KR20090125816A - Microstructured optical films comprising biphenyl difunctional monomers - Google Patents

Abstract

Optical films having a polymerized microstructured surface are described. The polymerized microstructured surface comprises the reaction product of a polymerizable resin composition comprising 10% to 100 wt-% of at least one biphenyl di(meth)acrylate monomer. The di(meth)acrylate monomer comprises a core biphenyl structure having two aromatic rings connected with a C-C bond. The biphenyl di(meth)acrylate monomer comprises a sufficient amount of ortho and/or meta (meth)acrylate substituents such that the monomer is a liquid at 25°C.

Description

Microstructured optical film comprising biphenyl difunctional monomer {MICROSTRUCTURED OPTICAL FILMS COMPRISING BIPHENYL DIFUNCTIONAL MONOMERS}

Cross Reference with Related Application

This application claims the benefit of US Provisional Patent Application 60/893593, filed March 9, 2007.

Certain microstructured optical products, such as those described in US Pat. Nos. 5,175,030 and 5,183,597, are commonly referred to as "brightness enhancing films". Brightness enhancing films are backlit flat panel displays such as electroluminescent panels, laptop computer displays, word processors, desktop monitors, televisions, video cameras, as well as liquid crystal displays (LCDs) including those used in automotive and aircraft displays. It is used in many electronic products to increase the brightness.

The brightness enhancing film preferably exhibits unique optical and physical properties, including the index of refraction of the brightness enhancing film that is associated with the resulting brightness gain (ie, "gain"). The improved brightness uses less power to turn on the display, allowing the electronics to operate more efficiently, thereby reducing power consumption, putting less heat load on its components, and extending the life of the electronics. Can be extended.

Brightness enhancing films have been made from high refractive index monomers that are cured or polymerized. Halogenated (eg brominated) monomers or oligomers are often used to achieve refractive indices of, for example, 1.56 or greater. Another method of obtaining a high refractive index composition is a polymerizable organic composition comprising high refractive index nanoparticles as described in US Patent Application Publication Nos. 2006/0204745, 2006/0210726, 2006/0204676, and 2006/0128853. Is to use

Summary of the Invention

An optical film having a polymerized microstructured surface is now described. The polymerized microstructured surface comprises the reaction product of a polymerizable resin composition comprising 10% to 100% by weight of at least one biphenyl di (meth) acrylate monomer. Di (meth) acrylate monomers comprise a core biphenyl structure having two aromatic rings linked by C-C bonds. In one embodiment, the biphenyl di (meth) acrylate monomer is liquid at 25 ° C. In another embodiment, the aromatic ring of the biphenyl di (meth) acrylate monomer includes at least one (meth) acrylate substituent at the ortho or meta position.

The biphenyl di (meth) acrylate monomer has the formula H ₂ C = (R 1) C (O)---Ar-Ar---(O) C (R 1) = CH ₂ , wherein each Ar group is Independently phenyl or naphthyl and R 1 is H or methyl.

Preferred classes of biphenyl di (meth) acrylate monomers have the formula:

Wherein each R 1 is independently H or methyl;

Each R 2 is independently Br;

m ranges from 0 to 4;

Each Q is independently O or S;

n ranges from 0 to 10;

L is a C2 to C12 alkyl group optionally substituted with one or more hydroxyl groups;

Z is an aromatic ring;

t is independently 0 or 1;

At least one of the -Q [LO] n C (O) C (R1) = CH ₂ groups is substituted at the ortho or meta position.

An optical film having a polymerized microstructured surface comprising a reaction product of a polymerizable resin composition comprising certain polymerizable ethylenically unsaturated biphenyl monomers is now described.

The polymeric microstructure may be an optical element or an optical product composed of a base layer and a polymerized microstructured optical layer. The base layer and the optical layer can be formed from the same or different polymeric materials. One preferred optical film having a polymerized microstructured surface is a brightness enhancing film.

The brightness enhancing film generally improves on-axis luminance (hereinafter referred to as "luminance") of the lighting device. The brightness enhancing film may be a light transmissive, microstructured film. The microstructured topography can be a plurality of prisms on the film surface that allow the film to be used to redirect light through reflection and refraction. The height of the prism is typically in the range of about 1 to about 75 micrometers. When used in optical displays such as those found in laptop computers, watches, and the like, microstructured optical films limit the brightness of the optical display by limiting light from the display into a pair of planes positioned at a desired angle from the normal axis through the optical display. Can be increased. As a result, light exiting the display outside the acceptable range is reflected back into the display, where a portion of the light can be "recycled" back to the microstructured film at an angle that allows the light to escape from the display. Such recycling is useful because it can reduce the power consumption required to provide a display with the desired brightness level.

The brightness enhancing film of the present invention generally comprises a base layer (eg, a preformed polymeric film) and an optical layer. The optical layer comprises a regular right prism in a linear array. Each prism includes a first facet and a second facet. The prism is formed on a base having a first surface on which the prism is formed and a second surface that is substantially flat or planar and opposite the first surface. Right angle prism means that the apex angle is typically about 90 °. However, this angle may range from 70 ° to 120 ° and may range from 80 ° to 100 °. These vertices may be pointed, rounded, flat or truncated. For example, the ridges may be rounded to a radius in the range of 4 to 7 to 15 micrometers. The spacing (or pitch) between prism peaks may be between 5 and 300 micrometers. In the case of thin brightness enhancing films, this pitch is preferably 10 to 36 micrometers, more preferably 18 to 24 micrometers. This preferably corresponds to a prism height of about 5 to 18 micrometers, more preferably about 9 to 12 micrometers. The prism faces do not have to be identical, and the prisms may be inclined with respect to each other. The relationship between the overall thickness of the optical article and the height of the prism can vary. However, it is typically desirable to use relatively thin optical layers with a clear prism face. For thin brightness enhancing films on substrates whose thickness is close to 20 to 35 micrometers (1 mil), typical ratios of prism height to total thickness are generally 0.2 to 0.4.

As described in US Pat. No. 5,183,597 (Lu) and US Pat. No. 5,175,030 (Lu et al.), Microstructure-bearing articles (eg, brightness enhancing films) may comprise (a) preparing a polymerizable composition; (b) depositing the polymerizable composition in an amount sufficient to fill the cavity of the master on the microstructured master engraved surface, (c) polymerizing between the preformed base and the master, at least one of which is flexible It can be prepared by a method comprising filling a cavity by moving the beads of the active composition, and (d) curing the composition. The master may be a metal, for example 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 the polymerized material to be removed cleanly from the master. One or more surfaces of the base film may be selectively primed or otherwise treated to promote adhesion of the optical layer to the base.

In some embodiments, the polymerizable resin composition includes surface modified inorganic nanoparticles. In this embodiment, "polymerizable composition" refers to the entire composition, ie the organic component and surface modified inorganic nanoparticles. "Organic component" refers to all components of the composition except surface modified inorganic nanoparticles. Since the surface treatment agent is generally adsorbed or otherwise attached to the surface of the inorganic nanoparticles, the surface treatment agent is not considered as part of the organic component. When inorganic materials such as surface modified inorganic nanoparticles are not present in the composition, the polymerizable composition and the organic component are of the same category.

The polymerizable composition as well as the organic component are preferably substantially free of solvent. “Substantially free of solvent” means that the polymerizable composition is less than 5 wt-%, 4 wt-%, 3 wt-%, 2 wt-%, 1 wt-% and 0.5 wt-% nonpolymerizable (eg, organic) It is said to have a solvent. The concentration of the solvent can be measured by known methods such as gas chromatography (as described in ASTM D5403). Preference is given to solvent concentrations below 0.5% by weight.

The components of the organic component are preferably selected such that the viscosity of the organic component is small. The viscosity of the organic components is less than 1 Pa.s (1000 cp) and typically less than 0.9 Pa.s (900 cp). The viscosity of the organic component may be less than 0.8 Pa.s (800 cp), less than 0.7 Pa.s (700 cp), less than 0.6 Pa.s (600 cp), and less than 0.5 Pa.s (500 cp) at the coating temperature. As used herein, the viscosity is measured on a 25 mm parallel plate (at shear rates up to 1000 sec-1) using a Dynamic Stress Rheometer. In addition, the viscosity of the organic component is typically at least 0.01 Pa · s (10 cp), more typically at least 0.05 Pa · s (50 cp) at the coating temperature.

Coating temperatures typically range from ambient temperature, i.e., 25 ° C. (77 ° F.) to 82 ° C. (180 ° F.). Coating temperatures are less than 170 ° F. (77 ° F.), less than 71 ° C. (160 ° F.), 66 ° C. (150 ° F.), less than 60 ° C. (140 ° F.), less than 54 ° C. (130 ° F.), or less than 49 ° C. (120 ° F.). Can be. If the melting point in the polymerizable composition is below the coating temperature, the organic component may be a solid or may include a solid component. The organic component is preferably a liquid at ambient temperature.

The biphenyl di (meth) acrylate monomer and / or organic component has a refractive index of at least 1.55, 1.56, 1.57, 1.58, 1.59 or 1.60. The polymerizable composition including the high refractive index nanoparticles may have a refractive index as high as 1.70. (Eg, at least 1.61, 1.62, 1.63, 1.64, 1.65, 1.66, 1.67, 1.68, or 1.69). High transmission in the visible light spectrum is typically also preferred.

The polymerizable composition is preferably energy curable within a time scale of less than 5 minutes (eg for a brightness enhancing film having a 75 micron thickness). The polymerizable composition is preferably sufficiently crosslinked to provide a glass transition temperature that is typically above 45 ° C. The glass transition temperature can be measured by methods known in the art, such as differential scanning calorimetry (DSC), controlled DSC, or dynamic mechanical analysis. The polymerizable composition may be polymerized by conventional free radical polymerization methods.

The optical film described herein is made from a polymerizable resin composition comprising at least one bifunctional biphenyl monomer comprising a polymerizable (meth) acrylate substituent. Such monomers include a biphenyl core structure in which two phenyl groups are not fused but connected by a single C-C bond. Such biphenyl monomers of interest do not contain any linking groups between the phenyl groups. Each of the phenyl groups has a substituent comprising a polymerizable (meth) acrylate or thio (meth) acrylate (eg, terminal) group.

At least one aromatic ring contains (meth) acrylate substituents at ortho or meta positions. Biphenyl di (meth) acrylate monomers contain a sufficient amount of ortho and / or meta (meth) acrylate substituents so that the monomers are liquid at 25 ° C. In some embodiments, each (meth) acrylate group comprising a substituent is bonded to an aromatic ring group at an ortho or meta position. The biphenyl di (meth) acrylate monomer may be a high amount of ortho (meth) acrylate substituent (i.e. at least 50%, 60%, 70%, 80%, 90% of the substituents of the biphenyl di (meth) acrylate monomer, Or 95%). In some embodiments, each (meth) acrylate group comprising a substituent is bonded to an aromatic ring group at an ortho or meta position. As the number of meta- and especially para-substituents increases, the viscosity of the organic component can likewise increase. In addition, para-biphenyl di (meth) acrylate monomers are solid at room temperature and have low solubility (ie less than 10%) even with phenoxyethyl acrylate and tetrahydrofurfuryl acrylate.

Biphenyl di (meth) acrylate monomers typically have the general structure of formula (I):

H ₂ C = (R 1) C (O)---Ar-Ar---(O) C (R 1) = CH ₂

Wherein each Ar group is independently phenyl or naphthyl and R 1 is H or methyl.

Preferably, at least one of the — (O) C (R 1) ═CH ₂ groups is bonded to the Ar group at the ortho or meta position. Typically, each-(O) C (R1) = CH ₂ group is bonded to an Ar group at an ortho or meta position. Most preferably, each-(O) C (R1) = CH ₂ group is bonded to an Ar group at the ortho position. In some embodiments, biphenyl groups are bonded directly to each (meth) acrylate or thio (meth) acrylate group. In other embodiments, the linking group may be provided between the phenyl group and the (meth) acrylate group. For example, an alkoxy bond group in which carbon atoms are optionally substituted with hydroxyl may be provided between the phenyl group and the (meth) acrylate group. The linking group typically has a molecular weight (eg, atomic weight) of less than 1200 g / mol. Preferably, the bonding group is a C2-C3 alkoxy group optionally substituted with one or more hydroxyl groups.

In some embodiments, the monomer has the general structure of formula II:

Wherein each R 1 is independently H or methyl;

Each R 2 is independently Br;

m ranges from 0 to 4;

Each Q is independently O or S;

n ranges from 0 to 10;

L is a C2 to C12 alkyl group optionally substituted with one or more hydroxyl groups;

Z is an aromatic ring;

t is independently 0 or 1;

At least one of the -Q [LO] n C (O) C (R1) = CH ₂ groups is substituted at the ortho or meta position. In some embodiments, each -Q [LO] n C (O) C (Rl) = CH ₂ group is substituted at an ortho or meta position. In other embodiments, each —Q [LO] n C (O) C (R 1) ═CH ₂ group is substituted at the ortho position.

In some embodiments, Q is preferably O. In addition, n is typically 0, 1 or 2. L is typically C ₂ or C ₃ . Alternatively, L is typically hydroxyl substituted C ₂ or C ₃ . In some embodiments, Z is preferably fused to a phenyl group to form a binaphthyl core structure.

In some embodiments, it is preferred that the polymerized microstructured surface, the polymerizable resin composition, and the diphenyl monomer are substantially free of bromine (ie, less than 1 weight percent). In another embodiment, the total amount of bromine in combination with chlorine is less than 1 weight percent. In some embodiments, the polymerized microstructured surface or optical film, polymerizable resin composition, and triphenyl monomers are substantially non-halogenated (ie, comprise less than 1% by weight of bromine, chlorine, fluorine, and iodine in total).

Some specific monomers having such a general structure are represented by the following formula:

.

.

.

.

Suitable synthesis of such molecules according to the structures of Formula III and Formula IV is described in the Examples below. Biphenyl di (meth) acrylate monomers according to the structure of formula (V) react 2,2'-dihydroxybiphenyl with epichlorohydrin to produce di-ether epoxides, which then convert this intermediate into the presence of a catalyst It can be prepared by reacting with acrylic acid to give the final monomer. Each binaphthyl molecule (eg, the structure of Formulas VI-VIII) is a 2,2'-dihydroxy-1,1'-binaf rather than 2,2'-dihydroxybiphenyl as starting material. It can be prepared by a similar synthetic method using teal. Other synthetic methods can be used by those skilled in the art.

The organic component comprises one or more biphenyl di (meth) acrylate monomers in an amount of at least 10%, 15%, 20%, 25%, 30%, 35%, or 40% by weight. Although the organic component may consist only of one or more biphenyl di (meth) acrylate monomers, typically at least one biphenyl di (meth) acrylate monomer is replaced by a second (ie different) difunctional (meth) acrylate monomer Or in combination with an oligomer. In this embodiment, the organic component typically comprises up to 75% by weight of biphenyl di (meth) acrylate monomer (s).

The organic component preferably contains at least 5%, 10%, 15%, 20%, and preferably 25% by weight of a second (ie different) difunctional (meth) acrylate monomer or oligomer. Include. The total amount of other difunctional (meth) acrylate monomers typically does not exceed 75% by weight. The organic component preferably comprises at least one aromatic difunctional (meth) acrylate monomer in which the aromatic ring does not comprise a biphenyl group linked by C-C bonds.

In one embodiment, the polymerizable composition comprises an aromatic difunctional (meth) acrylate monomer comprising a major portion having the general structure of the formula:

Wherein each R 1 is independently hydrogen or methyl. Each R 2 is independently hydrogen or bromine. Z is —C (CH ₃ ) ₂ —, —CH ₂ —, —C (O) —, —S—, —S (O) —, or —S (O) ₂ —, and each Q is independently O or S. Typically, the R1 groups are identical. Typically, R2 groups are substantially identical to each other. LO is a coupler. L is independently a branched or linear C ₂ -C ₁₂ alkyl group (ie, C ₂ , C ₃ , C ₄ , C ₅ , C ₆ , C ₇ , C ₈ , C ₉ , C ₁₀ , C ₁₁ , or C ₁₂ ). In addition, the carbon atoms of the alkyl group may be optionally substituted with one or more hydroxyl groups. For example, L can be -CH ₂ CH (OH) CH _2- . Typically, the linkers are identical. Preferably the alkyl group contains up to 8 carbon atoms, more preferably up to 6 carbon atoms. Each n may range from 0 to 10. Each n is preferably at least one. The linker typically has a molecular weight of less than 1200 g / mol. Preferably, the bonding group is a C2-C3 alkoxy group optionally substituted with one or more hydroxyl groups.

Di (meth) acrylate monomers can be synthesized or purchased. As used herein, the main part refers to at least 60 to 70 wt-% of monomers comprising the specific structure (s) just described. It is generally thought that other reaction products also typically exist as by-products of such monomer synthesis. The di (meth) acrylate monomer may be the reaction product of tetrabromobisphenol A diglycidyl ether and acrylic acid. Such monomers are available under the trade designation “RDX-51027” from UCB Corporation, Smyrna, GA, USA. Such materials include 2-propenic acid, (1-methylethylidene) bis [(2,6-dibromo-4,1-phenylene) oxy (2-hydroxy-3,1-propanediyl)] ester It includes the main part.

Alternatively or additionally, the organic component may comprise one or more (meth) acrylated aromatic epoxy oligomers. For example, the (meth) acrylated aromatic epoxy (described as modified epoxy acrylate) is sold under the trade names " CN104 ", " CN120 ", " CN118 ", " CN115 " from Sartomer, Exton, Pa. "And" CN112C60 ". (Meth) acrylated aromatic epoxy oligomers (described as epoxy acrylate oligomers) are available from Satomer under the trade name “CN2204”. In addition, (meth) acrylated aromatic epoxy oligomers (described as epoxy novolac acrylates blended with 40% trimethylolpropane triacrylate) are available from Satomer under the trade name “CN112C60”.

In some embodiments, the aromatic epoxy acrylate is derived from bisphenol A, such as those of the structures previously described. In another embodiment, the aromatic epoxy acrylate is derived from a monomer different from bisphenol A.

One exemplary bisphenol-A ethoxylated diacrylate monomer is commercially available from Sartomer under the trade name "SR602" (viscosity with a viscosity of 0.61 Pa.s (610 cp) at 20 ° C and Tg of 2 ° C). . Another exemplary bisphenol-A ethoxylated diacrylate monomer is commercially available from Sartomer under the trade name "SR601" (viscosity is 1.08 Pa.s (1080 cp) at 20 ° C and Tg is 60 ° C).

In one embodiment, the polymerizable resin composition comprises from 25% to 75% by weight of at least one biphenyl di (meth) acrylate monomer having a (meth) acrylate substituent in the ortho or meta position, and at least one bisphenol A di (meth ) Acrylate monomers 25% to 75% by weight.

The organic component optionally comprises one or more monofunctional diluents in an amount up to about 40% by weight of the total organic component.

Preferred diluents may have a refractive index greater than 1.50 (eg, greater than 1.55). Such reactive diluents may be halogenated or non-halogenated (eg, non-brominated).

Suitable reactive diluents include, for example, phenoxy ethyl (meth) acrylates; Phenoxy-2-methylethyl (meth) acrylate; Phenoxyoxyethyl (meth) acrylate, 3-hydroxy-2-hydroxypropyl (meth) acrylate; Benzyl (meth) acrylate; Phenylthio ethyl acrylate; 2-naphthylthio ethyl acrylate; 1-naphthylthio ethyl acrylate; 2,4,6-tribromophenoxy ethyl acrylate; 2,4-dibromophenoxy ethyl acrylate; 2-bromophenoxy ethyl acrylate; 1-naphthyloxy ethyl acrylate; 2-naphthyloxy ethyl acrylate; Phenoxy 2-methylethyl acrylate; Phenoxyethoxyethyl acrylate; 3-phenoxy-2-hydroxy propyl acrylate; 2,4-dibromo-6-sec-butylphenyl acrylate; 2,4-dibromo-6-isopropylphenyl acrylate; Benzyl acrylate; Phenyl acrylate; 2,4,6-tribromophenyl acrylate is included. Other high refractive index monomers such as pentabromobenzyl acrylate and pentabromophenyl acrylate can also be used.

Preferred diluents are phenoxy ethyl (meth) acrylates, and in particular phenoxy ethyl acrylate (PEA). Phenoxyethyl acrylate is trade name "SR339" from Satomer, trade name "Etermer 210" from Eternal Chemical Co. Ltd .; And Toagosei Co. Ltd. from one or more suppliers, including the trade name "TO-1166". Another preferred diluent is phenylthio ethyl acrylate (PTEA), also available from Cognis.

Another class of high refractive index diluents are monofunctional biphenyls which comprise terminal biphenyl groups linked by a bond or end group comprising two aromatic groups which are not fused by two phenyl groups but connected by a bonding group (eg Q). Monomers. For example, when the bonding group is methane, the end group is a biphenylmethane group. Alternatively, when the linking group is-(C (CH ₃ ) _2- , the end group is 4-cumyl phenyl The monofunctional biphenyl monomer (s) is preferably polymerized by exposure to (e.g. UV) radiation. Possible single ethylenically unsaturated groups also include the monofunctional biphenyl monomer (s) preferably comprise a single (meth) acrylate group or a single thio (meth) acrylate group. .

In some embodiments, biphenyl groups are directly linked to ethylenically unsaturated (eg, (meth) acrylate) groups. Exemplary monomers of this type are 2-phenyl-phenyl acrylate. The biphenyl mono (meth) acrylate or biphenyl thio (meth) acrylate monomers may further comprise alkyl groups optionally substituted with one or more hydroxyl groups (eg 1 to 5 carbons). Exemplary species of this type are 2-phenyl-2-phenoxyethyl acrylate.

In one embodiment, monofunctional biphenyl (meth) acrylate monomers are used having the general formula:

Wherein R 1 is H or CH ₃ ;

X is O or S;

n is in the range of 0 to 10 (eg, n is 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10);

L is an alkyl group having 1 to 5 carbon atoms (ie, methyl group, ethyl group, propyl group, butyl group or pentyl group), optionally substituted with hydroxy.

In another embodiment, the monofunctional biphenyl (meth) acrylate monomer has the general formula:

Wherein R 1 is H or CH ₃ ;

X is O or S;

Q is selected from — (C (CH ₃ ) ₂ —, —CH ₂ , —C (O) —, —S (O) —, and —S (O) ₂ —;

n is in the range of 0 to 10 (eg, n is 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10);

L is an alkyl group having 1 to 5 carbon atoms (ie, methyl group, ethyl group, butyl group or pentyl group), optionally substituted with hydroxy.

Some specific monomers commercially available from Doagosei Co., Ltd., Japan, include, for example, 2-phenyl-phenyl acrylate available under the trade name "TO-2344", 4-(-2- available under the trade name "TO-2345". Phenyl-2-propyl) phenyl acrylate, and 2-phenyl-2-phenoxyethyl acrylate available under the trade name "TO-1463".

Various combinations of aromatic monofunctional (meth) acrylate monomers can be used. For example, a (meth) acrylate monomer comprising a phenyl group can be used in combination with one or more (meth) acrylate monomers comprising a biphenyl group. In addition, two different biphenyl (meth) acrylate monofunctional monomers can be used.

The polymerizable resin may optionally include up to 35% by weight of various other nonhalogenated ethylenically unsaturated monomers. For example, when the (eg prismatic) structure is cast on a polycarbonate preformed polymeric film and photocured, the polymerizable resin composition includes one or more N, N-2 substituted (meth) acrylamide monomers. can do. These include N-alkylacrylamides and N, N-dialkylacrylamides, especially those containing C _1-4 alkyl groups. Examples are N-isopropylacrylamide, Nt-butylacrylamide, N, N-dimethylacrylamide, N, N-diethylacrylamide, N-vinyl pyrrolidone and N-vinyl caprolactam.

The polymerizable resin composition may also optionally include up to 20% by weight of a non-aromatic crosslinker comprising at least three (meth) acrylate groups. Suitable crosslinkers include, for example, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, trimethylolpropane tri (methacrylate), dipentaerythritol penta (meth) acrylate, di Pentaerythritol hexa (meth) acrylate, trimethylolpropane ethoxylate tri (meth) acrylate, glyceryl tri (meth) acrylate, pentaerythritol propoxylate tri (meth) acrylate, and ditrimethyl Olpropane tetra (meth) acrylates are included. Any one or combination of crosslinkers may be used. Since methacrylate groups tend to be less reactive than acrylate groups, the crosslinker (s) are preferably free of methacrylate functional groups.

The organic component may optionally include at least one (eg non-halogenated) crosslinker comprising at least three (meth) acrylate groups. Suitable crosslinkers include, for example, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, trimethylolpropane tri (methacrylate), dipentaerythritol penta (meth) acrylate, di Pentaerythritol hexa (meth) acrylate, trimethylolpropane ethoxylate tri (meth) acrylate, glyceryl tri (meth) acrylate, pentaerythritol propoxylate tri (meth) acrylate, and ditrimethyl Olpropane tetra (meth) acrylates are included. Any one or combination of crosslinkers may be used. Since methacrylate groups tend to be less reactive than acrylate groups, the crosslinker (s) are preferably free of methacrylate functional groups.

Various crosslinkers are commercially available. For example, pentaerythritol triacrylate (PETA) is a trade name "SR444" from Sartomer Company of Exton, Pennsylvania, USA, and is the name of Osaka Organic Chemical Industry, Ltd., Osaka, Japan. Trade name "Viscoat # 300" from Doagosei Company Limited in Tokyo, Japan to trade name "Aronix M-305" and Tradename "Emer 235" from Eternal Chemical Company Limited in Kaohsiung, Taiwan Is available. Trimethylol propane triacrylate (TMPTA) is commercially available from Sartomer Company under the trade name "SR351". TMPTA is also available from Doagosei Company Limited under the trade name "Aronix M-309". In addition, ethoxylated trimethylolpropane triacrylate and ethoxylated pentaerythritol triacrylate are commercially available from Satomer under the trade names "SR454" and "SR494", respectively.

The crosslinker may be present in the polymerizable composition in an amount of at least about 2 wt-%. Typically, the amount of crosslinker is about 25 wt-% or less. The crosslinker may be present in any amount in the range of about 5 wt-% to about 15 wt-%.

The UV curable polymerizable composition includes at least one photoinitiator. Single photoinitiators or blends thereof may be used in the brightness enhancing film of the present invention. In general, the photoinitiator (s) are at least partially soluble (eg, at the processing temperature of the resin) and are substantially colorless after polymerization. The photoinitiator may be colored (eg yellow), provided that the photoinitiator becomes substantially colorless after exposure to a UV light source.

Suitable photoinitiators include monoacylphosphine oxides and bisacylphosphine oxides. Commercially available mono or bisacylphosphine oxide photoinitiators include 2,4,6-trimethylbenzobiphenylphosphate, available under the trade name "Lucirin TPO" from BASF (Charlott, NC). Fin oxides; Ethyl-2,4,6-trimethylbenzoylphenyl phosphinate, also commercially available from BASF under the trade name "Lucirin TPO-L"; And bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide, available under the trade name "Irgacure 819" from Ciba Specialty Chemicals. Other suitable photoinitiators include the trademark "Darocur" from Ciba Specialty Chemicals as well as 2-hydroxy-2-methyl-1-phenyl-propan-1-one available under the trade designation "Darocur 1173" from Ciba Specialty Chemicals. 4265 "," Irgacure 651 "," Irgacure 1800 "," Irgacure 369 "," Irgacure 1700 ", and other photoinitiators available as" Irgacure 907 ".

Photoinitiators can be used at concentrations from about 0.1 to about 10 weight percent. More preferably, the photoinitiator is used at a concentration of about 0.5 to about 5 wt-%. Above 5 wt-% is generally disadvantageous in that it tends to cause yellow discoloration of the brightness enhancing film. Other photoinitiators and photoinitiators can also be suitably used as can be determined by one skilled in the art.

Optionally including surfactants such as fluorine surfactants and silicone-based surfactants in the polymerizable composition to reduce surface tension, improve wettability, enable smoother coatings and fewer coating defects, and the like. can do.

The biphenyl di (meth) acrylate monomers just described are particularly useful for the preparation of non-halogenated high refractive index polymerizable organic compositions. In some embodiments, the composition is free of inorganic nanoparticles.

In another embodiment, the polymerizable composition further comprises inorganic nanoparticles.

Surface modified (eg, colloidal) nanoparticles may be present in the polymeric structure in an amount effective to enhance the durability and / or refractive index of the article or optical element. The total amount of surface modified inorganic nanoparticles may be present in the polymerizable resin or optical article in an amount of at least 10%, 20%, 30%, or 40% by weight. This concentration is typically less than 70% by weight, more typically less than 60% by weight, in order for the polymerizable resin composition to have a viscosity suitable for use in the casting and curing process of the preparation of the microstructured film.

The size of these particles is chosen to avoid significant visible light scattering. It may be desirable to use mixtures of inorganic oxide particle types to optimize optical or material properties and lower overall composition cost. The surface modified colloidal nanoparticles can be (eg, unassociated) oxide particles having primary particle size or associated particle size greater than 1 nm, 5 nm or 10 nm. The primary or associated particle size is generally less than 100 nm, 75 nm, or 50 nm. Typically, the primary or associated particle size is less than 40 nm, 30 nm, or 20 nm. Nanoparticles are preferably unassociated. The measurement can be based on transmission electron microscopy (TEM). Nanoparticles can include metal oxides such as alumina, zirconia, titania, mixtures thereof, or mixed oxides thereof. Surface modified colloidal nanoparticles can be substantially completely compressed.

Fully compressed nanoparticles (except silica) typically have a crystallinity (measured as isolated metal oxide particles) of greater than 55%, preferably greater than 60%, and more preferably greater than 70%. For example, the crystallinity may range up to about 86% or more. Crystallinity can be determined by X-ray diffraction techniques. Compressed crystalline (eg zirconia) nanoparticles have a high refractive index while amorphous nanoparticles typically have a lower refractive index.

Zirconia and titania nanoparticles may have a particle size of 5 to 50 nm, or 5 to 15 nm, or 8 nm to 12 nm. Zirconia nanoparticles may be present in the durable article or optical element in an amount of 10 to 70 weight percent, or 30 to 60 weight percent. Zirconia for use in the compositions and articles of the present invention is under the tradename "Nalco OOSSOO8" from Nalco Chemical Co. and under the tradename "Birder Zirconia" from Buhler AG, Lodzville, Switzerland. Z-WO sol ".

Zirconia particles can be prepared using hydrothermal technology as described in US Patent Application Publication 2006/0148950. Nanoparticles are surface modified. Surface modification includes attaching surface modifiers to inorganic oxide (eg zirconia) particles to modify surface properties. The overall object of surface modification of inorganic particles is to provide a resin with homogeneous components, preferably low viscosity, which can be made into a film having a high brightness (for example using a casting and curing process). .

Nanoparticles are often surface modified to improve compatibility with organic matrix materials. Surface modified nanoparticles are often unassociated, non-aggregated or combinations thereof in organic matrix materials. The resulting light management films comprising these surface modified nanoparticles tend to have high light transparency and low haze. The addition of high refractive index surface modified nanoparticles, such as zirconia, can increase the gain of the brightness enhancing film compared to films containing only polymerized organic materials.

Monocarboxylic acid surface treating agents preferably comprise compatibilizing groups. Monocarboxylic acids may be represented by the formula AB, where the A group is a (eg monocarboxylic acid) group capable of attaching to the surface of the nanoparticles (eg zirconia or titania), and B comprises various different functional groups. It is a commercial group. Carboxylic acid groups can be attached to the surface by adsorption and / or formation of ionic bonds. Compatibilizer group B is generally selected to be compatible with the polymerizable resin of the optical article (eg, improving brightness). Compatibilizing group B may be reactive or non-reactive and may be polar or nonpolar.

Compatibilizing groups B which can impart nonpolar features to zirconia particles include, for example, linear or branched aromatic or aliphatic hydrocarbons. Representative examples of nonpolar modifiers having carboxylic acid functionalities include octanoic acid, dodecanoic acid, stearic acid, oleic acid and combinations thereof.

Compatibilizer group B may optionally be reactive such that it may be copolymerizable with the organic matrix of the optical article (eg, brightness enhancement). For example, free radically polymerizable groups, such as (meth) acrylate compatibilizing groups, may be copolymerized with (meth) acrylate functional organic monomers to produce brightness enhancing articles with good homogeneity.

Suitable surface modifications are described in US Patent Application Publication No. 2007/0112097 and US Patent Application No. 60/891812, filed February 27, 2007.

Surface modified particles can be incorporated into the curable (ie, polymerizable) resin composition in a variety of ways. In a preferred embodiment, a solvent exchange procedure is used whereby the resin is added to the surface modified sol, and then water and cosolvents (if used) are removed via evaporation, thus leaving particles dispersed in the polymerizable resin. . The evaporation step can be for example through distillation, rotary evaporation or oven drying. In another aspect, the surface modified particles can be extracted into a water immiscible solvent and then solvent exchanged if desired. Alternatively, another method of incorporating the surface modified nanoparticles into the polymerizable resin includes drying the modified particles into a powder, then adding a resin material and dispersing the particles in the resin material. The drying step in this method can be accomplished by conventional means suitable for the system, for example oven drying or spray drying.

The optical layer can be in direct contact with the base layer or optically aligned to the base layer, and can be of size, shape and thickness allowing the optical layer to direct or direct the flow of light. The optical layer may have a structured or microstructured surface that may have any of a number of useful patterns as described and shown in US Pat. No. 7,074,463. The microstructured surface can be a plurality of parallel longitudinal ridges extending along the length or width of the film. Such ridges can be formed from the prism apex of a plurality of prisms. Such vertices may be sharp, rounded, flat or truncated. For example, the ridges may be rounded to a radius in the range of 4 to 7 to 15 micrometers.

These include regular or irregular prismatic patterns that can be annular prismatic patterns, cube-corner patterns or any other lenticular microstructures. Useful microstructures are regular prismatic patterns that can act as total internal reflection films for use as brightness enhancing films. Another useful microstructure is a corner-cube prism pattern that can act as a retroreflective film or element for use as a reflective film. Another useful microstructure is a prism pattern that can act as an optical element for use in an optical display. Another useful microstructure is a prism pattern that can act as an optical turning film or element for use in an optical display.

The base layer may be of a nature and composition suitable for use in optical products, ie products designed to regulate the flow of light. As long as the material is sufficiently optically transparent and structurally strong enough to be assembled or used in a particular optical article, almost any material can be used as the base material. Base materials may be selected that have sufficient temperature and resistance to aging so as not to compromise the performance of the optical article over time.

The specific chemical composition and thickness of the base material for any optical product may vary depending on the requirements of the particular optical product being constructed. In other words, the balance between strength, clarity, temperature resistance, surface energy, and adhesion to the optical layer is balanced.

Useful base materials include, for example, styrene-acrylonitrile, cellulose acetate butyrate, cellulose acetate propionate, cellulose triacetate, polyether sulfones, polymethyl methacrylates, polyurethanes, polyesters, polycarbonates, Copolymers or blends based on polyvinyl chloride, 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 base may be multi-layered or contain dispersed components suspended or dispersed in a continuous phase.

For example, for some optical articles, such as microstructure bearing articles, such as brightness enhancing films, examples of preferred base materials include polyethylene terephthalate (PET) and polycarbonate. Examples of useful PET films include photo grade polyethylene terephthalate and Melinex ™ PET available from DuPont Films, Wilmington, Delaware.

Some base materials are optically active and can act as polarizing materials. Many bases, 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 passing through the film can be achieved, for example, by including a dichroic polarizer in the film material that selectively absorbs the passing light. Light polarization can also be achieved by including inorganic materials, such as aligned mica chips, or by droplets of light-controlled liquid crystals dispersed in discontinuous phases, such as continuous films, dispersed in a continuous film. As an alternative, the film can be made from microfine layers of different materials. Polarizing materials in the film can be aligned in polarization orientation by using methods such as, for example, stretching of the film, application of an electric or magnetic field, and coating techniques.

Examples of polarizing films include those described in US Pat. Nos. 5,825,543 and 5,783,120. The use of these polarizing films in combination with brightness enhancement films is described in US Pat. No. 6,111,696.

A second example of a polarizing film that can be used as the base is those films described in US Pat. No. 5,882,774. Commercially available films are multilayer films sold from 3M under the trade name Dual Brightness Enhancement Film (DBEF). The use of such multilayer polarizing optical films in brightness enhancing films is described in US Pat. No. 5,828,488.

A common way of measuring the efficiency of this recycling of light is to measure the gain of the optical film. As used herein, a "relative gain" means that the optical film (or optical film assembly) at the top of the light box for axial luminance measured when no optical film is present on top of the light box. When defined, it is defined as the on-axis brightness as measured by the test method described in the Examples. This definition can be summarized by the following relationship.

Relative gain = (luminance measured using optical film) /

                  (Luminance measured without using an optical film)

In one embodiment, an optical film is described that includes a light transmissive (eg, cured) polymeric material having a microstructured surface. The optical film is a substantially unpolarized film having a single sheet relative gain of at least 1.60. The relative single sheet gain is typically no greater than 2.05. Thus, the single sheet relative gain may also be ranged from any of a set of relative gain values, including 1.65, 1.70, 1.75, 1.80, 1.85, and 1.90 or more.

In another embodiment, the present invention is directed to various assemblies comprising or consisting of two or more films. Each assembly comprises a first microstructured optical film adjacent to a second (eg microstructured or unstructured) optical film.

Adjacent means close enough. Adjacent may include, for example, that the first microstructured optical film is in contact with the second optical film, such as by only stacking the films together or by attaching the films by various means. The film may be attached by mechanical, chemical, thermal, or a combination thereof. Chemical means include various pressure sensitive adhesives, solvent type adhesives, and hot melt adhesives, as well as two-part curable adhesive compositions that crosslink upon exposure to heat, moisture, or radiation. Thermal means include, for example, heated embossed rollers, high frequency (RF) welding, and ultrasonic welding. The optical film may be attached over the entire plane of the film (eg, continuously), only at select points, or only at edges. Alternatively, adjacent optical films can be separated from each other using an air interface. The air interface may be produced by increasing the thickness of either or both of the optical films at the periphery, for example by the application of an adhesive. If the films are laminated rather than laminated together, the air interface between the optical films can be only a few micrometers.

In some embodiments, the first microstructured optical film is adjacent to the second microstructured optical film. In such an assembly, the microstructured surface of the bottom film is preferably disposed adjacent to the unstructured surface of the top film. In embodiments using prismatic microstructured films, the prisms of the films are generally aligned parallel in one main direction, and these prisms are separated by grooves. Generally, it is desirable to align the prisms (or grooves) of the second (eg, bottom) microstructured optical film in the stack such that the prisms are substantially orthogonal to the prisms of the first (eg, top) film. Do. However, other arrangements may be used. For example, the prism of the second optical film is disposed relative to the prism of the second optical film such that the intersection of the groove or prism forms an angle of about 70 ° to about 120 °.

In an assembly of one embodiment, the substantially unpolarized first microstructured optical film is adjacent to the substantially unpolarized second microstructured optical film. The gain of this assembly is at least 2.50. The first optical film may be the same or different than the second optical film. For example, the second film can have different base layer compositions, different microstructured surface compositions and / or have different surface microstructures. The relative gain of this assembly is typically less than 3.32. Thus, the relative gain of such assemblies can be ranged from any of a set of relative gain values including 2.55, 2.60, 2.65, 2.70, 2.75, 2.80, 2.85, 2.90, 2.95, and 3.00 or more. have.

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

The term "microstructure" is used herein as defined and described in US Pat. No. 4,576,850. Thus, this means the configuration of a surface that depicts or characterizes any desired practical purpose or function of an article having a microstructure. Discontinuities, such as protrusions and indentations on the surface of the article, pass through the microstructure in terms of the profile such that the sum of the areas enclosed by the surface profile above the average centerline equals the sum of the areas below the centerline. Deviation from the drawn mean center line, which is essentially parallel to the nominal surface of the article (having a microstructure). The height of the deviation will typically be about +/- 0.005 to +/- 750 micrometers as measured by an optical or electron microscope over a representative feature length of the nominal surface, for example 1-30 cm. . The average centerline may be piano, concave, convex, aspheric, or a combination thereof. The deviation is of a low order, for example +/- 0.005 +/- 0.1 or preferably +/- 0.05 micrometers, the deviation being infrequent or minimal, ie without any significant discontinuity on the surface. An article is an article in which the surface with the microstructure is essentially a "flat" or "smooth" surface, which article is useful, for example, as a precision optical element or elements with a precision optical interface, for example an ophthalmic lens. Articles in which the deviation is of low order and frequently appear include those having antireflective microstructures. The deviation is of a high order, for example from +/− 0.1 to +/− 750 micrometers, and includes a plurality of practical discontinuities, the discontinuities being the same or different, adjacent or spaced in a random or prescribed manner. Articles resulting from microstructures are articles such as retroreflective cube-corner sheets, linear Fresnel lenses, video disks, and brightness enhancing films. The microstructure bearing surface may comprise certain practical discontinuities of both the low and high orders. Surfaces with microstructures may include extended or non-utilitarian discontinuities so long as the amount or type of discontinuities does not significantly interfere with or adversely affect any desired use of the article. have.

"Refractive index" refers to the absolute refractive index of a material (eg, monomer), which is understood as the ratio of the speed of electromagnetic radiation in free space to the speed of electromagnetic radiation in the material. Refractive indices can be measured using known methods, and generally in the visible region Abbe refractometer or Bausch and Lomb refractometer (CAT No. 33.46.10) (e.g., Pennsylvania, USA) Measurements are made using Fischer Instruments, Pittsburgh. It is generally known that the measured refractive indices may vary to some extent depending on the instrument.

"(Meth) acrylate" refers to both acrylate and methacrylate compounds.

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

"Surface modified colloidal nanoparticles" refer to nanoparticles each having a surface that has been modified such that the nanoparticles provide a stable dispersion.

A "stable dispersion" refers to agglomeration of colloidal nanoparticles after standing for a period of time, for example about 24 hours, under ambient conditions such as room temperature (about 20-22 ° C.) and atmospheric pressure and no extreme electromagnetic forces. As a dispersion, which is not defined.

"Aggregation" refers to a strong association between primary particles that can chemically bind to each other. Collapse of the aggregates into smaller particles is difficult to achieve.

"Agglomeration" refers to a weak association between primary particles that can be bound by charge or polarity and disintegrate into smaller entities.

"Primary particle size" refers to the average diameter of one (unaggregated, non-aggregated) particle.

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

Unless otherwise indicated, all numbers expressing quantities of ingredients, measurements of properties, and the like, as used in this specification and claims, are to be understood as being modified in all instances by the term "about."

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 properly set forth in the appended claims. Various modifications, equivalent processes, as well as various structures that can be applied to the present invention upon overview of the specification, will be readily apparent to those skilled in the art related to the present invention.

Synthesis of Biphenyl Di (meth) acrylate Monomer

1.2,2'- Dihydroxyethoxy - Biphenyl  Produce

2,2'-dihydroxy-biphenyl (500 g, 2.68 mole, in a 2000 ml three necked round bottom flask equipped with an overhead stirrer, temperature probe and heating mantel) 1.0 eq), ethylene carbonate (520.2 g, 5.9 mole, 2.2 eq.), Potassium iodide (5 g, 0.03 mole, 0.01 eq.), N, N-dimethyl formamide (DMF) (47 g, 50 Ml) was added and heated to 150 ° C. The reaction was monitored by GC and after 4 hours the reaction was complete. The reaction was cooled to 40 ° C., 1000 ml of ethyl acetate was added and washed three times with 500 ml of sodium chloride brine. Ethyl acetate was dried over MgSO ₄ , filtered and concentrated in vacuo to recover the dark brown product (736 g, 99%).

2. 2,2'- Diethoxy - Biphenyl Diacrylate  (" BPDA -1 ") manufacturing

2,2'-dihydroxyethoxy-biphenyl (368 g, 1.34 mole, 1.0 eq.) In a 2000 ml three neck round bottom flask equipped with an overhead stirrer, dean stark trap and temperature probe. , Toluene (700 g), ProStab 5198 (0.023 g), aluminum N-nitrosophenylhydroxylamine (NPAL) (0.059 g), manganese acetate (0.023 g), acrylic acid (212.7 g, 2.95 mole, 2.2 eq), p-toluene sulfonic acid (pTSA, 23.1 g, 0.13 mole, 0.1 eq.) Was added and heated to reflux. After 2.5 hours the reaction comprised about 45/45 product / middle product and 10% starting material. The reaction was treated with acrylic acid (26 g) and pTSA (5 g) and reflux was continued. No further conversion to the product was observed. Acrylic acid (50 g) and methane sulfonic acid (5 g) were added. Water was collected continuously with the Dean Stark trap. When performing the reaction overnight, the product was about 75% product and 7% mono acrylate. The reaction was washed three times with sodium chloride brine (200 mL), three times with brine (200 mL) containing some 1N NaOH, three times with saturated sodium carbonate (200 mL), dried over MgSO ₄ (5 g), The product was recovered by filtration and concentration in vacuo. The product (500 g) was purified by a series of three columns eluting with 50% hexanes / chloroform to recover 220 g of 92% purity (GC) product and three other fractions of lower purity. The refractive index of the (ie uncured) monomer was measured to be 1.559.

3. 2,2'- Biphenyl Diacrylate  (" BPDA -2 ") manufacturing

1000 ml 3-neck round bottom flask equipped with overhead stirrer and temperature probe in 2,2'-dihydroxy-biphenyl (50 g), prostop 5198 (0.02 g), DMF (150 ml) and triethylamine (59.8 g) was added. The reaction was cooled to below 0 C using a methanol / dry ice bath and acryloyl chloride (51 g) was added slowly. According to GC, the reaction was mostly complete, with monoacrylate being about 15%. Triethylamine (10 g) was added followed by acryloyl chloride (9 g). According to GC, the reaction was shown to be complete. The reaction product was treated with (300 mL) methyl t-butyl ether and (300 mL) DI water. The organic portion was separated and washed five times with 200 ml sodium chloride brine. The organic portion was treated with 50 g filter aid, mixed and filtered through a thin pad of silica gel. The filtrate was concentrated in vacuo to recover a yellow oil. This oil (69 g) was micronized in 300 ml chloroform, filtered through a short silica gel column (5.5 in diameter by 10.16 cm (4 in) thick) and eluted with chloroform / heptane. The product (52 g) was recovered by concentrating the eluate in vacuo. GC showed that the product was less than 98%. The refractive index of the (ie uncured) monomer was measured at 1.571.

Polymerizable  Resin composition

Polymerizable Resin Composition 1: 50 parts of BPDA-2, 25 parts of CN120 (epoxy acrylate available from Sartomer Company, Exton, Pa., Viscosities at 2.15 Pa.s (2150 cp) and refractive index Reported by Satomer as 1.5556 and Tg is 60 ° C., 25 parts of SR601 (ethoxylated bisphenol A diacrylate, available from Sartomer Company, viscosity at 25 ° C. is 1.08 Pa.s (1080 cps) and refractive index) This was reported to be 1.5340 and a Tg of 60 ° C., and 0.6 parts of Darocur 4265 (available from Ciba Specialty Chemicals, Tarrytown, NY) together in a amber jar. The refractive index of this resin composition was measured at 1.560.

Polymeric Resin Composition 2: 50 parts of BPDA-1, 25 parts of CN120, 25 parts of SR601, and 0.6 parts of Darocur 4265 were thoroughly mixed together in an amber bottle. The refractive index of this resin composition was measured at 1.553.

Polymeric Resin Composition 3: 50 parts of BPDA-1, 50 parts of CN120, and 0.6 parts of Darocure 4265 were mixed together thoroughly in an amber bottle. The refractive index of this resin composition was measured at 1.558.

Preparation of Optical Film Samples of Polymerizable Resin Compositions 1 to 3:

The brightness improving film sample was produced using the polymeric resin compositions 1-3. About 3 g of warmed resin is applied to a 0.05 mm (2 mil) primed PET (polyester) film available under the trade name "Mellynex 623" from DuPont, and is available commercially from Vikuiti TBEF-90 / Placement was made for a microstructured tool with a 90/24 pattern similar to 24. PET, resin, and tools were passed through a heated laminator set to about 65.5 ° C. (150 ° F.) to form samples of uniform thickness. The tool containing the film and the coated resin sample was passed through a Fusion UV processor containing two 23.6 W / cm (600 W / 10 in) D-bulbs at 914 cm / m (30 fpm). The film was cured. PET and cured resin were removed from the tool and cut to obtain a sample. The test method used to evaluate the film is as follows:

ZrO ₂  Sol

The ZrO ₂ sol used in the examples had the following properties (in the light correlation spectroscopy (PCS) and X-ray diffraction and thermogravimetric methods described in US Patent Application Publication No. 2006/0204745 and US Patent Application No. 11/078468). According to measurement):

The preparation of ZrO ₂ sol is described in US Patent Application Publication No. 2006/0204745 and US Patent Application No. 11/078468, filed March 11, 2005.

Polymerizable Resin Composition 4

ZrO2 sol (500 g with 40.87% solids), succinic mono- [2- (2-methoxy-ethoxy) -ethyl] ester (43.2 g with 50% solids in 1-methoxy-2-propanol), 1 -Methoxy-2-propanol (345 g), succinic mono- (2-acryloyloxy-ethyl) ester (62.6 g in 50% solids in 1-methoxy-2-propanol), 2-phenyl-phenyl A 50/50 blend (128.3 g) and prostop 5198 (0.08 g) of acrylate / diethoxy biphenyl diacrylate (BPDA-1) were charged to a three neck 2 L RB flask. Water and alcohol were removed via vacuum distillation so that the resulting dispersion was approximately 53.0% ZrO 2 in acrylate resin. The refractive index of the final blend was measured at 1.657 using a Bausch and Lom refractometer (CAT No. 33.46.10). 28.4 g of the resin blend was added to the amber bottle. 0.71 g of SR 238 (HDODA available from Sartomer Company) and 0.14 g of Darocure 1173 were also added to the amber bottle and mixed thoroughly. The refractive index of the blended resin was measured at 1.647.

Polymerizable  Preparation of Optical Film Samples of Resin Composition 4:

8 "20.3 cm × 27.9 cm (8") consisting of a linear row of 90 degree prisms with a nominal pitch spacing of 50 micrometers, similar to the prism geometric pattern found in Viquity BEF II (available from 3M Company, St. Paul, Minn.) X 11 ") metal master was placed on a hot plate and heated to 60 ° C (140 ° F). 4 ml of beads of each polymerizable resin from Example 1 or Example 2 were applied to the master tool using a disposable pipette. Next, 500 gauge PET, available as Mellinex 623 from Dupont Teijin Films, was placed on the resin beads and master tool.

The PET film was oriented so that the linear prism was oriented approximately perpendicular (90 ° +/− 20 °) to the high gain axis of the film. The master tool, resin, and PET were then passed through a heated nip roll at 71.1 ° C. (160 ° F.) with sufficient force to completely fill the master tool while removing any entrained air. The charged master tool was then line speed 15.2 m / min (50 fpm) using a 236.2 W / cm (600 W / in) variable power supply available from Fusion U Systems, Inc., Gettersburg, Maryland, USA. Were exposed to ultraviolet radiation from the "D-bulb" for two passes. The PET film was then removed by hand from the master tool. The prism coating formed on the PET film had a coating thickness of approximately 25 micrometers.

Gain test method

Measuring the optical performance of films using the SpectraScan ™ PR-650 SpectraColorimeter with MS-75 lens, available from Photo Research, Inc. of Chatsworth, CA, USA It was. The film was placed on top of the diffusely transmissive hollow light box. Diffuse transmission and reflection of the light box can be described as Lambertian. The light box was a six-sided hollow cube measuring approximately 12.5 cm × 12.5 cm × 11.5 cm (L × W × H) made from a diffused PTFE plate about 6 mm thick. One side of the box is selected as the sample surface. The hollow light box had a diffuse reflectance of about 0.83 measured at the sample surface (eg, about 83%, average over a wavelength range of 400-700 nm, measurement method described below). During the gain test, the box was illuminated from the inside through a circular hole of about 1 cm in the bottom of the box (opposite the sample surface with light directed from the inside towards the sample surface). Such illumination is provided using a stabilized broadband incandescent light source attached to a bundle of optical fibers used to direct light (from Schott-Fostec LLC, Marlboro, Mass., USA and Auburn, NY, USA). Fostec DCR-II) with a fiber bundle extension of about 1 cm in diameter. A standard linear absorbing polarizer (eg, Melles Griot 03 FPG 007) is placed between the sample box and the camera. The camera is focused on the sample surface of the light box at a distance of about 34 cm and the absorbing polarizer is placed about 2.5 cm from the camera lens. The luminance of the illuminated light box measured using a polarizer in situ without sample film was greater than 150 cd / m 2. When the sample film was placed in parallel with the box sample surface so that the sample film was in general contact with the box, the sample brightness was measured with PR-650 at normal incidence to the plane of the box sample surface. The relative gain is calculated by comparing this sample luminance with the luminance measured in the same manner as in the light box alone. The entire measurement was performed in a dark enclosure to remove the missing light source.

15.25 cm (6 inch) spectralon-coated integrating sphere, stabilized broadband halogen light source, and light source all supplied by Labsphere (Sherton, New Hampshire, USA) Using a power supply device, the diffuse reflectance of the light box was measured. The integrating sphere has three open ports: one port for incident light (2.5 cm diameter), one port (2.5 cm diameter) 90 degrees along the second axis as a detector port, and a sample port (5 cm diameter) It had a third port 90 degrees along the third axis (ie, perpendicular to the first two axes). The PR-650 spectrophotometer (same as above) was focused on the detector port at a distance of about 38 cm. The reflection efficiency of the integrating sphere was calculated using a calibrated reflectance standard (SRT-99-050) from the lab sphere with about 99% diffuse reflectance. This standard was calibrated by Labsphere and traceable to the NIST standard (SRS-99-020-REFL-51). The reflection efficiency of the integrating sphere was calculated as follows:

Sphere luminance ratio = 1 / (1-R sphere * R standard)

The spherical luminance ratio in this case is the ratio obtained by dividing the luminance measured at the detector port with the reference sample covering the sample port by the luminance measured at the detector port without the sample covering the sample port. Knowing this luminance ratio and the reflectance (R standard) of the corrected standard, the reflection efficiency (R sphere) of the integrating sphere can be calculated. The value is then used again in a similar formula to measure the reflectance of the sample, in this case the PTFE light box:

Sphere Luminance Ratio = 1 / (1-R sphere * R sample)

Here, the spherical luminance ratio is measured as the ratio of the luminance at the detector divided by the luminance measured in the absence of the sample with the sample at the sample port. Since we know the R sphere from above, we can calculate the R sample. These reflectances were calculated at 4 nm wavelength intervals and reported as averages over the 400 to 700 nm wavelength range.

The single sheet gain is tested in the vertical orientation (or the orientation perpendicular to the front of the diffuser box used in the E.T. Tester). In a horizontal or intersecting sheet arrangement, the bottom sheet of the film stack is perpendicular to the front side of the diffuser box and the top sheet is horizontal or parallel thereto.

Table 1 below shows the test results of the optical film. The gain of the brightness | luminance obtained from these films was surprisingly high, when using the monomer and resin composition of this invention.

Claims (25)

A polymerized product comprising a reaction product of a polymerizable resin composition comprising 10 to 100 wt% of at least one biphenyl di (meth) acrylate monomer that is liquid at 25 ° C. comprising two aromatic rings linked by a CC bond Optical film having a microstructured surface. 10 to 100 percent by weight of at least one biphenyl di (meth) acrylate monomer comprising two aromatic rings linked by CC bonds and comprising at least one (meth) acrylate substituent in the ortho or meta position An optical film having a polymerized microstructured surface comprising a reaction product of a polymerizable resin composition. 3. The biphenyl di (meth) acrylate monomer of claim 1, wherein the biphenyl di (meth) acrylate monomer is H ₂ C = (R 1) C (O)---Ar-Ar---(O) C (R 1) = CH ₂ Wherein each Ar group is independently phenyl or naphthyl and R 1 is H or methyl. The optical film of claim 1, wherein each (meth) acrylate group is bonded to an aromatic ring group at an ortho or meta position. The optical film of claim 1, wherein each (meth) acrylate group is bonded to an aromatic ring group at the ortho position. The optical film according to any one of claims 1 to 3, wherein each (meth) acrylate group is independently bonded to an aromatic ring by a bonding group having a molecular weight of less than 1200 g / mol. The optical film of claim 6, wherein the linking group is an alkoxy group. The biphenyl di (meth) acrylate monomer of claim 3, wherein the biphenyl di (meth) acrylate monomer is

Wherein each R 1 is independently H or methyl; Each R 2 is independently Br; m ranges from 0 to 4; Each Q is independently O or S; n ranges from 0 to 10; L is a C2 to C12 alkyl group optionally substituted with one or more hydroxyl groups; Z is an aromatic ring; t is independently 0 or 1; -Q [LO] n C (O) C (R1) = CH ₂ group wherein at least one of the groups is substituted in ortho or meta position). The optical film of claim 8, wherein Q is O. 10. The optical film of claim 8, wherein n is 0, 1 or 2. 10. The optical film of claim 8, wherein L is C2 or C3. The optical film of claim 8, wherein L is hydroxyl substituted C2 or C3. The optical film of claim 8, wherein each -Q [LO] n C (O) C (R 1) = CH ₂ is substituted at the ortho or meta position. The optical film of claim 8, wherein each -Q [LO] n C (O) C (R 1) = CH ₂ is substituted at the ortho position. The optical film of claim 8, wherein Z is fused. The optical film of claim 8, wherein the biphenyl di (meth) acrylate monomer is non-halogenated. The optical film of claim 8, wherein the monomer has a general structure of the following formula.

The optical film of claim 8, wherein the monomer has a general structure of the following formula.

The optical film of claim 1, wherein the monomer has a refractive index of at least 1.55. 25% to 75% by weight of one or more biphenyl di (meth) acrylate monomers having a (meth) acrylate substituent in the ortho or meta position, and An optical film having a polymerized microstructured surface comprising a reaction product of a polymerizable resin composition comprising from 25% to 75% by weight of at least one bisphenol A di (meth) acrylate monomer. The optical film according to any one of claims 1 to 20, wherein the polymerizable resin composition is non-halogenated. The optical film according to any one of claims 1 to 20, wherein the polymerizable resin is free of inorganic nanoparticles. The optical film of claim 1, wherein the polymerizable resin comprises at least 10 wt% surface modified inorganic nanoparticles. The optical film of claim 23, wherein the inorganic nanoparticles comprise zirconia. 25. The optical film of any one of claims 1 to 24, wherein the single sheet gain is a brightness enhancement film of at least 1.59.