Classifications

• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B1/00—Optical elements characterised by the material of which they are made; Optical coatings for optical elements
  • G02B1/10—Optical coatings produced by application to, or surface treatment of, optical elements
  • G02B1/11—Anti-reflection coatings
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B1/00—Optical elements characterised by the material of which they are made; Optical coatings for optical elements
  • G02B1/10—Optical coatings produced by application to, or surface treatment of, optical elements
  • G02B1/11—Anti-reflection coatings
  • G02B1/111—Anti-reflection coatings using layers comprising organic materials
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B27/00—Layered products comprising a layer of synthetic resin
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L27/00—Compositions of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Compositions of derivatives of such polymers
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B82—NANOTECHNOLOGY
  • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
  • B82Y30/00—Nanotechnology for materials or surface science, e.g. nanocomposites
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/24—Structurally defined web or sheet [e.g., overall dimension, etc.]
  • Y10T428/24942—Structurally defined web or sheet [e.g., overall dimension, etc.] including components having same physical characteristic in differing degree
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/25—Web or sheet containing structurally defined element or component and including a second component containing structurally defined particles
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/25—Web or sheet containing structurally defined element or component and including a second component containing structurally defined particles
  • Y10T428/254—Polymeric or resinous material
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/25—Web or sheet containing structurally defined element or component and including a second component containing structurally defined particles
  • Y10T428/256—Heavy metal or aluminum or compound thereof
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/26—Web or sheet containing structurally defined element or component, the element or component having a specified physical dimension
  • Y10T428/263—Coating layer not in excess of 5 mils thick or equivalent
  • Y10T428/264—Up to 3 mils
  • Y10T428/265—1 mil or less
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/26—Web or sheet containing structurally defined element or component, the element or component having a specified physical dimension
  • Y10T428/269—Web or sheet containing structurally defined element or component, the element or component having a specified physical dimension including synthetic resin or polymer layer or component
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/31504—Composite [nonstructural laminate]
  • Y10T428/3154—Of fluorinated addition polymer from unsaturated monomers
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/31504—Composite [nonstructural laminate]
  • Y10T428/31855—Of addition polymer from unsaturated monomers
  • Y10T428/31935—Ester, halide or nitrile of addition polymer

Definitions

• AR films antireflective polymer films
• the physical principles by which anti-reflection films and coatings function are well known.
• AR films are often constructed of alternating high and low refractive index ("RI") polymer layers of the correct optical thickness.
• RI refractive index
• This thickness is on the order of one-quarter of the wavelength of the light to be reflected.
• the human eye is most sensitive to light around 550 nm. Therefore it is desirable to design the low and high index coating thicknesses in a manner that minimizes the amount of reflected light in this optical range (e.g. 2.5% or lower).
• Durable antireflective films comprising a low refractive index layer and a high refractive index layer coupled to the low refractive index layer.
• the low refractive index layer comprises the reaction product of a polymerizable composition comprising at least one fluorinated free-radically polymerizable material and surface modified inorganic nanoparticles.
• the high refractive index layer preferably has a thickness of about 1 microns to about 10 microns.
• the high refractive index layer comprises surface modified inorganic nanoparticles dispersed in a crosslinked organic material.
• the high refractive index layer is an (e.g. sputter coated) inorganic material.
• the antireflective film surface exhibits a haze of less than 1.0% after 25 wipes with steel wool using a 3.2 cm mandrel and a mass of 1000 grams.
• the high refractive index layer preferably has a refractive index of at least 1.60 and preferably comprises 15 vol-% to 40 vol % surface modified zirconia nanoparticles.
• the surface modified nanoparticles preferably comprise free-radically polymerizable groups.
• the low refractive index composition typically comprises one or more fluorinated free-radically polymerizable monomers, oligomers, polymers, and mixtures thereof, having a fluorine content of at least 25 wt-%.
• the proportion of such material in the low refractive index layer is typically at least 25 wt-% or greater.
• the fluorinated free- radically polymerizable material is preferably multi-functional.
• the low refractive index layer composition typically further comprises at least one non- fluorinated crosslinker having at least three multi-acrylate groups.
• the fluorinated free-radically polymerizable material comprises at least one fluoropolymer.
• the low refractive index layer comprises the reaction product of a polymerizable composition comprising a free-radically polymerizable fluorinated polymeric intermediate, at least one fluorinated free-radically polymerizable (e.g. monomeric and/or oligomeric) material; and the surface modified inorganic nanoparticles.
• the low refractive index layer comprises the reaction product of a polymerizable composition comprising at least one free-radically polymerizable fluoropolymer, at least one amino organosilane ester coupling agent or condensation product thereof, at least one non-fluorinated crosslinker having at least three free-radically polymerizable groups; and the surface modified inorganic nanoparticles.
• the low refractive index layer is preferably cured by exposure to (e.g. UV) radiation to crosslink the free-radically polymerizable moieties.
• the low refractive index layer has an optical thickness of about 1 A wave.
• Durable antireflective films can be obtained in the absence of (e.g. matte) inorganic particles having a diameter of greater than 1 micron.
• the antireflective films described herein may be provided as a film article comprising a (e.g. high refractive index) light transmissive substrate underlying the high refractive index layer.
• the combination of high refractive index layer and low refractive index layer may be applied directly to a (e.g. display) surface.
• the substrate to which the high refractive index layer is applied may optionally include a (e.g. high refractive index) primer that may optionally include antistatic particles.
• 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 embodied antireflective film having a low refractive index layer.
• Figure 3 is an embodied antireflective film article.
• free-radically polymerizable refers to monomers, oligomers, and polymers having functional groups that participate in crosslinking reactions upon exposure to a suitable source of free radicals.
• Free-radically polymerizable groups include for example (meth)acryl groups, -SH, allyl, or vinyl.
• Preferred free-radically polymerizable monomer and oligomers typically comprise one on more "(meth)acryl" groups including (meth)acrylamides, and (meth)acrylates optionally substituted with for example fluorine and sulfur.
• a preferred (meth)acryl group is acrylate.
• Multi- (meth)acrylate materials comprise at least two polymerizable (meth)acrylate groups; whereas as mono- (meth)acrylate material has a single (meth)acrylate group.
• the multi-(meth)acrylate monomer can include two or more (meth)acrylate group at one end of the compound.
• the free-radically polymerizable fluoropolymers typically comprise functional groups reactive with (meth)acrylate or other (meth)acryl groups.
• wt-% solids refers to the sum of the components with the exception of solvent. In some instances, wt-% solids of the polymerizable organic composition is described, referred to the sum of the components with the exception of solvent and inorganic (e.g. particle) materials. Presently described are antireflective film articles having a low refractive index
• the durable antireflective film comprises a relatively thick high refractive index layer in combination with a relatively thin low refractive index layer.
• the high refractive index layer typically has a thickness of at least 0.5 microns, preferably at least 1 micron, more preferably at least 2 microns.
• the high refractive index layer typically has a thickness of no greater than 10 microns and more typically no greater than 5 microns.
• the low refractive index layer has an optical thickness of about 1 A wave. Such thickness is typically less than 0.5 microns, more typically less than about 0.2 microns and often about 90 nm to 110 nm.
• the low refractive index layer comprises the reaction product of free-radically polymerizable materials.
• the high refractive index layer comprises surface modified nanoparticles dispersed in a crosslinked organic material
• the high refractive index layer also comprises the reaction product of free- radically polymerizable materials.
• the free-radically polymerizable material will be described herein with respect to (meth)acrylate materials. However, similar results can be obtained by the use of other free-radically polymerizable groups, as known in the art.
• the low refractive index surface layer comprises the reaction product of a polymerizable low refractive index composition comprising at least one fluorinated free- radically polymerizable material and surface modified inorganic nanoparticles.
• the surface modified particles preferably having a low refractive index (e.g. less than 1.50) dispersed in a free-radically polymerized fluorinated organic material described herein.
• Various low refractive index inorganic particles are known such as metal oxides, metal nitrides, and metal halides (e.g. fluorides).
• Preferred low refractive index particles include colloidal silica, magnesium fluoride, and lithium fluoride.
• Silicas for use in the low refractive index composition are commercially available from Nalco Chemical Co., Naperville, IL under the trade designation "Nalco Collodial Silicas" such as products 1040, 1042, 1050, 1060, 2327 and 2329.
• Suitable fumed silicas include for example, products commercially available from DeGussa AG, (Hanau, Germany) under the trade designation, "Aerosil series OX-50", as well as product numbers -130, -150, and -200. Fumed silicas are also commercially available from Cabot Corp., Tuscola, IL, under the trade designations CAB-O-SPERSE 2095", “CAB-O-SPERSE A105", and "CAB-O-SIL M5".
• the fluorinated component(s) of the low refractive index layer provide low surface energy.
• the surface energy of the low index coating composition can be characterized by various methods such as contact angle and ink repellency.
• the static contact angle with water of the cured low refractive index layer is typically at least 80°. More preferably, the contact angle is at least 90° and most preferably at least 100°. Alternatively, or in addition thereto, the advancing contact angle with hexadecane is at least 50° and more preferably at least 60°.
• Low surface energy is amenable to anti-soiling and stain repellent properties as well as rendering the exposed surface easy to clean.
• the antireflective films described herein are durable.
• the durable antireflective films resist scratching after repeated contact with an abrasive material such as steel wool. The presence of significant scratching can increase the haze of the antireflective film.
• the antireflective film has a haze of less than 1.0% after 5, 10, 15, 20, or 25 wipes with steel wool using a 3.2 cm mandrel and a mass of 1000 g, according to the Steel Wool Durability Test as further described in the examples.
• the antireflective films also retain low surface energy after repeated contact with an abrasive material such as steel wool.
• the antireflective film preferably exhibits an advancing contact angle with hexadecane of at least 45°, 50°, or 60° after 5, 10, 15, 20, or 25 wipes with steel wool using a 3.8 cm diameter mandrel and a mass of 1000 grams, according to the Steel Wool Durability Testing.
• the antireflective film typically also exhibit a static contact angle with water of at least 90°, 95°, or 100° after 10 wipes, 50 wipes, 100 wipes, 200 wipes, or even 300 wipes with steel wool using a 3.8 cm diameter mandrel and a mass of 500 grams.
• durable antireflective films include the low refractive index layer as described herein in combination with a high refractive index layer that consists of a (e.g. single) thin layer of an inorganic material, such as a metal or metal oxide.
• a high refractive index layer that consists of a (e.g. single) thin layer of an inorganic material, such as a metal or metal oxide.
• Such high refractive index coatings are generally deposited by thermal evaporation, sputtering, or other vacuum deposition techniques.
• metal oxides include for example oxides of aluminum, silicon, tin, titanium, niobium, zinc, zirconium, tantalum, yttrium, cerium, tungsten, bismuth, indium, antimony, and mixtures thereof.
• a sputtered e.g.
• the high refractive index layer of the durable antireflective film preferably comprises surface modified nanoparticles (preferably having a high refractive index of at least 1.60) dispersed in a crosslinked organic material.
• a variety of (e.g. non-fluorinated) free-radically polymerizable monomers, oligomers, polymers, and mixtures thereof can be employed in the organic material of the high refractive index layer.
• the organic material of high refractive index layer comprises a non-fluorinated free-radically polymerizable material having three or more (meth)acrylate groups alone or in combination with non-fluorinated monofunctional and/or difunctional materials, such as those subsequently described with respect to the low refractive index layer.
• a non-fluorinated free-radically polymerizable material having three or more (meth)acrylate groups alone or in combination with non-fluorinated monofunctional and/or difunctional materials, such as those subsequently described with respect to the low refractive index layer.
• suitable high refractive index compositions are known such as described in Published U.S. Application Nos. 2006/0147702; 2006/0147703; 2006/0147674; and PCT Publication Nos. WO2006/073755; WO2006/073856 and WO2006/073773.
• fluorine atoms are not preferred for the high index layer, other halogens, such as bromine and iodine are useful
• Various high refractive index particles are known including for example zirconia ("ZrO 2 "), titania (“TiO 2 "), antimony oxides, alumina, tin oxides, alone or in combination. Mixed metal oxide may also be employed.
• Zirconias for use in the high refractive index layer are available from Nalco Chemical Co. under the trade designation “Nalco 00SS008” and from Buhler AG Uzwil, Switzerland under the trade designation "Buhler zirconia Z-WO sol”.
• Zirconia nanoparticle can also be prepared such as described in U.S. Patent Publication No. 2006/0148950 and U.S. Patent No. 6,376,590.
• inorganic nanoparticles in the low refractive index layer and/or the high refractive index layer is typically at least 5 vol-%, and preferably at least 15 vol-%.
• concentration of inorganic particle is typically no greater than about 50 vol-%, and more preferably no greater than 40 vol-%.
• the inorganic nanoparticles are preferably treated with a surface treatment agent.
• Surface-treating the nano-sized particles can provide a stable dispersion in the polymeric resin.
• the surface-treatment stabilizes the nanoparticles so that the particles will be well dispersed in the polymerizable resin and results in a substantially homogeneous composition.
• the nanoparticles can be modified over at least a portion of its surface with a surface treatment agent so that the stabilized particle can copolymerize or react with the polymerizable resin during curing.
• the incorporation of surface modified inorganic particles is amenable to covalent bonding of the particles to the free-radically polymerizable organic components, thereby providing a tougher and more homogeneous polymer/particle network.
• a surface treatment agent has a first end that will attach to the particle surface (covalently, ionically or through strong physisorption) and a second end that imparts compatibility of the particle with the resin and/or reacts with resin during curing.
• surface treatment agents include alcohols, amines, carboxylic acids, sulfonic acids, phosphonic acids, silanes and titanates.
• the preferred type of treatment agent is determined, in part, by the chemical nature of the metal oxide surface. Silanes are preferred for silica and other for siliceous fillers. Silanes and carboxylic acids are preferred for metal oxides such as zirconia.
• the surface modification can be done either subsequent to or concurrent with mixing with the monomers.
• silanes it is preferred in the case of silanes to react the silanes with the particle or nanoparticle surface before incorporation into the resin.
• the required amount of surface modifier is dependant upon several factors such particle size, particle type, modifier molecular wt, and modifier type. In general it is preferred that approximately a monolayer of modifier is attached to the surface of the particle. The attachment procedure or reaction conditions required also depend on the surface modifier used. For silanes it is preferred to surface treat at elevated temperatures under acidic or basic conditions for from 1-24 hr approximately. Surface treatment agents such as carboxylic acids may not require elevated temperatures or extended time.
• surface treatment agents suitable for the compositions include compounds such as, for example, isooctyl trimethoxy-silane, N-(3- triethoxysilylpropyl) methoxyethoxyethoxy ethyl carbamate, N-(3- triethoxysilylpropyl) methoxyethoxyethoxy ethyl carbamate, 3- (methacryloyloxy)propyltrimethoxysilane, 3- acryloxypropyltrimethoxysilane, 3 -(methacryloyloxy)propyltriethoxysilane, 3 - (methacryloyloxy) propylmethyldimethoxysilane, 3 -(aery loy loxypropy l)methy ldimethoxy silane ,
• the surface modification of the particles in the colloidal dispersion can be accomplished in a variety known ways, such as described in previously cited Published U.S. Patent Application No. 2006/0148950 and U.S. Patent No. 6,376,590.
• a combination of surface modifying agents can be useful, wherein at least one of the agents has a functional group co-polymerizable with a hardenable resin. Combinations of surface modifying agent can result in lower viscosity.
• the polymerizing group can be ethylenically unsaturated or a cyclic function subject to ring opening polymerization.
• An ethylenically unsaturated polymerizing group can be, for example, an acrylate or methacrylate, or vinyl group.
• a cyclic functional group subject to ring opening polymerization generally contains a heteroatom such as oxygen, sulfur or nitrogen, and preferably a 3-membered ring containing oxygen such as an epoxide.
• a preferred combination of surface modifying agent includes at least one surface modifying agent having a functional group that is copolymerizable with the organic component of the polymerizable resin and a second amphiphilic modifying agent, such as a poly ether silane, that may act as a dispersant.
• the second modifying agent is preferably a polyalkyleneoxide containing modifying agent that is optionally co-polymerizable with the organic component of the polymerizable composition.
• Surface modified colloidal nanoparticles can be substantially fully condensed. Non-silica containing fully condensed nanoparticles typically have a degree of crystallinity (measured as isolated metal oxide particles) greater than 55%, preferably greater than 60%, and more preferably greater than 70%.
• the degree of crystallinity can range up to about 86% or greater.
• the degree of crystallinity can be determined by X-ray diffraction techniques. Condensed crystalline (e.g. zirconia) nanoparticles have a high refractive index whereas amorphous nanoparticles typically have a lower refractive index.
• 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 particles can be introduced having a range of particle sizes obtained by grinding the particles to a desired size range.
• the inorganic oxide particles are typically non-aggregated (substantially discrete), as aggregation can result in optical scattering (haze) or precipitation of the inorganic oxide particles or gelation.
• the inorganic oxide particles are typically colloidal in size, having an average particle diameter of 5 nanometers to 100 nanometers.
• the particle size of the high index inorganic particles is preferably less than about 50 nm in order to provide sufficiently transparent high-refractive index coatings.
• 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.
• the antireflective film may have a gloss or matte surface. Matte antireflective films typically have lower transmission and higher haze values than typical gloss films. For examples the haze is generally at least 5%, 6%, 7%, 8%, 9%, or 10% as measured according to ASTM D 1003. Whereas gloss surfaces typically have a gloss of at least 130 as measured according to ASTM D 2457-03 at 60 °; matte surfaces have a gloss of less than 120.
• the surface can be roughened or textured to provide a matte surface. This can be accomplished in a variety of ways as known in the art including embossing the low refractive index surface together with the underlying layer(s) with a suitable tool that has been bead-blasted or otherwise roughened, as well as by curing the composition against a suitable roughened master as described in U.S. Pat. Nos. 5,175,030 (Lu et al.) and 5,183,597 (Lu).
• matte antireflective films can be prepared by providing the high refractive index layer and low refractive index (e.g. surface) layer on a matte film substrate. Exemplary matte films are commercially available from U.S.A.
• Matte low and high refractive index coatings can also be prepared by adding a suitably sized particle filler such as silica sand or glass beads to the composition.
• a suitably sized particle filler such as silica sand or glass beads
• Such matte particles are typically substantially larger than the surface modified low refractive index particles.
• the average particle size typically ranges from about 1 to 10 microns.
• the concentration of such matte particles may range from at least 2 wt-% to about 10 wt-% or greater. At concentrations of less than 2 wt-% (e.g.
• the low refractive index polymerizable composition and organic high refractive index polymerizable composition generally comprise at least one crosslinker having at least three free-radically polymerizable groups. This component is often a non-fluorinated multi- (meth)acrylate monomer. The inclusion of such material contributes to the hardness of the cured compositions.
• the low refractive index and organic high refractive index polymerizable compositions typically comprise at least 5 wt-%, or 10 wt-%, or 15 wt-% of crosslinker.
• the concentration of crosslinker in the low refractive index composition is generally no greater than about 40 wt-%.
• the concentration of crosslinker in the high refractive index composition is generally no greater than about 25 wt-%.
• Suitable monomers include for example trimethylolpropane triacrylate (commercially available from Sartomer Company, Exton, PA under the trade designation "SR351”), ethoxylated trimethylolpropane triacrylate (commercially available from Sartomer Company, Exton, PA under the trade designation "SR454"), pentaerythritol tetraacrylate, pentaerythritol triacrylate (commercially available from Sartomer under the trade designation "SR444"), dipentaerythritol pentaacrylate (commercially available from Sartomer under the trade designation "SR399”), ethoxylated pentaerythritol tetraacrylate, ethoxylated pentaerythritol triacrylate (from Sartomer under the trade designation "SR494") dipentaerythritol hexaacrylate, and tris(2-hydroxy ethyl) isocyanurate triacrylate (from Sartomer under the
• the low and high refractive index polymerizable coating compositions may further comprise at least one difunctional (meth) aery late monomer.
• difunctional (meth)acrylate monomers are known in the art, including for example 1, 3 -butylene glycol diacrylate, 1 ,4-butanediol diacrylate, 1 ,6-hexanediol diacrylate, 1,6-hexanediol monoacrylate monomethacrylate, ethylene glycol diacrylate, alkoxylated aliphatic diacrylate, alkoxylated cyclohexane dimethanol diacrylate, alkoxylated hexanediol diacrylate, alkoxylated neopentyl glycol diacrylate, caprolactone modified neopentylglycol hydroxypivalate diacrylate, caprolactone modified neopentylglycol hydroxypivalate diacrylate, cyclohexanedimethanol
• the low refractive index layer preferably comprises one or more free-radically polymerizable materials having a fluorine content of at least 25 wt-%.
• Highly fluorinated monomer, oligomers, and polymers are characterized by having a low refractive index.
• Various fluorinated multi- and mono- (meth)acrylate materials having a fluorine content of at least about 25 wt-% are known.
• the low refractive polymerizable composition has a fluorine content of at least 30 wt-%, at least 35 wt-%, at least 40 wt-%, at least 45 wt-%, or at least 50 wt-%.
• a major portion of the high fluorinated material is a multifunctional free-radically polymerizable material. However, such materials can be used in combination with fluorinated mono- functional materials.
• fluorinated mono- and multi- (meth)acrylate compounds may be employed in the preparation of the polymerizable low refractive index coating composition.
• Such materials generally comprise free-radically polymerizable moieties in combination with (per)fluoropolyether moieties, (per)fluoroalkyl moieties, and (per)fluoroalkylene moieties.
• species having a high fluorine content e.g. of at least 25 wt- %).
• Other species within each class, having fluorine content less than 25 wt-% can be employed as auxiliary components.
• such auxiliary fluorinated (meth)acrylate monomers can aid in compatibilizing the low refractive index or other fluorinated materials present in the reaction mixture.
• perfluoropolyether urethane compounds have been found to be particularly useful for compatibilizing high fluorine containing materials such as described in Published U.S. Patent Application No. 2006/0216524; U.S. Application Serial No. 11/277162, filed March 22, 2006; and Application Serial No. 11/423782, filed June 13, 2006.
• Such perfluoropolyether urethane compounds generally include at least one polymerizable (e.g.
• the urethane and urea linkage is typically -NHC(O)X- wherein X is O, S or NR; and R is H or an alkyl group having 1 to 4 carbon.
• the perfluoropolyether moiety is preferably a HFPO- moiety ,wherein HFPO is F(CF(CF 3 )CF 2 O)aCF(CF 3 )- and "a" averages 2 to 15. In some embodiment "a" averages about 4 or 6. .
• the low refractive index polymerizable composition comprises at least one free-radically polymerizable fluoropolymer.
• a general description and preparation of these classes of fluoropolymers can be found in Encyclopedia of Chemical Technology, Fluorocarbon Elastomers, Kirk-Othmer (1993), or in Modern Fluoropolymers, J. Scheirs Ed, (1997), J Wiley Science, Chapters 2, 13, and 32. (ISBN 0- 471-97055-7).
• TFE tetrafluoroethylene
• HFP hexafluoropropylene
• VDF vinylidene fluoride
• FKM Amorphous copolymers consisting of VDF-HFP and optionally TFE are hereinafter referred to as FKM, or FKM elastomers as denoted in ASTM D 1418.
• FKM elastomers have the general formula:
• x, y and z are expressed as molar percentages.
• x can be zero so long as the molar percentage of y is sufficiently high (typically greater than about 18 molar percent) to render the microstructure amorphous. Additional fluoroelastomer compositions useful in the present invention exist where x is greater than zero.
• the fluoropolymer comprises free-radically polymerizable groups. This can be accomplished by the inclusion of halogen-containing cure site monomers (“CSM”) and/or halogenated endgroups, which are interpolymerized into the polymer using numerous techniques known in the art. These halogen groups provide reactivity towards the other components of coating mixture and facilitate the formation of the polymer network.
• CSM halogen-containing cure site monomers
• halogenated endgroups which are interpolymerized into the polymer using numerous techniques known in the art.
• halogen groups provide reactivity towards the other components of coating mixture and facilitate the formation of the polymer network.
• Useful halogen-containing monomers are well known in the art and typical examples are found in U.S. Patent No. 4,214,060 to maschiner et al, European Patent No. EP398241 to Moore, and European Patent No. EP407937B1 to Vincenzo et al.
• halogen cure sites can be introduced into the polymer structure via the use of halogenated chain transfer agents which produce fluoropolymer chain ends that contain reactive halogen endgroups.
• chain transfer agents are well known in the literature and typical examples are: Br-CF 2 CF 2 -Br, CF 2 Br 2 , CF 2 I 2 , CH 2 I 2 .
• Other typical examples are found in U.S. Patent No. 4,000,356 to Weisgerber.
• Whether the halogen is incorporated into the polymer microstructure by means of a cure site monomer or chain transfer agent or both is not particularly relevant as both result in a fluoropolymer which is more reactive towards UV crosslinking and coreaction with other components of the network such as the acrylates.
• a bromo-containing fluoroelastomer such as Dyneon TM E-15742, E-18905, or E-18402 available from Dyneon LLC of St. Paul, Minnesota, may be used in conjunction with, or in place of, FKM as the fluoropolymer.
• the fluoropolymer can be rendered reactive by dehydrofluorination by any method that will provide sufficient carbon-carbon unsaturation of the fluoropolymer to create increased bonding between the fluoropolymer and a hydrocarbon substrate or layer.
• the dehydrofluorination process is a well-known process to induce unsaturation and it is used most commonly for the ionic crosslinking of fluoroelastomers by nucleophiles such as diphenols and diamines. This reaction is characteristic of VDF containing elastomers.
• a descriptions can be found in The Chemistry of Fluorocarbon Elastomers, A.L. Logothetis, Prog. Polymer Science (1989), 14, 251.
• the fluoropolymer containing low refractive index composition described herein preferably comprise at least one amino organosilane ester coupling agent or a condensation product thereof as described in U.S. Publication No. 2006/0147723.
• Preferred amino organosilane ester coupling agent include 3- aminopropyltrimethoxysilane, 3 -aminopropyltriethoxysilane, (aminoethylaminomethyl)phenethyltrimethoxysilane,
• aminoethylaminomethylphenethyltriethoxysilane N-(2-aminoethyl)-3- aminopropy lmethyldimethoxysilane, N-(2-aminoethyl)-3 - aminopropy lmethyldiethoxysilane, N-(2-aminoethyl)-3 -aminopropyltrimethoxysilane, N- (2-aminoethyl)-3-aminopropyltriethoxysilane, 4-aminobutyltrimethoxysilane, A- aminobutyltriethoxysilane, 3-aminopropylmethyldiethoxysilane, 3- aminopropy lmethyldimethoxysilane, 3 -aminopropyldimethylmethoxysilane, 3 - aminopropyldimethylethoxysilane, 2,2-dimethoxy- 1 -aza-2-silacyclopentane-
• the low refractive index layer comprises the reaction product of a A) fluoro(meth)acrylate polymeric intermediate and B) at least one fluorinated (meth)acrylate monomer as described in U.S. Serial No. 11/423791, filed June 13, 2006.
• the mixture of A) and B) is preferably cured by exposure to (e.g. ultraviolet light) radiation.
• the cured low refractive index polymeric composition may comprise copolymerization reaction products of A) and B).
• the cured low refractive index polymeric composition is surmised to also comprise polymerization products of B).
• the fluoro (meth)acrylate polymer intermediate may covalently bond to other components within the low refractive index coating composition.
• non-fluorinated crosslinker may polymerize physically entangling the fluoro (meth)acrylate polymer intermediate thereby forming an interpenetrating network.
• the A) fluoro (meth)acrylate polymeric intermediate comprises the reaction product of i) at least one fluorinated multi- (meth)acrylate monomer or oligomer having a fluorine content of at least about 25 wt-%; and ii) optionally one or more fluorinated or non-fluorinated multi-(meth)acrylate materials.
• the optional multi-(meth) acrylate material may include a monomer, oligomer, polymer, surface modified inorganic nanoparticles having multi-(meth)acrylate moieties, as well as the various combinations of such materials.
• the total amount of multi- (meth)acrylate materials is generally at least 25 wt-% based on wt-% solids of the polymerizable organic composition.
• the total amount of multi- (meth)acrylate materials may range from about 30 wt-% to 70 wt-% of the nanoparticle containing composition.
• the low refractive index composition may comprise various monofunctional and/or multi-functional HFPO- perfluoropolyether compounds.
• the inclusion of at least about 5 wt-% to about 10 wt-% of these materials in the low refractive index layer can provide low energy surfaces having an initial static contact angle with water of at least 110°.
• Various perfluoropolyether mono- (meth)acrylate compounds are known.
• This monomer can be prepared as described in U.S. Patent Application Publication No. 2005/0249940-A1. (See FC-4).
• These compounds can be prepared as described in the Published U.S. Patent Application No. 2006/0216524 and Pending U.S. Application Serial No. 11/277162, filed March 22, 2006 (See Preparations No. 28. and 30).
• At least one free-radical initiator is typically utilized for the preparation of the polymerizable low and high refractive coating compositions.
• Useful free-radical thermal initiators include, for example, azo, peroxide, persulfate, and redox initiators, and combinations thereof.
• Useful free-radical photoinitiators include, for example, those known as useful in the UV cure of acrylate polymers.
• other additives may be added to the final composition. These include but are not limited to resinous flow aids, photostabilizers, high boiling point solvents, and other compatibilizers well known to those of skill in the art.
• the polymerizable compositions can be formed by dissolving the free-radically polymerizable material(s) in a compatible organic solvent at a concentration of about 1 to 10 percent solids.
• a compatible organic solvent at a concentration of about 1 to 10 percent solids.
• suitable solvents include alcohols such as isopropyl alcohol (IPA) or ethanol; ketones such as methyl ethyl ketone (MEK), methyl isobutyl ketone (MIBK), diisobutyl ketone (DIBK); cyclohexanone, or acetone; aromatic hydrocarbons such as toluene; isophorone; butyrolactone; N-methylpyrrolidone; tetrahydrofuran; esters such as lactates, acetates, including propylene glycol monomethyl ether acetate such as commercially available from 3M under the trade designation "3M Scotchcal Thinner CGSlO" ("CGSlO)
• compatible low refractive index coating compositions are prepared that are free of fluorinated solvents.
• Compatible coating compositions are clear, rather than hazy.
• Compatible coatings are substantially free of visual defects. Visual defects that may be observed when incompatible coating are employed include but are not limited to haze, pock marks, f ⁇ sheyes, mottle, lumps or substantial waviness, or other visual indicators known to one of ordinary skill in the art in the optics and coating fields.
• the method of forming an antireflective coating on an optical display or an antireflective film for use of an optical display may include providing a light transmissible substrate layer; providing a high refractive index material on the substrate layer; and providing the low index layer described herein coupled to the high refractive index layer.
• the low index layer may be provided by applying a layer of said low refractive index material onto said (e.g. cured) layer of said high refractive index material and irradiating with a sufficient ultraviolet radiation to crosslink.
• the low refractive index coating may be applied to a release liner, at least partially cured, and transfer coated onto the high index layer.
• the antireflection material may be applied directly to the substrate or alternatively applied to a release layer of a transferable antireflection film and subsequently transferred from the release layer to the substrate using a thermal or radiation-induced transfer. Suitable transfer methods are described in Published U.S. Application No. 2006/0147614.
• the low refractive index composition and high refractive index composition can be applied as a single or multiple layers to a high refractive index layer or directly to a (e.g. display surface or film) substrate using conventional film application techniques.
• a combination of low reflectance and good durability can be obtained with a single low refractive index layer provided on a single high refractive index layer.
• Thin films can be applied using a variety of techniques, including dip coating, forward and reverse roll coating, wire wound rod coating, and die coating.
• Die coaters include knife coaters, slot coaters, slide coaters, fluid bearing coaters, slide curtain coaters, drop die curtain coaters, and extrusion coaters among others. Many types of die coaters are described in the literature such as by Edward Cohen and Edgar Gutoff, Modern Coating and Drying Technology, VCH Publishers, NY 1992, ISBN 3-527-28246-7 and Gutoff and Cohen, Coating and Drying Defects: Troubleshooting Operating Problems, Wiley Interscience, NY ISBN 0-471-59810-0.
• the coatings may be applied to individual sheets.
• the low refractive index as well as high refractive index coating composition are dried in an oven to remove the solvent and then cured for example by exposure to ultraviolet radiation using an H-bulb or other lamp at a desired wavelength, preferably in an inert atmosphere (less than 50 parts per million oxygen).
• the reaction mechanism causes the free-radically polymerizable materials to crosslink.
• FIG. 1 a perspective view of an article (here a computer monitor 10) having an optical display 12 disposed within a housing 14.
• the optical display 12 comprises a substantially transparent material through which a user can view text, graphics or other displayed information.
• the display substrate 12 is light transmissive, meaning light can be transmitted through the display substrate 12 such that the display can be viewed. Both transparent (e.g. gloss) and matte light transmissive substrates 12 are employed in display panels.
• the display substrate 12 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), and polyolefms such as biaxially oriented polypropylene which are commonly used in various optical devices.
• PET polyethylene terephthalate
• polyolefms such as biaxially oriented polypropylene which are commonly used in various optical devices.
• the optical display 12 includes an antireflection film 18 having at least one layer of a high refractive index layer 22 and a low refractive index layer 20.
• the low refractive index layer 20 is provided between the high refractive index layer and the viewing surface.
• Low refractive index layer 20 is typically a surface layer exposed to the environment, as depicted in FIG. 2.
• the high refractive index layer has a refractive index of at least about 1.4, and typically at least about 1.5.
• the maximum refractive index of the high index layer is typically no greater than about 1.75 for coatings having high refractive index inorganic nanoparticles dispersed in a crosslinked organic material.
• the low refractive index layer has a refractive index less than a high refractive index layer.
• the difference in refractive index between the high refractive index layer and low refractive index layer is typically at least 0.10, or 0.15, or 0.2 or greater.
• the low refractive index layer typically has a refractive index of less than about 1.5, more typically of less than about 1.45, and even more typically less than about 1.42.
• the minimum refractive index of the low index layer is generally at least about 1.35.
• Antireflective films preferably have an average reflectance of less than 3%, 2%, or 1% at 450 nm to 650 nm as measured with a spectrophotometer as described in the examples.
• an embodied antireflective film article typically comprises a light transmissive substrate 16.
• the substrate 16 as well as the antireflective film typically have a transmission of at least 80%, at least 85%, and preferably at least 90%.
• the high refractive index layer 22 is disposed between the film substrate 16 and low refractive index layer 20.
• the antireflective film may comprise other layers.
• Various permanent and removable grade adhesive compositions 30 may be provided on the opposite side of the film substrate 16.
• the antireflective film article typically include a removable release liner 40. During application to a display surface, the release liner is removed so the antireflective film article can be adhered to the display surface.
• Suitable adhesive compositions include (e.g. hydrogenated) block copolymers such as those commercially available from Kraton Polymers, Westhollow, TX under the trade designation "Kraton G-1657", as well as other (e.g. similar) thermoplastic rubbers.
• Other exemplary adhesives include acrylic-based, urethane-based, silicone-based and epoxy- based adhesives.
• Preferred adhesives are of sufficient optical quality and light stability such that the adhesive does not yellow with time or upon weather exposure so as to degrade the viewing quality of the optical display.
• the adhesive can be applied using a variety of known coating techniques such as transfer coating, knife coating, spin coating, die coating and the like. Exemplary adhesives are described in U.S. Patent Application Publication No. 2003/0012936. Several of such adhesives are commercially available from 3M Company, St. Paul, MN under the trade designations 8141, 8142, and 8161.
• the antireflective film substrate 16 is selected based in part on the desired optical and mechanical properties such as flexibility, dimensional stability and impact resistance.
• Substrate 16 may comprise any of the same thermoplastic and crosslinked polymeric materials as optical display 12.
• Substrate 16 may also comprise or consist of polyamides, polyimides, phenolic resins, polystyrene, styrene-acrylonitrile copolymers, epoxies, and the like.
• the substrate 16 may comprise a hybrid material, having both organic and inorganic components.
• the film substrate 16 thickness typically also will depend on the intended use. For most applications, the substrate thicknesses is preferably less than about 0.5 mm, and more preferably about 0.02 to about 0.2 mm.
• 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 adjacent layer, e.g., chemical treatment, corona treatment such as air or nitrogen corona, plasma, flame, or actinic radiation.
• corona treatment such as air or nitrogen corona, plasma, flame, or actinic radiation.
• an optional tie layer or primer can be applied to the substrate and/or hardcoat layer to increase the interlayer adhesion.
• Various light transmissive optical films suitable for use as the film substrate 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, January 29, 2004.
• multilayer optical films provide desirable transmission and/or reflection properties at least partially by an arrangement of microlayers of differing refractive index.
• the micro layers 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.
• each microlayer 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 ⁇ m.
• 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.
• 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 antireflective film substrate has a refractive index close to that of the high refractive index layer, i.e. differs from the high refractive index layer by less than 0.05, and more preferably less than 0.02.
• optical fringing can be eliminated or reduced by providing a high index primer on the film substrate, the primer being chosen to closely match the refractive index of the high refractive index layer and substrate.
• the difference in refractive index between the high refractive index layer and the substrate can range from about 0.05 to 0.10 and greater.
• a primer coating is applied to either the display substrate surface, film substrate, or hardcoat layer applied to either the display substrate or film substrate.
• One preferred primer coating material for use in these constructions is availabe from Sumitomo Osaka Cement under the trade designation "Sumicefme TM-AS-I".
• This material is an aqueous dispersion containing conductive antimony tin oxide nanoparticles and a polyester binder.
• a substrate film such as PET
• it yields a high- refractive index coating (RI ⁇ 1.67) that closely matches the refractive index of the high- index hardcoat applied as the next layer.
• the primer can also improve adhesion of the high-index hardcoat to the PET substrate film, relative to uncoated PET film.
• the antimony tin oxide nanoparticles provide good antistatic performance (static charge decay times 0.01-0.02 sec) after application of the high-index hardcoat.
• antistatic materials may be incorporated in the antireflective films described herein such as described in U.S. Patent Application Serial No. 11/278172 and provisional application nos. 60/804784, filed June 14, 2006, 60/804787, filed June 14, 2006 and 60/804774, filed June 14, 2006.
• the antireflective films described herein are suitable for application to optical displays ("displays”).
• the displays include various illuminated and non-illuminated display panels.
• Such displays include multi-character and especially multi-line multicharacter 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.
• LCDs liquid crystal displays
• CRTs cathode ray tubes
• LEDs light emitting tubes
• the antireflective film can be employed with a variety of portable and nonportable information display articles.
• These articles include, but are not limited to, PDAs, LCD-TV's (both edge-lit and direct-lit), 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, and instrument panel covers. These devices can have planar or curved viewing faces.
• the antireflective material can be employed on a variety of other articles as well such as for example camera lenses, eyeglass lenses, binocular lenses, mirrors, retroreflective sheeting, automobile windows, building windows, train windows, boat windows, aircraft windows, vehicle headlamps and taillights, display cases, eyeglasses, overhead projectors, stereo cabinet doors, stereo covers, watch covers, as well as optical and magneto-optical recording disks, and the like.
• the antireflective film may also be applied to a variety of other articles including (e.g. retroreflective) signage and commercial graphic display films employed for various advertising, promotional, and corporate identity uses.
• Static contact angles were measured by suspending a water droplet from the needle tip of the dispensing syringe, then bringing the substrate surface to be measured up to the drop until the drop detached from the needle and was transferred to the surface. The drop image was then captured and the contact angle measured by image analysis. Advancing and receding contact angles were measured by adding (for advancing) or withdrawing (for receding) liquid from a droplet already in contact with the surface, and capturing the drop image as the liquid front advanced or receded across the substrate surface. Drop volumes were 5 ⁇ L for static measurements and 1-3 ⁇ L for advancing and receding. For hexadecane, only advancing and receding contact angles are reported because in most cases static and advancing values were found to be nearly equal. Haze and Transmission Measurements:
• Haze and transmission measurements were collected by means of a BYK-Gardner haze meter (BYK-Gardner USA, Columbia, Maryland).
• the Average % Reflectance of the first (i.e. front) surface of the cured films was measured using a Shimadzu UV-3101PC UN-VIS-NIR Scanning Spectrophotometer with the machine extension, MPC 3100, available from Shimadzu Co., Japan and Shimadzu Scientific Instruments, Columbia, MD.
• One sample of each film was prepared by applying Yamato Black Vinyl Tape #200-38 (obtained from Yamato International Corporation, Woodhaven, MI) to the backside of the sample.
• the black tape was laminated to the backside of the sample using a roller to ensure there were no air bubbles trapped between the black tape and the sample.
• the sample was placed in the Shimadzu Spectrophotometer so that the non-tape side was against the aperture.
• the presence of the black tape eliminates back surface reflections.
• the Reflectance was measured at a 12° incident angle between the wavelengths of 360 to 800 nm and the Average % Reflectance was calculated for the wavelength range of 450- 650 nm. Each sample was measured before and after steel wool testing.
• the abrasion resistance of the cured films was tested cross-web to the coating direction by use of a mechanical device capable of oscillating a steel wool sheet adhered to stylus across the film's surface.
• the stylus oscillated over a 60 mm wide sweep width at a rate of 210 mm/sec (3.5 wipes/sec) wherein a "wipe" is defined as a single travel of 60 mm.
• the stylus had a flat, cylindrical base geometry with a diameter of 3.2 cm.
• the stylus was designed for attachment of weights to increase the force exerted by the steel wool normal to the film's surface.
• the #0000 steel wool sheets were "Magic Sand-Sanding Sheets" available from Hut Products Fulton, MO.
• the #0000 has a specified grit equivalency of 600-1200 grit sandpaper.
• the 3.2 cm steel wool discs were die cut from the sanding sheets and adhered to the 3.2 cm stylus base with 3M Brand Scotch Permanent Adhesive Transfer tape. Ingredients Employed in the Examples
• HFPO- refers to the end group F(CF(CF3)CF2O) a CF(CF3)- of the methyl ester F(CF(CF3)CF2O) a CF(CF3)C(O)OCH3, wherein a averages about 6.22, with an average molecular weight of 1,211 g/mol. It was prepared according to the method reported in U.S. Pat. No. 3,250,808 (Moore et al.), with purification by fractional distillation.
• HFPO-C(O)N(H)CH 2 CH 2 CH 2 N(H)CH 3 was prepared according to the procedure found in US Published Application No. 2005/025092 IAl, Preparation FCl /AMI.
• HFPO-TMPTA refers to the Michael's adduct of HFPO- C(O)N(H)CH 2 CH 2 CH 2 N(H)CH 3 (FC I/AM 1) with trimethylolpropane triacrylate (TMPTA).
• This adduct was made as described in US Published Application No. 2005/0250921 , Example 1 , as the preparation of an approximately 1 : 1 molar ratio adduct of FC I/AM 1 with AC-I(TMPTA) or FC I/AM I/AC- 1. This adduct has 52.02 wt-% fluorine and nominal Mn of 1563 g/mole.
• C6DIACRY is the trade designation for 2,2,3,3 ,4,4,5,5-octafluoro-l,6-hexanediol diacrylate (commonly referred to as 8F-HDDA), having a molecular weight of 370.2 g/mole and at least 40 wt-% fluorine was obtained from Exfluor Research Corporation, of Round Rock, Texas.
• CN 4000 was obtained from Sartomer Company, Exton, PA.
• Br-FKM is a free-radically polymerizable amorphous terpolymer of tetrafluoroethylene (TFE), vinylidene fluoride (VDF) and hexafluoropropylene (HFP), and a halogen-containing cure site monomer having 70 wt.% fluorine, and available from Dyneon LLC of Oakdale, MN.
• Al 106 is the trade designation for 3-aminopropyltrimethoxysilane, manufactured by Osi Specialties (GE Silicones) of Paris, France.
• Darocur 1173 is the trade designation for 2-hy droxy-2 -methyl- 1 -phenyl- 1-propanone, a UV photoinitiator, and was obtained from Ciba Specialty Products, of Tarrytown, New York, and used as received.
• Irgacure 184 is the trade designation for 1-hydroxy-cyclohexylphenyl ketone, and was obtained from CIBA Specialty Chemicals, of Tarrytown, New York.
• HMDS is the trade designation for hexamethydisilizane available from Aldrich Co.
• KB-I is the trade designation for benzyl dimethyl ketal UV photoinitator obtained from Sartomer Company of Exton, Pennsylvania and was used as received.
• Nalco 2327 is the trade designation for an aqueous dispersion of 20 nm silica nanoparticles (41% solids in water, stabilized with ammonia), and was obtained from Nalco Chem. Co., of Naperville, Illinois.
• Prostab 5198 is the trade designation for 4-hydroxy-2,2,6,6-tetramethyl-l-piperidinyloxy (commonly referred to as 4-hydroxy-TEMPO), and was obtained from CIBA Specialty Chemicals, of Tarrytown, New York.
• 3-methacryloxypropyltrimethoxysilane is available from Alfa Aesar, Ward Hill, MA (Stock # 30505) and was used as received.
• SR399 is the trade designation for dipentaerythritol pentaacrylate (molecular weight of 525 g/mole), a non-fluorinated multifunctional (meth)acrylate monomer obtained from Sartomer Company, of Exton, Pennsylvania.
• Vazo 52 is the trade designation for 2,2',-azobis(2,4-dimethylpentane nitrile), a thermal free-radical initiator obtained from DuPont, of Wilmington, Delaware.
• ZrO 2 sols (40.8% solids in water) was prepared were prepared in accordance with the procedures described in published U.S. Patent Application No. 2006/0204745 that claims priority to U.S. Patent Application Serial No. 11/078468 filed March 11, 2005.
• the resulting ZrO 2 sols were evaluated with Photo Correlation Spectroscopy (PCS), X-Ray Diffraction and Thermal Gravimetric Analysis as described in published U.S. Patent Application No. 2006/0204745 and pending U.S. Application Serial No. 11/078468.
• the ZrO 2 sols used in the examples had properties in the ranges that follow:
• 3-methacryloxypropyltrimethoxysilane was added slowly to the reactor with stirring.
• the reaction mixture was heated under vacuum (24-40 torr) and the l-methoxy-2- propano I/water azeotrope was distilled off to remove substantially all of the water, while slowly adding 70.5 lbs of additional l-methoxy-2-propanol. 0.4 lbs of 30% ammonium hydroxide was added to the reaction mixture, then the reaction was concentrated to 59.2% solids by distilling off l-methoxy-2-propanol.
• the surface modification reaction resulted in a mixture containing 59.2% surface modified zirconia (ZrO 2 -SM), by weight, in 1- methoxy-2-propanol.
• the final mixture was filtered through a 1 micron filter.
• High Refractive Index Formulation A hardcoat formulation was prepared, as follows, as the High Refractive Index
• the reaction mixture was heated under vacuum and the l-methoxy-2-propano I/water azeotrope was distilled off with any necessary addition of l-methoxy-2-propanol to remove substantially all of the water.
• the surface modification reaction resulted in a mixture containing 40% surface modified silica (20 nm average particle size), by weight, in l-methoxy-2-propanol.
• a hyperbranched copolymer was made as follows. 17.01 grams of C6DIACRY, 8.51 grams of CN4000, 2.84 grams of SR399, 1.70 grams of HFPO-TMPTA, 241.02 grams of ethyl acetate, 25.52 grams of methyl ethyl ketone, and 3.40 grams of Vazo 52 predissolved in the methyl ethyl ketone were charged into a reaction vessel. It is preferable to add the HFPO-TMPTA to the CN4000 first, then the remaining reagents.
• the contents of the reaction vessel were degassed under nitrogen, and then heated 80 0 C in a sealed bottle for 1 to 1.5 hours. Care must be taken to avoid building an excessive molecular weight and gelling the reaction contents.
• concentration of the reactive species in the reaction mixture, the temperature of the reaction, and the reaction time were all selected to ensure this result, and one or more of these would need to be adjusted if different reactive species were used.
• the High Refractive Index Formulation containing the zirconia nanoparticles (optionally filtered through a 1 micron filter followed by a 0.2 micron filter) was coated onto either the primed surface of a 5 mil PET film (obtained from Dupont under the trade designation "Melinex 618") or 7 mil Polycarbonate film (obtained from GE, Mount Vernon, IN).
• the solution was syringe-pumped into a 4 inch wide coating die, and the coating was dried by passing through two 10 foot ovens each set at 120 0 C.
• the coating on the primed PET was then partially cured with a Light Hammer 6 UV source (Fusion UV Systems, Inc., Gaithersburg, Maryland), at 50% power.
• the resulting partially cured high refractive index layer was approximately 4 microns thick.
• the coating on the PC was fully cured with the Light Hammer 6 UV source set at 100% power, under Nitrogen.
• the resulting fully cured high refractive index layer was approximately 4 microns thick. Further details of the process conditions are included in the table below.
• Measurement of the UV output of the UV lamp at 100% UV at a line speed of 10 feet/per/minute resulted in the following energy and power readings for the UV A, B, C, and V regions.
• the coated polycarbonate substrate was exposed to 1/3 such UV energy; whereas the coated PET substrate was exposed to 1/6 of such UV energy.
• Coatings of Low Refractive Index Formulations 1 and 2 were formed with a web coater onto the fully cured high refractive index layer on polycarbonate.
• Coatings of Low Refractive Index Formulations 3 and 4 were formed with the web coater onto the partially cured high refractive index layer on primed polyester. It is desired to have a first-order minimum in the reflection curve close to the design wavelength of 550 nm. In order to achieve this, the low index coating is targeted to have a dried thickness of 90-100 nm.
• the Low Index Refractive Index Formulations were syringe-pumped into a 4 inch wide coating die, and the coating was dried by passing through a 10 foot oven set at 120 0 C.
• the coatings were then cured with a Light Hammer 6 UV source (Fusion UV Systems, Inc., Gaithersburg, Maryland), at 100% power, under Nitrogen. Measurement of the UV output of the UV lamp resulted in the same energy and power readings for the UV A, B, C, and V regions as described above.
• the resulting cured Low Refractive Index layer was approximately 90 to 100 nanometers thick. Further details of the process conditions are included as follows.
• the four antireflective film samples were evaluated for % Haze, % Transmission, Contact Angle and Average % Reflection according to the test methods described above. The samples were then evaluated according to the Steel Wool Durability Test Method using a 1 kg weight after which their % Haze, Contact Angle and Average % Reflection were measured again. The results are recorded as follows.
• An antireflective film was prepared in a similar manner with Low Refractive Index Composition 1.
• Unprimed PET obtained from DuPont
• TM-AS-I This material is a dispersion of antimony tin oxide nanoparticles and a polyester binder in a mixed aqueous/organic solvent system, with total solids content determined to be 6.34 wt % by gravimetry.
• Coating formulations were prepared by dilution of the Sumicefine TM-AS-I with deionized water to 3.17 wt-% solids ("Primer 1") and 1.27 wt-% solids ("Primer 2").
• Primer 2 also contained 0.1 wt % of Tomadol 25-9 nonionic surfactant. Each of the formulations were coated on the PET and dried at 125°C to provide primer layers with nominal dry film thickness of 115 nm for Primer 1 and 40 nm for Primer 2. The high refractive index coating was then coated on the primer and the low refractive index layer applied to the high refractive index layer as previously described.
• the results show that the antistatic primer continues to provide antistatic properties even when a high refractive index layer and low refractive index layer are each coated over the antistatic primer.
• the antireflective film having Primer 1 and 2 were each evaluated according to the steel wool durability test and no scratches were observed after 300 wipes. Ink repellency after steel wool wear was nearly unchanged from before the test.

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• 2006
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