JP2018054827A - Prism sheet, optical sheet, display device and resin composition for prism sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a prism sheet excellent in optical performance.SOLUTION: A prism sheet includes a cured product of a resin composition, and has a surface with a plurality of linear prisms extending in one direction. The glass-transition temperature (Tg) of the cured product of the resin composition is 100°C or higher. The storage elastic modulus (E') of the cured product of the resin composition is 2.5×10[Pa] or more at 50°C. An arithmetic mean roughness (Ra) is 20 nm or less on a surface of the linear prisms.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a prism sheet, an optical sheet, a display device, and a resin composition for a prism sheet.

  A backlight unit is widely used for a display such as a liquid crystal display device. The backlight unit emits light to the display surface side through a light guide plate or a diffusion plate in order to make light from the light source uniform. In order to improve the front luminance of the emitted light, it is known to arrange a prism sheet on the light emitting surface side of the light guide plate or the diffusion plate.

In addition, a display device that allows an observer to observe an image source such as an LCD (Liquid Crystal Display) via an optical system has been proposed (for example, Patent Document 1).
Such a display device is applied to, for example, a head-up display in which an optical sheet is arranged on a front window of an automobile and image light projected from an image source is reflected to the driver side through the optical sheet. . In the head-up display, the viewer's field of view is obstructed by the displayed image. Therefore, a half mirror is used as the optical sheet, so that the image light and the external light are overlapped, so-called see-through. There is a case.

  In Patent Document 2, the present inventors have disclosed a first optical shape layer in which a plurality of unit optical shapes each having a first inclined surface and a second inclined surface are arranged, and a semi-transmissive type formed in the first inclined surface shape. A specific transflective reflective sheet having a reflective layer is disclosed.

JP 2010-78860 A Japanese Patent Application Laid-Open No. 2006-143053

In the semi-transmissive reflective sheet described in Patent Document 2, a metal layer is used as the semi-transmissive reflective layer. Further, a dielectric film described later can be used instead of the metal layer. In any case, the reflective layer is a thin layer, and the flatness of the thin layer is easily affected by the surface of the optical shape layer as a base, and when the flatness of the optical shape layer is poor, the reflective layer In some cases, the specularity of the glass deteriorated.
In addition, the flatness of the prism surface is also required from the viewpoint of the optical performance of the prism sheet.

  The present invention has been made in view of the above circumstances, a resin composition for a prism sheet capable of forming a prism sheet having a flat surface and suppressed shape change, a prism sheet excellent in optical performance, and transparency. An object is to provide an optical sheet excellent in specularity and a display device including the optical sheet.

The prism sheet according to the present invention is a prism sheet having a surface on which a plurality of linear prisms extending in one direction are arranged, which is made of a cured product of a resin composition,
The glass transition temperature (Tg) of the cured product of the resin composition is 100 ° C. or higher,
The storage elastic modulus (E ′ ₅₀ ) at 50 ° C. of the cured product of the resin composition is 2.5 × 10 ⁹ [Pa] or more,
The arithmetic average roughness (Ra) of the linear prism surface is 20 nm or less.

In the prism sheet of the present invention, the storage elastic modulus (E ′ ₁₀₀ ) of the cured product of the resin composition at ₁₀₀ ° C. and the storage elastic modulus (E ′ ₃₀ ) of the cured product of the resin composition at 30 ° C. The ratio (E ′ ₃₀ / E ′ ₁₀₀ ) is preferably 0.8 or more and 5.0 or less from the viewpoint of suppressing the change in shape of the prism sheet.

  The optical sheet according to the present invention is characterized by having a reflective layer and a resin layer on the surface side of the prism sheet according to the present invention on which the linear prism is arranged.

  A display device according to the present invention includes the optical sheet according to the present invention, and an image source that projects image light onto the optical sheet.

  The resin composition for a prism sheet according to the present invention contains at least a monofunctional (meth) acrylate and a polyfunctional (meth) acrylate, and the polyfunctional (meth) acrylate has a tricyclodecane skeleton. It contains (meth) acrylate.

  According to the present invention, a prism sheet resin composition capable of forming a prism sheet having a flat surface and suppressed shape change, a prism sheet excellent in optical performance, an optical sheet excellent in transparency and specularity, and A display device including the optical sheet can be provided.

FIG. 1 is a perspective view schematically showing one embodiment of a prism sheet according to the present invention. FIG. 2 is a perspective view schematically showing another embodiment of the prism sheet according to the present invention. FIG. 3 is a cross-sectional view schematically showing a part of the BB ′ cross section of the prism sheet in FIG. FIG. 4 is a perspective view schematically showing one embodiment of an optical sheet according to the present invention. FIG. 5 is a cross-sectional view schematically showing a part of the CC ′ cross-section of the optical sheet in FIG. 4. FIG. 6 is a conceptual diagram showing an embodiment of a display device according to the present invention.

Hereinafter, embodiments and examples of the present invention will be described with reference to the drawings. However, the present invention can be implemented in many different modes, and should not be construed as being limited to the description of the embodiments and examples illustrated below. In addition, the drawings may be schematically represented with respect to the width, thickness, shape, and the like of each part in comparison with actual aspects for the sake of clarity of explanation, but are merely examples, and the interpretation of the present invention is not limited. It is not limited. In addition, in the present specification and each drawing, elements similar to those described above with reference to the previous drawings are denoted by the same reference numerals, and detailed description may be omitted as appropriate. Further, for convenience of explanation, the description may be made using the terms “upper” or “lower”, but the vertical direction may be reversed.
In this specification, when a certain configuration such as a certain member or a certain region is “above (or below)” another configuration such as another member or another region, unless otherwise specified, This includes not only when directly above (or directly below) another configuration, but also when above (or below) another configuration, i.e., another configuration above (or below) another configuration. This includes cases where elements are included.
As used in this specification, the shape and geometric conditions and their degree are specified. For example, terms such as “parallel”, “vertical”, “same”, length and angle values, etc. are strictly Without being bound by meaning, it should be interpreted including the extent to which similar functions can be expected.

In the present invention, light includes electromagnetic waves having wavelengths in the visible and invisible regions, and further includes radiation, and the radiation includes, for example, microwaves and electron beams. Specifically, it means an electromagnetic wave having a wavelength of 5 μm or less and an electron beam.
In the present invention, (meth) acryl represents each of acryl or methacryl, and (meth) acrylate represents each of acrylate or methacrylate.

1. Prism sheet The prism sheet according to the present invention is a prism sheet made of a cured product of a resin composition and having a surface on which a plurality of linear prisms extending in one direction are arranged,
The glass transition temperature (Tg) of the cured product of the resin composition is 100 ° C. or higher,
The storage elastic modulus (E ′ ₅₀ ) at 50 ° C. of the cured product of the resin composition is 2.5 × 10 ⁹ [Pa] or more,
The arithmetic average roughness (Ra) of the linear prism surface is 20 nm or less.

The prism sheet of the present invention will be described with reference to the drawings. 1 and 2 are perspective views schematically showing one embodiment of a prism sheet according to the present invention. 3 is a cross-sectional view schematically showing a part of the BB ′ cross section of the prism sheet in FIG.
As shown in the examples of FIGS. 1 and 2, the prism sheet of the present invention has a surface on which a plurality of linear prisms 1 extending in one direction are arranged in parallel to each other. In the present invention, the direction (arrow A in FIG. 1) parallel to the ridge formed by each linear prism may be simply referred to as the extending direction.
The cross-sectional shape of each linear prism is not particularly limited, and may be an isosceles triangle having the same rising angle as shown in the example of FIG. 1, and the rising angle as shown in the examples of FIGS. Different triangles may be used. Note that the cross-sectional shape of the linear prism refers to a triangle formed by a base position (for example, a and b in FIG. 3) and a vertex (for example, c in FIG. 3) in the cross section of the linear prism. In this specification, when the linear prism is a triangle having different rising angles as shown in the examples of FIGS. 2 and 3, for convenience, the angles of the two angles are α and β (α <β), and the α side The slope forming the corner may be referred to as a first slope, and the slope forming the β-side corner may be referred to as a second slope. In the example of FIG. 3, the length of the perpendicular line from the vertex c to the line segment ab in the linear prism section is defined as the height H of the linear prism.
The plurality of linear prisms are arranged substantially in parallel, and the distance between the vertices of adjacent linear prisms may be referred to as an arrangement pitch P.

  The shapes of the prism surface and the linear prism are appropriately designed according to the use of the prism sheet, and are not particularly limited. For example, in the case of an optical sheet described later, the arrangement pitch P is preferably 100 μm or more and 900 μm or less. The linear prism preferably has a rising angle α of 5 ° to 30 °, a rising angle β of 70 ° to 110 °, a height H of 10 μm to 350 μm, and a rising angle α of It is preferable that the angle is 10 degrees or more and 18 degrees or less, the rising angle β is 90 degrees or less, and the height H is 35 μm or more and 290 μm or less.

As a result of intensive studies, the present inventors have found that when a reflective layer such as a metal layer is formed on the prism surface, the inclined surface on which the reflective layer is formed has high flatness, and a resin that forms a linear prism. As a result, it was found that the specularity of the semi-transmissive metal layer is remarkably improved by selecting a resin having small shrinkage due to temperature change. Since the transflective reflective layer needs to be a thin film, it is greatly affected by the flatness of the prism surface that is the base of the reflective layer. In the prism sheet of the present invention, the linear prism is made of a cured product of the resin composition, and the cured product of the resin composition has a glass transition temperature (Tg) of 100 ° C. or higher, and By selecting and using a cured product having a storage elastic modulus (E ′ ₅₀ ) at 50 ° C. of 2.5 × 10 ⁹ [Pa] or more, a temperature change during the production or use of the prism sheet. Resin shrinkage hardly occurs, the arithmetic average roughness (Ra) of the surface of the linear prism can be 20 nm or less, and a prism sheet with a flat surface and suppressed shape change can be obtained. Therefore, it is possible to form a metal layer having excellent transparency and specularity.

[Glass transition temperature (Tg) of cured product of resin composition]
In the prism sheet of this invention, the glass transition temperature (Tg) of the hardened | cured material of the resin composition which comprises a linear prism is 100 degreeC or more. Since the glass transition temperature is 100 ° C. or higher, the prism sheet can be prevented from being deformed when the prism sheet is manufactured or used, and the prism sheet has excellent optical performance, or the optical sheet has excellent transparency and specularity. Can be obtained. In the present invention, the glass transition temperature of the cured product of the resin composition is preferably 110 ° C. or higher, and more preferably 120 ° C. or higher. On the other hand, the upper limit of the glass transition temperature of the cured product of the resin composition is not particularly limited, but can be, for example, 300 ° C. or lower, and more preferably 200 ° C. or lower from the viewpoint of ease of manufacturing the prism sheet. .
In this invention, the glass transition temperature (Tg) of the hardened | cured material of a resin composition can be measured with the storage elastic modulus mentioned later with the dynamic-viscoelasticity apparatus mentioned later.

[Storage modulus]
In the prism sheet of the present invention, the cured product of the resin composition constituting the prism sheet has a storage elastic modulus (E ′ ₅₀ ) at 50 ° C. of 2.5 × 10 ⁹ [Pa] or more. Since the storage elastic modulus at 50 ° C. is 2.5 × 10 ⁹ [Pa] or more, the damage of the linear prism during the formation of the optical sheet described later and the use of the prism sheet is suppressed, and the transparency and specular reflection are suppressed. An optical sheet having excellent properties can be obtained. In the present invention, it is particularly preferred that E ′ ₅₀ is 2.8 × 10 ⁹ [Pa] or more. On the other hand, the upper limit of the storage elastic modulus is not particularly limited, but can be, for example, 1.0 × 10 ¹⁰ [Pa] or less, and preferably 5.0 × 10 ⁹ [Pa] or less.

In the present invention, the storage elastic modulus (E ′) is measured by the following method in accordance with JIS K7244.
First, the coating film of the resin composition to be measured is sufficiently cured, for example, by light irradiation, etc. to obtain a flat sample having no substrate and having a thickness of 1 mm, a width of 5 mm, and a length of 20 mm.
Next, E ′ (E ′ ₅₀ ) at 50 ° C. is obtained by applying a periodic external force of 25 g at 10 Hz in the length direction of the sample at 50 ° C. and measuring dynamic viscoelasticity. Further, E ′ ₃₀ and E ′ ₁₀₀ described later can be measured in the same manner by changing the temperature at the time of measurement. In addition, as a measuring apparatus, the product made from TA Instruments, dynamic viscoelasticity measuring apparatus RSA-G2, etc. can be used, for example.

Furthermore, in the present invention, the ratio between the storage elastic modulus (E ′ ₁₀₀ ) at 100 ° C. of the cured product of the resin composition constituting the prism sheet and the storage elastic modulus (E ′ ₃₀ ) at 30 ° C. of the prism sheet. (E ′ ₃₀ / E ′ ₁₀₀ ) is preferably 0.8 or more and 5.0 or less.
When E ′ ₃₀ / E ′ ₁₀₀ is 5.0 or less, deformation of the linear prism with respect to temperature change is suppressed, so that change in optical performance of the prism sheet at the time of manufacture and use can be suppressed. In the present invention, E ′ ₃₀ / E ′ ₁₀₀ is preferably 3.0 or less, and more preferably 2.0 or less. On the other hand, the lower limit of E ′ ₃₀ / E ′ ₁₀₀ is not particularly limited, but is usually 0.8 or more and preferably 1.0 or more.

  Further, in the present invention, the indentation hardness of the cured product of the resin composition constituting the prism sheet is preferably 1000 MPa or more, and preferably 1100 MPa or more from the viewpoint of suppressing the damage of the linear prism. More preferred. The indentation hardness can be calculated by pushing a predetermined indenter into the cured product of the resin composition to be measured and measuring a load-displacement curve.

[Arithmetic mean roughness of surface of linear prism (Ra)]
In the prism sheet of the present invention, the arithmetic average roughness (Ra) of the surface of the linear prism is 20 nm or less. When the arithmetic average roughness (Ra) of the surface of the linear prism is 20 nm or less, the surface is flat, the optical performance is excellent, and a flat metal layer can be formed. In the present invention, the arithmetic average roughness (Ra) is preferably 15 nm or less, and the arithmetic average roughness (Ra) is more preferably 12 nm or less.
In the present invention, the arithmetic average roughness (Ra) is the arithmetic average roughness (Ra) defined in JIS B0601 (1994). On the other hand, the lower limit of the arithmetic average roughness (Ra) is not particularly limited, but is, for example, 3 nm or more.
The arithmetic average roughness of the surface of the linear prism can be measured using, for example, a white interferometer, NewView 8000 manufactured by Zygo.

<Other configurations>
The prism sheet of the present invention may have a transparent substrate and other layers as long as the effects of the present invention are not impaired.

The transparent substrate may be appropriately selected from conventionally known transparent substrates used for optical applications, and is not particularly limited. Examples of the material used for the transparent substrate include acetyl cellulose resins such as triacetyl cellulose, polyester resins such as polyethylene terephthalate and polyethylene naphthalate, olefin resins such as polyethylene and polymethylpentene, acrylic resins, Transparent resins such as polyurethane resin, polyether sulfone, polycarbonate, polysulfone, polyether, polyether ketone, acrylonitrile, methacrylonitrile, cycloolefin polymer, cycloolefin copolymer, glass such as soda glass, potash glass, lead glass, Examples thereof include ceramics such as PLZT, inorganic materials such as quartz and fluorite, and composite materials thereof.
The transparent substrate may be supplied in the form of a roll, may not be bent so that it can be wound, but may be bent by applying a load, or may not be bent completely, depending on the application. It can be selected appropriately.
In the present invention, the transparent substrate may be subjected to surface treatment (for example, saponification treatment, glow discharge treatment, corona discharge treatment, ultraviolet (UV) treatment, flame treatment), and a primer layer (adhesive layer). May be formed. The transparent substrate in the present invention refers to those including these surface treatments and primer layers.

The average light transmittance of the transparent substrate is preferably 70% or more, and more preferably 85% or more. Here, the transmittance of the light-transmitting substrate can be measured according to JIS K7361-1 (a test method for the total light transmittance of plastic-transparent material).
The thickness of the transparent substrate may be appropriately selected according to the application, but is preferably 100 μm or more and 2 mm or less, and more preferably 500 μm or more and 1.5 mm or less.

[Prism sheet manufacturing method]
The prism sheet which concerns on this invention is manufactured by hardening a resin composition, The glass transition temperature (Tg) of the hardened | cured material of the said resin composition is 100 degreeC or more, and in 50 degreeC of a prism sheet The storage elastic modulus (E ′ ₅₀ ) in the extending direction is 2.5 × 10 ⁹ [Pa] or more, and the arithmetic average roughness (Ra) of the linear prism surface is 20 nm or less.
For example, a resin composition for a prism sheet, which will be described later, is filled in a mold having a predetermined concavo-convex shape, dried as necessary, and then cured by heating or light irradiation, thereby curing the resin composition. A prism sheet can be obtained.
For light irradiation, ultraviolet rays, visible light, electron beams, ionizing radiation, etc. are mainly used. In the case of ultraviolet curing, ultraviolet rays emitted from light such as an ultra-high pressure mercury lamp, a high pressure mercury lamp, a low pressure mercury lamp, a carbon arc, a xenon arc, and a metal halide lamp are used.
The irradiation amount of the energy ray source is about 50 to 5000 mJ / cm ² as an integrated exposure amount at an ultraviolet wavelength of 365 nm. Moreover, when heating, it processes at the temperature of 40-120 degreeC normally.

The following resin composition for prism sheets is mentioned as an example of the resin composition which can form the prism sheet which satisfy | fills said physical property.
That is, the resin composition for a prism sheet according to the present invention contains at least a monofunctional (meth) acrylate and a polyfunctional (meth) acrylate, and the polyfunctional (meth) acrylate has a tricyclodecane skeleton. It contains (meth) acrylate.
The resin composition for a prism sheet includes a polyfunctional (meth) acrylate having a tricyclodecane skeleton. The tricyclodecane skeleton has a bulky and flexible structure compared to, for example, a benzene ring, etc., so that a cured product having a high elasticity, low shrinkage, and a flat surface can be obtained. It is estimated to be. Moreover, it is estimated that the cured | curing material of a resin composition becomes flexible and highly elastic by using monofunctional (meth) acrylate and polyfunctional (meth) acrylate together.

  The prism sheet resin composition contains at least a monofunctional (meth) acrylate and a polyfunctional (meth) acrylate, and may further contain other components as long as the effects of the present invention are not impaired. It ’s good. Hereinafter, such a resin composition for a prism sheet will be described in detail.

(1) Polyfunctional (meth) acrylate In the resin composition for a prism sheet of the present invention, the polyfunctional (meth) acrylate may contain at least a polyfunctional (meth) acrylate having a tricyclodecane skeleton. In addition, other polyfunctional (meth) acrylates may be contained.
Examples of the polyfunctional (meth) acrylate having a tricyclodecane skeleton include tricyclodecane dimethanol diacrylate and tricyclodecane dimethanol dimethacrylate. In the present invention, the polyfunctional (meth) acrylate is represented by the following chemical formula (1). It is preferable to contain tricyclodecane dimethanol diacrylate.

In the resin composition for a prism sheet of the present invention, the content ratio of the polyfunctional (meth) acrylate having a tricyclodecane skeleton is not particularly limited, but is 5 with respect to 100 parts by mass of the solid content of the resin composition for the prism sheet. The mass is preferably from 60 parts by mass to 60 parts by mass, and more preferably from 10 parts by mass to 50 parts by mass.
In the present invention, solid content refers to the sum of all components other than the solvent contained in the resin composition. For example, even a resin that is liquid at room temperature (20 ° C. to 35 ° C.) is included in the solid content. Shall.

Other polyfunctional (meth) acrylates include, for example, ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, propylene di (meth) acrylate, hexanediol di (meth) acrylate, polyethylene glycol di (meth) ) Acrylate, bisphenol A di (meth) acrylate, tetrabromobisphenol A di (meth) acrylate, bisphenol S di (meth) acrylate, butanediol di (meth) acrylate, di (meth) acrylate phthalate, ethylene oxide modified bisphenol A Di (meth) acrylate, trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate , Tris (acryloxyethyl) isocyanurate, pentaerythritol tetra (meth) acrylate, dipentaerythritol hexa (meth) acrylate, urethane tri (meth) acrylate, ester tri (meth) acrylate, urethane hexa (meth) acrylate, ethylene oxide Examples thereof include modified trimethylolpropane tri (meth) acrylate. Polyfunctional (meth) acrylate can be used individually by 1 type or in combination of 2 or more types.
In the resin composition for a prism sheet of the present invention, the content ratio of other polyfunctional (meth) acrylates is not particularly limited, but is 10 parts by mass or less with respect to 100 parts by mass of the solid content of the resin composition for the prism sheet. Preferably, it is preferably 5 parts by mass or less.

(2) Monofunctional (meth) acrylate The monofunctional (meth) acrylate is not particularly limited, and can be appropriately selected from known ones or used alone or in combination of two or more.
Specific examples of monofunctional (meth) acrylates include methyl (meth) acrylate, hexyl (meth) acrylate, decyl (meth) acrylate, allyl (meth) acrylate, benzyl (meth) acrylate, butoxyethyl (meth) acrylate, butoxy Ethylene glycol (meth) acrylate, cyclohexyl (meth) acrylate, dicyclopentanyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, glycerol (meth) acrylate, glycidyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate , 2-hydroxypropyl (meth) acrylate, isobornyl (meth) acrylate, isodexyl (meth) acrylate, isooctyl (meth) acrylate, lauryl (meth) acrylate , 2-methoxyethyl (meth) acrylate, methoxyethylene glycol (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, phenoxyethyl (meth) acrylate, stearyl (meth) acrylate, dodecyl (meth) acrylate, tridecyl (meth) acrylate , Biphenyloxyethyl acrylate, bisphenol A diglycidyl (meth) acrylate, biphenylyloxyethyl (meth) acrylate, ethylene oxide modified biphenylyloxyethyl (meth) acrylate, bisphenol A epoxy (meth) acrylate, and the like.
In the present invention, it is preferable to contain tetrahydrofurfuryl (meth) acrylate represented by the following chemical formula (2). It is estimated that the tetrahydrofurfuryl acrylate has flexibility and high elasticity due to the five-membered ring structure.

  In the resin composition for a prism sheet of the present invention, the content ratio of the monofunctional (meth) acrylate is not particularly limited, but is 10 parts by mass or more and 40 parts by mass with respect to 100 parts by mass of the solid content of the resin composition for the prism sheet. Or less, more preferably 15 parts by mass or more and 30 parts by mass or less.

Moreover, the resin composition for prism sheets may contain other resin in the range which does not impair the effect of this invention. Other resins can be appropriately selected from conventionally known resins used for forming the prism layer. Among these, isophorone diisocyanate, tolylene diisocyanate, triphenylphosphine, N-dioctylmethylamine, and the like can be given because the restoration property of the prism layer is easily improved.
It is preferable that content of the said other resin is 1 to 8 mass parts with respect to 100 mass parts of total solids of the said composition.

(3) Photopolymerization initiator In order to initiate or accelerate the curing reaction of the (meth) acrylate, a photopolymerization initiator may be appropriately selected and used as necessary. Specific examples of the photopolymerization initiator include, for example, bisacylphosphinoxide, 1-hydroxycyclohexyl phenyl ketone (for example, trade name: Irgacure 184, manufactured by BASF), 2-hydroxy-2-methyl-1-phenylpropane. -1-one, 2,2-dimethoxy-1,2-diphenylethane-1-one, 1- [4- (2-hydroxyethoxy) -phenyl] -2-hydroxy-2-methyl-1-propane-1 -One, 2-methyl-1- [4- (methylthio) phenyl] -2-morpholinopropan-1-one, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butanone-1 2-hydroxy-2-methyl-1-phenyl-propane-1-ketone, 2,4,6-trimethylbenzoyldiphenylphos In'okisaido, phenyl bis (2,4,6-trimethylbenzoyl) - phosphine oxide (e.g., trade name: Lucirin TPO: manufactured by BASF), phenyl (2,4,6-trimethylbenzoyl) ethyl phosphinic acid and the like. These can be used alone or in combination of two or more.

  When using a photoinitiator, content of the said photoinitiator is 0.8-20 mass% normally with respect to the total solid of the resin composition for prism sheets, and 0.9-10 mass% It is preferable that

(4) Solvent In the present invention, the resin composition for the prism sheet may use a solvent from the viewpoint of imparting coatability and the like. In the case of using a solvent, the solvent does not react with each component in the composition, and can be appropriately selected from solvents that can dissolve or disperse each component. Specific examples of such solvents include hydrocarbon solvents such as benzene and hexane, ketone solvents such as methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone, tetrahydrofuran, 1,2-dimethoxyethane, propylene glycol monoethyl ether ( PGME) ether solvents such as chloroform and dichloromethane, halogenated alkyl solvents such as methyl acetate, ethyl acetate, butyl acetate, propylene glycol monomethyl ether acetate and other amide solvents such as N, N-dimethylformamide And sulfoxide solvents such as dimethyl sulfoxide, anone solvents such as cyclohexane, and alcohol solvents such as methanol, ethanol, and propanol, but are not limited thereto. Not to. Moreover, the solvent used for a resin composition may be used individually by 1 type, and the mixed solvent of two or more types of solvents may be sufficient as it.

  When a solvent is used in the resin composition for a prism sheet of the present invention, the content of the solvent is preferably 10% by mass or less and more preferably 5% by mass or less with respect to the total amount of the resin composition. preferable. Furthermore, it is more preferable that the resin composition for a prism sheet of the present invention contains substantially no solvent from the viewpoint of the flatness of the prism sheet surface. When preparing a resin composition for a prism sheet that does not contain a solvent, at least one of the monofunctional (meth) acrylate and the polyfunctional (meth) acrylate is 20 ° C. or higher and 35 ° C. from the viewpoint of coating properties and the like. The compound is preferably a liquid compound in at least a part of the following temperature range.

(5) Other components The resin composition for prism sheets may further contain other components as long as the effects of the present invention are not impaired. Other components include, for example, a surfactant for adjusting wettability, a silane coupling agent for improving adhesion, a stabilizer, an antifoaming agent, a repellency inhibitor, an antioxidant, an anti-aggregation agent, and a viscosity. A preparation agent etc. are mentioned.

  The prism sheet according to the present invention can be suitably used for a backlight or the like of a liquid crystal display device or the like, or can be suitably used for a transflective optical sheet described later.

2. Optical sheet The optical sheet according to the present invention is characterized by having a reflective layer and a resin layer on the side of the prism sheet according to the present invention on which the linear prism is arranged.

The optical sheet of the present invention will be described with reference to the drawings. FIG. 4 is a perspective view schematically showing one embodiment of an optical sheet according to the present invention. FIG. 6 is a cross-sectional view schematically showing a part of a CC ′ cross section of the optical sheet in FIG. 5.
As shown in the example of FIG. 4, in the optical sheet 20 of the present invention, the reflective layer 4 and the resin layer 5 are provided on the prism sheet 10 according to the present invention. In the example of FIGS. 4 and 5, the reflective layer 4 is formed only on the first inclined surface 2. The reflection layer 4 is a transflective layer that reflects a part of incident light and transmits the other. The ratio of the reflectance and transmittance of the reflective layer 4 can be set as appropriate according to the application.
Since the optical sheet of the present invention is excellent in the flatness of the surface of the linear prism, it is excellent in the specularity of the reflective layer even when the total transmittance of the reflective layer is designed to be 80% or more.
The total line transmittance can be measured according to JIS K7361-1 (a test method for the total light transmittance of a plastic-transparent material).

  In the present invention, the reflective layer can be appropriately selected from conventionally known reflective layers having transparency. Examples of the reflective layer include a metal layer, a dielectric layer, and combinations thereof. The reflective layer may be a metal layer or a layer composed of only one layer of a dielectric layer. A multilayer film combining two or more layers may be used.

When a metal layer is used as the reflective layer, the metal forming the metal layer is not particularly limited, but a metal having high light reflectivity is preferable, and for example, aluminum, nickel, silver, and the like are preferable.
The formation method of a metal layer is not specifically limited, A conventionally well-known method can be used. For example, it can be formed by vapor deposition, sputtering, metal foil transfer, or the like.
Especially, it is preferable that the metal layer in the optical sheet of this invention forms an aluminum film by a vapor deposition method from a point with easy manufacture. Although it does not specifically limit as thickness of the said metal layer, In the case of aluminum, it is preferable from a point of coexistence of reflectivity and transparency to adjust to 40-60cm.

Further, when a dielectric layer is used as the reflective layer, the compound forming the dielectric layer can be appropriately selected from conventionally known compounds. Specific examples include silicon oxide (SiO ₂ ), titanium oxide (TiO ₂ ), and zirconium oxide (ZrO ₂ ). In the present invention, when a dielectric layer is used as a reflective layer, it is preferably a multilayer film in which dielectric layers having a large refractive index difference are sequentially laminated. Specifically, a silicon oxide layer and a titanium oxide layer are alternately arranged. Preferred examples include multilayer films laminated on each other and multilayer films obtained by alternately laminating silicon oxide and zirconium oxide. The multilayer film preferably has 3 to 7 layers, and more preferably 5 to 7 layers.

Furthermore, in the optical sheet of the present invention, a resin layer is provided on the reflective layer for the purpose of protecting the reflective layer. The resin layer may be appropriately selected from known resins having transparency. For example, the thing similar to the said resin composition for prism sheets is mentioned as a suitable thing.
The method of forming the resin layer is not particularly limited. For example, the resin layer may be formed by applying the resin composition for forming the resin layer on the reflective layer and curing it as necessary. Two prism sheets are prepared, a reflective layer is formed on one prism sheet, and an optical sheet is formed by overlapping the prism sheet having the reflective layer and the prism surfaces of the other prism sheet. May be.

  Since the optical sheet according to the present invention is an optical sheet excellent in transparency and specularity, it can be particularly preferably used for a display device called a head-up display described later.

3. Display Device A display device according to the present invention includes the optical sheet according to the present invention, and an image source that projects image light onto the optical sheet.
A display device according to the present invention will be described with reference to the drawings. FIG. 6 is a conceptual diagram schematically showing one embodiment of a display device according to the present invention. The display device 100 shown in the example of FIG. 6 includes at least an image source 6 and the optical sheet 20 according to the present invention, and the optical sheet 20 is fixed on a transparent plate 7 such as a windshield of a car. ing.
When the image light B1 emitted from the image source 6 is incident on the optical film 20 according to the present invention, at least a part of the image light is reflected by the reflection layer 4, and the reflected light B2 is delivered to the observer D. On the other hand, at least a part of the light C transmitted through the transparent plate 7 passes through the optical film 20 and is delivered to the observer D. Since the optical film 20 according to the present invention is an optical sheet having excellent transparency and specularity, the display device of the present invention has excellent image clarity and a sufficient transparency.
In the present invention, the configuration of the video source 6 is not particularly limited, and can generally be a configuration known as a video source.

  The present invention is not limited to the above embodiment. The above-described embodiment is an exemplification, and the present invention has any configuration that has substantially the same configuration as the technical idea described in the claims of the present invention and that exhibits the same effects. Are included in the technical scope.

(Example 1 Production of prism sheet A)
(1) A resin composition A containing the following compound was prepared.
・ Tetrahydrofurfuryl acrylate ・ Tricyclodecane dimethanol diacrylate ・ Isophorone diisocyanate ・ 2-hydroxyethyl acrylate ・ Irgacure 184 (photopolymerization initiator)
・ Lucirin TPO (photopolymerization initiator)

(2) The resin composition A was applied to a prism sheet mold, a substrate was placed on the coating film, and irradiated with light to cure the resin composition A. The prism sheet A of Example 1 was obtained by removing from the mold.

(Example 2 Production of prism sheet B)
(1) A resin composition B containing the following compound was prepared.
・ Tetrahydrofurfuryl acrylate ・ Tricyclodecane dimethanol diacrylate ・ Isocyanuric acid ethylene oxide modified acrylate ・ Isophorone diisocyanate ・ 2-hydroxyethyl acrylate ・ Irgacure 184 (photopolymerization initiator)
・ Lucirin TPO (photopolymerization initiator)

(2) A prism sheet B was obtained in the same manner as in (2) of Example 1 except that the resin composition A was changed to the resin composition B in (2) of Example 1.

(Comparative Example 1 Production of Prism Sheet C)
(1) A resin composition C containing the following compound was prepared.
・ Ethylene oxide modified bisphenol A diacrylate ・ Ethylene oxide modified phenoxyethyl acrylate

(2) A prism sheet C was obtained in the same manner as in (2) of Example 1 except that the resin composition A was changed to the resin composition C in (2) of Example 1.

(Comparative Example 2 Production of Prism Sheet D)
A resin composition D containing the following compound was prepared.
・ Benzyl methacrylate ・ Isobonyl methacrylate ・ Pentaerythritol polyfunctional acrylate ・ Isophorone diisocyanate ・ 2-hydroxyethyl acrylate ・ 2-hydroxyethyl methacrylate ・ 1,6-hexanediol ・ 1,5-pentanediol ・ Irgacure 184 (photopolymerization initiator )
・ Irgacure 819 (photopolymerization initiator)

[Evaluation]
(Measurement of glass transition temperature and storage modulus)
The coating films of the resin compositions A to D were each sufficiently cured to form a flat single film having a thickness of 1 mm, a width of 5 mm, and a length of 20 mm without a substrate. Next, using a dynamic viscoelasticity measuring device RSA-G2 (manufactured by TA Instruments), in the tensile mode, the glass transition temperature (Tg) and the storage elastic modulus (E ′ ₃₀ , E ′) at 30 ° C., 50 ° C., and 100 ° C. ₅₀ , E ′ ₁₀₀ ), respectively. The results are shown in Table 1.

(Indentation hardness measurement)
About the prism sheet of an Example and a comparative example, the nanoindentation test was done, respectively and the indentation hardness was measured. The results are shown in Table 1.

(Measurement of shrinkage rate)
About the prism sheet of an Example and a comparative example, the shrinkage | contraction rate was measured based on JISK7152-4, respectively. The results are shown in Table 1.

(Surface roughness measurement)
The surface irregularities of the prism sheets of the examples and comparative examples were measured and the arithmetic average roughness (Ra) was calculated using a white interferometer manufactured by Zygo, New View 8000. The results are shown in Table 1.

(Specularity evaluation)
An aluminum layer was formed on the prism surfaces of the prism sheets of the examples and comparative examples by sputtering. The aluminum layer was confirmed to have a total line transmittance of 80% or more according to JIS K7361-1 (plastic-transparent material total light transmittance test method). Each of the prism surfaces on which the aluminum layer was formed was irradiated with an image from an image source, and the disturbance of reflected light of the image was confirmed. The results are shown in Table 1.
<Evaluation criteria>
○: Disturbance of reflected light was not observed.
X: Disturbance of reflected light was observed.

[Summary of results]
As shown in Table 1, the glass transition temperature (Tg) is 100 ° C. or higher, and the storage elastic modulus (E ′ ₅₀ ) at 50 ° C. is 2.5 × 10 ⁹ [Pa] or higher. It became clear that the prism sheets of Examples 1 and 2 formed using the object can obtain an optical sheet having a flat surface, suppressed shape change, and excellent transparency and specularity.

DESCRIPTION OF SYMBOLS 1 Linear prism 2 1st inclined surface 3 2nd inclined surface 4 Reflective layer 5 Resin layer 6 Image source 7 Transparent plate 10 Prism sheet 20 Optical film 100 Display apparatus A Extension direction B1 Image light B2 Reflected light C of image light Transmitted light D observer P arrangement pitch H linear prism height a, b linear prism base position c linear prism apex α, β linear prism rising angle angle

Claims (5)

A prism sheet comprising a cured product of a resin composition and having a surface on which a plurality of linear prisms extending in one direction are arranged,
The glass transition temperature (Tg) of the cured product of the resin composition is 100 ° C. or higher,
The storage elastic modulus (E ′ ₅₀ ) at 50 ° C. of the cured product of the resin composition is 2.5 × 10 ⁹ [Pa] or more,
The prism sheet whose arithmetic mean roughness (Ra) of the said linear prism surface is 20 nm or less. Ratio (E ′ ₃₀ / E ′) of storage elastic modulus (E ′ ₁₀₀ ) at 100 ° C. of the cured product of the resin composition and storage elastic modulus (E ′ ₃₀ ) at 30 ° C. of the cured product of the resin composition. The prism sheet according to claim 1, wherein ₁₀₀ ) is 0.8 or more and 5.0 or less.   The optical sheet which has a reflection layer and a resin layer in the surface side by which the linear prism of the prism sheet of Claim 1 or 2 is arrange | positioned.   A display device comprising: the optical sheet according to claim 3; and an image source that projects image light onto the optical sheet.   A resin composition for a prism sheet, comprising at least a monofunctional (meth) acrylate and a polyfunctional (meth) acrylate, wherein the polyfunctional (meth) acrylate includes a polyfunctional (meth) acrylate having a tricyclodecane skeleton.