JP2018028667A - Laminated substrate, laminate, polarizing plate, liquid crystal display panel and image display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laminated substrate that makes interference fringes less visible while including a light-transmitting substrate having in-plane birefringence.SOLUTION: A laminate substrate 11 is subjected to formation of a functional layer 15 on one surface thereof. The laminate substrate includes a light-transmitting substrate 12 having in-plane birefringence and a refractive index adjusting layer 13 deposited on the light-transmitting substrate and having in-plane birefringence. The refractive index adjusting layer is located between the light-transmitting substrate and the functional layer. A refractive index nin a slow axis direction dx of the light-transmitting substrate, a refractive index nin the slow axis direction dx of the refractive index adjusting layer, a refractive index nin the slow axis direction dx of the functional layer, a refractive index nin a fast axis direction dy of the light-transmitting substrate, a refractive index nin the fast axis direction dy of the refractive index adjusting layer, a refractive index nin the fast axis direction dy of the functional layer satisfy the following relationships: n<n<nor n>n>n, and n<n<nor n>n>n.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a laminated substrate, a laminated body, a polarizing plate, a liquid crystal display panel, and an image display device.

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

  Further, as the light-transmitting substrate of the laminate supporting the functional layer, there is an optically isotropic film having no birefringence, typically a film made of cellulose ester represented by triacetylcellulose. It is used. When a film having birefringence is applied to a display surface of a display device using polarized light such as a liquid crystal display device, there is a problem that unevenness of different colors (hereinafter also referred to as “Nizimura”) is visually recognized. Because it will end up. However, the cellulose ester film has disadvantages that it is inferior in heat-and-moisture resistance and deteriorates polarizing functions such as polarizing function and hue when used in a hot and humid environment.

  From the problem of such a cellulose ester film, it is desired to use a versatile film that is easily available in the market or that can be produced by a simple method as a light-transmitting substrate of a laminate. Various studies have been conducted. For example, in Patent Document 1, a white light emitting diode is used as a light source, and a polymer film having a retardation of 3000 nm to 30000 nm is arranged so that an angle formed by the absorption axis of the polarizing plate and the slow axis of the polymer film is 45 degrees. It is reported that when the screen is observed through a polarizing plate such as sunglasses, good visibility can be secured regardless of the observation angle.

JP2011-107198A

  However, when a hard coat layer is formed on a polyester or polycarbonate film, which is a preferred polymer film in Patent Document 1, it is possible to suppress the occurrence of nitrile, but another problem is that the interference fringes are invisible. It becomes a problem. Here, the interference fringes are partially caused by interference between light reflected on the surface of the functional layer and light reflected once at the interface between the functional layer and the light-transmitting substrate after entering the functional layer. This is a phenomenon in which a rainbow-like color is seen, and is a phenomenon that occurs because the strengthening wavelength changes depending on the viewing direction. This phenomenon is not only difficult to see for the user but may give an unpleasant impression, and improvement is strongly demanded.

  As countermeasures against interference fringes, it is conceivable to reduce the refractive index difference between the functional layer and the light-transmitting substrate and to reduce the reflectance at the interface between the functional layer and the light-transmitting substrate. However, if the light-transmitting substrate has in-plane birefringence and its retardation value is high, trying to avoid the thickness of the light-transmitting substrate becoming thick from the viewpoint of cost and the like, It is necessary to increase the difference in refractive index between the refractive index in the slow axis direction and the refractive index in the fast axis direction in the plane of the light transmissive substrate. Therefore, it is difficult to reduce the refractive index difference between the functional layer and the light-transmitting substrate in both the slow axis direction and the fast axis direction, and as a result, the interference fringes are not sufficiently noticeable. Can not.

  The present invention has been made in consideration of the above points, and an object thereof is to make interference fringes inconspicuous while using a light-transmitting substrate having in-plane birefringence.

The laminated substrate according to the present invention comprises:
A laminated base material in which a functional layer is formed on one surface to form a laminated body,
A light-transmitting substrate having in-plane birefringence;
A refractive index adjusting layer laminated with the light transmissive substrate and having in-plane birefringence, wherein the refractive index adjusting layer is positioned between the light transmissive substrate and the functional layer; With
The refractive index n _1x in the slow axis direction that is the direction in which the refractive index is the largest in the plane of the light transmissive substrate, and the refractive index adjustment layer in the direction parallel to the slow axis direction of the light transmissive substrate. refractive index n _2x, and the refractive index n _3x of the functional layer in the direction parallel with the slow axis direction of the light transmitting substrate,
n _1x <n _2x <n _3x , or n _1x > n _2x > n _3x
Satisfy the relationship
Refractive index n _1y in the fast axis direction orthogonal to the slow axis direction of the light transmissive substrate, and refractive index of the refractive index adjusting layer in a direction parallel to the fast axis direction of the light transmissive substrate. n _2y , and the refractive index n _{3y of the} functional layer in a direction parallel to the fast axis direction of the light transmissive substrate,
n _1y <n _2y <n _3y or n _1y > n _2y > n _3y
Satisfy the relationship.

In the laminated substrate according to the present invention, the refractive index n _2x of the refractive index adjusting layer in a direction parallel to the slow axis direction of the light transmissive substrate, and the fast axis direction of the light transmissive substrate. The refractive index n _2y of the refractive index adjusting layer in the direction parallel to the
n _2x > n _2y
You may make it satisfy | fill the relationship which becomes.

In the laminated substrate according to the present invention, the refractive index n _{1x of} the light transmissive substrate in the slow axis direction, the refractive index n _{1y of} the light transmissive substrate in the _fast axis direction, and the light transmissive substrate. the slow axis direction parallel to the refractive index of the refractive index adjusting layer in the direction n _2x, and the refractive index of the refractive index adjusting layer in the fast axis direction parallel to the direction of the light transmitting substrate n of _2y is (n _1x −n _1y )> (n _2x −n _2y )
You may make it satisfy | fill the relationship which becomes.

  In the laminated base material according to the present invention, when the laminated base material is observed from the normal direction, the refractive index is the largest in the slow axis direction of the light transmissive base material and in the plane of the refractive index adjusting layer. The angle formed by the direction of the slow axis of the refractive index adjusting layer that is the direction may be less than 45 °.

  In the laminated base material according to the present invention, the slow axis direction of the refractive index adjusting layer is a direction in which the slow axis direction of the light transmissive base material is the largest in the plane of the refractive index adjusting layer. It may be parallel.

In the laminated substrate according to the present invention, the refractive index n _1x in the slow axis direction of the light transmissive substrate, the refractive index n _{1y in the fast} axis direction of the light transmissive substrate, and the refractive index adjustment layer The refractive index n _2a in the slow axis direction of the refractive index adjustment layer, which is the direction with the highest refractive index in the plane, and the progression of the refractive index adjustment layer orthogonal to the slow axis direction of the refractive index adjustment layer The refractive index n _2b in the phase axis direction is
(N _1x −n _1y )> (n _2a −n _2b )
You may make it satisfy | fill the relationship which becomes.

In the laminated substrate according to the present invention,
The refractive index n _1x in the slow axis direction of the light transmissive substrate, the refractive index n _2x of the refractive index adjustment layer in a direction parallel to the slow axis direction dx of the light transmissive substrate, and The refractive index n _{3x of the} functional layer in a direction parallel to the slow axis direction of the light transmissive substrate is
n ₂ = (n _2x + n _2y ) / 2 and | n _2x − ((n _1x + n _3x ) / 2) | <| n ₂ − ((n _1x + n _3x ) / 2) |
Satisfy the relationship
The refractive index n _{1y in the fast} axis direction of the light transmissive substrate, the refractive index n _2y of the refractive index adjustment layer in the direction parallel to the _fast axis direction of the light transmissive substrate, and the light The refractive index n _{3y of the} functional layer in a direction parallel to the fast axis direction of the transparent substrate is
n ₂ = (n _2x + n _2y ) / 2 and | n _2y − ((n _1y + n _3y ) / 2) | <| n ₂ − ((n _1y + n _3y ) / 2) |
You may make it satisfy | fill the relationship which becomes.

  The laminated base material according to the present invention may have a retardation of 3000 nm or more.

  In the laminated substrate according to the present invention, the light transmissive substrate may have a retardation of 3000 nm or more.

The laminate according to the present invention comprises:
Any of the laminated substrates according to the invention described above;
A functional layer formed on one surface of the laminated base material,
The refractive index adjustment layer is located between the light transmissive substrate and the functional layer.

  In the laminate according to the present invention, the functional layer may be a hard coat layer.

  The laminate according to the present invention may further include a second functional layer provided on the opposite side of the functional layer from the laminated base material side. In the laminate 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;
Any one of the laminated base materials according to the present invention described above, or any one of the above-described laminated bodies according to the present invention, and the laminated body according to any one of claims 9 to 12.

  The polarizing plate according to the present invention includes any one of the above-described laminated substrates according to the present invention, any of the above-described laminated bodies according to the present invention, or any of the above-described polarizing plates according to the present invention.

  The image display device according to the present invention includes any one of the above-described laminated substrates according to the present invention, any of the above-described laminated bodies according to the present invention, or any of the above-described polarizing plates according to the present invention.

  The touch panel device according to the present invention includes a touch panel sensor and any one of the above-described laminated substrates according to the present invention provided on the touch panel sensor, any of the above-described laminated bodies according to the present invention, or the above-described polarizing plate according to the present invention. It is equipped with either.

  According to the present invention, the refractive index adjusting layer having in-plane birefringence is provided between the functional layer and the light-transmitting substrate having in-plane birefringence. With this refractive index adjusting layer, the reflectance of light once incident on the functional layer can be reduced. Thereby, interference fringes can be made inconspicuous.

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 functional layer. FIG. 3 is a perspective view schematically illustrating the laminated body for explaining the refractive index distribution in the laminated body shown in FIG. 1. FIG. 4 is a diagram for explaining in-plane birefringence in the laminated base material shown in FIG. 1, and is a plan view schematically showing the laminated base material. FIG. 5 is a diagram showing a schematic configuration of a polarizing plate including the laminate shown in FIG. FIG. 6 is a diagram illustrating a schematic configuration of a liquid crystal display panel including the stacked body illustrated in FIG. FIG. 7 is a diagram showing a schematic configuration of a display device including the stacked body shown in FIG.

  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 diagrams for explaining a laminated base material and a laminated body. 3 and 4 are diagrams for explaining the refractive index distributions of the laminated base material and the laminated body. 5-7 is a schematic diagram which shows the structure of a polarizing plate, a liquid crystal display panel, and a laminated body.

≪Laminated substrate and laminated body≫
<Overall structure of laminated substrate and laminated body>
First, the overall configuration of the laminated base material 11 and the laminated body 10 will be described. 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 has a light transmissive substrate 12 and a refractive index adjusting layer 13 laminated with the light transmissive substrate 12. In the laminate 10, the refractive index adjustment 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 refractive index adjustment layer 13 side. In the illustrated example, the refractive index adjustment 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 a light transmissive substrate 12, a refractive index adjusting layer 13, and a functional layer 15 in this order. The refractive index adjusting layer 13 includes a light transmissive group. It arrange | positions adjacent to the material 12 and the functional 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 10 shown in FIG. The laminated body 10 shown in FIG. 2 is different from the laminated body 10 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 light-transmitting substrate 12 included in the laminated substrate 11 is optically anisotropic and has at least in-plane birefringence. The refractive index adjusting layer 13 included in the laminated base material 11 is also optically anisotropic and has at least in-plane birefringence. Therefore, as shown in FIGS. 3 and 4, the refractive index of the light transmissive substrate 12 in the two orthogonal directions along the sheet surface of the sheet-shaped light transmissive substrate 12 is different. Similarly, the refractive index of the refractive index adjusting layer 13 in two orthogonal directions along the sheet surface of the sheet-like refractive index adjusting layer 13 is different.

  Here, “sheet surface (film surface, plate surface)” means the target sheet-like member when the target sheet-like (film-like, plate-like) member is viewed as a whole and globally. It refers to the surface that matches the plane direction. In the example described as one embodiment, the sheet surface of the light transmissive substrate 12, the sheet surface of the refractive index adjustment layer 13, the sheet surface of the functional layer 15, the sheet surface of the laminate substrate 11, and the laminate 10 The sheet surfaces are parallel to each other.

Further, whether or not the light transmissive substrate 12 or the refractive index adjusting layer 13 has in-plane birefringence is determined by whether the light transmissive substrate 12 or the refractive index adjusting layer 13 has a refractive index of 550 nm. In-plane maximum refractive index difference Δn (maximum refractive index difference in two directions along the sheet surface)
Δn ≧ 0.0005
Judgment is made based on whether or not the condition That is, if the maximum refractive index difference Δn in the plane of the light transmissive substrate 12 is 0.0005 or more, the light transmissive substrate 12 has birefringence, and the light transmissive substrate 12 If the maximum refractive index difference Δn in the plane is less than 0.0005, it is determined that the light-transmitting substrate 12 does not have birefringence. Similarly, if the maximum refractive index difference Δn in the plane of the refractive index adjustment layer 13 is 0.0005 or more, the refractive index adjustment layer 13 has birefringence, and the surface of the refractive index adjustment layer 13 If the maximum refractive index difference Δn is less than 0.0005, it is determined that the refractive index adjustment layer 13 does not have birefringence. The birefringence can be measured by setting a measurement angle of 0 ° and a measurement wavelength of 552.1 nm using KOBRA-WR manufactured by Oji Scientific Instruments. At this time, for calculating the birefringence, the film thickness and the average refractive index are required. The film thickness can be measured using, for example, a micrometer (Digimatic Micrometer, manufactured by Mitutoyo Corporation) or an electric micrometer (manufactured by Anritsu Corporation) for a light-transmitting film.
Moreover, when the refractive index adjustment layer 13 is formed as a thin film layer, the TEM cross section is observed, the height of the target layer is measured at least 10 points, and the average value is obtained as the film thickness. The average refractive index can be measured using an Abbe refractometer (NAR-4T manufactured by Atago Co., Ltd.) or an “ellipsometer” manufactured by JASCO Corporation.

  In-plane maximum refractive index difference Δn of TD80UL-M (made by Fuji Film) made of triacetyl cellulose and ZF16-100 (made by Nippon Zeon) made of cycloolefin polymer, which are generally known as isotropic materials. Are determined to be 0.0000375 and 0.00005, respectively, and have no birefringence (isotropic) by the above measurement method.

In the laminated body 10 described here, the refractive index n _1x in the slow axis direction dx, which is the direction in which the refractive index is the largest in the plane of the light transmissive substrate 12, and the slow axis direction dx of the light transmissive substrate 12. The refractive index n _2x of the refractive index adjusting layer in a direction parallel to the refractive index and the refractive index n _3x of the functional layer 15 in a direction parallel to the slow axis direction dx of the light transmissive substrate 12 are
n _1x <n _2x <n _3x , or n _1x > n _2x > n _3x
The condition (a) is satisfied. In addition, the refractive index n _1y in the fast axis direction dy orthogonal to the slow axis direction dx in the plane of the light transmissive substrate 12, and the refraction in the direction parallel to the fast axis direction dy of the light transmissive substrate 11 The refractive index n _2y of the rate adjusting layer 13 and the refractive index n _3y of the functional layer 15 in the direction parallel to the fast axis direction dy of the light-transmitting substrate 12 are
n _1y <n _2y <n _3y or n _1y > n _2y > n _3y
The following condition (b) is satisfied.

  That is, the refractive index adjustment layer 13 is disposed between the functional layer 15 and the light-transmitting base material 12 having birefringence, and the slow axis direction dx and the fast axis direction dy of the light transmitting base material 12. In both directions, the refractive index is changed in two stages. Thereby, between the functional layer 15 and the light transmissive substrate 12 having birefringence, there is no interface in which the refractive index in the slow axis direction dx of the light transmissive substrate 12 greatly changes, In addition, there is no interface where the refractive index of the light transmissive substrate 12 changes greatly in the fast axis direction dy. That is, between the functional layer 15 and the light transmissive substrate 12 having birefringence, the difference in refractive index between the slow axis direction dx and the fast axis direction dy of the light transmissive substrate 12 is small. For this reason, there is only an interface where the reflectivity is low.

  Therefore, it is possible to effectively prevent the light incident on the laminated body 10 from the functional layer 15 side from turning back in the traveling direction due to reflection while traveling toward the light-transmitting substrate 12. Thereby, of the light incident on the laminate 10 from the functional layer 15 side, the light reflected on the surface of the functional layer 15 and the interface between the functional layer 15 and the refractive index adjusting layer 13 or the refractive index adjusting layer 13 and the light. Interference fringes that can be generated by light reflected at the interface with the transmissive substrate 12 can be effectively made inconspicuous.

Further, the refractive index n _2x of the refractive index adjusting layer 13 in the direction parallel to the slow axis direction dx of the light transmissive substrate 12 and the refraction in the direction parallel to the fast axis direction dy of the light transmissive substrate 12. The refractive index n _2y of the rate adjusting layer 13 is
n _2x > n _2y
It is preferable to satisfy the following condition (c). In this case, the refractive index in the slow axis direction dx of the light-transmitting substrate 12 is changed little by little between the functional layer 15 and the light-transmitting substrate 12 having birefringence. In addition, the refractive index in the fast axis direction dy of the light-transmitting substrate 12 can be changed little by little. Thereby, it can prevent more effectively that the light which injected into the laminated body 10 from the side of the functional layer 15 turns advancing direction by reflection, while advancing to the light transmissive base material 12. FIG. As a result, the interference fringes can be made inconspicuous more effectively.

Further, when the condition (c) is satisfied, the refractive index n _1x in the slow axis direction dx of the light transmissive substrate 12, the refractive index n _{1y in the} fast axis direction dy of the light transmissive substrate 12, and light transmission The refractive index n _2x of the refractive index adjusting layer 13 in a direction parallel to the slow axis direction dx of the transparent substrate 12 and the refractive index adjusting layer 13 in a direction parallel to the fast axis direction dy of the light transmissive substrate 12 The refractive index n _2y of
(N _1x -n _1y )> (n _2x -n _2y )
More preferably, the following condition (d) is satisfied. For example, the refractive index n _3x of the functional layer 15 in a direction parallel to the slow axis direction dx of the light transmissive substrate 12 and the functional layer 15 in a direction parallel to the fast axis direction dy of the light transmissive substrate 12. In the case where the refractive index n _3y does not differ greatly, typically, when the functional layer 15 is optically isotropic and does not have birefringence, the conditions (c) and (d) are satisfied. As a result, the refractive index adjustment layer 13 does not exhibit an unnecessarily strong birefringence, and the refractive index is slightly decreased in both the slow axis direction dx and the fast axis direction dy of the light-transmitting substrate 12. It can be changed in different times. Thereby, it can prevent more effectively that the light which entered into the laminated body 10 from the functional layer 15 side turns back the advancing direction by reflection, while advancing to the light transmissive base material 12. As a result, the interference fringes can be made more inconspicuous.

As shown in FIG. 4, when the laminated base material 11 is observed from the normal direction (normal direction to the sheet surface of the laminated base material 11), the slow axis direction dx of the light transmissive base material 12 The angle θ formed by the slow axis direction da of the refractive index adjustment layer 13 which is the direction in which the refractive index is greatest in the plane of the refractive index adjustment layer 13 is preferably less than 45 ° ( Condition (e)). As the angle θ is smaller, the distribution of the refractive index in the plane of the refractive index adjustment layer 13 shows the same tendency as the distribution of the refractive index in the plane of the light transmissive substrate 12. . That is, when the angle θ is less than 45 °, the sheet of the light-transmitting substrate 12 is not limited to the two directions of the slow axis direction dx and the fast axis direction dy of the light-transmitting substrate 12 described above. The refractive index in various directions along the surface gradually changes in two steps without greatly changing between the functional layer 15 and the light-transmitting substrate 12. In particular, when the angle θ is 0 °, that is, when the slow axis direction dx of the light transmissive substrate 12 and the slow axis direction da of the refractive index adjusting layer 13 are parallel (condition (f)). The refractive index in each direction gradually changes twice between the functional layer 15 and the light-transmitting substrate 12 while exhibiting the same tendency as the change in the refractive index in different directions.
Thereby, it is possible to extremely effectively prevent the light incident on the laminated body 10 from the side of the functional layer 15 from turning back due to reflection while traveling to the light-transmitting base material 12. Can be made extremely inconspicuous.

Here, the ellipse drawn on the light transmissive substrate 12 in FIG. 4 is a cross section on the light transmissive substrate 12 for an example of a refractive index ellipsoid showing the refractive index distribution of the light transmissive substrate 12. Is shown.
Similarly, an ellipse drawn on the refractive index adjustment layer 13 in FIG. 4 shows a cross section on the refractive index adjustment layer 13 for an example of a refractive index ellipsoid showing the refractive index distribution of the refractive index adjustment layer 13. ing.

Further, the refractive index n _1x in the slow axis direction dx of the light transmissive substrate 12, the refractive index n _{1y in the} fast axis direction dy of the light transmissive substrate 13, and the slow axis direction da of the refractive index adjustment layer 13. It is preferable that the refractive index n _2a and the refractive index n _{2b in the} fast axis direction db of the refractive index adjusting layer satisfy the condition (g) of (n _1x −n _1y )> (n _2a −n _2b ). When the condition (g) is satisfied, it is possible to prevent the refractive index adjustment layer 13 from having birefringence stronger than necessary as in the case where the condition (d) described above is satisfied. Stripes can be effectively inconspicuous.

Further, along with one or more of the conditions (a) to (g) described above, the in-plane average refractive index n ₁ (n ₁ = (n _1x + n _1y ) / 2) of the light transmissive substrate 12, the refractive index adjustment layer. 13 in-plane average refractive index n ₂ (n ₂ = (n _2x + n _2y ) / 2) and in-plane average refractive index n ₃ (n ₃ = (n _3x + n _3y ) / 2) of the functional layer 15. ,
n ₁ <n ₂ <n ₃ or n ₁ > n ₂ > n ₃
It is preferable to satisfy the following condition (h). When the condition (h) is satisfied, an appropriate birefringence is imparted to the refractive index adjustment layer 13, thereby effectively making the interference fringes inconspicuous.

As a typical example, when the light transmissive substrate 12 is formed from a biaxially stretched polyethylene terephthalate film and the functional layer 15 functions as a hard coat layer, the light transmissive substrate 12 has strong birefringence. In addition, the in-plane average refractive index n _{1 of} the light-transmitting substrate 12 is larger than the in-plane average refractive index n _{3 of the} functional layer 15. In this case, when the condition (h) is satisfied, the refractive index adjustment layer 13 can have birefringence with an appropriate degree according to the degree of birefringence of the functional layer 15, and interference fringes can be obtained. Can be effectively inconspicuous.

Further, along with one or more of the conditions (a) to (h) described above, the refractive index n _1x in the slow axis direction dx of the light transmissive substrate 12 and the refraction in the fast axis direction dy of the light transmissive substrate 12. The refractive index n _1y , the refractive index n _2x of the refractive index adjusting layer 13 in the direction parallel to the slow axis direction dx of the light transmissive substrate 12, the refraction in the direction parallel to the fast axis direction dy of the light transmissive substrate 12 The refractive index n _2y of the rate adjusting layer 13, the refractive index n _3x of the functional layer 15 in a direction parallel to the slow axis direction dx of the light transmissive substrate 12, and the fast axis direction dy of the light transmissive substrate 12. The refractive index n _3y of the functional layer 15 in the direction parallel to the
| n _2x -((n _1x + n _3x )) / 2) | <
| ((n _2x + n _2y ) / 2)-((n _1x + n _3x ) / 2) |
| n _2y -((n _1y + n _3y )) / 2) | <
| ((n _2x + n _2y ) / 2)-((n _1y + n _3y ) / 2) |
It is preferable to satisfy the following condition (i). When the condition (i) is satisfied, the refractive index difference between the refractive index adjustment layer 13 and the light transmissive substrate 12 and the refractive index difference between the refractive index adjustment layer 13 and the functional layer 15 are large. As a result, the difference in refractive index from the light-transmitting substrate 12 to the functional layer 15 can be changed little by little. Thereby, interference fringes can be effectively made inconspicuous.

Incidentally, retardation Re is known as an index representing the degree of in-plane birefringence. Retardation Re uses the refractive index n _max in the slow axis direction where the value is the largest, the refractive index n _min in the fast axis direction where the value is the smallest, and the thickness d (unit: nm) as follows: It is expressed in
Re [nm] = (n _max −n _min ) × d [nm]
As disclosed in Patent Document 1, it is preferable that the laminated base material 11 has a retardation of 3000 nm or more from the viewpoint of preventing nitrite. Further, when the condition (d) and the condition (g) are satisfied, it is more preferable that the light transmissive substrate 12 has a retardation of 3000 nm or more. For example, the retardation can be set to a measured value using a KOBRA-WR manufactured by Oji Scientific Instruments at a measurement angle of 0 ° and a measurement wavelength of 589.3 nm. Further, retardation, using two polarizing plates, determined the orientation direction of the film (the direction of the main axis), the refractive index of the two axes orthogonal to the alignment axis direction (n _x, ny), Abbe It was determined by a refractometer (NAR-4T manufactured by Atago Co., Ltd.). Here, an axis showing a larger refractive index is defined as a slow axis. The film thickness d (nm) was measured using an electric micrometer (manufactured by Anritsu), and the unit was converted to nm. Refractive index difference between _(n x -n _y), than the product of the thickness of the film d (nm), it is also possible to calculate the retardation.

From the viewpoint of setting the retardation of the light transmissive substrate 12 to 3000 nm or more, the difference between the refractive index n _1x in the slow axis direction and the refractive index n _{1y in the} fast axis direction of the light transmissive substrate 12 (hereinafter, “ The refractive index difference Δn ”is preferably 0.05 to 0.20. When the refractive index difference Δn is less than 0.05, the film thickness necessary for obtaining the retardation value described above increases. On the other hand, when the refractive index difference Δn exceeds 0.20, the light transmissive substrate 12 is easily torn and torn, and the practicality as an industrial material is 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. In addition, when the said refractive index difference (DELTA) n exceeds 0.15, depending on the kind of the light transmissive base material 12, durability of the light transmissive base material 12 in a heat-and-moisture resistance test may be inferior. From the viewpoint of securing 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 dx of the light transmissive substrate 12 is preferably 1.60 to 1.80, more preferably 1.65, and more preferably 1.75. It is. In addition, the refractive index n _1y in the fast axis direction dy of the light transmissive substrate 12 is preferably 1.50 to 1.70, more preferably 1.55 and more preferably 1.62. (1.65). The refractive index n _1x in the slow axis direction dx and the refractive index n _1y in the fast axis direction dy of the light transmissive substrate 12 are in the above range, and the above-described relationship of the refractive index difference Δn is satisfied. A more preferable effect of suppressing azimuth can be obtained.

By the way, the refractive index is measured from an average reflectance (R) at a wavelength of 380 to 780 nm using a spectrophotometer (UV-3100PC manufactured by Shimadzu Corporation), and the following is obtained from the obtained average reflectance (R). It is specified using the following formula. The average reflectance (R) of the functional layer 15 is such that the raw material composition is applied on 50 μm thick PET without easy adhesion treatment to form a cured film having a thickness of 1 to 3 μm, and the PET raw material composition is applied. In order to prevent back reflection, a black vinyl tape having a width larger than the measurement spot area (for example, Yamato Vinyl Tape NO200-38-21 38 mm width) is pasted on the surface (back) that was not present, and then the average reflection of each coating film The rate 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. In addition, the refractive index of the refractive index adjusting layer 13 can be measured after a black vinyl tape is pasted on the surface opposite to the measurement surface of the laminated base material 11, that is, the light transmissive base material 12.
R (%) = (1-n) ² / (1 + n) ²

  Further, the refractive index and the birefringence can be measured using the above-mentioned Abbe refractometer or “Ellipsometer M150” manufactured by JASCO Corporation.

Further, as a method for measuring the refractive index n _y in the fast axis direction in the refractive indices n _x and the in-plane slow axis direction in a plane, there is a following method. First, using two polarizing plates, the alignment axis direction (the direction of the main axis, that is, the direction of the slow axis in the plane and the fast axis) of the measurement target (the light transmissive substrate 12 or the refractive index adjustment layer 13). Specific direction). Next, after a black vinyl tape (for example, Yamato vinyl tape No200-38-21 38 mm width) is pasted on the back surface of the measurement object, a spectrophotometer (V7100 type, automatic absolute reflectance measurement unit, VAR-7010).
(Nippon Bunko Co., Ltd.), the polarization measurement condition is S-polarized light, and the reflectance when the vibration direction of the S-polarized light is parallel to the direction of the slow axis of the measurement object is measured five times to obtain an average value. In addition, the average value is calculated by measuring the reflectance when the vibration direction of the S-polarized light and the direction of the fast axis of the measurement object are parallel to each other five times. The refractive index in the slow axis direction of the measurement target is defined as the reflectance R (%) of the following equation, where the average value of the reflectivity when the vibration direction of the S-polarized light is parallel to the slow axis direction of the measurement target. can be obtained n _x, similarly, the average value of the reflectance in the case where the direction of the fast axis of the measuring object and the vibration direction of the S polarized light becomes parallel, as the reflectivity of the following formula R (%) , it is possible to obtain a refractive index n _y in the fast axis direction of the measurement object.
R (%) = (1-n) ² / (1 + n) ²

  Further, as a method of measuring the refractive index of the functional layer 15 after forming the laminate 10, the cured film of each layer is scraped off with a cutter or the like to prepare a powder sample, and the JISK7142 (2008) B method (powder or A Becke method (for a granular transparent material) (using a Cargill reagent having a known refractive index, placing the powdered sample on a glass slide, dropping the reagent on the sample, and immersing the sample in the reagent. Observe the state by microscopic observation, and use the bright line generated in the sample outline due to the difference in the refractive index of the sample and the reagent; the method using the refractive index of the reagent that makes the Becke line invisible visually observable. Can do. Since the refractive index of the light-transmitting substrate 12 and the refractive index adjustment layer 13 varies depending on the direction, the average reflectance is measured by applying the black vinyl tape on the treated surface of the laminated substrate 11 instead of the Becke method. Ask.

<Light transmissive substrate>
Next, the light transmissive substrate 12 of the laminated substrate 11 will be described in detail. The light-transmitting substrate 12 is not particularly limited as long as it is a substrate having visible light transparency having at least an in-plane retardation. For example, examples of the light transmissive substrate 12 include a substrate made of polycarbonate, cycloolefin polymer, acrylic, polyester, or the like. Among these, the polyester base is advantageous in terms of cost and mechanical strength. In the following description, the polyester base material is taken as an example, and the light-transmitting base material 12 having a birefringence in the plane will be described in more detail.

  The material constituting the polyester base material may be a linear saturated polyester synthesized from an aromatic dibasic acid or an ester-forming derivative thereof and a diol or an ester-forming derivative thereof. Specific examples of such polyester include polyethylene terephthalate, polyethylene isophthalate, polybutylene terephthalate, poly (1,4-cyclohexylenedimethylene terephthalate), and polyethylene-2,6-naphthalate. Moreover, the polyester used for the polyester base material may be a copolymer of these polyesters. 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). It may be blended with other types of resins. 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, it is preferably made of polyethylene terephthalate (PET). This is because polyethylene terephthalate is highly versatile and easily available. Furthermore, PET is excellent in transparency, heat or mechanical properties, can control the retardation by stretching, has a large intrinsic birefringence, and can obtain a large retardation relatively easily even when the film thickness is small.

  As a method of obtaining the polyester base material, for example, after melting the polyester such as the material PET and extruding the sheet into a sheet shape using a tenter or the like at a temperature equal to or higher than the glass transition temperature, The method of performing heat processing 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. The treatment temperature during the heat treatment is preferably 100 to 250 ° C, more preferably 180 to 245 ° C.

  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.

  The thickness of the polyester base material is preferably in the range of 15 to 500 μm. When the thickness is less than 15 μm, the retardation of the polyester base material cannot be increased to 3000 nm or more, and the anisotropy of mechanical properties becomes remarkable, and tearing, tearing, and the like easily occur, and the practicality as an industrial material is significantly reduced. Sometimes. On the other hand, if it exceeds 500 μm, the polyester base material is very rigid, the flexibility specific to the polymer film is lowered, and the practicality as an industrial material is also lowered, which is not preferable. 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.

  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).

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

<Refractive index adjustment layer>
Next, the refractive index adjustment layer 13 will be described in detail. The refractive index adjustment layer 13 reduces the refractive index difference at the interface existing between the light transmissive substrate 12 and the functional layer 15 by satisfying one or more of the above-described conditions (a) to (i). It is intended to suppress the reflection at the interface and make the interference fringes inconspicuous. The refractive index adjusting layer 13 is not particularly limited as long as it has in-plane birefringence and visible light permeability. The refractive index adjusting layer 13 may have a function other than adjusting the refractive index between the light-transmitting substrate 12 and the functional layer 15. For example, the primer layer may form the refractive index adjustment layer 13 by giving an in-plane refractive index difference to the primer layer, more specifically, a primer layer that functions as an easy adhesion layer. .

  The refractive index adjusting layer 13 having in-plane birefringence formed on the light-transmitting substrate 12 is formed by a layer formed by aligning molecules (for example, liquid crystal molecules) or compounds having refractive index anisotropy. obtain. Such a refractive index adjustment layer 13 is obtained by applying a composition containing a refractive index anisotropic molecule or a refractive index anisotropic compound on the light-transmitting substrate 12 and curing the composition. As an example, when the light-transmitting substrate 12 is made of a stretched film or the like and has a regular molecular orientation, the liquid crystal molecules applied on the light-transmitting substrate 12 are Due to the nature, the light transmissive substrate 12 can be oriented with regularity corresponding to the molecular orientation. Thereby, the obtained refractive index adjusting layer 13 comes to have in-plane birefringence corresponding to the birefringence of the light-transmitting substrate 12, and the above-described condition (a) is determined by the refractive index adjusting layer 13. ~ (I) may be satisfied. In addition, from the viewpoint of further stabilizing the orientation of the refractive index anisotropic molecule or refractive index anisotropic compound contained in the refractive index adjustment layer 13, it is not dependent only on the orientation of the light-transmitting substrate 12, The refractive index anisotropic molecules and the refractive index anisotropic compounds contained in the refractive index adjusting layer 13 may be positively aligned by rubbing alignment or optical alignment.

  As another method, the refractive index adjusting layer 13 having in-plane birefringence can be obtained by stretching the resin layer. Generally, by stretching a layer made of a resin after adjusting conditions such as temperature, the layer made of the resin exhibits in-plane birefringence. Therefore, the refractive index adjustment layer 13 is produced on the light transmissive substrate 12 before stretching, and the light transmissive substrate 12 and the refractive index adjustment layer 13 are stretched simultaneously, thereby birefringence in the light transmissive substrate 12. The birefringence corresponding to the birefringence of the light transmissive substrate 12 can be imparted to the refractive index adjusting layer 13 as well.

  More specifically, first, the composition that forms the refractive index adjusting layer 13 is applied onto the light-transmitting substrate 12 before stretching, and the composition is applied on the light-transmitting substrate 12. The refractive index adjusting layer 13 is obtained by curing. As a material for forming the refractive index adjusting layer 13, a resin material exhibiting birefringence by stretching can be widely used, and it is preferable that the affinity for the light-transmitting substrate 12 is high. Thermoplastic or thermosetting polyester resins, urethane resins, acrylic resins, modified products thereof, and the like are exemplified as the resin material forming the refractive index adjustment layer 13. The light-transmitting substrate 12 to which the composition that forms the refractive index adjusting layer 13 is applied can use the various resin films described above, but is stretched at a low magnification in the machine direction during extrusion molding. A resin film is preferred. Since the flatness of the light transmissive substrate 12 is ensured by stretching in the machine direction (extrusion direction during extrusion molding of the light transmissive substrate 12), the refractive index formed on the light transmissive substrate 12 The adjustment layer 13 can be made uniform.

  Thereafter, the laminated substrate 11 including the light transmissive substrate 12 and the refractive index adjusting layer 13 formed on the light transmissive substrate 12 is heated to a temperature equal to or higher than the glass transition temperature. Stretch in the direction. As described above, when the stretching ratio in the transverse direction is very large compared to the stretching ratio in the longitudinal direction, the stretching axis of the light-transmitting substrate 12 is generally oriented in the lateral direction. The slow axis of the light-transmitting substrate 12 made of a polyester terephthalate film extends substantially in the lateral direction. On the other hand, the refractive index adjusting layer 13 is stretched only in the lateral direction. Therefore, anisotropy corresponding to the birefringence of the light-transmitting substrate 12 even if the refractive index adjustment layer 13 is formed from a resin material that is less likely to be birefringent than the light-transmitting substrate 12. A certain degree of birefringence is provided.

  According to the above method, birefringence is imparted not only to the light transmissive substrate 12 but also to the refractive index adjustment layer 13 by the stretching process for imparting birefringence to the light transmissive substrate 12. Can do. In addition, since the light-transmitting substrate 12 and the refractive index adjustment layer 13 are stretched in a heated state, the advantage that the adhesion between the light-transmitting substrate 12 and the refractive index adjustment layer 13 is improved can be enjoyed. can do.

Each refractive index _{n 2,} n _2x refractive index adjusting layer 13, _{n 2y,} n _2a, the _{n 2b} (see FIGS. 3 and 4), as already described, the refractive index of the light transmissive substrate 12 n ₁ , n _1x , n _1y and the refractive indexes n ₃ , n _3x , and n _{3y of the} functional layer 15 can be set as appropriate. As an example, when the light transmissive substrate 12 is made of a polyethylene terephthalate film and the functional layer 15 functions as a hard coat layer, the refractive index n ₂ of the refractive index adjusting layer 13 is 1.50 to 1.70. The refractive index n _2x of the refractive index adjustment layer 13 can be 1.55 to 1.75, and the refractive index n _2y of the refractive index adjustment layer 13 is 1.45 to 1.65. The refractive index n _2a of the refractive index adjustment layer 13 can be 1.51 to 1.69, and the refractive index n _2b of the refractive index adjustment layer 13 is 1.46 to 1. .64.

The thickness of the refractive index adjustment layer 13 can be 30 nm or more and 10 μm or less. When the thickness of the refractive index adjustment layer 13 is less than 30 nm, the uniformity of the refractive index adjustment layer 13 is lowered.
The upper limit of the thickness of the refractive index adjustment layer 13 is not particularly set in terms of the function of the refractive index adjustment layer 13, but is preferably set to 1 μm or less for industrial reasons.

  In addition, the thickness (at the time of hardening) of the refractive index adjustment layer 13 is measured values of arbitrary 10 points obtained by observing the cross section of the refractive index adjustment layer 13 with an electron microscope (SEM, TEM, STEM), for example. As an average value (nm). When the thickness of the refractive index adjustment 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 the center part which divided the thick line width into 2 equally as a boundary line.

<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 laminate 10 shown in FIG. 1, the functional layer 15 is composed of a hard coat layer formed on one surface of the laminate substrate 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 one surface of the laminated base material 11, the 2nd functional layer 17 is a hard-coat layer. It is comprised from the low-refractive-index layer formed on the surface on the opposite side to the laminated base material 11 of. 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 formed by applying a composition for forming a hard coat layer containing an ionizing radiation curable resin, which is a resin curable by ultraviolet rays or an electron beam, and a photopolymerization initiator onto the laminated base material 11. It can be produced by curing the composition for forming a hard coat layer on the substrate 11. The hard coat layer obtained by this method is optically isotropic and does not have in-plane birefringence. Therefore, the refractive indexes n ₃ , n _3x , and n _3y of the functional layer 15 made of this hard coat layer have the same value. Specifically, the refractive indexes n ₃ , n _3x , and n _3y of the functional layer 15 made of a hard coat layer can be set to 1.45 to 1.65, respectively. 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 ionizing radiation curable resin of the hard coat layer forming composition include compounds having one or more unsaturated bonds such as compounds having an acrylate functional group. Examples of the compound having one unsaturated bond include ethyl (meth) acrylate, ethylhexyl (meth) acrylate, styrene, methylstyrene, N-vinylpyrrolidone and the like. Examples of the compound having two or more unsaturated bonds include polymethylolpropane tri (meth) acrylate, hexanediol (meth) acrylate, tripropylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, pentaerythritol tri ( Polyfunctional compounds such as (meth) acrylate, dipentaerythritol hexa (meth) acrylate, 1,6-hexanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, or the above polyfunctional compound and (meth) acrylate And the like (eg, poly (meth) acrylate esters of polyhydric alcohols). In the present specification, “(meth) acrylate” refers to methacrylate and acrylate.

  In addition to the above compounds, relatively low molecular weight polyester resins having unsaturated double bonds, polyether resins, acrylic resins, epoxy resins, urethane resins, alkyd resins, spiroacetal resins, polybutadiene resins, polythiol polyene resins, etc. It can be used as an ionizing radiation curable resin.

  The ionizing radiation curable resin is used in combination with a solvent-drying resin (a thermoplastic resin or the like, which is a resin that forms a film only by drying the solvent added to adjust the solid content during coating). You can also By using a solvent-drying resin in combination, coating defects on the coated surface can be effectively prevented. The solvent-drying resin that can be used in combination with the ionizing radiation curable resin is not particularly limited, and a thermoplastic resin can be generally used. The thermoplastic resin is not particularly limited. For example, a styrene resin, a (meth) acrylic resin, a vinyl acetate resin, a vinyl ether resin, a halogen-containing resin, an alicyclic olefin resin, a polycarbonate resin, or a polyester resin. Examples thereof include resins, polyamide-based resins, cellulose derivatives, silicone-based resins, rubbers, and elastomers. The thermoplastic resin is preferably amorphous and soluble in an organic solvent (particularly a common solvent capable of dissolving a plurality of polymers and curable compounds). In particular, from the viewpoints of film forming properties, transparency, and weather resistance, styrene resins, (meth) acrylic resins, alicyclic olefin resins, polyester resins, cellulose derivatives (cellulose esters, etc.) and the like are preferable.

  Moreover, the said composition for hard-coat layer formation may contain the thermosetting resin. The thermosetting resin 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 Examples thereof include resins, silicon resins, polysiloxane resins, and the like.

  The photopolymerization initiator is not particularly limited, and known ones can be used. For example, specific examples of the photopolymerization initiator include acetophenones, benzophenones, Michler benzoylbenzoate, α-amylo. Examples include oxime esters, thioxanthones, propiophenones, benzyls, benzoins, and acylphosphine oxides. In addition, it is preferable to use a mixture of photosensitizers, and specific examples thereof include n-butylamine, triethylamine, poly-n-butylphosphine, and the like.

  As the photopolymerization initiator, when the ionizing radiation curable resin is a resin system having a radical polymerizable unsaturated group, acetophenones, benzophenones, thioxanthones, benzoin, benzoin methyl ether, etc. may be used alone or in combination. It is preferable to use it. When the ionizing radiation curable resin is a resin system having a cationic polymerizable functional group, the photopolymerization initiator may be an aromatic diazonium salt, aromatic sulfonium salt, aromatic iodonium salt, metallocene compound, benzoin sulfone. It is preferable to use acid esters alone or as a mixture.

  The content of the photopolymerization initiator in the hard coat layer forming composition is preferably 1 to 10 parts by mass with respect to 100 parts by mass of the ionizing radiation curable resin. When the amount is less than 1 part by mass, the hardness of the hard coat layer in the laminate 10 may not be sufficiently hard. When the amount exceeds 10 parts by mass, ionizing radiation does not reach the deep part of the coated film. This is because curing may not be promoted. The minimum with more preferable content of the said photoinitiator is 2 mass parts, and a more preferable upper limit is 8 mass parts. When the content of the photopolymerization initiator is in this range, a hardness distribution does not occur in the film thickness direction, and uniform hardness is likely to occur.

  The composition for forming a hard coat layer may contain a solvent. As said solvent, it can select and use according to the kind and solubility of the resin component to be used, for example, ketones (acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, diacetone alcohol etc.), ethers ( Dioxane, tetrahydrofuran, propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, etc.), aliphatic hydrocarbons (hexane, etc.), alicyclic hydrocarbons (cyclohexane, etc.), aromatic hydrocarbons (toluene, xylene, etc.), Halogenated carbons (dichloromethane, dichloroethane, etc.), esters (methyl acetate, ethyl acetate, butyl acetate, etc.), water, alcohols (ethanol, isopropanol, butanol, cyclohexanol, etc.), cellosolves (methyl cello) Lube, ethyl cellosolve), cellosolve acetates, sulfoxides (dimethyl sulfoxide), amides (dimethylformamide, dimethylacetamide, etc.) and the like can be exemplified, it may be a mixed solvent thereof.

  Although it does not specifically limit as a content rate (solid content) of the raw material in the said composition for hard-coat layer formation, Usually, it is preferable to set it as 5-70 mass%, especially 25-60 mass%.

  According to the purpose of increasing the hardness of the hard coat layer, suppressing curing shrinkage, controlling the refractive index, imparting antiglare properties, etc., the hard coat layer forming composition, Surfactant, antistatic agent, silane coupling agent, thickener, anti-coloring agent, coloring agent (pigment, dye), antifoaming agent, leveling agent, flame retardant, ultraviolet absorber, adhesion promoter, polymerization inhibitor In addition, an antioxidant, a surface modifier, a lubricant and the like may be added.

  Moreover, the said composition for hard-coat layer formation may mix and use a photosensitizer, As a specific example, n-butylamine, a triethylamine, poly-n-butylphosphine etc. are mentioned, for example. .

  The method for preparing the composition for forming a hard coat layer is not particularly limited as long as each component can be uniformly mixed. For example, the composition can be performed using a known apparatus such as a paint shaker, a bead mill, a kneader, or a mixer.

  Moreover, it does not specifically limit as a method of apply | coating the said composition for hard-coat layer formation on the laminated base material 11, For example, a spin coat method, a dip method, a spray method, a die coat method, a bar coat method, a roll coater method, Well-known methods such as meniscus coater method, flexographic printing method, screen printing method and peade coater method can be mentioned.

  The coating film formed by applying the hard coat layer forming composition on the laminated substrate 11 is preferably heated and / or dried as necessary and cured by irradiation with active energy rays or the like.

  Examples of the active energy ray irradiation include irradiation with ultraviolet rays or electron beams. Specific examples of the ultraviolet light source include light sources such as an ultrahigh pressure mercury lamp, a high pressure mercury lamp, a low pressure mercury lamp, a carbon arc lamp, a black light fluorescent lamp, and a metal halide lamp. Moreover, as a wavelength of an ultraviolet-ray, the wavelength range of 190-380 nm can be used. Specific examples of the electron beam source include various electron beam accelerators such as a cockcroft-wald type, a bandegraft type, a resonant transformer type, an insulated core transformer type, a linear type, a dynamitron type, and a high frequency type.

  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 forming composition described above 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 forming 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.

  Further, the antiglare layer can be formed, for example, by adding an antiglare agent to the hard coat layer forming 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 layer formation 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 laminated substrate and laminate>
According to the laminated base material 11 and the laminated body 10 that have been described above as one embodiment, between the functional layer 15 provided on the laminated base material 11 and the light transmissive base material 12 of the laminated base material 11. In addition, a refractive index adjustment layer 13 is provided. The refractive index of the refractive index adjusting layer 13 has in-plane birefringence, and similarly, in the slow axis direction dx and the fast axis direction dy of the light-transmitting substrate 12 having in-plane birefringence. The refractive index along both directions is adjusted between the light-transmitting substrate 12 and the functional layer 15. More specifically, there is no optical interface in which the refractive index in the slow axis direction dx of the light transmissive substrate 12 changes greatly between the light transmissive substrate 12 and the functional layer 15, and the light There is no optical interface in which the refractive index of the transmissive substrate 12 changes greatly in the fast axis direction dy. That is, there is no interface between the light-transmitting substrate 12 and the functional layer 15 that causes a high reflectivity due to a large difference in refractive index. Therefore, it is possible to effectively prevent light that has entered the laminated body 10 from the functional layer 15 side and is reflected before reaching the light-transmitting substrate 12 having in-plane birefringence. Can do. Thereby, the interference fringes that can be visually recognized due to the interference between the light reflected on the surface of the laminated body 10 and the light reflected on the inside of the laminated body 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 base material 11 and the laminated body 10 described here, it is possible to effectively make both azimuth and interference fringes inconspicuous.

  Furthermore, if the refractive index adjusting 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. . However, the thickness is not limited to this example, and the thickness is less than 30 nm between at least one of the light-transmitting substrate 12 and the refractive index adjusting layer 13 and between the refractive index adjusting layer 13 and the functional layer 15. The primer layer may be provided separately from the refractive index adjustment layer 13. Even when a primer layer having a thickness of less than 30 nm is provided, the above-described effect of making the interference fringes inconspicuous by the refractive index adjustment layer 13 is effectively exhibited, and further, for example, an easy adhesion effect due to the primer layer is expected. can do.

≪Polarizing plate≫
The laminated base material 11 and the laminated body 10 can be used by being incorporated into the polarizing plate 20, for example. FIG. 5 is a schematic configuration diagram of the polarizing plate 20 in which the laminate 10 and the laminate substrate 11 shown in FIG. 1 are incorporated. 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 base material 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 laminated base material 11, the laminated body 10, and the polarizing plate 20 can be used by being incorporated in a liquid crystal display panel. FIG. 6 is a schematic configuration diagram of the liquid crystal display panel 30 incorporating the laminate 10 and the laminate substrate 11 shown in FIG. 1 and the polarizing plate 20 shown in FIG.

  The liquid crystal display panel shown in FIG. 6 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 laminated base material 11, the laminated body 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. 7 shows an example of an image display device 40 incorporating the laminate 10 and laminate substrate 11 shown in FIG. 1, the polarizing plate 20 shown in FIG. 5, and the liquid crystal display panel 30 shown in FIG. It is a schematic block diagram of the liquid crystal display which is.

  The image display device 40 shown in FIG. 7 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.

≪Other uses≫
In addition, the laminated base material 11 and the laminated body 10 described above may be provided on the image display device 30 via a touch panel sensor as an application other than an application directly arranged on the display surface of the image display device 30. Good. In this example, a touch panel device in which the laminated base material 11 or the laminated body 10 is arranged on the touch panel sensor directly or via other members is prepared in advance, and the touch panel device is provided on the image display device. It may be.

  Furthermore, the laminated base material 11 and the laminated body 10 described above can be used in various applications where generation of interference fringes should be avoided. For example, the laminated base material 11 and the laminated body 10 can also 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.

  As described below, laminates according to Examples 1 and 2 and Comparative Example 1 were produced. About each produced laminated body, generation | occurrence | production of the interference fringe and generation | occurrence | production of nidimura were investigated.

Example 1
The polyethylene terephthalate material was melted at 290 ° C., extruded through a film-forming die, into a sheet form, closely adhered onto a water-cooled and cooled rotating quenching drum, and cooled to produce an unstretched film. This unstretched film was preheated at 120 ° C. for 1 minute with a biaxial stretching test apparatus (manufactured by Toyo Seiki Co., Ltd.), and then stretched at 120 ° C. at a stretch ratio of 4.5 times. Stretching was performed at a stretching ratio of 1.5 times in the direction of the degree to obtain a light-transmitting substrate having n _1x = 1.70, n _1y = 1.60, a film thickness of 80 μm, and a retardation = 8000 nm.

A photopolymerizable liquid crystal compound is dissolved in a mixed solvent of cyclohexanone and n-propyl alcohol (solvent ratio 9: 1) on a light-transmitting base material in an amount of 20% by mass, and a photopolymerization initiator Irg184 (Ciba Specialty Chemicals Co., Ltd.) )) Was added with a bar coater so that the film thickness after drying was 0.5 μm. Subsequently, the solvent is removed by heating at 70 ° C. for 4 minutes, the photopolymerizable liquid crystal compound is aligned, and the coated surface is irradiated with ultraviolet rays to fix the photopolymerizable liquid crystal compound, A refractive index adjusting layer of n _2x = 1.60 and n _2y = 1.55 was laminated.

Next, as a functional layer, optically isotropic pentaerythritol triacrylate (PETA) is dissolved in 30% by mass in MIBK solvent, and a photopolymerization initiator Irg184 (Ciba Specialty Chemicals Co., Ltd.) is added. The ink added at 5% with respect to the solid content was applied by a bar coater so that the film thickness after drying was 5 μm. Next, heating is performed at 70 ° C. for 2 minutes to remove the solvent, and the coated surface is irradiated with ultraviolet rays to be fixed, and a functional layer of n _3x = n _3y = 1.50 is laminated. A laminate was obtained.

(Example 2)
The polyethylene terephthalate material was melted at 290 ° C., extruded through a film-forming die, into a sheet form, closely adhered onto a water-cooled and cooled rotating quenching drum, and cooled to produce an unstretched film. This unstretched film was preheated at 120 ° C. for 1 minute with a biaxial stretching test apparatus (manufactured by Toyo Seiki Co., Ltd.), and then stretched at 120 ° C. at a stretch ratio of 4.5 times. The film was stretched at a stretching ratio of 1.5 times in the direction of degree to obtain a light-transmitting substrate having n _1x = 1.70, n _1y = 1.60, a film thickness of 33 μm, and a retardation = 3300 nm. On the obtained light-transmitting substrate, a refractive index adjusting layer and a functional layer were formed in the same manner as in Example 1 to obtain a laminate according to Example 2. That is, the laminate according to Example 2 is different from the laminate according to Example 1 in the thickness of the light-transmitting substrate.

(Comparative Example 1)
In the same manner as the laminate according to Example 1, except that an intermediate layer made of pentaerythritol triacrylate: antimony pentoxide = 7: 3 was used instead of the refractive index adjustment layer of Example 1, a comparative example 1 was produced. The intermediate layer of the laminate according to Comparative Example 1 was optically isotropic, and n _2x = n _2y = 1.575.

(Reference Example 1)
The polyethylene terephthalate material was melted at 290 ° C., extruded through a film-forming die, into a sheet form, closely adhered onto a water-cooled and cooled rotating quenching drum, and cooled to produce an unstretched film. This unstretched film was preheated at 120 ° C. for 1 minute with a biaxial stretching test apparatus (manufactured by Toyo Seiki Co., Ltd.), and then stretched at 120 ° C. at a stretch ratio of 4.5 times. Stretching was performed at a stretching ratio of 1.5 times in the direction of the degree to obtain a light-transmitting substrate having n _1x = 1.70, n _1y = 1.60, film thickness 28 μm, and retardation = 2800 nm. On the obtained light-transmitting substrate, a refractive index adjusting layer and a functional layer were formed in the same manner as in Example 1 to obtain a laminate according to Reference Example 1. That is, the laminate according to Example 2 is different from the laminate according to Example 1 in the thickness of the light-transmitting substrate.

(Measurement of refractive index and retardation of light-transmitting substrate)
The refractive index and retardation of the light-transmitting substrate were measured as follows. First, the stretched light-transmitting substrate is obtained by using two polarizing plates to determine the orientation axis direction of the film, and the refractive index (nx, ny) with respect to a wavelength of 590 nm of two axes orthogonal to the orientation axis direction. Was determined by an Abbe refractometer (NAR-4T manufactured by Atago Co., Ltd.). Here, an axis showing a larger refractive index is defined as a slow axis. The film thickness d (nm) was measured using an electric micrometer (manufactured by Anritsu), and the unit was converted to nm. The retardation was calculated from the product of the refractive index difference (n _1x −n _1y ) and the film thickness d (nm).

(Measurement of refractive index of refractive index adjustment layer)
The refractive index of the refractive index adjusting layer was measured as follows. In the case of the photopolymerizable liquid crystal compounds used in Examples 1 and 2, polyimide, which is an alignment film material, is applied to a glass substrate that is optically isotropic and subjected to rubbing treatment. An ink obtained by dissolving 20% by mass of a photopolymerizable liquid crystal compound on this base material in a mixed solvent of cyclohexanone and n-propyl alcohol (solvent ratio 9: 1) was dried to a film thickness of 1 μm using a spin coater. It applied so that it might become. Subsequently, the solvent is removed by heating at 70 ° C. for 4 minutes, the photopolymerizable liquid crystal compound is aligned, and the coated surface is irradiated with ultraviolet rays to fix the photopolymerizable liquid crystal compound. The refractive index of the refractive index adjusting layer was measured by the same method as that for the light-transmitting substrate.

(Determination of whether or not it has birefringence)
Whether or not it has birefringence was determined as follows. Using a KOBRA-WR manufactured by Oji Scientific Instruments, the measurement angle is set to 0 ° and the measurement wavelength is 589.3 nm, the in-plane phase difference is measured, and the in-plane phase difference of less than 20 nm has birefringence. It was judged that there was no birefringence, and those with a thickness of 20 nm or more were judged.

(Refractive index measurement of isotropic material)
The refractive index of the isotropic material (intermediate layer and functional layer) was measured with an Abbe refractometer (NAR-4T manufactured by Atago Co., Ltd.).

(Interference fringe evaluation)
Generation | occurrence | production of the interference fringe in each laminated body was evaluated as follows. Using an interference fringe inspection lamp (Na lamp) manufactured by Funatec Co., Ltd., the presence or absence of interference fringes in the antiglare film obtained by visual inspection was examined and evaluated according to the following criteria. The obtained antiglare film was evaluated by reflection observation by painting the opposite side of the coated surface with black ink and applying an interference fringe inspection lamp to the coated surface.
○: Interference fringes are observed, but they are extremely thin, and there is no problem in practical use.
X: Interference fringes are clearly observed.

(Nijimura evaluation)
The occurrence of Nijimura in each sample was evaluated as follows. Each laminated base material was arrange | positioned on the polarizing element by the side of the observer of LED backlight liquid crystal monitor (FLATRON IPS226V (made by LG Electronics Japan)), and the liquid crystal display device was produced. In addition, it arrange | positioned so that the angle which the slow axis of a polyester base material and the absorption axis of the polarizing element by the side of the observer of a liquid crystal monitor may make would be 45 degrees. In the dark and bright places (illuminance around the LCD monitor 400 lux), the display image is observed visually and through polarized sunglasses from the front and oblique directions (about 50 degrees), and the presence or absence of nidimra is evaluated according to the following criteria. did. Observation through polarized sunglasses is a much stricter evaluation method than visual observation. The observation is performed by 10 people, and the largest number of evaluations are the observation results.
◎: Nizimura is not observed ○: Nizimura is observed, but there is no problem in practical use ×: Nizimura is observed strongly

The evaluation results of interference fringes and Nizimura are shown in Table 1.

Claims (16)

A laminated base material in which a functional layer is formed on one surface to form a laminated body,
A light-transmitting substrate having in-plane birefringence;
A refractive index adjusting layer laminated with the light transmissive substrate and having in-plane birefringence, wherein the refractive index adjusting layer is positioned between the light transmissive substrate and the functional layer; With
The refractive index n _1x in the slow axis direction that is the direction in which the refractive index is the largest in the plane of the light transmissive substrate, and the refractive index adjustment layer in the direction parallel to the slow axis direction of the light transmissive substrate. refractive index n _2x, and the refractive index n _3x of the functional layer in the direction parallel with the slow axis direction of the light transmitting substrate,
n _1x <n _2x <n _3x , or n _1x > n _2x > n _3x
Satisfy the relationship
Refractive index n _1y in the fast axis direction orthogonal to the slow axis direction of the light transmissive substrate, and refractive index of the refractive index adjusting layer in a direction parallel to the fast axis direction of the light transmissive substrate. n _2y , and the refractive index n _{3y of the} functional layer in a direction parallel to the fast axis direction of the light transmissive substrate,
n _1y <n _2y <n _3y or n _1y > n _2y > n _3y
A laminated substrate that satisfies the relationship. The refractive index n _2x of the refractive index adjusting layer in a direction parallel to the slow axis direction of the light transmissive substrate, and the refractive index in a direction parallel to the fast axis direction of the light transmissive substrate. The refractive index n _{2y of the} adjustment layer is
n _2x > n _2y
The laminated substrate according to claim 1, which satisfies the following relationship. The refractive index n _1x in the slow axis direction of the light transmissive substrate, the refractive index n _{1y in the fast} axis direction of the light transmissive substrate, and parallel to the slow axis direction of the light transmissive substrate. A refractive index n _2x of the refractive index adjusting layer in a specific direction, and a refractive index n _2y of the refractive index adjusting layer in a direction parallel to the fast axis direction of the light-transmitting substrate,
(N _1x -n _1y )> (n _2x -n _2y )
The laminated substrate according to claim 2, satisfying the following relationship.   When the laminated base material is observed from the normal direction, the refractive index adjusting layer is the slow axis direction of the light transmissive base material and the direction in which the refractive index is the largest in the plane of the refractive index adjusting layer. The laminated base material according to any one of claims 1 to 3, wherein a magnitude of an angle formed by the slow axis direction is less than 45 °.   The slow axis direction of the light-transmitting substrate is parallel to the slow axis direction of the refractive index adjustment layer, which is the direction in which the refractive index is greatest in the plane of the refractive index adjustment layer. The laminated base material as described in any one of 1-4. The refractive index n _1x in the slow axis direction of the light transmissive substrate, the refractive index n _{1y in the fast} axis direction of the light transmissive substrate, and the highest refractive index in the plane of the refractive index adjustment layer. refractive index n _2a in the slow axis direction of the refractive index adjusting layer which is a _direction, and a refractive index n _2b in fast axis direction of the refractive index adjusting layer which is orthogonal to the slow axis direction of the refractive index adjusting layer (N _1x −n _1y )> (n _2a −n _2b )
The laminated substrate according to claim 4 or 5, which satisfies the following relationship. The refractive index n _1x in the slow axis direction of the light transmissive substrate, the refractive index n _2x of the refractive index adjustment layer in a direction parallel to the slow axis direction dx of the light transmissive substrate, and The refractive index n _{3x of the} functional layer in a direction parallel to the slow axis direction of the light transmissive substrate is
n ₂ = (n _2x + n _2y ) / 2 and | n _2x − ((n _1x + n _3x ) / 2) | <| n ₂ − ((n _1x + n _3x ) / 2) |
Satisfy the relationship
The refractive index n _{1y in the fast} axis direction of the light transmissive substrate, the refractive index n _2y of the refractive index adjustment layer in the direction parallel to the _fast axis direction of the light transmissive substrate, and the light The refractive index n _{3y of the} functional layer in a direction parallel to the fast axis direction of the transparent substrate is
n ₂ = (n _2x + n _2y ) / 2 and | n _2y − ((n _1y + n _3y ) / 2) | <| n ₂ − ((n _1y + n _3y ) / 2) |
The laminated substrate according to any one of claims 1 to 6, which satisfies the following relationship.   The laminated substrate according to any one of claims 1 to 7, wherein the laminated substrate has a retardation of 3000 nm or more.   The laminated substrate according to any one of claims 1 to 7, wherein the light transmissive substrate has a retardation of 3000 nm or more. The laminated substrate according to any one of claims 1 to 10,
A functional layer formed on one surface of the laminated base material,
The laminated body in which the refractive index adjusting layer is located between the light transmissive substrate and the functional layer.   The laminate according to claim 10, wherein the functional layer is a hard coat layer.   The laminate according to claim 10 or 11, further comprising a second functional layer provided on the opposite side of the functional layer from the laminated base material side.   The laminate according to claim 12, wherein the second functional layer is a low refractive index layer having a lower refractive index than the functional layer. A polarizing element;
A laminated substrate according to any one of claims 1 to 9 or a laminate according to any one of claims 10 to 13.   A liquid crystal display panel provided with the laminated substrate according to any one of claims 1 to 9, the laminate according to any one of claims 10 to 13, or the polarizing plate according to claim 14.   An image display device comprising the laminate substrate according to any one of claims 1 to 9, the laminate according to any one of claims 10 to 13, or the polarizing plate according to claim 14.

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