JP2007505359A - Durable optical element - Google Patents

Abstract

  The durable optical film (11) comprises a polymerized optical film structure having a microstructured surface and a scratch contrast ratio value in the range of 1.0 to 1.65 or 1.0 to 1.15. These durable optical films can include a plurality of nanoparticles and a round prism top microstructure.

Description

  The present invention relates generally to durable optical elements. More specifically, the present invention relates to a microstructure-containing article such as a brightness enhancement film, an optical illumination film, or a reflective element.

  Microstructured articles such as brightness enhancement films, light redirecting films, or reflective elements are made in a variety of forms. One such form includes a series of alternating tips and grooves. One example of such a form is a brightness enhancement film having a regular repeating pattern of symmetrical tips and grooves. Another example comprises a pattern in which the tip and groove are not symmetrical and the size, orientation, and distance between the tip and groove are not uniform.

  One drawback of current brightness enhancement films and optical lighting films is that the tips of the microstructures are susceptible to mechanical damage. For example, lightly rubbing with a fingernail or a hard, relatively sharp edge may cause the tip of the microstructure to break or break. During normal handling of brightness enhancement films, for example, in the manufacture of liquid crystal displays for laptop computers, conditions are encountered that are sufficient to break the tips of prior art microstructures.

  If the peak of the microstructure is destroyed, the reflectivity and refraction of the affected peak is reduced and substantially all transmitted light is scattered in the forward angular direction. Thus, when the brightness enhancement film is present in the display and the display is viewed vertically, the scratches in the brightness enhancement film have a lower brightness than the undamaged area around the film. However, when viewing the display at an angle near or greater than the “cut-off” angle, an angle at which the image on the display is no longer visible, the scratches are substantially greater than the undamaged area around the film. The brightness looks high. In any situation, scratches are highly undesirable in terms of aesthetic appearance, and a brightness enhancement film that is not limited to only a few secondary scratches is unacceptable for use in liquid crystal displays.

  Durability was a difficult property to quantify. Previously, microstructured articles were created by forming scratches on the microstructure surface and measuring either the width or depth of the scratch or the gain associated with the scratched microstructure surface. Durability measurements have been made. Previous durability tests have not necessarily provided reliable quantification or realistic interpretation of how scratches on the surface of microstructures look as optical display defects.

  In general, the present invention relates to durable optical elements useful in a variety of applications, such as optical elements such as microstructured films, and further to displays and other devices that incorporate the microstructured film. .

  In one embodiment, the durable optical film comprises a polymerized optical film structure having a microstructured surface and a scratch contrast ratio value in the range of 1.0 to 1.15.

  In other embodiments, the durable optical film has a microstructured surface comprising a plurality of round prism apexes extending along the first surface and a scratch contrast ratio in the range of 1.0 to 1.65. A polymerized optical film structure having a value.

  In a further embodiment, the durable optical film comprises a microstructured surface comprising a plurality of surface modified colloidal nanoparticles comprising silica, zirconia, or mixtures thereof and a scratch contrast in the range of 1.0 to 1.65. And a polymerized optical film structure having a specific value.

  The above summary of the present invention is not intended to describe each disclosed embodiment or every implementation of the present invention. These embodiments will be described more specifically with reference to the following drawings, detailed description, and examples.

  A more complete understanding of the present invention can be obtained when the following detailed description of the various embodiments according to the invention is examined in conjunction with the accompanying drawings.

  While the invention is susceptible to various modifications and alternative forms, specific examples thereof have been shown by way of example in the drawings. These specific examples will be described in detail. It should be understood, however, that the intention is not to limit the invention to the particular embodiments described. On the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.

  Durable articles according to the present invention can be used in various applications that require durable microstructured films, such as brightness enhancement films, light redirecting films, and displays and other devices that incorporate durable microstructures. It is thought that it is applicable to. While the present invention is not so limited, an evaluation of the various aspects of the present invention may be obtained by studying the examples provided below.

  The brightness enhancement film generally improves the on-axis brightness (referred to herein as “brightness”) of the lighting device. The brightness enhancement film can be a light transmissive microstructured film. The microstructured surface shape can be a plurality of prisms on the film surface that are adapted to redirect the light by reflection and refraction using the film. When used in optical displays such as those found in laptop computers, watches, etc., the microstructured optical film is a pair of light that is disposed at a desired angle from the normal axis that penetrates the optical display to escape light from the display. By limiting to the plane, it is possible to increase the brightness of the optical display. As a result, light that may be emitted from the display out of tolerance is reflected back into the display, where a portion thereof is “recycled” back to the microstructured film at an angle that can be dissipated from the display. Recycling is useful because it can reduce the power consumption required to provide a display with a desired level of brightness.

  A retroreflective film is generally capable of reflecting a significant percentage of incident light at a relatively large illumination angle, regardless of the rotational orientation of the sheet about an axis perpendicular to its major surface. The cube corner retroreflective film can comprise a body portion that typically has a substantially planar base surface and a structured surface that includes a plurality of cube corner elements opposite the base surface. Each cube corner element may include three substantially perpendicular optical surfaces that typically intersect at a single reference point or vertex. The bottom surface of the cube corner element acts as an aperture through which light passes when transmitted through the cube corner element. As described in US Pat. No. 5,898,523 (which is incorporated herein by reference), in use, light incident on the base surface of the sheet is reflected by the base surface of the sheet. , Refracted and transmitted through the corresponding bottom surface of the cube corner element disposed on the sheet, reflected from each of the three vertical cube corner optical surfaces, and redirected in the direction of the light source.

  For the terms defined below, these definitions shall be applied, unless a different definition is given in the claims or elsewhere in this specification.

  The term “polymer” refers to polymers, copolymers (eg, polymers formed using two or more different monomers), oligomers, and combinations thereof, as well as miscible blends by reactions such as coextrusion or transesterification. It is intended to include polymers, oligomers, or copolymers that can be formed in the state. Unless otherwise indicated, both block copolymers and random copolymers are included.

  The term “refractive index” is defined herein as the absolute refractive index of a material. This is, of course, the ratio of the speed of electromagnetic radiation in free space to the speed of the radiation in the material. The refractive index can be measured using a known method, and is generally measured using an Abbe refractometer in the visible light region.

  The term “colloid” is defined herein to mean particles (primary particles or associated primary particles) having a diameter of less than about 100 nm.

  As used herein, the term “associated particles” refers to a population of two or more primary particles that have aggregated and / or aggregated.

  As used herein, the term “aggregation” describes a strong association between primary particles that can be chemically bonded to each other. It is difficult to achieve degradation of the aggregates into smaller particles.

  As used herein, the term “aggregation” describes a weak association of primary particles that can be held together by charge or polarity and can be broken down into smaller components.

  The term “primary particle size” is defined herein as the size of unassociated single particles.

  The term “sol” is defined herein as a dispersion or suspension of colloidal particles in a liquid phase.

  The term “surface modified colloidal nanoparticles” refers to nanoparticles each having a modified surface such that the nanoparticles provide a stable dispersion.

  The term “stable dispersion” is used herein for a period of time, eg, about 24 hours, under ambient conditions, eg, at room temperature (about 20-22 ° C.), at atmospheric pressure, and extremely It is defined as a dispersion in which colloidal nanoparticles do not aggregate after standing under the condition of no electromagnetic force.

  The term “gain” is defined herein as a measure of brightness improvement of a display based on a brightness enhancement film and is a property of the optical material and is also a property of the geometry of the brightness enhancement film. Typically, the viewing angle decreases as the gain increases. Since improving the gain effectively increases the brightness of the backlight display, a high gain is desired for the brightness enhancement film.

  The description of a numerical range by endpoint includes all numerical values that fall within that range (eg 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4, and 5). Include).

  As used herein and in the appended claims, the singular forms “a”, “an”, and “the” include plural referents unless the content clearly differs. . 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” generally includes “and / or” in its sense, unless the content clearly differs. Is done.

  Unless otherwise indicated, all numbers representing the amounts of ingredients used in this specification and claims, measurements of properties such as contrast ratio, etc., are in each case referred to by the term “about”. Shall be qualified. Accordingly, unless indicated to the contrary, the numerical parameters set forth in the foregoing specification and appended claims will vary depending on the desired properties sought by those skilled in the art using the teachings of the present invention. It is an approximate value that can be. At the very least, it does not attempt to limit the application of the doctrine of equivalence to the claims, but each numeric parameter applies at least the usual rounding technique taking into account the number of significant digits reported. Must be interpreted. Although the numerical ranges and parameters representing the broad range of the present invention are approximate, the numerical values shown in the specific examples are reported as accurately as possible. Any numerical value, however, inherently contains certain errors necessarily resulting from the standard deviation found in their respective testing measurements.

  Durable microstructured articles such as prismatic optical films provide brightness enhancement functions by refraction and total internal reflection (TIR) by protruding prismatic structures. These structures are susceptible to damage from compression and breakage that causes some yield loss. Currently, cover sheets are often placed on top prism films to protect the prism surface from damage. The durability of the prism structure is an important attribute of the prism film, so it is highly desirable to be able to accurately measure this amount. Previous methods for measuring prism "scratch resistance" can detect differences between various prism films, but are sensitive enough to handle very slight scratches or compression. Absent. The methods and apparatus of the present invention presented herein provide increased sensitivity, and the results are in good agreement with the visibility of scratches on the backlight. Measurement methods and analysis techniques are described below and in the Examples section.

  Durable microstructured articles can be formed from a polymerizable composition. The polymerizable composition can be a substantially solvent-free radiation curable inorganic filled organic composite. The organic phase of the composition can consist of a reactive diluent, an oligomer and a crosslinkable monomer, optionally including a photoinitiator. The organic component can have a refractive index of at least 1.50 for most product applications and exhibits significant durability in its cured form. Lower refractive index compositions, i.e. compositions with a refractive index of less than 1.50, are generally more easily achieved based on a wide selection of commercially available materials within this refractive index range. Lower refractive index resins have utility in several applications that would be apparent to one skilled in the art. High transmittance in the visible light spectrum may be desired. Ideally, the composition minimizes the effects of any scratches that occur while at the same time optimizing the desired optical properties and is described in US Pat. No. 5,626,800. Retain significantly higher Tg (glass transition temperature) sufficient to avoid other brightness enhancement product failure modes such as

  The polymerizable composition may also contain inorganic oxide particles that are sized to avoid significant visible light scattering. The selected inorganic oxide particles can provide increased refractive index or scratch resistance, or both. It may be desirable to use a mixture of inorganic oxide particle types to optimize optical or material properties and reduce overall composition costs. The total composition of inorganic oxide particles, organic monomers and oligomers preferably has a refractive index greater than 1.49 or greater than 1.56. By using an inorganic oxide-filled polymer, it becomes possible to achieve durability that cannot be obtained with an unfilled resin alone. The cured composite composition satisfies all the product characteristics of durability, high visible light transmittance, optical transparency, high refractive index, environmental stability, and light stability, and at the same time has low viscosity, storage stability ( The composition must not chemically change over time, and the particles must not settle or phase separate), and preferably has an uncured composition requirement that is energy curable on a time scale of less than 5 minutes Moreover, the composition is substantially solvent-free. Compositions with high amounts of multifunctional monomers and reactive functionalized inorganic oxide particles retain the original master form as well as the existing brightness enhancement film form available from 3M Company (3M, Co.) To do.

  The durable article can include a polymeric structure having a plurality of surface modified colloidal nanoparticles. The durable article can be an optical element or optical product made from a base layer and an optical layer. The base layer and the optical layer can be formed from the same or different polymer materials. Polymeric structures having a plurality of surface-modified colloidal nanoparticles have the advantage that they can be formed in a solvent-free system.

  The surface-modified colloidal nanoparticles can be present in the polymerized structure in an amount effective to improve the durability and / or refractive index of the article or optical element. The surface-modified colloidal nanoparticles described herein have various desirable attributes, such as compatibility between the nanoparticles and the resin system such that the nanoparticles form a stable dispersion within the resin system. If the surface modification provides the reactivity between the nanoparticles and the resin system, the composite can be made more durable, and the appropriately surface modified nanoparticles Is added to the resin system, the influence on the viscosity of the uncured composition is reduced. If a combination of surface modifiers is used, the non-curability and curability of the composition can be manipulated. Properly surface-modified nanoparticles can improve the optical and physical properties of the optical element, for example, improve the mechanical strength of the resin and reduce the solid volume loading in the resin system. While increasing the viscosity, the change in viscosity is minimized, and the optical transparency is maintained while increasing the solid volume loading in the resin system. In some embodiments, in particular, the solventless system having the nanoparticle loading described herein has a viscosity in the range of 1-1000 cps at 85 degrees Celsius.

  The surface-modified colloidal nanoparticles can be oxide particles having a particle size greater than 1 nm and less than 100 nm or associated particle size. These measurements can be based on transmission electron microscopy (TEM). The nanoparticles can include metal oxides such as, for example, alumina, tin oxide, antimony oxide, silica, zirconia, titania, mixtures thereof, or mixed oxides thereof. The surface-modified colloidal nanoparticles can be substantially fully condensed or crystalline.

  Silica nanoparticles can have a particle size of 5-75 nm or 10-30 nm or 20 nm. Silica nanoparticles may be present in the durable article or optical element in an amount of 10-60 wt% or 10-40 wt%. Silica for use in the material of the present invention is commercially available from Nalco Chemical Co. (Naperville, Ill.) Under the product name NALCO COLLOIDAL SILICA. Has been. For example, silica includes NALCO products 1040, 1042, 1050, 1060, 2327, and 2329. Suitable fumed silicas include, for example, the trade names Aerosil series OX-50, -130, -150, available from DeGussa AG (Hanau, Germany), and- 200, and CAB-O-SPERSE 2095, CAB-O-SPERSE A105, CAB-O-SIL M5 available from Cabot Corp. (Tuscola, Ill.) Products that are present.

  The zirconia nanoparticles can have a particle size of 5-50 nm or 5-15 nm or 10 nm. Zirconia nanoparticles can be present in the durable article or optical element in an amount of 10-70 wt% or 30-55 wt%. Zirconia for use in the material of the present invention is commercially available from Nalco Chemical Co. (Naperville, Ill.) Under the product name NALCO OOSSOOO8.

  The titania, antimony oxide, alumina, tin oxide, and / or mixed metal oxide nanoparticles may have a particle size or associated particle size of 5-50 nm or 5-15 nm or 10 nm. The titania, antimony oxide, alumina, tin oxide, and / or mixed metal oxide nanoparticles may be present in the durable article or optical element in an amount of 10-70 wt% or 30-50 wt%. Mixed metal oxides for use in the materials according to the present invention are commercially available from Catalytics & Chemical Industries Corp. (Kawasaki, Japan) under the product name Optolake 3 Has been.

  The surface treatment of the nano-sized particles can provide a stable dispersion in the polymer resin. Preferably, the nanoparticles are stabilized by surface treatment so that the particles are well dispersed in the polymerizable resin to yield a substantially uniform composition. Furthermore, the nanoparticles can be modified by surface treatment at least a portion of their surface so that the stabilized particles can copolymerize or react with the polymerizable resin upon curing. In some embodiments, selection of a second surface modifier provides rheology modification (ie, increased or decreased viscosity) to have a corresponding lower viscosity and higher nanoparticle loading. Yes. In some embodiments, the second surface modifier is different from the first surface modifier.

  The nanoparticles can be treated with a surface treatment agent. Generally, the surface treatment agent imparts compatibility between the particle and the resin, and a first end that binds to the particle surface (covalently, by ionic bond, or through strong physisorption) and / or Or a second end that reacts with the resin when cured. Examples of surface treating agents include alcohols, amines, carboxylic acids, sulfonic acids, phosphonic acids, silanes, and titanates. The preferred type of treating agent is determined in part by the chemical nature of the metal oxide surface. Silanes are preferred for silica and others are preferred for siliceous fillers. For metal oxides such as zirconia, silanes and carboxylic acids are preferred. Surface modification can be performed either following mixing with the monomer or after mixing. In the case of silane, it is preferred to react the silane with the surface of the particles or nanoparticles prior to incorporation into the resin. The required amount of surface modifier depends on several factors such as particle size, particle type, modifier molecular weight, and modifier type. In general, it is preferred to bind a substantially monolayer modifier to the surface of the particles. The required binding procedure or reaction conditions also depend on the surface modifier used. In the case of silane, the surface treatment is preferably performed for about 1 to 24 hours at elevated temperature under acidic or basic conditions. Surface treatment agents such as carboxylic acids do not require elevated temperatures or long times.

  Representative embodiments of surface treating agents suitable for durable compositions include, for example, isooctyltrimethoxy-silane, N- (3-triethoxysilylpropyl) methoxyethoxyethoxyethylcarbamate (PEG3TES), Silquest ) A1230, N- (3-triethoxysilylpropyl) methoxyethoxyethoxyethylcarbamate (PEG2TES), 3- (methacryloyloxy) propyltrimethoxysilane, 3-acryloxypropyltrimethoxysilane, 3- (methacryloyloxy) propyltri Ethoxysilane, 3- (methacryloyloxy) propylmethyldimethoxysilane, 3- (acryloyloxypropyl) methyldimethoxysilane, 3- (methacryloyloxy) propyldimethyle Xysilane, 3- (methacryloyloxy) propyldimethylethoxysilane, vinyldimethylethoxysilane, phenyltrimethoxysilane, n-octyltrimethoxysilane, dodecyltrimethoxysilane, octadecyltrimethoxysilane, propyltrimethoxysilane, hexyltrimethoxysilane, Vinylmethyldiacetoxysilane, vinylmethyldiethoxysilane, vinyltriacetoxysilane, vinyltriethoxysilane, vinyltriisopropoxysilane, vinyltrimethoxysilane, vinyltriphenoxysilane, vinyltri-t-butoxysilane, vinyltris-isobutoxysilane , Vinyltriisopropenoxysilane, vinyltris (2-methoxyethoxy) silane, styrylethyltrimethoxysilane, merca Topropyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, acrylic acid, methacrylic acid, oleic acid, stearic acid, dodecanoic acid, 2- [2- (2-methoxyethoxy) ethoxy] acetic acid (MEEAA), beta -Compounds such as carboxyethyl acrylate, 2- (2-methoxyethoxy) acetic acid, methoxyphenylacetic acid, and mixtures thereof.

  Surface modification of the particles in the colloidal dispersion can be achieved in various ways. This method requires mixing of the inorganic dispersion and the surface modifier. Optionally, co-solvents such as 1-methoxy-2-propanol, ethanol, isopropanol, ethylene glycol, N, N-dimethylacetamide, and 1-methyl-2-pyrrolidinone may be added at this point. The co-solvent can improve the solubility of the surface modifier and also the surface modified particles. Subsequently, the mixture containing the inorganic sol and the surface modifier is reacted at room temperature or elevated temperature with or without mixing. In one method, the mixture can be reacted at about 85 ° C. for about 24 hours to produce a surface modified sol. In other methods where the metal oxide is surface modified, the surface treatment of the metal oxide may preferably include adsorption of acidic molecules onto the particle surface. The surface modification of the heavy metal oxide is preferably performed at room temperature.

Surface modification of ZrO ₂ with silane can be achieved under acidic or basic conditions. In some cases, the silane is heated for a suitable time under acidic conditions. The dispersion is then combined with aqueous ammonia (or other base). By this method, it is possible to remove the acid counter ion from the ZrO ₂ surface and to react with silane. In one method, the particles are precipitated from the dispersion and separated from the liquid phase.

  The surface modified particles can then be incorporated into the curable resin by various methods. In a preferred embodiment, a solvent exchange procedure is utilized. According to it, the resin is added to the surface-modified sol and the water and co-solvent (if used) are removed by evaporation, thus leaving the particles dispersed in the polymerizable resin. The evaporation step can be accomplished, for example, by distillation, rotary evaporation, or oven drying. If desired, the surface-modified particles can be extracted into a water-immiscible solvent prior to solvent exchange.

  As another option, other methods for incorporating surface-modified nanoparticles into the polymerizable resin are to dry the modified particles into a powder, followed by the addition of a resin material that disperses the particles. And including. The drying step of this method can be accomplished by conventional means suitable for the system, such as oven drying or spray drying.

  A combination of surface modifiers may be useful. In that case, at least one of the surface modifiers has a functional group that can be copolymerized with the curable resin. For example, the polymerizable group can be an ethylenically unsaturated functional group or a cyclic functional group that undergoes ring opening polymerization. The ethylenically unsaturated polymerizable group can be, for example, an acrylate group or a methacrylate group or a vinyl group. The cyclic functional group that undergoes ring-opening polymerization generally contains a heteroatom such as oxygen, sulfur, or nitrogen, and is preferably a three-membered ring containing oxygen such as an epoxide.

  The optical layer or microstructured layer can be formed from a wide variety of polymeric materials, including the partial list of polymeric materials described herein. This layer can be formed from monomers such as high refractive index materials, such as high refractive index (meth) acrylate monomers, halogenated monomers, and other such high refractive index monomers known in the art. For example, U.S. Pat. Nos. 4,568,445; 4,721,377; 4,812,032; and 5,424,339 (both Which is incorporated herein by reference). The thickness of the optical layer or microstructured layer can be in the range of about 10 to about 200 microns.

  Suitable polymeric resins for forming the optical layer or microstructured layer include acrylate monomer and / or methacrylate monomer u. v. A polymerization product is mentioned. Suitable resins are brominated alkyl substituted phenyl acrylates or methacrylates (e.g., 4) as described in US Pat. No. 6,355,754, which is hereby incorporated by reference. , 6-dibromo-2-sec-butylphenyl acrylate), methylstyrene monomer, brominated epoxy diacrylate, 2-phenoxyethyl acrylate, and hexafunctional aromatic urethane acrylate oligomer u. v. It is a polymerization product.

  Although most types of energy polymerizable telechelic monomers and oligomers are useful in the present invention, acrylates may be preferred because of their high reactivity. The polymerizable composition can be of a flowable viscosity that is low enough so that no bubbles are trapped in the composition and a complete microstructure geometry is obtained. Reactive diluents are typically SR-339, SR-256, SR-379, SR-395, SR-, available from Sartomer Co., Exton, Pa. Monofunctional or bifunctional monomers such as 440, SR-506, CD-611, SR-212, SR-230, SR-238, and SR-247. A reactive diluent having a refractive index greater than 1.50, such as SR-339, may be preferred. Also useful are oligomeric materials, particularly those having a high refractive index. The oligomeric material imparts bulk optical properties and durability to the cured composition. Exemplary useful oligomers and oligomer blends include CN-120, CN-104, CN-115, CN-116, CN- available from Sartomer Co., Exton, Pa. 117, CN-118, CN-119, CN-970A60, CN-972, CN-973A80, CN-975, and Ebecryl available from Surface Specialties, Smyrna, GA. ) 1608, 3200, 3201, 3302, 3605, 3700, 3701, 608, RDX-51027, 220, 9220, 4827, 4849, 6602, 6700-20T. It is. In addition, a multifunctional crosslinker can be used to achieve a durable high crosslink density composite matrix. Examples of multifunctional monomers include SR-295, SR-444, SR-351, SR-399, SR-355, available from Sartomer Co., Exton, Pa., Exton, Pa. SR-368, and PETA-K, PETIA, and TMPTA-N available from Surface Specialties, Smyrna, GA.

  The polyfunctional monomer can be used as a crosslinking agent to increase the glass transition temperature of the polymer resulting from the polymerization of the polymerizable composition. The glass transition temperature can be measured by methods known in the art such as differential scanning calorimetry (DSC), modulated DSC, or dynamic mechanical analysis. The polymeric composition is crosslinkable to a degree sufficient to provide a glass transition temperature of greater than 45 ° C.

  The monomer composition can have a melting point of less than about 50 ° C. The monomer composition can be a liquid at room temperature. The monomer composition can be polymerized by conventional free radical polymerization methods.

  Examples of initiators include organic peroxides, azo compounds, quinines, nitro compounds, acyl halides, hydrazones, mercapto compounds, pyrylium compounds, imidazoles, chlorotriazines, benzoins, benzoin alkyl ethers , Diketones, phenones and the like. Commercially available photoinitiators include DAROCUR 1173, DAROCUR 4265, IRGACURE 651, IRGACURE 1800, IRGACURE 369, IRGACURE 1700, and IRGACURE 1700. ) 907 and IRGACURE 819 include those commercially available from Ciba Geigy, but are not limited thereto. Phosphine oxide derivatives include LUCIRIN TPO, which is 2,4,6-trimethylbenzoyldiphenylphosphine oxide available from BASF, Charlotte, NC. The photoinitiator can be used at a concentration of about 0.1-10 weight percent or about 0.1-5 weight percent.

  The polymerizable compositions described herein may also contain one or more other useful ingredients that may be useful in such polymerizable compositions, as will be appreciated by those skilled in the art. For example, the polymerizable composition can include one or more surfactants, pigments, fillers, polymerization inhibitors, antioxidants, antistatic agents, and other available ingredients. Such ingredients may be included in amounts known to be effective. Surfactants such as fluorosurfactants can be included in the polymerizable composition to reduce surface tension, improve wettability, and result in smoother coatings and fewer coating defects.

The polymerizable composition can be formed from a hard resin. The term “hard resin” means that the resulting polymer exhibits an elongation at break of less than 50 or 40 or 30 or 20 or 10 or 5 percent when evaluated according to the ASTM D-882-91 procedure. Also, the hard resin polymer may exhibit a tensile modulus greater than 100 kpsi (6.89 × 10 ⁸ Pascal) when evaluated according to the ASTM D-882-91 procedure.

  The optical layer can be in direct contact with or optically aligned with the base layer and is of a size, shape, and thickness that can direct or focus the light flow by the optical layer sell. The optical layer can have a structured microstructured surface that can have any of several useful patterns as described below and shown in the figures and examples. The microstructured surface can be a plurality of parallel longitudinal edges extending along the length or width of the film. These ridges can be formed from a plurality of prism tops. These tops can be sharp, round, or flat or truncated. These include regular or irregular prismatic patterns and can be annular prismatic patterns, cube corner patterns, or any other lenticular microstructure. A useful microstructure is a regular prismatic pattern that can function as a total internal reflection film for use as a brightness enhancement film. Another useful microstructure is a corner cube prismatic pattern that can function as a retroreflective film or element for use as a reflective film. Another useful microstructure is a prismatic pattern that can function as an optical element for use in an optical display. Another useful microstructure is a prismatic pattern that can function as a light redirecting film or element for use in an optical display.

  The base layer can be of a property and composition suitable for use in an optical product (ie, a product designed to control the flow of light). As long as the material is sufficiently optically transparent and structurally strong enough to be assembled into or used in a specific optical product, almost any The material can be used as a base material. It is possible to select a base material that has sufficient temperature and aging resistance so that the performance of the optical product is not compromised over time.

  For any optical product, the specific chemical composition and thickness of the base material may depend on the requirements of the specific optical product being made. That is, the balance of requirements for strength, transparency, temperature resistance, surface energy, and adhesion to the optical layer is particularly balanced.

  Useful base materials include, for example, styrene-acrylonitrile, cellulose acetate butyrate, cellulose acetate propionate, cellulose triacetate, polyethersulfone, polymethyl methacrylate, polyurethane, polyester, polycarbonate, polyvinyl chloride, polystyrene, polyethylene naphthalate, Mention may be made of copolymers or blends based on naphthalenedicarboxylic acid, polycyclo-olefins, polyimides and glasses. Optionally, the base material can contain a mixture or combination of these materials. In one embodiment, the base can be multi-layered or contain a dispersed phase suspended or dispersed in a continuous phase.

  In some optical products such as microstructured products, such as brightness enhancement films, examples of preferred base materials include polyethylene terephthalate (PET) and polycarbonate. Examples of useful PET films include photographic grade polyethylene terephthalate and MELINEX® PET available from DuPont Films, Wilmington, Del.

  Some base materials may have optical activity and function as polarizing materials. Several bases (also referred to herein as films or substrates) are known in the optical arts to be useful as polarizing materials. Polarization of light by the film can be achieved, for example, by incorporating a dichroic polarizer in the film material that selectively absorbs the passing light. Light polarization can also be achieved by incorporating an inorganic material such as an aligned mica chip or by a discontinuous phase dispersed in a continuous film, such as droplets of light modulated liquid crystals dispersed in a continuous film. is there. As an alternative, films can be made from microfine layers of different materials. The polarizing material in the film can be aligned to the polarization orientation by utilizing methods such as stretching the film, applying an electric or magnetic field, and coating techniques, for example.

  Examples of polarizing films are described in US Pat. Nos. 5,825,543 and 5,783,120, both of which are hereby incorporated by reference. Things. The use of these polarizer films in combination with brightness enhancement films is described in US Pat. No. 6,111,696, which is hereby incorporated by reference.

  A second example of a polarizing film that can be used as a base is the film described in US Pat. No. 5,882,774 (also incorporated herein by reference). The commercially available film is a multilayer film sold under the trade name DBEF (dual brightness enhancement film) from 3M. The use of such multilayer polarizing optical films in brightness enhancement films is described in US Pat. No. 5,828,488, which is hereby incorporated by reference.

  This list of base materials is not exclusive and will be appreciated by those skilled in the art, but other polarizing and non-polarizing films may also be useful as a base for the optical product according to the present invention. . These base materials can be combined with any number of other films (eg, polarizing films, etc.) to form a multilayer structure. The final candidate list of additional base materials may include the films described in US Pat. Nos. 5,612,820 and 5,486,949, among others. The particular base thickness may also depend on the requirements described above imposed on the optical product.

  Durable microstructure-bearing articles can be made in a variety of forms, for example, having a series of alternating tips and grooves sufficient to make a total internal reflection film. An example of such a film is a brightness enhancement film having a regular repeating pattern of symmetrical tips and grooves, while other examples have patterns where the tips and grooves are not symmetrical. Examples of microstructured articles useful as brightness enhancement films are disclosed in US Pat. Nos. 5,175,030 and 5,183,597, both of which are incorporated herein by reference. )).

  According to these patents, the microstructure-bearing article comprises: (a) preparing a polymerizable composition; and (b) a master negative microstructured molded surface in a barely sufficient amount to fill the master cavity. Depositing the polymerizable composition thereon; (c) moving the cavity between the preformed base and the master (at least one of which is flexible) by moving the bead of the polymerizable composition; And (d) a step of curing the composition. The master can be a metal article such as nickel, nickel-plated copper, or brass, or can be a thermoplastic material that is stable under polymerization conditions and preferably has a surface energy that can cleanly remove the polymerized material from the master. . A specific method used to construct the microstructure surface features described herein is described in US Pat. No. 5,691,846, which is hereby incorporated by reference. It may be similar to the described molding method. Microstructure articles according to the present invention can be formed from a continuous process at any desired length, for example, such as 5, 10, 100, 1000 meters or more.

  Durable articles can be used in applications that require durable microstructured films such as brightness enhancement films. These durable brightness enhancement film structures are, for example, US Pat. No. 5,771,328, US Pat. No. 5,917,664, US Pat. No. 5,919,551, A wide variety of microstructures as found in US Pat. No. 6,280,063 and US Pat. No. 6,356,391, both of which are hereby incorporated by reference. May include a modified film.

  A backlight type liquid crystal display generally indicated by 10 in FIG. 1 includes a brightness enhancement film 11 according to the present invention that can be positioned between a diffuser 12 and a liquid crystal display panel 14. The back-lit liquid crystal display also reflects light in the direction of the liquid crystal display panel, as well as a light source 16 such as a fluorescent lamp, an optical waveguide 18 for transmitting light to reflect in the direction of the liquid crystal display panel And a white reflector 20 for making it. The brightness enhancement film 11 increases the brightness of the liquid crystal display panel 14 by collimating the light emitted from the optical waveguide 18. Increasing the brightness makes it possible to sharpen the image generated by the liquid crystal display panel and reduce the power of the light source 16 to generate the selected brightness. The brightness enhancement film 11 in the backlight type liquid crystal display is a computer display (laptop display and computer monitor), a television, a video recorder, a mobile communication device, a handheld device (ie, a mobile phone, a PDA), an automobile and an avionic Useful for devices such as equipment displays (represented by reference characters 21). Although FIG. 1 shows an edge light type system, it will be appreciated that the illumination system can directly illuminate the film 11 for use in a transmissive LCD television.

  The brightness enhancement film 11 includes an array of prisms represented by prisms 22, 24, 26, and 28 as shown in FIG. Each prism, such as the prism 22, has a first surface 30 and a second surface 32. The prisms 22, 24, 26, and 28 include a first surface 36 on which the prism is formed, and a second surface 38 that is substantially flat or planar and opposite the first surface. It can be formed on the body portion 34 having the same.

  A linear array of honest prisms can provide both optical performance and ease of manufacture. By right prism is meant that the apex angle θ is approximately 90 ° but may be in the range of about 70 ° to 120 ° or about 80 ° to 100 °. The prism surfaces need not be the same, and the prisms may be inclined with respect to each other. Furthermore, the relationship between film thickness 40 and prism height 42 is not critical, but it is desirable to use thinner films with well-defined prism surfaces. If the surface is projected, the angle that the surface can make with the surface 38 may be 45 °. However, this angle will vary depending on the pitch of the surface or the top angle θ.

  3-9 illustrate exemplary embodiments of the construction of the optical element. It should be noted that these drawings are not to scale, and in particular, the size of the structured surface is exaggerated considerably for illustrative purposes. The structure of the optical element may include a combination of the embodiments described below, that is, two or more.

  With reference to FIG. This figure illustrates a representative cross-sectional view of a portion of one embodiment of an optical element or light directing film. Film 130 includes a first surface 132 and an opposing structured surface 134 that includes a plurality of substantially linearly extending prism elements 136. Each prism element 136 has a first side surface 138 and a second side surface 138 ′, the upper edges of which intersect to define the peak or top 142 of the prism element 136. The bottom edges of the side surfaces 138, 138 'of adjacent prism elements 136 intersect to form a groove 144 that extends linearly between the prism elements. In the embodiment illustrated in FIG. 3, the dihedral angle defined by the prism apex 142 is approximately 90 degrees, but the exact magnitude of the dihedral angle in this and other embodiments is desired. It will be understood that it can be varied according to the optical parameters.

  The structured surface 134 of the film 130 can be described as a plurality of alternating zones of prism elements having peaks spaced at different distances from a common reference plane. The common reference plane is optional. One convenient example of a common reference plane is a plane containing the first surface 132; another example is a plane defined by the bottom edge of the lowest groove of the structured surface indicated by dashed line 139. . In the embodiment illustrated in FIG. 3, the lower prism elements are about 50 microns wide and about 25 microns high (measured from dashed line 139), while the higher prism elements are about 50 microns wide. And about 26 microns in height. The width of the zone containing the higher prism elements can be as large as about 1 micron to 300 microns. The width of the zone containing the lower prism elements is not critical and can be as large as 200 microns to 4000 microns. In any given embodiment, the zone of the lower prism element may be at least as wide as the zone of the higher prism element. Those skilled in the art will appreciate that the article shown in FIG. 3 is merely illustrative and is not intended to limit the scope of the present invention. For example, the height or width of the prism element can be varied within practical limits. That is, it is practically possible to machine an accurate prism within a range from about 1 micron to about 200 microns. In addition, the dihedral angle can be changed, or the prism axis can be tilted to achieve a desired optical effect.

  The width of the first zone can be less than about 200-300 microns. Under normal viewing conditions, it is difficult for the human eye to identify small changes in light intensity that occur in regions of width less than about 200-300 microns. Thus, if the width of the first zone is less than about 200-300 microns, any optical coupling that can occur in this zone cannot be detected by the human eye under normal viewing conditions.

  The height of one or more prism elements is varied along its linear region to construct alternating zones that include portions of the prism elements having peaks arranged at various heights on a common reference plane. It is also possible to realize a variable height structured surface.

  FIG. 4 shows another embodiment of an optical element similar to that in FIG. However, the film 150 includes a structured surface 152 having zones of relatively low prism elements 154 separated by zones containing a single higher prism element 156. In much the same way as the embodiment shown in FIG. 3, the higher prismatic elements limit the physical access of the second sheet of film to the structured surface 152, thereby allowing a visible wet-out condition. Reduce the performance. The human eye is sensitive to changes in the height of the surface in the light directing film, and it has been determined that a relatively wide zone of higher prism elements appears as visible lines on the surface of the film. While this does not substantially affect the optical performance of the film, the line may be undesirable in certain commercial situations. As the zone width of the higher prism elements is reduced, the human eye's ability to detect film lines caused by the higher prism elements is correspondingly reduced.

  FIG. 5 is a representative example of another embodiment of the optical element. In this case, the prism elements have substantially the same size, but are arranged in a repetitive staircase pattern, that is, a lamp pattern. The film 160 shown in FIG. 5 includes a first surface 162 and an opposing structured surface 164 that includes a plurality of substantially linear prism elements 166. Each prism element has opposing side surfaces 168, 168 ′ that intersect at their upper edges to define a prism peak 170. The dihedral angle defined by the opposing side surfaces 168, 168 'is approximately 90 degrees. In this embodiment, the highest prism can be considered as the first zone and the adjacent prism can be considered as the second zone. Again, the first zone can be less than about 200-300 microns.

  FIG. 6 shows a further embodiment of the optical element. The film 180 disclosed in FIG. 6 includes a first surface 182 and an opposing structured surface 184. This film can be characterized in that the second zone containing relatively low prism elements contains prism elements of various heights. The structured surface shown in FIG. 6 has the further advantage of substantially reducing the visibility of the human eye to lines on the film surface caused by changes in prism element height.

  FIG. 7 shows another embodiment of an optical element for providing a soft cutoff. FIG. 7 shows a brightness enhancement film according to the present invention, indicated generally at 240. The brightness enhancement film 240 includes a substrate 242 and a structured surface material 244. The substrate 242 can generally be a polyester material. The structured surface material 244 can also be an ultraviolet curable acrylic material or other polymeric material as discussed herein. The outer surface of the substrate 242 is preferably flat, but can have a structure. In addition, other alternative substrates can be used.

  Structured surface material 244 has a plurality of prisms such as prisms 246, 248, and 250 formed thereon. Prisms 246, 248, and 250 have peaks 252, 254, and 256, respectively. Peaks 252, 254, and 256 all preferably have a peak or prism angle of 90 degrees, but include angles in the range of 60 degrees to 120 degrees. A valley 258 exists between the prisms 246 and 248. A valley 260 exists between the prisms 248 and 250. Valley 258 can also be considered to have a valley associated with prism 246, has a valley angle of 70 degrees, and valley 260 can be considered a valley associated with prism 248. , With a valley angle of 110 degrees, but other values can be used. Effectively, the brightness enhancement film 240 increases the apparent on-axis brightness of the backlight by reflecting and recycling a portion of the light and refracting the remaining portion, like prior art brightness enhancement films. The prisms are tilted in alternating directions. The effect of tilting the prism is to increase the size of the output light cone.

  FIG. 8 shows another embodiment of an optical element having a round prism top. The brightness enhancement article 330 is characterized by a flexible base layer 332 having a pair of opposing surfaces 334, 336, both of which are integrally formed with the base layer 332. The surface 334 is characterized by a series of protruding light diffusing elements 338. These elements can take the form of “ridges” in the surface made of the same material as layer 332. Surface 336 is characterized by an array of linear prisms having a blunt or round peak 340 integrally formed with base layer 332. These peaks are characterized by a chord width 342, a cross-sectional pitch width 344, a radius of curvature 346, and a root angle 348. In this case, the chord width is equal to about 20-40% of the cross-sectional pitch width, and the radius of curvature is equal to about 20-50% of the cross-sectional pitch width. The root angle is in the range of about 70-110 degrees or about 85-95 degrees, with a root angle of about 90 degrees being preferred. The arrangement of prisms in the array is selected to maximize the desired optical performance.

  Round prism top brightness enhancement articles usually have the problem of reduced gain. However, the addition of high refractive index surface modified colloidal nanoparticles can offset the gain loss of the round prism top brightness enhancement article.

  FIG. 9 shows another embodiment of an optical element having a flat or planar prism top. The brightness enhancement article 430 is characterized by a flexible base layer 432 having a pair of opposing surfaces 434, 436, both of which are integrally formed with the base layer 432. The surface 434 is characterized by a series of protruding light diffusing elements 438. These elements may take the form of “flat ridges” in the surface made of the same material as layer 432. The surface 436 is characterized by an array of linear prisms having flat peaks or planar peaks 440 that are integrally formed with the base layer 432. These peaks are characterized by a planarization width 442 and a cross-sectional pitch width 444. In this case, the planarization width can be equal to about 0-30% of the cross-sectional pitch width.

  Another method of extracting light from the optical waveguide is to use leaky total internal reflection (TIR). In one type of leakage TIR, the optical waveguide has a wedge shape, and the light incident on the thick edge of the optical waveguide is totally internally reflected until a critical angle is achieved with respect to the top and bottom surfaces of the optical waveguide. These subcritical angle rays are then extracted at a viewing angle with respect to the output surface. That is, in a more concise manner, the light is refracted from the optical waveguide. These rays must then be redirected to be substantially parallel to the viewing or output axis of the display device in order to be useful for illuminating the display device. This direction change is usually achieved using a direction change lens or a direction change film.

  10-12 illustrate an illumination device comprising a direction change film. The redirecting film may include the material according to the present invention disclosed herein to form a durable redirecting film. The redirecting lens or redirecting film typically comprises a prism structure formed on the input surface, the input surface being disposed adjacent to the optical waveguide. Light rays emitted from the optical waveguide with a viewing angle of typically less than 30 degrees with respect to the output surface strike the prism structure. The light rays are refracted at the first surface of the prism structure and reflected at the second surface of the prism structure, so that in a desired direction, for example, in a direction substantially parallel to the viewing axis of the display, Directed by a redirecting lens or film.

  FIG. 10 will be described. The illumination system 510 includes an optically coupled light source 512; a light source reflector 514; an optical waveguide 516 having an output surface 518, a back surface 520, an input surface 521, and an end surface 522; a reflector 524 adjacent to the back surface 520. A first light redirecting element 526 having an input surface 528 and an output surface 530; a second light redirecting element 532; and a reflective polarizer 534. The optical waveguide 516 may be wedge-shaped or modified. As is well known, the purpose of the light guide is to distribute light from the light source 512 uniformly over a much larger area than the light source 512, and more particularly over substantially the entire area formed by the output surface 518. That is. The optical waveguide 516 further preferably accomplishes these tasks in a compact thin package.

  The light source 512 may be a CCFL edge coupled to the input surface 521 of the light guide 516, and the lamp reflector 514 may be a reflective film that encloses the light source 512 to form a lamp cavity. The reflector 524 supports the light guide 516 and may be an efficient back reflector such as a uniform diffuse film or a specular reflection film or a combination thereof.

  Edge coupled light is confined by TIR and propagates from the input surface 521 toward the end surface 522. Light is extracted from the optical waveguide 516 due to TIR leakage. Each time the light beam confined in the optical waveguide 516 is bounced back by TIR, the incident angle with respect to the plane of the upper end wall and the lower end wall increases based on the wedge angle. Thus, light eventually refracts out of each of the output surface 518 and the back surface 520 because it cannot be confined by TIR. The light that is refracted from the back surface 520 is returned to the direction of the optical waveguide 516 by either regular reflection or diffuse reflection by the reflector 524, and most of the light passes through it. The first light redirecting element 526 is arranged to redirect the light emitted from the output surface 518 along a direction substantially parallel to the preferred viewing direction. The preferred viewing direction may be perpendicular to the output surface 518, but more typically will make an angle with the output surface 518.

  As shown in FIG. 11, the first light redirecting element 526 has an output surface 530 that is substantially planar and an input surface 528 formed by an array 536 of prisms 538, 540, and 542. It is a light transmissive optical film. The second light redirecting element 532 may also be a light transmissive film, such as the Minnesota Mining and Manufacturing Company, St. Paul, Minnesota. Brightness enhancement films such as the 3M Brightness Enhancement Film product (sold as BEFIII) available from Paul, Minn). The reflective polarizer 534 may be an inorganic polymer cholesteric liquid crystal reflective polarizer or film. Suitable films are 3M Diffuse Reflective Polarizer (3M Diffuse Reflective Polarizer) film products (sold as DRPF) or Specular Reflective Polarizer (S specular Reflective PolarE F film products) Both of which are available from the Minnesota Mining and Manufacturing Company.

  Within array 536, each prism 538, 540, and 542 can be formed with a different side angle with respect to its corresponding adjacent prism. That is, prism 540 can be formed with prisms 538 (angles A and B) and side angles (angles C and D) different from prism 542 (angles E and F). As shown, prism 538 has a prism angle or groove angle equal to the sum of angles A and B. Similarly, prism 540 has a prism angle equal to the sum of angles C and D, while prism 542 has a prism angle equal to the sum of angles E and F. Although array 536 is shown to include three different prism structures based on different prism angles, it will be appreciated that virtually any number of different prisms can be used.

は、プリズム５３８について図１１に示されている。プリズム軸

は、プリズム５３８について示されるように、出力表面５３０に対して法線方向に配置してもよいし、またはプリズム５４０および５４２についてそれぞれ仮想軸

により例示されるように、光源に向かう方向もしくは光源から離れる方向のいずれかで出力表面に対して角度をなして配置してもよい。 Prisms 538, 540, and 542 can also be formed using a common prism angle but various prism orientations. Prism axis

Is shown in FIG. 11 for prism 538. Prism axis

May be positioned normal to the output surface 530, as shown for prism 538, or an imaginary axis for prisms 540 and 542, respectively.

May be arranged at an angle to the output surface either in the direction towards the light source or in the direction away from the light source.

  The prisms 538, 540, and 542 can be arranged in the array 536 in a regular repeating pattern or cluster 543 of prisms as shown in FIG. 11, and the array 536 has similar prisms adjacent to similar prisms. Although not shown as such, it is also possible to use such a form. Further, within array 536, prisms 538, 540, and 542 are successively connected from a first prism configuration such as prism configuration 538 to a second prism configuration such as prism configuration 540 and further to the next configuration. It is also possible to change it. For example, the prism form can be changed stepwise from the first prism form to the second prism form. As another option, it is also possible to change the prism for each step as in the shape shown in FIG. Within each cluster 543, the prisms have a prism pitch selected to be less than the spatial ripple frequency. Similarly, the clusters can have a regular cluster pitch. The prism array can be symmetric as shown in FIG. 11, or the prism array can be asymmetric.

  Although the array 536 shown in FIG. 11 has symmetrical prisms, it is also possible to use an array of prisms such as the array 536 ′ shown in FIG. 12 formed in the light redirecting element 526 ′. . Next, FIG. 12 will be described. In array 536 ', for example, prism 538' has an angle A 'that is not equal to angle B'. Similarly for prisms 540 ′ and 542 ′, angle C ′ is not equal to angle A ′ and angle D ′, and angle E ′ is not equal to any of angle A ′, angle C ′, or angle F ′. . The array 536 'can advantageously be configured to tilt the tool each time it is cut using a single diamond cutting tool at a predetermined angle to produce prisms of different prism angles and symmetry. However, it will be appreciated that when a single cutting tool is used, the prism angles are the same (ie, A + B = C + D = E + F).

  Although it is believed that as few as two different prism configurations can be used to be arranged in a cluster in array 536, as many prism sizes as needed to achieve modification of the output profile from light guide 516 are achieved. May be used. One purpose of the prism side angle change is to disperse the optical power so that various amounts of optical power enter the first light redirecting element 526. Various shaped prisms 538, 540, and 542 serve to provide substantially uniform sampling from the input aperture of the light guide, thereby minimizing the non-uniformity of the light extracted from the light guide 516. Limit to the limit. The net result is that the ripple effect, particularly near the entrance end 521 of the optical waveguide 516, is effectively minimized.

  FIG. 13 is a schematic flow diagram illustrating a method 600 for determining a scratch contrast ratio. The method generally includes providing 610 a microstructured article, forming a scratch 620 in the microstructured article, irradiating the scratched optical film 630, Measuring a plurality of scratch contrast ratios 640 and then determining a maximum scratch contrast ratio 650.

  The microstructured article can be any microstructured article described herein. Scratch formation 620 can be accomplished by any number of means. In general, scratches are formed using a consistent set of parameters to assess the durability of the microstructured article. One exemplary parameter set used to form a scratch includes the use of a probe tip with a radius of 0.002 mm. The probe tip can be pulled across the microstructured surface in a direction perpendicular to the prism groove direction at 10 fpm under a fixed load of 50 g. As the speed, probe design, or probe weight changes, scratches of different width and depth will be formed and the optical detection results will change. Thus, the only requirement for creating scratches is to use a consistent parameter set for each scratch formation to assess the durability of the microstructured article.

  The scratched optical film can be irradiated 630 with an arbitrary number of light sources (for example, a backlight). The light source can be a diffuse light source that provides substantially uniform diffused light. A detector, such as a camera, can capture 640 an optical image of the scratched microstructure surface and measure the scratch contrast ratio along the length of the scratch. The detector and / or scratched film can be rotated so that the detector is off-axis relative to the scratched film to obtain a maximum contrast ratio. Next, the contrast ratio data is manipulated (ie, integrated, normalized, etc.) to determine the maximum contrast ratio of the scratched film based on the contrast ratio data provided by the detector 650. Is possible.

  After obtaining an image of the scratch sample, the data can be exported as an array of luminance values. One simple and straightforward way to calculate the optical contrast of the scratch is to extract a luminance line profile across each scratch. For some measurements, there is sufficient noise in the data, but as a result, in any given line profile, the brightness spike based on very few scratches may be below the random noise characteristic. Therefore, it may be necessary to apply some noise reduction scheme to the data, ideally a scheme that significantly reduces noise based on localized point defects without attenuating the intensity spike of the scratch. . This can be achieved by using a one-dimensional averaging method.

  Since the scratch is a one-dimensional characteristic, the brightness peak of the scratch is not reduced even if averaged along the direction of the scratch. However, this method effectively attenuates any two-dimensional characteristic. This is because they have a very limited range along the average direction. This type of average increases sensitivity to spatially extended properties with very low contrast, but is easily detected by human image processing mechanisms.

  In order to generate actual data by a one-dimensional average, it is important that the average direction is the same direction as the scratches. Otherwise, the scratch peak brightness is attenuated by being more widely spread across the brightness profile. If the sample contains several scratches that are not at the same angle, it is not possible to obtain a precisely averaged luminance peak value for each individual scratch using only one average direction. Therefore, the averaging algorithm is executed with a plurality of one-dimensional average paths along different directions and records the profile obtained for each. The highest scratch contrast ratio value calculated for each scratch is then recorded. By performing a one-dimensional average along a plurality of directions and recording the peak contrast ratio for each scratch, an appropriate value can be reliably obtained for each scratch regardless of the orientation. The contrast ratio value calculated by the algorithm is plotted along with the composite optimal 1D average profile. If the background is noisy, the algorithm plots both the CR value and the composite luminance profile because some spikes or bumps may be identified in the data as scratches even if not scratches It is useful. By examining composite profiles, it is very easy to determine which calculated contrast ratio values are from actual scratches and which are from other profile artifacts. .

  One embodiment of a durable optical film comprises a microstructured surface and a range of 1.0 to 1.15 or 1.0 to 1.12 or 1.0 to 1.10 or 1.0 to 1.05 And a polymerized optical film structure having a scratch contrast ratio. The optical film can be formed from any of the materials described herein. The optical film can include a plurality of surface-modified colloidal nanoparticles composed of silica, zirconia, or mixtures thereof, as described herein. The optical film can have any microstructure described herein. In one exemplary embodiment, the microstructure includes a plurality of ridges extending along the first surface. These ridges can be rounded with a radius in the range of 4-7 micrometers.

  Other embodiments of the durable optical film include a microstructured surface that includes a plurality of round prism peaks extending along the first surface, and 1.0 to 1.65 or 1.0 to 1.4. Or a polymerized optical film structure having a scratch contrast ratio value in the range of 1.0 to 1.10. The optical film can include a plurality of surface-modified colloidal nanoparticles composed of silica, zirconia, or mixtures thereof, as described herein. The optical film can have any microstructure described herein. In one exemplary embodiment, the microstructure includes a plurality of ridges extending along the first surface. These ridges can be rounded with a radius in the range of 4-7 micrometers.

  In other exemplary embodiments, the durable optical film has a microstructured surface comprising a plurality of surface-modified colloidal nanoparticles of silica, zirconia, or mixtures thereof, and 1.0 to 1.65 or 1 A polymerized optical film structure having a scratch contrast ratio value in the range of 0.0 to 1.4 or 1.0 to 1.10. As described herein, nanoparticles, such as silica, can have a particle size of 5 to 75 nanometers as desired. The durable optical film may contain nanoparticles such as silica at 10-60% by weight of the microstructured surface. The optical film can have any microstructure described herein. In one exemplary embodiment, the microstructure includes a plurality of ridges extending along the first surface. These ridges can be rounded with a radius in the range of 4-7 micrometers.

  FIG. 14 is a schematic diagram of an exemplary apparatus 700 for determining a scratch contrast ratio. The apparatus 700 generally includes a light source or backlight 710, a polymerized optical film structure having a microstructured surface and a scratch on the microstructured surface 720 disposed on the backlight 710, and a scratch. And a detector 730 configured to acquire image data from the wound. The detector 730 is disposed on the optical film 720 and the computer 740 is configured to manipulate the image data for the scratched optical film 720 to calculate the maximum contrast ratio.

  The light source 710 may be a diffuse light source or a substantially uniform diffuse light source, for example, a Teflon light box. The detector 730 can be any device that can capture an optical image of a scratched microstructured surface and provide the optical image as data to a data manipulation computer 740. The detector 730 can be placed at any useful distance, such as 5-40 cm or 10-20 cm, from the scratched microstructure surface.

  The optical film 720 has an axis aa that is orthogonal to the microstructured surface of the optical film 720. The detector 730 can capture image data with an arbitrary angle θ off-axis. In some embodiments, the scratch is most visible or detectable from the off-axis angle. This angle can be 1 to 89 degrees, or 20 to 70 degrees, 35 to 60 degrees, or 40 to 50 degrees. Detector 730 and / or light source 720 (with associated platform) can be rotated or moved to achieve angle θ.

  The present invention is not to be considered limited to the particular embodiments described herein, but encompasses all embodiments of the present invention that are fairly set forth in the appended claims. You must understand that there is. Various modifications, equivalent methods, and numerous configurations to which the present invention can be applied will become apparent to those skilled in the art to which the present invention pertains upon examination of this specification.

Fabrication of Optical Elements Compositions used in the fabrication of exemplary optical elements according to the present invention are described in the examples shown below. The scratch contrast ratio of the optical element is shown in Table 1 shown below. Exemplary optical elements containing prismatic microstructures are described in U.S. Pat. Nos. 5,175,030 and 5,183,597 or filed May 12, 2003. Similar to those described in US patent application Ser. No. 10/436377 assigned to the same assignee and US patent application Ser. No. 10 / 662,085 filed on Sep. 12, 2003. It was. These patents are hereby incorporated by reference.

  Unless otherwise specified, microprism-like structures have a 90 ° apex angle defined by the side slope of the prism, and the average distance between adjacent apexes is about 50 micrometers. The prism apex or apex has a round shape with a radius of 7 microns.

  All percentages given in the examples are percentages by weight unless otherwise specified.

Scratch Contrast Ratio (CR) Test Method Scratch Formation This test method describes a procedure for scratching various prism structures. This test is considered a destructive test. The following materials and equipment are generally commercially available unless otherwise specified.
・ ANORAD Intelligent Axis Control System (Anorad, Shirley, NY)
・ VIA controller ・ Sony monitor ・ 50 gram weight ・ 5.5 inch x 7 inch prism film sample (samples can be of various sizes)
・ Scotch Magic Tape 810 (Scotch Magic Tape 810)
・ 9-inch x 9-inch TX309 wipe (TX309 Wipe)
• 3 "x 3" Plexiglas sample holder with black border and matte finish.
• 6.5 inch × 4 inch Plexiglas alignment frame • Ethanol • Diamond needle process conditions are a probe tip with a radius of 0.002 mm with a bevel angle of 160 degrees. The probe tip will be pulled across the sample prism film perpendicular to the prism groove direction or ridge length at a speed of 10 feet per minute under a fixed load of 50 grams.

  The prism film sample is placed in a Plexiglas sample holder so that the grooves are placed perpendicular to the direction of needle movement and secured with a Scotch Magic Tape 810. The sample holder is then placed in the alignment frame and then placed on the stage to form a scratch. Level the probe holder. Attach a 50 gram weight to the needle and place the diamond needle in the probe holder. Run the software of ANORAD Intelligent Axis Control System and enter the control speed (10 ft / min) and the length of scratch (0.25 inch). A first scratch is created by the ANORAD system. Next, wipe the probe tip with ethanol. Move the Plexiglas holder containing the scratched sample to the next position to scratch. Proceed as described above to form another 1/8 inch scratch from the first scratch to form a scratched sample with two scratch lines. Repeat these steps for each sample.

Optical Scratch Measurement This test method describes an optical measurement procedure for evaluating a scratch formed on a prism film with a needle. The following materials and equipment are generally commercially available unless otherwise specified.
-Optical table-Incandescent light source with regulator box (Dolan-Jenner Industries Fiber-Light Model No. 180 (Fiber-Lite Model No. 180)) (0.5 inch thick) 6 inch x 6 inch Teflon cube box light source) —Set power setting to highest (10).
ESP-300 motion controller (Newport Industries)
ESP-300 utility software (Newport Industries)
-Stages and tables for angle measurement (Newport Industries)
-Radiant Imaging camera (Prometric CCD)
-Radiant Imaging software 8.0 (Radient Imaging Co.)
• Round mirror • Dot pattern scale gauge • Plexiglas sample holder Teflon cubes are attached to a goniometer and secured to an optical table. The distance between the Teflon cube light source and the camera lens is 6.25 inches. The Plexiglas sample holder already described above is placed on a Teflon cube box. Attach a round mirror to the sample holder and activate the light source. A sigma 105 mm lens is placed in a Prometrics camera, and the f value is set to f22. Activate the ESP-300 motion controller and launch the ESP-300 utility software.

  Align the mirror on the backlight with the camera lens. With the Radiant Imaging software 8.0 running, set the camera to focus mode and capture the mirror image. The X or Y axis of the goniometer is advanced using RI 8.0 software so that the mirror faces the center of the lens. This will cause the sample to face the center of the lens with a goniometer angle range of 35 to 55 degrees. After this is achieved, remove the mirror from the cube box and replace it with a dot pattern scale gauge. By using the crop technique, a series of dot patterns arranged in stages on the scale is selected. The camera lens is focused so that the dot pattern is clear and clear. Any distortion will provide inconsistent data. Using ESP software, set all the values displayed in the controller position window box to zero. Select the jog characteristic in the position box window and enter a value of 40.000. This will move the goniometer stage to an off-axis angle of 40 degrees. Replace the dot pattern scale gauge with the sample to be analyzed. Select the camera calibration characteristics in the Radiant Imaging software and reflect them in the automatic calibration. Calibration should be done at the end of every 5 measurements. Using Radiant software, select the crop characteristics of the software program and crop the scratch line.

  Click the measurement start tab to capture the image. The images will be stored in a Radiant software database. After the image is stored in the database, the goniometer stage is rotated by entering a value of 1.000 in the position box and another image is captured. The goniometer stage continues to rotate until an image is acquired in an angle range of 40 to 50 degrees in 1 degree increments. Repeat these steps for additional samples.

  By converting the file as a luminance type file, the data file of each image captured in the Radiant software database is exported, and the luminance file is exported for each image for further data processing.

Determination of Scratch Contrast Ratio After acquiring an image of a scratch sample, the data can be exported as an array of luminance values. One simple and straightforward way to calculate the optical contrast of the scratch is to extract a luminance line profile across each scratch. For some measurements, there is sufficient noise in the data, but as a result, in any given line profile, the brightness spike based on very few scratches may be below the random noise characteristic. Thus, it may be necessary to apply some noise reduction scheme to the data, ideally a scheme that significantly reduces noise based on localized point defects without attenuating the intensity spike of the scratch. . This can be achieved by using a one-dimensional averaging method.

  Contrast ratio (CR) refers to a measure of the visibility of scratches on a prism film on a backlight source. Scratches can be more easily identified by the off-axis angle. Contrast ratio is a measure of the brightness of light emitted from a scratched area as compared to the background, i.e., the non-scratched area. A contrast ratio of 1.00 is invisible to the human eye. The larger the contrast ratio value, the easier it is to visually detect the scratch. Since the contrast ratio value can vary as a function of viewing angle, the maximum contrast ratio value across all angles is selected as the contrast ratio for each sample.

  Since the scratch is a one-dimensional characteristic, the brightness peak of the scratch is not reduced even if averaged along the direction of the scratch. However, this method effectively attenuates any two-dimensional characteristic. This is because they have a very limited range along the average direction. This type of average increases sensitivity to spatially extended properties with very low contrast, but is easily detected by human image processing mechanisms.

  In order to generate actual data by a one-dimensional average, it is important that the average direction is the same direction as the scratches. Otherwise, the scratch peak brightness is attenuated by being more widely spread across the brightness profile. If the sample contains several scratches that are not at the same angle, it is not possible to obtain a precisely averaged luminance peak value for each individual scratch using only one average direction. Therefore, the averaging algorithm is executed with a plurality of one-dimensional average paths along different directions and records the profile obtained for each. The highest scratch contrast ratio value calculated for each scratch is then recorded. By performing a one-dimensional average along a plurality of directions and recording the peak contrast ratio for each scratch, an appropriate value can be reliably obtained for each scratch regardless of the orientation.

An exemplary algorithm for calculating the contrast ratio from the exported luminance data includes the following steps.
1) Load the luminance data file into the memory.
2) Clip the file to exclude any part beyond the end of the scratch line.
3) Determine the angle of the scratch that extends through the sample relative to the x and y axes of the camera / luminance file.
4) Sum (integrate) the luminance values on all lines of pixels parallel to the scratch and record the number of each. If totals are made on areas of the scratched film, these total values can be relatively large. In areas of film that are not scratched, the sum will be a relatively small number.
5) Set a scratch contrast ratio threshold to determine if there are scratches.
6) For every line of pixels parallel to the scratch, calculate the ratio between the integrated value of the line (step 4 value) and the average integrated value of the surrounding lines. If this ratio is greater than the threshold determined in step 5, scratches are present.
7) Record the contrast ratio of step 6 for each scratch.

Example 1
Nalco 2327 (1200.00 g) was charged to a 2 liter Erlenmeyer flask. 1-Methoxy-2-propanol (1350.3 g), Silane A174 (57.09 g), and PEG2TES (28.19 g) were mixed together and added to the colloidal dispersion with stirring. The contents of the flask were poured into three 32-ounce sealing jars. The jar was heated at 80 ° C. for 16 hours. This resulted in a transparent low viscosity dispersion of surface modified colloidal silica nanoparticles.

  “PEG2TES” means N- (3-triethoxysilylpropyl) methoxyethoxyethyl carbamate. It was prepared as follows. A 250 ml round bottom flask equipped with a magnetic stir bar was charged with 35 g of diethylene glycol methyl ether and 77 g of methyl ethyl ketone, followed by rotary evaporation of a substantial portion of the solvent mixture to remove water. 3- (Triethoxysilyl) propyl isocyanate (68.60 g) was charged to the flask. Dibutyltin dilaurate (about 3 mg) was added and the mixture was stirred. The reaction proceeded with a mild exotherm. The reaction was run for about 16 hours. At that time, no isocyanate was observed by infrared spectroscopy. Solvent residue and alcohol were removed by rotary evaporation at 90 ° C. to give 104.46 g of PEG2TES as a somewhat viscous fluid.

A 10 liter round bottom flask (wide neck) is charged with the contents of three jars (2638 g), 743.00 g of Optical Resin C, and 8.0 g of 2% prostub 5128 in water (Prostab 5128). It is. Water and alcohol were removed by rotary evaporation. In this way, a transparent low-viscosity resin dispersion containing surface-modified colloidal silica nanoparticles was obtained. The resin dispersion contained about 38.5% SiO ₂ and approximately 2% 1-methoxy-2-propanol as measured by gas chromatography. One weight percent of Darocur 1173 was added to the resin dispersion. This example was photocured at ² J / cm ² .

Example 2
Nalco 2327 (224.17 pounds) was charged into a large kettle. Prepare 1-methoxy-2-propanol (252.19 pounds), Silane A174 (9.98 pounds), Silquest A1230 (8.62 pounds), and Prostab 5198 (1.81 g). And added to Nalco 2327 with stirring. The kettle was sealed and heated to 90 ° C. for 16 hours. This resulted in a transparent low viscosity dispersion of modified silica.

Next, 230 pounds of water and alcohol were removed from the kettle by evaporation, followed by the addition of 201.71 pounds of 1-methoxy-2-propanol to the kettle. Next, a 20/60/20 wt% mixture of SR339 / RDX-51027 / SR351 (126.53 pounds) and Prostab 5198 (Prog 5198) (23 g) was charged to the kettle. Water and alcohol were removed again by evaporation. The formulation contained 38.9% by weight SiO ₂ as measured by TGA. The refractive index was 1.517.

Example 3
1% Lucirin TPO-L, based on organic components, was added to the aliquot of Example 2. This example was photocured at ² J / cm ² .

Example 4
0.5% Lucirin TPO-L, based on organic components, was added to the aliquot of Example 2. This example was photocured at 1 J / cm ² .

Example 5
0.5% Lucirin TPO-L, based on organic components, was added to the aliquot of Example 2. This example was photocured at ² J / cm ² .

Example 6
0.5% Lucirin TPO-L, based on organic components, was added to the aliquot of Example 2. This example was photocured at 0.64 J / cm ² .

Example 7
0.5% Lucirin TPO-L, based on organic components, was added to the aliquot of Example 2. This example was photocured at 1.28 J / cm ² .

Example 8
Example 3 was diluted with SR 339 until the SiO ₂ content dropped to 33% by weight. 1% Lucirin TPO-L, based on organic components, was added to this dilution. This example was photocured at ² J / cm ² .

Example 9
1% Lucirin TPO-L (Lucirin TPO-L) was added to a 20/60/20 weight percent mixture of SR339 / RDX-51027 / SR351. This example was photocured at ² J / cm ² .

Comparative Example A
Vikuiti® BEF II 90/50 film (BEF II), sold by 3M, St Paul, Minn., Has a prism angle of 90 degrees and a pitch of 50 micrometers. A micro-replicated prismatic structured brightness enhancement film having a (prism peak-to-peak distance). The prism peak of Comparative Example A is clear.

Comparative Example B
The Vikuiti® Round Brightness Enhancement Film (RBEF) film sold by 3M, St Paul, Minn. Is a 90 degree prism angle. And a micro-replicated prismatic structured brightness enhancement film having a pitch of 50 micrometers. The prism peak of Comparative Example B is round and has a peak radius of 8 microns.

Results The scratch contrast ratio of the above examples was tested as described above in the “Methods” section. These results are listed in Table 1 below.

  Examples 1-9 illustrate articles having scratch resistance. As described above, scratches having a contrast ratio value of 1.00 are invisible to the human eye. Comparative Example A has moderate scratch resistance, while Comparative Example B shows insufficient scratch resistance.

1 is a schematic view of an exemplary microstructured article according to the present invention in a backlight type liquid crystal display. FIG. 1 is a perspective view of an exemplary polymeric structure having a microstructured surface. FIG. 1 is a cross-sectional view of an exemplary microstructured article having prism elements of various heights. FIG. 1 is a cross-sectional view of an exemplary microstructured article having prism elements of various heights. FIG. 1 is a cross-sectional view of an exemplary microstructured article. FIG. 3 is a cross-sectional view of an exemplary microstructured article where prism elements are at different heights and have their bottom surfaces in different planes. 1 is a cross-sectional view of an exemplary microstructured article. 1 is a cross-sectional view of an exemplary microstructured article. 1 is a cross-sectional view of an exemplary microstructured article. It is the schematic of an illumination device provided with a direction change film. It is sectional drawing of a direction change film. It is sectional drawing of another direction change film. FIG. 5 is a schematic flow diagram illustrating one scratch contrast ratio method. FIG. 2 is a schematic diagram of an exemplary apparatus for determining a scratch contrast ratio.

Claims (74)

A polymerized optical film structure having a microstructured surface and a plurality of surface-modified colloidal nanoparticles comprising silica, zirconia, or mixtures thereof;
Durable optical film including   The durable optical film of claim 1, wherein the polymerized optical film structure has a plurality of ridges extending along a first surface.   The durable optical film according to claim 1, wherein the plurality of surface-modified colloidal nanoparticles have a particle size of more than 1 nm and less than 100 nm.   The durable optical film of claim 1, wherein the nanoparticles further comprise titania, antimony oxide, alumina, tin oxide, a mixed metal oxide thereof, or a mixture thereof.   The durable optical film according to claim 1, wherein the silica has a particle size of 5 to 75 nm.   The durable optical film according to claim 1, wherein the silica has a particle size of 10 to 30 nm.   The durable optical film according to claim 1, wherein the zirconia has a particle size of 5 to 50 nm.   The durable optical film according to claim 1, wherein the zirconia has a particle size of 5 to 15 nm.   The durable optical film according to claim 4, wherein a particle size of the titania mixed metal oxide is 5 to 50 nm.   The durable optical film according to claim 4, wherein a particle size of the titania mixed metal oxide is 5 to 15 nm.   The durable optical film of claim 1, wherein the silica accounts for 10-60 wt% of the microstructured surface.   The durable optical film of claim 1, wherein the silica accounts for 10-40 wt% of the microstructured surface.   The durable optical film of claim 1, wherein the zirconia accounts for 10-70 wt% of the microstructured surface.   The durable optical film of claim 1, wherein the zirconia accounts for 30-50 wt% of the microstructured surface.   The durable optical film of claim 4, wherein the titania mixed metal oxide accounts for 10-70 wt% of the microstructured surface.   The durable optical film of claim 4, wherein the titania mixed metal oxide occupies 30-50% by weight of the microstructured surface.   The durable optical film according to claim 1, wherein the surface of the surface-modified colloidal nanoparticles is modified with a surface-modifying treatment agent that can be polymerized with the polymerized optical film structure. Brightness-enhancing polymeric structure having a plurality of surface-modified colloidal nanoparticles,
A brightness enhancement film including   The brightness enhancement film of claim 18, wherein the brightness enhancement polymeric structure has a microstructured surface.   The brightness enhancement film of claim 18, wherein the brightness enhancement polymeric structure has a plurality of ridges extending along the first surface.   The brightness enhancement film of claim 18, wherein the brightness enhancement polymeric structure has a prismatic microstructured surface.   The brightness enhancement film according to claim 18, wherein the plurality of surface-modified colloidal nanoparticles include oxide particles having a particle size of more than 1 nm and less than 100 nm.   The brightness enhancement film according to claim 18, wherein the nanoparticles are silica, zirconia, titania, antimony oxide, alumina, tin oxide, or a mixture thereof.   The brightness enhancement film according to claim 20, wherein the plurality of ridges are prism tops.   The brightness enhancement film according to claim 24, wherein the prism top is round.   The brightness enhancement film according to claim 24, wherein the prism top is flat.   The brightness enhancement film of claim 18, further comprising a base layer optically coupled to the polymeric structure.   28. The brightness enhancement film of claim 27, wherein the base layer comprises styrene-acrylonitrile, cellulose triacetate, polymethyl methacrylate, polyester, polycarbonate, polyethylene naphthalate, naphthalene dicarboxylic acid copolymer, or mixtures thereof. (A) a lighting device having a light emitting surface;
(B) a brightness enhancement film disposed substantially parallel to the light emitting surface, the brightness enhancement film comprising a polymerized structure having a plurality of surface-modified colloidal nanoparticles;
A device comprising:   30. The device of claim 29, wherein the lighting device is a backlight display device.   30. The device of claim 29, wherein the lighting device is a backlight type liquid crystal display device.   30. The device of claim 29, wherein the device is a handheld device.   30. The device of claim 29, wherein the device is a computer display.   30. The device of claim 29, wherein the device is a television. A first surface;
An array of prisms formed in the first surface, wherein
A plurality of first prisms, each having a first prism angular orientation relative to a normal of the first surface;
A plurality of second prisms, each having a second prism angular orientation different from the first angular orientation relative to the normal;
An array of prisms,
A second surface opposite the first surface;
Including
The array of prisms has a plurality of surface-modified colloidal nanoparticles;
Durable light redirecting film. (A) an illumination light source having an optical waveguide having a light emitting surface;
(B) a light redirecting film disposed substantially parallel to the optical waveguide, the redirecting film comprising a first surface, a second surface and a prism formed on the first surface; The direction changing film is disposed in a state where the first surface is associated with the light emitting surface, and as a result, the light emitted from the light emitting surface of the optical waveguide is Hitting the array of prisms and being reflected and refracted by the array of prisms such that the light rays exit the redirecting film through the second surface and substantially along the desired angular direction. A light redirecting film,
With
The array of prisms includes a first plurality of prisms (the first plurality of prisms having a first prism form) and a second plurality of prisms (each of which is different from the first prism form). The first prism configuration and the second prism configuration are configured to substantially uniformly sample the light beam incident on the optical waveguide from the second surface. And the light redirecting film comprises a plurality of surface-modified colloidal nanoparticles,
Illumination device. A retroreflective polymerized structure having a plurality of surface-modified colloidal nanoparticles,
Including retroreflective film.   38. The retroreflective film of claim 37, wherein the retroreflective polymerized structure has a microstructured surface.   38. The retroreflective film of claim 37, wherein the retroreflective polymeric structure has a plurality of ridges extending along the first surface.   38. The retroreflective film of claim 37, wherein the retroreflective polymeric structure has a prismatic microstructured surface.   38. The retroreflective film of claim 37, wherein the plurality of surface modified colloidal nanoparticles comprise oxide particles having a particle size greater than 1 nm and less than 100 nm.   The retroreflective film according to claim 37, wherein the nanoparticles are silica, zirconia, titania, antimony oxide, alumina, tin oxide, or a mixture thereof.   40. The retroreflective film according to claim 39, wherein the plurality of ridges are prism tops.   40. The retroreflective film of claim 38, wherein the microstructured surface is a microstructured corner cube array. A polymerized optical element structure having a microstructured surface and a plurality of surface-modified colloidal nanoparticles comprising silica, zirconia, or mixtures thereof;
A durable optical element.   46. The durable optical element of claim 45, wherein the nanoparticles further comprise titania, antimony oxide, alumina, tin oxide, mixed metal oxides thereof, or mixtures thereof.   46. The durable optical element according to claim 45, wherein a surface of the surface-modified colloidal nanoparticle is modified with a surface-modifying treatment agent that can be polymerized with the polymerized optical element structure.   46. A durable optical element according to claim 45, wherein the polymeric optical element structure has a prismatic microstructured surface.   46. The durable optical element of claim 45, wherein the prismatic microstructured surface has a rounded top.   50. The durable optical element of claim 49, wherein the prismatic microstructured surface has a flat top. A polymerized optical film structure having a microstructured surface and a scratch contrast ratio value in the range of 1.0 to 1.15;
Durable optical film including   52. The durable optical film of claim 51, wherein the polymeric optical film structure has a scratch contrast ratio value in the range of 1.0 to 1.12.   52. The durable optical film of claim 51, wherein the polymerized optical film structure has a scratch contrast ratio value in the range of 1.0 to 1.10.   52. The durable optical film of claim 51, wherein the polymeric optical film structure has a scratch contrast ratio value in the range of 1.0 to 1.05.   52. The durable optical film of claim 51, wherein the polymerized optical film structure includes a plurality of ridges extending along a first surface.   52. The durable optical film of claim 51, wherein the polymerized optical film structure comprises a plurality of surface modified colloidal nanoparticles comprising silica, zirconia, or a mixture thereof.   56. The durable optical film of claim 55, wherein the plurality of ridges extending along the first surface are round.   58. The durable optical film of claim 57, wherein the round ridge has a radius in the range of 4-7 micrometers.   57. The plurality of surface modified colloidal nanoparticles are modified by a first surface modifier and a second surface modifier that is different from the first surface modifier. Durable optical film. A polymerized optical film structure having a microstructured surface comprising a plurality of round prism apexes extending along a first surface and a scratch contrast ratio value in the range of 1.0 to 1.65;
Durable optical film including   61. The durable optical film of claim 60, wherein the polymerized optical film structure has a scratch contrast ratio value in the range of 1.0 to 1.4.   61. The durable optical film of claim 60, wherein the polymeric optical film structure has a scratch contrast ratio value in the range of 1.0 to 1.10.   61. The durable optical film of claim 60, wherein the polymerized optical film structure comprises a plurality of surface modified colloidal nanoparticles comprising silica, zirconia, or a mixture thereof.   61. The durable optical film of claim 60, wherein the round prism top has a radius in the range of 4-7 micrometers.   64. The plurality of surface modified colloidal nanoparticles are modified by a first surface modifier and a second surface modifier different from the first surface modifier. Durable optical film. Polymerized optical film structure having a microstructured surface comprising a plurality of surface modified colloidal nanoparticles comprising silica, zirconia, or a mixture thereof, and a scratch contrast ratio value in the range of 1.0 to 1.65 body,
Durable optical film including   67. The durable optical film of claim 66, wherein the polymeric optical film structure has a scratch contrast ratio value in the range of 1.0 to 1.4.   68. The durable optical film of claim 66, wherein the polymeric optical film structure has a scratch contrast ratio value in the range of 1.0 to 1.10.   68. The durable optical film of claim 66, wherein the silica has a particle size of 5 to 75 nanometers.   68. The durable optical film of claim 66, wherein the silica accounts for 10-60% by weight of the microstructured surface.   68. The durable optical film of claim 66, wherein the polymerized optical film structure includes a plurality of prism tops extending along a first surface.   72. The durable optical film of claim 71, wherein the polymerized optical film structure includes a plurality of round prism tops extending along a first surface.   The durable optical film of claim 72, wherein the round prism top has a radius in the range of 4-7 micrometers.   68. The plurality of surface modified colloidal nanoparticles are modified by a first surface modifier and a second surface modifier that is different from the first surface modifier. Durable optical film.

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