KR20060121919A - Durable optical element - Google Patents

Abstract

A durable optical film (11) includes a polymerized optical film structure having a microstructured surface and a scratch contrast ratio value in a 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 rounded prism apexes microstructure.

Description

Durable Optical Element

The present invention relates generally to durable optical elements. More particularly, the present invention relates to a durable article having a microstructure such as, for example, a brightness enhancing film, an optical illumination film or a reflective element.

Articles having microstructures such as brightness enhancing films, optical turning films or reflective elements are made in various forms. One such form includes a series of intersecting tips and grooves. One example of such a form is a brightness enhancing film having a symmetrical tip and a regular repeating pattern of grooves. Another example includes patterns in which the tip and groove are not symmetrical, and the size, direction or distance between the tip and groove is not uniform.

One disadvantage of current brightness enhancing films and optical light emitting films is that the microstructured tips are sensitive to mechanical damage. For example, minor scratches by nails or hard, relatively sharp edges can cause fractures or cracks in the tips of the microstructures. Conditions sufficient to break the tips of prior art microstructures are those encountered during normal handling of brightness enhancement films such as in the manufacture of liquid crystal displays for portable computers.

If the peaks of the microstructure are broken down, the reflective and refractive properties of the affected peaks are reduced and the transmitted light is scattered at virtually all forward angles. Thus, if a brightness enhancing film is present in the display and the display is looking straight, the scratching of the brightness enhancing film is less bright compared to the undamaged area around the film. However, when the display is seen at an angle near or greater than the “cutoff,” the angle at which the image on the display is no longer visible, the scratches appear substantially brighter than the surrounding, undamaged area of the film. . In both situations, the scratches are very unsatisfactory in terms of aesthetics, and a brightness enhancing film with very few fine scratches or more is unacceptable for use in liquid crystal displays.

Durability was a property that was difficult to quantify. In the past, the durability of an article having a microstructure has been measured by forming a scratch on the microstructure surface and measuring the width or depth of the scratch or the gain associated with the scratched microstructure surface. Conventional durability tests have not always provided a reliable quantification or practical explanation of how scratches on the microstructured surface appear as defects in the optical display.

summary

In general, the present invention relates to durable optical elements useful for a variety of applications, including optical elements such as, for example, microstructured films, as well as displays and other devices comprising such microstructured films.

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

In another embodiment, the durable optical film comprises a surface having a microstructure comprising a plurality of rounded prism vertices extending along the first surface and a polymerized optical film structure having a scratch contrast ratio value in the range of 1.0 to 1.65. do.

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

The above summary of the present invention is not intended to describe each disclosed embodiment or each means of the present invention. The figures, detailed description and examples that follow more particularly exemplify these embodiments.

The invention may be more fully understood in view of the following detailed description of various embodiments of the invention in conjunction with the accompanying drawings.

1 is a schematic diagram of an article having an exemplary microstructure of the present invention in a back-lit liquid crystal display;

2 is a perspective view of an exemplary polymerized structure having a surface with a microstructure;

3 is a cross-sectional view of an article having an exemplary microstructure with prism elements of varying heights;

4 is a cross-sectional view of an article having an exemplary microstructure with prism elements of varying heights;

5 is a cross-sectional view of an article having an exemplary microstructure;

6 is a cross-sectional view of an article having an exemplary microstructure in which the prism elements have various heights and their bottoms on different sides;

7 is a cross-sectional view of an article having an exemplary microstructure;

8 is a cross-sectional view of an article having an exemplary microstructure;

9 is a cross-sectional view of an article having an exemplary microstructure;

10 is a schematic view of a lighting device including a redirecting film;

11 is a cross-sectional view of the redirecting film;

12 is a cross-sectional view of another redirecting film;

FIG. 13 is a schematic flow chart illustrating one scratch contrast ratio method; FIG.

14 is a schematic diagram of an example apparatus for determining a scratch contrast ratio.

While the invention is susceptible to various modifications and alternative forms, specifics thereof have been shown by way of example in the drawings and will be described in detail later. 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 substitutes falling within the spirit and scope of the invention.

The durable article of the present invention is applicable to a variety of applications requiring a durable microstructured film including, for example, a brightness enhancing film, an optical redirecting film, as well as displays and other devices comprising such durable microstructures. I think. While the invention is not so limited, an understanding of various aspects of the invention may be obtained through the description of the examples provided below.

The brightness enhancing film generally improves the on-axis brightness (herein referred to as "luminance") of the lighting device. The brightness enhancing film may be a film having a light transmissive microstructure. The microstructure topography can be a plurality of prisms on the surface of the film that allow the film to be used to redirect light through reflections and refractions. When used in optical displays such as those found in portable computers, watches, and the like, the microstructured optical film confines the light exiting the display into a pair of planes arranged at a desired angle from a vertical axis traveling through the optical display. As a result, the brightness of the optical display can be increased. As a result, light exiting the display outside the acceptable range may be reflected back into the display, where part of it may be "recycled" and returned to the film with the microstructure at an angle that allows it to exit from the display. . This recycling is useful because it can reduce the power consumption required to provide the display with the desired level of brightness.

Retro-reflective films can generally return a significant percentage of incident light at a relatively high angle of incidence regardless of the direction of rotation of the sheet around an axis perpendicular to its major surface. The cube corner retroreflective film may comprise a body portion typically having a surface having a substantially planar substrate surface and a structure comprising a plurality of cube corner elements facing the substrate surface. Each cube corner element may comprise an optical plane that is substantially perpendicular to one reference point, or three, that typically intersects at the vertex. The substrate of the cube corner acts as a hole through which light is transmitted into the cube corner element. In use, light incident on the substrate surface of the sheet is refracted at the substrate surface of the sheet, as described in US Pat. No. 5,898,523, which is incorporated herein by reference, for the cubic corner elements disposed on the sheet. Transmitted through each base and reflected from each of the three perpendicular cube corner optical faces, the direction is redirected towards the light source.

With respect to the terms defined below, these definitions apply unless a different definition is given in the claims or elsewhere herein.

The term "polymer" refers to polymers, copolymers (eg, polymers formed using two or more different monomers), oligomers, and combinations thereof, as well as blends that are miscible by reactions including, for example, coextrusion or transesterification. It will be understood to include polymers, oligomers or copolymers which may be formed in the middle. Blocks and random copolymers are included unless otherwise specified.

The term "refractive index" is defined herein as the absolute index of refraction of a material, which is understood as the ratio of the rate of electromagnetic radiation in free space to the rate of 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 "colloidal" is defined herein to mean particles (main particles or bound main particles) having a diameter of less than about 100 nm.

As used herein, the term "bound particle" refers to a group of two or more major particles that are aggregated and / or agglomerated.

The term "aggregation" as used herein describes a strong association between major particles that can be chemically bound to one another. It is unlikely that the aggregates will collapse into smaller particles.

The term "agglomeration" as used herein refers to a weak association of the major particles that can be held together by charge or polarity, and can collapse into smaller ones.

The term "major particle size" is defined herein as the size of one particle that is not bound.

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

The term "surface modified colloidal nanoparticles" means nanoparticles each having a surface that has been modified such that the nanoparticles provide a stable dispersion.

The term "stable dispersion" is used herein in which colloidal nanoparticles are left under ambient conditions for a period of time, such as about 24 hours—for example, at room temperature (about 20-22 ° C.), without atmospheric pressure, and extreme electromagnetic forces. It is defined as not being aggregated afterwards.

The term "gain" is defined herein as a measure of the brightness increase of the display due to the brightness enhancing film, and is the property of the optical material and also the geometry of the brightness enhancing film. Typically, the viewing angle decreases as the gain increases. High gain is required for Y brightness enhancing films because the improved gain provides an effective increase in the brightness of the backlit display.

Citation of a numerical range by endpoint includes all numbers included within that range (eg 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4 and 5).

As used in this specification and the appended claims, the singular forms “a”, “an” and “an” include plural objects unless the content clearly dictates otherwise. do. Thus, for example, reference to a composition containing "a compound" includes a mixture of two or more compounds. As used in this specification and the appended claims, the term "or" is generally employed in its sense including "and / or" unless the content clearly dictates otherwise.

Unless otherwise indicated, all numbers indicating properties such as amount of ingredients, contrast ratios, etc., used in this specification and claims are to be understood as being modified in all instances by the word "about." Accordingly, unless stated to the contrary, the numerical variables set forth in the foregoing specification and the appended claims are approximations that may vary depending upon the desired properties sought by those skilled in the art using the teachings of the present invention. At the very least, and not as an attempt to limit the application of the principle of equivalents to the scope of the claims, each numerical variable should be considered at least in view of the number of reported significant digits and by applying ordinary approximation techniques. Notwithstanding the numerical ranges and variables setting forth the broad scope of the invention, the numerical values set forth in the specific examples are reported as precisely as possible. However, any numeric value inherently contains a specific error that must necessarily result from the standard deviation shown in its respective test measurement.

Articles with durable microstructures, such as prismatic optical films, provide luminance enhancement functionality by total internal reflection (TIR) from the refracting and protruding prism structures. The structure is vulnerable to damage by compression or cracking, which accounts for some yield loss. Currently, cover sheets are, in many cases, placed on top prism films to protect the prism surface from damage. Since the durability of the prism structure is an important property of the prism film, it is highly desirable to be able to accurately measure the amount. Conventional methods for measuring prism “scratch-tolerance” can detect differences between different prism films, but are not sensitive enough to handle very minor scratches or compressions. The methods and apparatus of the present invention presented herein provide increased sensitivity, and the result corresponds closely to the visibility of scratches on the backlight. Measurement methods and analytical techniques are described below and in the Examples section.

Articles having durable microstructures can be formed from polymerizable compositions. The polymerizable composition can be a substantially solvent free radiation curable inorganic filled organic composite. The organic phase of the composition may consist of reactive diluents, oligomers, crosslinkable monomers and optionally includes photoinitiators. The organic component may have a refractive index of at least 1.50 for most product applications and may exhibit significant durability in the cured form. Lower refractive index compositions, i.e. less than 1.50, are generally easier to make based on the vast selection of materials commercially available in the refractive index region. Lower refractive index resins have utility in some applications as those skilled in the art will recognize. High transmission in the visible light spectrum may also be desirable. Ideally, the composition is any derived, while maintaining a sufficiently high Tg (glass transition temperature) to optimize the desired optical properties and avoid other brightness enhancing product failure modes such as those described in US Pat. No. 5,626,800. Minimize the effects of scratches.

The polymerizable composition may also contain inorganic oxide particles whose size is selected to prevent substantial visible light scattering. The selected inorganic oxide particles can impart an increase in refractive index or scratch resistance or both. It may be desirable to use mixtures of inorganic oxide particle species to optimize optical or material properties and lower the total composition cost. The overall composition of inorganic oxide particles, organic monomers and oligomers preferably has a refractive index greater than 1.49 or greater than 1.56. The use of inorganic oxide filled polymers makes it possible to obtain durability which cannot be obtained using only unfilled resins. The elapsed composite composition has low viscosity, storage stability (compositions that are chemically changed over time, while conforming to all product properties of durability, high visible light transmittance, optical transparency, high refractive index, environmental stability, and light stability. And particles should not settle or phase separate), preferably energy curable in less than 5 minutes and the composition is substantially free of solvent. Compositions with high amounts of multifunctional monomers and reactively functionalized inorganic oxide particles retain the form of existing brightness enhancing films available from 3M, Co. as well as the original master.

The durable article may comprise a polymerized structure having a plurality of surface modified colloidal nanoparticles. The durable article may be an optical element or an optical article consisting of a substrate layer and an optical layer. The substrate layer and the optical layer can be formed from the same or different polymeric materials. Polymerized structures with a plurality of surface modified colloidal nanoparticles have the advantage that they can be formed in a solventless system.

Surface modified colloidal nanoparticles may be present in the polymerized structure in an amount effective to enhance the durability and / or refractive index of the article or optical element. The surface modified colloidal nanoparticles described herein can have a variety of desirable properties including, for example, nanoparticle compatibility with the resin system such that the nanoparticles form a stable dispersion in the resin system, and the surface modification is Reactivity of the nanoparticles with the resin system makes the composite more durable and the appropriate surface modified nanoparticles added to the resin provide a low impact on the uncured composition viscosity. Combinations of surface modifiers can be used to adjust the uncured and cured properties of the composition. Properly surface modified nanoparticles, for example, improve the mechanical strength of the resin, minimize the viscosity change while increasing the solid volume applied to the resin system, and maintain optical transparency while increasing the solid volume applied to the resin system. Etc., the optical and physical properties of the optical element can be improved. In some embodiments, especially solventless systems with nanoparticle loads described herein have a viscosity in the range of 1 to 1000 cps at 85 ° C.

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

Silica nanoparticles may have a particle size of 5 to 75 nm or 10 to 30 nm or 20 nm. Silica nanoparticles may be present in the durable article or optical element in an amount of 10 to 60 weight percent or 10 to 40 weight percent. Silicas for use in the materials of the present invention are commercially available from Nalco Chemical Co., Naperville, Ill. Under the trade name NALCO COLLOIDAL SILICAS. For example, silica includes Nalco products 1040, 1042, 1050, 1060, 2327 and 2329. Suitable fumed silicas are, for example, the AEROSIL series OX-50, -130, -150 and -200, available from DeGussa AG, Hanau, Germany, and Cabot Corp., Tuscola. CAB-O-SPERSE 2095, cab-O-SPERSE A105, CAB-O-SIL M5 available from Ill. .

Zirconia nanoparticles can have a particle size of 5 to 50 nm, or 5 to 15 nm, or 10 nm. Zirconia nanoparticles may be present in an amount from 10 to 70 weight percent, or 30 to 55 weight percent of the durable article or optical element. Zirconia for use in the materials of the present invention is commercially available from Naperville, Ill. Under the trade name Nalc OOSSOO8.

Titania, antimony oxide, alumina, tin oxide and / or mixed metal oxide nanoparticles can have a particle size or combined particle size of 5 to 50 nm, or 5 to 15 nm, or 10 nm. 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 to 70% by weight, or 30 to 50% by weight. Mixed metal oxides for use in the materials of the present invention are commercially available under the trade name Optolake 3 from Catalyst & Chemical Industries Corp., Kawasaki, Japan.

Surface-treating the nano-sized particles can provide stable dispersion in the polymer resin. Preferably, the surface-treatment stabilizes the nanoparticles such that the particles are well dispersed in the polymerizable resin resulting in a substantially homogeneous composition. In addition, the nanoparticles can be modified with a surface treatment agent over at least a portion of the surface thereof so that the stabilized particles can be copolymerized or reacted with the polymerizable resin during curing. In some embodiments, the selection of the second surface modifier can provide a rheology adjustment (ie, to increase or decrease the viscosity) to enable higher nanoparticle loadings at corresponding lower viscosities. In some embodiments, the second surface modifier is different from the first surface modifier.

The nanoparticles can be treated with a surface treatment agent. In general, the surface treating agent is the first end to be attached to the surface of the particle (covalently, ionically or through strong physical adsorption) to impart compatibility with the resin of the particle and / or to react with the resin during curing. Have ends. Examples of the surface treatment agents include alcohols, amines, carboxylic acids, sulfonic acids, phosphonic acids, silanes and titanates. The preferred kind of treatment agent is determined in part by the chemical nature of the metal oxide surface. For silica and other silicon based fillers silane is preferred. In the case of metal oxides such as zirconia, silanes and carboxylic acids are preferred. Surface modification can be carried out following or after mixing with the monomers. In the case of silane, it is preferred to react the silane with the surface of the particles or nanoparticles before introducing them into the resin. The amount of surface modifier required depends on the particle size, particle type, molecular weight of the modifier and the type of modifier. In general, it is preferred that approximately a single layer of modifier be attached to the surface of the particles. The required attachment process or reaction conditions also depend on the surface modifier used. For silanes it is desirable to treat the surface at elevated temperatures under acidic or basic conditions for about 1 to 24 hours. Surface treatment agents such as carboxylic acids do not require elevated temperatures or extended time.

Representative embodiments of suitable surface treatment agents for durable compositions include, for example, isooctyl trimethoxy-silane, N- (3-triethoxysilylpropyl) methoxyethoxyethoxyethyl carbamate (PEG3TES), silquest ) A1230, N- (3-triethoxysilylpropyl) methoxyethoxyethoxyethyl carbamate (PEG2TES), 3- (methacryloyloxy) propyltrimethoxysilane, 3-acryloxypropyltrimethoxy Silane, 3- (methacryloyloxy) propyltriethoxysilane, 3- (methacryloyloxy) propylmethyldimethoxysilane, 3- (acryloyloxypropyl) methyldimethoxysilane, 3- (meth Chryloyloxy) propyldimethylethoxysilane, 3- (methacryloyloxy) propyldimethylethoxysilane, vinyldimethylethoxysilane, phenyltrimethoxysilane, n-octyltrimethoxysilane, dodecyltrimeth Methoxysilane, octadecyltrimethoxysilane, propyltrimethoxysilane, hexyltrimethoxysilane, octa Decyltrimethoxysilane, propyltrimethoxysilane, hexyltrimethoxysilane, vinylmethyldiacetoxysilane, vinylmethyldiethoxysilane, vinyltriacetoxysilane, vinyltriethoxysilane, vinyltriisopropoxysilane, Vinyltrimethoxysilane, vinyltriphenoxysilane, vinyltri-t-butoxysilane, vinyltris-isobutoxysilane, vinyl triisopropeneoxysilane, vinyltris (2-methoxyethoxy) silane, styryl Ethyltrimethoxysilane, mercaptopropyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, acrylic acid, methacrylic acid, oleic acid, stearic acid, dodecanoic acid, 2- [2- (2-methoxy to Methoxy) ethoxy] acetic acid (MEEAA), beta-carboxyethylacrylate, 2- (2-methoxyethoxy) acetic acid, methoxyphenyl acetic acid, and mixtures thereof.

Surface modification of the particles in the colloidal dispersion can be carried out in a number of ways. The method involves a mixture of inorganic dispersions and surface modifiers. Optionally, at this point, for example, co-solvents such as 1-methoxy-2-propanol, ethanol, isopropanol, ethylene glycol, N, N-dimethylacetamide and 1-methyl-2-pyrrolidinone are added Can be. The co-solvent can enhance the solubility of the surface modifier as well as surface modified particles. The mixture comprising the inorganic sol and the surface modifier is then reacted at room temperature or at an elevated temperature, with or without mixing. In one method, the mixture can be reacted at about 85 ° C. for about 24 hours to obtain a surface modified sol. In another method, when the metal oxide is surface modified, the surface treatment of the metal oxide may preferably involve the adsorption of acidic molecules to the particle surface. Surface modification of heavy metal oxides preferably takes place at room temperature.

Surface modification of ZrO 2 and silane can be carried out under acidic or basic conditions. In one case, the silane is heated under acidic conditions for a suitable time. At this time, the dispersion is combined with aqueous ammonia (or other base). The method enables the reaction with silane as well as the removal of acid counter ions from the ZrO 2 surface. In one method, the particles precipitate from the dispersion and separate from the liquid phase.

The surface modified particles can then be introduced into the curable resin in a number of ways. In one preferred aspect, a solvent exchange method is used in which the resin is added to a surface modified sol followed by evaporation to remove water and auxiliary solvent (if used), thus leaving particles dispersed in the polymerizable resin. The evaporation step can be carried out, for example, by distillation, rotary evaporation or oven drying. The surface modified particles may be extracted in a water immiscible solvent and then solvent exchanged as necessary.

Otherwise, another method of introducing the surface modified nanoparticles into a polymerizable resin involves drying the modified particles into a powder and then adding a resin material dispersed therein. The drying step in the process can be carried out by conventional means suitable for the system, for example oven drying or spray drying.

Combinations of surface modifiers may be useful, wherein at least one modifier has a functional group copolymerizable with the curable resin. For example, the polymerizing group can be an ethylenically unsaturated or ring-opening polymerized cyclic functional group. The ethylenically unsaturated polymerizing group can be for example an acrylate or methacrylate or vinyl group. The cyclic functional groups that are ring-opened polymerized generally contain heteroatoms such as oxygen, sulfur or nitrogen, and preferably three-membered rings containing oxygen such as epoxides.

Optical layers or layers with microstructures can be formed from a wide variety of polymeric materials, including a partial list of polymeric materials described herein. The layer can be formed from a high refractive index material comprising monomers such as high refractive index (meth) acrylate monomers, halogenated monomers, and other monomers of high refractive index as known in the art. For example, US Pat. No. 4,568,445, all of which is incorporated herein by reference; 4,721,377; 4,812,032; And 5,424,339. The thickness of the optical or microstructured layer may range from about 10 to about 200 microns.

Suitable polymeric resins for forming the optical or microstructured layer include u.v.-polymerized products of acrylate and / or methacrylate monomers. Suitable resins are brominated, alkyl-substituted phenyl acrylates or methacrylates, such as those described in US Pat. No. 6,355,754, which is incorporated herein by reference (eg, 4,6-dibromo-2-sec-). Butyl phenyl acrylate), methyl styrene monomer, brominated epoxy diacrylate, 2-phenoxyethyl acrylate and 6-functional aromatic urethane acrylate oligomer.

While most kinds 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 may be of a flowable viscosity low enough so that air bubbles are not trapped in the composition and a complete microstructure geometry is obtained. Reactive diluents are typically SR-339, SR-256, SR-379, SR-395, SR-440, SR-506, CD-611, SR- available from Sartomer Co., Exton, PA. Mono- or di-functional monomers such as 212, SR-230, SR-238 and SR-247. Reactive diluents having a refractive index greater than 1.50, such as SR-339, may be preferred. Oligomeric materials, especially those with high refractive index, are also useful. The oligomeric material results in large optical and durable properties for the cured composition. CN-120, CN-104, CN-115, CN-116, CN-117, CN-118, CN-119, CN-970A60, available from Sartomer Co. (Exton, PA) as typical useful oligomer and oligomer combinations Ebecryl 1608, 3200, 3201, 3302, 3605, 3700, 3701, 608, RDX- available from CN-972, CN-973A80, CN-975, and Surface Specialties, Smyrna, GA. 51027, 220, 9220, 4827, 4849, 6602, 6700-20T can be mentioned. In addition, multifunctional crosslinking agents can be used to obtain a composite matrix having a durable high crosslink density. Examples of multifunctional monomers are SR-295, SR-444, SR-351, SR-399, SR-355 and SR-368, available from Sartomer, Inc. (Exton, PA), and Surface Specialties (Smyrna, GA) PETA-K, PETIA and TMPTA-N available from.

Multifunctional monomers can be used as the 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), modified DSC or Dynamic Mechanical Analysis. The polymer composition may be sufficiently crosslinked to provide a glass transition temperature in excess of 45 ° C.

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

Examples of initiators include organic peroxides, azo compounds, quinine, nitro compounds, acyl halides, hydrazones, mercapto compounds, pyryllium compounds, imidazoles, chlorotriazines, benzoin, benzoin alkyl ethers, di-ketones, phenones Etc. can be mentioned. Commercially available photoinitiators are commercially available from Ciba Geigy under the trade names DARACUR 1173, DAROCUR 4265, IRGACURE 651, Acucure 1800, Acucure 369, Acucure 1700 and Acuure. 907, those sold under Accurate 819, are not limited thereto. Phosphine oxide derivatives include LUCIRIN TPO, a 2,4,6-trimethylbenzoyl diphenyl phosphine oxide, available from BASF, Charlotte, N.C. The photoinitiator may be used at a concentration of about 0.1 to 10% by weight or about 0.1 to 5% by weight.

The polymerizable compositions described herein may contain one or more other useful components that may be useful in such polymerizable compositions, as will be appreciated by those skilled in the art. For example, the polymerizable composition may include one or more surfactants, pigments, fillers, polymerization inhibitors, antioxidants, antistatic agents and other possible components. 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 wetting, and enable smoother coatings and fewer coating defects.

The polymerizable composition may 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% when evaluated according to the ASTM D-882-91 method. Hard resin polymers may also exhibit a tensile modulus of greater than 100 kpsi (6.89 × 10 ⁸ Pascals) when evaluated according to ASTM D-882-91.

The optical layer may be in direct contact with the substrate layer or optically aligned with respect to the substrate layer, and may be of a size, shape and thickness that enable the optical layer to direct or direct the flow of light. The optical layer may have a structured or microstructured surface, which may have any number of useful patterns as described below and shown in the figures and examples. The surface with the microstructure may be a plurality of parallel longitudinal peaks extending along the length or width of the film. The peaks may be formed from a plurality of prism vertices. The vertices may be sharp, rounded, flattened or cut. These include regular or irregular prismatic patterns, which may be annular prismatic patterns, cube-corner patterns or any other lenticular microstructures. A useful microstructure is a regular prism pattern that can act as an overall internal reflective film for use as a brightness enhancing film. Another useful microstructure is a corner-cubic prism pattern that can act as an element for use as a retro-reflective or reflective film. Another useful microstructure is a prism pattern that can act as an optical element for use in optical displays. Another useful microstructure is a prism pattern that can act as an optical redirecting film or element for use in an optical display.

The substrate layer may be ones and compositions of a nature suitable for use in optical articles, ie articles designed to control the flow of light. Almost any material can be used as the base material so long as the material is sufficiently optically transparent and structurally strong enough to be assembled into or used within a particular optical article. The base material may be chosen so that it is sufficiently resistant to temperature and aging and that the performance of the optical article does not degrade over time.

The particular chemical composition and thickness of the base material for any optical article may depend on the requirements of the particular optical article being constructed. In other words, it balances the need for strength, transparency, temperature tolerance, surface energy, and adhesion to the optical layer.

Useful substrate materials include, for example, styrene-acrylonitrile, cellulose acetate butyrate, cellulose acetate propionate, cellulose triacetate, polyether sulfones, polymethyl methacrylates, polyurethanes, polyesters, polycarbonates, polyvinyl chlorides, Copolymers or combinations based on polystyrene, polyethylene naphthalate, naphthalene dicarboxylic acid, polycyclo-olefins, polyimides and glass. Optionally, the base material may contain a mixture or combination of these materials. In one embodiment, the substrate may comprise a dispersed phase suspended or dispersed in a multilayer or continuous phase.

In some optical products such as microstructure-containing products such as, for example, brightness enhancing films, examples of preferred substrate materials include polyethylene terephthalate (PET) and polycarbonates. Examples of useful PET films include MELINEX ^™ PET, available from photo grade polyethylene terephthalate and DuPont Films, Wilmington, Del.

Some substrate materials can be optically active and can act as polarizing materials. Many substrates, also referred to herein as films or substrates, are known in the field of optical products to be useful as polarizing materials. Polarization of light through the film can be performed, for example, by including a dichroic polarizer in the film material that selectively absorbs light passing therethrough. Polarization of light can also be achieved by including inorganic materials, such as aligned mica flakes, or by discontinuous phases dispersed within the continuous film, such as droplets of light-controlled liquid crystals dispersed within the continuous film. As another option, the film can be made from fine layers of different materials. The polarizing material in the film can be aligned in the polarization direction by using methods such as, for example, stretching of the film, application of electric or magnetic fields, and coating techniques.

Examples of polarizing films include those described in US Pat. Nos. 5,825,543 and 5,783,120, each of which is incorporated herein by reference. The use of these polarizing films in combination with brightness enhancing films is described in US Pat. No. 6,111,696, which is incorporated herein by reference.

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

The above list of base materials is not exclusive and as well appreciated by those skilled in the art, other polarized and non-polarized films may be useful as substrates for the optical articles of the present invention. The base material may be combined with any number of other films, including, for example, polarizing films for forming a multilayer structure. A simple list of additional substrate materials may include the films described in US Pat. Nos. 5,612,820 and 5,486,949, among others. The thickness of the particular substrate may also depend on the aforementioned requirements of the optical article.

Articles comprising durable microstructures can be configured in a variety of forms, including those having a series of replaceable tips and grooves sufficient to produce a totally internal reflective film. One example of such a film is a brightness enhancing film having a regular repeating pattern of symmetrical tips and grooves, while another example has a pattern where the tips and grooves are not symmetrical. Examples of articles comprising microstructures useful as brightness enhancing films are described by US Pat. Nos. 5,175,030 and 5,183,597, both of which are incorporated herein by reference.

According to the patent, an article comprising a microstructure comprises (a) preparing a polymerizable composition; (b) depositing the polymerizable composition on a mold surface having a negative microstructure of the master in an amount sufficient to just fill the cavity of the master; (c) filling the cavity by moving beads of the polymerizable composition between a preformed substrate and a master, at least one of which is flexible; (d) can be prepared by a method comprising the step of curing the composition. The master may be metallic, such as nickel, nickel-plated copper or brass, or may be a thermoplastic material which is stable under polymerization conditions and preferably has surface energy which allows for clean removal of the polymerized material from the master. The particular method used to make the microstructure topography described herein may be similar to the molding method described in US Pat. No. 5,691,846, which is incorporated herein by reference. The microstructured article according to the invention can be formed from a continuous process in any desired length, for example 5, 10, 100, 1000 meters or more.

Durable articles can be used in applications requiring films with durable microstructures, including, for example, brightness enhancing films. The structure of the durability brightness enhancing film is described in, for example, U.S. Pat.Nos. 5,771,328, 5,917,664, 5,919,551, 6,280,063, and 6,356,391, all of which are incorporated herein by reference. Films with a wide variety of microstructures, such as arcs.

The backlit liquid crystal display, generally indicated at 10 in FIG. 1, comprises a brightness enhancing film 11 of the present invention that can be positioned between the diffuser 12 and the liquid crystal display panel 14. The backlight liquid crystal display also has a light source 16, such as a fluorescent lamp, a light guide 18 for transmitting light for reflection to the liquid crystal display panel 14, and also light towards the liquid crystal display panel. It may include a white reflector 20 for reflecting. The brightness enhancement film 11 increases the brightness of the liquid crystal display panel 14 by aiming the light emitted from the light guide 18. The increased luminance allows for a sharper image to be produced by the liquid crystal display panel and allows the power of the light source 16 to produce the selected luminance to be reduced. The brightness enhancing film 11 of the backlighting liquid crystal display may be a computer display (portable display and computer monitor), a television, a video recorder, a portable communication device, a portable small device (e.g., a mobile phone, a PDA) indicated by a reference sign 21, It is useful for equipment such as automotive and aviation device displays. Although FIG. 1 shows an ambient lighting system, it is understood that the lighting system can directly illuminate the film 11 as used for example in transmissive LCD televisions.

The brightness enhancing film 11 comprises an array of prisms represented by prisms 22, 24, 26 and 28 as shown in FIG. 2. Each prism, such as for example prism 22, has a first side 30 and a second side 32. Prisms 22, 24, 26 and 28 have a body portion 34 having a first surface 36 on which a prism is formed and a second surface 38 that is substantially flat or planar and faces the first surface. It can be formed on.

The linear arrangement of regular right prisms can provide both optical performance and ease of manufacture. Orthogonal prisms mean that the vertex angle θ is nearly 90 °, but this may range from about 70 ° to 120 ° or about 80 ° to 100 °. The prism faces do not have to be identical, and the prisms may be inclined with respect to each other. In addition, although the relationship between the thickness 40 of the film and the height 42 of the prism is not critical, it is preferable to use a thinner film having a well-defined prism face. When the face is projected the angle that the face can form with the surface 38 can be 45 °. However, the angle will vary depending on the pitch of the face or the angle θ of the vertex.

3-9 show exemplary implementations of configurations for optical elements. It is to be noted that these figures are not by size, in particular the size of the structured surface is greatly exaggerated for illustrative purposes. The construction of the optical element may comprise a combination of two or more of the embodiments described below.

Referring to FIG. 3, a representative cross section of a portion of one embodiment of an optical element or light guide film is shown. Film 130 includes a surface 134 having an opposing structure that includes a first surface 132 and a plurality of substantially straightly 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 peaks or vertices 142 of the prism element 136. . 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 shown in FIG. 3, the dihedral angle defined by prism vertex 142 is measured at about 90 °, although in this and other embodiments the exact measurement of the dihedral angle may vary depending on the desired optical parameters. It will be well recognized.

Surface 134 having the structure of film 130 may be described as having a plurality of replaced regions of prismatic elements having peaks located at different distances from a common reference plane. The common reference plane can be chosen arbitrarily. One convenient example of a common reference face is a face that includes a first surface 132; Another is the face defined by the bottom of the lowest groove of the face having the structure, indicated by dashed line 139. In the embodiment shown in FIG. 3, the shorter prism element is measured to be about 50 microns in width and about 25 microns in height as measured from dashed line 139, while the longer prism element is about 50 microns in width and It is measured to be about 26 microns in height. The width of the region containing the longer prism element can be measured between about 1 micron and 300 microns. The width of the region containing the shorter prism element is not critical and can be measured between 200 microns and 4000 microns. In any given implementation, the area of the shorter prism element can be at least as wide as the area of the longer prism element. It will be appreciated by those skilled in the art that the article shown in FIG. 3 is merely exemplary and is not intended to limit the scope of the invention. For example, the height or width of the prism element can vary within the practical limits-it is feasible to machine the prisms precisely in the 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 obtain the desired optical effect.

The width of the first region may be less than about 200 to 300 microns. Under ordinary viewing conditions, the naked eye is difficult to analyze small fluctuations in light intensity that appear in areas less than about 200 to 300 microns in width. Thus, when the width of the first region is reduced to less than about 200 to 300 microns, any optical mating that may appear in the region is not visually detectable under normal viewing conditions.

A surface having a structure of variable height also changes the height of one or more prism elements along its straight extension to create a replaced area that includes portions of the prism element having peaks arranged at varying heights on a conventional reference plane. May be implemented.

4 excludes that the film 150 includes a surface 152 having a structure having an area of relatively shorter prism element 154 separated by an area containing one longer prism element 156. And another embodiment of an optical element similar to FIG. 3. Much like the embodiment shown in FIG. 3, the longer prism element restricts physical access to the surface 152 having the structure of the second sheet of film, thereby providing a visual wet-out state. Reduce the same. The naked eye is sensitive to the change in height of the face in the light guide film, and it has been determined that a relatively large area of longer prism elements will appear as visible lines on the film surface. This does not substantially affect the optical performance of the film, but the line may be undesirable in certain commercial situations. Reducing the width of the area of the longer prism element correspondingly reduces the naked eye's ability to sense the line of film generated by the longer prism element.

5 is a representative example of another embodiment of an optical element in which the prism elements are about the same size but arranged in a repeating staircase or oblique pattern. Film 160 shown in FIG. 5 includes a surface 164 having an opposite structure that includes a first surface 162 and a plurality of substantially straight prism elements 166. Each prism element has opposite sides 168, 168 ′ that intersect at the top thereof to define the prism peak 170. The dihedral angle defined by the opposing sides 168, 168 'is measured to be about 90 degrees. In this embodiment the highest prism may be considered the first region and the adjacent prism may be considered the second region. Again, the first region can be measured to be less than about 200 to 300 microns.

6 shows another embodiment of an optical element. The film 180 disclosed in FIG. 6 includes a surface 184 having a first surface 182 and an opposite structure. The film may be characterized as including a prism element of varying height in a second area comprising a relatively shorter prism element. The surface with the structure shown in FIG. 6 has the additional advantage of substantially reducing the visibility to the naked eye of the lines on the film surface resulting from the height change of the prism element.

7 shows another embodiment of an optical element for providing a smooth cutoff. 7 shows a brightness enhancing film, generally designated 240, in accordance with the present invention. The brightness enhancing film 240 includes a substrate 242 and a surface material 244 having a structure. Substrate 242 may generally be a polyester material, and structured surface material 244 may be ultraviolet-cured acrylic based or other polymeric materials described herein. The outer surface of the substrate 242 is preferably flat, but may also have a structure. In addition, other choices of substrates may be used.

The 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 ° but include angles in the range of 60 ° to 120 °. Between the prisms 246 and 248 is a valley 258. Between the prisms 248 and 250 is a valley 260. The bone 258 can be thought of as having a bone associated with the prism 246 and having a bone angle of 70 °, and the bone 260 having a bone associated with the prism 248 and having a bone angle of 110 °. Although it may be considered, other values may be used. Effectively, the brightness enhancing film 240 increases the apparent on-axis brightness of the background light by reflecting and recycling some of the light and refracting the rest, like the brightness enhancement film of the prior art, while tilting the prism in the other direction ( canted). The effect of tilting the prism is to increase the size of the cone of light output.

8 shows another embodiment of an optical element with rounded prism vertices. The brightness enhancing article 330 features a flexible substrate layer 332 having a pair of opposing surfaces 334, 336 that are both integrally formed with the substrate layer 332. Surface 334 features a series of protruding light-diffusing elements 338. The element may be in the form of “ridges” on a surface made of the same material as layer 332. Surface 336 is characterized by an array of straight prisms having dull or rounded peaks 340 formed integrally with substrate layer 332. The peak is characterized by the width of the string 342, the pitch width 344 of the cross section, the radius of curvature 346 and the root angle 348, where the width of the string is from about 20 to the pitch width of the cross section. Equal to 40%, and the radius of curvature is equal to about 20-50% of the pitch width of the cross section. Root angles range from about 70 to 110 °, or about 85 to 95 °, with a root angle of about 90 ° being preferred. The placement of the prism in the array is chosen to maximize the desired optical performance.

Rounded prism peak brightness enhancing articles generally suffer from reduced gains. However, the addition of high refractive index surface modified colloidal nanoparticles can offset the gain lost from the brightness enhancing article of the rounded prism apex.

9 shows another embodiment of an optical element having a flat or planar prism vertex. The brightness enhancing article 430 features a flexible substrate layer 432 that has a pair of opposing surfaces 434, 436, both formed integrally with the substrate layer 432. Surface 434 features a series of protruding light-diffusing elements 438. The element may be in the form of a "flat ridge" on a surface made of the same material as layer 432. Surface 436 is characterized by an array of straight prisms having flat or planar peaks 440 integrally formed with substrate layer 432. The peaks are characterized by a flattened width 442, a pitch width 444 of the cross section, where the flattened width may be equal to about 0-30% of the pitch width of the cross section.

Another way of extracting light from the light inductor is by using a frustrated total internal reflection (TIR). In one type of frustrated TIR, the light guide has a wedge shape and light rays incident on the thick edge of the light guide are all internally until a critical angle is obtained with respect to the top and bottom surfaces of the light guide. Reflected. The sub-critical angle light rays are then extracted at a glancing angle with respect to the output surface or refracted more concisely from the light inductor. In order to be useful for illuminating a display device, the light beam must then be redirected substantially parallel to the viewing or output axis of the display device. The redirection is generally accomplished using a redirection lens or redirection film.

10-12 show a lighting device comprising a redirecting film. The redirecting film may comprise the materials of 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 the light guide. Light rays exiting the light guide at the deflected angle, which is generally less than 30 ° with respect to the output surface, encounter a prism structure. The light rays are refracted by the first surface of the prism structure and reflected by the second surface of the prism structure such that they are directed to the redirecting lens or film in the desired direction, for example, substantially parallel to the viewing axis of the display. To be guided by.

Referring to FIG. 10, the illumination system 510 includes an optically matched light source 512; Light source reflector 514; A light guide 516 having an output surface 518, a back surface 520 and an input surface 521 and a distal surface 522; A reflector (524) adjacent the back (520); A first light redirecting element 526 having an input surface 528 and an output surface 530; Second light reinducing element 532; And reflective polarizer 534. Light guide 516 may be a wedge or a modification thereof. As is known, the purpose of the light guide is to provide uniform light from the light source 512 over a much larger area than the light source 512, and more particularly over the entire area formed by the output surface 518. To provide a distribution. The light guide 516 also preferably performs the task in a dense and thin package.

The light source 512 may be a CCFL that is cornered to the input surface 521 of the light guide 516, and the lamp reflector 514 is a reflective film that wraps around the light source 512 to form a lamp cavity Can be. The reflector 524 supports the light inductor 516 and may be an efficient back reflector such as, for example, a lambbertian or specular reflective film or a combination thereof.

Edge-paired light traveling from the input surface 521 towards the distal surface 522 is trapped by the TIR. Light is extracted from the light guide 516 by the frustration of Tir. Light rays trapped within the light guide 516 increase the angle of incidence with respect to the plane of the top and bottom walls, due to the wedge angle with each TIR bounce. Thus, the light is eventually refracted out of each output surface 518 and back 520 as it is no longer contained by the TIR. Light refracted out of the back 520 is reflected back or diffusely by the reflector 524 and mostly through the light guide 516. The first light reinducing element 526 is arranged to reinduce light rays exiting the output surface 518 along a direction substantially parallel to the desired viewing direction. The preferred viewing direction may be perpendicular to the output surface 518, but more typically at a slight angle to the output surface 518.

As shown in FIG. 11, the first light reinducing element 526 has an output surface 530 substantially planar and an input surface 528 formed of an array 536 of prisms 538, 540, and 542. It is a light transmissive optical film. The second light redirecting element 532 is a light transmissive film, such as a 3M brightness enhancement film available from Minnesota Mining and Manufacturing Company, St. Paul, Minn. It may also be a brightness enhancing film such as a product (sold as BEFIII). Reflective polarizer 534 may be an inorganic, polymeric, cholesteric liquid crystal reflective polarizer or film. Suitable films are both 3M diffuse reflective polarizer film products (sold under DRPF) or specular reflective polarizer film products (sold under DBEF) available from Minnesota Mining and Manufacturing Company.

Within the arrangement 536, each prism 538, 540, and 542 can be formed with a different angle of view than each of its neighboring prisms. That is, the prism 540 may be formed with different angles (angles C and D) from prisms 538 (angles A and B) and prisms 542 (angles E and F). As shown, prism 538 has an included angle, such as a prism angle, ie 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. While the arrangement 536 is shown to include three different prism structures based on different prism angles, it should be appreciated that in practice any number of different prisms may be used.

Prisms 538, 540, and 542 can also be formed with a common prism angle, but with varying prism directions. For prism 538 the prism axis " L " is shown in FIG. Shown by ^- prism axis (ℓ) are each broken line axes "ℓ ^+" and "ℓ" with respect to, or arranged in a right angle to the output surface 530 as shown with respect to the prism 538, the prism (540 and 542) It may be arranged at an angle to the output surface to face the light source or away from the light source as shown.

Prisms 538, 540, and 542 may be arranged in an array 536 in a regular repeating pattern or cluster 543 of the prism as shown in FIG. 11, wherein the array 536 is the same prism. Although not shown as having the same prism adjacent to, such an arrangement can also be used. Moreover, within the arrangement 536, the prisms 538, 540, and 542 may continuously change from the first prism form, such as the prism form 538, to the second prism, such as the prism form 540, or the like. For example, the prism shape may change in a gradient manner from the first prism shape to the second prism shape. Otherwise, the prism may change in a stepwise manner similar to the form shown in FIG. Within each cluster 543, the prism has one prism pitch, which is selected to be less than the spatial wave frequency. Likewise, the cluster may have a regular cluster pitch. The prism arrangement may be symmetric as shown in FIG. 11 or the prism arrangement may be asymmetric.

The arrangement 536 shown in FIG. 11 has a prism having a symmetrical shape, but a prism arrangement formed in the light reinducing element 526 'such as the arrangement 536' shown in FIG. 12 may be used. Referring to FIG. 12, in array 536 ′, for example, prism 538 ′ has an angle A ′ that is not equal to angle B ′. Similarly for prisms 540 'and 542', each C 'is not equal to each A' and each D ', and each E' is not equal to any of each A ', each C' or each F '. The arrangement 536 'can be advantageously formed using one diamond cutting tool having a predetermined angle, and tilting the tool for each cutting produces a prism with a different prism angle and symmetry. However, it will be appreciated that when using one cutting tool the prism angle will be the same, ie A + B = C + D = E + F.

Although as many prism sizes as necessary may be used to make modifications to the output contours from the light guide 516, it is contemplated that as few as two different prismatic shapes may be used and arranged in clusters within the arrangement 536. . One purpose of the prism lateral variation is to unfold and add varying amounts of optical capability into the first light reinducing element 526. Various forms of prisms 538, 540, and 542 provide a substantially uniform sampling of the input aperture of the light guide, which minimizes the non-uniformity of the light extracted from the light guide 516. The overall result is to effectively minimize the ripple effect, especially near the inlet end 521 of the light guide 516.

13 is a schematic flowchart illustrating one method 600 for determining the scratch contrast ratio. The method generally provides a microstructured article 610, forms a scratch on the microstructured article 620, illuminates the scratched optical film 630, and a plurality of scratch contrast ratios 640. ), Then determining the maximum scratch contrast ratio 650.

An article having a microstructure may be an article having any of the microstructures described herein. Creation of scratches 620 may be performed by any number of methods. Generally, a consistent set of variables is used to create scratches to assess the durability of articles with microstructures. One exemplary set of variables used to create scratches includes using a 0.002 mm radius probe tip. The probe tip can be dragged across the microstructured surface in a direction perpendicular to the prism groove direction under a fixed load of 50 g at 10 fpm. Changing the speed, probe design or probe weight will produce scratches of varying widths and depths and thus change the optical detection results. Thus, one requirement for scratch generation is to use a consistent set of variables for each scratch generation to assess the durability of an article with a microstructure.

The scratched optical film may be illuminated 630 by any number of light sources, such as for example backlighting. The light source can be a diffuse light source that provides near-lambertian light. For example, a detector, such as a camera, may capture the optical image of the surface with the scratched microstructure to provide a measure of the scratch contrast ratio along the length of the scratch 640. The detector and / or scratched film can be rotated off-axis with the detector film to obtain the maximum contrast ratio. The contrast ratio data may then be processed (integrated, normalized, etc.) to determine the maximum contrast ratio 650 for the scratched film based on the contrast ratio data provided by the detector.

Once the image of the scratched sample is obtained, the data can be sent out as a series of luminance values. One direct method for calculating the optical contrast of scratches is to extract luminance line contours over each scratch. In some measurements there is sufficient noise in the data such that the luminance rise due to very minor scratches at any given line contour is not greater than the random noise characteristic. Therefore, it would be necessary to apply some kind of noise-reduction scheme to the data, ideally a scheme that strongly reduces noise due to localized spot defects without weakening the increase in luminance of scratches. This can be done using a one-dimensional averaging method.

Since the scratch is a one-dimensional characteristic, averaging along the direction of the scratch does not reduce the luminance peak of the scratch. However, the method effectively weakens any two-dimensional properties because they only have a limited degree along the direction they average. This kind of averaging increases the sensitivity to spatially extended features, which have very low contrast but are nevertheless easily perceived by human phase-processing mechanisms.

In order to produce real data through one-dimensional averaging, it is important to make the averaging direction equal to the scratches. Otherwise, the scratch peak luminance is weakened because it spreads more widely across the luminance contour. If the sample contains several scratches at unequal angles, it is not possible to obtain exactly averaged luminance peak values for each individual scratch using only one averaging direction. Thus, the averaging algorithm performs a number of one-dimensional averaging processes passing along different directions and records the contours obtained for each. Next, record the highest scratch contrast ratio value calculated for each scratch. The inventors are confident that by performing one-dimensional averaging along multiple directions and recording the peak contrast ratio for each scratch, an accurate value for each scratch is obtained regardless of the direction of the scratch. These contrast ratio values calculated by the algorithm are plotted into a composite, suitably 1D-averaged contour. If there is a lot of noise in the background, the algorithm can define a slight rise or collision in the data as a scratch even if it does not exist, so it is useful to plot both the CR value and the composite luminance contour. By looking at the compound contours, it is very easy to determine which calculated contrast ratio values are due to the actual scratches and which are from other contour artifacts.

One embodiment of a durable optical film includes a polymerized optical film structure having a surface with a microstructure and having a scratch contrast ratio value in the 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. . The optical film can be formed from any of the materials described herein. The optical film may comprise a plurality of surface modified colloidal nanoparticles of silica, zirconia or mixtures thereof, as described herein. The optical film can have any of the microstructures described herein. In one exemplary embodiment, the microstructure includes a plurality of peaks extending along the first surface. The peaks may be rounded to a radius in the range of 4-7 micrometers.

Another embodiment of a durable optical film is a surface having a microstructure comprising a plurality of rounded prism vertices extending along a first surface and a scratch contrast ratio in the range of 1.0 to 1.65, or 1.0 to 1.4, or 1.0 to 1.10. Polymerized optical film structures having values. The optical film may comprise a plurality of surface modified colloidal nanoparticles of silica, zirconia or mixtures thereof as described herein. The optical film can have any of the microstructures described herein. In one exemplary embodiment, the microstructure includes a plurality of peaks extending along the first surface. These peaks may be rounded to a radius in the range of 4-7 micrometers.

In another exemplary embodiment the durable optical film has a surface having a microstructure comprising a plurality of surface modified colloidal nanoparticles of silica, zirconia, or mixtures thereof, and 1.0 to 1.65, or 1.0 to 1.4, or 1.0 to Polymerized optical film structures having a scratch contrast ratio value in the range of 1.10. As described herein, nanoparticles such as, for example, silica may have a particle size of 5 to 75 nm as needed. The durable optical film may include nanoparticles such as silica having a surface having a microstructure of, for example, 10 to 60% by weight. The optical film can have any of the microstructures described herein. In one exemplary embodiment, the microstructure includes a plurality of peaks extending along the first surface. The peaks may be rounded to a radius in the range of 4-7 micrometers.

14 is a schematic diagram of an example apparatus 700 for measuring a scratch contrast ratio. Apparatus 700 generally comprises a polymerized optical film structure having a light source or background light 710, a surface having a microstructure and a scratch on the surface 720 having the microstructure disposed over the background light 710, and And a detector 730 arranged to obtain phase data from the scratch. A detector 730 is disposed over the optical film 720, and a computer 740 is arranged to process image data and calculate the maximum contrast ratio for the scratched optical film 720.

The light source 710 may be a diffused or near-lambert light source, for example a Teflon light box. Detector 730 may be any device capable of capturing an optical image of the surface with the scratched microstructure and providing the optical image as data to computer 740 for data processing. The detector 730 may be located away from the surface with the scratched microstructures by any useful distance, such as for example 5 to 40 cm, or 10 to 20 cm.

The optical film 720 has an axis a-a perpendicular to the surface having the microstructure of the optical film 720. Detector 730 may capture off-axis data by any angle θ. In some embodiments, the scratch is mostly visible or detectable from off-axis angle. The angle may be 1 to 89 °, or 20 to 70 °, or 35 to 60 °, or 40 to 50 °. Detector 730, and / or light source 720 (with the associated platform) may be rotated or moved to achieve an angle θ.

The present invention should not be considered limited to the specific embodiments described herein, but rather should be understood to cover all aspects of the invention as explicitly set forth in the appended claims. Various modifications, equivalent methods, as well as numerous structures to which the present invention may be applied, will be readily apparent to those of ordinary skill in the art upon reviewing this specification.

Manufacture of optical elements

The compositions used in the preparation of exemplary optical elements of the invention are described in the examples shown below. The scratch contrast ratio of the optical element is listed in Table 1 below. The manufacture of exemplary optical elements comprising the microstructures of the prisms is described in U.S. Pat.Nos. 5,175,030 and 5,183,597, or US Patent Application No. 10/436377, filed May 12, 2003, and issued September 12,2003. Similar to those described in US Patent Application No. 10 / 662,085, which is incorporated herein by reference.

Unless otherwise specified, the micro-prism structure has a vertex angle of 90 °, defined by the side slope of the prism with an average distance between adjacent vertices that is about 50 micrometers. The top or apex of the prism has a round of 7 microns radius.

All fractions shown in the examples are by weight unless otherwise specified.

Scratches Contrast  Rain ( CR ) Test Methods

Create scratches

This test method describes a method for scraping various prismatic structures. This test is considered a destructive test. The following materials and devices are generally commercially available unless otherwise specified.

ANORAD Intelligent Axis Control System (Anorad, Shirley, NY)

VIA controller

Sony monitor

50g weight

5.5 "x 7" Prism Film Specimen (sample size may vary)

Scotch Magic Tape 810

TX309 Wipe 9 "x 9"

Plexiglas sample holder 3 "x 3" with black border and matte finish

Plexiglass Alignment Frame 6.5 "x 4"

· ethanol

Diamond Stylus

Process conditions are 0.002 mm radius probe tips with an included angle of 160 °. The probe tip will be dragged at a rate of 10 feet / minute and under a fixed load of 50 g across the sample prism film perpendicular to the prism groove direction or peak length.

The prism film sample is placed in the Plexiglass sample holder, and the groove is placed perpendicular to the stylus movement direction and fixed with Scotch Magic Tape 810. The sample holder is then placed in the alignment frame and on the stage for scratch creation. Level the probe holder. A 50 gram weight was attached to the stylus and the diamond stylus was placed in the probe holder. The Anode Intelligent Axis Control System software runs the system to enter the control speed (10 feet / minute) and scratch length (0.25 inch). The anorad system makes the first scratch. Next, the probe tip is cleaned with ethanol. The plexiglass holder containing the scratched sample is moved to the next position for scratching. Proceed as above to form another scratch at about 1/8 "from the first scratch to form a scratched sample with two scratch lines. Repeat the above steps for each sample.

Optical scratch measurement

This test method describes an optical measurement method for assessing scratches formed on a prism film with a stylus. The following materials and devices are generally commercially available unless otherwise noted.

Optical table

Incandescent light source (Fiber-Lite Model No. 180 Dolan-Jenner Inds.) With regulator box (0.5 inch thick, 6 in x 6 in Teflon cube box light source)-Maximum output fixed (10).

ESP-300 motion controller (Newport Inds.)

ESP-300 Utility Software (Newport Inds.)

. Goniometry Stages and Tables (Newport Inds.)

Radiant imaging camera (Prometric CCD)

Radiant Imaging Software 8.0 (Radiant Imaging Co.)

Round mirror

Waterdrop pattern scale gauge

Plexiglass Sample Holder

Place the Teflon cube on the goniometer and fix it to the optical table. The distance between the Teflon cube light source and the camera lens is 6 1/4 ". Place the plexiglass sample holder described above on the Teflon cube box. Attach a round mirror to the sample holder and activate the light source. A sigma 105 mm lens is Place it on the Prometrics camera and lock the f-stop to f22 Turn on the ESP-300 motion controller and activate the ESP-300 utility software.

The mirror is aligned with the camera lens over the backlight. Turn on the light spot imaging software 8.0, lock the camera in focus mode, and crop the image of the mirror. Advance the X or Y axis of the goniometer using RI 8.0 software so that the mirror is in the center of the lens. This ensures that the sample is in the center of the lens in the angle range of angle ranging from 35 ° to 55 °. Once this is done, the mirror is taken out of the cube box and replaced with a droplet pattern scale gauge. A series of droplet patterns with scales on the scale are selected using the harvesting technique. Focus the camera lens so that the droplet pattern is clear and sharp. Warping will provide inconsistent data. Use ESP software to zero all values displayed in the controller position window box. In the location box window select the jog type and enter a value of 40.000. This will move the goniometer stage at an angle of 40 ° from the axis. Replace the droplet pattern scale gauge with the sample to be analyzed. The light spot imaging software selects a camera calibration characteristic and activates auto calibration. Calibration should be performed after every five measurements have been taken. Using light spot software, harvesting characteristics on the software program are selected and scratch lines are harvested.

Click on the Measurement tab to capture the image. The image will be stored in the light spot software database. After the images are stored in the database, a value of 1.000 is entered in the location box to rotate the goniometer stage and capture another image. The rotation of the protractor stage is continued until an image in each range between 40 ° and 50 ° in 1 ° increments is obtained. For additional samples, repeat the above steps.

By switching the file as a luminance type file, the data file of each phase captured in the light spot software database is sent out, and the luminance file for each image is sent out for further data processing.

Scratches Contrast  Determination of rain

Once the image of the scratched sample is obtained, data can be sent out as an array of luminance values. One direct method for calculating the optical contrast of scratches is to extract the luminance line contour after each scratch. In some measurements, there is enough noise in the data to ensure that the luminance rise due to very minor scratches at any given line contour is no greater than from the random noise characteristic. Therefore, it would be necessary to apply some kind of noise-reduction scheme-ideally, to strongly reduce the noise due to localized point defects without attenuating the increase in brightness of the scratches. This can be done using a one-dimensional average method.

Contrast ratio (CR) refers to a measure of the visibility of scratches on a prism film on a backlight. Scratches can be more immediately apparent at off-axis angles. Contrast ratio is a measure of the luminance of light emitted from the scratched area relative to the background or unscratched area. A contrast ratio of 1.00 is not visible to the naked eye. The greater the value of the contrast ratio, the easier the scratch will be perceived visually. The contrast ratio value can change as a function of the viewing angle, so that the maximum contrast ratio value over all angles is chosen as the contrast ratio for each sample.

Since the scratch is a one-dimensional characteristic, averaging along the direction of the scratch does not reduce the luminance peak of the scratch. However, this method effectively reduces any two-dimensional characteristics, because they have only a limited degree along the direction of the averaging. This type of averaging increases the sensitivity to spatially elongated properties with very low contrast but is nevertheless easily perceived by the human body's phase-processing mechanism.

In order to calculate the actual data through one-dimensional averaging, it is important that the averaging direction is the same as the direction of the scratch. Otherwise, the scratch peak luminance is dimmed by spreading wider across the luminance contour. If one sample has several scratches at different angles, it is impossible to obtain exactly averaged luminance peak values for each individual scratch using only one averaging direction. Thus, the averaging algorithm performs a number of one-dimensional averaging passes along different directions and records the contours obtained for each. Then record the highest scratch contrast ratio value calculated for each scratch. The inventors are confident that by performing a one-dimensional average along multiple directions and recording the maximum contrast ratio for each scratch, an accurate value for each scratch is obtained regardless of the direction.

 Exemplary algorithms for calculating the contrast ratio from the emitted luminance data include:

1) Load luminance data file into memory.

2) Secure the pile to exclude anything beyond the end of the scratch line.

3) Measure the angle at which the scratch progresses in the sample with respect to the x and y axes of the camera / luminance file.

4) Sum (integrate) the luminance values in all lines of pixels parallel to the scratch and record the individual numbers. The summation value can be a relatively large number if the summation is performed over the area of the scratched film. For the area of the film that is not scratched, the summation will result in a relatively small number.

5) Fixed the threshold for the scratch contrast ratio to determine if scratches are present.

6) For every line of pixels parallel to the scratch, calculate the ratio of the integrated value of that line (from step 4) to the integrated average value of the surrounding lines. If the ratio is greater than the threshold determined in step 5, there is a scratch.

7) Record the contrast ratio from step 6 for each scratch.

The following In the embodiment  List of substances used

matter Manufacturer details 1-methoxy-2-propanol Commodity menstruum (Silane A174) 3- (trimethoxysilylpropyl) methacrylate Sigma-Aldrich, Milwaukee, WI Aldrich Catalog # 44015-9 Silane Surface Modifiers CN 120 Sartomer Co. Exton, PA Bisphenol-A epoxy diacrylate oligomer Darocure 1173 Ciba Specialty Chemical, Inc., Tarrytown, NY Photoinitiator Nalco 2327 Ondeo-Nalco Co., Naperville, IL Colloidal Silica Dispersion SR 295 Sartomer (Exton, PA) Pentaerythritol tetraacrylate monomer SR 339 Sartomer (Exton, PA) 2-phenoxyethyl acrylate monomer SR 351 Sartomer (Exton, PA) Trimethylolpropane triacrylate RDX-51027 UCB Corporation (UCB Corp., Smyrna, GA) 2-propenoic acid, (1-methylethylidene) bis [(2,6-dibromo-4,1-phenylene) oxy (2-hydroxy-3,1-propanediyl)] ester monomer Prostab 5128 Shiva Specialty Chemicals (Tarrytown, NY) Hindered Amine Nitroxide Initiator Silkquest A1230 OSI Specialties-Crompton South Charleston, WV Silane surface modifier Lucirin TPO BASF Corp., Mount Olive, NJ Photoinitiator Optical resin C 48 parts Sartomer SR 295 (weight) 35 parts Sartomer CN 120 (weight) 17 parts Sartomer SR 339 (weight)

Example  One

Nalco 2327 (1200.00 g) was placed in a two 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 sealed bottles. The bottle was heated at 80 ° C. for 16 hours. This resulted in a clear, low viscosity dispersion of surface modified colloidal silica nanoparticles.

"PEG2TES" means N- (3-triethoxysilylpropyl) methoxyethoxyethyl carbamate. It was prepared as follows: In a 250 ml round-bottomed flask equipped with a magnetic stir bar, 35 g of diethylene glycol methyl ether and 77 g of methyl ethyl ketone were added, and then a substantial portion of the solvent mixture was moistened by rotary evaporation. Was removed. 3- (triethoxysilyl) propylisocyanate (68.60 g) was added to the flask. Dibutyltin dilaurate (about 3 mg) was added and the mixture was stirred. The reaction proceeded with a mild exothermic reaction. The reaction was carried out for 16 hours, when the infrared spectrum showed no isocyanate. 104.46 g PEG2TES was obtained as a slightly viscous fluid by removal of the remainder of solvent and alcohol by rotary evaporation at 90 ° C.

In a 10 liter round-bottom flask (large), 8.0 g of Prostab 5128 was added with 3 bottles of contents (2638 g), 743.00 g of optical resin C, and 2% aqueous solution. Rotary evaporation removed water and alcohol. 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 about 2% 1-methoxy-2-propanol as measured by gas chromatography. 1% by weight of Darocure 1173 was added to the resin composition. This example was photo-cured at 2 J / cm ² .

Example  2

Nalco 2327 (224.17 lb) was placed in a large metal reactor. 1-Methoxy-2-propanol (252.19 lb), Silane A174 (9.98 lb), Silcast A1230 (8.62 lb), and Prostab 5198 (1.81 g) were prepared and added to Nalco 2327 with stirring. The metal reactor was sealed and heated at 90 ° C. for 16 hours. This resulted in a transparent, low viscosity dispersion of the modified silica.

Next, 230 lb of water and alcohol were removed from the metal reactor by evaporation, and then 201.71 lb of 1-methoxy-2-propanol was added into the metal reactor. Next, a 20/60/20 wt% SR339 / RDX-51027 / SR351 mixture (126.53 lb) and Prostab 5198 (23 g) were placed in the metal reactor. Again water and alcohol were removed by evaporation. The composition contained 38.9 wt.% SiO ₂ as measured by TGA. The refractive index was 1.517.

Example  3

1% Lucirin TPO-L per organic component was added to the aliquots of Example 2. This example was photo-cured at 2 J / cm ² .

Example  4

0.5% Lucirin TPO-L per organic component was added to the aliquot of Example 2. This example was photo-cured at 1 J / cm ² .

Example  5

0.5% Lucirin TPO-L per organic component was added to the aliquot of Example 2. This example was photo-cured at 2 J / cm ² .

Example  6

0.5% Lucirin TPO-L per organic component was added to the aliquot of Example 2. This example was photo-cured at 0.64 J / cm ² .

Example  7

0.5% Lucirin TPO-L per organic component was added to the aliquot of Example 2. This example was photo-cured 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 per organic component was added to the dilution. This example was photo-cured at 2 J / cm ² .

Example  9

To 20/60/20% by weight of SR339 / RDX-51027 / SR351 mixture was added 1% Lucirin TPO-L. This example was photo-cured at 2 J / cm ² .

Comparative example  A

Vikuiti ^TM BEF II 90/50 film (BEF II), sold by 3M (St Paul, MN), has a fineness with a prism angle of 90 ° and a pitch of 50 micrometers (distance between prism peaks). It is a brightness enhancing film having a replicated prism structure. Prism peaks in Comparative Example A were sharp.

Comparative example  B

Vikuiti ^TM rounded brightness enhancement film (RBEF film) sold by 3M (St Paul, MN) has brightness enhancement with a microreplicated prism structure with a prism angle of 90 ° and a pitch of 50 micrometers. It is a film. Prism peaks in Comparative Example B were rounded and had a peak radius of 8 microns.

result

The examples were tested for scratch contrast ratios as described above in the "Methods" section. These results are shown in Table 1 below.

Example Contrast Ratio One 1.00 3 1.10 4 1.32 5 1.21 6 1.43 7 1.39 8 1.22 9 1.31 A 4.79 B 3.35

Examples 1-9 illustrate articles having scratch resistant properties. As described above, scratches with a contrast ratio value of 1.00 are not visible to the naked eye. Comparative Example A has moderate scratch resistance, while Comparative Example B shows poor scratch resistance.

Claims (74)

A durable optical film comprising a polymerized optical film structure having a surface having a microstructure and a plurality of surface modified colloidal nanoparticles of silica, zirconia or mixtures thereof. The durable optical film of claim 1, wherein the polymerized optical film structure has a plurality of peaks extending along the first surface. The durable optical film of claim 1, wherein the plurality of surface modified colloidal nanoparticles have a particle size of greater 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, mixed metal oxides thereof, or mixtures thereof. The durable optical film of claim 1, wherein the silica particle size is 5 to 75 nm. The durable optical film of claim 1, wherein the silica particle size is 10 to 30 nm. The durable optical film of claim 1, wherein the zirconia particle size is 5 to 50 nm. The durable optical film of claim 1, wherein the zirconia particle size is 5 to 15 nm. 5. The durable optical film of claim 4, wherein the titania mixed metal oxide particle size is between 5 and 50 nm. 5. The durable optical film of claim 4, wherein the titania mixed metal oxide particle size is 5 to 15 nm. The durable optical film of claim 1, wherein the silica comprises 10 to 60 wt% of the surface having the microstructure. The durable optical film of claim 1, wherein the silica comprises 10 to 40 wt% of the surface having the microstructure. The durable optical film of claim 1, wherein the zirconia comprises 10 to 70 wt% of the surface having the microstructure. The durable optical film of claim 1, wherein the zirconia accounts for 30 to 50 wt% of the surface having the microstructure. The durable optical film of claim 4, wherein the titania mixed metal oxide comprises 10 to 70 wt% of the surface having the microstructure. 5. The durable optical film of claim 4, wherein the titania mixed metal oxide comprises 30 to 50 wt% of the surface having the microstructure. 10. The durable optical film of claim 1, wherein the surface modified colloidal nanoparticle surface is modified with a surface modification agent capable of polymerizing with the polymerized optical film structure. A brightness enhancing film comprising a polymerized structure to enhance brightness having a plurality of surface modified colloidal nanoparticles. 19. The brightness enhancing film of claim 18, wherein the polymerized structure for enhancing brightness has a surface having a microstructure. 19. The brightness enhancing film of claim 18, wherein the polymerized structure for enhancing brightness has a plurality of peaks extending along a first surface. 19. The brightness enhancing film of claim 18, wherein the polymerized structure for enhancing brightness has a surface having a prismatic microstructure. 19. The brightness enhancing film of claim 18, wherein the plurality of surface modified colloidal nanoparticles comprise oxide particles having a particle size of greater than 1 nm and less than 100 nm. The brightness enhancing film of claim 18 wherein the nanoparticles are silica, zirconia, titania, antimony oxide, alumina, tin oxide, or mixtures thereof. 21. The brightness enhancing film of claim 20 wherein the plurality of peaks are prism vertices. 25. The brightness enhancing film of claim 24 wherein said prism vertices are rounded. 25. The brightness enhancing film of claim 24 wherein said prism vertex is flat. 19. The brightness enhancing film of claim 18, further comprising a substrate layer optically mated to the polymerized structure. 28. The method of claim 27, wherein the substrate layer comprises styrene-acrylonitrile, cellulose triacetate, polymethyl methacrylate, polyester, polycarbonate, polyethylene naphthalate, copolymers of naphthalene dicarboxylic acid, or mixtures thereof. Luminance enhancement film containing. (a) an illumination device having a light emitting surface; And (b) a brightness enhancing film comprising a polymerized structure positioned substantially parallel to said light emitting surface and having a plurality of surface modified colloidal nanoparticles. 30. The device of claim 29, wherein said lighting device is a back-lit display device. 30. The apparatus of claim 29, wherein said illuminating device is a backlit 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. First surface; An array of prisms formed on the first surface (The arrangement of prisms includes a plurality of first prisms having a direction of a first prism angle relative to each first prism perpendicular to the first surface; and Each second prism has a plurality of second prisms having a direction of a second prism angle different from the direction of the first angle with respect to the vertical); And And a second surface opposite said first surface, said array of prisms having a plurality of surface modified colloidal nanoparticles. (a) a light source having a light guide having a light emitting surface; And (b) an optical redirecting film positioned substantially parallel to the light guide, wherein the redirecting film has an array of prisms formed on the first and second surfaces, and on the first surface, the redirecting film comprising: Disposed together with the first surface disposed relative to the light emitting surface such that light rays exiting the light emitting surface of the light guide meet with the array of prisms and are reflected and refracted by the array of prisms such that the light beam passes through the second surface And exit the redirection film along a direction of substantially the desired angle), Wherein the arrangement of prisms includes a first plurality of prisms (each of the first plurality of prisms has a first prism shape) and a second plurality of prisms (each having a second prism shape different from the first prism shape) Wherein the first prism shape and the second prism shape correspond to a substantially uniform sampling of light rays exiting the second surface into the light guide, wherein the optical redirecting film has a plurality of surface modified surfaces. An illumination device, comprising a colloidal nanoparticle. A retro-reflective film comprising a retro-reflective polymerized structure having a plurality of surface modified colloidal nanoparticles. 38. The retro-reflective film of claim 37, wherein said retro-reflective polymerized structure has a surface having a microstructure. 38. The retro-reflective film of claim 37, wherein the retro-reflective polymerized structure has a plurality of peaks extending along the first surface. 38. The retro-reflective film of claim 37, wherein said retro-reflective polymerized structure has a surface having a microstructure of a prism. 38. The retro-reflective film of claim 37, wherein the plurality of surface modified colloidal nanoparticles comprise oxide particles having a particle size of greater than 1 nm and less than 100 nm. 38. The retro-reflective film of claim 37, wherein said nanoparticles are silica, zirconia, titania, antimony oxide, alumina, tin oxide or mixtures thereof. 40. The retro-reflective film of claim 39, wherein the plurality of peaks are prism vertices. 39. The retro-reflective film of claim 38, wherein the microstructured surface is a microstructured corner-cube array. A durable optical element comprising a polymerized optical element structure having a surface having a microstructure and a plurality of surface modified colloidal nanoparticles of silica, zirconia or mixtures thereof. 46. The durable optical element of claim 45 wherein said nanoparticles further comprise titania, antimony oxide, alumina, tin oxide, mixed metal oxides thereof, or mixtures thereof. 46. The durable optical element of claim 45, wherein the surface of the surface modified colloidal nanoparticles is modified with a surface modification agent capable of polymerizing with the polymerized optical element structure. 46. The durable optical element of claim 45, wherein said polymerized optical element structure has a surface having a microstructure of a prism. 46. The durable optical element of claim 45, wherein the surface with prismatic microstructures has rounded vertices. 50. The durable optical element of claim 49 wherein the microstructured surface of the prism has flat vertices. A durable optical film comprising a surface having a microstructure and a polymerized optical film structure having a scratch contrast ratio value in the range of 1.0 to 1.15. 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 1.12. 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 polymerized 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 said polymerized optical film structure includes a plurality of peaks extending along a first surface. 52. The durable optical film of claim 51, wherein said polymerized optical film structure comprises a plurality of surface modified colloidal nanoparticles of silica, zirconia, or mixtures thereof. 57. The durable optical film of claim 55, wherein the plurality of peaks rounded along the first surface. 59. The durable optical film of claim 57, wherein the rounded peaks have a radius in the range of 4-7 micrometers. 59. The durable optical film of claim 56, wherein 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. A durable optical film comprising a surface having a microstructure comprising a plurality of rounded prism vertices extending along a first surface and a polymerized optical film structure having a scratch contrast ratio value in the range of 1.0 to 1.65. 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 polymerized 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 of silica, zirconia or mixtures thereof. 61. The durable optical film of claim 60, wherein the rounded prism vertices have a radius in the range of 4-7 micrometers. 64. The durable optical film of claim 63, wherein 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. A durable optical film comprising a surface having a microstructure comprising a plurality of surface modified colloidal nanoparticles of silica, zirconia or mixtures thereof and a polymerized optical film structure having a scratch contrast ratio value in the range of 1.0 to 1.65. 67. The durable optical film of claim 66, wherein the polymerized optical film structure has a scratch contrast ratio value in the range of 1.0 to 1.4. 67. The durable optical film of claim 66, wherein the polymerized optical film structure has a scratch contrast ratio value in the range of 1.0 to 1.10. 67. The durable optical film of claim 66, wherein the silica particle size is 5-75 nanometers. 67. The durable optical film of claim 66, wherein the silica comprises a surface having a microstructure of 10 to 60 weight percent. 67. The durable optical film of claim 66, wherein the polymerized optical film structure includes a plurality of prism vertices extending along a first surface. 72. The durable optical film of claim 71, wherein the polymerized optical film structure comprises a plurality of rounded prism vertices extending along a first surface. 73. The durable optical film of claim 72, wherein the rounded prism vertices have a radius in the range of 4-7 micrometers. 67. The durable optical film of claim 66, wherein 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.

Images