JP2009223012A - Projection screen and projection system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a projection screen and a projection system, can obtain a satisfactory contrast. <P>SOLUTION: This projection screen 100 is provided with a support base material 150, a circular-polarized light separating layer 110, and a phase difference layer in this order, and is provided further with a light-dispersible adhesive layer 125 containing a light dispersant, in particular, a gradient refractive index particle, between the circular-polarized light separating layer and the phase difference layer. This projection system is provided with the projection screen and an image projector. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a projection screen and a projection system, and more particularly to a reflection type projection screen and a projection system including the projection screen.

  A projection screen for projecting video light from an image projector to display an image is required to reflect a large amount of video light and to reduce the reflection of other environmental light in order to obtain a good contrast.

  Therefore, for example, Patent Document 1 proposes to provide a reflective polarization element in a part of a layer constituting the projection screen. In other words, a layer that reflects only predetermined polarized light is provided on the screen, thereby selectively reflecting the polarized light from the liquid crystal projector, while only a part of the predetermined polarized light is unpolarized ambient light. The contrast of the image on the screen is improved by being reflected. However, such specular reflection by the reflective polarizing element has a problem that it is difficult to obtain the scattering property of the reflected light necessary for the projection screen.

  In order to obtain the scattering property of the reflected light, for example, Patent Document 2 proposes that the cholesteric liquid crystal structure of the layer having the cholesteric liquid crystal structure, which is a reflective polarizing element, is non-uniform. However, in the reflective polarizing layer having such a non-uniform structure, the ratio of selectively reflecting the image light decreases, and it is difficult to obtain good contrast after all.

Special Table 2002-540445 Japanese Patent Laid-Open No. 2005-3823

  The present invention has been made in view of the above-described conventional problems, and an object thereof is to provide a projection screen and a projection system capable of obtaining a good contrast.

As a result of studying to solve the above problem, the present inventors have found that the above problem can be solved by sticking a retardation layer to a layer that reflects predetermined polarized light through a light-diffusing adhesive layer. The headline and the present invention were completed.
That is, the present invention provides the following [1] to [4].
[1] A projection screen comprising a supporting substrate, a circularly polarized light separating layer provided on the supporting substrate, and a retardation layer provided on the circularly polarized light separating layer, wherein the circularly polarized light separating layer and A projection screen, further comprising a light diffusing adhesive layer containing a light diffusing agent between the retardation layer.
[2] The projection screen, wherein the light diffusing agent is a gradient refractive index particle.
[3] The retardation layer is an optically anisotropic element in which an in-plane retardation Re is substantially a quarter of transmitted light and a thickness direction retardation Rth is less than 0 nm. Said projection screen.
[4] A projection system comprising the projection screen and an image projector.

  The projection screen of the present invention and the projection system of the present invention provided with the projection screen have a predetermined light diffusive pressure-sensitive adhesive layer, so that the circularly polarized light separation layer has a uniform specular reflection, but has good diffusibility as a screen. Can be obtained, a decrease in contrast due to ambient light is suppressed, and an image with good contrast can be displayed.

The projection screen of the present invention includes a support base, a circularly polarized light separating layer, and a retardation layer in this order, and a light diffusing adhesive containing a light diffusing agent between the circularly polarized light separating layer and the retardation layer. Further comprising a layer.
FIG. 1 is a sectional view showing an example of the projection screen of the present invention. In FIG. 1, the projection screen 100 includes a support base 150, a circularly polarized light separating layer 110, a retardation layer 130, and a light diffusive adhesive layer 120 between the circularly polarized light separating layer 110 and the retardation layer 130. The diffusive adhesive layer 120 contains an adhesive resin 121 and gradient refractive index particles 125 as a light diffusing agent dispersed therein.

  The projection screen 100 uses the surface 131 on the retardation layer 130 side as a projection surface. When image light that is linearly polarized light emitted from the liquid crystal projector is projected onto the projection surface 131, the image light passes through the retardation layer. At this time, linearly polarized light can be converted to circularly polarized light by appropriately designing the retardation layer.

  The image light converted into the circularly polarized light is reflected by the circularly polarized light separating layer 110 and is emitted to an observer who observes the projection plane. Here, when the image light is specularly reflected in the circularly polarized light separating layer, the image cannot be observed well and the screen does not perform a good function. However, the image light is diffused before and after being reflected by the circularly polarized light separating layer 110. By being diffused by the adhesive layer 120, desired reflected light can be obtained by the circularly polarized light separation layer, specular reflection is suppressed, images can be observed satisfactorily on the projection surface, and images with high contrast can be projected. It becomes possible.

  On the other hand, since the ambient light, which is light other than the image light, is non-polarized light, only a part of the light is reflected by the circularly polarized light separation layer 110, and the rest is transmitted and reaches the support base material 150 to be absorbed. Therefore, reflection of ambient light is suppressed, and a high contrast image can be projected.

  Hereinafter, each layer which comprises a projection screen is demonstrated sequentially.

(Circularly polarized light separating layer)
The circularly polarized light separating layer used in the present invention is an element having a property of selectively transmitting only predetermined circularly polarized light and reflecting other light. Specifically, an element having a resin layer having cholesteric regularity (hereinafter sometimes simply referred to as “cholesteric resin layer”) can be used. The cholesteric resin layer is preferably a non-liquid crystalline layer. More specifically, a resin layer in which molecular orientation having cholesteric regularity is fixed is preferable. Preferable examples of the cholesteric resin layer include those obtained by curing a cholesteric liquid crystal composition containing a rod-like liquid crystal compound.

(Cholesteric liquid crystal composition)
Preferred examples of the cholesteric liquid crystal composition used in the present invention include those containing a rod-like liquid crystal compound having Δn of 0.18 or more and having at least two or more reactive groups in one molecule.

Examples of the rod-like liquid crystalline compound include a compound represented by (Formula 2).
R ³ -C ³ -D ³ -C ⁵ -M C ⁶ -D ⁴ -C ⁴ -R ⁴ (Formula 2)
(Wherein R ³ and R ⁴ are reactive groups, each independently (meth) acryl group, (thio) epoxy group, oxetane group, thietanyl group, aziridinyl group, pyrrole group, vinyl group, allyl group, D ³ and D ⁴ each represent a group selected from the group consisting of a fumarate group, a cinnamoyl group, an oxazoline group, a mercapto group, an iso (thio) cyanate group, an amino group, a hydroxyl group, a carboxyl group, and an alkoxysilyl group. A group selected from the group consisting of a bond, a linear or branched alkyl group having 1 to 20 carbon atoms, and a linear or branched alkylene oxide group having 1 to 20 carbon atoms; C ^{3 to} C ⁶ are a single bond, —O—, —S—, —S—S—, —CO—, —CS—, —OCO—, —CH ₂ —, —OCH ₂ —, —C═. N—N═C—, —NHCO— _{, -OCOO -, - CH 2 COO-} , and .M represents a group selected from the group consisting of -CH ₂ OCO- represents a mesogenic group, specifically, have a unsubstituted or substituted group Azomethines, azoxys, phenyls, biphenyls, terphenyls, naphthalenes, anthracenes, benzoic acid esters, cyclohexanecarboxylic acid phenyl esters, cyanophenylcyclohexanes, cyano-substituted phenylpyrimidines, alkoxy-substituted Two to four skeletons selected from the group of phenylpyrimidines, phenyldioxanes, tolanes, and alkenylcyclohexylbenzonitriles are converted to —O—, —S—, —S—S—, —CO—, —CS. -, - OCO -, - CH 2 -, - OCH 2 -, - C = N-N = C -, - NHCO -, - OCOO -, - C ₂ COO-, and is formed are joined by a linking group of -CH ₂ OCO-, and the like.)

Examples of the substituent that the mesogenic group M may have include a halogen atom, an optionally substituted alkyl group having 1 to 10 carbon atoms, a cyano group, a nitro group, —O—R ⁵ , —O—C. (═O) —R ⁵ , —C (═O) —O—R ⁵ , —O—C (═O) —O—R ⁵ , —NR ⁵ —C (═O) —R ⁵ , —C ( ═O) —NR ⁵ R ⁷ or —O—C (═O) —NR ⁵ R ⁵ . Wherein, R ⁵ and ^{R 7} represent a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, when it is alkyl group, and the alkyl group, -O -, - S -, - O-C (= O) —, —C (═O) —O—, —O—C (═O) —O—, —NR ⁶ —C (═O) —, —C (═O) —NR ⁶ —, —NR ^6- or -C (= O)-may be present (except when two or more of -O- and -S- are present adjacent to each other). Wherein, R ⁶ represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms. Examples of the substituent in the “optionally substituted alkyl group having 1 to 10 carbon atoms” include a halogen atom, a hydroxyl group, a carboxyl group, a cyano group, an amino group, and an alkoxy group having 1 to 6 carbon atoms. Group, alkoxyalkoxy group having 2 to 8 carbon atoms, alkoxyalkoxyalkoxy group having 3 to 15 carbon atoms, alkoxycarbonyl group having 2 to 7 carbon atoms, alkylcarbonyloxy having 2 to 7 carbon atoms Group, an alkoxycarbonyloxy group having 2 to 7 carbon atoms, and the like.

In the present invention, the rod-like liquid crystalline compound preferably has an asymmetric structure. Here, the asymmetric structure is a structure in which R ³ -C ³ -D ³ -C ⁵ -and -C ⁶ -D ⁴ -C ⁴ -R ⁴ are different in the general formula (2) with the mesogenic group M as the center. Say. By using a rod-like liquid crystal compound having an asymmetric structure, alignment uniformity can be further improved.

  In the present invention, the rod-like liquid crystalline compound has a Δn value of preferably 0.18 or more, more preferably 0.22 or more. When a compound having an Δn value of 0.30 or more is used, the absorption edge on the long wavelength side of the ultraviolet absorption spectrum may extend to the visible range, but desired optical performance even when the absorption edge of the spectrum extends to the visible range. It can be used as long as it does not adversely affect By having such a high Δn value, a circularly polarized light separation layer having high optical performance (for example, circularly polarized light separation characteristics) can be provided.

  In the present invention, the rod-like liquid crystal compound preferably has at least two reactive groups in one molecule. Specific examples of the reactive group include an epoxy group, a thioepoxy group, an oxetane group, a thietanyl group, an aziridinyl group, a pyrrole group, a fumarate group, a cinnamoyl group, an isocyanate group, an isothiocyanate group, an amino group, a hydroxyl group, and a carboxyl group. , Alkoxysilyl groups, oxazoline groups, mercapto groups, vinyl groups, allyl groups, methacryl groups, and acrylic groups. By having these reactive groups, a stable cured product can be obtained when the cholesteric liquid crystal composition used in the present invention is cured. When a compound having one or less reactive group in one molecule is used, when the cholesteric liquid crystal composition is cured, a crosslinked cured product cannot be obtained, so that a film strength that can withstand practical use cannot be obtained. Even when a cross-linking agent described later is used, the film strength is insufficient and practical use is difficult. The film strength that can be practically used is HB or more, preferably H or more, in pencil hardness (JIS K5400). If the film strength is lower than HB, the film is easily scratched and lacks handling properties. The upper limit of preferable pencil hardness is not particularly limited as long as it does not adversely affect the optical performance and durability test.

The cholesteric liquid crystal composition used in the present invention preferably contains a compound represented by the following general formula (1) in addition to the rod-like liquid crystal compound.
R ¹ -A ¹ -BA ² -R ² (1)
Wherein R ¹ and R ² are each independently a linear or branched alkyl group having 1 to 20 carbon atoms, which may be unsubstituted or substituted with one or more halogen atoms. A linear or branched chain group having 1 to 20 carbon atoms, an unsubstituted or optionally substituted alkylene oxide group having one or more halogen atoms; a hydrogen atom; an alkyl group having 1 to 2 carbon atoms; Or a halogen atom, a hydroxyl group, a carboxyl group, a (meth) acryl group, an epoxy group, a mercapto group, an isocyanate group, an amino group, and a cyano group, which may be bonded to an alkylene oxide group. Group,
A ¹ and A ² are each independently unsubstituted or substituted with one or more halogen atoms, hydroxyl groups, carboxyl groups, cyano groups, amino groups, alkyl groups having 1 to 10 carbon atoms, or halogenated alkyl groups. 1,4-phenylene group, 1,4-cyclohexylene group, 1,4-cyclohexenyl group, 4,4′-biphenylene group, 4,4′-bicyclohexylene group, and 2, Represents a group selected from the group consisting of: 6-naphthylene group;
B represents a single bond, —O—, —S—, —S—S—, —CO—, —CS—, —OCO—, —CH ₂ —, —OCH ₂ —, —C═N—N═C—. , -NHCO -, - OCOO -, - CH 2 COO-, and is selected from the group consisting of -CH ₂ OCO-. )

In General Formula (1), R ¹ and R ² are each independently a linear or branched alkyl group having 1 to 20 carbon atoms, or a linear or branched chain having 1 to 20 carbon atoms. And a group selected from the group consisting of a hydrogen atom, a halogen atom, a hydroxyl group, a carboxyl group, a (meth) acryl group, an epoxy group, a mercapto group, an isocyanate group, an amino group, and a cyano group. Here, (meth) acryl means acryl and methacryl.

  The alkyl group and alkylene oxide group may be unsubstituted or substituted with one or more halogen atoms. The halogen atom, hydroxyl group, carboxyl group, (meth) acryl group, epoxy group, mercapto group, isocyanate group, amino group, and cyano group are bonded to an alkyl group having 1 to 2 carbon atoms or an alkylene oxide group. May be.

Preferable examples of R ¹ and R ² include a halogen atom, hydroxyl group, carboxyl group, (meth) acryl group, epoxy group, mercapto group, isocyanate group, amino group, and cyano group.

Moreover, it is preferable that at least one of R ¹ and R ² is a reactive group. By having a reactive group as R ¹ and / or R ² , the compound represented by the general formula (1) is fixed in the liquid crystal layer at the time of curing, and a stronger film can be formed. Here, examples of the reactive group include a carboxyl group, a (meth) acryl group, an epoxy group, a mercapto group, an isocyanate group, and an amino group.

In the general formula (1), A ¹ and A ² are each independently 1,4-phenylene group, 1,4-cyclohexylene group, 1,4-cyclohexenyl group, 4,4′-biphenylene group, 4, It represents a group selected from the group consisting of a 4′-bicyclohexylene group and a 2,6-naphthylene group. The 1,4-phenylene group, 1,4-cyclohexylene group, 1,4-cyclohexenyl group, 4,4′-biphenylene group, 4,4′-bicyclohexylene group, and 2,6-naphthylene group are , It may be unsubstituted or substituted with one or more halogen atoms, hydroxyl groups, carboxyl groups, cyano groups, amino groups, alkyl groups having 1 to 10 carbon atoms, or halogenated alkyl groups. In each of A ¹ and A ² , when two or more substituents are present, they may be the same or different.

Particularly preferred examples of A ¹ and A ² include groups selected from the group consisting of 1,4-phenylene group, 4,4′-biphenylene group, and 2,6-naphthylene group. These aromatic ring skeletons are relatively rigid as compared with the alicyclic skeletons, have high affinity with the mesogens of the rod-like liquid crystalline compounds contained in the liquid crystal composition of the present invention, and higher alignment uniformity ability.

In the general formula (1), B represents a single bond, —O—, —S—, —S—S—, —CO—, —CS—, —OCO—, —CH ₂ —, —OCH ₂ —, —C. = N-N = C -, - NHCO -, - OCOO -, - CH 2 COO-, and is selected from the group consisting of -CH ₂ OCO-.

  Particularly preferable examples of B include a single bond, —OCO—, and —C═N—N═C—.

  As for the compound of General formula (1), it is preferable that at least 1 type has liquid crystallinity, and it is preferable to have chirality. The cholesteric liquid crystal composition used in the present invention preferably contains a mixture of a plurality of optical isomers as the compound of the general formula (1). For example, a mixture of plural kinds of enantiomers and / or diastereomers can be contained. At least one of the compounds of the general formula (1) preferably has a melting point in the range of 50 ° C to 150 ° C.

  When the compound of the general formula (1) has liquid crystallinity, a high Δn is preferable. By containing a high Δn liquid crystal, Δn as a cholesteric liquid crystal composition can be improved, and a broadband circularly polarized light separating layer can be produced. At least one Δn of the compound of the general formula (1) is preferably 0.18 or more, more preferably 0.22 or more.

  Specific examples of particularly preferred compounds of the general formula (1) include the following compounds (A1) to (A3) and (A5) to (A10):

  In the compound (A3), “*” represents a chiral center.

  In the cholesteric liquid crystal composition used in the present invention, the weight ratio of (total weight of compound of general formula (1)) / (total weight of rod-like liquid crystal compound) is 0.05 to 1, preferably 0.1 to 0. .65, more preferably 0.15 to 0.45. When the weight ratio is less than 0.05, the alignment uniformity may be insufficient. On the other hand, when the weight ratio is more than 1, the alignment uniformity decreases, the stability of the liquid crystal phase decreases, and the liquid crystal composition As a result, the desired optical performance (for example, circularly polarized light separation characteristics) may not be obtained. The total weight indicates the weight when one kind is used and the total weight when one or more kinds are used.

  In the cholesteric liquid crystal composition used in the present invention, the compound of the general formula (1) preferably has a molecular weight of less than 600, and the rod-like liquid crystal compound has a molecular weight of 600 or more. When the molecular weight of the compound of the general formula (1) is less than 600, the rod-like liquid crystal compound having a molecular weight larger than that can enter the gap, and the alignment uniformity can be improved.

The cholesteric liquid crystal composition used in the present invention can optionally contain a cross-linking agent in order to improve the film strength and durability after curing. As the cross-linking agent, it reacts simultaneously when the liquid crystal layer coated with the liquid crystal composition is cured, or heat treatment is performed after curing to accelerate the reaction, or the reaction proceeds spontaneously by moisture to increase the crosslinking density of the liquid crystal layer. Those that can be enhanced and that do not deteriorate the alignment uniformity can be appropriately selected and used, and those that are cured by ultraviolet rays, heat, moisture, etc. can be suitably used. Specific examples of the crosslinking agent include, for example, trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol hexa (meth) acrylate, 2- (2-vinyl Polyfunctional acrylate compounds such as loxyethoxy) ethyl acrylate; epoxy compounds such as glycidyl (meth) acrylate, ethylene glycol diglycidyl ether, glycerin triglycidyl ether, pentaerythritol tetraglycidyl ether; 2,2-bishydroxymethylbutanol-tris [ 3- (1-aziridinyl) propionate], 4,4-bis (ethyleneiminocarbonylamino) diphenylmethane, trimethylolpropane-tri-β-aziridinini Aziridine compounds such as lupropionate; Isocyanurate type isocyanates derived from hexamethylene diisocyanate, hexamethylene diisocyanate, isocyanurate type isocyanates, biuret type isocyanates, adduct type isocyanates; polyoxazoline compounds having an oxazoline group in the side chain; vinyltrimethoxysilane; N- (2-aminoethyl) 3-aminopropyltrimethoxysilane, 3-aminopropyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3- (meth) acryloxypropyltrimethoxysilane, N- (1 , 3-dimethylbutylidene) -3- (triethoxysilyl) -1-propanamine and the like alkoxysilane compounds. Moreover, a well-known catalyst can be used according to the reactivity of this crosslinking agent, and productivity can be improved in addition to an improvement in film strength and durability.
The blending ratio of the crosslinking agent is preferably 0.1 to 15% by weight in a cured film obtained by curing the cholesteric liquid crystal composition. When the blending ratio of the crosslinking agent is less than 0.1% by weight, the effect of improving the crosslinking density cannot be obtained. Conversely, when the blending ratio is more than 15% by weight, the stability of the liquid crystal layer is lowered, which is not preferable.

The cholesteric liquid crystal composition used in the present invention can optionally contain a photoinitiator. As the photoinitiator, known compounds that generate radicals or acids by ultraviolet rays or visible rays can be used. Specifically, benzoin, benzylmethyl ketal, benzophenone, biacetyl, acetophenone, Michler's ketone, benzyl, benzylisobutyl ether, tetramethylthiuram mono (di) sulfide, 2,2-azobisisobutyronitrile, 2,2-azobis -2,4-dimethylvaleronitrile, benzoyl peroxide, di-tert-butyl peroxide, 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methyl-1-phenyl-propan-1-one, 1- (4 -Isopropylphenyl) -2-hydroxy-2-methylpropan-1-one, thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, 2,4-diethylthioxanthone, methylbenzoyl formate, 2,2-dieto Cyacetophenone, β-ionone, β-bromostyrene, diazoaminobenzene, α-amylcinnac aldehyde, p-dimethylaminoacetophenone, p-dimethylaminopropiophenone, 2-chlorobenzophenone, pp′-dichlorobenzophenone, pp ′ -Bisdiethylaminobenzophenone, benzoin ethyl ether, benzoin isopropyl ether, benzoin n-propyl ether, benzoin n-butyl ether, diphenyl sulfide, bis (2,6-methoxybenzoyl) -2,4,4-trimethyl-pentylphosphine oxide, 2,4,6-trimethylbenzoyldiphenyl-phosphine oxide, bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide, 2-methyl-1 [ 4- (methylthio) phenyl] -2-morpholinopropan-1-one, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butan-1-one, anthracenebenzophenone, α-chloroanthraquinone , Diphenyl disulfide, hexachlorobutadiene, pentachlorobutadiene, octachlorobutene, 1-chloromethylnaphthalene, 1,2-octanedione, 1- [4- (phenylthio) -2- (o-benzoyloxime)] and 1- [9-Ethyl-6- (2-methylbenzoyl) -9H-carbazol-3-yl] ethanone 1- (o-acetyloxime), (4-methylphenyl) [4- (2-methylpropyl) phenyl] iodonium Hexafluorophosphate, 3-methyl-2-butynyltetramethylsulfonate Arm hexafluoroantimonate, diphenyl - (p-phenylthiophenyl) sulfonium hexafluoroantimonate, and the like. In addition, two or more compounds can be mixed depending on the desired physical properties, and if necessary, a known photosensitizer or a tertiary amine compound as a polymerization accelerator is added to control curability. You can also.
The blending ratio of the photoinitiator is preferably 0.03 to 7% by weight in the cholesteric liquid crystal composition. When the blending amount of the photoinitiator is less than 0.03% by weight, the degree of polymerization is lowered and the film strength may be lowered. On the other hand, if it is more than 7% by weight, the alignment of the liquid crystal is inhibited and the liquid crystal phase may become unstable.

  The cholesteric liquid crystal composition used in the present invention can optionally contain a surfactant. As the surfactant, those not inhibiting the orientation can be appropriately selected and used. As the surfactant, specifically, a nonionic surfactant containing siloxane or fluorinated alkyl group in the hydrophobic group portion can be preferably used, and an oligomer having two or more hydrophobic group portions in one molecule. Is particularly preferred. These surfactants are OMNOVA PolyFox PF-151N, PF-636, PF-6320, PF-656, PF-6520, PF-3320, PF-651, PF-652, Neos's Fantgent FTX- 209F, FTX-208G, FTX-204D, Seimi Chemical's Surflon KH-40, and the like can be used. The blending ratio of the surfactant is preferably 0.05% by weight to 3% by weight in the cured film obtained by curing the cholesteric liquid crystal composition. When the blending ratio of the surfactant is less than 0.05% by weight, the orientation regulating force at the air interface is lowered and an orientation defect may occur, which is not preferable. On the other hand, when the amount is more than 3% by weight, it is not preferable because an excessive surfactant may enter between liquid crystal molecules and lower the alignment uniformity.

  The cholesteric liquid crystal composition used in the present invention can further contain other optional components as necessary. Examples of the other optional components include a chiral agent, a solvent, a polymerization inhibitor for improving pot life, an antioxidant for improving durability, an ultraviolet absorber, and a light stabilizer. These optional components can be added as long as the desired optical performance is not deteriorated.

  The method for preparing the cholesteric liquid crystal composition used in the present invention is not particularly limited, and the cholesteric liquid crystal composition can be produced by mixing the above essential components and optional components.

(Preparation of circularly polarized light separating layer)
The method for preparing the circularly polarized light separating layer used in the present invention is not particularly limited, but a liquid crystal layer is obtained by applying the cholesteric liquid crystal composition to a substrate, and then by at least one light irradiation and / or heating treatment. It can be prepared by curing.
Here, as the base material, a support base material constituting the projection screen of the present invention can be used, and a cholesteric resin layer can be directly formed thereon to form a circularly polarized light separation layer. Alternatively, a resin base material different from the support base material may be used, and a cholesteric resin layer may be formed thereon to form a circularly polarized light separation layer, which may be attached to the support base material.

  When using a base material different from the supporting base material as the base material, an opaque base material can be used, but a transparent resin base material can also be used from the viewpoint of convenience of the light irradiation process described later. The transparent resin substrate is not particularly limited, and a substrate having a thickness of 1 mm and a total light transmittance of 80% or more can be used.

  Specific examples of the material constituting the base material include alicyclic olefin polymers, chain olefin polymers such as polyethylene and polypropylene, triacetyl cellulose, polyvinyl alcohol, polyimide, polyarylate, polyester, polycarbonate, polysulfone, and polyether. Examples thereof include a single layer or laminated film made of a synthetic resin such as sulfone, modified acrylic polymer, epoxy resin, polystyrene, and acrylic resin. Among these, an alicyclic olefin polymer or a chain olefin polymer is preferable, and an alicyclic olefin polymer is particularly preferable from the viewpoint of transparency, low hygroscopicity, dimensional stability, lightness, and the like.

  In forming the circularly polarized light separating layer, an alignment film can be provided on the substrate as necessary. By having the alignment film, the cholesteric liquid crystal composition applied thereon can be aligned in a desired direction. The alignment film is subjected to a corona discharge treatment, if necessary, on the substrate surface, followed by cellulose, silane coupling agent, polyimide, polyamide, polyvinyl alcohol, epoxy acrylate, silanol oligomer, polyacrylonitrile, phenol resin, poly A solution in which oxazole, cyclized polyisoprene or the like is dissolved in water or a solvent is applied using a known method such as reverse gravure coating, direct gravure coating, die coating, bar coating, and the like, and then dried. It can be formed by subjecting to rubbing treatment. The thickness of the alignment film may be any film thickness that provides the desired alignment uniformity of the liquid crystal layer, and is preferably 0.001 to 5 μm, and more preferably 0.01 to 2 μm.

  Application | coating of the liquid-crystal composition to a base material can be performed by well-known methods, such as reverse gravure coating, direct gravure coating, die coating, and bar coating. The thickness of the coating layer of the liquid crystal composition can be appropriately adjusted so that a desired liquid crystal layer dry film thickness described later can be obtained.

  Before curing the coating layer obtained by the coating, an orientation treatment can be performed as necessary. The alignment treatment can be performed, for example, by heating the coating layer at 50 to 150 ° C. for 0.5 to 10 minutes. By performing the alignment treatment, the cholesteric liquid crystal layer can be aligned well.

After performing an alignment treatment as necessary, the cholesteric liquid crystal composition is cured to obtain a circularly polarized light separation layer having a cured layer of the cholesteric liquid crystal composition (hereinafter sometimes simply referred to as “cured liquid crystal layer”). be able to. The curing step can be performed by a combination of one or more light irradiations and a heating treatment. Specifically, the heating condition is, for example, a temperature of 40 to 200 ° C., preferably 50 to 200 ° C., more preferably 50 to 140 ° C., and a time of 1 second to 3 minutes, preferably 5 to 120 seconds. it can. The light used for light irradiation in the present invention includes not only visible light but also ultraviolet rays and other electromagnetic waves. Specifically, the light irradiation can be performed by, for example, irradiating light having a wavelength of 200 to 500 nm for 0.01 second to 3 minutes. Further, for example, a weakly irradiated ultraviolet ray of 0.01 to 50 mJ / cm ² and heating may be alternately repeated a plurality of times to form a circularly polarized light separating layer having a wide reflection band. After extending the reflection band by the above-mentioned weak ultraviolet irradiation, etc., a relatively strong ultraviolet ray of 50 to 10,000 mJ / cm ² is irradiated to completely polymerize the liquid crystalline compound to form a cured liquid crystal layer. it can. The expansion of the reflection band and the irradiation with strong ultraviolet rays may be performed in the air, or a part or all of the process may be performed in an atmosphere in which the oxygen concentration is controlled (for example, in a nitrogen atmosphere). .

  In the present invention, the step of applying and curing the cholesteric liquid crystal composition on the substrate is not limited to one time, and two or more cured liquid crystal layers can be formed by repeating the application and curing a plurality of times. However, in the present invention, a cured liquid crystal layer having a thickness of 5 μm or more that contains a well-oriented rod-like liquid crystalline compound having a Δn of 0.18 or more can be easily formed even by applying and curing the cholesteric liquid crystal composition only once. can do.

  In the circularly polarized light separating layer used in the present invention, the dry thickness of the cured liquid crystal layer can be preferably 3.0 μm to 10.0 μm, more preferably 3.5 to 8 μm. If the dried film thickness of the cured liquid crystal layer is less than 3.0 μm, the reflectivity decreases, and conversely if it is thicker than 10.0 μm, the cured liquid crystal layer is colored when observed from an oblique direction, Each is not preferred. The dry film thickness refers to the total film thickness of each layer when the cured liquid crystal layer is two or more layers, and the film thickness when the cured liquid crystal layer is one layer.

(Supporting substrate)
The supporting substrate is for supporting other layers such as a circularly polarized light separating layer. Examples of the material constituting the supporting base material include the same materials as the base material such as the transparent resin base material used in the preparation of the above-mentioned circularly polarized light separating layer, and other plastic films, metals, paper materials, cloths, etc. It can be formed using materials such as materials and glass.

  The support substrate preferably includes a light absorption layer that absorbs light in the visible light range.

Specifically, for example, the support substrate can be formed using a plastic film kneaded with a black pigment (for example, a black PET film kneaded with carbon).
Or it can also be set as the support base material which has the laminated structure which apply | coated the black pigment on the surfaces, such as a plastic film.
By adopting such a configuration, it is possible to prevent light that is not preferably reflected, such as ambient light, from being reflected after being transmitted through the circularly polarized light separating layer and then passing through the circularly polarized light separating layer again. it can.

  The thickness of the support substrate is preferably 15 to 300 μm, more preferably 25 to 100 μm, considering that it can be wound up. On the other hand, when the support base material does not require flexibility as in the case of being used as a panel, the thickness can be increased without limitation.

  Moreover, when using a plastic other than the same material as the transparent resin substrate as the material for the support substrate, the plastic includes a polycarbonate polymer, a polyester polymer such as polyethylene terephthalate, a polyimide polymer, Polysulfone polymers, polyethersulfone polymers, polystyrene polymers, polyolefin polymers such as polyethylene and polypropylene, polyvinyl alcohol polymers, cellulose acetate polymers, polyvinyl chloride polymers, polyacrylate polymers Polymers such as polymers and thermoplastic polymers such as polymethyl methacrylate polymers can be used.

(Retardation layer)
The projection screen of the present invention includes a retardation layer in addition to the circularly polarized light separating layer and the support substrate.

  As the retardation layer used in the present invention, (i) a film-like polymer stretched or (ii) a liquid crystal material applied on a transparent resin substrate, oriented and cured is used. Can do. In the case of using the retardation layer (ii), a liquid crystalline material is applied on an appropriate base material, oriented, cured, and the retardation layer obtained by integrating with the circularly polarized light separating layer is selectively reflected. An element can be used, or an alignment film is provided on the circularly polarized light separating layer as necessary, and various alignment treatments are performed, and a liquid crystalline material is applied thereon, aligned, and cured. Thus, a retardation layer integrated with the circularly polarized light separating layer can be provided.

Preferred examples of the retardation film used in the present invention include the optically anisotropic elements described below.
The optically anisotropic element used in the present invention is an element whose retardation Re in the front direction (hereinafter sometimes abbreviated as “Re”) is approximately ¼ wavelength of transmitted light. Here, the wavelength range of the transmitted light can be set to a desired range required to be displayed by the projection screen of the present invention, and specifically, for example, 400 nm to 700 nm. Further, the retardation Re in the front direction is approximately ¼ wavelength of transmitted light, and the Re value is ± 65 nm from the ¼ value of the center value in the center value of the wavelength range of transmitted light, preferably It means ± 30 nm, more preferably ± 10 nm.

The optically anisotropic element desirably has a thickness direction retardation Rth (hereinafter sometimes abbreviated as “Rth”) of less than 0 nm. The value of retardation Rth in the thickness direction is preferably −30 nm to −1000 nm, more preferably −50 nm to −300 nm, in the central value of the wavelength range of transmitted light. By adopting such an optically anisotropic element having Re value and Rth, even when the screen is observed not only in the front direction but also from an oblique direction, a uniform display can be obtained.
Here, the retardation Re in the front direction is represented by the formula I: Re = (nx−ny) × d (where nx is a direction perpendicular to the thickness direction (front direction) and gives the maximum refractive index). Ny represents a refractive index in a direction perpendicular to the thickness direction (in-plane direction) and perpendicular to nx, and d represents a film thickness). The direction retardation Rth is expressed by the formula II: Rth = {(nx + ny) / 2−nz} × d (where nx is a direction perpendicular to the thickness direction (in-plane direction) and gives the maximum refractive index) Ny is the refractive index in the direction perpendicular to the thickness direction (in-plane direction) and orthogonal to nx, nz is the refractive index in the thickness direction, and d is the film thickness. ).
In addition, the retardation Re in the front direction and the retardation Rth in the thickness direction are measured using a commercially available phase difference measuring apparatus, and the optically anisotropic elements are spaced 100 mm apart in the longitudinal direction and the width direction (longitudinal or lateral length). If the distance is less than 200 mm, three points are specified at equal intervals in that direction), and measurement is performed in a lattice point shape over the entire surface, and the average value is obtained.

  Although the material which comprises the said optically anisotropic element is not specifically limited, What has the layer which consists of a styrene resin can be used preferably. Here, the styrene-based resin is a polymer resin having a styrene structure as a part or all of the repeating unit, and polystyrene, styrene, α-methylstyrene, o-methylstyrene, p-methylstyrene, p-chlorostyrene. , Styrene monomers such as p-nitrostyrene, p-aminostyrene, p-carboxystyrene, p-phenylstyrene, ethylene, propylene, butadiene, isoprene, acrylonitrile, methacrylonitrile, α-chloroacrylonitrile, acrylic acid Examples thereof include copolymers with other monomers such as methyl, methyl methacrylate, ethyl acrylate, ethyl methacrylate, acrylic acid, methacrylic acid, maleic anhydride, and vinyl acetate. Among these, polystyrene or a copolymer of styrene and maleic anhydride can be suitably used.

  The molecular weight of the styrenic resin used for the optically anisotropic element is appropriately selected according to the purpose of use, but is the weight average molecular weight (Mw) of polyisoprene measured by gel permeation chromatography using cyclohexane as a solvent. Usually, 10,000 to 300,000, preferably 15,000 to 250,000, and more preferably 20,000 to 200,000.

  The optically anisotropic element preferably has a laminated structure of a layer made of the styrenic resin and a layer containing another thermoplastic resin. By having the laminated structure, it is possible to provide an element that has both the optical characteristics of the styrene resin and the mechanical strength of other thermoplastic resins. Other thermoplastic resins include alicyclic olefin polymers, methacrylic resins, polycarbonates, acrylic ester-vinyl aromatic compound copolymer resins, methacrylic ester-vinyl aromatic compound copolymer resins, polyethersulfone, etc. Can be mentioned. Among these, a resin having an alicyclic structure or a methacrylic resin can be preferably used.

  The alicyclic olefin polymer is an amorphous olefin polymer having a cycloalkane structure or a cycloalkene structure in the main chain and / or side chain. Specifically, (1) norbornene polymer, (2) monocyclic olefin polymer, (3) cyclic conjugated diene polymer, (4) vinyl alicyclic hydrocarbon polymer, and these A hydride etc. are mentioned. Among these, norbornene-based polymers are more preferable from the viewpoints of transparency and moldability. Examples of the resin having these alicyclic structures include those described in JP-A No. 05-310845, JP-A No. 05-097978, and US Pat. No. 6,511,756.

  Specific examples of the norbornene-based polymer include ring-opening polymers of norbornene-based monomers, ring-opening copolymers of norbornene-based monomers and other monomers capable of ring-opening copolymerization, hydrides thereof, and norbornene-based monomers. And addition copolymers with other monomers copolymerizable with norbornene monomers.

  The methacrylic resin is a polymer having a methacrylic acid ester as a main component, and includes a methacrylic acid ester homopolymer and a copolymer of a methacrylic acid ester and other monomers. Usually, alkyl methacrylate is used. In the case of a copolymer, acrylic acid esters, aromatic vinyl compounds, vinylcyan compounds, etc. are used as other monomers copolymerized with methacrylic acid esters.

  As a preferred specific embodiment of the optically anisotropic element used in the present invention, a multilayer film formed by laminating a film (b layer) made of another thermoplastic resin on both surfaces of a film (a layer) made of polystyrene resin. A stretched multilayer film formed by stretching can be mentioned. Hereinafter, this specific embodiment will be described.

  As the polystyrene resin constituting the a layer, the same “styrene resin” as described above can be used.

  The polystyrene resin constituting the a layer preferably has a glass transition temperature of 120 ° C. or higher, more preferably 120 to 200 ° C., and still more preferably 120 to 140 ° C.

  In the present invention, the polystyrene resin and the other thermoplastic resin have Tg (a)> Tg (b) when their glass transition temperatures are Tg (a) (° C.) and Tg (b) (° C.), respectively. ) It is preferable to satisfy the relationship of + 20 ° C. By satisfying such a relationship, optical anisotropy can be effectively given to the a layer made of polystyrene resin when stretched, and a good optical anisotropic element can be obtained.

  The method of laminating the polystyrene resin that is the material of the a layer and the other thermoplastic resin that is the material of the b layer to form a multilayer film is not particularly limited, but is a coextrusion T-die method, coextrusion inflation Known methods such as a method of forming by coextrusion such as a method, a coextrusion lamination method, a film lamination forming method such as dry lamination, and a coating forming method may be appropriately used. Among these, a molding method by coextrusion is preferable from the viewpoints of production efficiency and that volatile components such as a solvent do not remain in the film. The extrusion temperature can be appropriately selected according to the type of the polystyrene resin used and the other thermoplastic resin.

  The multilayer film is formed by laminating the b layer on both surfaces of the a layer. An adhesive layer or a pressure-sensitive adhesive layer can be provided between the a layer and the b layer, but the a layer and the b layer are directly laminated (that is, lamination of a three-layer configuration of b layer / a layer / b layer). Body). In the multilayer film, the thickness of the a layer and the b layer laminated on both sides thereof is not particularly limited, but preferably 10 to 300 μm and 10 to 400 μm, respectively.

The stretched multilayer film is formed by stretching the multilayer film. The stretched multilayer film may include an A layer provided by stretching the a layer and a B layer provided by stretching the b layer. The stretched multilayer film is a stretched film having a three-layer structure of B layer / A layer / B layer formed by stretching a laminate of b layer / a layer / b layer of the multilayer film. It is preferable.
The stretching can be preferably performed by uniaxial stretching or oblique stretching, and more preferably by uniaxial stretching or oblique stretching by a tenter.

  The front direction retardation Re and the thickness direction retardation Rth of the optically anisotropic element can be produced by appropriately adjusting stretching conditions such as a stretching temperature and a stretching ratio. The stretching temperature is preferably Tg (a) -10 ° C to Tg (a) + 20 ° C, and more preferably in the range of Tg (a) -5 ° C to Tg (a) + 15 ° C. The draw ratio is preferably 1.05 to 30 times, and more preferably 1.1 to 10 times. If the stretching temperature and the stretching ratio are out of the above ranges, the orientation may be insufficient and the refractive index anisotropy and thus the retardation may be insufficiently developed, or the laminate may be broken.

  The thickness of the optically anisotropic element is preferably 50 to 1000 μm, more preferably 50 to 600 μm.

(Light diffusion adhesive layer)
The projection screen of the present invention includes a light diffusive adhesive layer provided between the retardation layer and the circularly polarized light separating layer. Further layers may be interposed between the retardation layer and the light diffusive adhesive layer, and between the light diffusible adhesive layer and the circularly polarized light separating layer, but preferably the retardation layer and the circular layer. The polarization separation layer is attached via the material of the light diffusive adhesive layer, and the retardation layer and the circularly polarized light separation layer are provided in direct contact with the light diffusable adhesive layer as shown in FIG.
As a material for the light diffusive adhesive layer, a material exhibiting adhesiveness at normal temperature (20 ± 15 ° C .: JIS standard) is preferable. Here, “adhesive” means that the adhesive has a ball number of 2 or more as measured by a tilting ball tack measurement according to JIS Z0237.

  In the present invention, the light diffusive adhesive layer contains a light diffusing agent, and preferably contains a light diffusing agent and an adhesive resin.

  A preferable blending ratio of the light diffusing agent in the light diffusing adhesive layer material is 0.1 to 20 parts by weight, more preferably 1 to 10 parts by weight with respect to 100 parts by weight of the adhesive resin.

  The ratio of the average primary particle (arrow 141 in FIG. 2) d of the light diffusing agent contained in the light diffusing adhesive layer to the thickness l of the light diffusing adhesive layer is preferably 0.05 ≦ d / l ≦ 0.75. Particularly preferably, 0.07 ≦ d / l ≦ 0.65. If it is less than 0.05, the particle size of the particles is too small, or the film thickness of the light diffusable adhesive layer is too thick. There is a possibility that the pressure-sensitive adhesive layer may generate an unnecessary phase difference, and when it exceeds 0.75, a necessary adhesion area cannot be obtained, the pressure-sensitive adhesive force is insufficient, and the light-diffusing pressure-sensitive adhesive layer may be peeled off. The thickness l of the light diffusable adhesive layer is not particularly limited, but can be in the range of 2 to 50 μm, and preferably 5 to 30 μm.

  The haze of the light diffusable pressure-sensitive adhesive layer is preferably 10% to 90%, particularly preferably 30% to 80%. By setting the haze within this range, the light in the light diffusable adhesive layer can be averaged while maintaining high transparency without whitening the entire film. Examples of a method for adjusting the haze to the above range include appropriately adjusting the blending ratio of the light diffusing agent. In addition, the measurement of haze is performed using a haze meter (for example, haze guard II (made by Toyo Seiki Co., Ltd.)).

  As the adhesive resin constituting the light diffusive adhesive layer, the following specific adhesive resin composition can be preferably used.

(Adhesive resin composition)
The adhesive resin composition in this invention contains the main polymer which comprises an adhesive at least.
Examples of the main polymer include acrylic polymers and acrylic copolymers, silicone polymers, polyesters, polyurethanes, polyamides, polyvinyl ethers, polyvinyl alcohols, ethylene / vinyl acetate copolymers, ethylene / acrylic ester copolymers, Examples include ethylene / vinyl chloride copolymer, thermoplastic elastomer, epoxy, natural rubber, and synthetic rubber. Among these, a thermoplastic elastomer, an ethylene / vinyl acetate copolymer, and an ethylene / acrylic acid ester copolymer are preferable because they are excellent in transparency, exhibit appropriate wettability and cohesion, and have excellent weather resistance. Thermoplastic elastomer is a resin having rubber elasticity at room temperature without vulcanization treatment. Specifically, styrene-butadiene block copolymer, styrene-ethylene block copolymer, styrene-butadiene- Styrene block copolymer, styrene-isoprene-styrene block copolymer, styrene-ethylenebutylene-styrene block copolymer, styrene-ethylenepropylene-styrene block copolymer, ethylene-propylene copolymer and ethylene-propylene terpolymer , Polyethylene, polypropylene, and those having a carboxyl group or a sulfonyl group introduced thereto. The molecular weight of these main polymers is the weight average molecular weight (Mw) of polyisoprene measured by gel permeation chromatography, and is usually 10,000 to 500,000, preferably 20,000 to 400, 000.

  According to the kind of main polymer, another compounding agent can be mix | blended with the said adhesive resin composition. Examples of other compounding agents include tackifiers, crosslinking agents or curing agents, antioxidants, antifoaming agents, and stabilizers.

  The tackifier imparts adhesive force to the main polymer that is soft and has a solid surface that is easily wetted. Such tackifiers include rosin and rosin derivatives, polyterpene resins, terpene phenol resins, coumarone-indene resins, petroleum resins, hydrogenated petroleum resins and the like. Among these, petroleum resins, hydrogenated petroleum resins, and terpene phenol resins are preferable because they are excellent in transparency and compatibility with the main polymer. The compounding amount of the tackifier is preferably 2 to 50 parts by weight, more preferably 5 to 20 parts by weight with respect to 100 parts by weight of the main polymer. When the addition amount of the tackifier is less than 2 parts by weight, the effect of the tackifier is not expressed, and conversely, when the addition amount exceeds 50 parts by weight, the adhesive force decreases due to the decrease in the cohesive force of the adhesive. Tend to be.

  Examples of the crosslinking agent or curing agent include polyfunctional isocyanate crosslinking agents such as tolylene diisocyanate, hexamethylene diisocyanate, tetramethylene diisocyanate, trimethylolpropane tolylene diisocyanate, diphenylmethane triisocyanate; ethylene glycol glycidyl ether, polyethylene glycol di Epoxy crosslinking agents or curing agents such as glycidyl ether, diglycidyl ether, trimethylolpropane triglycidyl ether; vinyltrimethoxysilane, methacryloxypropyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 2- (3 , 4-Epoxycyclohexyl) ethyltrimethoxysilane, 3-aminopropyltrimethoxysilane, N- (2-aminoethyl) A silane crosslinking agent or curing agent such as 3-aminopropyltrimethoxysilane; a melamine resin crosslinking agent; a metal chelate crosslinking agent; an amine crosslinking agent is used. The blending amount of the crosslinking agent or curing agent is preferably 0.001 to 10 parts by weight, more preferably 0.01 to 3 parts by weight with respect to 100 parts by weight of the main polymer. When the addition amount of the crosslinking agent or curing agent is less than 0.001 part by weight, the effect of the crosslinking agent is not exhibited, and foaming and peeling are conspicuous in a weather resistance test or the like. On the contrary, when the addition amount of the crosslinking agent or the curing agent is more than 10 parts by weight, the stress relaxation property of the adhesive is lowered, and warpage becomes conspicuous.

  Examples of the antioxidant include phenol-based antioxidants such as tetrakis (methylene-3- (3,5di-t-butyl-4-hydroxyphenyl) propionate) methane, phosphorus-based antioxidants, and thioether-based antioxidants. Is mentioned. The blending amount of the antioxidant is within a range in which the transparency and adhesive strength of the adhesive layer are not lowered.

  The adhesive resin composition preferably has a shear storage modulus at a temperature of 23 ° C. of 0.1 to 10 MPa. By setting the shear storage elastic modulus in such a range, the pressure-sensitive adhesive composition has an appropriate pressure-sensitive adhesiveness (that is, a property capable of easily holding the adherend to stick the adherend and easily peeled off). obtain.

  The refractive index of the adhesive resin composition is preferably in the range of 1.45 to 1.55. By setting the refractive index within this range, it is possible to prevent interface reflection in the configuration of the circularly polarized light separating layer, the light diffusing adhesive layer, and the retardation layer.

(Light diffusing agent)
In the present invention, the gradient refractive index particles described below can be used as a particularly preferred light diffusing agent.

(Gradient refractive index particles)
In the present invention, the gradient refractive index particles contained in the light diffusive pressure-sensitive adhesive layer refer to particles having a refractive index gradient that changes as the depth from the surface to the center increases. Here, the refractive index gradient may exist in the entire range in the depth direction from the surface of the particle to the center, but exists in a partial range in the depth direction from the surface of the particle to the center. It may be. Specifically, for example, a core having a uniform refractive index and a coating layer covering the core and having a refractive index gradient in the thickness direction can be provided.

  An example of such gradient refractive index particles will be described with reference to FIG. In FIG. 2, the gradient refractive index particle 125 is a spherical particle composed of a nucleus 125C and a coating layer 125D covering the periphery thereof. Since the core 125C has a substantially uniform refractive index, there is no refractive index gradient in its radial direction (ie, the depth direction from the particle surface) 142. On the other hand, the coating layer 125 </ b> D has a refractive index gradient along its thickness direction (that is, a depth direction from the particle surface) 143.

  The gradient of the coating layer is a gradient close to the nucleus at the interface 125B between the nucleus 125C and the coating layer 125D, and close to other materials (such as an adhesive resin composition) surrounding the periphery of the surface 125S of the particle 125. Is preferred. For example, when the light diffusing adhesive layer material includes a binder made of the adhesive resin composition and a filler made of gradient refractive index particles, the refractive index of the adhesive resin composition is smaller than the refractive index of the core 125C. In this case, it is preferable that the gradient of the refractive index of the coating layer 125D is a gradient that increases the refractive index from the surface 125S toward the interface 125B.

More preferably, the refractive index of the coating layer 125D at the interface 125B, the refractive index of the coating layer 125D at the surface 125S, the refractive index of the core 125C, and the refractive index of the adhesive resin composition are expressed as n _B , n _S , n _C and When n _o, preferably satisfy the relationship of formula (III) ~ formula (VI).
0.05 ≦ | n _B −n _S | (III)
0.05 ≦ | n _C −n _o | ≦ 0.5 (IV)
0 ≦ | n _C −n _B | ≦ 0.1 (V)
0 ≦ | n _S −n _o | ≦ 0.2 (VI)

The absolute value of the difference between n _B and n _S is preferably 0.05 or more, and more preferably 0.1 or more, as in formula (III). It is further preferable to have a gentle refractive index gradient (gradient) between the pressure-sensitive adhesive composition and the core through the coating layer.

n _C and _{n o} is preferably the absolute value of the difference as the formula (IV) is 0.05 or more and 0.5 or less, further still more preferably 0.05 to 0.3. If the absolute value of the difference in refractive index is smaller than 0.05, a sufficient light diffusion effect cannot be obtained, and if it is larger than 0.5, the transparency is deteriorated and the function as a screen is deteriorated. .

As for n _C and n _B , the absolute value of the difference is preferably 0 or more and 0.1 or less, and more preferably 0 or more and 0.06 or less, as in formula (V). If the absolute value of the difference in refractive index is larger than 0.1, the scattering property inside the particles is increased, and the polarization maintaining and diffusing function is deteriorated.

n _S and _{n o} is preferably the absolute value of the difference as the formula (VI) is 0 to 0.2, more preferably still at 0 to 0.12. If the absolute value of the difference in refractive index is larger than 0.2, the scattering property inside the light diffusing adhesive layer is increased, and the polarization maintaining / diffusing function is deteriorated.

  The shape of the gradient refractive index particles is preferably spherical, from the viewpoint that the light diffusion direction can be isotropic, but may be a shape such as an elliptic rotating body deviating from the spherical shape. The particle diameter 141 of the gradient refractive index particles is not particularly limited, but is preferably 0.5 to 20 μm as an average primary particle diameter. In addition, when the diameter here is not a perfect sphere, the diameter of the sphere of the same volume is substituted. The ratio of the radius 142 of the core 125D to the thickness 143 of the coating layer 125D is preferably 2: 3 to 3: 2.

The gradient refractive index particles are not particularly limited as long as they are transparent particles, but fine particles are preferable from the viewpoint of obtaining a more excellent light diffusion effect. The fine particles are not particularly limited as long as they can form a refractive index gradient structure. Examples thereof include organic fine particles and inorganic fine particles.
Examples of the organic fine particles include acrylic fine particles, styrene fine particles, silicone fine particles, styrene-butadiene fine particles, acrylic-acrylic core-shell fine particles, and acrylic-styrene-butadiene core-shell fine particles. In particular, core-shell type fine particles are preferable in forming a gradient refractive index.
As inorganic fine particles, for example, by coating metal alkoxide solutions having different compositions on the surface of fine particles having a high refractive index such as titanium oxide, inorganic fine particles in which the refractive index of the coating layer is continuously or stepwise can be produced. it can.

  The organic fine particles having a gradient refractive index can be prepared using an emulsion polymerization method, a seed polymerization method, a suspension polymerization method, or the like. Specifically, in the initial stage, the monomer (A) whose homopolymer exhibits a high refractive index is polymerized to form a high refractive index at the center of the fine particles. Thereafter, the monomer (B) having a refractive index smaller than that of the homopolymer (A) and having the same refractive index as that of the adhesive resin as a matrix, or smaller than that of the adhesive resin as a matrix (B ) And the mixture of (A) are added to the polymerization system by changing the ratio of (A) and (B), so that the refractive index is continuous as the central part has a high refractive index and goes to the particle coating layer part. Organic fine particles inclined in a target or stepwise manner can be produced.

In the present invention, the light diffusive adhesive layer contains the above gradient refractive index particles as a diffusing agent that diffuses the light transmitted through the light diffusive adhesive layer, thereby reducing the change in the polarization state of light. Can achieve diffusion. That is, the light incident on the gradient refractive index particle changes its traveling direction and polarization state as it passes through the layer having the gradient refractive index inside the particle, and the change of the polarization state is caused by the light path at the center of the particle. Maximum when approaching. However, until the light path moves away from the center of the particle and exits from the particle surface again, the change in the polarization state is canceled, and when the light exits, only the light traveling direction changes in the same polarization state as the incident light. Is done.
In this way, by changing the traveling direction of light with little change in polarization state, it is possible to obtain good selective reflection of the image light on the circularly polarized light separation layer, and at the same time, the desired image light of the image screen. Scattering can be obtained.

(Other light diffusing agents)
The light diffusive adhesive layer may contain other light diffusing agent as a light diffusing agent in addition to or in place of the inclined refractive index particles. Such other light diffusing agents include inorganic and organic fillers. Inorganic fillers include glass, silicon oxide, aluminum hydroxide, aluminum oxide, titanium oxide, zinc oxide, barium sulfate, magnesium silicate, etc .; organic fillers include fluororesin, polystyrene resin, acrylic resin, polycarbonate resin, Examples thereof include silicone resin, polyethylene resin, ethylene-vinyl acetate copolymer, acrylonitrile, polyurethane, polyvinyl chloride, polyacrylonitrile, polyamide, polysiloxane resin, melamine resin, benzoguanamine resin, or a cross-linked product thereof.

(Arbitrary component layer)
The projection screen of the present invention can optionally further include other layers in addition to the support substrate, the circularly polarized light separating layer, the retardation layer, and the light diffusing adhesive layer. Specifically, for example, a layer having functions such as a hard coat layer and an antireflection layer, or a combination thereof can be provided on the projection surface side of the retardation layer via an adhesive layer.

Examples of the material constituting the hard coat layer include those obtained by photopolymerizing and curing a composition containing a photopolymerizable prepolymer or a photopolymerizable monomer. Examples of the photopolymerizable prepolymer include polyester acrylate, epoxy acrylate, urethane acrylate, and polyol acrylate. These photopolymerizable prepolymers may be used alone or in combination of two or more. Examples of the photopolymerizable monomer include polymethylolpropane triacrylate, polymethylolpropane trimethacrylate, hexanediol acrylate, hexanediol methacrylate, tripropylene glycol diacrylate, tripropylene glycol dimethacrylate, diethylene glycol diacrylate, diethylene glycol dimethacrylate, Pentaerythritol triacrylate, pentaerythritol trimethacrylate, dipentaerythritol hexaacrylate, dipentaerythritol hexamethacrylate, 1,6-hexanediol diacrylate, 1,6-hexanediol dimethacrylate, neopentyl glycol diacrylate, neopentyl glycol di Methacrylate etc. It is.
Examples of the photopolymerization initiator in this case include acetophenones, benzophenones, α-amyloxime esters, tetramethylchuram monosulfide, thioxanthones, and the like. Moreover, n-butylamine, triethylamine, poly-n-butylphosphine, etc. can be used individually or in mixture with a photosensitizer. Furthermore, antimony pentoxide, tin oxide, tin oxide doped with phosphorus (PTO), tin oxide doped with antimony (ATO), indium oxide doped with tin (ITO), indium oxide doped with zinc (ITO) IZO), zinc oxide doped with aluminum (AZO), tin oxide doped with fluorine (FTO), zinc oxide / aluminum oxide, zinc antimonate, etc. it can.
Further, as the material constituting the anti-reflection layer, the general _{^{formula, R 1H n Si (OR 2H}} ) m ( ^{wherein, R IH} hydrocarbon group optionally monovalent be substituted, OR ² Represents a hydrolyzable group, n and m represent integers, m is 1 to 4, and m + n is 4. This is obtained by hydrolyzing all or part of the silicon compound represented by Things can be used. Examples of the monovalent hydrocarbon group R ^1H which may have a substituent include an alkyl group, a phenyl group, a cycloalkyl group, an aryl group, a haloalkyl group; an alkenylcarbonyloxyalkyl group; an alkyl group having an epoxy group, and a mercapto group. And an alkyl group having an amino group, an alkyl group having an amino group, and a perfluoroalkyl group.
Specific examples of the hydrolyzable group include an alkoxyl group such as a methoxy group, an ethoxy group, and a propoxy group; an acyloxy group such as an acetoxy group and a propionyloxy group; an oxime group (—O— ^N═C —R ^1J (R ^2J ). ), Enoxy group (—O—C (R ^1J ) = C (R ^2J ) R ^3J ), amino group, aminoxy group (—O—N (R ^1J ) R ^2J ), amide group (—N (R ^1J ) -C (= O) ^-R2J ) and the like. In these groups, R ^1J , R ^2J and R ^3J each independently represent a hydrogen atom or a monovalent hydrocarbon group.
As the silicon compound represented by R ^1H _n Si (OR ^2H ) _m , a silicon compound in which n is an integer of 0 to 2 is preferable. Specific examples thereof include alkoxysilanes, acetoxysilanes, oxime silanes, enoxysilanes, aminosilanes, aminoxysilanes, amidosilanes and the like. Examples of the tetraalkoxysilane in which n is 0 include tetramethoxysilane and tetraethoxysilane. Examples of the organotrialkoxysilane in which n is 1 include methyltrimethoxysilane, methyltriethoxysilane, and methyltriisopropoxysilane. And phenyltrimethoxysilane, phenyltriethoxysilane, 3,3,3-trifluoropropyltrimethoxysilane and the like. Examples of the diorganodialkoxysilane in which n is 2 include dimethyldimethoxysilane, dimethyldiethoxysilane, diphenyldimethoxysilane, diphenyldiethoxysilane, and methylphenyldimethoxysilane.

  Furthermore, you may provide other layers, such as an adhesion layer, between a support base material and a circularly polarized light separation layer as needed. As the material for the adhesive layer, a resin composition similar to the adhesive diffusion layer resin composition described above can be used.

  As another example of the layer of an arbitrary component, an absorption layer that absorbs incident light through the circularly polarized light separation layer can be provided separately from the support base material. Such an absorption layer can be provided, for example, on the opposite side of the projection surface 131 of the support substrate 150 in the projection screen example 100 shown in FIG. Although the material of this absorption layer is not specifically limited, It can be set as the resin composition etc. containing black pigments, such as carbon.

(Production of projection screen)
The production method of the projection screen of the present invention is not particularly limited, but (a) a circularly polarized light separating layer is prepared on a support substrate, and then the circularly polarized light separating layer and the retardation layer are pasted, and ( (B) A method of preparing a supporting substrate, a circularly polarized light separating layer and a retardation layer separately and sticking them in an arbitrary order can be mentioned.

  In the case of the above method (a), in the above-described method for preparing the circularly polarized light separating layer, a supporting base material is used as the base material, and an orientation film is provided thereon as necessary. A layer can be provided, which can be further affixed with a separately prepared retardation layer.

  In the case of the above method (b), in the above-described method for forming the circularly polarized light separating layer, a substrate other than the supporting base material is used, and the obtained circularly polarized light separating layer and the other layers are pasted in an arbitrary order. Can do.

  In both cases of the methods (a) and (b), when the circularly polarized light separating layer and the retardation layer are stuck, these are stuck by using the above-mentioned light diffusable adhesive layer material as an adhesive. A light diffusable adhesive layer can be formed between them. Specifically, a light diffusable pressure-sensitive adhesive layer can be formed by applying a light diffusive pressure-sensitive adhesive layer material to one or both of these surfaces and further curing as necessary.

  The coating method of the light diffusive adhesive layer material is not particularly limited, and examples thereof include a roll coating method, a gravure coating method, a spin coating method, and a bar coating method. In addition, when the light diffusive adhesive layer material is directly applied to the circularly polarized light separating layer or the retardation layer, the coating surface is appropriately subjected to plasma discharge treatment or corona prior to coating in order to improve wettability and adhesion. You may use for processes, such as a discharge process, an ultraviolet-ray process, or a flame process.

  The step of curing the layer of the light diffusive pressure-sensitive adhesive layer material as necessary after laminating the retardation layer and the circularly polarized light separating layer is a temperature range of 40 ° C. to 110 ° C., preferably 60 ° C. to 100 ° C. This can be done by heating.

  Furthermore, in any of the methods (A) and (B), any other layer such as an absorption layer can be appropriately formed before or after the methods (A) and (B).

(Projection system)
The projection system of the present invention includes the projection screen of the present invention and an image projector. As the image projector, a liquid crystal projector that emits polarized light as image light, controls the image light by a liquid crystal cell, and emits linearly polarized light as image light is particularly preferable.

  Hereinafter, the present invention will be described by way of examples. In addition, this invention is not limited by the following examples.

<Production Example 1: Preparation of gradient refractive index particles 1>
In the following procedure, spherical gradient refractive index particles having the form shown in FIG. 2 were obtained.
A stainless steel reactor equipped with a stirrer was charged with 75 parts by weight of deionized water, 1.0 part by weight of polyvinyl alcohol as a dispersant, and 0.6 parts by weight of benzoyl peroxide as a radical initiator. After nitrogen substitution, 40 parts by weight of α-methylstyrene and 3 parts by weight of divinylbenzene were added and stirred to make an emulsion. The emulsion was transferred to a separately degassed autoclave, and the temperature was raised to 65 ° C. while stirring with a homogenizer, and polymerization was performed for 2 hours.

Next, polymerization liquid A (250 parts by weight of deionized water, 3 parts by weight of polyvinyl alcohol as a dispersing agent, 2.5 parts by weight of benzoyl peroxide as a radical initiator was added, and after substituting with nitrogen by vacuum degassing, α -100 parts by weight of methyl styrene and 10 parts by weight of divinylbenzene emulsified) and 100 parts by weight of a mixed solution of polymerization liquid B (in which the monomer of polymerization liquid A is changed to methyl methacrylate) (polymerization liquid A Was added to the autoclave, and polymerization was carried out for 30 minutes. Next, 100 parts by weight of the second mixed liquid (75 parts by weight of the polymerization liquid A and 25 parts by weight of the polymerization liquid B) was added to the autoclave, and polymerization was performed for 30 minutes. Subsequently, 100 parts by weight of the third liquid mixture (62 parts by weight of the polymer liquid A, 28 parts by weight of the polymer liquid B), 100 parts by weight of the fourth liquid mixture (50 parts by weight of the polymer liquid A, 50 parts by weight) 100 parts by weight of the fifth mixture (40 parts by weight of polymerization liquid A, 60 parts by weight of polymerization liquid B), 100 parts by weight of the sixth mixture (28 parts of polymerization liquid A, polymerization liquid B) Is 72 parts by weight), 100 parts by weight of the seventh mixed solution (20 parts by weight of the polymer solution A, 80 parts by weight of the polymer solution B), and 100 parts by weight of the eighth mixed solution (the polymer solution A is 12 parts by weight, The polymerization liquid B was used in the order of 88 parts by weight), and the same operation as the polymerization with the second liquid mixture was performed. Subsequently, 100 parts by weight of the 9th mixed solution (7 parts by weight of the polymer solution A and 93 parts by weight of the polymer solution B) were added to the autoclave, and the polymerization was completed after cooling for 2 hours. A polymer bead dispersion was obtained.
The obtained polymer bead dispersion was filtered, washed, dried, and sieved (particles of 50 μm or more were removed) to obtain spherical gradient refractive index particles 125 of the embodiment shown in FIG.
The average particle diameter 141 of the obtained gradient refractive index particles 125 is 18.5 μm, the average of the radius 142 of the core 125C is 8.5 μm, and the average of the thickness 143 of the gradient refractive index coating layer 125D is 10. It was 0 μm. The refractive index of the coating layer 125D on the surface 125S of the particle 125 is 1.50, the refractive index of the coating layer 125D at the boundary 125B between the nucleus 125C and the coating layer 125D is 1.67, and the refractive index of the nucleus 125C. Was 1.73. The refractive index distribution was measured using a differential interference microscope (Interphako, manufactured by Carl-Zeiss).

<Production Example 2: Preparation of gradient refractive index particles 2>
Gradient refractive index particles were obtained in the same manner as in Production Example 1 except that the monomer α-methylstyrene was changed to vinyl naphthalene.
The average particle diameter 141 of the obtained gradient refractive index particles is 15.5 μm, the average of the radius 142 of the core 125C is 7.5 μm, and the average of the thickness 143 of the gradient refractive index coating layer 125D is 8.0 μm. Met. The refractive index of the coating layer 125D at the surface 125S of the particle 125 is 1.42, the refractive index of the coating layer 125D at the boundary 125B between the nucleus 125C and the coating layer 125D is 1.65, and the refractive index of the nucleus 125C. Was 1.68.

<Production Example 3: Preparation of light diffusing agent>
A stainless steel reactor equipped with a stirrer was charged with 300 parts by weight of deionized water, 1.0 part by weight of polyvinyl alcohol as a dispersant, and 0.6 parts by weight of benzoyl peroxide as a radical initiator. After nitrogen substitution, 40 parts by weight of α-methylstyrene and 3 parts by weight of divinylbenzene were added and stirred to make an emulsion. The emulsion was transferred to a separately degassed autoclave, and the temperature was raised to 65 ° C. while stirring with a homogenizer, and polymerization was performed for 2 hours.
Next, polymerization liquid A (250 parts by weight of deionized water, 3 parts by weight of polyvinyl alcohol as a dispersing agent, 2.5 parts by weight of benzoyl peroxide as a radical initiator was added, and after substituting with nitrogen by vacuum degassing, α -Emulsified by stirring 60 parts by weight of methylstyrene and 40 parts by weight of divinylbenzene), 100 parts by weight of a mixed solution of Polymer B (in which the monomer of Polymer A is changed to methyl methacrylate) (Polymer A) Was added to the autoclave, and the polymerization was terminated when polymerization was performed for 2 hours to obtain a polymer bead dispersion.
The obtained polymer bead dispersion was filtered, washed and dried, and sieved (particles of 50 μm or more were removed) to obtain particles having a core-shell structure.
The average particle diameter of the obtained particles was 9.5 μm, the average nucleus radius was 4.5 μm, and the average thickness of the coating layer was 5.0 μm. The refractive index of the coating layer on the particle surface was 1.52, the refractive index of the coating layer at the boundary between the nucleus and the coating layer was 1.53, and the refractive index of the nucleus was 1.65.

<Production Example 4: Preparation of circularly polarized light separating layer>
One side of a film (manufactured by Optes Co., Ltd.) made of an alicyclic olefin polymer having a thickness of 100 μm, a width of 50 mm, and a length of 200 mm was subjected to corona discharge treatment so that the wetting index of the surface was 56 dyne / cm. This was used as a base film for producing a circularly polarized light separating layer.
5% modified polyamide (FR105 / CM4000 70/30 mixture, FR105: methoxymethylated nylon manufactured by Lead City Co., Ltd. CM4000: Toray on the surface of the base film subjected to the corona discharge treatment. An aqueous solution of a copolymerized polyamide) was applied. After coating, the film was dried at 120 ° C. for 5 minutes to produce a dry film having a thickness of 0.1 μm.

  The dry film was rubbed in one direction to obtain an alignment film. On the prepared alignment film, a coating solution having the following composition was applied using a wire bar # 6, dried at 100 ° C. for 5 minutes, and subjected to orientation aging.

[Coating liquid composition for forming cholesteric resin layer]
Solid content: 40% by weight
Rod-like liquid crystalline compound (rod-like liquid crystalline compound having Δn (= ne-no) = 0.18) 29.0 parts by weight A1 compound (compound represented by (A1); melting point 66 ° C.) 7.5 parts Light Polymerization initiator (IRG907 manufactured by Ciba Specialty Chemicals) 1.2 parts by weight Surfactant (KH-40 manufactured by Seimi Chemical Co., Ltd.) 0.04 parts by weight Chiral agent (LC756 manufactured by BASF) 2.3 parts by weight Methyl ethyl ketone (SP value: 9.3) 60 parts by weight

The coating film was irradiated with ultraviolet rays of 70 mJ / cm ² (UV-A), held at 100 ° C. for 1 to 5 minutes, then irradiated with ultraviolet rays to cure the coating film, and a cholesteric resin layer having a thickness of 3 μm ( A circularly polarized light separating sheet 1 having an optical functional layer) was obtained. This cholesteric resin layer has an average value of light transmittance from 400 nm to 570 nm of about 55%, and it was found that the remaining 45% including interface reflection is reflected.

In the production of the circularly polarized light separating sheet 1, the same procedure was performed except that 29.0 parts by weight of the polymerizable liquid crystalline compound was changed to 29.4 parts by weight and 2.3 parts by weight of the chiral agent was changed to 1.9 parts by weight. A circularly polarized light separating sheet 2 was obtained. This cholesteric resin layer had an average light transmittance of about 55% from 560 to 730 nm, and it was found that the remaining 45% including the interface reflection was reflected.
The cholesteric resin layer side of the produced circularly polarized light separating sheet 2 is bonded and fixed to the base film side of the circularly polarized light separating sheet 1 through an adhesive (manufactured by Sumitomo 3M, “8142”), and the circularly polarized light separating layer Got.

<Production Example 5: Production of optically anisotropic element>
A monomer composition composed of 97.8% by weight of methyl methacrylate and 2.2% by weight of methyl acrylate was polymerized by a bulk polymerization method to obtain resin pellets.

  Rubber particles were produced according to Example 3 of JP-B-55-27576. This rubber particle has a spherical three-layer structure, the core inner layer is a crosslinked polymer of methyl methacrylate and a small amount of allyl methacrylate, and the inner layer is composed of butyl acrylate and styrene as main components and a small amount of acrylic acid. It is a soft elastic copolymer obtained by crosslinking and copolymerizing allyl, and the outer layer is a hard polymer of methyl methacrylate and a small amount of ethyl acrylate. The average particle size of the inner layer was 0.19 μm, and the particle size including the outer layer was 0.22 μm.

  70 parts by weight of the resin pellets and 30 parts by weight of the rubber particles were mixed and melt kneaded with a twin screw extruder to obtain a methacrylic acid ester polymer composition A (glass transition temperature 105 ° C.).

  By coextruding the methacrylic ester polymer composition A (b layer) and the styrene maleic anhydride copolymer (glass transition temperature 130 ° C.) (a layer) at a temperature of 280 ° C., a b layer / a layer A multilayer film having an average thickness of 45/70/45 (μm) with a three-layer structure of / b layers was obtained. The laminated film was obliquely stretched with a tenter stretching machine at a stretching temperature of 134 ° C. and a stretching ratio of 1.8 times so that the slow axis was inclined at 45 degrees with respect to the MD direction. Got.

  The retardation in the front direction of the optically anisotropic element was 140 nm, and the retardation in the thickness direction was −85 nm (each numerical value is a measured value after oblique stretching). Furthermore, both surfaces of this optically anisotropic layer were subjected to corona discharge treatment so that the wetting index was 56 dyne / cm.

<Example 1>
(1-1: Preparation of laminate of circularly polarized light separating layer and optically anisotropic layer)
The gradient refractive index particles obtained in Production Example 1 were mixed with an acrylic emulsion-based pressure-sensitive adhesive (manufactured by Daido Kasei; Vinisole E-5301, refractive index 1.53) to obtain a light-diffusing pressure-sensitive adhesive layer material. The blending ratio of the gradient refractive index particles was 3 parts by weight with respect to 100 parts by weight of the pressure-sensitive adhesive. This light-diffusing adhesive layer material was laminated on the cholesteric resin layer of the circularly polarized light separating layer obtained in Production Example 4 so as to have an average thickness of 30 μm, and this layer and the optical anisotropy obtained in Production Example 5 were obtained. The layer was treated with a corona-treated surface using a laminator at 80 ° C. at a nip pressure of 2 kgf / 50 mm to obtain a laminate. The haze of the light diffusion adhesive layer was 60%.

(1-2: Production of projection screen)
Average thickness of acrylic emulsion-based pressure-sensitive adhesive (manufactured by Daido Kasei; Vinisole E-5301) on one side of a supporting substrate (Lumirror / AC-X, manufactured by Panac Corporation, a substrate having an easy-adhesion layer formed on a black PET film) Was applied to be 25 μm, and this and the surface of the laminate obtained in (1-1) on the substrate side of the circularly polarized light separating layer were bonded together to obtain a projection screen.

(1-3: Evaluation of projection screen)
Ambient light is a fluorescent lamp installed on the ceiling (which emits unpolarized light) and is placed so that illumination light is irradiated onto the projection screen at an angle of about 45 degrees from the ceiling. The brightness at was measured with a illuminometer (digital illuminometer 51001, manufactured by Yokogawa Meter & Instruments), and was 120 lux (lx).
The projection screen obtained in (1-2) was installed perpendicular to the floor while the room illumination (ambient light) was turned on. Further, an image projector (PRO xtra X; manufactured by Sanyo Electric Co., Ltd.) was disposed at a position approximately 2 m away from the projection screen in a direction perpendicular to the projection screen (a direction parallel to the floor). In this state, image light (a still image with white and black areas) was projected onto the projection screen by the image projector, and observed visually from the front of the projection screen near the position where the image projector was placed.
As a result, a bright, clear and high-contrast video was obtained, and the image projector light source was not visible.

<Example 2>
A projection screen was obtained and evaluated in the same manner as in Example 1 except that the gradient refractive index particles used were those obtained in Production Example 2 instead of those obtained in Production Example 1. The haze of the light diffusion adhesive layer was 60%. As a result, a bright and clear image with high contrast was obtained as in Example 1, and the image projector light source was not visible.

<Example 3>
A projection screen was obtained and evaluated in the same manner as in Example 1 except that the particles obtained in Production Example 3 were used instead of the gradient refractive index particles obtained in Production Example 1. The haze of the light diffusion adhesive layer was 60%. As a result, although the brightness was inferior to that of Example 1 and Example 2, a clear and high-contrast video was obtained, and the image projector light source was not visible.

<Comparative Example 1>
A projection screen was obtained and evaluated in the same manner as in Example 1 except that the gradient refractive index particles were not added to the light diffusing adhesive layer material. As a result, although the reflection of the image projector light source was not observed, the image became dark and the contrast was lowered, so that the image could not be fully recognized.

It is sectional drawing which shows an example of the projection screen of this invention. It is sectional drawing which shows roughly an example of the light-diffusion agent particle | grains in the projection screen of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Projection screen 110 Circularly polarized light separation layer 120 Light diffusable adhesive layer 125 Light diffusing agent particle 130 Phase difference layer 150 Support base material

Claims (4)

A projection screen comprising a supporting substrate, a circularly polarized light separating layer, and a retardation layer in this order,
A projection screen, further comprising a light diffusing adhesive layer containing a light diffusing agent between the circularly polarized light separating layer and the retardation layer.   The projection screen according to claim 1, wherein the light diffusing agent is a gradient refractive index particle.   The retardation layer is an optically anisotropic element having an in-plane retardation Re of substantially a quarter of transmitted light and a thickness direction retardation Rth of less than 0 nm. The projection screen according to 1 or 2.   A projection system comprising the projection screen according to claim 1 and an image projector.

Images