JP2014048528A - Laminate, polarizing plate, liquid crystal panel, touch panel sensor, touch panel device, and image display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress occurrence of interference fringes.SOLUTION: A laminate 10 includes an optically transmissive substrate 12, an intermediate layer 13 adjacently laminated on the optically transmissive substrate, and a functional layer 15 adjacently laminated on the intermediate layer on a side opposite the optically transmissive substrate. An in-plane average refractive index nof the optically transmissive substrate, an in-plane average refractive index nof the intermediate layer, and an in-plane average refractive index nof the functional layer satisfy either a condition (a): n>nand n<nor a condition (b): n<nand n>n. Thickness t of the intermediate layer, a maximum wavelength λof visible light, and the in-plane average refractive index nof the intermediate layer satisfy a condition (c1): 0<t<λ/(12×n).

Description

  The present invention relates to a laminate, a polarizing plate, a liquid crystal panel, a touch panel sensor, a touch panel device, and an image display device.

  The image display surface of an image display device such as a liquid crystal display (LCD), a cathode ray tube display (CRT), a plasma display (PDP), an electroluminescence display (ELD), a field emission display (FED) is usually directly or other The laminated body which has the functional layer expected to exhibit a desired function is provided through the member (for example, touch panel sensor). As a typical functional layer, a hard coat layer intended to improve scratch resistance is exemplified.

  The laminate usually has a light-transmitting substrate that supports the functional layer. In such a laminate, light reflected from the surface of the functional layer and the interface between the functional layer and the light transmissive substrate are reflected due to the difference in refractive index between the light transmissive substrate and the functional layer. There is a problem that a rainbow-colored uneven pattern called an interference fringe occurs due to interference with light.

  As a countermeasure against interference fringes, when the functional layer is formed on the light-transmitting substrate, the components of the composition for the functional layer are infiltrated into the upper portion of the light-transmitting substrate, and the vicinity of the interface with the functional layer in the light-transmitting substrate In addition, a mixed region in which the components of the light transmissive substrate and the components of the functional layer are mixed is performed (for example, see Patent Document 1). According to the mixed region, the refractive index interface between the light transmissive substrate and the functional layer can be blurred. For this reason, by providing the mixed region, it is possible to reduce the reflectance at the interface between the light-transmitting substrate and the functional layer, and to prevent the occurrence of interference fringes.

  However, it is necessary to form a mixed region having a sufficient thickness in order to prevent the occurrence of interference fringes. Also, the mixed area is relatively soft. Accordingly, when a mixed region having a sufficient thickness is formed, the functional layer on the mixed region must be thickened in order to give the laminate a desired hardness. For this reason, in the countermeasure using a mixed area | region, it is necessary to apply | coat the composition for functional layers thickly on a transparent base material, and another problem that a manufacturing cost will raise will arise. Moreover, the light-transmitting substrate that can form the mixed region has high moisture permeability, as represented by the triacetylcellulose substrate. And the base material with high moisture permeability which can form a mixing area | region produces the deformation | transformation which brings about a function fall according to the humidity change of an environment.

  Furthermore, as a recent trend, for example, as disclosed in Patent Document 2, it is possible to eliminate the problem of nitrite by adjusting the retardation, so that the optically transmissive substrate of the antiglare film is not only optically isotropic, but also optical Anisotropic substrates have also been used. However, it is difficult to form a mixed region in a stretched polyester base material that is a typical optically anisotropic base material. In other words, the countermeasure against interference fringes using the mixed region cannot be applied to all the transmissive substrates that can be incorporated into the laminate.

  Moreover, in the laminated body called an anti-glare film, since unevenness | corrugation is formed in the outermost surface (for example, refer patent document 3), external light can be diffused. For this reason, in the laminated body called an anti-glare film, interference fringes can be made invisible by diffusion with unevenness on the outermost surface, and there is no need to provide a mixed region. However, in recent years, it has been demanded to impart brightness to an image observed through an antiglare film. In such a tendency, the unevenness formed on the outermost surface of the antiglare film becomes gentle, and there is a problem that interference fringes are visually recognized even in the antiglare film.

JP 2003-131007 A JP2011-107198A JP 2011-81118 A

  The present invention has been made in consideration of the above points, and an object thereof is to suppress the occurrence of interference fringes on a laminate by a method different from the conventional one.

The first laminate according to the present invention comprises:
A light transmissive substrate;
An intermediate layer laminated on the light transmissive substrate adjacent to the light transmissive substrate;
A functional layer laminated adjacent to the intermediate layer from the side opposite to the light-transmitting substrate;
The average refractive index n ₁ in the plane of the light transmissive substrate, the average refractive index n ₂ in the plane of the intermediate layer, and the average refractive index n ₃ in the plane of the functional layer are:
n ₁ > n ₂ and n ₂ <n ₃ ... condition (a)
n ₁ <n ₂ and n ₂ > n ₃ Condition (b)
Either one of the following conditions (a) or (b)
The thickness t of the intermediate layer, the longest wavelength λ _{max of} visible light, and the average refractive index n ₂ in the plane of the intermediate layer are
0 <t <λ _max / (12 × n ₂ ) Condition (c1)
The following condition (c1) is satisfied.

The second laminate according to the present invention comprises:
A light transmissive substrate;
An intermediate layer laminated on the light transmissive substrate adjacent to the light transmissive substrate;
A functional layer laminated adjacent to the intermediate layer from the side opposite to the light-transmitting substrate;
The average refractive index n ₁ in the plane of the light transmissive substrate, the average refractive index n ₂ in the plane of the intermediate layer, and the average refractive index n ₃ in the plane of the functional layer are:
n ₁ > n ₂ and n ₂ <n ₃ ... condition (a)
n ₁ <n ₂ and n ₂ > n ₃ Condition (b)
Either one of the following conditions (a) or (b)
The thickness t of the intermediate layer, the shortest wavelength λ _min of visible light, the longest wavelength λ _{max of} visible light, and the in-plane average refractive index n ₂ are
0 <t <((λ _min + λ _max ) / 2) / (12 × n ₂ )... Condition (c2)
The following condition (c2) is satisfied.

The third laminate according to the present invention is:
A light transmissive substrate;
An intermediate layer laminated on the light transmissive substrate adjacent to the light transmissive substrate;
A functional layer laminated adjacent to the intermediate layer from the side opposite to the light-transmitting substrate;
The average refractive index n ₁ in the plane of the light transmissive substrate, the average refractive index n ₂ in the plane of the intermediate layer, and the average refractive index n ₃ in the plane of the functional layer are:
n ₁ > n ₂ and n ₂ <n ₃ ... condition (a)
n ₁ <n ₂ and n ₂ > n ₃ Condition (b)
Either one of the following conditions (a) or (b)
The thickness t of the intermediate layer, the shortest wavelength λ _{min of} visible light, and the in-plane average refractive index n ₂ are
0 <t <λ _min / (12 × n ₂ ) Condition (c3)
The following condition (c3) is satisfied.

The fourth laminate according to the present invention is:
A light transmissive substrate;
An intermediate layer laminated on the light transmissive substrate adjacent to the light transmissive substrate;
A functional layer laminated adjacent to the intermediate layer from the side opposite to the light-transmitting substrate;
The average refractive index n ₁ in the plane of the light transmissive substrate, the average refractive index n ₂ in the plane of the intermediate layer, and the average refractive index n ₃ in the plane of the functional layer are:
n ₁ > n ₂ and n ₂ <n ₃ ... condition (a)
n ₁ <n ₂ and n ₂ > n ₃ Condition (b)
Either one of the following conditions (a) or (b)
The thickness t [nm] of the intermediate layer and the refractive index n ₂ of the intermediate layer are
0 <t <555 / (12 × n ₂ ) Condition (c4)
The following condition (c4) is satisfied.

The fifth laminate according to the present invention is:
A light transmissive substrate;
An intermediate layer laminated on the light transmissive substrate adjacent to the light transmissive substrate;
A functional layer laminated adjacent to the intermediate layer from the side opposite to the light-transmitting substrate;
The average refractive index n ₁ in the plane of the light transmissive substrate, the average refractive index n ₂ in the plane of the intermediate layer, and the average refractive index n ₃ in the plane of the functional layer are:
n ₁ > n ₂ and n ₂ <n ₃ ... condition (a)
n ₁ <n ₂ and n ₂ > n ₃ Condition (b)
Either one of the following conditions (a) or (b)
The thickness t [nm] of the intermediate layer and the refractive index n ₂ of the intermediate layer are
0 <t <507 / (12 × n ₂ ) Condition (c5)
The following condition (c5) is satisfied.

The sixth laminate according to the present invention is:
A light transmissive substrate;
An intermediate layer laminated on the light transmissive substrate adjacent to the light transmissive substrate;
A functional layer laminated adjacent to the intermediate layer from the side opposite to the light-transmitting substrate;
The average refractive index n ₁ in the plane of the light transmissive substrate, the average refractive index n ₂ in the plane of the intermediate layer, and the average refractive index n ₃ in the plane of the functional layer are:
n ₁ > n ₂ and n ₂ <n ₃ ... condition (a)
n ₁ <n ₂ and n ₂ > n ₃ Condition (b)
Either one of the following conditions (a) or (b)
The intermediate layer has a thickness of 3 nm to 30 nm.

In any of the first to sixth laminates according to the present invention,
The light-transmitting substrate has in-plane birefringence,
Refractive index n _1x in the slow axis direction that is the direction with the highest refractive index in the plane of the light transmissive substrate, and refractive index in the fast axis direction perpendicular to the slow axis direction of the light transmissive substrate. n _1y , the average refractive index n ₂ in the plane of the intermediate layer, and the average refractive index n ₃ in the plane of the functional layer,
n _1y > n ₂ and n ₂ <n ₃ ... condition (d)
n _1x <n ₂ and n ₂ > n ₃ ... condition (e)
Any one of the following conditions (d) and (e) may be satisfied.

In any of the first to sixth laminates according to the present invention,
The light-transmitting substrate has in-plane birefringence,
The retardation of the light transmissive substrate may be 3000 nm or more.

  In any one of the first to sixth laminates according to the present invention, the light-transmitting substrate may be a polyester substrate.

  In any one of the first to sixth laminates according to the present invention, the functional layer may be a hard coat layer.

  Any one of the first to sixth laminates according to the present invention may further include a second functional layer provided on the side of the functional layer opposite to the intermediate layer.

  In any one of the first to sixth laminates according to the present invention, the second functional layer may be a low refractive index layer having a lower refractive index than the functional layer.

The polarizing plate according to the present invention is
A polarizing element;
1 to 6 according to the present invention.

The liquid crystal display panel according to the present invention comprises:
A liquid crystal display panel comprising any one of the first to sixth laminates according to the present invention or the polarizing plate according to the present invention.

  The image display device according to the present invention is an image display device comprising any one of the first to sixth laminates according to the present invention, the polarizing plate according to the present invention, or the liquid crystal display panel according to the present invention.

The touch panel sensor according to the present invention includes:
Any one of the first to sixth laminates according to the present invention;
A sensor electrode joined to the laminate.

  The touch panel device according to the present invention includes the touch panel sensor according to the present invention.

The manufacturing method of the 1st laminated body by this invention is the following.
A light transmissive substrate;
An intermediate layer laminated on the light transmissive substrate adjacent to the light transmissive substrate;
A method of manufacturing a laminate including a functional layer laminated on the intermediate layer from a side opposite to the light-transmitting substrate, adjacent to the intermediate layer,
Either one of the following conditions (a) and (b) is satisfied, and the following condition (c1) using the longest wavelength λ _max of visible light is satisfied: A step of setting an in-plane average refractive index n ₁ , an in-plane average refractive index n ₂ , an in-plane average refractive index n ₃ , and a thickness t of the intermediate layer.
n ₁ > n ₂ and n ₂ <n ₃ ... condition (a)
n ₁ <n ₂ and n ₂ > n ₃ Condition (b)
0 <t <λ _max / (12 × n ₂ ) Condition (c1)

The method for producing the second laminate according to the present invention comprises:
A light transmissive substrate;
An intermediate layer laminated on the light transmissive substrate adjacent to the light transmissive substrate;
A method of manufacturing a laminate including a functional layer laminated on the intermediate layer from a side opposite to the light-transmitting substrate, adjacent to the intermediate layer,
Either one of the following conditions (a) and (b) is satisfied, and the following condition (c2) using the shortest wavelength λ _min of visible light and the longest wavelength λ _max of visible light is satisfied. The average refractive index n ₁ in the plane of the light-transmitting substrate, the average refractive index n ₂ in the plane of the intermediate layer, the average refractive index n ₃ in the plane of the functional layer, and the thickness of the intermediate layer a step of setting t.
n ₁ > n ₂ and n ₂ <n ₃ ... condition (a)
n ₁ <n ₂ and n ₂ > n ₃ Condition (b)
0 <t <((λ _min + λ _max ) / 2) / (12 × n ₂ )... Condition (c2)

The manufacturing method of the 3rd laminated body by this invention is as follows.
A light transmissive substrate;
An intermediate layer laminated on the light transmissive substrate adjacent to the light transmissive substrate;
A method of manufacturing a laminate including a functional layer laminated on the intermediate layer from a side opposite to the light-transmitting substrate, adjacent to the intermediate layer,
Either of the following conditions (a) and (b) is satisfied, and the following condition (c3) using the shortest wavelength λ _min of visible light is satisfied, A step of setting an in-plane average refractive index n ₁ , an in-plane average refractive index n ₂ , an in-plane average refractive index n ₃ , and a thickness t of the intermediate layer.
n ₁ > n ₂ and n ₂ <n ₃ ... condition (a)
n ₁ <n ₂ and n ₂ > n ₃ Condition (b)
0 <t <λ _min / (12 × n ₂ ) Condition (c3)

The method for producing the fourth laminate according to the present invention includes:
A light transmissive substrate;
An intermediate layer laminated on the light transmissive substrate adjacent to the light transmissive substrate;
A method of manufacturing a laminate including a functional layer laminated on the intermediate layer from a side opposite to the light-transmitting substrate, adjacent to the intermediate layer,
The average refractive index n ₁ in the plane of the light transmissive substrate is satisfied so that either one of the following conditions (a) and (b) is satisfied and the following condition (c4) is satisfied: A step of setting an average refractive index n ₂ in the plane of the intermediate layer, an average refractive index n ₃ in the plane of the functional layer, and a thickness t [nm] of the intermediate layer.
n ₁ > n ₂ and n ₂ <n ₃ ... condition (a)
n ₁ <n ₂ and n ₂ > n ₃ Condition (b)
0 <t <555 / (12 × n ₂ ) Condition (c4)

The fifth laminate production method according to the present invention comprises:
A light transmissive substrate;
An intermediate layer laminated on the light transmissive substrate adjacent to the light transmissive substrate;
A method of manufacturing a laminate including a functional layer laminated on the intermediate layer from a side opposite to the light-transmitting substrate, adjacent to the intermediate layer,
The average refractive index n ₁ in the plane of the light transmissive substrate is satisfied so that either one of the following conditions (a) and (b) is satisfied and the following condition (c5) is satisfied: A step of setting an average refractive index n ₂ in the plane of the intermediate layer, an average refractive index n ₃ in the plane of the functional layer, and a thickness t [nm] of the intermediate layer.
n ₁ > n ₂ and n ₂ <n ₃ ... condition (a)
n ₁ <n ₂ and n ₂ > n ₃ Condition (b)
0 <t <507 / (12 × n ₂ ) Condition (c5)

The sixth method for producing a laminate according to the present invention includes:
A light transmissive substrate;
An intermediate layer laminated on the light transmissive substrate adjacent to the light transmissive substrate;
A method of manufacturing a laminate including a functional layer laminated on the intermediate layer from a side opposite to the light-transmitting substrate, adjacent to the intermediate layer,
The average refractive index n ₁ in the plane of the light transmissive substrate is satisfied so that either one of the following conditions (a) and (b) is satisfied and the following condition (c6) is satisfied: A step of setting an average refractive index n ₂ in the plane of the intermediate layer, an average refractive index n ₃ in the plane of the functional layer, and a thickness t [nm] of the intermediate layer.
n ₁ > n ₂ and n ₂ <n ₃ ... condition (a)
n ₁ <n ₂ and n ₂ > n ₃ Condition (b)
3 ≦ t ≦ 30 Condition (c6)

The design method of the first laminate according to the present invention includes:
A light transmissive substrate;
An intermediate layer laminated on the light transmissive substrate adjacent to the light transmissive substrate;
A method of designing a laminate including a functional layer laminated adjacent to the intermediate layer from the side opposite to the light-transmitting substrate;
Either one of the following conditions (a) and (b) is satisfied, and the following condition (c1) using the longest wavelength λ _max of visible light is satisfied: A step of setting an in-plane average refractive index n ₁ , an in-plane average refractive index n ₂ , an in-plane average refractive index n ₃ , and a thickness t of the intermediate layer.
n ₁ > n ₂ and n ₂ <n ₃ ... condition (a)
n ₁ <n ₂ and n ₂ > n ₃ Condition (b)
0 <t <λ _max / (12 × n ₂ ) Condition (c1)

The design method of the second laminate according to the present invention is as follows:
A light transmissive substrate;
An intermediate layer laminated on the light transmissive substrate adjacent to the light transmissive substrate;
A method of designing a laminate including a functional layer laminated adjacent to the intermediate layer from the side opposite to the light-transmitting substrate;
Either one of the following conditions (a) and (b) is satisfied, and the following condition (c2) using the shortest wavelength λ _min of visible light and the longest wavelength λ _max of visible light is satisfied. The average refractive index n ₁ in the plane of the light-transmitting substrate, the average refractive index n ₂ in the plane of the intermediate layer, the average refractive index n ₃ in the plane of the functional layer, and the thickness of the intermediate layer a step of setting t.
n ₁ > n ₂ and n ₂ <n ₃ ... condition (a)
n ₁ <n ₂ and n ₂ > n ₃ Condition (b)
0 <t <((λ _min + λ _max ) / 2) / (12 × n ₂ )... Condition (c2)

The third laminate design method according to the present invention includes:
A light transmissive substrate;
An intermediate layer laminated on the light transmissive substrate adjacent to the light transmissive substrate;
A method of designing a laminate including a functional layer laminated adjacent to the intermediate layer from the side opposite to the light-transmitting substrate;
Either of the following conditions (a) and (b) is satisfied, and the following condition (c3) using the shortest wavelength λ _min of visible light is satisfied, A step of setting an in-plane average refractive index n ₁ , an in-plane average refractive index n ₂ , an in-plane average refractive index n ₃ , and a thickness t of the intermediate layer.
n ₁ > n ₂ and n ₂ <n ₃ ... condition (a)
n ₁ <n ₂ and n ₂ > n ₃ Condition (b)
0 <t <λ _min / (12 × n ₂ ) Condition (c3)

A fourth laminate design method according to the present invention includes:
A light transmissive substrate;
An intermediate layer laminated on the light transmissive substrate adjacent to the light transmissive substrate;
A method of designing a laminate comprising: a functional layer laminated adjacent to the intermediate layer from the side opposite to the light-transmitting substrate;
The average refractive index n ₁ in the plane of the light transmissive substrate is satisfied so that either one of the following conditions (a) and (b) is satisfied and the following condition (c4) is satisfied: A step of setting an average refractive index n ₂ in the plane of the intermediate layer, an average refractive index n ₃ in the plane of the functional layer, and a thickness t [nm] of the intermediate layer.
n ₁ > n ₂ and n ₂ <n ₃ ... condition (a)
n ₁ <n ₂ and n ₂ > n ₃ Condition (b)
0 <t <555 / (12 × n ₂ ) Condition (c4)

The fifth laminate design method according to the present invention includes:
A light transmissive substrate;
An intermediate layer laminated on the light transmissive substrate adjacent to the light transmissive substrate;
A method of designing a laminate comprising: a functional layer laminated adjacent to the intermediate layer from the side opposite to the light-transmitting substrate;
The average refractive index n ₁ in the plane of the light transmissive substrate is satisfied so that either one of the following conditions (a) and (b) is satisfied and the following condition (c5) is satisfied: A step of setting an average refractive index n ₂ in the plane of the intermediate layer, an average refractive index n ₃ in the plane of the functional layer, and a thickness t [nm] of the intermediate layer.
n ₁ > n ₂ and n ₂ <n ₃ ... condition (a)
n ₁ <n ₂ and n ₂ > n ₃ Condition (b)
0 <t <507 / (12 × n ₂ ) Condition (c5)

A sixth laminate design method according to the present invention includes:
A light transmissive substrate;
An intermediate layer laminated on the light transmissive substrate adjacent to the light transmissive substrate;
A method of designing a laminate comprising: a functional layer laminated adjacent to the intermediate layer from the side opposite to the light-transmitting substrate;
The average refractive index n ₁ in the plane of the light transmissive substrate is satisfied so that either one of the following conditions (a) and (b) is satisfied and the following condition (c6) is satisfied: A step of setting an average refractive index n ₂ in the plane of the intermediate layer, an average refractive index n ₃ in the plane of the functional layer, and a thickness t [nm] of the intermediate layer.
n ₁ > n ₂ and n ₂ <n ₃ ... condition (a)
n ₁ <n ₂ and n ₂ > n ₃ Condition (b)
3 ≦ t ≦ 30 Condition (c6)

  According to the present invention, generation of interference fringes can be effectively suppressed.

FIG. 1 is a diagram for explaining an embodiment of the present invention and is a diagram showing a layer structure of a laminate. FIG. 2 is a diagram corresponding to FIG. 1 and showing a layer configuration of another example of the laminated body. FIG. 3 is a diagram for explaining a waveform of light reflected in the laminated body. FIG. 4 is a diagram showing a schematic configuration of a polarizing plate including the laminate shown in FIG. FIG. 5 is a diagram showing a schematic configuration of a liquid crystal display panel including the laminate shown in FIG. 6 is a diagram showing a schematic configuration of a display device including the laminate shown in FIG. FIG. 7 is a diagram illustrating a schematic configuration of a touch panel sensor and a touch panel including the stacked body illustrated in FIG. 1.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the drawings attached to the present specification, for the sake of illustration and ease of understanding, the scale, the vertical / horizontal dimension ratio, and the like are appropriately changed and exaggerated from those of the actual product. 1 to 7 are diagrams for explaining an embodiment of the present invention. Among these, FIG. 1 and FIG. 2 are views for explaining a laminated body. FIG. 3 is a diagram for explaining a waveform of light reflected in the laminated body. 4 to 7 are schematic diagrams illustrating configurations of a polarizing plate, a liquid crystal display panel, a touch panel sensor, a touch panel, and a laminate to which the laminate of FIG. 1 is applied.

≪Laminated body≫
<Overall structure of laminate>
First, the whole structure of the laminated body 10 is demonstrated. As shown in FIG. 1, the laminated body 10 includes a laminated base material 11 and a functional layer 15 formed on one surface of the laminated base material 11. The laminated substrate 11 includes a light transmissive substrate 12 and an intermediate layer 13 laminated with the light transmissive substrate 12. In the laminate 10, the intermediate layer 13 is located between the light transmissive substrate 12 and the functional layer 15. That is, the functional layer 15 is laminated on the laminated base material 11 from the intermediate layer 13 side. In the illustrated example, the intermediate layer 13 is formed on one surface of the light transmissive substrate 12 in the laminated substrate 11. That is, the laminate 10 is configured to include three layers of the light transmissive substrate 12, the intermediate layer 13, and the functional layer 15 in this order. The intermediate layer 13 includes the light transmissive substrate 12 and the function. It arrange | positions adjacent to the layer 15 and forms the interface between the transparent base material 12 and the functional layer 15, respectively.

  FIG. 2 shows a laminate as a modification of the laminate shown in FIG. The laminated body 10 shown in FIG. 2 is different from the laminated body of FIG. 1 in that the second functional layer 17 is formed on the surface of the functional layer 15 that does not face the laminated base material 11. In the laminated body 10 shown in FIG. 1, the functional layer 15 may be composed of a hard coat layer formed on one surface of the laminated base material 11. On the other hand, in the laminate 10 shown in FIG. 2, the functional layer 15 is composed of a hard coat layer formed on one surface of the laminated substrate 11, and the second functional layer 17 is a hard coat layer. You may make it comprise from the low-refractive-index layer formed on the surface on the opposite side to the laminated base material 11 of.

The laminated body 10 demonstrated here satisfy | fills at least the following condition (c1) with one of the following conditions (a) and conditions (b).
n ₁ > n ₂ and n ₂ <n ₃ ... condition (a)
n ₁ <n ₂ and n ₂ > n ₃ Condition (b)
0 <t <λ _max / (12 × n ₂ ) Condition (c1)

Here, in the conditions (a) to (c1) and the conditions (c2) to (c6) described later, “n ₁ ” is the average refractive index in the plane of the light transmissive substrate 12, and “n ₂ ” is intermediate The in-plane average refractive index of the layer 13, and “n ₃ ” is the in-plane average refractive index of the functional layer 15. In the condition (c1) and the conditions (c2) to (c6) described later, “λ _max ” is the longest wavelength [nm] of visible light, and “λ _min ” is the shortest wavelength [nm] of visible light. , “T” is the thickness [nm] of the intermediate layer 13. The in-plane average refractive index is an average value of refractive indexes in two directions perpendicular to each other extending along the sheet surface of the sheet-like layer as a target. If the target layer is optically isotropic, the refractive index in each direction along the sheet surface of the layer is the same. On the other hand, if the target layer is optically anisotropic, the refractive index in each direction along the sheet surface of the layer is different.

  The “sheet surface (film surface, plate surface)” is a sheet-like layer that is a target when the target sheet-like (film-like, plate-like) layer or member is viewed as a whole and globally. Or the surface which corresponds with the planar direction of a member is pointed out. In the laminate 10 described as an embodiment, the sheet surface of the light transmissive substrate 12, the sheet surface of the intermediate layer 13, the sheet surface of the functional layer 15, the sheet surface of the second functional layer 17, and the laminated substrate 11. The sheet surface and the sheet surface of the laminate 10 are parallel to each other.

  The refractive index in each direction in the plane of each layer is an Abbe refractometer (NAR-4T manufactured by Atago Co., Ltd.), “Ellipsometer M150” manufactured by JASCO Corporation, “KOBRA-WR” manufactured by Oji Scientific Instruments, etc. Can be measured.

Moreover, the refractive index in each direction within the plane of each layer was obtained by measuring the average reflectance (R) at a wavelength of 380 to 780 nm using a spectrophotometer (UV-3100PC manufactured by Shimadzu Corporation). From the average reflectance (R), it can be specified using the following equation: The average reflectance (R) of the intermediate layer 13 and the functional layer 15 is determined by applying a raw material composition on a 50 μm thick PET without easy adhesion treatment to obtain a cured film having a thickness of 1 to 3 μm. Apply a black vinyl tape (for example, Yamato vinyl tape NO200-38-21 38 mm width) larger than the measurement spot area on the surface (back surface) on which no object is applied to prevent reflection on the back surface. The average reflectance of the film can be measured. The refractive index of the light-transmitting substrate 12 can be measured after a black vinyl tape is similarly applied to the surface opposite to the measurement surface.
R (%) = (1-n) ² / (1 + n) ²

If the target layers 12, 13, 15 are optically isotropic, the in-plane average refractive indexes n ₁ , n ₂ , n ₃ can be measured as follows. . First, the cured film of each layer is scraped off with a cutter or the like to produce a powder sample. Next, the Becke method according to JISK7142 (2008) B method (for powder or granular transparent material) (using a Cargill reagent having a known refractive index, placing the powdered sample on a slide glass or the like, A reagent is dropped into the sample, and the sample is immersed in the reagent.Observation is observed with a microscope, and the bright line generated in the sample outline due to the difference in the refractive index between the sample and the reagent; Can be used as the refractive index of the sample.

  Moreover, the thickness (at the time of hardening) t of the intermediate layer 13 is, for example, an average value of measured values at arbitrary 10 points obtained by observing the cross section of the intermediate layer 13 with an electron microscope (SEM, TEM, STEM). It can be specified as [nm]. When the thickness of the intermediate layer 13 is very thin, it can be measured by recording what was observed at a high magnification as a photograph and further enlarging it. When enlarged, a layer interface line that is very thin enough to be clearly recognized as a boundary line becomes a thick line. In that case, what is necessary is just to measure as a boundary line the center part which divided the thick line width into 2 equal to the width direction.

When the laminate 10 satisfies at least the condition (c1) together with one of the above-described conditions (a) and (b), the occurrence of interference fringes in the laminate 10 can be effectively suppressed. . Here, the interference fringes to be invisible include the reflected light on the surface of the functional layer 15 of the light (light L _{i in} FIG. 3) from the functional layer 15 side toward the stacked body 10 in FIG. It is an interference fringe produced by interference with the reflected light from the substrate 11 (light L _{r in} FIG. 3). Similarly, of the light traveling from the second functional layer 17 side to the stacked body 10 in FIG. 2, the reflected light on the surface of the second functional layer 17 or the interface between the second functional layer 17 and the functional layer 15. Interference fringes generated by interference between the reflected light and the reflected light from the laminated base material 11 are also interference fringes to be invisible. Here, the reflected light from the laminated substrate 11 refers to the reflected light at the interface between the functional layer 15 and the intermediate layer 13 (light L _{r1 in} FIG. 3) and the interface between the intermediate layer 13 and the light transmissive substrate 12. _Is reflected light (light L _{r2 in} FIG. 3).

  As described below, when the condition (c1) is satisfied together with one of the condition (a) and the condition (b), the light of the laminated body 10 is related to light in at least a part of the wavelength range included in the visible light range. It is possible to effectively reduce the intensity of light which is reflected from the laminated base material 11 toward the laminated base material 11 side from the functional layer 15 side and returns to the functional layer 15 side. That is, by reducing the intensity of light that causes interference fringes, interference fringes resulting from light in at least a part of the wavelength region included in the visible light region can be made significantly inconspicuous.

  Examples of a method of making the interference fringes generated in the laminated body invisible include a method of blurring an interface in the laminated body by providing a mixed region and a method of forming irregularities on the surface of the laminated body. However, as described above, in the method of providing the mixed region, it is necessary to increase the thickness of the functional layer in order to ensure the strength of the stacked body 10. For this reason, when this method is adopted, the material cost increases and the manufacturing cost of the laminate 10 increases. Moreover, when the method of forming irregularities on the surface of the laminate 10 is adopted, the image quality of an image observed through the laminate 10 is deteriorated. Specifically, a cloudiness is generated on the screen, the contrast is lowered, and the image is not terrified or bright.

  On the other hand, the laminated body 10 that satisfies the condition (c1) together with one of the conditions (a) and (b) does not need to be provided with a mixed region and further need not increase the thickness of the functional layer. Further, when the intermediate layer 13 is made of, for example, a primer layer such as an easy-adhesion layer, there is no need to provide an additional layer on the laminate 10 only for the purpose of preventing interference fringes, resulting in cost disadvantages. do not do. In addition, it is possible to use a polyester base material for which it is difficult to provide the mixed region as the light transmissive base material 12. The light transmissive substrate 12 made of a polyester substrate is very excellent in terms of cost and stability.

  In addition, in the laminate 10 that satisfies the condition (c1) together with one of the condition (a) and the condition (b), it is not necessary to cause diffusion, so that the generation of interference fringes is effectively prevented while keeping the surface smooth. can do. Therefore, the interference fringes can be made invisible without adversely affecting the image quality of the image observed through the laminate 10. That is, in the laminate 10 that satisfies the condition (c1) together with one of the condition (a) and the condition (b), it is possible to prevent the occurrence of cloudiness and interference fringes while imparting terry shine to the image.

  Here, referring to FIG. 3, the interference fringe invisible function expressed by the laminate 10 that satisfies the condition (c1) together with one of the conditions (a) and (b), in other words, the generation of interference fringes, A function of suppressing the interference fringes from being visually confirmed, and in other words, a function of making the interference fringes inconspicuous will be described.

  When one of the conditions (a) and (b) is satisfied, the light incident on the laminate 10 from the functional layer 15 side is the interface between the functional layer 15 and the intermediate layer 13 and the intermediate layer 13 and the light transmitting group. The free end reflection occurs at one of the interfaces with the material 12, and the fixed end reflection occurs at the other interface. In the laminate 10 shown in FIG. 3, the condition (b) out of the conditions (a) and (b) is satisfied, and light incident on the laminate 10 from the functional layer 15 side The phase is shifted by π [rad] at the fixed end reflection at the interface with the intermediate layer 13, and the phase is maintained at the free end reflection at the interface between the intermediate layer 13 and the light transmissive substrate 12.

In the example illustrated in FIG. 3, a cross section along the normal direction nd of the stacked body 10 is illustrated. In FIG. 3, incident light L _i incident on the laminate 10 from the functional layer 15 side, reflected light L _r1 reflected at the interface between the functional layer 15 and the intermediate layer 13, the intermediate layer 13, and the light-transmitting base material 12 The vibration state at a certain moment is shown with respect to the reflected light L _r2 reflected at the interface and the combined reflected light L _r which is a combination of the reflected light L _r1 and the reflected L _r2 . As shown in FIG. 3, when the xy coordinates are set so that the x-axis extends in the normal direction of the stacked body 10 and the y-axis extends the interface between the functional layer 15 and the intermediate layer 13, each light L _i , L _r1. , L _r2 and L _r are represented by the following equations (1) to (4), respectively. In the following formulas (1) to (4), “λ” is the wavelength [nm] of light.
Y _i = sin ((x × n ₃ / λ) × 2π) (1)
Y _r1 = sin ((x × n ₃ / λ) × 2π) (2)
Y _r2 = -sin (((x × n ₃ / λ) + (2t × n ₂ / λ)) × 2π) Equation (3)
Y _r = −2 · sin (2t × n ₂ × π / λ) cos (((x × n ₃ / λ) + (t × n ₂ / λ)) × 2π) Equation (4)

That is, the intensity of the synthetic reflected light L _r from the laminated base material 11 that causes interference fringes is expressed by “2 · sin (2t · n ₂ · π / λ)” indicating the amplitude of the waveform of the light. The Interference fringes, as a weak intensity of the synthesized reflected light L _r, becomes inconspicuous. Therefore, when the following expression (5) in which the amplitude of the combined reflected light L _r is less than half of the maximum value (“2”) (less than “1”) is satisfied, the interference fringes caused by the light with the wavelength λ are reduced. It is an inferior situation from the viewpoint of making the interference fringes caused by the light of wavelength λ inconspicuous when the following equation (6) in which the amplitude exceeds half of the maximum value is satisfied. It becomes.
t <λ / (12 × n ₂ ) (5)
t> λ / (12 × n ₂ ) (6)
From the above, when the condition (c1) is satisfied together with the condition (b), at least a part of the light in the visible light wavelength region including the light having the longest visible light wavelength is prevented from being visually recognized as interference fringes. It becomes effective in. In other words, the interference fringes can be effectively invisible with respect to at least a part of visible light.

Further, when the condition (c1) is satisfied together with the condition (a) instead of the condition (b), the interference fringes can be effectively invisible with respect to at least a part of the light in the visible light wavelength region. When the condition (a) is satisfied, the light incident on the stacked body 10 from the functional layer 15 side is fixed-end reflected at the interface between the intermediate layer 13 and the light-transmitting substrate 12 and has a phase of π [rad The phase is maintained by reflecting off the free end at the interface between the functional layer 15 and the intermediate layer 13. Therefore, when light whose phase is delayed by π [rad] with respect to the incident light Li in FIG. 3 is incident on the stacked body 10 satisfying the conditions (a) and (c1) from the functional layer 15 side, The reflected light from the material 11 has the same waveform as the reflected light L _r1 , L _r2 , L _r shown in FIG. From this point, it is understood that interference fringes can be effectively invisible for at least a part of visible light even when the condition (c1) is satisfied together with the condition (a) instead of the condition (b).

  From the above, when the condition (c1) is satisfied together with one of the above-mentioned conditions (a) and (b), at least a part of light in the visible light wavelength region including light having the longest visible light wavelength is visually recognized as interference fringes. Can be effectively prevented. In other words, when the condition (c1) is satisfied together with one of the conditions (a) and (b) described above, the interference fringes can be effectively invisible with respect to at least a part of visible light. In other words, when the condition (c1) is satisfied together with one of the above-described conditions (a) and (b), an interference fringe invisible function (a function for making the interference fringe inconspicuous) that can be perceived by the observer is expressed. I can expect that.

Further, from the viewpoint of making the interference fringes invisible, it is also preferable that the following condition (c2) is satisfied together with one of the condition (a) and the condition (b) described above.
n ₁ > n ₂ and n ₂ <n ₃ ... condition (a)
n ₁ <n ₂ and n ₂ > n ₃ Condition (b)
0 <t <((λ _min + λ _max ) / 2) / (12 × n ₂ )... Condition (c2)
When the condition (c2) is satisfied together with one of the condition (a) and the condition (b), the interference fringe invisible function is effectively exhibited for light in a wavelength region that occupies half or more of the visible light region. Can do. In other words, when the condition (c2) is satisfied together with one of the conditions (a) and (b), the interference fringes caused by light in a wavelength region of more than half of the visible light region can be effectively invisible. .

Furthermore, from the viewpoint of making the interference fringes invisible, it is more preferable that the following condition (c3) is satisfied together with one of the above-described conditions (a) and (b).
n ₁ > n ₂ and n ₂ <n ₃ ... condition (a)
n ₁ <n ₂ and n ₂ > n ₃ Condition (b)
0 <t <(λ _min / 2) / (12 × n ₂ ) ... condition (c3)
When the condition (c3) is satisfied together with one of the condition (a) and the condition (b), the interference fringe invisible function can be effectively exhibited for the light in the entire visible light range. That is, when the condition (c3) is satisfied together with one of the conditions (a) and (b), it is possible to effectively prevent the interference fringes of all colors from being visually recognized.

According to the definition of JISZ8120, the longest wavelength λ _max in the visible light wavelength region can be 830 nm, and the shortest wavelength λ _min in the visible light wavelength region can be 360 nm.

From the viewpoint of making the interference fringes invisible, it is also effective to satisfy the following condition (c4) or condition (c5) together with one of the above-described conditions (a) and (b).
n ₁ > n ₂ and n ₂ <n ₃ ... condition (a)
n ₁ <n ₂ and n ₂ > n ₃ Condition (b)
0 <t [nm] <555 / (12 × n ₂ ) Condition (c4)
0 <t [nm] <507 / (12 × n ₂ ) Condition (c5)

  The International Commission on Illumination (CIE) reports that human sensitivity to light in each wavelength range within the visible light range is different. According to the International Commission on Illumination (CIE), the wavelength of light that is most easily felt by humans when adapting to a bright place is 555 nm, and the wavelength of light that is most easily felt by humans when adapting to a dark place is 507 nm. It is. Therefore, when the condition (c4) is satisfied together with one of the condition (a) and the condition (b), the interference fringe invisible function is effectively enabled for light in a wavelength range that is most easily sensed by humans in a bright place. It can be demonstrated. That is, when the condition (c4) is satisfied together with one of the conditions (a) and (b), it is possible to effectively prevent the interference fringes from being visually recognized in a bright place. On the other hand, when the condition (c5) is satisfied together with one of the condition (a) and the condition (b), not only the light in the wavelength range that is most easily sensed by humans in a bright place but also the human beings in a dark place. The interference fringe invisible function can be effectively exhibited even for light in the wavelength range that is most easily sensed. That is, when the condition (c5) is satisfied together with one of the conditions (a) and (b), it is possible to effectively prevent the interference fringes from being visually recognized in both a bright place and a dark place.

In addition, when the present inventors conducted an extensive experiment, when one of the above-described conditions (a) and (b) and the following condition (c6) are satisfied, the interference fringes are visually recognized even when carefully observed. It was possible to very effectively suppress the occurrence.
n ₁ > n ₂ and n ₂ <n ₃ ... condition (a)
n ₁ <n ₂ and n ₂ > n ₃ Condition (b)
3 ≦ t [nm] ≦ 30 Condition (c6)

In addition, not only the above-described equation (5) but also the following equation (5 ′) using the natural number k is satisfied, the situation is advantageous in terms of making the interference fringes caused by the light of wavelength λ inconspicuous. Become. When Expression (5 ′) is satisfied, the optical path of the reflected light L _r2 is only (λ × k) / (2 × n ₂ ) [nm] longer than that when Expression (5) is satisfied. change in the waveform of the synthesized reflected light L _r does not occur. For this reason, when Formula (5 ') is satisfy | filled, the effect similar to the case where Formula (5) is satisfy | filled can be anticipated.
-λ / (12 × n ₂ ) <t- (k × λ) / (2 × n ₂ ) <λ / (12 × n ₂ ) (5 ')
Therefore, when the next condition (c1 ′) is satisfied together with one of the conditions (a) and (b), the condition (c1) is satisfied together with one of the conditions (a) and (b). The same effect can be expected.
-λ _max / (12 × n ₂ ) <t- (k × λ _max ) / (2 × n ₂ ) <λ _max / (12 × n ₂ )
... Condition (c1 ')

For the same reason, the following conditions (c2 ′) to (c5 ′) are satisfied instead of these conditions (c2) to (c5) for the same reason. In addition, it is possible to expect the same effect as when the conditions (c2) to (c5) are satisfied.
-((λ _min + λ _max ) / 2) / (12 × n ₂ ) <
t- (k × ((λ _min + λ _max ) / 2)) / (2 × n ₂ ) <
((λ _min + λ _max ) / 2) / (12 × n ₂ ) Condition (c2 ′)
-λ _min / (12 × n ₂ ) <t- (k × λ _min ) / (2 × n ₂ ) <λ _min / (12 × n ₂ )
... Condition (c3 ')
-555 / (12 × n ₂ ) <t- (k × 555) / (2 × n ₂ ) <555 / (12 × n ₂ ) Condition (c4 ′)
-507 / (12 × n ₂ ) <t- (k × 507) / (2 × n ₂ ) <507 / (12 × n ₂ ) Condition (c5 ′)

  However, satisfying the conditions (c1 ′) to (c5 ′) instead of the conditions (c1) to (c5) means that the thickness t of the intermediate layer 13 is increased. Therefore, from the viewpoint of material cost, it is preferable that the conditions (c1) to (c5) are satisfied rather than the conditions (c1 ′) to (c5 ′).

By the way, as described in the section of the prior art, the light-transmitting substrate 12 may have in-plane birefringence recently. When the light transmissive substrate 12 has an in-plane birefringence, the refractive index in each direction in the plane along the sheet surface of the light transmissive substrate 12 changes. And in order for the interference fringe invisible function mentioned above to be exhibited more effectively, _one of the above-mentioned formulas (a) and (b) is determined by the average refractive index n ₁ in the plane of the light transmissive substrate 12. In addition to being satisfied, it is preferable that one of the following conditions (d) and (e) is satisfied.
n _1y > n ₂ and n ₂ <n ₃ ... condition (d)
n _1x <n ₂ and n ₂ > n ₃ ... condition (e)
Here, “n _1x ” in the condition (e) is a value of the refractive index in the slow axis direction, which is the direction in which the refractive index is the largest in the plane of the light transmissive substrate 12. On the other hand, “n _1y ” in condition (d) is the value of the refractive index in the fast axis direction, which is the direction in which the refractive index is the smallest in the plane of the light transmissive substrate 12.

When one of the formulas (d) and (e) is satisfied, not only the average refractive index n ₁ in the plane of the light transmissive substrate 12 but also all directions in the plane of the light transmissive substrate 12 One of the following conditions (f) and (g) is satisfied by the refractive index n _{arb at} .
n _arb > n ₂ and n ₂ <n ₃ ... condition (f)
n _arb <n ₂ and n ₂ > n ₃ ... condition (g)
When one of the condition (f) and the condition (g) is satisfied, the light of the polarization component that vibrates in the slow axis direction in the plane of the light transmissive substrate 12 and the surface of the light transmissive substrate 12 Both of the polarized light components oscillating in the fast axis direction are reflected at the interface between the functional layer 15 and the intermediate layer 13 under the same conditions with respect to the phase shift, and under the same conditions with respect to the phase shift. Then, the light is reflected at the interface between the intermediate layer 13 and the light transmissive substrate 12. That is, when one of the condition (f) and the condition (g) is satisfied, the light traveling in the laminated body 10 from the functional layer 15 side to the laminated base material 11 side depends on the polarization state of the light. First, free end reflection is performed at one of the interface between the functional layer 15 and the intermediate layer 13 and the interface between the intermediate layer 13 and the light-transmitting substrate 12, and fixed end reflection is performed at the other interface. For this reason, when one of the condition (f) and the condition (g) is satisfied, the above-described interference fringe invisible function is exhibited extremely effectively without depending on the polarization state.

  On the other hand, when one of the condition (a) and the condition (b) is satisfied but both the condition (f) and the condition (g) are not satisfied, the functional layer 15 side to the laminated base material 11 side Depending on the polarization state of the light, part of the light traveling through the laminated body 10 depends on both the interface between the functional layer 15 and the intermediate layer 13 and the interface between the intermediate layer 13 and the light-transmitting substrate 12. Thus, free end reflection or fixed end reflection occurs. The interference fringe invisible function described above cannot be effectively exerted on such light. However, when one of the condition (a) and the condition (b) is satisfied, the laminated base material from the functional layer 15 side even in a situation where both the condition (f) and the condition (g) are not satisfied. The above-described interference fringe invisible function is effectively exerted on more light that travels through the laminate 10 toward the 11 side. That is, when any one of the conditions (c1) to (c6) described above is satisfied together with one of the conditions (a) and (b), the light incident on the stacked body 10 from the functional layer 15 side. Therefore, the interference fringe invisible function described above is mainly exerted, and the interference fringes can be effectively made inconspicuous.

Moreover, from the viewpoint that the above-described interference fringe invisible function can be more effectively exhibited, the average refractive index n ₃ in the plane of the functional layer 15 and the average refractive index n ₁ in the plane of the light transmissive substrate 12 are close to each other. The average refractive index n ₃ in the plane of the functional layer 15 and the average refractive index n ₁ in the plane of the light transmissive substrate 12 are most preferably equal. As a result of repeated studies by the inventors, the interference fringe invisible function was more effectively exhibited when the following condition (h) was satisfied.
| N ₁ −n ₃ | ≦ 0.03... Condition (h)

<Light transmissive substrate>
Next, the light transmissive substrate 12 will be described in detail. The light-transmitting substrate 12 is not particularly limited as long as it has light-transmitting properties. For example, a cellulose acylate substrate, a cycloolefin polymer substrate, a polycarbonate substrate, an acrylate polymer substrate, a polyester substrate, or A glass substrate is mentioned.

  As a cellulose acylate base material, a cellulose triacetate base material and a cellulose diacetate base material are mentioned, for example. As a cycloolefin polymer base material, the base material which consists of polymers, such as a norbornene-type monomer and a monocyclic cycloolefin monomer, is mentioned, for example.

  As a cycloolefin polymer base material, the base material which consists of polymers, such as a norbornene-type monomer and a monocyclic cycloolefin monomer, is mentioned, for example.

  Examples of the polycarbonate substrate include aromatic polycarbonate substrates based on bisphenols (bisphenol A and the like), aliphatic polycarbonate substrates such as diethylene glycol bisallyl carbonate, and the like.

  Examples of the acrylate polymer base material include a poly (meth) methyl acrylate base material, a poly (meth) ethyl acrylate base material, and a (meth) methyl acrylate- (meth) butyl acrylate copolymer base material. Can be mentioned.

  Examples of the polyester base material include at least one of polyethylene terephthalate, polypropylene terephthalate, polyethylene isophthalate, polybutylene terephthalate, poly (1,4-cyclohexylenedimethylene terephthalate), polyethylene naphthalate, and polyethylene-2,6-naphthalate. The base material etc. which are made into a structural component are mentioned.

  Examples of the glass substrate include glass substrates such as soda lime silica glass, borosilicate glass, and alkali-free glass.

The in-plane average refractive index n ₁ of the light transmissive substrate 12 can be 1.40 or more and 1.80 or less.

  Further, the light transmissive substrate 12 preferably has a transmittance in the visible light region of 80% or more, and more preferably 84% or more. In addition, the said transmittance | permeability can be measured by JISK7361-1 (The test method of the total light transmittance of a plastic-transparent material).

  Furthermore, the light transmissive substrate 12 may be subjected to surface treatment such as saponification treatment, glow discharge treatment, corona discharge treatment, ultraviolet (UV) treatment, and flame treatment without departing from the spirit of the present invention.

  By the way, the light-transmitting substrate 12 may have an in-plane birefringence. The light-transmitting substrate 12 having an in-plane birefringence is generally excellent in terms of mechanical properties, transparency, stability to heat, and the like, and is extremely advantageous in terms of cost. Hereinafter, the light transmissive substrate 12 having in-plane birefringence will be described.

  The optically anisotropic light-transmitting substrate 12 is advantageous in terms of physical properties and cost. On the other hand, such an optically anisotropic light-transmitting substrate 12 is converted into light by one linearly polarized light component. When the image is superimposed on a display device such as a liquid crystal display panel that forms an image, a non-uniform pattern that is observed as a color pattern called “nizimura” may occur. In order to cope with this nidimra, the light transmissive substrate 12 has a retardation of 3000 nm or more. If it is a light-transmitting base material having a retardation of 3000 nm or more, even if the light-transmitting base material is incorporated in an image display device, it is possible to effectively suppress the occurrence of Nizimura in the display image of the image display device. it can. Although the details of the mechanism that can make NDIMURA invisible are unclear, by giving high retardation to the light-transmitting substrate 12, the light that has caused NDJ has a more continuous spectral distribution, As a result, it is expected that it will no longer be visually recognized as unevenness exhibiting a unique color.

  In addition, by using such a light transmissive substrate 12 having a high retardation, the following effects can be obtained which are superior to those of an optically isotropic substrate such as a triacetyl cellulose substrate that has been widely used conventionally. . When an optically isotropic substrate is superimposed on a display device such as a liquid crystal display panel that forms an image with light of one linearly polarized light component, an observer wearing polarized glasses represented by sunglasses Depending on the direction of the absorption axis, there is a problem that the image on the image display device cannot be observed brightly, and further that the image on the image display device cannot be observed. On the other hand, when using the optically anisotropic light-transmitting substrate 12, in particular, the light-transmitting substrate 12 having a high retardation of 3000 nm or more, compared with the case of using an optically isotropic substrate, polarized light The image could be observed brighter regardless of the direction of the absorption axis of the glasses. In such a phenomenon, the polarization state of the image light projected from the display device is disturbed by the optically anisotropic light-transmitting substrate 12, particularly, the light-transmitting substrate 12 having a high retardation of 3000 nm or more. It is estimated that In recent years, the usage environment of display devices has rapidly diversified, and is widely applied to, for example, portable devices and devices used outdoors. With such diversification of usage modes of the display device, it is expected that a situation in which the observer observes the display device while wearing polarized glasses is expected to occur more frequently. Also from such a tendency, application of the optically anisotropic light-transmitting substrate 12 to the optical film 10 of the light-transmitting substrate 12 having a high retardation of 3000 nm or more, in particular, is very useful.

  The retardation is an index that represents the degree of in-plane birefringence. From the viewpoint of preventing azimuth and thinning, it is more preferably 6000 nm or more and 25000 nm or less, and further preferably 8000 nm or more and 20000 nm or less.

Retardation Re (unit: nm) is the refractive index (n _1x ) in the direction with the highest refractive index (slow axis direction) in the plane of the light transmissive substrate, and the direction (fast phase) perpendicular to the slow axis direction. Using the refractive index (n _1y ) in the axial direction and the thickness d (unit: nm) of the light-transmitting substrate, it is represented by the following formula (7).
Re = (n _1x −n _1y ) × d (7)

Retardation can be set to a measured value by setting the measurement angle to 0 ° and the measurement wavelength to 548.2 nm using, for example, KOBRA-WR manufactured by Oji Scientific Instruments. The retardation can also be obtained by the following method. First, using two polarizing plates, the orientation axis direction of the light-transmitting substrate is obtained, and the refractive indexes (n _1x , n _1y ) of two axes perpendicular to the orientation axis direction are obtained as Abbe refractometers. (NAR-4T manufactured by Atago Co., Ltd.) Here, an axis showing a larger refractive index is defined as a slow axis. Further, the thickness of the light-transmitting substrate is measured using, for example, an electric micrometer (manufactured by Anritsu). Then, using the obtained refractive index, a refractive index difference (n _1x -n _1y ) (hereinafter, n _1x -n _1y is referred to as Δn) is calculated, and this refractive index difference Δn and the light-transmitting substrate The retardation can be obtained by the product of the thickness d (nm).

  From the viewpoint of setting the retardation of the light transmissive substrate 12 to 3000 nm or more, the refractive index difference Δn is preferably 0.05 to 0.20. When the refractive index difference Δn is less than 0.05, the thickness necessary for obtaining the retardation value described above may be increased. On the other hand, if the refractive index difference Δn exceeds 0.20, it is necessary to make the draw ratio excessively high, so that tearing, tearing, etc. are likely to occur, and the practicality as an industrial material may be significantly reduced. More preferably, the lower limit of the refractive index difference Δn is 0.07, and the upper limit of the refractive index difference Δn is 0.15. When the refractive index difference Δn exceeds 0.15, depending on the type of the light-transmitting substrate 12, the durability of the light-transmitting substrate 12 in the wet heat resistance test may be inferior. From the viewpoint of ensuring excellent durability in the heat and humidity resistance test, a more preferable upper limit of the refractive index difference Δn is 0.12.

The refractive index n _1x in the slow axis direction of the light transmissive substrate 12 is preferably 1.60 to 1.80, more preferably 1.65, and more preferably 1.75. is there. Further, the refractive index n _1y in the fast axis direction of the light transmissive substrate 12 is preferably 1.50 to 1.70, more preferably 1.55 and more preferably 1.65. is there. It is more preferable that the refractive index n _1x in the slow axis direction and the refractive index n _1y in the fast axis direction of the light-transmitting substrate 12 are in the above ranges and the above-described relationship of the refractive index difference Δn is satisfied. The inhibitory effect of Nijimura can be obtained.

  The thickness of the light-transmitting substrate 12 having in-plane birefringence is not particularly limited, but can usually be 5 μm or more and 1000 μm or less, and the lower limit of the thickness of the light-transmitting substrate 12 is handling. From the viewpoint of properties and the like, it is preferably 15 μm or more, more preferably 25 μm or more. The upper limit of the thickness of the light transmissive substrate 12 is preferably 80 μm or less from the viewpoint of thinning.

  When a polyester substrate having a retardation of 3000 nm or more is used as the light transmissive substrate 12, the thickness of the polyester substrate is preferably 15 μm or more and 500 μm or less. When the thickness is less than 15 μm, the retardation of the polyester base material cannot be increased to 3000 nm or more, the anisotropy of mechanical properties becomes remarkable, and tearing, tearing, etc. are likely to occur, and the practicality as an industrial material is significantly reduced. There is. On the other hand, when it exceeds 500 μm, the flexibility specific to the polymer film is lowered, and the practicality as an industrial material may be lowered. The minimum with more preferable thickness of the said polyester base material is 50 micrometers, a more preferable upper limit is 400 micrometers, and a still more preferable upper limit is 300 micrometers.

  The light-transmitting substrate 12 having in-plane birefringence is not particularly limited as long as it has a retardation of 3000 nm or more, and is an acrylic substrate, a polyester substrate, a polycarbonate substrate, a cycloolefin polymer group. Materials and the like. Among these, a polyester base material is preferable from the viewpoint of cost and mechanical strength.

  The polyester used for the polyester substrate may be a copolymer of the above-mentioned polyester, and the polyester is the main component (for example, a component of 80 mol% or more), and a small proportion (for example, 20 mol% or less) of other polyesters. It may be blended with a kind of resin. Polyethylene terephthalate or polyethylene-2,6-naphthalate is particularly preferable as the polyester because of good balance between mechanical properties and optical properties. In particular, polyethylene terephthalate is preferable because it is highly versatile and easily available. In the present invention, an optical film capable of producing a liquid crystal display device with high display quality can be obtained even if the film is extremely versatile, such as polyethylene terephthalate. Furthermore, polyethylene terephthalate is excellent in transparency, heat or mechanical properties, can be controlled by stretching, has a large intrinsic birefringence, and can obtain a large retardation relatively easily even when the film thickness is small.

  For example, as a method of obtaining a polyester base material having a retardation of 3000 nm or more, a polyester such as polyethylene terephthalate is melted, and the unstretched polyester extruded and formed into a sheet shape is transversal using a tenter or the like at a temperature equal to or higher than the glass transition temperature. A method of performing a heat treatment after stretching is mentioned. The transverse stretching temperature is preferably 80 to 130 ° C, more preferably 90 to 120 ° C. Further, the transverse draw ratio is preferably 2.5 to 6.0 times, more preferably 3.0 to 5.5 times. When the transverse draw ratio exceeds 6.0 times, the transparency of the resulting polyester base material tends to be lowered, and when the draw ratio is less than 2.5 times, the draw tension becomes small. The birefringence of the material is reduced, and the film thickness for obtaining the desired retardation is increased. Further, when the polyester base material is extruded into a sheet shape, stretching in the flow direction (machine direction), that is, longitudinal stretching may be performed. In this case, from the viewpoint of stably ensuring the value of the refractive index difference Δn within the above-described preferred range, the longitudinal stretching preferably has a stretching ratio of 2 times or less. Instead of longitudinal stretching during extrusion molding, longitudinal stretching may be performed after lateral stretching of the unstretched polyester is performed under the above conditions. Moreover, as processing temperature at the time of the said heat processing, 100-250 degreeC is preferable, More preferably, it is 180-245 degreeC.

  Examples of the method for controlling the retardation of the polyester substrate produced by the above-described method to 3000 nm or more include a method of appropriately setting the draw ratio, the drawing temperature, and the film thickness of the produced polyester substrate. Specifically, for example, the higher the stretching ratio, the lower the stretching temperature, and the thicker the film, the easier it is to obtain high retardation. The lower the stretching ratio, the higher the stretching temperature, and the film thickness. The thinner, the easier it is to obtain low retardation.

<Intermediate layer>
Next, the intermediate layer 13 will be described in detail. The intermediate layer 13 satisfies the above-described conditions regarding the thickness t [nm] and the in-plane average refractive index n ₂ , thereby reflecting the reflected light L _r1 and the intermediate layer at the interface between the functional layer 15 and the intermediate layer 13. 13 reduces the light intensity (amplitude) of the combined reflected light L _{r formed} by superimposing the reflected light L _r2 at the interface between the light transmitting base 12 and the interference fringes caused by the combined reflected light L _r. It suppresses that. The intermediate layer 13 is not particularly limited as long as the above-described conditions regarding the thickness t [nm] and the in-plane average refractive index n ₂ are satisfied.

The intermediate layer 13 may have a function other than suppressing the occurrence of interference fringe by reducing the light intensity of the synthesized reflected light L _r (amplitude). For example, the primer layer may form the intermediate layer 13 by adjusting the thickness and the in-plane average refractive index of the primer layer functioning as an easy adhesion layer as a more specific example. . According to such an example, it is possible to eliminate the necessity of providing a new intermediate layer 13 in the stacked body 10 from the viewpoint of preventing the occurrence of interference fringes. In other words, the layer provided for ensuring easy adhesion and the like can be used for invisible interference fringes, which is very preferable from the viewpoint of the material cost of the laminate 10.

  Therefore, the intermediate layer 13 can be made of the same material as the known primer layer. Specifically, the resin contained in the intermediate layer 13 is, for example, polyurethane resin, polyester resin, polyvinyl chloride resin, polyvinyl acetate resin, vinyl chloride-vinyl acetate copolymer, acrylic resin, polyvinyl alcohol resin. , Polyvinyl acetal resin, copolymer of ethylene and vinyl acetate or acrylic acid, copolymer of ethylene and styrene and / or butadiene, thermoplastic resin such as olefin resin and / or modified resin thereof, photopolymerization It can be composed of at least one of a polymer of a compound and a thermosetting resin such as an epoxy resin.

  The photopolymerizable compound has at least one photopolymerizable functional group. In the present specification, the “photopolymerizable functional group” is a functional group capable of undergoing a polymerization reaction by light irradiation. Examples of the photopolymerizable functional group include ethylenic double bonds such as a (meth) acryloyl group, a vinyl group, and an allyl group. The “(meth) acryloyl group” means to include both “acryloyl group” and “methacryloyl group”. The light irradiated when polymerizing the photopolymerizable compound includes visible light and ionizing radiation such as ultraviolet rays, X-rays, electron beams, α rays, β rays, and γ rays.

  Examples of the photopolymerizable compound include a photopolymerizable monomer, a photopolymerizable oligomer, and a photopolymerizable polymer, and these can be appropriately adjusted and used. As the photopolymerizable compound, a combination of a photopolymerizable monomer and a photopolymerizable oligomer or photopolymerizable polymer is preferable.

  When the functional layer 15 described later is formed using a photopolymerizable compound, a polymerization initiator capable of initiating polymerization of the photopolymerizable compound may be added to the intermediate layer 13 in advance. preferable. Thereby, when hardening the functional layer 15, the intermediate | middle layer 13 and the functional layer 15 can be bridge | crosslinked firmly.

  In order to adjust the refractive index of the intermediate layer 13, fine particles, for example, particles of 100 nm or less may be contained in the resin. As an example, low refractive index particles such as silica and magnesium fluoride may be contained in the intermediate layer in order to reduce the refractive index of the intermediate layer 13, and titanium oxide in order to increase the refractive index of the intermediate layer 13. And metal oxide particles such as zirconium oxide may be contained in the intermediate layer.

The thickness of the intermediate layer 13 can be set so as to satisfy any of the conditions (c1) to (c6) described above from the viewpoint of making the interference fringes invisible. The thickness of the intermediate layer 13 is preferably 3 nm or more from the viewpoint of making the film thickness uniform. On the other hand, the in-plane average refractive index n ₂ of the intermediate layer 13 is set so as to satisfy any one of the conditions (c1) to (c6) together with one of the conditions (a) and (b) described above. For example, it can be 1.40 or more and 1.80 or less.

<Functional layer, second functional layer>
Next, the functional layer 15 and the second functional layer 17 will be described. The functional layer 15 and the second functional layer 17 are layers that are intended to exhibit some function in the laminate 10, and specifically include, for example, hard coat properties, antireflection properties, antistatic properties, or Examples include layers that exhibit functions such as antifouling properties. As already described, the number of functional layers included in the stacked body 10 can be any number of one or more depending on the use of the stacked body. In the laminated body 10 shown in FIG. 1, the functional layer 15 is composed of a hard coat layer formed on one surface of the intermediate layer 13 of the laminated base material 11. Moreover, in the laminated body 10 shown by FIG. 2, while the functional layer 15 is comprised from the hard-coat layer formed on the one surface of the intermediate | middle layer 13, the 2nd functional layer 17 is a hard-coat layer. The intermediate layer 13 is composed of a low refractive index layer formed on a surface opposite to the intermediate layer 13. Hereinafter, the hard coat layer as the functional layer 15 and the low refractive index layer as the second functional layer 17 will be described.

  The hard coat layer is a layer for improving the scratch resistance of the optical film. Specifically, it is determined by a pencil hardness test (4.9 N load) defined in JIS K5600-5-4 (1999). A layer having a hardness equal to or higher than “H” is preferable. As an example, the hard coat layer is obtained by applying a composition for a hard coat layer containing a photopolymerizable compound onto the intermediate layer 13 and drying it, and then applying light such as ultraviolet rays to the coating-like composition for a hard coat layer. To polymerize (crosslink) the photopolymerizable compound. The photopolymerizable compound has at least one photopolymerizable functional group. The definition of “photopolymerizable functional group” is the same as described in the column of the intermediate layer 13.

The hard coat layer obtained by this method is optically isotropic and does not have in-plane birefringence. The in-plane average refractive index n ₃ of the obtained hard coat layer can be 1.45 to 1.65. The film thickness (at the time of curing) of the hard coat layer is 0.1 to 100 μm, preferably 0.5 to 20 μm. The film thickness of the hard coat layer is a value measured by observing the cross section with an electron microscope (SEM, TEM, STEM).

  Examples of the photopolymerizable compound include a photopolymerizable monomer, a photopolymerizable oligomer, and a photopolymerizable polymer, and these can be appropriately adjusted and used. As the photopolymerizable compound, a combination of a photopolymerizable monomer and a photopolymerizable oligomer or photopolymerizable polymer is preferable.

Photopolymerizable monomer The photopolymerizable monomer has a weight average molecular weight of less than 1000. The photopolymerizable monomer is preferably a polyfunctional monomer having two or more photopolymerizable functional groups (that is, bifunctional). In the present specification, the “weight average molecular weight” is a value obtained by dissolving in a solvent such as THF and converting to polystyrene by a conventionally known gel permeation chromatography (GPC) method.

  Examples of the bifunctional or higher monomer include trimethylolpropane tri (meth) acrylate, tripropylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, dipropylene glycol di (meth) acrylate, and pentaerythritol tri (meth). Acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol hexa (meth) acrylate, 1,6-hexanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, ditri Methylolpropane tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, tripentaerythritol octa (meth) acrylate, Lapentaerythritol deca (meth) acrylate, isocyanuric acid tri (meth) acrylate, isocyanuric acid di (meth) acrylate, polyester tri (meth) acrylate, polyester di (meth) acrylate, bisphenol di (meth) acrylate, diglycerin tetra ( (Meth) acrylate, adamantyl di (meth) acrylate, isoboronyl di (meth) acrylate, dicyclopentane di (meth) acrylate, tricyclodecane di (meth) acrylate, ditrimethylolpropane tetra (meth) acrylate, and these are PO, EO And the like modified.

  Among these, from the viewpoint of obtaining an antiglare layer having high hardness, a polyfunctional monomer having three or more functions, such as pentaerythritol triacrylate (PETA), dipentaerythritol hexaacrylate (DPHA), pentaerythritol tetraacrylate (PETTA), di Pentaerythritol pentaacrylate (DPPA) and the like are preferable.

The photopolymerizable oligomer The photopolymerizable oligomer has a weight average molecular weight of 1,000 or more and less than 10,000. The photopolymerizable oligomer is preferably a bifunctional or higher polyfunctional oligomer. Polyfunctional oligomers include polyester (meth) acrylate, urethane (meth) acrylate, polyester-urethane (meth) acrylate, polyether (meth) acrylate, polyol (meth) acrylate, melamine (meth) acrylate, and isocyanurate (meth). Examples include acrylate and epoxy (meth) acrylate.

Photopolymerizable polymer The photopolymerizable polymer has a weight average molecular weight of 10,000 or more, and the weight average molecular weight is preferably 10,000 or more and 80,000 or less, and more preferably 10,000 or more and 40,000 or less. When the weight average molecular weight exceeds 80,000, the viscosity is high, so that the coating suitability is lowered, and the appearance of the obtained optical laminate may be deteriorated. Examples of the polyfunctional polymer include urethane (meth) acrylate, isocyanurate (meth) acrylate, polyester-urethane (meth) acrylate, and epoxy (meth) acrylate.

  In addition to the fine particles and the photopolymerizable compound, a thermoplastic resin, a thermosetting resin, a solvent, and a polymerization initiator may be added to the hard coat layer composition as necessary. Furthermore, the hard coat layer composition includes a conventionally known dispersant, surfactant, antistatic agent depending on the purpose such as increasing the hardness of the hard coat layer, suppressing curing shrinkage, or controlling the refractive index. Agent, silane coupling agent, thickener, anti-coloring agent, coloring agent (pigment, dye), antifoaming agent, leveling agent, flame retardant, UV absorber, adhesion-imparting agent, polymerization inhibitor, antioxidant, surface A modifier, a lubricant, etc. may be added.

  The thermoplastic resin added to the hard coat layer composition is preferably non-crystalline and soluble in an organic solvent (particularly a common solvent capable of dissolving a plurality of polymers and curable compounds). In particular, from the viewpoint of transparency and weather resistance, styrene resins, (meth) acrylic resins, alicyclic olefin resins, polyester resins, cellulose derivatives (cellulose esters, etc.) and the like are preferable.

  The thermosetting resin added to the hard coat layer composition is not particularly limited. For example, phenol resin, urea resin, diallyl phthalate resin, melamine resin, guanamine resin, unsaturated polyester resin, polyurethane resin, epoxy resin. Aminoalkyd resin, melamine-urea cocondensation resin, silicon resin, polysiloxane resin, and the like.

As described above, from the viewpoint that the interference fringe invisible function can be more effectively exhibited, the in-plane average refractive index n ₃ and the light-transmitting base material 12 in-plane average refractive index n ₁ Are preferably adjusted so as to take close values, become equal, or satisfy the condition (h).
| N ₁ −n ₃ | ≦ 0.03... Condition (h)
From the viewpoint of adjusting the refractive index of the functional layer 15, fine particles having a particle diameter of, for example, 100 nm or less may be contained in the functional layer forming composition (hard coat layer forming composition). As an example, low refractive index particles such as silica and magnesium fluoride may be contained in the functional layer in order to reduce the refractive index of the functional ability 15, and in order to increase the refractive index of the functional layer 15, titanium oxide. And metal oxide particles such as zirconium oxide may be contained in the functional layer.

  Next, the low refractive index layer is a layer that plays a role of reducing the reflectance when external light (for example, a fluorescent lamp, natural light, etc.) is reflected on the surface of the laminate 10. The low refractive index layer has a refractive index smaller than that of the hard coat layer and larger than that of air. Specifically, the refractive index of the low refractive index layer is preferably in the range of 1.1 to 2.0, more preferably in the range of 1.2 to 1.8, More preferably, it is in the range of -1.6. When the refractive index of the low refractive index layer is within the above range, reflection on the laminate 10 can be effectively prevented. Further, the refractive index of the low refractive index layer is such that the refractive index is gradually directed toward the refractive index of air from the inner side of the laminated body 10 toward the surface side of the laminated body 10 in the low refractive index layer. May have changed.

  The material used for the low refractive index layer is not particularly limited as long as the low refractive index layer having the above-described refractive index can be formed. For example, the resin material described in the hard coat layer composition described above is used. It is preferable to contain. In addition to the resin material, the low refractive index layer can adjust the refractive index by containing a silicone-containing copolymer, a fluorine-containing copolymer, and fine particles. Examples of the silicone-containing copolymer include a silicone-containing vinylidene copolymer. Specific examples of the fluorine-containing copolymer include a copolymer obtained by copolymerizing a monomer composition containing vinylidene fluoride and hexafluoropropylene. Examples of the fine particles include silica fine particles, acrylic fine particles, styrene fine particles, acrylic styrene copolymer fine particles, and fine particles having voids. The term “fine particles having voids” refers to a structure in which fine particles are filled with gas and / or a porous structure containing gas, and the occupancy ratio of the gas in the fine particles compared to the original refractive index of the fine particles. Means a fine particle whose refractive index decreases in inverse proportion to

  Here, examples are shown in which the functional layer 15 is configured as a hard coat layer and the second functional layer 17 is configured as a low refractive index layer. However, the present invention is not limited to these examples. In addition to at least one of the layer and the low refractive index layer, or in place of at least one of the hard coat layer and the low refractive index layer, a layer having other functions such as an antistatic layer, an antiglare layer, and an antifouling layer is included. You may make it.

  The antistatic layer can be formed, for example, by incorporating an antistatic agent into the hard coat layer composition. As the antistatic agent, conventionally known ones can be used. For example, a cationic antistatic agent such as a quaternary ammonium salt, fine particles such as tin-doped indium oxide (ITO), a conductive polymer, or the like can be used. Can do. When using the said antistatic agent, it is preferable that the content is 1-30 mass% with respect to the total mass of all the solid content.

  The antiglare layer can be formed, for example, by adding an antiglare agent to the hard coat layer composition. The antiglare agent is not particularly limited, and various known inorganic or organic fine particles can be used. The average particle size of the fine particles is not particularly limited, but generally may be about 0.01 to 20 μm. Further, the shape of the fine particles may be any of a spherical shape, an elliptical shape, etc., and preferably a spherical shape.

  The fine particles exhibit antiglare properties and are preferably transparent fine particles. Specific examples of such fine particles include silica beads if they are inorganic, and plastic beads if they are organic. Specific examples of the plastic beads include, for example, styrene beads (refractive index 1.60), melamine beads (refractive index 1.57), acrylic beads (refractive index 1.49), and acrylic-styrene beads (refractive index 1. 54), polycarbonate beads, polyethylene beads and the like.

  The antifouling layer is a layer that plays a role of preventing dirt (fingerprints, water-based or oily inks, pencils, etc.) from adhering to the outermost surface of the liquid crystal display device or being able to wipe off easily even if adhering. is there. Further, by forming the antifouling layer, it is possible to improve the antifouling property and scratch resistance of the liquid crystal display device. The antifouling layer can be formed of a composition containing an antifouling agent and a resin, for example.

  The antifouling agent is mainly intended to prevent contamination of the outermost surface of the liquid crystal display device, and can also impart scratch resistance to the liquid crystal display device. Examples of the antifouling agent include fluorine compounds, silicon compounds, and mixed compounds thereof. More specifically, silane coupling agents having a fluoroalkyl group, such as 2-perfluorooctylethyltriaminosilane, and the like can be mentioned, and those having an amino group can be preferably used. It does not specifically limit as said resin, The resin material illustrated with the above-mentioned composition for hard-coat layers is mentioned.

  The antifouling layer can be formed, for example, on the hard coat layer described above. In particular, it is preferable to form the antifouling layer so as to be the outermost surface. The antifouling layer can be replaced by imparting antifouling performance to the hard coat layer itself, for example.

<About the laminate>
According to the laminate 10 described above as an embodiment, the intermediate layer 13 is provided between the functional layer 15 and the light transmissive substrate 12. Then, the average refractive index n ₁ in the plane of the light transmissive substrate 12, the average refractive index n ₂ in the plane of the intermediate layer 13, the average refractive index n ₃ in the plane of the functional layer 15, and the intermediate layer 13 The thickness t [nm] is adjusted so as to satisfy one of the conditions (a) and (b) described above and at least one of the conditions (c1) to (c6). As a result, the light L _r1 incident on the laminate 10 from the functional layer 15 side and reflected at the interface between the functional layer 15 and the intermediate layer 13 and the reflection at the interface between the intermediate layer 13 and the light transmissive substrate 12 are reflected. the light intensity of the composed by superimposing light L _r2 synthesized reflected light L _r (amplitude) can be reduced effectively. Therefore, interference fringes that can be visually recognized due to interference between light reflected on the surface of the laminate 10 and light reflected inside the laminate 10 can be effectively made inconspicuous.

  Further, by setting the retardation of the light-transmitting substrate 12 to 3000 nm or more, Nizimura can be made inconspicuous. Therefore, according to the laminated body 10 demonstrated here, both a nizimura and an interference fringe can be made effectively inconspicuous. Furthermore, it will be suitable for viewing through sunglasses.

  Furthermore, if the intermediate layer 13 is realized by the primer layer, the above-described useful effects can be ensured without causing a substantial increase in material costs, an increase in manufacturing steps, and the like.

≪Polarizing plate≫
The laminated body 10 can be used by being incorporated in the polarizing plate 20, for example. FIG. 5 is a schematic configuration diagram of a polarizing plate 20 incorporating the laminate 10 shown in FIG. As shown in FIG. 5, the polarizing plate 20 includes a laminate 10, a polarizing element 21, and a protective film 22. The polarizing element 21 is formed on the surface of the laminated substrate 11 opposite to the surface on which the functional layer 15 is formed. The protective film 22 is provided on the surface opposite to the surface on which the laminated body 10 of the polarizing elements 21 is provided. The protective film 22 may be a retardation film.

  Examples of the polarizing element 21 include a polyvinyl alcohol film, a polyvinyl formal film, a polyvinyl acetal film, an ethylene-vinyl acetate copolymer saponified film, which are dyed and stretched with iodine or the like.

≪LCD panel≫
The laminate 10 and the polarizing plate 20 can be used by being incorporated in a liquid crystal display panel. FIG. 5 is a schematic configuration diagram of the liquid crystal display panel 30 in which the laminate 10 shown in FIG. 1 and the polarizing plate 20 shown in FIG. 4 are incorporated.

  The liquid crystal display panel shown in FIG. 5 has a protective film 31, such as a triacetyl cellulose film (TAC film), a polarizing element 32, a retardation film 33, an adhesive, from the light source side (backlight unit side) to the viewer side. The agent layer 34, the liquid crystal cell 35, the adhesive layer 36, the retardation film 37, the polarizing element 21, and the laminate 10 are sequentially laminated. In the liquid crystal cell 35, a liquid crystal layer, an alignment film, an electrode layer, a color filter, and the like are disposed between two glass substrates.

  Examples of the retardation films 33 and 37 include a triacetyl cellulose film and a cycloolefin polymer film. The retardation film 37 may be the same as the protective film 22. Examples of the adhesive constituting the adhesive layers 34 and 36 include a pressure sensitive adhesive (PSA).

≪Image display device≫
The laminate 10, the polarizing plate 20, and the liquid crystal display panel 30 can be used by being incorporated in an image display device. Examples of the image display device include a liquid crystal display (LCD), a cathode ray tube display device (CRT), a plasma display (PDP), an electroluminescence display (ELD), a field emission display (FED), a touch panel, a tablet PC, and electronic paper. Can be mentioned. 6 shows a liquid crystal display as an example of an image display device 40 incorporating the laminate 10 shown in FIG. 1, the polarizing plate 20 shown in FIG. 4, and the liquid crystal display panel 30 shown in FIG. It is a schematic block diagram.

  The image display device 40 shown in FIG. 6 is a liquid crystal display. The image display device 30 includes a backlight unit 41 and a liquid crystal display panel 30 including the laminate 10 that is disposed closer to the viewer than the backlight unit 41. A known backlight unit can be used as the backlight unit 41.

≪Touch panel sensor and touch panel device≫
Moreover, the laminated body 10 mentioned above can comprise a touch panel sensor and a part of touch panel as uses other than the use mentioned above. FIG. 7 is a schematic configuration diagram of the touch panel sensor 50 and the touch panel device 55 in which the laminate 10 illustrated in FIG. 1 is incorporated.

  As shown in FIG. 7, the touch panel sensor 50 includes the laminate 10 and the sensor electrode 51. The sensor electrode 51 is formed on the surface opposite to the surface on which the functional layer 15 of the laminated base material 11 is formed. The touch panel device 55 includes a touch panel sensor 50 and a control device 53 that is electrically connected to the sensor electrode 51 of the touch panel sensor 50. The control device 53 is configured to detect the contact position based on a current value that changes in accordance with the contact position on the functional layer 15.

  The touch panel device 55 shown in FIG. 7 constitutes a surface-type capacitive touch panel as an example. Therefore, the sensor electrode 51 is formed in a planar shape, and the four corners of the sensor electrode 51 are electrically connected to the control device 53. The touch panel device 55 and the touch panel sensor 50 are not limited to the example illustrated in FIG. 7, and may be configured as a projection-type capacitance method or may be configured as a resistance film method.

≪Other uses≫
Furthermore, the laminate 10 described above can be used in various applications where the generation of interference fringes should be avoided. For example, the laminate 10 can be used as a window material for a display unit of a device such as a watch or a meter.

  In order to describe the present invention in detail, examples will be described below, but the present invention is not limited to these descriptions.

<Preparation of functional layer composition>
Each component was mix | blended so that it might become a composition shown below, and the composition for functional layers was obtained.
(Composition for functional layer)
Dipentaerythritol hexaacrylate (DPHA) (manufactured by Nippon Kayaku Co., Ltd.): 35 parts by mass Name “Irgacure 184” (manufactured by BASF Japan): 5 parts by mass / polyether-modified silicone (product name “TSF4460”, manufactured by Momentive Performance Materials): 0.025 parts by mass / toluene: 100 parts by mass / methyl Isobutyl ketone (MIBK): 40 parts by mass The refractive index of the cured coating film formed from the functional layer composition having the above composition was 1.65.

<Preparation of composition for intermediate layer>
Each component was blended to obtain the composition shown below to obtain an intermediate layer composition.
(Composition 1 for intermediate layer)
-Aqueous dispersion of polyester resin (solid content 60%): 28.0 parts by mass-Water: 72.0 parts by mass The refractive index of a cured coating film formed from the intermediate layer composition having the above composition was measured. 1.57.

(Composition 2 for intermediate layer)
-Aqueous dispersion of polyester resin (solid content 60%): 20 parts by mass-Aqueous dispersion of titanium oxide fine particles (solid content 20%): 10 parts by mass-Water: 70 parts by mass By the composition for intermediate layer having the above composition It was 1.70 when the independent refractive index of the formed cured coating film was measured.

Example 1
Molten polyethylene terephthalate was melted at 290 ° C., extruded through a film-forming die, into a sheet form, closely contacted on a water-cooled cooled quenching drum, and cooled to produce an unstretched film. This unstretched film was preheated at 120 ° C. for 1 minute using a biaxial stretching test apparatus (manufactured by Toyo Seiki Co., Ltd.), then stretched at 120 ° C. to a stretch ratio of 3.5 times, and then intermediate layers on both sides The composition 1 was applied uniformly with a roll coater. Next, this coated film was subsequently dried at 95 ° C., and stretched at a stretching ratio of 1.5 times in the direction of 90 ° with respect to the stretching direction, retardation = 4800 nm, film thickness = 80 μm, n _1x = 1.68. , N _1y = 1.62, and a polyester base material having an average refractive index of 1.65 was obtained. The film thickness of the intermediate layer was 20 nm.

Then, the composition for functional layers was apply | coated with the bar coater on the formed intermediate | middle layer, it dried at 70 degreeC for 1 minute, the solvent was removed, and the coating film was formed. Next, the coating film was irradiated with ultraviolet rays at an irradiation amount of 150 mJ / cm ² using an ultraviolet irradiation device [manufactured by Fusion UV System Japan Co., Ltd .: H bulb (trade name)], and the film thickness after drying and curing was 6.0 μm. A functional layer was formed to produce a laminate.

(Example 2)
A laminate of Example 2 was manufactured in the same manner as Example 1 except that the thickness of the intermediate layer was 30 nm.

(Example 3)
A laminate of Example 3 was manufactured in the same manner as Example 1 except that the thickness of the intermediate layer was 40 nm.

Example 4
A laminate of Example 4 was produced in the same manner as Example 1 except that the composition 2 for the intermediate layer was used instead of the composition 1 for the intermediate layer. The film thickness of the intermediate layer was 18 nm.

(Example 5)
A laminate of Example 5 was manufactured in the same manner as Example 4 except that the thickness of the intermediate layer was 30 nm.

(Example 6)
A laminate of Example 6 was manufactured in the same manner as Example 4 except that the thickness of the intermediate layer was 35 nm.

(Comparative Example 1)
A laminate of Comparative Example 1 was manufactured in the same manner as Example 1 except that the film thickness of the intermediate layer was set to 70 nm.

(Comparative Example 2)
A laminate of Comparative Example 2 was manufactured in the same manner as Example 4 except that the thickness of the intermediate layer was set to 70 nm.

(Evaluation of interference fringes)
The presence or absence of interference fringes was evaluated according to the following criteria. The sample was evaluated by reflection observation by painting the opposite side of the coated surface with black ink and applying a three-wavelength fluorescent lamp to the coated surface. Table 1 shows the evaluation results in which the evaluation criteria are set as follows.
A: Carefully observed, but generation of interference fringes could not be visually confirmed.
○: When observed carefully, very thin interference fringes that do not cause a problem in actual use were observed.
X: Interference fringes are clearly observed.

DESCRIPTION OF SYMBOLS 10 Laminated body 11 Laminated base material 12 Light transmissive base material 13 Intermediate | middle layer 15 Functional layer 17 2nd functional layer 19 Sensor electrode 20 Polarizing plate 21 Polarizing element 30 Liquid crystal display panel 40 Image display apparatus 50 Touch panel sensor 51 Sensor electrode 53 Control apparatus 55 Touch panel device

Claims (17)

A light transmissive substrate;
An intermediate layer laminated on the light transmissive substrate adjacent to the light transmissive substrate;
A functional layer laminated adjacent to the intermediate layer from the side opposite to the light-transmitting substrate;
The average refractive index n ₁ in the plane of the light transmissive substrate, the average refractive index n ₂ in the plane of the intermediate layer, and the average refractive index n ₃ in the plane of the functional layer are:
n ₁ > n ₂ and n ₂ <n ₃ ... condition (a)
n ₁ <n ₂ and n ₂ > n ₃ Condition (b)
Either one of the following conditions (a) or (b)
The thickness t of the intermediate layer, the longest wavelength λ _{max of} visible light, and the average refractive index n ₂ in the plane of the intermediate layer are
0 <t <λ _max / (12 × n ₂ ) Condition (c1)
A laminate that satisfies the following condition (c1). A light transmissive substrate;
An intermediate layer laminated on the light transmissive substrate adjacent to the light transmissive substrate;
A functional layer laminated adjacent to the intermediate layer from the side opposite to the light-transmitting substrate;
The average refractive index n ₁ in the plane of the light transmissive substrate, the average refractive index n ₂ in the plane of the intermediate layer, and the average refractive index n ₃ in the plane of the functional layer are:
n ₁ > n ₂ and n ₂ <n ₃ ... condition (a)
n ₁ <n ₂ and n ₂ > n ₃ Condition (b)
Either one of the following conditions (a) or (b)
The thickness t of the intermediate layer, the shortest wavelength λ _min of visible light, the longest wavelength λ _{max of} visible light, and the in-plane average refractive index n ₂ are
0 <t <((λ _min + λ _max ) / 2) / (12 × n ₂ )... Condition (c2)
A laminate that satisfies the following condition (c2). A light transmissive substrate;
An intermediate layer laminated on the light transmissive substrate adjacent to the light transmissive substrate;
A functional layer laminated adjacent to the intermediate layer from the side opposite to the light-transmitting substrate;
The average refractive index n ₁ in the plane of the light transmissive substrate, the average refractive index n ₂ in the plane of the intermediate layer, and the average refractive index n ₃ in the plane of the functional layer are:
n ₁ > n ₂ and n ₂ <n ₃ ... condition (a)
n ₁ <n ₂ and n ₂ > n ₃ Condition (b)
Either one of the following conditions (a) or (b)
The thickness t of the intermediate layer, the shortest wavelength λ _{min of} visible light, and the in-plane average refractive index n ₂ are
0 <t <λ _min / (12 × n ₂ ) Condition (c3)
A laminate that satisfies the following condition (c3). A light transmissive substrate;
An intermediate layer laminated on the light transmissive substrate adjacent to the light transmissive substrate;
A functional layer laminated adjacent to the intermediate layer from the side opposite to the light-transmitting substrate;
The average refractive index n ₁ in the plane of the light transmissive substrate, the average refractive index n ₂ in the plane of the intermediate layer, and the average refractive index n ₃ in the plane of the functional layer are:
n ₁ > n ₂ and n ₂ <n ₃ ... condition (a)
n ₁ <n ₂ and n ₂ > n ₃ Condition (b)
Either one of the following conditions (a) or (b)
The thickness t [nm] of the intermediate layer and the refractive index n ₂ of the intermediate layer are
0 <t <555 / (12 × n ₂ ) Condition (c4)
A laminate that satisfies the following condition (c4). A light transmissive substrate;
An intermediate layer laminated on the light transmissive substrate adjacent to the light transmissive substrate;
A functional layer laminated adjacent to the intermediate layer from the side opposite to the light-transmitting substrate;
The average refractive index n ₁ in the plane of the light transmissive substrate, the average refractive index n ₂ in the plane of the intermediate layer, and the average refractive index n ₃ in the plane of the functional layer are:
n ₁ > n ₂ and n ₂ <n ₃ ... condition (a)
n ₁ <n ₂ and n ₂ > n ₃ Condition (b)
Either one of the following conditions (a) or (b)
The thickness t [nm] of the intermediate layer and the refractive index n ₂ of the intermediate layer are
0 <t <507 / (12 × n ₂ ) Condition (c5)
A laminate that satisfies the following condition (c5). A light transmissive substrate;
An intermediate layer laminated on the light transmissive substrate adjacent to the light transmissive substrate;
A functional layer laminated adjacent to the intermediate layer from the side opposite to the light-transmitting substrate;
The average refractive index n ₁ in the plane of the light transmissive substrate, the average refractive index n ₂ in the plane of the intermediate layer, and the average refractive index n ₃ in the plane of the functional layer are:
n ₁ > n ₂ and n ₂ <n ₃ ... condition (a)
n ₁ <n ₂ and n ₂ > n ₃ Condition (b)
Either one of the following conditions (a) or (b)
The laminated body whose thickness of the said intermediate | middle layer is 3 nm or more and 30 nm or less. The light-transmitting substrate has in-plane birefringence,
Refractive index n _1x in the slow axis direction that is the direction with the highest refractive index in the plane of the light transmissive substrate, and refractive index in the fast axis direction perpendicular to the slow axis direction of the light transmissive substrate. n _1y , the average refractive index n ₂ in the plane of the intermediate layer, and the average refractive index n ₃ in the plane of the functional layer,
n _1y > n ₂ and n ₂ <n ₃ ... condition (d)
n _1x <n ₂ and n ₂ > n ₃ ... condition (e)
The laminated body as described in any one of Claims 1-6 which satisfy | fills any one of conditions (d) and (e) which become. The light-transmitting substrate has in-plane birefringence,
The laminate according to any one of claims 1 to 7, wherein the retardation of the light-transmitting substrate is 3000 nm or more.   The laminate according to claim 8, wherein the light-transmitting substrate is a polyester substrate.   The laminate according to any one of claims 1 to 9, wherein the functional layer is a hard coat layer.   The laminated body as described in any one of Claims 1-10 further provided with the 2nd functional layer provided in the opposite side to the said intermediate | middle layer side of the said functional layer.   The laminate according to claim 11, wherein the second functional layer is a low refractive index layer having a lower refractive index than the functional layer. A polarizing element;
A laminate comprising the laminate according to any one of claims 1 to 12.   A liquid crystal display panel provided with the laminated body as described in any one of Claims 1-12, or the polarizing plate of Claim 13.   An image display device comprising the laminate according to any one of claims 1 to 12, the polarizing plate according to claim 13, or the liquid crystal display panel according to claim 14. The laminate according to any one of claims 1 to 12,
A touch panel sensor comprising a sensor electrode joined to the laminate.   A touch panel device comprising the touch panel sensor according to claim 16.

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