a copolymer consisting of HFP and VdF is hereinafter referred to as FKM (otherwise known as

Hexafluoropropylenevinylidenefluoride). The chemical formulas for FKM (4) and THV (5) are shown below:

One commercially available form of THV contemplated for use in the present invention is Dyneon™ Fluorothermoplastic THV 220, a mixture that is manufactured by 3M of Saint Paul, Minnesota. One commercially available form of FKM is DuPont's Dow Elastomer Viton® A-201C. Useful fluoropolymers are also commercially available, for example from Dyneon LLC, Saint Paul Minn., under the trade names THV 230, THV 500, THV530, Fluorel™ (HFP/VDF), Fluorel-II™ (TFE/PP /VDF), and Kel-F.TM. KF-800, fiuoroelastomer; from Elf Atochem North America Inc., under the trade names Kynar™ 740, 2800, 9301; from Kureha Chemical Co. under the trade name KF polymer; from Daikin Amciiua, Inc. under the trade name NEOFLUORON VDF; from Central Glass under the trade name Cefral Soft™ G-150, from Asahi Glass Co., Ltd., under the trade name AFLAS™ 200; and from DuPont under the tradename Dow Elastomer Viton® A- 201C.

The compatible organic solvent that is utilized in the preferred embodiments of the present invention is methyl ethyl ketone ("MEK"). However, other organic solvents may also be utilized, as well as mixtures of compatible organic solvents, and still fall within the spirit of the present invention. For example, other organic solvents contemplated include methyl isobutyl ketone ("MIBK"), methyl amyl ketone ("MAK"), tetrahydrofuran ("THF"), isopropyl alcohol ("IPA"), and mixtures thereof.

The mechanical durability of the resultant low retractive index layer 20 can be enhanced by the introduction of surface modified inorganic particles to the low refractive index composition.

The inorganic particles preferably have a substantially monodisperse size distribution or a polymodal distribution obtained by blending two or more substantially monodisperse distributions. The inorganic oxide particles are typically non-aggregated (substantially discrete), as aggregation can result in precipitation of the inorganic oxide particles or gelation of the hardcoat. The inorganic oxide particles are typically colloidal in size, having an average particle diameter of 5 nanometers to 100 nanometers. These size ranges facilitate dispersion of the inorganic oxide particles into the binder resin and provide ceramers with desirable surface properties and optical clarity. The average particle size of the inorganic oxide particles can be measured using transmission electron microscopy to count the number of inorganic oxide particles of a given diameter. Inorganic oxide particles include colloidal silica, colloidal titania, colloidal alumina, colloidal zirconia, colloidal vanadia, colloidal chromia, colloidal iron oxide, colloidal antimony oxide, colloidal tin oxide, and mixtures thereof. Most preferably, the particles are formed of silicone dioxide (SiO₂).

The surface particles are modified with polymer coatings designed to have reactive functionality towards the fluoropolymer component of the fluoropolymer phase. Such functionalities include mercapotan, vinyl, acrylate and others believed to enhance the interaction between the inorganic particles and low index fluoropolymers, especially those containing bromo or iodo cure site monomers. The surface modifications allow further Ciussiiπking of 'the particle within the polymer network and allow adequate dispersion of the particles in the fluoropolymer matrix. Next, in Step 110, a solution of amino silane coupling agent, is added to the fluoropolymer solution. One preferred amino silane coupling agent is 3-aminopropyl methoxy silane:

H₂N-(CH₂)₃-Si(OMe)₃ (6) The mixture is allowed to sit for a sufficient period of time to fully react the mixture to form an amino-silane modified fluoropolymer. In the preferred embodiment of the present invention, the mixture was allowed to react for about 10 days at room temperature.

The reaction mechanism for forming the aminosilane modified fluoropolymer preferentially and substantially occurs at vinylidene fluoride groups that are located next to HFP groups in the THV or FKM molecules. The reaction mechanism is a dehydrofluorination reaction of the VdF group followed by Michael addition reaction and is described chemically below (for illustrative purposes, 3-aminopropyl methoxy silane is utilized as the amino silane coupling agent):

~ CF₂ CF CH₂ CF₂ ~

^CF3 + H₂N-(CHa)₃-Si(OMe)₃ →

~

The reaction is limited by the number of VdF groups coupled to the HFP groups contained in the fluoropolymer. As a result, excess amino silane coupling agent in solution has little, if any, additional chemical effect. The amino silane coupling agent is added in a range of between about 5 and 10 weight percent of the total mixture.

In Step 120, the aminosilane modified fluoropolymer solution is placed into a container and reacted with an oligomer of a silane compound having the chemical formula:

Si-(ORl)_raR2_n (8) wherein ϊ? 1 o^r^ g_2 are alkyl groups, m in a whole number between 1 and 4, n is a whole number between 0 and 3, and wherein the sum of m and n is 4. Two preferred oligomers that meet these criteria are organic alkoxy silanes and tetraalkoxy silanes. In alternative preferred silane compounding oligomer, a portion of the Rl alkyl may be replaced by an acetyl group.

Preferably, the oligomer of a silane compound is a mixture of organic alkoxy silane and tetraalkoxy silane, with the preferred weight ratio of tetraalkoxy silane to organic alkoxy silane in the resultant composition being between about 2: 1 and 3:1. The solids of the mixture are ideally adjusted to between about 2 and 10 weight percent, using a compatible organic solvent that quenches the reaction, and more desirably between about 8 and 10 weight percent. One preferred solvent to quench the reaction and prevent gelation is THF. However, because THF has a low boiling point, a higher boiling point solvent, such as propylene glycol monomethyl ether acetate ("PMA"), is preferably added as a portion of the solvent package.

The container containing the mixture is placed in a heated water bath for between about 1 and 4 hours at between 60 and 80 degrees Celsius in order that the pendent silicone methoxy groups of the amino-silane modified fluoropolymer solution react, via a condensation reaction, with the alkoxy silane portion of the organic alkoxy silane or tetra alkoxy silane. The reaction mechanism for first forming the resultant product, a silicone modified fluoropolymer, mixed with tetramethoxy silane (the tetraalkoxy silane oligomer) and alkyl-trimethoxy silane (the organic alkoxy silane oligomer) is shown below:

(9) wherein FP indicates the rest of the fluoropolymer backbone.

Excess tetraalkoxy silane oligomer and organic silane oligomer remaining in the mixture will further react to form three-dimensional crosslinked networks via the following reaction mechanism:

OCH, OCH,

R"¹ ""' ""Si - — ⁱ — -Q— — — Sl ^■" " " 'O~~""~"Si(OCri3)3

OCH₃ OCH₃

(IUj In Step 130, the resultant product, a silicone modified fluoropolymer, is removed from the water bath and thinned to less than about 10 weight percent solids, and more preferably around 2 weight percent, with an organic solvent. The addition of the solvent, in essence, quenches the reaction, therein preventing further reaction to prevent gelation of the product. THF is the preferred solvent for quenching the resultant product, but exhibits too fast a drying rate to be used in a thin coating. Therefore, it is preferable to utilize a mixture of THF with another compatible high boiling point solvent such as cyclohexanone and MIBK, the mixture amounts depending upon the desired drying rate for the applied coating. In addition, to increase solution stability, a stabilizing agent such as dibutyltin dilaurate is also added to the final mixture. This stabilizing agent complexes with some of the remaining alkoxy silane in the resultant product. The stabilizing agent is typically added at between about 1 and 3 weight percent of the thinned solution.

The resultant composition is ideally suited as a low refractive index layer because the material shows good wetting to underlying or overlying materials and substrates and further has adequate viscosity performance. The material is easy to manufacture because of its relatively simple synthesis procedure.

Transferable antireflection material can be applied, after formation, to the substrate by various techniques. In one technique, the transferable antireflection material is applied with a radiation curing technique as described in U.S. Application No. 11/027655, filed Dec. 30, 2004. An alternative technique is a thermal application technique such as a heat transfer method or in-mold transfer process, as described below in Figures 4-6.

Figures 4 and 5 below illustrate two methods for forming an optical display via a thermal application technique. The process for either technique begins by first providing the transferable antireflection film 30. The deviation in either process involves the subsequent application of the transferable film to the optical substrate 42.

To form the transferable antireflection film 30, the antireflection coating layers 34 are first applied, one layer at a time, to a temporary transferring material known as a release layer 32. The release layer 32 is preferably a material that is capable of adhering any layer of coaling applied xo it for storage and transport. The release layer 32 also has a stable transfer performance of the antireflection material 34 to the substrate 42 during the subsequent application stage. One preferred release layer meeting these requirements is polyethylene terephthalate film, or PET film, having a thickness of about 25-75 microns.

Next, a wet layer of low refractive index 36 is applied to the release layer 32 using a Mayer bar or similar device. This wet layer 36 is then dried in an oven to a preferred dry thickness of about 75- 100 nanometers.

The low index reflection layer 36 is preferably the previously described silicone- modified fluoropolymer material having good durability and low refractivity. The layer 16 also has appropriate adhesion to the release layer 32 and adequate adhesion to the later- applied high index refraction layer 38. Next, a wet layer of a high index refraction material is applied to the dried low refraction index layer 36 using a Mayer bar or similar device. The high index material is dried in an oven and irradiated with an ultraviolet light source from the PET film 32 side to form a high index layer 38 having a thickness of about 100-125 nanometers.

The main component of the high index matrix resin is a monomer or an oligomer having one or more ultraviolet light ("UV") curable double bonds in order that the resultant layer 38 formed has sufficient cohesion force (by high cross-linking density). Due to reaction speed, acrylic monomers or oligomers are desirable for use as the high index matrix resin.

To increase the cross-linking density within the layer 38, multi-functional monomers or oligomers are also utilized as a portion of the matrix resin. Two preferred multi-functional acrylates that are utilized are Dipentaerithriotal penta/hexaacrylate (DPHA) and pentaerithritol tri/tetra acrylate (PETA).

In addition, it is also desirable to use a multi-functional epoxy acrylate as a portion of the matrix resin to improve scratch resistance performance. Two preferred multifunctional epoxy acrylates that may be used are Bisphenol A epoxy acrylate and Cresol novolac epoxy acrylate.

Zirconium dioxide ("ZrO₂") and titanium dioxide ("TiO₂") are desirable particles for use in high index refractive layers 38. The particle size of the high index inorganic particles is preferably less than about 50 nm in order that it is sufficiently transparent. When electric conductivity is necessary, indium tin oxide ("ITO") and antimony tin oxide ("ATO") are desirably used. These high index particles are first mixed with an organic solvent by using common organosol preparation methods. One example is to prepare a sol in water and then replace the water slowly with organic solvent. Another example is to first disperse the dried particles in organic solvents. In one embodiment, dried rutile fine TiO₂ particles are dispersed with dispersant in an organic solvent using a sand mill. The particles are then introduced to the matrix resin to form the high index composition for the layer 38.

In order to increase adhesion of the high refractive index layer 38 to the low refractive index layer 16, it is desirable that the composition of the high refractive layer 38 includes alkoxy silyl groups. To accomplish this, it is desirable to include a silane coupling agent in the component of the high index layer. Since the high index layer is preferably an acrylates bond material, silane coupling agent with acrylic functional group is preferably utilized.

The reaction mechanism for forming the ammosilane modified fluoropolymer preferentially and substantially occurs at vinylidene fluoride groups that are located next to HFP groups in the THV or FKM molecules. The reaction mechanism is a dehydrofluorination reaction of the VdF group followed by an Michael addition reaction.

Because the low refractive index layer 36 mentioned above also includes alkoxy silyl groups, siloxane bonding will occur at the layer interface when the high index layer 38 is cured. These siloxane bonds are believed to improve scratch resistance of the transferable material 30 after application to the substrate 42.

During the UV curing process of the high index layer 38, UV irradiation of more than 300 nm should be utilized to prevent the low index layer 36 from increasing adhesion to the PET release layer 32 to undesirable levels, therein adversely affecting the subsequent release performance of the release layer 32. For this reason as well, UV exposure of the high index layer 38 is preferably done from the PET side 32 to filter off the short UV light ranges. Since this high index layer 38 is very thin, typically around 100 nm, it is also desirable to irradiate the layer under an inert gas atmosphere to substantially prevent oxygen free radical damage that may occur.

As the solvent of the high index layer 38 solution, alcohol solvents are desirable considering the surface tension and solubility of the low index layer 36. Isopropyl alcohol ("irA") Ib ώoughi io be the best. To help the solubility of the high matrix resin 38 and to control the drying speed of the high index layer 38, other organic solvents such as methyl ethyl ketone ("MEK") and butyl cellosolve can also be used.

Next, a wet layer of a hard coating material, such as layer 40, is applied to the high refractive index layer 38 using a Mayer bar or similar device. The hard coating film is dried in an oven and exposed to an ultraviolet light source, from the PET film 12 side. This forms a hard coating layer having a thickness of about 5 microns. A corona discharge treatment is next optionally and preferably applied to the exposed surface of the hard coat layer 40.

The purpose of the hard coating layer 40 is to prevent scratching. The scratch resistance of the layer is dependent upon the crosslinking density of the hard coating layer

40. Further, the adhesion of the hard coat layer 40 to the high refractive index layer 38 is partially dependent upon the compatibility of the hard coating layer 40 to the high index refraction layer 38.

As such, a desirable hard coating composition for use in the present invention is an acrylic UV curable system that increases the interfacial adhesion to the overlying acrylic high refractive index layer 38. Further, the use of a multifunctional acrylic monomer and a multifunctional polyurethane acrylate is desirable. For improved flexibility, difunctional acrylate resins are preferred over trifunctional or higher order acrylate resins.

Next, an adhesive material 41, such as layer 41, is applied to the hard coating layer 40 using a Mayer bar or similar device and dried in an oven to form an adhesive layer. The corona discharge treatment previously applied to the hard coating layer 40 acts to increase the interfacial adhesion between the hard coating layer 40 and the adhesive layer

41. Preferably, the adhesive layer 41 has a thickness of about 2 micrometers. The adhesive layer 41 is chosen based on its affinity with the substrate material 22 and hard coating layer 40 to which it is applied. Copolymers of polyvinyl chloride/poly vinyl acetate and acrylic polymers are preferably used for this purpose.

Thus, the transferable antireflection layer 30 of Figures 2 and 3 is fully formed and is stored until needed.

One method of thermally coupling the transferable antireflection material comprises providing a mold having a bottom plate and a top plate; introducing the optical substrate and said transferable antireflection material such that said adhesive layer is closely coupled to the optical substrate; heating the top and bottom plate; closing the mold thereby adhering the adhesive layer to the optical substrate; opening the mold; and removing the optical device from the mold.

As described further in Figure 2, the transferable antireflection layer 30 and optical substrate 42 are placed into a heat mold 46, with the adhesive layer 41 being closely coupled to the substrate 42. The mold 46 is then closed. A heated upper plate 48 is pressed at a first pressure onto the release layer 42, while a heated lower plate 50 is pressed in the opposite direction onto the substrate 42 for a predetermined amount of time sufficient to adhere the adhesive layer 41 to the substrate 42. The mold 46 is then opened, and the optical substrate having the coupled transferable layer 30 is removed and cooled. Next, the release layer 32 is peeled away from the low refraction index layer 36. The result is a transferable antireflection film 30 being applied to the optical substrate 42.

Alternatively, as described in Figure 3, the transferable antireflection film 30 can be applied to an optical substrate 42 as the optical substrate is being formed via an in-mold transfer process as described below in Figures 3-5. Such method may comprise introducing the transferable antireflection material within an inner cavity of a molding die; closing the molding die; injecting a quantity of a molten polymeric material to substantially fill the inner cavity, cooling the molten polymeric material; removing the optical substrate having the applied transferable antireflection material from the molding die; and removing the release layer from the low refractive index layer.

Referring to Figure 3, the transferable antireflection film 30 is first placed within an injection mold 73 between a first piece 75 and a second piece 77. The release layer 32 is closely coupled to the second piece 77 and away from the first piece 75.

The mold 73 is closed, as shown in Figure 4, and the transferable film 30 is contained within a cavity 71 defined by the inner surfaces 79, 81 of the first piece 75 and second piece 77, respectively. A quantity of molten optical substrate polymeric material 83 is introduced (i.e. injected) through an opening 85 within the first piece 75 at a predetermined temperature and pressure. The molten material 83 fills the cavity 71 and causes the transferable film 10 to be pressed against the inner surface 81 of the second piece 77. The molten material 79 is then cooled to form the optical substrate 42. The interaction between the adhesive layer 41 and cooled substrate 42 creates adhesion to couple the transferable antireflection film 30 to the formed substrate. Finally, as shown in Figure 5, the mold 73 is opened, and the optical substrate and transferable film 30 are removed from the cavity 71. The release layer 32 is then peeled away from the low refraction index layer 36, leaving the formed optical display.

The present transferable antireflection material offers several advantages. First, the material does not have strong adhesion to the PET film, so stable transfer is achieved without an additional release layer. Second, the high index refraction layer is stably constructed on the low index layer without causing a dewetting problem. Third, because the low index refraction layer includes numerous functional groups to form siloxane bonds, the resultant material achieves high durability. Fourth, the low index refraction layer is porous enough to allow the high index refraction layer to partially penetrate upon application, therein improving adhesion between the layers, which results in improved scratch resistant in the overall coating layer.

EXAMPLES:

By the method shown below, three compositions, including a silicone material modified fluoropolymer, were prepared.

Example 1. Preparation of Fluoro-plastic/Silicone alkoxy oligomer system ("L-I") (a) Modification of Fluoroplastic

4g of THV 220 (Dyneon) were dissolved in MEK and 4Og of a 10 weight percent solution was prepared. In the solution, 255g of ethyl acetate and 0.74g of a 60% by weight solution of oligomerized amino silane coupling agent (LJ-292130, Sumitomo 3M) were added and mixed. The solution was allowed to sit in an airtight container for 10 days under ambient conditions. After 10 days, the solution, known as a modified polymer solution, was slightly yellow. The solids percentage was about 1.5 weight percent and the weight ratio of THV 220 to oligomerized amino silane coupling agent was 90/10.

(b) Condensation with silicone alkoxy oligomer

1Og of the modified polymer solution, 0.65g of an organic alkoxy silane oligomer

(SI oligomer 2, GE Toshiba silicone), 0.33g of an oligo tetra methoxy silane (X40-2308, Shinetsu chemical), 4.9g of methyl amyl ketone and 9.1 Ig of Ethyl acetate were mixed in a container. The mixture was applied to a PET substrate material with a Mayer bar, and the resultant coating layer showed a very hazy appearance. This same mixture was then introduced to a 8O⁰C water bath for 4 hours. The heated mixture was applied to a PET substrate material with a Mayer bar. Here, the resultant coating layer showed a transparent appearance without haze, which indicates that a reaction has taken place. Measurement of the solids percentage of the heated mixture was 2 weight percent and the weight ratio of Fluoropolymer/Organic silicone oligomer/Oligo methoxy silane in the heated mixture was 23.7/23.7/52.6.

Example 2. Preparation of Fluoro-plastic/Silicone alkoxy oligomer system ("L-2")

(a) Modification of Fluoroplastic 4g of THV 220 (Dyneon) were dissolved in MEK and 40 grams of a 10 weight percent solution was prepared. In the solution, 240.5g of THF and 0.2 Ig of an amino silane coupling agent (KBM-903, Shinetsu chemical) were added and mixed. The solution was then allowed to sit in an airtight container for 10 days under ambient conditions. After 10 days, the solution was slightly yellow. The measured solids percentage of the mixture was about 1.5 weight percent and the weight ratio of THV 220/KBM-903 was measured at 95/5.

(b) Condensation with silicone alkoxy oligomer

1Og of the modified polymer solution, 0.9g of an organic alkoxy silane oligomer (SI oligomer 2, GE Toshiba silicone), 0.63g of an oligo tetra methoxy silane (X40-2308, Shinetsu chemical), and 7.23g of THF were mixed in a container. The mixture was then coated onto a PET substrate material using a Mayer bar, and the resultant coating showed a very hazy appearance.

This same mixture was then introduced to a 80°C water bath for 2 hours. The heated mixture was applied to a PET substrate material with a Mayer bar. Here, the resultant coating showed a transparent appearance without haze. Measurement of the solids percentage of the heated mixture was 4 weight percent and the weight ratio of F- polymer/Organic silicone oligomer/oligo methoxy silane in the mixture was determined to be 15/22.5/62.5. Just after reaction completion, 8g of the reaction product above were thinner! hγ

11.23 of THF and 2.1 g of Cyclohaxanone. Example 3. Preparation of Fluoro-elastomer/Silicone alkoxy oligomer system ("L-

3")

(a) Modification of Fluoroelastomer

4Og of FT-2430 (Dyneon) were dissolved in MEK and 400 grams of a 10 weight percent solution was prepared. In the solution, 1001.4g of THF and 2.11 g of an amino silane coupling agent (KBM-903, Shinetsu chemical) were added and mixed. This solution was allowed to sit in an airtight container for 10 days under ambient conditions. After 10 days, the solution was slightly yellow. The solids percentage was measured at about 3.0 weight percent and the weight ratio of FT-2430/KBM-903 was determined to be 95/5. (b) Condensation with silicone alkoxy oligomer

400g of the modified polymer solution, 72g of an organic alkoxy silane oligomer (SI oligomer 2, GE Toshiba silicone), 5Og of an oligo tetra methoxy silane (X40-2308, Shinetsu chemical), 24g of THF and 54g of PMA were mixed in a container. The mixture was then coated onto a PET substrate material using a Mayer bar, and the resultant coating showed a very hazy appearance.

This same mixture was then introduced to a 80°C water bath for 1.5 hours. The heated mixture was applied to a PET substrate material with a Mayer bar. Here, the resultant coating showed a transparent appearance without haze. Measurement of the solids percentage was 10 weight percent and the weight ratio of F-polymer/Organic silicone oligomer/Oligo methoxy silane was determined to be 15/22.5/62.5.

Just after reaction completion, 29Og of the reaction product above was thinned by 448.2g of THF, 502.5g of MEK, 335g of MIBK and 172.7g of Cyclohaxanone. Moreover, 8.7g of a 10% solution of D-butyl tin dilaurate in MEK was added to the resultant mixture. Comparison of Results

L-I, L-2, and L-3 were coated on 75 um PET film substrate material with Mayer bar and dried to a target thickness of about 110 nm. For comparative purposes, four samples of commercially available materials were also prepared and applied to a 75 um PET film substrate niώieiiαϊ ai a similar thickness (between 95 and 110 nm) and evaluated versus L-I, L-2 and L-3. These commercially available materials were a 1.5% solution of THV 220 in ethyl acetate ("C-I"), TMOl 1 (JSR) contained in MIBK ("C-2"), a commercially available solution of an oligo organo silane material, SI oligomer 2 (GE Toshiba silicone), thinned in IPA ("C-3"), and a commercially available oligo organo silane material, KR-400 (Shinetsu chemical), thinned in IPA ("C-4")

The samples were then compared for spectral reflectance and surface quality (in terms of a uniform or non-uniform smooth surface). To measure spectral reflectance, a black acrylic board was attached to a coating sheet on the opposite side of the low refractive index side. The spectral reflectance at 550 nm was measured by a spectrometer, F-20 (Filmetrics). Table I

As shown in Table I, samples embodying the principals of the present invention (L-I, L-2, and L-3) showed improved spectral reflectance properties as compared with all of the control samples. Further, the surface appearance of L-I, L-2 and L-3 was also as good as, and in many cases better, than the surface quality of the control samples.

Examples Transferrable Antireflective Materials Applied With Thermal Application Techniques

1. Preparation of solution for low index layer

Preparation of Lt-I (Modification of Fluoro-elastomer):

4Og of FT-2430 (Dyneon) is first dissolved in MEK and 400g of a 10 weight percent solution was prepared. In the solution, 1001.4g of THF and 2.1 Ig of amino silane coupling agsnt (KBM-903, Slύπcisu Chemical) were added and mixed. The resultant solution was allowed to sit in an airtight container for 10 days under ambient conditions. After 10 days, the resultant solution was a little yellow. The solids percentage was 3.0 weight percent and the weight ratio of FT-2430/KBM-903 was about 95/5.

Preparation of Lt-I (Condensation with silicone alkoxy oligomer):

40Og of the modified polymer solution, 72 of organic alkoxy silane oligomer (SI oligomer 2, GE Toshiba Silicone), 5Og of oligo tetra methoxy silane (X40-2308, Shinetsu Chemical), 24g of THF and 54g of PMA were mixed. When coated by Mayer bar, the resultant coating appeared hazy.

This mixture was then kept in 8O⁰C water bath for 1.5 hours. When coated by Mayer bar, the resultant coating showed a transparent appearance without haze. Solids percentage was 10 weight percent and F-polymer/Organic silicone oligomer/Oligo methoxy silane ratio was maintained at 15/22.5/62.5.

Just after reaction completion, 29Og of the reaction product described above is thinned with 448.2g of THF, 502.5g of MEK, 335g of MIBK and 172.7g of Cyclohexanone. Moreover, 8.7g of a 10% solution of Dibutyltin dilaurate in MEK was added to the resultant mixture, named L- 1.

Preparation of Lt-2:

A copolymer of Tetrafluoroethylene (TFE), Hexafluoropropylene (HFP), and Vinylidenefluoride (VdF) (Product name: THV220, Dyneon) was dissolved in Methyl Ethyl Ketone (MEK) to form a 10 weight percent solution. 3g of the 10% THV solution was further diluted with 1.5g of Ethyl Acetate and 0.5g of N-methyl Pyrrolidinone. This solution was named as L-2, and the solids percentage was maintained at 1.5 weight percent.

Preparation of Lt-3:

Solution Lt-3 was a commercially available solution of UV curable fluorinated acrylic compound (Product name: TMOl 1, JSR) diluted with Methyl Isobutyl Ketone (MIBK) to 1.5 weight percent solids.

Preparation of Lt-4:

Solution Lt-4 was a commercially available oligo organo silane material (Product name: SI oligomer 2, GE Toshiba Silicone) diluted with to 2.0 weight percent solids in IPA.

2. Preparation of solution for low index layer

Preparation of TiO2 dispersion: 50Og Of TiO₂ particles with Rutile structure (Product name: TTO-V-3, Ishihara), 25Og of dispersant (Product name: Disperbyk 2000, BYK Chernie), 104Og of IPA, and 21Og of Butyl Cellosolve were mixed well to obtain a TiO₂ dispersion. The solids percentage of the dispersion was adjusted to 22.1 weight percent. Preparation of oligomer of silane coupling agent (5103 Hv) :

In a covered glass bottle, 5g of acryloxypropyl methoxy silane (Product name: KBM5103, Shinetsu Chemical), 3.62g of deionized water, 0.22g of 0.1N aqueous hydrochloric acid and 6g of IPA were mixed together. This mixture was kept in 80°C oven for 12 hours. The final solids percentage was adjusted to 23.5 weight percent. Preparation of solution for high index layer (H- 1 ):

Ig of the TiO₂ dispersion described above was mixed in a glass bottle with 13.92g of IPA, 1.4g of MEK, 0.87g of Butyl Cellosolve, and the mixture was treated with ultrasonic agitation for 5 minutes. To this mixture was added 1.22g of Novolac epoxy acrylate (Product name: NK oligo EA-7420, ShinNakamura Chemical), 1.22g of Pentaerythritol tri/tetra acrylate (Product name: NK ester A-TMM-3, ShinNakamura Chemical), 0.26g of 5103Hy described above, 0.18g of a 5 weight percent solution of photo-initiator (Product name: Irgacure 369, Ciba Specialty Chemical) in MEK and 0.18g of a 5 weight percent solution of Dibutyltin dilaurate in MEK. The resultant mixture was stirred and the solids percentage was adjusted to about 2.6 weight percent. Preparation of solution for high index layer (H-2):

Ig of the TiO₂ dispersion described above was mixed in a glass bottle with 14.12g of IPA, 0.85g of MEK, 0.87g of Butyl Cellosolve, and the mixture was treated with ultrasonic agitation for 5 minutes. To this mixture was added 1.53g of Novolac epoxy acrylate (Product name: NK oligo EA-7420, ShinNakamura chemical), 1.53g of Pentaerythritol tri/tetra acrylate (Product name: NK ester A-TMM-3, ShinNakamura chemical), 0.18g of a 5 weight percent solution of photo-initiator (Product name: Irgacure 369, Ciba specialty chemical) in MEK and 0.18g of a 5 weight percent solution of Dibutyltin dilaurate in MEK. The resultant mixture was stirred and the solids percentage was adjusted to 2.6 weight percent. Preparation of solution for high index layer (H-3):

Ig υf ihe TiO2 dispersion described above was mixed in a glass bottle with 13.92g of IPA, 1.4g of MEK, 0.87g of Butyl Cellosolve, and the mixture was treated with ultrasonic agitation for 5 minutes. To this mixture was added 2.44g of Pentaerythritol tri/tetra acrylate (Product name: NK ester A-TMM-3, ShinNakamura chemical), 0.26g of 5103Hy described above, 0.18g of a 5 weight percent solution of photo-initiator (Product name: Irgacure 369, Ciba specialty chemical) in MEK and 0.18g of a 5 weight percent solution of Di-butyltin dilaurate in MEK. The resultant mixture was stirred and the solids adjusted to 2.6 weight percent.

Preparation of solution for high index layer (H-4):

Ig of a TiO₂ dispersion described above was mixed in a glass bottle with 13.92g of IPA, 1.4g of MEK, 0.87g of Butyl Cellosolve, and the mixture was treated with ultrasonic agitation for 5 minutes. To this mixture was added 2.44g of Novolac epoxy acrylate (Product name: NK oligo EA-7420, ShinNakamura Chemical), 0.26g of 5103Hy described above, 0.18g of a 5 weight percent solution of photo-initiator (Product name: Irgacure 369, Ciba Specialty Chemical) in MEK and 0.18g of a 5 weight percent solution of Di-butyltin dilaurate in MEK. The resultant mixture was stirred and the solids percentage was adjusted to 2.6 weight percent.

3. Preparation of solution for hard-coating (HC- 1 )

In a glass bottle, 3g of a 50 weight percent solution of polyurethane acrylate (Product name: U-15HA, ShinNakamura chemical) in Toluene, 1.5g of Pentaerythritol tri/tetra acrylate (Product name: NK ester A-TMM-3, ShinNakamura chemical), 1.29g of 1.6-Hexanediol diacrylate (Product name: NK ester A-HD-N, ShinNakamura chemical), 2.14g of 10 weight percent solution of photo-initiator (Product name: Irgacure 184, Ciba specialty chemical) in Toluene and 3.32g of Toluene were mixed and stirred. The solids percentage was adjusted to 40 weight percent.

4. Preparation of solution for adhesive layer (Adh-1) In a glass bottle, 1 Og of a 20 weight percent solution of acrylic polymer (Product name: Paraloid B-44, Rohm & Haas) in MEK, 2.2g of MEK and 1.13g of Cyclohexanone were mixed and stirred well. The solids percentage was adjusted to 15 weight percent.

Example 1: On 75 um PET (Product name: 0-75, Teijin), L-I described above was coated by Mayer bar #6 and dried in 80⁰C oven for 30 seconds and then put in 12O⁰C oven for 20 seconds to make a low index layer with approximately 90 run thickness. On the low index layer, H-I was coated by Mayer bar #8 and dried in 80⁰C oven for 30 seconds and then put in 120⁰C oven for 20 seconds. The H-I coated film was UV exposed for 8 seconds from the PET release layer side with a 120 W Fusion lump (D bulb) under nitrogen gas atmosphere to make a high index layer with approximately 130 run thickness. On the high index layer, HC-I was coated by Mayer bar #10 and dried in 80°C oven for 60 seconds. This coated film was UV exposed for 8 seconds from the PET release layer side with a 120 W Fusion lump (D bulb) under N2 atmosphere to make hard coating layer with approximately 5 um thickness. Moreover, on the hard coating layer, Adh-1 was coated by Mayer bar #9 and dried in 8O⁰C oven for 60 seconds to make adhesive layer with approximately 2 um thickness and then transferable AR material named TAR-I was completed. In the next step, TAR-I and a commercial acrylic board with 7 cm square and 2 mm thickness were put together and inserted into a heat-press machine with two metal plates and heat-pressed for 40 seconds with 30 MPa pressure. The temperatures of the plates were 180⁰C for film/acrylic side and 50°C for the opposite side. The pressed materials were taken out and PET film was removed after cooling. As a result, the anti- reflection layer was successfully transferred on the acrylic surface.

Example 2: TAR-I in Example 1 was inserted into a molding die and PMMA was injection molded with 24O⁰C injection temperature. The pressed materials were taken out and PET film was removed after cooling. As a result, the anti-reflection layer was successfully transferred on the molding surface. Example 3: The same procedure was taken to make TAR-2 except using H-3 in

Example 1.

In the next step, TAR-2 and a commercial acrylic board with 7 cm square and 2 mm thickness were put together and inserted into a heat-press machine with two metal plates and heat-pressed for 40 seconds with 30 MPa pressure. The temperatures of the plates were 180⁰C for film/acrylic side and 50°C for the opposite side. The pressed materials were taken out and PET film was removed after cooling. As a result, the anti- reflection layer was successfully transferred on the acrylic surface.

Example 4: The same procedure was taken to make TAR-3 except using H-4 for H-I in Example 1. In the next step, TAR-3 and a commercial acrylic board with 7 cm square and 2 mm ihickness were put together and inserted into a heat-press machine with two metal plates and heat-pressed for 40 seconds with 30 MPa pressure. The temperatures of the plates were 180⁰C for film/acrylic side and 50°C for the opposite side. The pressed materials were taken out and PET film was removed after cooling. As a result, the anti- reflection layer was successfully transferred on the acrylic surface.

Comparison Example T-I: The same procedure was employed as Example 1 except using Lt-2 in place of Lt- 1.

In the next step, this transferable AR material and commercial acrylic sheet with 7 cm square and 2 mm thickness were put together and were inserted into a heat-press machine with two metal plate and heat-pressed for 40 seconds with 30 MPa pressure. The temperatures of the plates were 180°C for film/acrylic side and 50°C for the opposite side. The pressed materials were taken out and PET film was removed after cooling. As a result, the breaking portion was the interface of low index layer and high index layer and antireflection material transfer failed. The reason for the failure was attributed to too much adhesion of the low index layer to the PET release layer.

Comparison Example T-2: The same procedure was employed as Example 1 except using Lt-4 in place of Lt- 1.

In the next step, this transferable AR material and commercial acrylic sheet with 7 cm square and 2 mm thickness were put together and were inserted into a heat-press machine with two metal plates and heat-pressed for 40 seconds with 30 MPa pressure. The temperatures of the plates were 180⁰C for film/acrylic side and 50⁰C for the opposite side. The pressed materials were taken out and PET film was removed after cooling. As a result, the breaking portion was the interface of low index layer and high index layer and antireflection material transfer failed. The reason for the failure was attributed to too much adhesion of the low index layer to the PET release layer.

Comparison Example T-3: On 75 um PET (Product name: 0-75, Teijin), Lt-3 described above was coated by Mayer bar #6 and dried in 80⁰C oven for 30 seconds and then put in 12O⁰C oven for 20 seconds to make low index layer with approximately 90 nm thickness. On the low index layer, H-I was coated by Mayer bar #8 and dried in 80⁰C oven for 30 seconds, however during drying, the organic solvent in high index layer dissolved the low index layer. As a result, some surface imperfection (pattern) was observed on the high index layer and the experiment was suspended.

Comparison Example T-4: On 75 um PET (Product name: 0-75, Teijin), Lt-3 described above was coated by Mayer bar #6 and dried in 8O⁰C oven for 30 seconds and then put in 12O⁰C oven for 20 seconds. This coated film was UV exposed for 8 seconds from the PET side with a 120 W Fusion lump (D bulb) under nitrogen gas atmosphere to make low index layer with a thickness of approximately 90 nm. However, when high index layer solution was coated on the low index layer, severe dewetting phenomenon was observed and high index layer was not constructed successfully.

Comparison Example T-5: The same procedure was employed as Example 1 except using H-2 for H-I .

In the next step, this transferable AR material and commercial acrylic board with 7 cm square and 2 mm thickness were put together and were inserted into a heat-press machine with two metal plates and heat-pressed for 40 seconds with 30 MPa pressure.

The temperatures of the plates were 180⁰C for film/acrylic side and 50°C for the opposite side. The pressed materials were taken out and PET film was removed after cooling. As a result, the anti-reflection layer was successfully transferred on the acrylic surface.

Comparison Example T-6: Commercial acrylic sheet with 2 mm thickness was used without any treatment.

For the examples and comparison examples, the following properties were evaluated:

Spectral: A black PVC sheet was put on the opposite side of the antireflection treatment by PSA and spectral reflectance at 580 nm was measured by spectrometer, F-20 (Filmetrics). For this measurement, a measurement position, where minimum reflection is located in 580 nm, were selected and used. (For blank acrylic sheet in comparison Example 6, reflectance at 580 nm was measured.)

Scratch resistance: Very fine steel wool (#0000 steel wool) was used to test a sample of the antireflection film. Samples were tested using 10 cycles of rubbing with a 400 gf/cm2 load. The samples were evaluated by naked eye observation to determine the number of scratches observed. 0 scratches indicates ideal performance, while acceptable performance is generally indicated for surface having a small portion of visible observed scratches.

Transfer performance: Transfer performance was evaluated by naked eye observation.

The results were as toiiows:

Table II

Table II illustrates how the low refractive index composition (L-I) for use in the transferable antireflection material showed good reflectance, scratch resistance and transfer performance as compared with other samples. Table 1 also illustrates the preferred factors for high refractive index composition to achieve good results. Table 1 thus shows that the preferred low refractive index and high index composition is available for use in a transferable antireflection coating.

While the invention has been described in terms of preferred embodiments, it will be understood, of course, that the invention is not limited thereto since modifications may be made by those skilled in the art, particularly in light of the foregoing teachings.

Claims

What Is Claimed Is:

1. A silicone modified fluoropolymer composition useful as low refractive index antireflection coating layer, the composition comprising the reaction product of: a fluoropolymer having at least one hexafluoropropylene monomer unit coupled to a vinylidene fluoride monomer unit; an amino silane coupling agent reacted with said one of said at least one vinylidene fluoride monomer unit; and an oligomer of a silicone alkoxy resin partially condensed with said amino silane coupling agent, wherein said oligomer of said silicone alkoxy resin comprises: Si-(ORl)mR2n wherein m is a whole number between 1 and 4 and n is a whole number between 0 and 3 such that m + n = 4; and wherein Rl and R2 are alkyl groups.

2. The composition of claim 1, wherein a portion of Rl comprises an acetyl group.

3. The composition of claim 1, wherein said fluoropolymer is selected from the group consisting of THV and FKM.

4. The composition of claim 1, wherein said amino silane coupling agent comprises an aminoalkoxysilane coupling agent.

5. The composition of claim 4, wherein said aminoalkoxysilane coupling agent comprises 3-aminopropyl methoxy silane.

' 6. The composition of claim 1, wherein said oligomer of a silicone alkoxy resin comprises a mixture of an organic alkoxy silane resin and a tetraalkoxy silane resin.

7. The composition of claim 6, wherein the weight ratio of said tetraalkoxy silane rcaiii Io bald organic aikoxy resm in said mixture is between about 2: 1 and 3:1.

8. The composition of claim 6, wherein said organic alkoxy silane resin is selected from the group consisting of an alkyl-trimethoxy silane resin and an aryl-trimethoxy silane resin.

9. The composition of claim 8, wherein said alkyl-trimethoxy silane resin comprises an fluoroalkyl-trimethoxy silane resin.

10. The composition of claim 1 further comprising a stabilizing agent.

11. The composition of claim 10, wherein said stabilizing agent comprises dibutyltin dilaurate.

12. The composition of claim 1 further comprising a plurality of inorganic particles having an average particle size of between about 5 and 100 nanometers.

13. The composition of claim 12, wherein said plurality of inorganic particles comprise a plurality of surface modified inorganic particles having an average particle size of between about 5 and 100 nanometers.

14. An article having an optical display, the optical display comprising:

(a) an optical substrate; and

(b) an antireflection coating coupled to said optical substrate, said antireflection coating comprising a high refractive index layer and a low refractive index layer, wherein said low refractive index layer comprises the reaction product of claim 1.

15. A heat transferable antireflection material comprising: a removable release layer; a low refractive index layer coupled to said removable release layer, wherein the composition of said low refractive index layer comprises the reaction product of the composition of claim 1; a lilgli refraciive inάex layer coupled to said low refractive index layer; a hard coat layer coupled to said high refractive index layer; and an adhesive layer coupled to said hard coat layer.

16. The antireflection material of claim 15, wherein said high refractive index layer comprises a mixture of high index inorganic particles and a matrix resin.

17. The antireflection material of claim 16, wherein said high index inorganic particles is selected from the group consisting of zirconium dioxide particles and titanium dioxide particles.

18. The antireflection material method of claim 16, wherein said matrix resin comprises a mixture of a multifunctional acrylate resin and a multifunctional epoxy acrylate resin.

19. The antireflection material of claim 18, wherein said multifunctional acrylate resin is selected from the group consisting of DPHA and PETA.

20. The antireflection material of claim 18, wherein said multifunctional epoxy acrylate resin is selected from the group consisting of a Bisphenol A epoxy acrylate resin and a novolac epoxy acrylate resin.

21. The antireflection material of claim 16, wherein said matrix resin comprises a silane coupling agent having an acryloyl group.

22. The antireflection material of claim 15, wherein said hard coat layer is selected from the group consisting of a UV curable multifunctional polyurethane acrylate resin, a

UV curable multifunctional acrylic monomer resin, a UV curable difunctional polyurethane acrylate resin and a UV curable difunctional acrylic monomer resin.

23. The antireflection material of claim 15, wherein said adhesive material comprises a copolymer of polyvinyl chloride and polyvinyl acetate or an acrylic polymer.

24. A method for forming an optical device having decreased glare and improved durability and stain repellency, the method comprising:

(a) providing the optical device having an optical substrate;

(b) thermally coupling said transferable antireflection material of claim 15 to said optical device such that said adhesive layer is coupled to said optical substrate; and

(c) removing said release layer from said low refractive index layer.

25. A method for forming a composition suitable for use as a low refractive index coating layer, the method comprising: providing a fluoropolymer solution comprising a fluoropolymer dissolved in a compatible organic solvent, said fluoropolymer comprising a copolymer having at least one hexafluoropropylene monomer unit coupled to a vinylidene fluoride monomer unit; modifying said fluoropolymer with an amino silane coupling agent to form an aminosilane-modified fluoropolymer; and heating and partially condensing said modified fluoropolymer with an oligomer of a silicone alkoxy resin, wherein said oligomer of silicone alkoxy resin comprises: Si-(ORl )mR2n wherein m is a whole number between 1 and 4 and n is a whole number between 0 and 3 such that m + n = 4; and wherein Rl and R2 are alkyl groups.

26. The method of claim 25, wherein providing a fluoropolymer solution comprising a fluoropolymer dissolved in a compatible organic solvent comprises: providing a fluoropolymer solution comprising a fluoropolymer dissolved in a compatible organic solvent comprises, wherein said fluoropolymer solution is about 10% by weight of said fluoropolymer and about 90% by weight of said compatible organic solvent.

27. The method of claim 25, wherein modifying said fluoropolymer with an amino silane coupling agent to form an aminosilane-modified fluoropolymer comprises: modifying said fluoropolymer with an aminoalkoxysilane coupling agent to form an aminosilane-modified fluoropolymer.

28. The method of claim 25, wherein modifying said fluoropolymer with an oligomerized amino silane coupling agent to form an aminosilane-modified fluoropolymer comprises: introducing an amino silane coupling agent to said fluoropolymer solution to form a mixture; and maintaining said mixture at room temperature for a period of time sufficient for an amine component of said amino silane coupling agent to react with said vinylidene fluoride monomer unit to form an aminosilane-modified fluoropolymer.

29. The method of claim 25, wherein heating and partially condensing said modified fluoropolymer with an oligomer of a silicone alkoxy resin comprises: introducing an oligomer of a silicone alkoxy resin to said aminosilane-modified fluoropolymer to form a mixture, said silicone alkoxy resin having the formula (Si- (0Rl)mR2n), wherein Rl and R2 are alkyl groups and wherein m is a whole number between 1 and 4 and n is a whole number between 0 and 3 such that m + n = 4; heating said mixture to an elevated temperature for a predetermined period of time sufficient such that at least one of said pendant silicone methoxy groups on said aminosilane-modified fluoropolymer condenses an alkoxy silane portion of said oligomer of said silicone alkoxy resin.

30. The method of claim 29, wherein introducing an oligomer of a silicone alkoxy resin to said aminosilane-modified fluoropolymer to form a mixture comprises: introducing an oligomer of a silicone alkoxy resin to said aminosilane-modified fluoropolymer to form a mixture, said oligomer of said silicone alkoxy resin comprising a first amount of an organic alkoxy silane resin and a second amount of a tetraalkoxy silane resin.

31. The method of claim 29, wherein introducing an oligomer of a silicone alkoxy resin to said aminosilane-modified fluoropolymer to form a mixture comprises: introducing an oligomer of a silicone alkoxy resin to said aminosilane-modified fiuoropolymer to form a mixture, said oligomer of said silicone alkoxy resin comprising a first amount of an organic alkoxy silane resin and a second amount of a tetraalkoxy silane resin, wherein the weight ratio of said tetraalkoxy silane resin to said organic alkoxy resin in said mixture is between about 2: 1 and 3:1.

32. The method of claim 25 further comprising reducing a solids content of the composition to less than about 10 percent solids by introducing a quenching solvent to said mixture.

33. The method of claim 25 further comprising introducing a stabilizing agent to said mixture.