JP6815955B2 - Laminates, polarizing plates, liquid crystal display panels and image display devices - Google Patents

Description

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

On an image display surface in 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), or a field emission display (FED), a direct or other member (for example, for example) is usually used. A laminate 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 for the purpose of improving scratch resistance is exemplified.

Further, as the light-transmitting base material of the laminate supporting the functional layer, an optically isotropic film having no birefringence, typically a film made of a cellulose ester typified by triacetyl cellulose is used. It is used. When a film having birefringence is applied to the 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 "Nijimura") is visually recognized. Because it ends up. However, the cellulose ester film has drawbacks such as inferior moisture and heat resistance and deterioration of polarizing plate functions such as polarization function and hue when used in a high temperature and high humidity environment.

From such a problem of the cellulose ester film, it is desired to use a general-purpose film that is easily available on the market or can be manufactured by a simple method as a light-transmitting base material of the laminate. Various studies have been done. 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 30,000 nm is arranged so that the angle between the absorption axis of the polarizing plate and the slow axis of the polymer film is 45 degrees. It has been reported that when the screen is observed through a polarizing plate such as sunglasses, good visibility can be ensured regardless of the observation angle.

Japanese Unexamined Patent Publication No. 2011-107198

However, when the hard coat layer is formed on the polyester or polycarbonate film which is the preferable polymer film in Patent Document 1, although it is possible to suppress the generation of Nijimura, another problem is that the interference fringes are invisible. It becomes a problem. Here, the interference fringes are partially caused by the interference between the light reflected on the surface of the functional layer and the light once incident on the functional layer and reflected at the interface between the functional layer and the light transmissive substrate. It is a phenomenon in which various iris-like colors are seen, and it is a phenomenon that occurs because the wavelengths that strengthen each other change depending on the viewing direction. This phenomenon is not only hard to see for the user but also gives an unpleasant impression, and improvement is strongly required.

As a countermeasure against interference fringes, it is conceivable to reduce the difference in refractive index between the functional layer and the light-transmitting base material and reduce the reflectance at the interface between the functional layer and the light-transmitting base material. However, when the light-transmitting base material has in-plane birefringence and its retardation value is high, in order to avoid increasing the thickness of the light-transmitting base material from the viewpoint of cost and the like, It becomes necessary to increase the difference in refractive index between the refractive index in the slow axis direction and the refractive index in the phase advance axis direction in the plane of the light transmissive substrate. Therefore, it is difficult to reduce the difference in refractive index between the functional layer and the light-transmitting substrate in both the slow-phase axial direction and the phase-advancing axial direction, and as a result, the interference fringes cannot be sufficiently noticeable. Can not.

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

The laminated base material according to the present invention
A laminated base material in which a functional layer is formed on one surface to form a laminated body.
With an in-plane birefringent light-transmitting substrate,
A refractive index adjusting layer that is laminated with the light transmitting base material and has in-plane birefringence, and is located between the light transmitting base material and the functional layer. With
The refractive index n _1x in the slow axis direction, which is the direction in which the refractive index is the largest in the plane of the light transmissive substrate, and the refractive index adjusting layer in the direction parallel to the slow axis direction of the light transmissive substrate. The refractive index n _{2x of} the functional layer and the refractive index n _{3x of the} functional layer in the direction parallel to the slow axis direction of the light transmissive substrate.
n _1x <n _2x <n _3x , or n _1x > n _2x > n _3x
Satisfy the relationship
The refractive index n _1y in the phase-advancing axis direction orthogonal to the slow-phase axis direction of the light-transmitting base material, and the refractive index of the refractive index adjusting layer in the direction parallel to the phase-advancing axis direction of the light-transmitting base material. n _2y and the refractive index n _{3y of the} functional layer in the direction parallel to the phase advance axis direction of the light transmissive substrate are
n _1y <n _2y <n _3y or n _1y > n _2y > n _3y
Satisfy the relationship.

In the laminated base material according to the present invention, the refractive index n _2x of the refractive index adjusting layer in the direction parallel to the slow axis direction of the light transmissive base material and the phase advance axial direction of the light transmissive base material. The refractive index n _2y of the refractive index adjusting layer in the direction parallel to
n _2x > n _2y
The relationship may be satisfied.

In the laminated base material according to the present invention, the refractive index n _{1x of} the light transmissive base material in the slow axis direction, the refractive index n _{1 y of} the light transmissive base material in the phase advance axial direction, and the light transmissive base material. The refractive index n _2x of the refractive index adjusting layer in the direction parallel to the slow axis direction and the refractive index n of the refractive index adjusting layer in the direction parallel to the phase advance axis direction of the light transmissive substrate. _2y is (n _1x −n _1y )> (n _2x −n _2y )
The relationship may be satisfied.

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 magnitude of the angle formed by the slow axis direction of the refractive index adjusting layer, which is the direction, may be less than 45 °.

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

In the laminated base material according to the present invention, the refractive index n _{1x of} the light transmissive base material in the slow axis direction, the refractive index n _{1 y of} the light transmissive base material in the phase advance axis direction, and the refractive index adjusting layer. The refractive index n _2a in the slow axis direction of the refractive index adjusting layer, which is the direction having the largest refractive index in the plane, and the advance of the refractive index adjusting layer orthogonal to the slow axis direction of the refractive index adjusting layer. The refractive index n _2b in the phase axis direction is
(N _1x −n _1y )> (n _2a −n _2b )
The relationship may be satisfied.

In the laminated substrate according to the present invention
The refractive index n _{1x of} the light transmitting substrate in the slow axis direction, the refractive index n _2x of the refractive index adjusting layer in the direction parallel to the slow axis direction dx of the light transmitting substrate, and The refractive index n _{3x of the} functional layer in the 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 of} the light-transmitting substrate in the phase-advancing axis direction, the refractive index n _2y of the refractive index adjusting layer in the direction parallel to the phase-advancing axis direction of the light-transmitting substrate, and the light. The refractive index _{n3y of the} functional layer in the direction parallel to the phase-advancing axis direction of the permeable base material is
n ₂ = (n _2x + n _2y ) / 2 and | n _2y − ((n _1y + n _3y ) / 2) | <| n ₂ − ((n _1y + n _3y ) / 2) |
The relationship may be satisfied.

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

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

The laminate according to the present invention
With any of the laminated substrates according to the present invention described above,
A functional layer formed on one surface of the laminated base material is provided.
The refractive index adjusting layer is located between the light-transmitting base material and the functional layer.

In the laminated body 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 side of the functional layer opposite to 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
Polarizing element and
The laminate includes any of the above-mentioned laminated base materials according to the present invention, any of the above-mentioned laminates according to the present invention, and the laminate according to any one of claims 9 to 12.

The polarizing plate according to the present invention includes either the above-mentioned laminated base material according to the present invention, the above-mentioned laminate according to the present invention, or the above-mentioned polarizing plate according to the present invention.

The image display device according to the present invention includes either the above-mentioned laminated base material according to the present invention, the above-mentioned laminate according to the present invention, or the above-mentioned polarizing plate according to the present invention.

The touch panel device according to the present invention is either a touch panel sensor and any of the above-mentioned laminated base materials according to the present invention provided on the touch panel sensor, any of the above-mentioned laminates according to the present invention, or the above-mentioned polarizing plate according to the present invention. It has one of.

According to the present invention, a refractive index adjusting layer having in-plane birefringence is provided between the functional layer and the light-transmitting base material having in-plane birefringence. With this refractive index adjusting layer, the reflectance of light once incident on the functional layer can be reduced. As a result, the 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 laminated body. FIG. 2 is a diagram corresponding to FIG. 1 and is a diagram showing a layer structure of another example of the functional layer. FIG. 3 is a diagram for explaining the distribution of the refractive index in the laminated body shown in FIG. 1, and is a perspective view schematically showing the laminated body. FIG. 4 is a view for explaining the in-plane birefringence of 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 showing a schematic configuration of a liquid crystal display panel including the laminate shown in FIG. FIG. 7 is a diagram showing a schematic configuration of a display device including the laminate 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, the scale, aspect ratio, etc. are appropriately changed from those of the actual product and exaggerated for the convenience of illustration and comprehension. 1 to 7 are diagrams for explaining an embodiment of the present invention. Of these, FIGS. 1 and 2 are diagrams for explaining a laminated base material and a laminated body. 3 and 4 are diagrams for explaining the distribution of the refractive index of the laminated base material and the laminated body. 5 to 7 are schematic views showing the configurations of a polarizing plate, a liquid crystal display panel, and a laminated body.

≪Laminated base material and laminate≫
<Overall composition of laminated base material 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 has a laminated base material 11 and a functional layer 15 formed on one surface of the laminated base material 11. The laminated base material 11 has a light transmitting base material 12 and a refractive index adjusting layer 13 laminated with the light transmitting base material 12. In the laminated body 10, the refractive index adjusting layer 13 is located between the light transmitting base material 12 and the functional layer 15. That is, the functional layer 15 is laminated on the laminated base material 11 from the side of the refractive index adjusting layer 13. In the illustrated example, the refractive index adjusting layer 13 is formed on one surface of the light transmissive base material 12 in the laminated base material 11. That is, the laminate 10 is configured to include three layers of a light transmitting base material 12, a refractive index adjusting layer 13, and a functional layer 15 in this order, and the refractive index adjusting layer 13 is a light transmitting group. It is arranged adjacent to the material 12 and the functional layer 15 and forms an interface between the light transmitting base material 12 and the functional layer 15, respectively.

Note that FIG. 2 shows a laminated body as a modification of the laminated body 10 shown in FIG. The laminate 10 shown in FIG. 2 is different from the laminate 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 base material 11, and the second functional layer 17 is a hard coat layer. It may be composed of a low refractive index layer formed on a surface opposite to that of the laminated base material 11.

The light-transmitting base material 12 contained in the laminated base material 11 is optically anisotropic and has at least in-plane birefringence. Further, the refractive index adjusting layer 13 contained 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 indexes of the sheet-shaped light-transmitting base material 12 in the two orthogonal directions along the sheet surface are different. Similarly, the refractive index of the sheet-shaped refractive index adjusting layer 13 in two orthogonal directions along the sheet surface is different.

Here, the "sheet surface (film surface, plate surface)" refers to the target sheet-like member when the target sheet-like (film-like, plate-like) member is viewed as a whole and from a broad perspective. Refers to the surface that coincides with the plane direction. In the example described as one embodiment, the sheet surface of the light transmissive base material 12, the sheet surface of the refractive index adjusting layer 13, the sheet surface of the functional layer 15, the sheet surface of the laminated base material 11, and the laminated body 10. The seat surfaces are parallel to each other.

Whether or not the light-transmitting base material 12 and the refractive index adjusting layer 13 have in-plane birefringence depends on whether or not the light-transmitting base material 12 or the refractive index adjusting layer 13 has in-plane birefringence at a wavelength of 550 nm. The maximum in-plane refractive index difference Δn (maximum value of the difference in refractive index in two directions along the sheet surface) is
Δn ≧ 0.0005
Judgment is made based on whether or not the above conditions are met. That is, if the maximum in-plane refractive index difference Δn of the light-transmitting base material 12 is 0.0005 or more, the light-transmitting base material 12 has birefringence, and the light-transmitting base material 12 has birefringence. If the maximum refractive index difference Δn in the plane is less than 0.0005, it is determined that the light transmissive base material 12 does not have birefringence. Similarly, if the maximum refractive index difference Δn in the plane of the refractive index adjusting layer 13 is 0.0005 or more, the refractive index adjusting layer 13 has birefringence, and the surface of the refractive index adjusting layer 13 If the maximum refractive index difference Δn is less than 0.0005, it is determined that the refractive index adjusting layer 13 does not have birefringence. The birefringence can be measured by using a KOBRA-WR manufactured by Oji Measuring Instruments Co., Ltd. by setting the measurement angle to 0 ° and the measurement wavelength to 552.1 nm. At this time, the film thickness and the average refractive index are required to calculate the birefringence. The film thickness can be measured using, for example, a micrometer (Digimatic Micrometer, manufactured by Mitutoyo Co., Ltd.) or an electric micrometer (manufactured by Anritsu Co., Ltd.) for a light-transmitting film.
When the refractive index adjusting 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 or more, and the average value is obtained as the film thickness. The average refractive index can be measured using an Abbe refractive index meter (NAR-4T manufactured by Atago Co., Ltd.) or an "ellipsometer" manufactured by JASCO Corporation.

Maximum in-plane refractive index difference Δn of TD80UL-M (manufactured by Fuji Film Co., Ltd.) made of triacetyl cellulose and ZF16-100 (manufactured by Nippon Zeon Co., Ltd.) made of cycloolefin polymer, which are generally known as isotropic materials. Is 0.0000375 and 0.00005, respectively, and is determined not to have birefringence (isotropic) by the above measurement method.

In the laminate 10 described here, the refractive index n _1x in the slow-phase axial direction dx, which is the direction in which the light-transmitting base material 12 has the largest refractive index in the plane, and the slow-phase axial direction dx of the light-transmitting base material 12. The refractive index n _2x of the refractive index adjusting layer in the direction parallel to and the refractive index n _3x of the functional layer 15 in the direction parallel to the slow-phase axial direction dx of the light-transmitting substrate 12.
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 phase-advancing axial direction dy orthogonal to the slow-phase axial direction dx in the plane of the light-transmitting base material 12 and the refraction in the direction parallel to the phase-advancing axial direction dy of the light-transmitting base material 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 phase advance axis direction dy of the light transmissive base material 12 are
n _1y <n _2y <n _3y or n _1y > n _2y > n _3y
Condition (b) is satisfied.

That is, the refractive index adjusting layer 13 is arranged between the functional layer 15 and the light-transmitting base material 12 having compound flexibility, and the slow-phase axial direction dx and the phase-advancing axial direction dy of the light-transmitting base material 12 The refractive index is changed in two steps in both directions. As a result, there is no interface between the functional layer 15 and the light-transmitting base material 12 having biflexibility, in which the refractive index of the light-transmitting base material 12 changes significantly in the slow-phase axial direction dx. In addition, there is no interface in which the refractive index of the light transmissive base material 12 changes significantly in the phase-advancing axis direction dy. That is, the difference in refractive index between the functional layer 15 and the light-transmitting base material 12 having the biflexibility in both the slow-phase axial direction dx and the phase-advancing axial direction dy of the light-transmitting base material 12 is small. Because of this, there is only an interface with low reflectance.

Therefore, it is possible to effectively prevent the light incident on the laminated body 10 from the side of the functional layer 15 from turning back in the traveling direction due to reflection while traveling toward the light transmitting base material 12. As a result, among the light incident on the laminated body 10 from the side of the functional layer 15, 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 The light reflected at the interface with the transmissive substrate 12 and the interference fringes that can be generated by the light 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 base material 12 and the refraction in the direction parallel to the phase advance axis direction dy of the light transmissive base material 12. The refractive index n _2y of the rate adjusting layer 13 is
n _2x > n _2y
It is preferable to satisfy the condition (c). In this case, the refractive index of the light-transmitting base material 12 in the slow-phase axial direction dx is gradually changed in two steps between the functional layer 15 and the light-transmitting base material 12 having the biflexibility. Moreover, the refractive index of the light-transmitting base material 12 in the phase-advancing axial direction dy can be changed little by little in two steps. As a result, it is possible to more effectively prevent the light incident on the laminated body 10 from the side of the functional layer 15 from turning back in the traveling direction due to reflection while traveling to the light transmitting base material 12. As a result, the interference fringes can be made less noticeable more effectively.

Further, when the condition (c) is satisfied, the refractive index n _{1x of} the light-transmitting base material 12 in the slow-phase axial direction dx, the refractive index n _{1y of} the light-transmitting base material 12 in the phase-advancing axial direction dy, and light transmission The refractive index n _2x of the refractive index adjusting layer 13 in the direction parallel to the slow axis direction dx of the sex substrate 12 and the refractive index adjusting layer 13 in the direction parallel to the phase advance axis direction dy of the light transmissive substrate 12. Refractive index n _2y of
(N _1x −n _1y )> (n _2x −n _2y )
It is more preferable to satisfy the condition (d). For example, the refractive index n _3x of the functional layer 15 in the direction parallel to the slow axial direction dx of the light transmissive base material 12 and the functional layer 15 in the direction parallel to the phase advance axial direction dy of the light transmissive base material 12. When the refractive indexes n _{3y of the above} are not significantly different, 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 adjusting layer 13 does not exhibit unnecessarily strong birefringence, and the refractive index is gradually increased in both the slow-phase axial direction dx and the phase-advancing axial direction dy of the light-transmitting base material 12. It can be changed in batches. As a result, it is possible to more effectively prevent the light incident on the laminated body 10 from the side of the functional layer 15 from turning back in the traveling direction due to reflection while traveling to the light transmitting base material 12. As a result, the interference fringes can be made less noticeable more effectively.

Further, as shown in FIG. 4, when the laminated base material 11 is observed from the normal direction (the normal direction of the laminated base material 11 to the sheet surface), the slow axial direction dx of the light transmissive base material 12 It is preferable that the magnitude of the angle θ formed by the slow axial direction da of the refractive index adjusting layer 13, which is the direction having the largest refractive index in the plane of the refractive index adjusting layer 13, is less than 45 ° (). Condition (e)). The smaller the angle θ, the more the in-plane refractive index distribution of the refractive index adjusting layer 13 shows the same tendency as the in-plane refractive index distribution of the light transmissive base material 12. .. That is, when this angle θ is less than 45 °, the sheet of the light-transmitting base material 12 is not only in the two directions of the slow-phase axial direction dx and the phase-advancing axial direction dy of the light-transmitting base material 12 described above. The refractive index in various directions along the surface does not change significantly between the functional layer 15 and the light-transmitting base material 12, and gradually changes in two steps. In particular, when this angle θ is 0 °, that is, when the slow-phase axial direction dx of the light-transmitting base material 12 and the slow-phase axial direction da of the refractive index adjusting layer 13 are parallel (condition (f)). The refractive index in each direction gradually changes between the functional layer 15 and the light-transmitting base material 12 in two steps, showing the same tendency as the change in the refractive index in different directions.
As a result, 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 in the traveling direction due to reflection while traveling to the light transmitting base material 12, and the interference fringes Can be made extremely effective and inconspicuous.

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

Further, the refractive index n _1x in the slow axial direction dx of the light transmissive base material 12, the refractive index n _1y in the phase advance axial direction dy of the light transmissive base material 13, and the slow axial direction da of the refractive index adjusting layer 13 It is preferable that the refractive index n _2a and the refractive index n _2b in the phase-advancing 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 adjusting layer 13 from having an unnecessarily strong birefringence, as in the case where the above-mentioned condition (d) is satisfied, thereby interfering. The stripes can be effectively made inconspicuous.

Further, along with one or more of the above-mentioned conditions (a) to (g), the in-plane average refractive index n ₁ (n ₁ = (n _1x + n _1y ) / 2) of the light transmissive base material 12 and the refractive index adjusting layer The in-plane average refractive index n ₂ (n ₂ = (n _2x + n _2y ) / 2) of 13 and the in-plane average refractive index n ₃ (n ₃ = (n _3x + n _3y ) / 2) of the functional layer 15 are ,
n ₁ <n ₂ <n ₃ or n ₁ > n ₂ > n ₃
It is preferable to satisfy the condition (h). When the condition (h) is satisfied, the refractive index adjusting layer 13 is imparted with appropriate birefringence, whereby the interference fringes can be effectively made inconspicuous.

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

Further, together with one or more of the above-mentioned conditions (a) to (h), the refractive index n _{1x of} the light-transmitting base material 12 in the slow-phase axial direction dx and the refractive index of the light-transmitting base material 12 in the phase-advancing axial direction dy. Refractive index n _1y , refractive index n _2x of the refractive index adjusting layer 13 in a direction parallel to the slow axial direction dx of the light transmissive base material 12, and refractive index in a direction parallel to the phase advance axial direction dy of the light transmissive base material 12. The refractive index n _2y of the rate adjusting layer 13, the refractive index n _3x of the functional layer 15 in the direction parallel to the slow axis direction dx of the light transmissive base material 12, and the phase advance axial direction dy of the light transmissive base material 12. The refractive index _n3y of the functional layer 15 in the direction parallel to
| 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 condition (i). When the condition (i) is satisfied, the refractive index difference between the refractive index adjusting layer 13 and the light transmissive base material 12 and the refractive index difference between the refractive index adjusting layer 13 and the functional layer 15 are large. As a result, the difference in refractive index from the light-transmitting base material 12 to the functional layer 15 can be changed little by little. As a result, the interference fringes can be effectively made inconspicuous.

By the way, retardation Re is known as an index showing the degree of in-plane birefringence. The retardation Re uses the refractive index n _max in the slow axis direction, which has the largest value, the refractive index n _{min in the} phase advance axis direction, which has the smallest value, and the thickness d (unit: nm) as follows. It is represented by.
Re [nm] = (n _max −n _min ) × d [nm]
As disclosed in Patent Document 1, from the viewpoint of preventing Nijimura, the laminated base material 11 preferably has a retardation of 3000 nm or more. Further, when the condition (d) and the condition (g) are satisfied, it is more preferable that the light-transmitting base material 12 has a retardation of 3000 nm or more. The retardation can be set to a measurement angle of 0 ° and a measurement wavelength of 589.3 nm using, for example, a KOBRA-WR manufactured by Oji Measuring Instruments, and can be set to a measured value. For retardation, the orientation axis direction (main axis direction) of the film is determined using two polarizing plates, and the refractive indexes (n _x , ny) of the two axes orthogonal to the orientation axis direction are determined. It was determined by a refractive index meter (NAR-4T manufactured by Atago Co., Ltd.). Here, an axis showing a higher refractive index is defined as a slow-phase axis. The film thickness d (nm) was measured using an electric micrometer (manufactured by Anritsu), and the unit was converted to nm. The retardation can also be calculated from the product of the difference in refractive index (n _{x −} n _y ) and the thickness d (nm) of the film.

From the viewpoint of setting the retardation of the light transmissive base material 12 to 3000 nm or more, the difference between the refractive index n _1x in the slow axis direction and the refractive index n _{1 y in the} phase advance axis direction of the light transmissive base material 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 required to obtain the above-mentioned retardation value becomes thick. On the other hand, if the refractive index difference Δn exceeds 0.20, the light-transmitting base material 12 is likely to be torn and torn, and its 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. When the refractive index difference Δn exceeds 0.15, the durability of the light-transmitting base material 12 in the moisture-heat resistance test may be inferior depending on the type of the light-transmitting base material 12. From the viewpoint of ensuring excellent durability in the moisture resistance test, the more preferable upper limit of the refractive index difference Δn is 0.12.

The refractive index n _1x of the light-transmitting base material 12 in the slow-phase axial direction dx is preferably 1.60 to 1.80, the more preferable lower limit is 1.65, and the more preferable upper limit is 1.75. Is. The refractive index n _1y of the light transmissive substrate 12 in the phase-advancing axial direction dy is preferably 1.50 to 1.70, with a more preferable lower limit of 1.55 and a more preferable upper limit of 1.62. (1.65). The refractive index n _1x in the slow axial direction dx and the refractive index n _1y in the phase advancing axial direction dy of the light transmissive base material 12 are in the above range, and the relationship of the refractive index difference Δn described above is satisfied. A more suitable inhibitory effect on Nijimura can be obtained.

By the way, the refractive index is calculated from the average reflectance (R) obtained by measuring the average reflectance (R) having a wavelength of 380 to 780 nm using a spectrophotometer (UV-3100PC manufactured by Shimadzu Corporation). It is specified using the formula of. For the average reflectance (R) of the functional layer 15, the raw material composition is applied onto a PET having a thickness of 50 μm without easy adhesion treatment to form a cured film having a thickness of 1 to 3 μm, and the raw material composition of PET is applied. A black vinyl tape (for example, Yamato vinyl tape NO200-38-21 38 mm width) with a width larger than the measurement spot area is attached to the missing surface (back surface) to prevent back surface reflection, and then the average reflection of each coating film is applied. The rate can be measured. The refractive index of the light transmissive base material 12 can be measured after similarly attaching a black vinyl tape to the surface opposite to the measurement surface. Further, the refractive index of the refractive index adjusting layer 13 can be measured after the black vinyl tape is attached 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 by using the above-mentioned Abbe refractive index meter 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 orientation axis direction (the direction of the main axis, that is, the direction of the slow axis in the plane and the phase advance axis) of the measurement target (light transmitting base material 12 or the refractive index adjusting layer 13) Orientation). Next, after attaching a black vinyl tape (for example, Yamato vinyl tape No200-38-21 38 mm width) to the back surface of the measurement target, a spectrophotometer (V7100 type, automatic absolute reflectance measurement unit, VAR-7010)
Using (Nippon Kogaku Co., Ltd.), the reflectance of the case where the vibration direction of the S-polarized light and the direction of the slow axis of the measurement target are parallel to each other is measured 5 times and the average value is calculated. In addition, the reflectance when the vibration direction of the S-polarized light and the direction of the phase-advancing axis of the measurement target are parallel is measured five times to calculate the average value. The average value of the reflectance when the vibration direction of S-polarized light and the direction of the slow axis of the measurement target are parallel is defined as the reflectance R (%) of the following equation, and the refractive index in the slow axis direction of the measurement target. It 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 laminated body 10, the cured film of each layer is scraped off with a cutter or the like to prepare a sample in a powder state, and JIS K7142 (2008) B method (powder or The Becke method (using a Cargill reagent having a known refractive index) according to the granular transparent material) is placed on a slide glass or the like, the reagent is dropped onto the sample, and the sample is immersed in the reagent. Observe the situation by microscopic observation, and use a bright line generated on the sample contour due to the difference in the refractive index of the sample and the reagent; the refractive index of the reagent at which the Becke line cannot be visually observed is used as the refractive index of the sample). Can be done. Since the refractive index of the light transmissive base material 12 and the refractive index adjusting layer 13 differs depending on the direction, the average reflectance is measured by attaching the black vinyl tape to the treated surface of the laminated base material 11 instead of the Becke method. Ask.

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

The material constituting the polyester base material can 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 polyesters include polyethylene terephthalate, polyethylene isophthalate, polybutylene terephthalate, poly (1,4-cyclohexylene methylene terephthalate), and polyethylene-2,6-naphthalate. Further, the polyester used for the polyester base material may be a copolymer of these polyesters, and the polyester is mainly used (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 it has a good balance of mechanical and optical properties. In particular, it is preferably made of polyethylene terephthalate (PET). This is because polyethylene terephthalate is highly versatile and easily available. Further, PET is excellent in transparency, thermal or mechanical properties, the retardation can be controlled by stretching, the intrinsic birefringence is large, and even if the film thickness is thin, a large retardation can be obtained relatively easily.

As a method for obtaining the polyester base material, for example, polyester such as PET as a material is melted, and unstretched polyester extruded into a sheet is transversely stretched at a temperature equal to or higher than the glass transition temperature using a tenter or the like, and then laterally stretched. A method of applying heat treatment can be mentioned. The transverse stretching temperature is preferably 80 to 130 ° C., more preferably 90 to 120 ° C. The lateral stretching ratio is preferably 2.5 to 6.0 times, more preferably 3.0 to 5.5 times. If the transverse stretching ratio exceeds 6.0 times, the transparency of the obtained polyester base material tends to decrease, and if the stretching ratio is less than 2.5 times, the stretching tension also decreases, so that the obtained polyester group is obtained. The birefringence of the material becomes small, and the film thickness for obtaining the desired retardation becomes thick. Further, when the polyester base material is extruded into a sheet, stretching in the flow direction (mechanical direction), that is, stretching in the longitudinal direction may be performed. In this case, from the viewpoint of stably securing the value of the refractive index difference Δn within the above-mentioned preferable range, the stretching ratio of the longitudinal stretching is preferably 2 times or less. Instead of longitudinally stretching during extrusion molding, longitudinal stretching may be performed after laterally stretching the unstretched polyester 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 base material produced by the above method to 3000 nm or more include a method of appropriately setting the stretching ratio, the stretching temperature, and the film thickness of the polyester base material to be produced. Specifically, for example, the higher the stretching ratio, the lower the stretching temperature, and the thicker the film thickness, the easier it is to obtain high retardation, and the lower the stretching ratio, the higher the stretching temperature, and the more the film thickness. The thinner the value, 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. If it is less than 15 μm, the retardation of the polyester base material cannot be made to 3000 nm or more, the anisotropy of the mechanical properties becomes remarkable, tears and tears are likely to occur, and the practicality as an industrial material is remarkably lowered. Sometimes. On the other hand, if it exceeds 500 μm, the polyester base material is very rigid, the flexibility peculiar to the polymer film is lowered, and the practicality as an industrial material is also lowered, which is not preferable. A more preferable lower limit of the thickness of the polyester base material is 50 μm, a more preferable upper limit is 400 μm, and a further preferable upper limit is 300 μm.

Further, the light-transmitting base material 12 preferably has a transmittance of 80% or more in the visible light region, and more preferably 84% or more. The transmittance can be measured by JISK7361-1 (a test method for the total light transmittance of a plastic-transparent material).

Further, the light transmissive base material 12 may be subjected to surface treatment such as saponification treatment, glow discharge treatment, corona discharge treatment, ultraviolet (UV) treatment, and flame treatment within a range not deviating from the gist of the present invention.

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

The refractive index adjusting layer 13 having in-plane birefringence formed on the light transmissive substrate 12 is formed by a layer formed by orienting a molecule having refractive index anisotropy (for example, a liquid crystal molecule) or a compound. obtain. Such a refractive index adjusting layer 13 is obtained by applying a composition containing a refractive index anisotropic molecule or a refractive index anisotropic compound onto a light-transmitting substrate 12 and curing the composition. As an example, when the light-transmitting base material 12 is made of a stretched film or the like and has a regular molecular orientation, the liquid crystal molecules coated on the light-transmitting base material 12 are the same. Due to its nature, it can be oriented with a regularity corresponding to the molecular orientation of the light-transmitting base material 12. As a result, the obtained refractive index adjusting layer 13 has in-plane birefringence corresponding to the birefringence of the light-transmitting base material 12, and the above-mentioned condition (a) is provided by the refractive index adjusting layer 13. ~ (I) can be satisfied. From the viewpoint of further stabilizing the orientation of the refractive index anisotropic molecule and the refractive index anisotropic compound contained in the refractive index adjusting layer 13, it does not depend only on the orientation of the light transmissive base material 12. The refractive index anisotropic molecule or the refractive index anisotropic compound contained in the refractive index adjusting layer 13 may be positively oriented by rubbing orientation or photoalignment.

Alternatively, as another method, the refractive index adjusting layer 13 having in-plane birefringence can be obtained by stretching the resin layer. In general, 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 adjusting layer 13 is formed on the light transmitting base material 12 before stretching, and the light transmitting base material 12 and the refractive index adjusting layer 13 are simultaneously stretched to birefringence the light transmitting base material 12. The property can be imparted, and the birefringence corresponding to the birefringence of the light transmissive base material 12 can also be imparted to the refractive index adjusting layer 13.

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

After that, the laminated base material 11 including the light transmitting base material 12 and the refractive index adjusting layer 13 formed on the light transmitting base material 12 is heated to a temperature equal to or higher than the glass transition temperature, and is laterally orthogonal to the mechanical direction. Stretch in the direction. As described above, when the stretching ratio in the horizontal direction is very large as compared with the stretching ratio in the vertical direction, the stretching axis of the light transmissive base material 12 is generally oriented in the horizontal direction, as a specific example. The slow axis of the light transmissive base material 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, even if the refractive index adjusting layer 13 is made of a resin material that is less likely to be imparted with birefringence than the light-transmitting base material 12, anisotropy corresponding to the birefringence of the light-transmitting base material 12 The birefringence in the above will be imparted to some extent.

According to the above method, the birefringence is imparted not only to the light-transmitting base material 12 but also to the refractive index adjusting layer 13 by the stretching process for imparting birefringence to the light-transmitting base material 12. Can be done. In addition, since the light transmitting base material 12 and the refractive index adjusting layer 13 are stretched in a heated state, the advantage of improving the adhesiveness between the light transmitting base material 12 and the refractive index adjusting layer 13 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 It can be appropriately set in relation to the refractive indexes n ₃ , n _3x , n _{3y of} n ₁ , n _1x , n _1y and the functional layer 15. As an example, when the light transmissive base material 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 set to 1.50 to 1.70. The refractive index n _2x of the refractive index adjusting layer 13 can be set to 1.55 to 1.75, and the refractive index n _2y of the refractive index adjusting layer 13 can be set to 1.45 to 1.65. The refractive index n _2a of the refractive index adjusting layer 13 can be 1.51 to 1.69, and the refractive index n _2b of the refractive index adjusting layer 13 can be 1.46 to 1. It can be .64.

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

The thickness (at the time of curing) of the refractive index adjusting layer 13 is, for example, a measured value of any 10 points obtained by observing the cross section of the refractive index adjusting layer 13 with an electron microscope (SEM, TEM, STEM). Can be specified as the mean value (nm) of. When the thickness of the refractive index adjusting layer 13 is very thin, it can be measured by recording a high-magnification observation as a photograph and further enlarging it. When enlarged, the layer interface line, which was so thin that it can be clearly seen as a boundary line, becomes a thick line. In that case, the central portion obtained by dividing the thick line width into two equal parts may be measured as the boundary line.

<Functional layer, 2nd 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 intended to exert some function in the laminated body 10, and specifically, for example, hard coat property, antireflection property, antistatic property, or Examples include layers that exhibit functions such as antifouling properties. As described above, the number of functional layers included in the laminated body 10 can be any number of one or more depending on the use of the laminated body and the like. In the laminated body 10 shown in FIG. 1, the functional layer 15 is composed of a hard coat layer formed on one surface of the laminated base material 11. Further, in the laminated body 10 shown in FIG. 2, the functional layer 15 is composed of a hard coat layer formed on one surface of the laminated base material 11, and the second functional layer 17 is a hard coat layer. It is composed of a low refractive index layer formed on a surface opposite to that of the laminated base material 11. 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, and specifically, in the pencil hardness test (4.9 N load) specified in JIS K5600-5-4 (1999), " A layer having a hardness of "H" or higher is preferable. As an example of the hard coat layer, a composition for forming a hard coat layer containing an ionizing radiation curable resin which is a resin cured by ultraviolet rays or an electron beam and a photopolymerization initiator is applied onto the laminated base material 11 and laminated. 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 index _n 3 of the functional layer 15 composed of the hard coat _layer, n _{3x, n 3y} are the same value. Specifically, the refractive indexes n ₃ , n _3x , and n _3y of the functional layer 15 made of the hard coat layer can be set to 1.45 to 1.65, respectively. The film thickness (when cured) of the hard coat layer is in the range of 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 a cross section with an electron microscope (SEM, TEM, STEM).

Examples of the ionizing radiation curable resin of the composition for forming a hard coat layer include compounds having one or two or more unsaturated bonds such as compounds having an acrylate-based functional group. Examples of the compound having an unsaturated bond of 1 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 polymethylol propantri (meth) acrylate, hexanediol (meth) acrylate, tripropylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, and pentaerythritol tri (). Polyfunctional compounds such as meta) acrylate, dipentaerythritol hexa (meth) acrylate, 1,6-hexanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, or the above polyfunctional compound and (meth) acrylate. Reaction products such as (for example, poly (meth) acrylate ester of polyhydric alcohol), and the like. In addition, in this specification, "(meth) acrylate" refers to methacrylate and acrylate.

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

The above-mentioned ionizing radiation curable resin is used in combination with a solvent-drying resin (a resin such as a thermoplastic resin that forms a film simply by drying a solvent added to adjust the solid content at the time of coating). You can also do it. By using a solvent-drying resin together, it is possible to effectively prevent coating defects on the coated surface. The solvent-drying resin that can be used in combination with the ionizing radiation curable resin is not particularly limited, and in general, a thermoplastic resin can be used. The thermoplastic resin is not particularly limited, and 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, and a polyester resin. Examples thereof include resins, polyamide resins, cellulose derivatives, silicone resins and rubbers or elastomers. The thermoplastic resin is preferably non-crystalline and soluble in an organic solvent (particularly a common solvent capable of dissolving a plurality of polymers and curable compounds). In particular, from the viewpoint of film-forming property, transparency and weather resistance, styrene resin, (meth) acrylic resin, alicyclic olefin resin, polyester resin, cellulose derivative (cellulose ester, etc.) and the like are preferable.

Further, the composition for forming a hard coat layer may contain a thermosetting resin. The thermosetting resin is not particularly limited, and for example, phenol resin, urea resin, diallyl phthalate resin, melamine resin, guanamine resin, unsaturated polyester resin, polyurethane resin, epoxy resin, aminoalkyd resin, and melamine-urea cocondensation. Examples thereof include resins, silicon resins, and polysiloxane resins.

The photopolymerization initiator is not particularly limited, and known photopolymerization initiators can be used. For example, specific examples of the photopolymerization initiator include acetophenones, benzophenones, Michler benzoylbenzoates, and α-amilo. Examples thereof include xim esters, thioxanthones, propiophenones, benzyls, benzoins, and acylphosphine oxides. Further, it is preferable to use a photosensitizer in combination, 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 radically polymerizable unsaturated group, acetophenones, benzophenones, thioxanthones, benzoins, benzoin methyl ethers and the like are used alone or mixed. It is preferable to use it. When the ionizing radiation curable resin is a resin system having a cationically polymerizable functional group, the photopolymerization initiator includes an aromatic diazonium salt, an aromatic sulfonium salt, an aromatic iodonium salt, a metallocene compound, and a benzoin sulfone. It is preferable to use an acid ester or the like alone or as a mixture.

The content of the photopolymerization initiator in the composition for forming a hard coat layer is preferably 1 to 10 parts by mass with respect to 100 parts by mass of the ionizing radiation curable resin. If it is less than 1 part by mass, the hardness of the hard coat layer in the laminated body 10 may not be sufficient, and if it exceeds 10 parts by mass, the ionizing radiation does not reach the deep part of the coated film and the inside This is because curing may not be promoted. The more preferable lower limit of the content of the photopolymerization initiator is 2 parts by mass, and the more preferable upper limit is 8 parts by mass. When the content of the photopolymerization initiator is in this range, the hardness distribution does not occur in the film thickness direction, and the hardness tends to be uniform.

The composition for forming a hard coat layer may contain a solvent. The solvent can be selected and used according to the type 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.), Carbon halides (dichloromethane, dichloroethane, etc.), esters (methyl acetate, ethyl acetate, butyl acetate, etc.), water, alcohols (ethanol, isopropanol, butanol, cyclohexanol, etc.), cellosolves (methylcellosolve, ethylcellosolve, etc.) ), Cellosolve acetates, sulfoxides (dimethyl sulfoxide, etc.), amides (dimethylformamide, dimethylacetamide, etc.) and the like, and these may be mixed solvents.

The content ratio (solid content) of the raw material in the composition for forming the hard coat layer is not particularly limited, but is usually 5 to 70% by mass, particularly preferably 25 to 60% by mass.

The composition for forming a hard coat layer includes conventionally known dispersants, depending on the purpose of increasing the hardness of the hard coat layer, suppressing curing shrinkage, controlling the refractive index, imparting antiglare property, and the like. Surfactants, antistatic agents, silane coupling agents, thickeners, color inhibitors, colorants (pigments, dyes), defoamers, leveling agents, flame retardants, UV absorbers, adhesives, polymerization inhibitors , Antioxidant, surface modifier, slipper, etc. may be added.

Further, the composition for forming a hard coat layer may be used by mixing a photosensitizer, and specific examples thereof include n-butylamine, triethylamine, poly-n-butylhosophine and the like. ..

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, and for example, a known device such as a paint shaker, a bead mill, a kneader, or a mixer can be used.

The method for applying the composition for forming a hard coat layer onto the laminated base material 11 is not particularly limited, and for example, a spin coating method, a dip method, a spray method, a die coating method, a bar coating method, a roll coater method, and the like. Known methods such as a meniscus coater method, a flexographic printing method, a screen printing method, and a speed coater method can be mentioned.

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

Examples of the above-mentioned activation energy ray irradiation include irradiation with ultraviolet rays or electron beams. Specific examples of the ultraviolet source include light sources such as ultra-high pressure mercury lamps, high pressure mercury lamps, low pressure mercury lamps, carbon arc lamps, black light fluorescent lamps, and metal halide lamps. Further, as the wavelength of ultraviolet rays, a wavelength range of 190 to 380 nm can be used. Specific examples of the electron beam source include various electron beam accelerators such as a cockcroftwald type, a bandegraft type, a resonance transformer type, an insulated core transformer type, or 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 lowering the reflectance when light from the outside (for example, fluorescent lamp, natural light, etc.) is reflected on the surface of the laminated body 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, and 1.3. It is more preferably in the range of ~ 1.6. When the refractive index of the low refractive index layer is within the above range, reflection on the laminated body 10 can be effectively prevented. Further, the refractive index of the low refractive index layer is gradually directed toward the refractive index of air in the low refractive index layer from the inner side of the laminated body 10 toward the surface side of the laminated body 10. It may be something that is changing.

The material used for the low refractive index layer is not particularly limited as long as it can form the low refractive index layer having the above-mentioned refractive index. For example, the resin material described in the above-mentioned composition for forming a hard coat layer. Is preferably contained. Further, the refractive index of the low refractive index layer can be adjusted by containing a silicone-containing copolymer, a fluorine-containing copolymer, and fine particles in addition to the resin material. Examples of the silicone-containing copolymer include a silicone-containing vinylidene copolymer. Moreover, as a specific example of the said fluorine-containing copolymer, for example, a copolymer obtained by copolymerizing a monomer composition containing vinylidene fluoride and hexafluoropropylene can be mentioned. In addition, 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 "fine particles having voids" means a structure in which a gas is filled inside the fine particles and / or a porous structure containing the gas, and the occupancy rate of the gas in the fine particles is higher than the original refractive index of the fine particles. It means fine particles whose refractive index decreases in inverse proportion to.

Here, an example 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 is shown, but the present invention is not limited to these examples, and the laminate 10 is hard coated. 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 try to avoid it.

The antistatic layer can be formed, for example, by including an antistatic agent in the composition for forming a hard coat layer. 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 be done. When the above antistatic agent is used, its content is preferably 1 to 30% by mass with respect to the total mass of the total solid content.

Further, the antiglare layer can be formed, for example, by including an antiglare agent in the composition for forming a hard coat layer. 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 is generally set to about 0.01 to 20 μm. Further, the shape of the fine particles may be any of a true spherical shape, an elliptical shape, and the like, and a true spherical shape is preferable.

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 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 can be mentioned.

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

The main purpose of the antifouling agent is to prevent stains on the outermost surface of the liquid crystal display device, and it is also possible to impart scratch resistance to the liquid crystal display device. Examples of the antifouling agent include a fluorine-based compound, a silicon-based compound, or a mixed compound thereof. More specifically, a silane coupling agent having a fluoroalkyl group such as 2-perfluorooctylethyltriaminosilane can be mentioned, and in particular, one having an amino group can be preferably used. The resin is not particularly limited, and examples thereof include the resin materials exemplified in the above-mentioned composition for forming a hard coat layer.

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

<About laminated base material and laminated body>
According to the laminated base material 11 and the laminated body 10 described above as one embodiment, between the functional layer 15 provided on the laminated base material 11 and the light transmitting base material 12 of the laminated base material 11. Is provided with a refractive index adjusting layer 13. The refractive index of the refractive index adjusting layer 13 has in-plane birefringence, and is of the slow-phase axial direction dx and the phase-advancing axial direction dy of the light-transmitting base material 12 also having in-plane birefringence. The refractive index along both directions is adjusted between the light transmitting base material 12 and the functional layer 15. More specifically, there is no optical interface between the light-transmitting base material 12 and the functional layer 15 in which the refractive index of the light-transmitting base material 12 changes significantly in the slow-phase axial direction dx, and light There is no optical interface in which the refractive index of the transmissive base material 12 changes significantly in the phase-advancing axis direction dy. That is, there is no interface between the light transmissive base material 12 and the functional layer 15 because the difference in refractive index is large and the reflectance becomes high. Therefore, it is possible to effectively prevent the light incident into the laminated body 10 from the side of the functional layer 15 but being reflected by the time it reaches the light transmissive base material 12 having in-plane birefringence. Can be done. As a result, it is possible to effectively make 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 inside the laminated body 10 inconspicuous.

Further, by setting the retardation of the light transmissive base material 12 to 3000 nm or more, it is possible to make Nijimura inconspicuous. Therefore, according to the laminated base material 11 and the laminated body 10 described here, both the Nijimura and the interference fringes can be effectively made inconspicuous.

Further, if the refractive index adjusting layer 13 is realized by the primer layer, the above-mentioned useful effects can be ensured without causing a substantial increase in material cost, an increase in the manufacturing process, or the like. .. However, the thickness is not limited to such an example, and the thickness of at least one between the light transmissive substrate 12 and the refractive index adjusting layer 13 and between the refractive index adjusting layer 13 and the functional layer 15 is less than 30 nm. The primer layer may be provided separately from the refractive index adjusting layer 13. Even when a primer layer having a thickness of less than 30 nm is provided, the effect of making the interference fringes of the above-mentioned refractive index adjusting layer 13 inconspicuous 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, for example, by incorporating them into the polarizing plate 20. FIG. 5 is a schematic configuration diagram of a polarizing plate 20 incorporating the laminated body 10 and the laminated base material 11 shown in FIG. As shown in FIG. 5, the polarizing plate 20 includes a laminate 10, a polarizing element 21, and a protective film 22. The polarizing element 21 is formed on a 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 a surface opposite to the surface on which the laminate 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 dyed and stretched with iodine and the like, a polyvinyl formal film, a polyvinyl acetal film, an ethylene-vinyl acetate copolymerization system saponified film, and the like.

≪Liquid crystal display 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 a liquid crystal display panel 30 incorporating the laminated body 10 and the laminated base material 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, and adhesion from the light source side (backlight unit side) to the observer side. It has a structure in which 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 laminated in this order. The liquid crystal cell 35 has a liquid crystal layer, an alignment film, an electrode layer, a color filter, and the like arranged 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 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. FIG. 7 is an example of an image display device 40 incorporating the laminated body 10 and the laminated base material 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.

The image display device 40 shown in FIG. 7 is a liquid crystal display. The image display device 30 is composed of a backlight unit 41 and a liquid crystal display panel 30 including a laminated body 10 arranged on the observer side of the backlight unit 41. As the backlight unit 41, a known backlight unit can be used.

≪Other uses≫
Further, the above-mentioned laminated base material 11 and the laminated body 10 may be provided on the image display device 30 via a touch panel sensor as an application other than the 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 directly on the touch panel sensor or via a member is prepared in advance, and the touch panel device is provided on the image display device. It may be.

Further, the above-mentioned laminated base material 11 and the laminated body 10 can be used in various applications in which the occurrence 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 clock or meters.

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

As described below, the laminates according to Examples 1 and 2 and Comparative Example 1 were produced. The occurrence of interference fringes and the occurrence of Nijimura were investigated for each of the produced laminates.

(Example 1)
The polyethylene terephthalate material was melted at 290 ° C., extruded into a sheet through a film forming die, and cooled by being brought into close contact with a water-cooled rotary quenching drum to prepare an unstretched film. This unstretched film is preheated at 120 ° C. for 1 minute in a biaxial stretching test device (manufactured by Toyo Seiki Co., Ltd.), then stretched at 120 ° C. at a stretching ratio of 4.5 times, and then the stretching direction is 90. Stretching was carried out in the direction of degree at a stretching ratio of 1.5 times to obtain a light-transmitting substrate having n _1x = 1.70, n _1y = 1.60, a film thickness of 80 μm, and a retardation of 8000 nm.

A photopolymerizable liquid crystal compound was dissolved in a mixed solvent of cyclohexanone and n-propyl alcohol (solvent ratio 9: 1) in an amount of 20% by mass on a light-transmitting substrate, and a photopolymerization initiator Irg184 (Ciba Specialty Chemicals Co., Ltd.) was dissolved. The ink obtained by adding 5% of)) to the solid content was coated with a bar coater so that the film thickness after drying was 0.5 μm. Next, the solvent was dried and removed by heating at 70 ° C. for 4 minutes, the photopolymerizable liquid crystal compound was oriented, and the coated surface was further irradiated with ultraviolet rays to immobilize the photopolymerizable liquid crystal compound. The refractive index adjusting layers of n _2x = 1.60 and n _2y = 1.55 were laminated.

Next, as a functional layer, pentaerythritol triacrylate (PETA), which is optically isotropic, was dissolved in a MIBK solvent in an amount of 30% by mass, and a photopolymerization initiator Irg184 (Ciba Specialty Chemicals Co., Ltd.) was added. The ink to which 5% was added to the solid content was coated with a bar coater so that the film thickness after drying was 5 μm. Next, it was heated at 70 ° C. for 2 minutes to remove the solvent, and the coated surface was fixed by irradiating the coated surface with ultraviolet rays, and a functional layer of n _3x = n _3y = 1.50 was laminated, and according to Example 1. A laminate was obtained.

(Example 2)
The polyethylene terephthalate material was melted at 290 ° C., extruded into a sheet through a film forming die, and cooled by being brought into close contact with a water-cooled rotary quenching drum to prepare an unstretched film. This unstretched film is preheated at 120 ° C. for 1 minute in a biaxial stretching test device (manufactured by Toyo Seiki Co., Ltd.), then stretched at 120 ° C. at a stretching ratio of 4.5 times, and then the stretching direction is 90. Stretching was carried out in the direction of degree at a stretching ratio of 1.5 times to obtain a light-transmitting substrate having n _1x = 1.70, n _1y = 1.60, a film thickness of 33 μm, and a retardation of 3300 nm. A refractive index adjusting layer and a functional layer were formed on the obtained light-transmitting substrate in the same manner as in Example 1 to obtain a laminate according to Example 2. That is, the laminate according to Example 2 has a different thickness of the light-transmitting base material from the laminate according to Example 1.

(Comparative Example 1)
Comparative Example in the same manner as the laminate according to Example 1 except that an intermediate layer composed of pentaerythritol triacrylate: antimony pentoxide = 7: 3 was used instead of the refractive index adjusting layer of Example 1. The laminate according to No. 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 into a sheet through a film forming die, and cooled by being brought into close contact with a water-cooled rotary quenching drum to prepare an unstretched film. This unstretched film is preheated at 120 ° C. for 1 minute in a biaxial stretching test device (manufactured by Toyo Seiki Co., Ltd.), then stretched at 120 ° C. at a stretching ratio of 4.5 times, and then the stretching direction is 90. Stretching was carried out in the direction of degree at a stretching ratio of 1.5 times to obtain a light-transmitting substrate having n _1x = 1.70, n _1y = 1.60, a film thickness of 28 μm, and a retardation of 2800 nm. A refractive index adjusting layer and a functional layer were formed on the obtained light-transmitting substrate 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 has a different thickness of the light-transmitting base material from the laminate according to Example 1.

(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 orientation axis direction of the film is determined from the stretched light-transmitting substrate using two polarizing plates, and the refractive index (nx, ny) of the two axes orthogonal to the orientation axis direction with respect to the wavelength of 590 nm. Was determined by an Abbe refractive index meter (NAR-4T manufactured by Atago Co., Ltd.). Here, an axis showing a higher refractive index is defined as a slow-phase 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 difference in refractive index (n _1x −n _1y ) and the thickness d (nm) of the film.

(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 coated on an optically isotropic glass substrate and subjected to a rubbing treatment. An ink obtained by dissolving 20% by mass of a photopolymerizable liquid crystal compound on this substrate in a mixed solvent of cyclohexanone and n-propyl alcohol (solvent ratio 9: 1) was prepared by a spin coater to have a film thickness of 1 um after drying. It was applied so as to be. Next, the photopolymerizable liquid crystal compound was fixed and obtained by heating at 70 ° C. for 4 minutes to dry and remove the solvent, orienting the photopolymerizable liquid crystal compound, and further irradiating the coated surface with ultraviolet rays. The refractive index of the refractive index adjusting layer was measured in the same manner as that of the light transmitting substrate.

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

(Measurement of refractive index of isotropic material)
The refractive index of the isotropic material (intermediate layer and functional layer) was measured by an Abbe refractive index meter (NAR-4T manufactured by Atago).

(Evaluation of interference fringes)
The occurrence of interference fringes in each laminate was evaluated as follows. Using an interference fringe inspection lamp (Na lamp) manufactured by Funatec, the presence or absence of interference fringes in the visually obtained antiglare film was inspected and evaluated according to the following criteria. The obtained antiglare film was evaluated by coating the opposite side of the coated surface with black ink, applying an interference fringe inspection lamp to the coated surface, and observing reflection.
◯: Interference fringes are observed, but they are extremely thin and have no problem in actual use.
X: Interference fringes are clearly observed.

(Nijimura evaluation)
The occurrence of Nijimura in each sample was evaluated as follows. Each laminated substrate was placed on a polarizing element on the observer side of an LED-backlit liquid crystal monitor (FLATORON IPS226V (manufactured by LG Electronics Japan)) to produce a liquid crystal display device. It was arranged so that the angle formed by the slow axis of the polyester base material and the absorption axis of the polarizing element on the observer side of the liquid crystal monitor was 45 °. Then, in a dark place and a bright place (illuminance around the LCD monitor 400 lux), the displayed image is visually observed and observed through polarized sunglasses from the front and diagonal direction (about 50 degrees), and the presence or absence of Nijimura is evaluated according to the following criteria. did. Observation through polarized sunglasses is a much stricter evaluation method than visual observation. The observation was carried out by 10 people, and the largest number of evaluations were the observation results.
◎: Nijimura is not observed ○: Nijimura is observed, but there is no problem in actual use ×: Nijimura is strongly observed

Table 1 shows the evaluation results of the interference fringes and Nijimura.

Claims (16)

Laminated substrate and
A functional layer provided on one surface of the laminated base material is provided.
The laminated base material is
With an in-plane birefringent light-transmitting substrate,
A light-transmitting base material which is laminated with the light-transmitting base material and has in-plane double refractive index, and is located between the light-transmitting base material and the functional layer to form the light-transmitting base material. It is provided with a refractive index adjusting layer that reduces the difference in refractive index of the interface existing between the functional layer and the light-transmitting substrate to be smaller than the difference in refractive index between the light-transmitting base material and the functional layer .
The refractive index n _1x in the slow axis direction, which is the direction in which the refractive index is the largest in the plane of the light transmissive substrate, and the refractive index adjusting layer in the direction parallel to the slow axis direction of the light transmissive substrate. The refractive index n _{2x of} the functional layer and the refractive index n _{3x of the} functional layer in the direction parallel to the slow axis direction of the light transmissive substrate.
n _1x > n _2x > n _3x
Satisfy the relationship
The refractive index n _1y in the phase-advancing axis direction orthogonal to the slow-phase axis direction of the light-transmitting base material, and the refractive index of the refractive index adjusting layer in the direction parallel to the phase-advancing axis direction of the light-transmitting base material. n _2y and the refractive index n _{3y of the} functional layer in the direction parallel to the phase advance axis direction of the light transmissive substrate are
n _1y <n _2y <n _3y
A laminated body that satisfies the relationship. The laminate according to claim 1, wherein the functional layer is optically isotropic. When the laminated base material is observed from the normal direction, the refractive index adjusting layer is the direction in which the light transmissive base material has the slowest axial direction and the refractive index having the largest value in the plane of the refractive index adjusting layer. The laminate according to claim 1 or 2, wherein the magnitude of the angle formed by the slow axis direction of the above is less than 45 °. The slow axis direction of the light transmissive substrate is parallel to the slow axis direction of the refractive index adjusting layer, which is the direction having the largest refractive index in the plane of the refractive index adjusting layer. The laminate according to any one of 1 to 3. The refractive index n _{1x of} the light-transmitting base material in the slow-phase axial direction, the refractive index n _{1y of} the light-transmitting base material in the phase-advancing axis direction, and the highest refractive index in the plane of the refractive index adjusting layer. The refractive index n _2a in the slow axis direction of the refractive index adjusting layer, which is the direction, and the refractive index n _2b in the phase advance axis direction of the refractive index adjusting layer orthogonal to the slow axis direction of the refractive index adjusting layer. But,
The laminate according to claim 3 or 4, which satisfies the relationship (n _1x −n _1y )> (n _2a −n _2b ). The refractive index n _{1x of} the light transmitting substrate in the slow axis direction, the refractive index n _2x of the refractive index adjusting layer in the direction parallel to the slow axis direction dx of the light transmitting substrate, and The refractive index n _{3x of the} functional layer in the 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) |
The refractive index n _{1y of} the light-transmitting substrate in the phase-advancing axis direction, the refractive index n _2y of the refractive index adjusting layer in the direction parallel to the phase-advancing axis direction of the light-transmitting substrate, and the light. The refractive index _{n3y of the} functional layer in the direction parallel to the phase-advancing axis direction of the permeable base material is
Claim that satisfies the relationship of n ₂ = (n _2x + n _2y ) / 2 and | n _2y − ((n _1y + n _3y ) / 2) | <| n ₂ − ((n _1y + n _3y ) / 2) | Item 2. The laminate according to any one of Items 1 to 5. The laminate according to any one of claims 1 to 6, wherein the laminated substrate has a retardation of 3000 nm or more. The laminate according to any one of claims 1 to 6, wherein the light-transmitting substrate has a retardation of 3000 nm or more. The laminate according to any one of claims 1 to 8, wherein the functional layer is a hard coat layer. The laminate according to any one of claims 1 to 9, further comprising a second functional layer provided on the side of the functional layer opposite to the laminated base material side. The laminate according to claim 10, wherein the second functional layer is a low refractive index layer having a refractive index lower than that of the functional layer. Polarizing element and
A polarizing plate comprising the laminate according to any one of claims 1 to 11. A liquid crystal display panel comprising the laminate according to any one of claims 1 to 11 or the polarizing plate according to claim 12. An image display device comprising the laminate according to any one of claims 1 to 11 or the polarizing plate according to claim 12. A method of using a functional layer by laminating on one surface of a laminated base material.
The laminated base material is
With an in-plane birefringent light-transmitting substrate,
A refractive index adjustment layer having birefringence of the light transmitting substrate with the laminated plane, the said light transmitting substrate is positioned between the functional layer and the light transmitting substrate It is provided with a refractive index adjusting layer that reduces the difference in refractive index of the interface existing between the functional layer and the light-transmitting substrate to be smaller than the difference in refractive index between the light-transmitting base material and the functional layer .
The refractive index n _1x in the slow axis direction, which is the direction in which the refractive index is the largest in the plane of the light transmissive substrate, and the refractive index adjusting layer in the direction parallel to the slow axis direction of the light transmissive substrate. The refractive index n _{2x of} the functional layer and the refractive index n _{3x of the} functional layer in the direction parallel to the slow axis direction of the light transmissive substrate.
n _1x > n _2x > n _3x
Satisfy the relationship
The refractive index n _1y in the phase-advancing axis direction orthogonal to the slow-phase axis direction of the light-transmitting base material, and the refractive index of the refractive index adjusting layer in the direction parallel to the phase-advancing axis direction of the light-transmitting base material. n _2y and the refractive index n _{3y of the} functional layer in the direction parallel to the phase advance axis direction of the light transmissive substrate are
n _1y <n _2y <n _3y
How to use the functional layer that satisfies the relationship. A step of laminating a functional layer on one surface of a laminated base material is provided.
The laminated base material is
With an in-plane birefringent light-transmitting substrate,
A refractive index adjustment layer having birefringence of the light transmitting substrate with the laminated plane, the said light transmitting substrate is positioned between the functional layer and the light transmitting substrate It is provided with a refractive index adjusting layer that reduces the difference in refractive index of the interface existing between the functional layer and the light-transmitting substrate to be smaller than the difference in refractive index between the light-transmitting base material and the functional layer .
The refractive index n _1x in the slow axis direction, which is the direction in which the refractive index is the largest in the plane of the light transmissive substrate, and the refractive index adjusting layer in the direction parallel to the slow axis direction of the light transmissive substrate. The refractive index n _{2x of} the functional layer and the refractive index n _{3x of the} functional layer in the direction parallel to the slow axis direction of the light transmissive substrate.
n _1x > n _2x > n _3x
Satisfy the relationship
The refractive index n _1y in the phase-advancing axis direction orthogonal to the slow-phase axis direction of the light-transmitting base material, and the refractive index of the refractive index adjusting layer in the direction parallel to the phase-advancing axis direction of the light-transmitting base material. n _2y and the refractive index n _{3y of the} functional layer in the direction parallel to the phase advance axis direction of the light transmissive substrate are
n _1y <n _2y <n _3y
A method for manufacturing a laminate that satisfies the above relationship.

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