KR102000511B1 - Light diffusion film - Google Patents

Abstract

It is an object of the present invention to provide a light diffusion film in which the diffusion area of incident light is effectively widened by diffusing incident light not only in the direction along its longitudinal direction but also in a direction orthogonal to its longitudinal direction.
In order to solve such a problem, a long luminescent diffusion film having a first louver structure and a second louver structure successively from below in accordance with the film thickness direction, wherein the first louver structure and the second louver structure each have a refractive index And a plurality of plate-shaped regions having different refractive indexes are alternately arranged in an arbitrary one direction along the film surface, and the film is formed in a louver structure. When viewed from above the film, The acute angle? 1 formed by the extending direction of the plate-shaped area in the first louver structure and the extending direction of the plate-shaped area in the second louver structure is set to a value within a range of 10 to 90 degrees.

Description

LIGHT DIFFUSION FILM

The present invention relates to a light diffusion film.

In particular, the present invention relates to a light diffusion film in which the diffusion area of incident light is effectively widened by diffusing incident light not only in a direction along its longitudinal direction but also in a direction orthogonal to its longitudinal direction.

Conventionally, for example, in an optical technology field to which a liquid crystal display device or the like belongs, a light diffusion film capable of diffusing incident light in a specific direction in a specific direction and directly transmitting incident light in other directions Use has been proposed.

Various light-diffusing films are known, but in particular, a light-diffusing film having a louver structure in which a plurality of plate-like regions having different refractive indexes are alternately arranged in an arbitrary one direction along the film surface is widely used (For example, Patent Documents 1 and 2).

That is, Patent Document 1 discloses a light control plate (light diffusion film) which is a plastic sheet, which selectively scatters incident light of two or more angular ranges with respect to the sheet.

Patent Document 1 discloses that a resin composition consisting of a plurality of compounds having at least one polymerizable carbon-carbon double bond in a molecule having a difference in refractive index is kept in a film form and irradiated with ultraviolet rays in a specific direction, And a second step of holding the resin composition in the form of a film on the obtained cured product and irradiating ultraviolet rays in a direction different from that of the first step to cure the resin composition, and if necessary, repeating the second step (Light diffusing film).

In Patent Document 2, there is an angle dependency of the clouding value, and when light is incident on the surface at an angle of 0 to 180 degrees, a light scattering angle range (light diffusion angle of incidence angle As shown in Figs. 24 (a) to 24 (b), a plurality of light control films (light diffusion films) are formed by laminating a plurality of light control films Diffusion film) is laminated so that the directions of light scattering angles (light diffusion angle of incidence angles) are almost perpendicular to each other.

Japanese Patent Application Laid-Open No. 63-309902 (claims) Japanese Patent Application Laid-Open No. 2005-316354 (claims)

However, in Patent Document 1, in the case where the light diffusion film is continuously mass-produced continuously, a coating layer composed of the composition for a light diffusion film is moved to a conveyor or the like, and an active energy ray The light diffusion film having a predetermined louver structure is produced.

In the case of Patent Document 1, it is possible to obtain a light-diffusing film for diffusing incident light in the moving direction of the applied layer, that is, in the direction along the longitudinal direction of the film. However, A light diffusing film can not be obtained.

More specifically, in order to obtain a light diffusion film for diffusing incident light in a direction orthogonal to the longitudinal direction of the film, it is necessary to form a louver structure comprising a plate-like region extending in the longitudinal direction of the film.

Therefore, in order to form such a louver structure in Patent Document 1, a linear light source is arranged such that the long axis direction of the linear light source is in the direction corresponding to the moving direction of the application layer.

However, even when the linear light sources are arranged as such, the active energy rays from the linear light sources are irradiated at different angles by the angular positions in the width direction on the surface of the coating layer when viewed from the end face in the moving direction of the coating layer As a result, the light diffusion property of the resulting light diffusion film becomes uneven.

Therefore, in Patent Document 1, in order to obtain an elongated light diffusion film for diffusing incident light in a direction orthogonal to its longitudinal direction, first, when a film is viewed from above, a plate-like region is arranged along the width direction It is necessary to obtain a light diffusion film having a louver structure. Then, it is necessary to cut them and change the direction of 90 DEG to connect a plurality of light diffusion films. For this reason, there has been a problem that the light diffusing property becomes uneven in the joint portion or the strength of the film tends to be lowered.

The substantially disclosed in Patent Document 1 is that the extending direction of the plate-shaped region in the louver structure obtained in the first step and the extending direction of the plate-shaped region in the louver structure obtained in the second step are the film width It is basically parallel in direction.

For this reason, there is a problem that it is fundamentally impossible to diffuse the incident light in the direction along the longitudinal direction, but also to diffuse the light perpendicular to the longitudinal direction.

On the other hand, in Patent Document 2, as shown in Figs. 24 (a) to (b), two of the plurality of light diffusion films are laminated so that the directions of the light diffusion angle of incidence angles are almost orthogonal, It is considered that light can be diffused not only in the direction along the longitudinal direction but also in the direction orthogonal to the longitudinal direction.

However, even in the case of Patent Document 2, in the case where the light diffusion film is continuously mass-produced, the active energy ray is irradiated using the linear light source while moving the coating layer made of the composition for the light diffusion film to a conveyor or the like.

Therefore, it is difficult to obtain the light diffusion film 221 that diffuses the incident light in the direction orthogonal to the longitudinal direction of the film, as shown in Fig. 24 (a), for the same reason as in the case of Patent Document 1.

Therefore, even in the case of the light diffusion film disclosed in Patent Document 2, in order to obtain an elongated light diffusion film 221 for diffusing incident light as shown in Fig. 24 (a) in a direction orthogonal to the longitudinal direction thereof , It is necessary to connect a plurality of light diffusion films, so that the light diffusing property becomes uneven in the joint portion as in the case of Patent Document 1, or the strength of the film tends to be lowered.

For this reason, there has been a problem that the diffusion area of the incident light can not be effectively expanded by causing the incident light to be diffused not only in the direction along the longitudinal direction but also in the direction orthogonal to the longitudinal direction.

Under such circumstances, it has been desired to provide a long-lived light diffusion film which can be easily provided on a large-screen screen or the like and does not cause problems such as seams.

That is, there has been a demand for an elongated light diffusion film that effectively diffuses the incident light by diffusing not only the light in the longitudinal direction but also the direction orthogonal to the longitudinal direction.

Therefore, the inventors of the present invention have made an effort to give an example in consideration of the above-described circumstances, and by carrying out the predetermined manufacturing method, it is possible to prevent the extension direction of the plateau region in the first louver structure, And a longitudinal direction of the plate-shaped region of the light-diffusing film is crossed at a predetermined angle, thereby completing the present invention.

That is, an object of the present invention is to provide a light source that effectively diffuses incident light by diffusing incident light not only in a direction along its longitudinal direction but also in a direction orthogonal to its longitudinal direction, And to provide a diffusion film.

According to the present invention, there is provided a long-lived light diffusion film having a first louver structure and a second louver structure successively from below in accordance with the film thickness direction, wherein the first louver structure and the second louver structure have a plurality of And a plurality of plate-like regions having different refractive indexes are alternately disposed in parallel in an arbitrary one direction along the film surface. Further, when viewed from above the film, the first louver structure Wherein an acute angle &thetas; 1 between the extending direction of the plate-shaped area in the first louver structure and the extending direction of the plate-shaped area in the second louver structure is set to a value within a range of 10 to 90 DEG, One problem can be solved.

That is, in the light diffusion film of the present invention, since the extending direction of the plate-shaped area in the first louver structure and the extending direction of the plate-shaped area in the second louver structure are crossed at a predetermined angle, The diffusion area of the incident light can be effectively widened by not only the direction along the longitudinal direction but also the direction orthogonal to the longitudinal direction.

Further, in the construction of the light diffusion film of the present invention, when viewed from above the film, the acute angle [theta] 2 formed by the extending direction of the plate-like region in the first louver structure and the longitudinal direction of the film is 10 to 80 And the acute angle? 3 formed by the extending direction of the plate-shaped area in the second louver structure and the longitudinal direction of the film is within a range of 10 to 80 degrees Value.

With this structure, the diffusion area of the incident light can be expanded more effectively.

In the construction of the light diffusion film of the present invention, when viewed from above the film, the extending direction of the plate-shaped area in the first louver structure and the extending direction of the plate- It is preferable that the imaginary line orthogonal to the longitudinal direction of the center line is line-symmetrical.

With this configuration, the incident light can be diffused more uniformly.

In the construction of the light-diffusing film of the present invention, it is preferable that the length of the light-diffusing film in the short direction is set to a value within a range of 0.1 to 3 m and the length in the long-side direction is set to a value of 3 m or more .

By such a constitution, it is possible to obtain an elongated phase and a large-area light diffusion film in which the diffusion area of the incident light is effectively widened.

Further, in constituting the light-diffusing film of the present invention, it is preferable that the light-diffusing film is rolled.

By such a constitution, it is possible to obtain an elongated phase light diffusion film with a wider effective area of the incident light and a larger light diffusion film.

In constructing the light diffusion film of the present invention, it is preferable that the thicknesses of the first louver structure and the second louver structure are each within a range of 50 to 500 mu m.

With this configuration, the diffusion area of the incident light can be expanded more effectively.

Further, in the construction of the light diffusion film of the present invention, it is preferable that the widths of the plate-shaped regions in the first louver structure and the second louver structure are each set within a range of 0.1 to 15 占 퐉.

With this configuration, the diffusion area of the incident light can be expanded more effectively.

Further, in the construction of the light diffusion film of the present invention, it is preferable that the raw material of the diffusion film is a composition for a light diffusion film containing two polymerizable compounds having different refractive indexes.

With this configuration, the diffusion area of the incident light can be further expanded more effectively.

1 (a) and 1 (b) are diagrams for explaining an outline of a louver structure in a light diffusion film.
2 (a) and 2 (b) are diagrams for explaining the incidence angle dependency, anisotropy and open angle in the light diffusion film.
Figs. 3 (a) to 3 (c) are provided for explaining the basic structure of the light diffusion film of the present invention. Fig.
4 (a) and 4 (b) are diagrams for explaining the louver structure.
5 (a) to 5 (c) are diagrams for explaining the extending direction of the plate-shaped area.
6 (a) and 6 (b) are diagrams for explaining the shape of a long-axis light diffusion film.
7 (a) to 7 (e) are diagrams for explaining the relationship between the extending direction of the plate-shaped area and the diffusion area of the incident light.
8 (a) to 8 (e) are photographs for explaining the relationship between the extending direction of the plate-shaped area and the diffusion area of the incident light.
Figs. 9 (a) to 9 (d) are diagrams for explaining respective steps in the method of manufacturing a light diffusion film of the present invention. Fig.
10 (a) and 10 (b) are diagrams for explaining active energy ray irradiation using a linear light source.
11 (a) and 11 (b) are diagrams for explaining the arrangement angles of the linear light sources.
Fig. 12 is another diagram for explaining active energy ray irradiation using a linear light source. Fig.
Fig. 13 is a view for explaining the configuration of the elongated light diffusing film of Example 1; Fig.
14 (a) to 14 (b) are photographs for explaining the shape of a section of a long-length light diffusing film of Example 1. Fig.
15 (a) and 15 (b) are diagrams for explaining the light diffusion characteristics of the long-axis light diffusion film of Example 1;
16 (a) to 16 (c) are diagrams for explaining the configuration of the first coating layer in which the first louver structure in Reference Example 1 is formed;
Fig. 17 is a view for explaining the configuration of the elongated-phase light-diffusing film of Reference Example 1. Fig.
18 (a) to 18 (b) are photographs for explaining the shape of a cross-section of a long-length light diffusing film of Reference Example 1. Fig.
19 (a) to 19 (b) are a spectrum diagram and a photograph provided for explaining light diffusion characteristics in a non-joint portion of a long-length light diffusion film of Reference Example 1. Fig.
20 (a) and 20 (b) are a spectrum diagram and a photograph provided for explaining light diffusion characteristics in a joint portion of a long-length light diffusion film of Reference Example 1. Fig.
Fig. 21 is a view for explaining the configuration of a long-lived light diffusion film of Comparative Example 1. Fig.
22 (a) and 22 (b) are photographs for explaining the shape of the cross-section of the elongated-phase light-diffusing film of Comparative Example 1. Fig.
23 (a) and 23 (b) are a spectrum diagram and a photograph provided to explain the light diffusion characteristics of the long-length light diffusion film of Comparative Example 1. Fig.
24 (a) and 24 (b) are provided for explaining a conventional light diffusion film.

An embodiment of the present invention is a long-lived light diffusion film having a first louver structure and a second louver structure sequentially from below in accordance with the film thickness direction, wherein the first louver structure and the second louver structure each have a refractive index And a plurality of plate-shaped regions having different refractive indexes are arranged alternately in an arbitrary one direction along the film plane, and when viewed from the upper side of the film, Wherein an acute angle (? 1) formed by the extending direction of the plate-shaped area in the structure and the extending direction of the plate-shaped area in the second louver structure is a value within a range of 10 to 90 degrees.

Hereinafter, embodiments of the present invention will be described concretely with reference to the drawings. In order to facilitate understanding of the description, first, the basic principle of light diffusion in a light diffusion film and the light diffusion film Will be described.

1. Basic principle of light diffusion in light diffusion film

First, the basic principle of light diffusion in a light diffusion film will be described with reference to Figs.

1 (a) shows a top view (top view) of the light diffusion film 10, and FIG. 1 (b) shows the light diffusion film 10 shown in FIG. Sectional view of the light diffusion film 10 when the cut surface is viewed in the direction of the arrow.

2 (a) shows the overall view of the light diffusion film 10 having a louver structure of one layer. Fig. 2 (b) shows the light diffusion film 10 of Fig. 2 And Fig.

As shown in the plan view of Fig. 1A, the light diffusion film 10 has a plate-shaped region 12 having a relatively high refractive index and a plate-shaped region 12 having a relatively low refractive index 14 are alternately arranged in parallel.

1 (b), the relatively high refractive index plate-shaped region 12 and the relatively low refractive index plate-like region 14 each have a predetermined thickness, and the light diffusion film 10 In the normal direction (film thickness direction) with respect to the direction of the film thickness.

As a result, as shown in Fig. 2 (a), when the incident angle is within the range of the light diffusion angle of incidence, it is assumed that the incident light is diffused by the light diffusion film 10.

That is, as shown in Fig. 1 (b), the angle of incidence of the incident light on the light diffusion film 10 is set to a value within a predetermined angle range from parallel to the interface 13 'of the louver structure 13, In the case of a value within the light diffusion angle of incidence, the incident light 52, 54 exits the inside of the relatively high refractive index plate-like region 12 in the louver structure along the film thickness direction while changing the direction, It is presumed that the traveling direction of light on the light-surface side becomes unlikely to be the same.

As a result, it is assumed that the incident light is diffused by the light diffusion film 10 (52 ', 54') when the incident angle is within the light diffusion incidence angle region.

On the other hand, when the incident angle of the incident light to the light diffusion film 10 deviates from the angle of the light diffusion angle of incidence, the incident light 56 is not diffused by the light diffusion film as shown in Fig. 1 (b) It is presumed to transmit the light diffusion film 10 as it is (56 ').

In the present invention, the " light diffusion angle of incidence angle range " means the angle range of the incident light corresponding to the diffusion of the diffused light when the angle of the incident light from the point light source is changed with respect to the light diffusion film .

Such a "light diffusion angle of incidence angle region" is an angle region determined for each light diffusion film by a difference in refractive index or an inclination angle of the louver structure in the light diffusion film as shown in FIG. 2 (a).

According to the basic principle described above, the light diffusion film 10 provided with the louver structure 13 can exhibit the incidence angle dependency in transmission and diffusion of light, for example, as shown in Fig. 2 (a) It becomes.

Also, as shown in Figs. 1 to 2, the light diffusion film having a single louver structure 13 usually has " anisotropy ".

Here, in the present invention, " anisotropy " means, as shown in Fig. 2 (a), in a case where incident light is diffused by a film, Means that the diffused state (the shape of the spread of the diffused light) has different properties depending on the direction in the hibernation.

More specifically, as shown in Fig. 2 (a), among the components included in the incident light, with respect to the component perpendicular to the direction of the louver structure extending along any one direction along the film plane, On the other hand, with respect to the component parallel to the direction of the louver structure included in the incident light, since it is difficult for light to diffuse, it is presumed that anisotropic light diffusion is realized.

Therefore, the spreading shape of the diffused light in the anisotropic light-diffusing film has a substantially elliptical shape as shown in Fig. 2 (a).

As described above, the component of the incident light contributing to the light diffusion is a component perpendicular to the direction of the louver structure extending along an arbitrary one direction mainly along the film plane. Therefore, as shown in Fig. 2 (b) In the present invention, the term "incident angle? 4" of the incident light means an incident angle of a component perpendicular to the direction of the louver structure extending along any one direction along the film plane. Incidentally, the incident angle? 4 here means the angle (°) when the angle of the incident-side surface of the light-diffusing film with respect to the normal is 0 °.

In the present invention, the "light diffusing angle region" means the angle range of diffused light obtained by fixing the point light source at an angle at which the incident light is most diffused with respect to the light diffusing film.

In the present invention, the "opening angle of diffused light" is the width of the above-described "light diffusing angle region", and as shown in Fig. 2 (b), a louver structure extending in any one direction along the film plane (? 5) of the diffused light when the cross section of the film is viewed from a direction X parallel to the direction of the film.

As shown in Fig. 2 (a), when the incident angle of the incident light is included in the light diffusion angle of incidence, the light diffusing film is able to diffuse substantially the same light on the light exiting surface side have.

Therefore, the obtained light diffusion film has a light converging action for focusing the light at a predetermined position.

The change in the direction of the incident light in the high refractive index region 12 in the louver structure is not limited to the case of the step index type in which the entire surface is changed to the zigzag shape by total internal reflection as shown in Fig. , A gradient index type that changes in a curve direction may be considered.

1 (a) and 1 (b), the interface between the plate-like region 12 having a relatively high refractive index and the region 14 having a relatively low refractive index is simply shown in a straight line. Actually, And each plateau region forms a complex refractive index distribution structure accompanied by branching and extinction.

As a result, it is presumed that the distribution of optical characteristics which are not the same improves the light diffusibility.

2. Basic Configuration

Next, the basic structure of the light-diffusing film of the present invention will be described with reference to Fig.

3 (c), the light diffusion film 20 of the present invention has the first louver structure 13a shown in FIG. 3 (a) and the second louver structure 13b ) In sequence from below in accordance with the film thickness direction.

The extending direction of the plateau region in the first louver structure 13a shown in Fig. 3 (a) and the extending direction of the plateau region in the second louver structure 13b shown in Fig. 3 (b) , And when they are viewed from the direction of the film, they cross each other.

Therefore, in the light diffusion film 20 of the present invention, the light incident on the film is first anisotropically light-diffused by the second louver structure 13b, for example, as shown in Fig. 3 (b) .

3 (a), the first louver structure 13a diffracts the anisotropically light-diffused diffused light by the second louver structure 13b in a direction different from the direction of the second louver structure 13b As shown in FIG.

As a result, as shown in Fig. 3 (c), light incident on the light diffusion film 20 of the present invention is light-diffused in a rectangular shape, and the diffusion area of the incident light can be effectively widened.

The above-mentioned " downward " means a side closer to the process sheet in the film thickness direction of the application layer when the application layer is provided on the process sheet. Therefore, it is a convenience term for explaining the present invention, and the vertical direction of the light diffusion film itself is not limited at all.

As shown in Fig. 3 (c), when the incident light is diffused by the film, the diffusion area of the incident light differs from that of the film at a predetermined distance from the film in the diffused outgoing light Quot; means the area in which the diffused light is distributed in the light source.

Hereinafter, the light diffusion film according to the present embodiment will be described in detail.

3. First Louver Structure

(1) Refractive index

In the first louver structure, it is preferable that the difference between the refractive indexes between the plate-shaped regions having different refractive indexes, that is, the difference between the refractive index of the plate-shaped region having a relatively high refractive index and the refractive index of the plate- Do.

This is because, by setting the difference in the refractive indexes to a value of 0.01 or more, incident light can be stably reflected in the first louver structure, and the dependency of the incidence angle derived from the first louver structure can be further improved.

More specifically, when the difference in the refractive index is less than 0.01, the angle of incidence of the incident light in the first louver structure becomes narrower, so that the incident angle dependency may be excessively lowered.

Therefore, it is more preferable that the difference in the refractive index between the plate-shaped regions having different refractive indexes in the first louver structure is 0.05 or more, more preferably 0.1 or more.

The larger the difference between the refractive index of the high refractive index plate-shaped region and the refractive index of the low refractive index plate-shaped region, the better, but from the viewpoint of selecting the material capable of forming the first louver structure, the upper limit is considered to be about 0.3.

Further, in the first louver structure, it is preferable that the refractive index of the plate-shaped region having a relatively high refractive index is set to a value within a range of 1.5 to 1.7.

This is because, when the refractive index of the high refractive index plate-shaped region is less than 1.5, the difference from the low refractive index plate-shaped region becomes too small, and it becomes difficult to obtain a desired louver structure. On the other hand, when the refractive index of the high refractive index plate-shaped region exceeds 1.7, compatibility between the material materials in the composition for a light diffusion film may be excessively lowered.

Therefore, the refractive index of the high refractive index plate-shaped region in the first louver structure is more preferably in the range of 1.52 to 1.65, and more preferably in the range of 1.55 to 1.6.

The refractive index of the high refractive index plate-shaped region can be measured, for example, in accordance with JIS K0062.

Further, in the first louver structure, it is preferable to set the refractive index of the plate-shaped region having a relatively low refractive index within a range of 1.4 to 1.5.

This is because if the refractive index of the low refractive index plate-shaped region is less than 1.4, the rigidity of the obtained light diffusion film may be lowered. On the other hand, when the refractive index of the low refractive index plate-like region exceeds 1.5, the difference from the refractive index of the high refractive index plate-like region becomes too small, and it becomes difficult to obtain a desired louver structure.

Therefore, the refractive index of the low refractive index plate-shaped region in the first louver structure is more preferably in the range of 1.42 to 1.48, and more preferably in the range of 1.44 to 1.46.

The refractive index in the low refractive index plate-shaped region can be measured in accordance with, for example, JIS K0062.

(2) Width

As shown in Fig. 4 (a), the widths S1 and S2 of the high refractive index plate-shaped region 12 and the low refractive index plate-shaped region 14, which have different refractive indexes, It is preferable to set the value within the range of 0.1 to 15 mu m.

The reason for this is that by making the width of the plate-shaped area within the range of 0.1 to 15 占 퐉, the incident light is more stably reflected in the first louver structure, This can be improved more effectively.

That is, when the width of such a plate-shaped area is less than 0.1 탆, it may be difficult to show the light diffusion irrespective of the incident angle of the incident light. On the other hand, when the width exceeds 15 mu m, the light advancing straight in the first louver structure increases and the uniformity of the diffused light may deteriorate.

Therefore, in the first louver structure, the widths of the plate-shaped regions having different refractive indexes are more preferably in the range of 0.5 to 10 mu m, and more preferably in the range of 1 to 5 mu m.

The width, length, and the like of the plate-like area constituting the first louver structure can be measured by observing the cross section of the film with an optical digital microscope.

(3) Inclination angle

4 (a), in the first louper structure, a plurality of high refractive index plate-shaped regions 12 and a plurality of low refractive index plate-shaped regions 14 having different refractive indexes are formed with constant It is preferable that they are arranged parallel to each other at an inclination angle [theta] a.

The reason for this is that it is possible to more reliably reflect the incident light in the first louver structure and to further improve the dependence of the incidence angle derived from the first louver structure by making each of the inclination angles? Because.

Further, &thetas; a is a plateau when the angle of the normal to the film surface measured on the cross section when the film is cut perpendicular to the first louver structure extending in any one direction along the film surface is 0 DEG Means the inclination angle (°) of the region.

More specifically, as shown in Fig. 4 (a), this means an angle between the normal of the upper end surface of the first louver structure and the uppermost portion of the plate-shaped area, which is the narrower side of the angle. As shown in Fig. 4 (a), the inclination angle when the plate-shaped area is inclined to the right is referred to as a reference, and the inclination angle when the plate-shaped area is inclined to the left is expressed as minus.

4 (b), it is also preferable that the plate-shaped regions 12 and 14 having different refractive indexes in the first louver structure are curved from above to below along the film thickness direction.

This is because the plateau region is curved so that the balance between reflection and transmission in the first louver structure is complicated and the opening angle of diffused light can be effectively expanded.

It is considered that such a curved louver structure is obtained by slowing the polymerization reaction speed by the ultraviolet rays in the thickness direction of the coating film.

Specifically, it is possible to suppress the illuminance of the ultraviolet light emitted from the linear light source and to move the coating film in the irradiated state at low speed.

(4) Thickness

In addition, the thickness of the first louver structure, that is, the length (L1) of the first louver structure existing portion in the normal direction of the film surface shown in Figs. 4A to 4B is within a range of 50 to 500 mu m .

The reason for this is that by making the thickness of the first louver structure a value within this range, the length of the first louver structure along the film thickness direction can be stably secured and the incident light can be stably reflected in the first louver structure , The uniformity of the intensity of the diffused light in the light diffusion angle region derived from the first louver structure can be further improved.

That is, when the thickness (L1) of the first louver structure is less than 50 mu m, the length of the first louver structure is insufficient, incident light which goes straight in the first louver structure increases, It is difficult to obtain the uniformity of the intensity of the diffused light in some cases. On the other hand, when the thickness (L1) of the first louver structure exceeds 500 mu m, when the first louver structure is formed by irradiating the active energy ray to the composition for the light diffusion film, The progress of the photopolymerization is diffused, and it is difficult to form the desired first louver structure.

Therefore, the thickness L1 of the first louver structure is more preferably in the range of 70 to 300 mu m, and more preferably in the range of 80 to 200 mu m.

(5) Extension direction

As shown in Fig. 5 (a), when viewed from above the film, the extending direction N1 of the plate-shaped regions 12 and 14 in the first louver structure 13a and the extending direction N1 of the film in the longitudinal direction E ') is set to a value within a range of 10 to 80 degrees.

The reason for this is that by making the extending direction of the plate-shaped area in the first louver structure a value within such a range, it is possible to prevent the incidence of the incident light in the direction along the long direction This is because the diffusion area of the incident light can be effectively widened by performing optical diffusion even in the direction orthogonal to the longitudinal direction.

That is, when the acute angle is less than 10, the light diffusing characteristic in the direction along the longitudinal direction of the film is excessively lowered, generally depending on the extending direction of the plate-shaped region in the second louver structure, The diffusion area of the diffusion layer may be excessively small. On the other hand, when the acute angle exceeds 80 DEG, the light diffusion characteristics in the direction orthogonal to the longitudinal direction of the film are excessively lowered, generally depending on the extending direction of the plateau region in the second louver structure , The diffusion area of the incident light may be excessively small.

Therefore, when viewed from above the film, the acute angle formed by the extending direction of the plate-like region in the first louver structure and the longitudinal direction of the film is more preferably in the range of 35 to 55 degrees, more preferably in the range of 40 to 50 Deg.], More preferably in the range of 44 to 46 [deg.].

4. Second Louver Structure

Since the configuration of the second louver structure is basically the same as that of the first louver structure, duplication is avoided and only the following points are described.

5 (b), when viewed from above the film, the extending direction N2 of the plate-shaped regions 12 and 14 in the second louver structure 13b and the extending direction N2 of the film in the longitudinal direction E ') is set to a value within a range of 10 to 80 degrees.

The reason for this is that by making the extending direction of the plate-shaped area in the second louver structure a value within this range, the incident light can be directed only in the direction along the long direction This is because the diffusion area of the incident light can be effectively widened by performing optical diffusion even in the direction orthogonal to the longitudinal direction.

Therefore, when viewed from above the film, the acute angle formed by the extending direction of the plate-like region in the second louver structure and the longitudinal direction of the film is more preferably in the range of 35 to 55 degrees, more preferably in the range of 40 to 50 Deg.], More preferably in the range of 44 to 46 [deg.].

5. Thickness

It is also preferable that the thickness of the light-diffusing film is within a range of 50 to 500 mu m.

This is because when the film thickness is less than 50 mu m, the length of the louver structure in the film thickness direction formed in the film is excessively shortened, so that the incident light which goes straight in the louver structure increases, It is difficult to obtain the angle dependency. On the other hand, when the film thickness exceeds 500 mu m, the irradiation light is irradiated for a long time, so that the mass productivity is excessively lowered, or the irradiation light is diffused by the louver structure formed at the beginning, Or it may be difficult to form a structure.

Therefore, the thickness of the light-diffusing film is more preferably in the range of 70 to 300 占 퐉, and more preferably in the range of 80 to 200 占 퐉.

In the film thickness direction of the light diffusion film, for example, there may be a portion where no louver structure exists in the surface layer portion.

Therefore, the film thickness of the light-diffusing film is equal to or more than the sum of the thickness of the first louver structure and the thickness of the second louver structure.

6. Shape of Film

Further, the shape of the light-diffusing film of the present invention is characterized by being a long shape.

More specifically, as shown in Fig. 6 (a), the length L2 of the light diffusion film 10 in the short side direction (width direction) is preferably set to a value within the range of 0.1 to 3 m, More preferably within a range of 1 to 2 m.

On the other hand, the length in the longitudinal direction is not particularly limited.

That is, the light diffusion film of the present invention can be continuously produced continuously by carrying out the production method as described later.

Therefore, the length L3 in the longitudinal direction is preferably set to a value of 3 m or more, more preferably 15 m or more.

The reason for this is that by making the film into such a shape, it is possible to provide a long-length image and a large-size light diffusion film capable of optically diffusing the incident light not only in the direction along the longitudinal direction thereof but also in the direction perpendicular to the longitudinal direction thereof I can get it.

Further, as shown in Fig. 6 (b), it is preferable that the light diffusion film 20 is rolled up.

The reason for this is that by forming the film in a rolled form, it is possible to obtain an elongated phase and a larger-area light diffusion film capable of optically diffusing incident light in a direction orthogonal to the longitudinal direction thereof or in the vicinity thereof.

Further, the handling properties during storage and transportation can be improved.

That is, even if the size of the display or the like to which the film is to be applied is varied, it can be chipped at a required size later if it is roll-shaped.

Further, in the case of rolls, the rolls can be joined to other rolls and rolls in the next step, and the productivity can be improved as compared with the case where a sheet-to-sheet is employed.

7. Combination of extension direction

In the light diffusion film of the present invention, as viewed from above the film, as shown in Fig. 5 (c), the extending direction of the plate-shaped regions 12 and 14 in the first louver structure 13a 1 formed by the first louver structure 13 and the extending direction N2 of the plate-shaped regions 12, 14 in the second louver structure 13b is set to a value within a range of 10 to 90 degrees.

The reason for this is that it is possible to obtain an elongated film in which the diffusion area of the incident light is effectively widened by optically diffusing the incident light not only in the direction along the longitudinal direction but also in the direction orthogonal to the longitudinal direction Because.

That is, when the acute angle is less than 10, the diffusion area of the incident light may be excessively small.

Therefore, when viewed from above the film, the acute angle formed by the extending direction of the plate-shaped area in the first louver structure and the extending direction of the plate-shaped area in the second louver structure is set to a value within a range of 80 to 90 degrees More preferably a value within a range of 85 to 90 DEG, and still more preferably a value within a range of 89 to 90 DEG.

5 (c), when viewed from above the film, the extending direction N1 of the plate-shaped regions 12 and 14 in the first louver structure 13a is different from the extending direction N1 in the second louver structure 13a It is preferable that the extending direction N2 of the plate-like regions 12 and 14 in the first and second plate portions 13a and 13b is a line-symmetrical with respect to a virtual line E 'perpendicular to the longitudinal direction E' of the film.

This is because the incident light can be more uniformly diffused by uniformly crossing the extending direction of the plateau region in the first louver structure and the extending direction of the plateau region in the second louver structure .

Specifically, in the case of θ2 = 45 ° and θ3 = 45 °, or in the case where each is a peripheral value, the extending direction of the plateau region in each louver structure is made to be a line symmetry, The spreading in the left-right direction and the spreading in the up-down direction in the diffused light can be respectively maximized.

Therefore, when such a light diffusion film is applied to a screen, the lateral viewing angle and the longitudinal viewing angle can be respectively maximized.

Here, the relationship between the extending direction of the plate-shaped area and the diffusion area of the incident light will be described with reference to Figs. 7 (a) to 7 (e).

7A to 7E show the first louver structure 13a and the light diffusion state 50 'incident on the first louver structure 13a on the left side and the second louver structure 13b and the second louver structure 13b on the right side, And shows the diffusion state 51 'of the diffusion light by the incident first louver structure 13a.

7A shows the diffused state of incident light in the case of? 1 = 90 deg.,? 2 = 45 deg., And? 3 = 45 deg. However, it can be seen that the final diffused area of the incident light is sufficiently widened (51 ').

On the other hand, Fig. 7 (b) shows the diffused state of the incident light in the case of? 1 = 60,? 2 = 30, and? 3 = 30, It is understood that the light diffusion characteristic in the direction along the direction E 'is lowered and the diffusion area of the incident light is reduced (51').

7 (c) shows the diffused state of incident light in the case of? 1 = 60,? 2 = 60, and? 3 = 60. Compared with the case of FIG. 7 (a) It is understood that the light diffusion characteristic in the direction orthogonal to the direction E 'is lowered and the diffusion area of the incident light becomes smaller (51').

On the other hand, Fig. 7 (d) shows the diffused state of incident light in the case of? 1 = 30,? 2 = 15, and? 3 = 15. Compared with the case of Fig. The light diffusion characteristic in the direction along the direction E 'is further lowered, and the diffusion area of the incident light becomes smaller (51').

7 (e) shows the diffused state of incident light in the case of? 1 = 30,? 2 = 75, and? 3 = 75. Compared with the case of FIG. 7 (a) It is understood that the light diffusion characteristic in the direction orthogonal to the direction E 'is further lowered, and the diffusion area of the incident light becomes smaller (51').

Figs. 8 (a) to 8 (e) show photographs of diffused light corresponding to Figs. 7 (a) to 7 (e).

8. Pressure-sensitive adhesive layer

The light diffusion film obtained by the production method of the present invention may have a pressure-sensitive adhesive layer for laminating the adherend on one side or both sides thereof.

The pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer is not particularly limited, and conventionally known pressure-sensitive adhesives such as acryl, silicone, urethane, rubber can be used.

9. Manufacturing Method

Further, the light-diffusing film of the present invention can be produced, for example, by a manufacturing method including the following steps (a) to (e).

(a) preparing a composition for a light-diffusing film containing two polymerizable compounds having different refractive indexes

(b) a step of applying a composition for a light diffusion film to a process sheet to form a first coated layer

(c) a step of forming a first louver structure by irradiating the first coated layer with a first active energy ray irradiation using a linear light source while moving the first coated layer;

(d) applying a composition for a light-diffusing film to the first coating layer having the first louver structure to form a laminate composed of the first coating layer and the second coating layer

(e) a step of forming a second louver structure by performing a second activation energy ray irradiation with a linear light source while moving a laminate composed of the first coating layer and the second coating layer with respect to the second coating layer , When viewed from above the film, an acute angle (? 1 ') between the major axis direction of the linear light source in the first active energy ray irradiation and the major axis direction of the linear light source in the second active energy ray irradiation is 10 to 90 Lt; RTI ID = 0.0 >

Hereinafter, this manufacturing method will be described in detail with reference to the drawings.

(1) Step (a): Preparation of composition for light diffusion film

The step (a) is a step of preparing a predetermined composition for a light diffusion film.

More specifically, the step is preferably a step of mixing at least two polymerizable compounds having different refractive indexes, a photopolymerization initiator, and other additives by desirability.

In the mixing, the mixture may be stirred as it is at room temperature. However, from the viewpoint of improving the uniformity, the mixture is preferably stirred at a temperature of 40 to 80 캜 under a warming condition.

It is also preferable to further add a diluting solvent so as to have a desired viscosity suitable for coating.

Hereinafter, the step (a) will be described in more detail.

(1) -1 High refractive index polymerizable compound

(i) Type

The kind of the polymerizable compound having a relatively high refractive index (hereinafter may be referred to as the component (A)) among the two polymerizable compounds having different refractive indexes is not particularly limited, but the main component thereof may be a compound containing a plurality of aromatic rings (Meth) acrylic acid ester.

The reason for this is that the polymerization rate of the component (A) is lowered by incorporating a specific (meth) acrylic acid ester as the component (A) into the polymerizable compound having a relatively low refractive index (hereinafter referred to as component (B) ), And it is presumed that the polymerization rate of these components can be made to be a predetermined difference to effectively lower the copolymerization of both components.

As a result, it is possible to efficiently form a so-called louver structure in which plate-shaped regions derived from the component (A) and plate-shaped regions derived from the component (B) alternately extend when light cured.

Further, by containing the specific (meth) acrylic acid ester as the component (A), the component (B) is sufficiently compatible with the component (B) Is lowered to a predetermined range, so that the louver structure can be formed more efficiently.

Further, by containing the specific (meth) acrylic acid ester as the component (A), the refractive index of the plate-like region derived from the component (A) in the louver structure is increased and the refractive index of the plate- Can be adjusted to a predetermined value or more.

Therefore, by containing the specific (meth) acrylic acid ester as the component (A), it is possible to efficiently obtain the louver structure in which plate-shaped regions having different refractive indexes are alternately extended in addition to the properties of the component (B) .

The term "(meth) acrylic acid ester containing a plurality of aromatic rings" means a compound having a plurality of aromatic rings in the ester residue portion of the (meth) acrylic acid ester.

The term "(meth) acrylic acid" means both of acrylic acid and methacrylic acid.

Examples of the (meth) acrylic acid ester containing a plurality of aromatic rings as the component (A) include biphenyl (meth) acrylate, naphthyl (meth) acrylate, anthracyl (meth) acrylate, (Meth) acrylate, benzylphenyloxyalkyl (meth) acrylate, naphthyloxyalkyl (meth) acrylate, anthracyloxyalkyl (meth) acrylate and benzylphenyloxyalkyl Is substituted with halogen, alkyl, alkoxy, halogenated alkyl, or the like.

The (meth) acrylic acid ester containing a plurality of aromatic rings as the component (A) preferably contains a compound containing a biphenyl ring. In particular, a biphenyl compound represented by the following general formula (1) .

(Formula (1) of, R ¹ ~R ¹⁰ are, respectively and independently, at least one of R ¹ ~R ¹⁰ is, to a substituent group represented by formula (2), and the other is a hydrogen atom, a hydroxyl group , A carboxy group, an alkyl group, an alkoxy group, a halogenated alkyl group, a hydroxyalkyl group, a carboxyalkyl group and a halogen atom)

(In the general formula (2), R ¹¹ is a hydrogen atom or a methyl group, the number of carbon atoms is an integer of 1 to 4, and the number of repeating m is an integer of 1 to 10)

This is because a predetermined difference in polymerization rate between the component (A) and the component (B) is generated by containing a biphenyl compound having a specific structure as the component (A) It is presumed that the compatibility of the component (B) can be lowered to a predetermined range so as to lower the copolymerization of the two components.

Further, the refractive index of the plate-like region derived from the component (A) in the louver structure can be increased, and the difference between the refractive index of the plate-shaped region derived from the component (B) and the refractive index of the plate-

When R ¹ to R ¹⁰ in the general formula (1) contain any one of an alkyl group, an alkoxy group, a halogenated alkyl group, a hydroxyalkyl group, and a carboxyalkyl group, the alkyl moiety of the alkyl moiety may have 1 to 4 Is preferably within a range of "

This is because when the number of carbon atoms exceeds 4, the polymerization rate of the component (A) decreases and the refractive index of the plate-like region derived from the component (A) becomes too low to efficiently form a louver structure It may be difficult to do so.

Therefore, when R ¹ to R ¹⁰ in the general formula (1) contain any one of an alkyl group, an alkoxy group, a halogenated alkyl group, a hydroxyalkyl group, and a carboxyalkyl group, More preferably within a range of 1 to 2, and still more preferably, within a range of 1 to 2.

In addition, it is preferable that R ¹ to R ¹⁰ in the general formula (1) are a halogenated alkyl group or a substituent other than a halogen atom, that is, a halogen-free substituent.

This is because dioxin is prevented from occurring when the light diffusion film is incinerated or the like, which is preferable from the viewpoint of environmental protection.

In addition, in a conventional light diffusion film having a louver structure, in order to obtain a predetermined louver structure, halogen substitution has generally been performed on the monomer component for the purpose of making the monomer component high in refractive index.

From this point of view, the biphenyl compound represented by the general formula (1) can have a high refractive index even when halogen substitution is not performed.

Therefore, the light diffusion film obtained by photo-curing the composition for a light diffusion film in the present invention can exhibit a good incident angle dependency even when it does not contain a halogen.

The "good incident angle dependency" means that the distinction between the light diffusion incidence angle region and the non-scattering incident angle region which is transmitted without being diffused incident light is clearly controlled.

It is preferable that any one of R ² to R ⁹ in the general formula (1) is a substituent represented by the general formula (2).

This is because the position of the substituent represented by the general formula (2) is set to a position other than R ¹ and R ¹⁰ so that the components (A) are oriented and crystallized in the step before the photo-curing This is because it can be effectively prevented.

In addition, it can be uniformly mixed with the component (B) in appearance even when a diluting solvent or the like is not used at the monomer stage before photo-curing.

This makes it possible to aggregate and phase-separate the component (A) and the component (B) at a fine level at the stage of photo-curing and to obtain a light diffusion film having a louver structure more efficiently to be.

From the same viewpoint, it is particularly preferable that any one of R ³ , R ⁵ , R ⁶ and R ⁸ in the general formula (1) is a substituent represented by the general formula (2).

The repeating number m in the substituent represented by the general formula (2) is preferably an integer of usually 1 to 10.

This is because, when the number of repeating m exceeds 10, the polymerization site and the oxyalkylene chain connecting the biphenyl ring become too long to inhibit the polymerization of the component (A) in the polymerization site There is.

Therefore, the number of repeating m in the substituent represented by the general formula (2) is more preferably an integer of 1 to 4, particularly preferably an integer of 1 to 2.

From the same viewpoint, the number n of carbon atoms in the substituent represented by the general formula (2) is preferably an integer of usually 1 to 4.

Considering also the case where the position of the polymerizable carbon-carbon double bond as the polymerization site is too close to the biphenyl ring, the biphenyl ring becomes steric hindrance, and the polymerization rate of the component (A) decreases, 2) is more preferably an integer of 2 to 4, and particularly preferably an integer of 2 to 3.

Specific examples of the biphenyl compound represented by the general formula (1) include compounds represented by the following general formulas (3) to (4).

(Ii) Molecular weight

The molecular weight of the component (A) is preferably in the range of 200 to 2,500.

This is because the molecular weight of the component (A) is set to a predetermined range, so that the polymerization rate of the component (A) is made faster and the copolymerization of the components (A) and (B) .

As a result, when the photo-curing is performed, a louver structure in which a plate-like region derived from the component (A) and a plate-like region derived from the component (B) are alternately extended can be formed more efficiently.

That is, when the molecular weight of the component (A) is less than 200, the polymerization rate is lowered due to steric hindrance, so that the polymerization rate of the component (B) becomes close to that of the component (B) Because. On the other hand, when the molecular weight of the component (A) exceeds 2,500, the difference in molecular weight from the component (B) decreases, the polymerization rate of the component (A) decreases and the polymerization rate of the component And it is presumed that copolymerization with the component (B) tends to occur easily. As a result, it may be difficult to form the louver structure efficiently.

Therefore, the molecular weight of the component (A) is more preferably in the range of 240 to 1,500, and more preferably in the range of 260 to 1,000.

The molecular weight of the component (A) can be determined from the composition of the molecule and the calculated value obtained from the atomic weight of the constituent atom, and can be measured as the weight average molecular weight using gel permeation chromatography (GPC).

(Iii) Single use

Further, the composition for a light-diffusing film in the present invention is characterized by containing a component (A) as a monomer component forming a plate-shaped region having a relatively high refractive index in a louver structure, and the component (A) It is preferably contained as one component.

This is because the light diffusion film having the louver structure can be effectively prevented by suppressing unevenness of the refractive index in the plate-like region derived from the component (A), that is, the plate-shaped region having a relatively high refractive index, It can be obtained more efficiently.

That is, when the compatibility of the component (A) with the component (B) is low, for example, when the component (A) is a halogen-based compound or the like, As the third component, another component (A) (for example, a non-halogen compound or the like) may be used in combination.

However, in this case, due to the influence of the third component, the refractive index in the plate-shaped region derived from the component (A) is relatively high, or the refractive index may become uneven.

As a result, there may be a case where the difference in refractive index between the component (B) and the plate-like region having a relatively low refractive index becomes uneven or is likely to excessively decrease.

Therefore, it is preferable to select a monomer component having a high refractive index that is compatible with the component (B) and use it as the component (A) alone.

Further, for example, the biphenyl compound represented by the formula (3) as the component (A) has low viscosity and can be used as the component (A) alone because of its compatibility with the component (B).

(Iv) refractive index

The refractive index of the component (A) is preferably set to a value within a range of 1.5 to 1.65.

This is because the difference between the refractive index of the plate-like region derived from the component (A) and the refractive index of the plate-shaped region derived from the component (B) This is because the light diffusion film having the louver structure can be obtained more efficiently by easily adjusting it.

That is, when the refractive index of the component (A) is less than 1.5, the difference between the refractive index of the component (B) and the refractive index of the component (B) becomes too small and it becomes difficult to obtain an effective light diffusion angle region. On the other hand, when the refractive index of the component (A) exceeds 1.65, the difference from the refractive index of the component (B) becomes large, but it may be difficult to form even the apparent compatibility with the component (B).

Therefore, the refractive index of the component (A) is more preferably in the range of 1.52 to 1.65, and more preferably in the range of 1.56 to 1.6.

The refractive index of the above-mentioned component (A) means the refractive index of the component (A) before curing by light irradiation.

The refractive index can be measured in accordance with, for example, JIS K0062.

(v) Content

The content of the component (A) in the composition for a light-diffusing film is set to a value within a range of 25 to 400 parts by weight with respect to 100 parts by weight of the component (B) which is a polymerizable compound having a relatively low refractive index, .

This is because when the content of the component (A) is less than 25 parts by weight, the presence of the component (A) in the component (B) decreases and the width of the plate- Is too small in comparison with the width of the plate-like region derived from the component (B), and it may be difficult to obtain a louver structure having a good incident angle dependency. Further, the length of the louver in the thickness direction of the light-diffusing film becomes insufficient, and light diffusibility may not be exhibited. On the other hand, when the content of the component (A) exceeds 400 parts by weight, the proportion of the component (A) to the component (B) increases and the width of the plate- ) Component, and conversely, it may be difficult to obtain a louver structure having a good incident angle dependency. Further, the length of the louver in the thickness direction of the light-diffusing film becomes insufficient, and light diffusibility may not be exhibited.

Therefore, the content of the component (A) is more preferably within a range of 40 to 300 parts by weight, and more preferably within a range of 50 to 200 parts by weight, with respect to 100 parts by weight of the component (B).

(1) -2 Low refractive index polymerizable compound

(i) Type

Of the two polymerizable compounds having different refractive indexes, the kind of the polymerizable compound (component (B)) having a relatively low refractive index is not particularly limited, and examples of the main component thereof include urethane (meth) acrylate, (Meth) acryloyl group-containing (meth) acryloyl group, a (meth) acryloyl group-containing silicone resin and an unsaturated polyester resin. Of these, urethane (meth) acrylate is particularly preferable.

This is because not only the difference between the refractive index of the plate-like region derived from the component (A) and the refractive index of the plate-shaped region derived from the component (B) can be more easily controlled by urethane (meth) The irregularity of the refractive index of the plate-like region derived from the component (B) can be effectively suppressed, and a light diffusion film having a louver structure can be obtained more efficiently.

Therefore, hereinafter, the urethane (meth) acrylate as the component (B) will be mainly described.

Further, (meth) acrylate means both of acrylate and methacrylate.

(B1) a compound containing at least two isocyanato groups, (B2) a polyol compound, preferably a diol compound, particularly preferably a polyalkylene glycol, and (B3) a polyol compound, Hydroxyalkyl (meth) acrylate.

The component (B) also includes an oligomer having repeating units of a urethane bond.

Among them, examples of the compound containing at least two isocyanato groups as the component (B1) include 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 1,3-xylylene diisocyanate, Alicyclic polyisocyanates such as hexamethylene diisocyanate, alicyclic polyisocyanates such as isophorone diisocyanate (IPDI) and hydrogenated diphenylmethane diisocyanate, and aromatic polyisocyanates such as buret (For example, a xylylene diisocyanate-based compound such as a xylylene diisocyanate-based compound 3, which is a reaction product of an isocyanurate compound, an isocyanurate compound, and an isocyanurate compound and a low molecular active hydrogen- containing compound such as ethylene glycol, propylene glycol, neopentyl glycol, trimethylolpropane, Functional adducts) and the like.

Among the above, alicyclic polyisocyanates are particularly preferable.

This is because, in the case of the alicyclic polyisocyanate, the difference in the reaction rates of the respective isocyanato groups is easier to obtain in comparison with the aliphatic polyisocyanate due to steric hindrance.

This prevents the component (B1) from reacting only with the component (B2) or from reacting only the component (B1) with the component (B3) Component can be surely reacted with the component, and the occurrence of excessive by-products can be prevented.

As a result, it is possible to effectively suppress the irregularity of the refractive index of the plate-like region derived from the component (B) in the louver structure, that is, the low-refractive-index plate-shaped region.

In addition, when the alicyclic polyisocyanate is used, the compatibility of the resulting component (B) with the component (A) is lowered to a predetermined range as compared with the aromatic polyisocyanate, so that the louver structure can be formed more efficiently.

Further, in the case of the alicyclic polyisocyanate, since the refractive index of the obtained component (B) can be made smaller than that of the aromatic polyisocyanate, the difference from the refractive index of the component (A) is increased to manifest the light diffusion property more reliably The louver structure having high uniformity of the diffused light within the light diffusion angle region can be formed more efficiently.

Among these alicyclic polyisocyanates, alicyclic diisocyanates containing only two isocyanato groups are preferable.

This is because, when alicyclic diisocyanate is used, it is possible to quantitatively react with the component (B2) and the component (B3) to obtain a single component (B).

As the alicyclic diisocyanate, isophorone diisocyanate (IPDI) is particularly preferred.

This is because it is possible to provide a difference in the reactivity of the two isocyanato groups.

Among the components forming the urethane (meth) acrylate, examples of the polyalkylene glycol as the component (B2) include polyethylene glycol, polypropylene glycol, polybutylene glycol, polyhexylene glycol and the like Among these, polypropylene glycol is particularly preferable.

This is because if the polypropylene glycol is low in viscosity, it can be treated as a solvent.

Further, when polypropylene glycol is used as the component (B), it is a good soft segment in the cured product when the component (B) is cured, and the handling and mounting properties of the light diffusion film can be effectively improved.

The weight average molecular weight of the component (B) can be controlled mainly by the weight average molecular weight of the component (B2). Here, the weight average molecular weight of the component (B2) is usually from 2,300 to 19,500, preferably from 4,300 to 14,300, and particularly preferably from 6,300 to 12,300.

Among the components forming urethane (meth) acrylate, examples of the hydroxyalkyl (meth) acrylate which is the component (B3) include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl Hydroxybutyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 3-hydroxybutyl .

From the viewpoint of lowering the polymerization rate of the urethane (meth) acrylate to be obtained and forming a predetermined louver structure more efficiently, it is more preferable to use hydroxyalkyl methacrylate, more preferably 2-hydroxyethyl methacrylate Rate is more preferable.

The synthesis of the urethane (meth) acrylate by the components (B1) to (B3) can be carried out by a conventional method.

At this time, it is preferable that the mixing ratio of the components (B1) to (B3) is in the ratio of (B1) component: (B2) component: (B3) component = 1: 5: 1:

The reason for this is that by using this compounding ratio, one isocyanato group of the component (B1) reacts and bonds to two hydroxyl groups of the component (B2), and two (B1) (Meth) acrylate in which the hydroxyl group of the component (B3) reacts and bind to another isocyanato group which is bonded to the other isocyanato group.

Therefore, it is more preferable that the blending ratio of the components (B1) to (B3) is in the ratio of the component (B1) :( B2) :( B3) = 1: 3: 1: 2: 1: 2.

(Ii) weight average molecular weight

The weight average molecular weight of the component (B) is preferably in the range of 3,000 to 20,000.

This is because, by setting the weight average molecular weight of the component (B) to a predetermined range, a predetermined difference in polymerization rate between the component (A) and the component (B) is generated to effectively lower the copolymerization of the two components It is because.

As a result, when the photo-curing is performed, a louver structure in which plate-shaped regions derived from the component (A) and plate-shaped regions derived from the component (B) are alternately extended can be efficiently formed.

That is, when the weight average molecular weight of the component (B) is less than 3,000, the polymerization rate of the component (B) becomes faster, the polymerization rate of the component (A) becomes closer to that of the component (A) , It may be difficult to form the louver structure efficiently. On the other hand, when the weight average molecular weight of the component (B) exceeds 20,000, it becomes difficult to form a louver structure in which plate-like regions derived from the components (A) and (B) ) Component is excessively lowered, so that the component (A) may precipitate in the coating step.

Therefore, the weight average molecular weight of the component (B) is more preferably in the range of 5,000 to 15,000, and more preferably in the range of 7,000 to 13,000.

The weight average molecular weight of the component (B) can be measured by gel permeation chromatography (GPC).

(Iii) Single use

The component (B) may be used in combination of two or more species having different molecular structures or different weight average molecular weights. From the viewpoint of suppressing unevenness of the refractive index of the plate-like region derived from the component (B) in the louver structure, Is preferably used.

That is, when a plurality of the component (B) is used, the refractive index in the plate-like region derived from the component (B) is relatively low or becomes high and the refractive index derived from the component (A) The refractive index difference with respect to the high plate-shaped area may become uneven or excessively decrease.

(Iv) refractive index

Further, it is preferable to set the refractive index of the component (B) within the range of 1.4 to 1.55.

The reason for this is that by making the refractive index of the component (B) fall within this range, the difference between the refractive index of the plate-shaped region derived from the component (A) and the refractive index of the plate-shaped region derived from the component (B) The light diffusion film having the louver structure can be obtained more efficiently.

That is, when the refractive index of the component (B) is less than 1.4, the difference from the refractive index of the component (A) increases, but the compatibility with the component (A) is extremely deteriorated, There is. On the other hand, when the refractive index of the component (B) exceeds 1.55, the difference between the refractive index of the component (A) and the refractive index of the component (B) becomes too small, and it becomes difficult to obtain a desired incident angle dependency.

Therefore, the refractive index of the component (B) is more preferably in the range of 1.45 to 1.54, and more preferably in the range of 1.46 to 1.52.

The refractive index of the above-mentioned component (B) means the refractive index of the component (B) before curing by light irradiation.

The refractive index can be measured in accordance with, for example, JIS K0062.

The difference between the refractive index of the component (A) and the refractive index of the component (B) is preferably 0.01 or more.

The reason for this is that by setting the difference in the refractive index within a predetermined range, it is possible to obtain a light diffusion film having a better incident angle dependency in light transmission and diffusion and a wider light diffusion angle of incidence angle region to be.

That is, when the difference in the refractive index is less than 0.01, the angle of incidence of the incident light in the louver structure is narrowed, so that the angle of opening in the light diffusion may be excessively narrowed. On the other hand, if the difference in the refractive index becomes excessively large, the compatibility of the component (A) and the component (B) becomes excessively worse, and there is a possibility that the louver structure can not be formed.

Therefore, the difference between the refractive index of the component (A) and the refractive index of the component (B) is more preferably within a range of 0.05 to 0.5, and more preferably within a range of 0.1 to 0.2.

The refractive index of the component (A) and the component (B) referred to herein means the refractive index of the component (A) and the component (B) before curing by light irradiation.

(v) Content

The content of the component (B) in the composition for a light-diffusing film is preferably within a range of 10 to 80% by weight based on 100% by weight of the total amount of the composition for a light-diffusing film.

This is because when the content of the component (B) is less than 10% by weight, the proportion of the component (B) to the component (A) decreases and the width of the plate- It is excessively small in comparison with the width of the plate-like region derived from the component (A), and it may be difficult to obtain a louver structure having a good incident angle dependency. This is because the length of the louver in the thickness direction of the light diffusion film may become insufficient. On the other hand, when the content of the component (B) exceeds 80% by weight, the presence of the component (B) in the component (A) increases and the width of the plate- It is difficult to obtain a louver structure which is excessively large in comparison with the width of the plate-like region derived from the component (A) and conversely has a good incident angle dependency. This is because the length of the louver in the thickness direction of the light diffusion film may become insufficient.

Therefore, the content of the component (B) is more preferably in the range of 20 to 70% by weight, more preferably in the range of 30 to 60% by weight based on 100% by weight of the total amount of the composition for the light- .

(1) -3 Photopolymerization initiator

In the composition for a light-diffusing film in the present invention, it is preferable that a photopolymerization initiator is contained as the component (C), if desired.

This is because, when the composition for a light diffusion film is irradiated with active energy rays, a louver structure can be efficiently formed by incorporating a photopolymerization initiator.

Here, the photopolymerization initiator refers to a compound that generates radical species by irradiation with active energy rays such as ultraviolet rays.

Examples of such photopolymerization initiators include benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin-n-butyl ether, benzoin isobutyl ether, acetophenone, dimethylaminoacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxy-2-phenylacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-hydroxycyclohexyl 2-methyl-1- [4- (methylthio) phenyl] -2-morpholino-propan-1-one, 4- (2-hydroxyethoxy) -Propyl ketone, benzophenone, p-phenylbenzophenone, 4,4-diethylaminobenzophenone, dichlorobenzophenone, 2-methyl anthraquinone, 2- ethyl anthraquinone, 2- Aminothraquinone, 2-methylthioxanthone, 2-ethylthioxanthone, 2-chlorothioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, benzyldimethylketal, acetophenone dimethylketal, Dimethylamine benzoate Propyl], and one of these may be used singly or in combination of two or more kinds thereof. The term " 2-hydroxy-2-methyl- .

When the photopolymerization initiator is contained, the content of the photopolymerization initiator is preferably in the range of 0.2 to 20 parts by weight, more preferably in the range of 0.5 to 15 parts by weight per 100 parts by weight of the total of the components (A) and (B) , More preferably in a range of 1 to 10 parts by weight.

(1) -4 Other additives

In addition, additives other than the above-mentioned compounds may be added to the extent that the effect of the present invention is not impaired.

Examples of such additives include antioxidants, ultraviolet absorbers, antistatic agents, polymerization accelerators, polymerization inhibitors, infrared absorbers, plasticizers, diluting solvents, leveling agents and the like.

In general, the content of such an additive is preferably within a range of 0.01 to 5 parts by weight, more preferably within a range of 0.02 to 3 parts by weight, based on 100 parts by weight of the total amount of the components (A) and (B) , More preferably 0.05 to 2 parts by weight.

(2) Step (b): First coating step

The step (b) is a step of forming the first coated layer 1a by applying the prepared composition for light diffusion film to the process sheet 2 as shown in Fig. 9 (a).

As the process sheet, a plastic film or paper can be used.

Examples of the plastic film include a polyester film such as a polyethylene terephthalate film, a polyolefin film such as a polyethylene film and a polypropylene film, a cellulose film such as a triacetyl cellulose film, a polyimide film, and the like .

Examples of the paper include a gloss paper, a coated paper, a laminated paper, and the like.

In consideration of the process described later, the process sheet (2) is preferably a plastic film excellent in dimensional stability against heat or active energy rays.

Among these plastic films, polyester films, polyolefin films and polyimide films are preferable.

For the process sheet, it is preferable to provide a release layer on the application side of the light diffusion film composition in the process sheet in order to easily peel off the obtained light diffusion film from the process sheet after photo-curing.

Such a release layer can be formed by using a conventionally known release agent such as a silicone-based release agent, a fluorine-based release agent, an alkyd-based release agent, and an olefin-based release agent.

The thickness of the process sheet is preferably set within a range of usually 25 to 200 mu m.

Examples of the method of applying the composition for a light diffusion film on the process sheet include a known method such as a knife coating method, a roll coating method, a bar coating method, a blade coating method, a die coating method, and a gravure coating method Method can be used.

It is also preferable that the film thickness of the first coating layer is within a range of 80 to 700 mu m.

This is because the first louver structure can be formed more efficiently by setting the film thickness of the first coating layer to a value within this range.

That is, when the film thickness of the first coating layer is less than 80 占 퐉, the length of the first louver structure to be formed is insufficient, incident light which goes straight in the first louver structure increases, It is difficult to obtain the uniformity of the intensity of the diffused light. On the other hand, when the film thickness of the first coating layer exceeds 700 mu m, when the first coating layer is irradiated with the active energy ray to form the first louver structure, the light- The direction is diffused, and it may be difficult to form a desired louver structure.

Therefore, it is more preferable to set the film thickness of the first coating layer within the range of 100 to 500 mu m, more preferably to be within the range of 120 to 300 mu m.

(3) Step (c): First active energy ray irradiation step

9 (b), in the step (c), while the first coated layer 1a is moved in the moving direction E, the linearly polarized light is transmitted to the linearly polarized light source 125a, Is used to conduct the first activation energy ray irradiation 150a to form the first louver structure 13a.

More specifically, for example, as shown in Fig. 10 (a), an ultraviolet irradiating apparatus 120 (for example, a commercially available ultraviolet irradiating apparatus) having a cold mirror 122 for light- The heat ray cut filter 121 and the light shielding plates 123 (123a and 123b) are arranged on the active energy ray 150a (made by IGraphics Co., Ltd., ECS-4011GX etc.) And the first coated layer 1a formed on the process sheet 2 is irradiated.

As shown in Fig. 11 (a), when viewed from above the film, the long axis direction of the linear light source 125a in the first active energy ray irradiation and the moving direction of the first coated layer 1a 2 ') formed by the imaginary line E' (the longitudinal direction of the film) according to the angle? E is preferably within the range of 10 to 80 degrees.

The reason for this is that by defining the arrangement angle of the linear light sources in this way, the incident angle of the incident light in the step (e) to be described later can be adjusted not only by the direction along the long direction, It is possible to manufacture a long-length light diffusion film effectively widening the diffusion area of incident light more efficiently.

That is, when the angle θ2 'is less than 10 °, the light diffusing property in the direction along the longitudinal direction of the film is excessively lowered, generally depending on the arrangement angle of the linear light source in the step (e) This is because the diffusion area of the incident light may be excessively small. On the other hand, when the angle θ2 'exceeds a value of 80 °, the light diffusing characteristics in the direction orthogonal to the longitudinal direction of the film generally vary depending on the arrangement angle of the linear light sources in the step (e) , And the diffusion area of the incident light may be excessively small.

Therefore, when viewed from above the film, the acute angle? 2 'formed by the imaginary line along the major axis direction of the linear light source in the first active energy ray irradiation and the moving direction of the first coated layer is set to 35 to 55 degrees More preferably within the range of 40 to 50 degrees, and still more preferably within the range of 44 to 46 degrees.

It is preferable that the gap between the linear light sources 125a and the coating layer 1a is substantially the same at any position.

10 (b), the irradiation angle? 6 when the angle of the normal to the surface of the first coated layer 1a is 0 is set to be -80 To < RTI ID = 0.0 > 80. ≪ / RTI >

The reason for this is that if the irradiation angle is outside the range of -80 to 80 degrees, the influence of reflection or the like on the surface of the first coated layer 1a becomes large and it becomes difficult to form a sufficient louver structure Because.

Further, the irradiation angle 6 preferably has a width (irradiation angle width) 6 'of 1 to 80 degrees.

This is because, if the irradiation angle width 6 'is less than 1 DEG, the moving speed of the coating layer must be excessively lowered, and the manufacturing efficiency may be lowered. On the other hand, when the irradiation angle? 6 'exceeds 80 °, it is difficult to form the louver structure because the irradiation light is dispersed too much.

Therefore, it is more preferable to set the irradiation angle width 6 'of the irradiation angle 6 to a value within a range of 2 to 45 degrees, more preferably to a value within a range of 5 to 20 degrees.

Further, in the case of having the irradiation angle width 6 ', the angle at the precise intermediate position thereof is referred to as an irradiation angle 6.

It is also preferable that the first active energy ray irradiation is performed via the shield plate having the active energy ray transmitting portion on the long groove and the longitudinal direction of the active energy ray transmitting portion is a direction parallel to the longitudinal direction of the linear light source.

The active energy ray transmitting portion may be of any type as long as it is transparent to the active energy rays.

For example, it may be made of quartz glass, or may be a simple space in which no light shielding material is present.

Specifically, as shown in Fig. 12, a gap (active energy ray transmitting portion) formed in a long groove formed by the two light blocking plates 123 (123a and 123b) is interposed and the lengthwise direction of the gap in the long groove is , And the direction parallel to the long axis direction of the linear light source 125a.

By arranging the shielding plate like this, the irradiation angle 6 of the active energy ray 150a shown in Fig. 10 (a) can be adjusted to a value within a predetermined range, and the irradiation angle 6 on the surface of the first coated layer 1a This is because it is possible effectively to suppress irradiation of the active energy ray 150a from the linear light source 125a at an excessively different angle by each position.

As a result, the inclination angle of the plate-shaped area in the formed louver structure can be made uniform, and further, the light diffusion characteristics of the obtained long-axis light diffusion film can be made uniform.

The peak illuminance on the surface of the first coated layer in the first active energy ray irradiation is preferably set to a value within a range of 0.1 to 50 mW / cm 2.

This is because the first louver structure can be formed more efficiently by setting the peak illuminance in the first active energy ray irradiation to a value within this range.

That is, when the peak illuminance becomes less than 0.1 mW / cm 2, it may be difficult to clearly form the first louver structure. On the other hand, when the peak illuminance exceeds 50 mW / cm 2, it is estimated that the curing rate becomes too fast, so that the first louver structure can not be clearly formed.

Therefore, the peak illuminance on the surface of the first coated layer in the first active energy ray irradiation is more preferably in the range of 0.3 to 10 mW / cm 2, more preferably in the range of 0.5 to 5 mW / Is more preferable.

The term "peak roughness" as used herein means a measured value at a portion where the active energy ray irradiated on the surface of the first coating layer shows the maximum value.

It is also preferable that the accumulated light quantity on the surface of the first coated layer in the first active energy ray irradiation is within a range of 5 to 300 mJ / cm 2.

This is because the first louver structure can be formed more efficiently by setting the accumulated light amount in the first active energy ray irradiation to a value within this range.

That is, when the integrated amount of light is less than 5 mJ / cm 2, it may be difficult to sufficiently extend the first louver structure from the upward direction to the downward direction. On the other hand, when the total amount of accumulated light exceeds 300 mJ / cm 2, coloration may occur in the obtained light diffusion film.

Therefore, the total amount of light on the surface of the first coated layer in the first active energy ray irradiation is more preferably in the range of 10 to 200 mJ / cm 2, more preferably in the range of 20 to 150 mJ / Is more preferable.

It is also preferable to set the moving speed of the first coated layer to a value within a range of 0.1 to 10 m / min.

This is because the first louver structure can be formed more efficiently by setting the moving velocity of the first coated layer to a value within this range.

That is, when the moving speed of the first coated layer is less than 0.1 m / min, the productivity may be excessively lowered. On the other hand, when the moving speed of the first coated layer exceeds 10 m / min, the curing of the first coated layer, in other words, the formation of the first louver structure is faster than the forming of the first coated layer, And the formation of the first louver structure sometimes becomes insufficient.

Therefore, the moving speed of the first coated layer is more preferably in the range of 0.2 to 5 m / min, and more preferably in the range of 0.5 to 3 m / min.

It is also preferable to irradiate the active energy ray with the active energy ray transmitting sheet laminated on the upper surface of the first coated layer.

This is because by laminating an active energy ray transmitting sheet, the influence of oxygen inhibition can be effectively suppressed and the first louver structure can be formed more efficiently.

That is, by laminating the active energy ray transmitting sheet on the upper surface of the first coated layer, the upper surface of the first coated layer is stably prevented from contacting with oxygen, and the sheet is efficiently permeated to the first coated layer The active energy ray can be irradiated to the active energy ray.

As the active energy ray transmitting sheet, any of the process sheets described in the step (b) (coating step) can be used without particular limitation, provided that it can transmit active energy rays.

It is also preferable to further irradiate an active energy ray separately from the first active energy ray irradiation as the step (c) so that the first coated layer has an accumulated light quantity enough for curing.

Since the active energy ray at this time is intended to sufficiently cure the first coating layer, it is preferable to use random light in any traveling direction, not parallel light.

(4) Step (d): The second coating step

9 (c), the composition for the light diffusion film is applied to the first coating layer 1a 'on which the first louver structure 13a is formed, and the first coating layer 1a ') And a second coated layer 1b are formed.

When the active energy ray transmitting sheet is used to form the first louver structure 13a, the sheet is peeled to expose the surface of the applied layer 1a ', and then the above-described operation is performed.

The composition for a light diffusion film used for forming the second application layer 1b is preferably the same as the composition for a light diffusion film used for forming the first application layer 1a.

This is because, by using the same composition for a light diffusion film, reflection at the interface between the coating layer 1a 'and the coating layer 1b' can be suppressed and adhesion can also be improved.

Examples of the method for applying the composition for a light diffusion film on the first coating layer on which the first louver structure is formed include knife coating method, roll coating method, bar coating method, blade coating method, die coating method, A gravure coating method, or the like, as in the above-mentioned step (b).

Further, it is preferable that the film thickness of the second coating layer is set to a value within a range of 80 to 700 mu m.

This is because the second louver structure can be formed more efficiently by setting the film thickness of the second coating layer to a value within this range.

In other words, when the film thickness of the second coating layer is less than 80 占 퐉, the length of the second louver structure to be formed is insufficient, incident light which goes straight in the second louver structure increases, It is difficult to obtain the uniformity of the intensity of the diffused light. On the other hand, when the film thickness of the second coating layer exceeds 700 mu m, when the second coating layer is irradiated with the active energy ray to form the second louver structure, the light- The direction is diffused, and it may be difficult to form a desired louver structure.

Therefore, the film thickness of the second coated layer is more preferably in the range of 100 to 500 mu m, and more preferably in the range of 120 to 300 mu m.

(5) Step (e): the second activation energy ray irradiation step

As shown in Fig. 9 (d), in the step (e), the first coated layer 1a 'and the second coated layer 1b' in which the first louver structure 13a is formed are formed on the second coated layer 1b As a step of forming the second louver structure 13b by irradiating the second active energy ray using the linear light source 125b while moving the laminated body 1c made of the first louver structure 13b as shown in Fig. 11 (b) Likewise, when viewed from above the film, the acute angle between the long axis direction of the linear light source 125a in the first activation energy ray irradiation and the long axis direction of the linear light source 125b in the second activation energy ray irradiation ? 1 ') in the range of 10 to 90 degrees.

That is, by defining the relationship of the arrangement angles of the respective linear light sources within a predetermined range in the two active energy ray irradiation processes using the linear light sources, the extending direction of the plate-shaped region in the first louver structure and the The elongated light diffusion film formed by crossing the extending direction of the plate-shaped regions in the two-louver structure at a predetermined angle can be efficiently produced.

Therefore, by optically diffusing the incident light not only in the direction along the longitudinal direction but also in the direction orthogonal to the longitudinal direction, it is possible to efficiently manufacture a long-length light diffusion film effectively widening the diffusion area of the incident light.

More specifically, it is possible to obtain an elongated light diffusion film capable of diffusing incident light in a direction along its longitudinal direction and in a direction perpendicular to its longitudinal direction, without connecting a plurality of light diffusion films as in the conventional art have.

That is, when the acute angle? 1 'shown in FIG. 11 (b) is less than 10, the diffusion area of the incident light may be excessively small.

Therefore, when viewed from above the film, an acute angle (? 1 ') formed by the long axis direction of the linear light source in the first activation energy ray irradiation and the long axis direction of the linear light source in the second activation energy ray irradiation is set to 80 - More preferably in the range of 90 to 90 degrees, more preferably in the range of 85 to 90 degrees, and still more preferably in the range of 89 to 90 degrees.

11 (b), when viewed from above the film, the direction of the long axis of the linear light source 125b in the second active energy ray irradiation and the direction of the long axis of the linear light source 125b in the first louver structure 13a The acute angle? 'Formed by the imaginary line E' along the moving direction E of the layered product 1c composed of the coated layer 1a 'and the second coated layer 1b is within a range of 10 to 80 ° Value.

The reason for this is that by defining the arrangement angle of the linear light sources in this way, in addition to the arrangement angle of the linear light sources in the above-described step (c), the incident light is directed not only in the direction along the long direction, It is possible to manufacture a long-length light diffusion film effectively widening the diffusion area of incident light more efficiently.

That is, when the angle θ3 'is less than 10 °, the light diffusion property in the direction along the longitudinal direction of the film is excessively decreased This is because the diffusion area of the incident light may be excessively small. On the other hand, when the angle θ3 'exceeds a value of 80 °, the light diffusing characteristics in the direction perpendicular to the longitudinal direction of the film generally change depending on the arrangement angle of the linear light sources in the above-described step (c) , And the diffusion area of the incident light may be excessively small.

Therefore, when viewed from above the film, the angle formed by the long axis direction of the linear light source in the second activation energy ray irradiation and the virtual line in the moving direction of the laminate composed of the first coating layer and the second coating layer more preferably in a range of 40 to 50 degrees, and still more preferably in a range of 44 to 46 degrees.

It is preferable that the gap between the linear light sources 125b and the coating layer 1b is substantially the same at any position.

The irradiation angle and the irradiation angle width of the active energy ray are preferably in the same numerical range as in the case of the first active energy ray irradiation described with reference to Figs. 10 (a) to 10 (b).

11 (b), when viewed from above the film, the direction of the long axis of the linear light source 125a in the first active energy ray irradiation and the direction of the long axis of the linear light source 125a in the second active energy ray irradiation, Symmetrical with respect to a virtual line E "perpendicular to the moving direction E of the laminated body composed of the first coated layer 1a 'and the second coated layer 1b in the major axis direction of the first coated layer 125b desirable.

This is because, by arranging the linear light source in the second activation energy ray irradiation in this manner, incident light can be more uniformly diffused in the obtained light diffusion film.

In particular, when θ 2 '= 45 ° and θ 3' = 45 °, or when each is a peripheral value, by arranging the line-shaped light sources so as to be in line symmetry, spreading of the diffused light in the left- Respectively, to the maximum extent possible.

Therefore, when such a light diffusion film is applied to a large-screen projection screen, the viewing angle in the lateral direction and the viewing angle in the longitudinal direction can be maximized.

As shown in Fig. 12, for the same reason as in the case of irradiation with the first active energy ray, the second active energy ray irradiation is carried out through a gap in the form of a long groove formed by two shading plates, It is preferable that the longitudinal direction of the gap is a direction parallel to the longitudinal direction of the linear light source.

The peak illuminance on the surface of the second coated layer in the second active energy ray irradiation is preferably set to a value within a range of 0.1 to 50 mW / cm 2.

This is because the second louver structure can be formed more efficiently by setting the peak illuminance in the second active energy ray irradiation to a value within this range.

That is, when the peak illuminance becomes less than 0.1 mW / cm 2, it may be difficult to clearly form the second louver structure. On the other hand, if the peak illuminance exceeds 50 mW / cm 2, it is estimated that the curing rate becomes too fast, so that the second louver structure can not be clearly formed.

Therefore, the peak illuminance on the surface of the second coated layer in the second active energy ray irradiation is more preferably in the range of 0.3 to 10 mW / cm 2, more preferably in the range of 0.5 to 5 mW / Is more preferable.

In addition, it is preferable that the integrated light quantity on the surface of the second coated layer in the second active energy ray irradiation is set to a value within a range of 5 to 300 mJ / cm 2.

This is because the second louver structure can be formed more efficiently by setting the accumulated light quantity in the second active energy ray irradiation to a value within this range.

That is, when the integrated amount of light is less than 5 mJ / cm 2, it may be difficult to sufficiently extend the second louver structure from above to below. On the other hand, when the total amount of accumulated light exceeds 300 mJ / cm 2, coloration may occur in the obtained light diffusion film.

Therefore, it is more preferable to set the accumulated light quantity on the surface of the second coated layer in the second active energy ray irradiation to a value within the range of 10 to 200 mJ / cm2, more preferably within the range of 20 to 150 mJ / Is more preferable.

Also in the second activation energy ray irradiation, the moving speed of the laminated body composed of the first coated layer and the second coated layer in which the first louver structure is formed is set to 0.1 to 10 m / Min, more preferably in the range of 0.2 to 5 m / min, and more preferably in the range of 0.5 to 3 m / min.

It is also preferable to irradiate the active energy ray with the active energy ray transmitting sheet laminated on the upper surface of the second coated layer from the viewpoint of the case of the step (c).

It is also preferable to further irradiate an active energy ray separately from the second active energy ray irradiation as the step (e) so that the second coated layer has an accumulated light quantity enough for curing.

Since the active energy ray at this time is intended to sufficiently cure the second coated layer, it is preferable to use random light in any traveling direction, not parallel light.

The above-described steps (d) to (e) may be carried out continuously with the steps (b) to (c) using one conveyor, (D) to (e) may be carried out by bringing the first coated layer having the first coating layer formed thereon into a roll form and collecting it on a separate conveyor.

Therefore, in the former case, the linear light source in the step (c) and the linear light source in the step (e) are separately provided. In the latter case, the same linear light source is changed It is also possible to use it.

[Example]

Hereinafter, the method for producing the light-diffusing film of the present invention will be described in more detail with reference to Examples.

[Example 1]

1. Synthesis of Low Refractive Index Polymerizable Compound (B) Component

2 moles of isophorone diisocyanate (IPDI) as a component (B1) and 2 moles of 2-hydroxyethyl (meth) acrylate as a component (B3) were added to 1 mole of polypropylene glycol (PPG) having a weight average molecular weight of 9,200 as a component (B2) After 2 moles of methacrylate (HEMA) was accommodated, polymerization was carried out according to a conventional method to obtain polyether urethane methacrylate having a weight average molecular weight of 9,900.

The weight average molecular weight of polypropylene glycol and polyether urethane methacrylate is a polystyrene reduced value measured by gel permeation chromatography (GPC) under the following conditions.

GPC measurement apparatus: HLC-8020 manufactured by TOSOH CORPORATION

GPC column: manufactured by TOSOH CORPORATION (hereinafter referred to as the order of passage)

TSK guard column HXL-H

TSK gel GMHXL (× 2)

TSK gel G2000HXL

Measurement solvent: tetrahydrofuran

· Measuring temperature: 40 ℃

2. Preparation of composition for light diffusion film

Subsequently, 100 parts by weight of polyether urethane methacrylate having a weight average molecular weight of 9,900 as component (B) was mixed with 100 parts by weight of o-phenylphenoxyethoxy having a weight average molecular weight of 268 represented by the following formula (3) 100 parts by weight of ethyl acrylate (NK Ester A-LEN-10, manufactured by Shin-Nakamura Chemical Co., Ltd.) and 5 parts by weight of 2-hydroxy-2-methylpropiophenone as component (C) Lt; 0 > C, to obtain a composition for a light diffusion film for forming the first louver structure and the second louver structure.

The refractive indices of the component (A) and the component (B) were measured according to JIS K0062 using an Abbe refractometer (Abe Refractometer DR-M2, Na light source, wavelength 589 nm) And 1.46.

3. First coating step

Subsequently, the resulting composition for a light diffusion film was applied to a transparent polyethylene terephthalate film (hereinafter referred to as PET) as a process sheet to form a first coated layer having a thickness of 165 탆.

4. First active energy irradiation process

Subsequently, an ultraviolet irradiator (ECS-4011GX, manufactured by Eye Graphics Co., Ltd.) to which a cold mirror for condensing was attached was attached to a line-shaped high-pressure mercury lamp as shown in Fig. 10 (a).

At this time, when viewed from above the film, an ultraviolet irradiating device was provided such that the acute angle? 2 formed by the imaginary line along the long axis direction of the linear light source and the moving direction of the first coated layer was 45 degrees.

Next, when a shading plate is provided on the periphery of the heat-cut filter and the normal line of the surface of the first coating layer when the ultraviolet rays irradiated to the surface of the first coating layer is viewed from the long axis direction of the linear light source is 0 DEG, And the irradiation angle of the direct ultraviolet ray from the linear light source (? 6 in FIG. 10 (b)) was set to 16 degrees.

The height from the surface of the first coating layer to the linear light source was set to 2000 mm, the peak illuminance was set to 1.26 mW / cm 2, and the accumulated light amount was set to 23.48 mJ / cm 2.

Further, in order to prevent reflected light from the shading plate or the like from becoming stray light inside the irradiation device and affecting the light curing of the first coated layer, two shading plates are provided in the vicinity of the conveyor as shown in Fig. 12, And only ultraviolet light emitted directly from the light source was irradiated onto the first coated layer.

More specifically, as shown in Fig. 12, it is arranged such that a gap (gap width: 35 cm) in a long groove formed by two shading plates is formed, and the longitudinal direction of the gap in the long groove is aligned with the long axis direction So as to be parallel to the direction of the vehicle.

Subsequently, the first coated layer was irradiated with ultraviolet rays while moving the first coated layer in the rightward direction in Fig. 9 (b) at a speed of 1.0 m / min by a conveyor, and the length in the longitudinal direction (moving direction of the first coated layer) A length of 1.4 m, and a film thickness of 165 mu m was formed on the first coated layer.

Subsequently, in order to ensure reliable curing, a release film (SP-PET382050, manufactured by LINTEC CO., LTD.) Having ultraviolet transmittance of 38 mu m in thickness as an active energy ray transmissive sheet was coated on the exposed surface side of the first coated layer, A haze value of 1.80%, an image clarity of 425, and a transmittance of 84.3% at a wavelength of 360 nm).

Then, scattered light irradiation was performed so that the peak illuminance was 13.7 mW / cm 2 and the accumulated light amount was 213.6 mJ / cm 2.

The above-mentioned peak illuminance and the accumulated light amount were measured by placing a UV meter (UV-IR integrated light meter UVPF-A1 manufactured by Eye Graphics Co., Ltd.) equipped with a light receiver at the position of the first coating layer.

The film thickness of the obtained first coating layer having the first louver structure was measured using a static pressure gauge (Techrak PG-02J manufactured by Takara Shuzo Co., Ltd.).

5. Second coating step

Then, the active energy ray transmitting sheet was peeled off from the first coating layer on which the obtained first long luer structure was formed.

Subsequently, the composition for a light-diffusing film obtained in the above-mentioned process was applied to the exposed surface of the first coated layer having the obtained long-lipped first louver structure to form a second coated layer having a thickness of 165 탆.

6. Second active energy irradiation process

Then, when viewed from above the film, an acute angle &thetas; 1 between the long axis direction of the linear light source in the first activation energy ray irradiation and the long axis direction of the linear light source in the second activation energy ray irradiation is 90 DEG Except that the ultraviolet irradiator is provided so as to irradiate ultraviolet rays in the same manner as the first active energy ray irradiating process, a long-lived light diffusion film having a first louver structure and a second louver structure and having a thickness of 330 m .

Further, when viewed from above the film, the acute angle? 3 formed by the imaginary line along the moving direction of the laminate composed of the long axis direction of the linear light source and the first coated layer and the second coated layer in which the first louver structure is formed 45 °.

Furthermore, even after the ultraviolet rays were irradiated onto the second coated layer, scattered light was irradiated in a state of being laminated with an active energy ray transmitting sheet (a releasing film having ultraviolet ray permeability) as in the case of the first coated layer, thereby surely curing .

As shown in Fig. 13, the obtained light-diffusing film has a structure in which the extending direction of the plate-like region in the first louver structure and the extending direction of the plate-shaped region in the second louver structure are It was confirmed that the acute angle formed was 90 °.

Further, it was confirmed that when viewed from above the film, the acute angle formed by the extending direction of the plate-like region in the first louver structure and the longitudinal direction of the film was 45 °.

Further, it was confirmed that when viewed from above the film, the acute angle formed by the extending direction of the plate-like region in the second louver structure and the longitudinal direction of the film was 45 °.

Fig. 14 (a) is a photograph of a cross section of the resulting light-diffusing film taken along a plane orthogonal to the longitudinal direction of the film, and a photograph of a cross section of the cross-section taken parallel to the longitudinal direction of the film and perpendicular to the film plane And Fig. 14 (b), respectively.

The light-diffusing film was cut using a razor, and a photographing optical microscope (reflection observation) of a cross-sectional photograph was used.

7. Measurement

As shown in Fig. 13, light was incident on the film from the lower side (the side where the first louver structure is located) of the obtained light diffusion film in a direction perpendicular to the film surface.

Subsequently, a spectral chart of diffused light in a direction perpendicular to the longitudinal direction of the film and in a direction parallel to the longitudinal direction of the film was obtained by using a side color meter (VC-2, manufactured by Suga Shikeki Co., Ltd.) .

That is, as shown in Fig. 15A, when the light diffusion angle (DEG) in the diffused light diffused by the light diffusion film is taken as the abscissa and the relative intensity (-) of the diffused light is taken as the ordinate A spectrum chart was obtained.

Here, the spectrum chart A shown in Fig. 15 (a) corresponds to the diffused light in the direction perpendicular to the longitudinal direction of the film, and the spectrum chart B shows the diffusions in the direction parallel to the longitudinal direction of the film Light.

Further, as shown in Fig. 15 (b), a photograph of the diffused light when viewed from the Z direction in Fig. 13 was obtained using a conoscope (manufactured by autronic-MELCHERS GmbH).

The results shown in Figs. 15 (a) to 15 (b) were consistent with the light diffusion characteristics predicted from the film having the internal structure as shown in Fig.

[Referential Example 1]

In Reference Example 1, in the first active energy ray irradiation step, when viewed from above the film, the acute angle &thetas; 2 between the longitudinal direction of the linear light source and the imaginary line along the moving direction of the first coated layer is 90 DEG , The first coating layer was subjected to the first activation energy ray irradiation step as in Example 1 to obtain a first coating layer (one having the first louver structure formed therein).

As shown in Fig. 16 (a), the first coating layer formed with the obtained first louver structure has an acute angle formed by the extending direction of the plateau region in the louver structure and the acute angle Was found to be 90 °.

Subsequently, as shown in Fig. 16 (b), the elongated first coating layer having the obtained first louver structure was cut every 1.1 m in the longitudinal direction to form a plurality of spool-like first coatings Layer.

Subsequently, as shown in Fig. 16 (c), the plurality of spool-shaped first coating layers on which the obtained first louver structure is formed are rotated 90 degrees in the respective planes, side by side, Respectively.

16 (c), when viewed from above the film, a first louver structure having an acute angle formed by the extending direction of the plate-shaped region in the louver structure and its longitudinal direction is formed Thereby obtaining a first coating layer of a long-form phase (the first louver structure was formed inside).

16 (c), the long coat layer shown in Fig. 16 (a) was applied to the first coating layer of the elongated phase formed with the obtained first louver structure through an acrylic pressure-sensitive adhesive layer having a thickness of 25 占 퐉 As a second coating layer of a elongated phase having a second louver structure, to obtain a light diffusion film.

As shown in Fig. 17, the obtained light-diffusing film has a structure in which the direction of extension of the plate-shaped area in the first louver structure and the direction of extension of the plate-shaped area in the second louver structure area And the acute angle formed by this was 90 °.

Further, it was confirmed that when viewed from above the film, the acute angle formed by the extending direction of the plate-shaped area in the first louver structure and the longitudinal direction of the film was 0 °.

It was confirmed that when viewed from above the film, the acute angle formed by the extending direction of the plate-like region in the second louver structure and the film longitudinal direction was 90 °.

Fig. 18 (a) is a photograph of a section obtained by cutting the obtained light-diffusing film at a plane orthogonal to the longitudinal direction of the film, and Fig. 18 And Fig. 18 (b), respectively.

Further, as in Example 1, the light diffusing state in the case where light was incident on the film from the lower side of the resultant light-diffusing film in a direction perpendicular to the film surface was measured.

Fig. 19 (a) shows a spectrum chart of the diffused light obtained by introducing light into the jointless portion, and Fig. 19 (b) shows a photograph of the diffused light when the diffracted light is viewed in the Z direction in Fig.

The results shown in Figs. 19 (a) and 19 (b) were consistent with the light diffusion characteristics predicted from the film having the internal structure as shown in Fig.

However, in the case where light was incident on the joint portion, as shown in Figs. 20 (a) and 20 (b), it was confirmed that the light diffusing property tended to become uneven due to the joint portion of the film.

[Comparative Example 1]

In Comparative Example 1, a light diffusion film was produced in the same manner as in Example 1 except that the second coating step and the second activation energy radiation step were not performed.

As shown in Fig. 21, the resulting light-diffusing film was confirmed to have an acute angle formed by the extending direction of the plate-shaped region in the louver structure and the longitudinal direction of the film at 45 degrees when viewed from above the film.

Fig. 22 (a) is a photograph of a section taken along the plane perpendicular to the longitudinal direction of the film, and Fig. 22 (b) is a photograph taken along the plane parallel to the longitudinal direction of the film and perpendicular to the film plane And Fig. 22 (b), respectively.

Further, as in Example 1, the light diffusing state in the case where light was incident on the film from the lower side of the resultant light-diffusing film in a direction perpendicular to the film surface was measured.

A spectrum chart of the obtained diffused light is shown in Fig. 23 (a), and a photograph of the diffused light in the case of looking in the Z direction in Fig. 21 is shown in Fig. 23 (b).

23 (a) shows a spectrum chart in the direction along the diffusion direction (long axis direction) of the diffused light shown in Fig. 23 (b).

The results shown in Figs. 23 (a) to 23 (b) were consistent with the light diffusion characteristics predicted from the film having the internal structure as shown in Fig.

As described above, according to the present invention, by performing the predetermined manufacturing method, the extending direction of the plate-shaped area in the first louver structure and the extending direction of the plate- It is possible to obtain an elongated light diffusion film formed by crossing at a predetermined angle.

As a result, in the long-axis light diffusion film, the diffusion area of the incident light can be effectively widened by diffusing the incident light not only in the direction along the longitudinal direction but also in the direction orthogonal to the longitudinal direction.

Therefore, it is expected that the light-diffusing film of the present invention contributes significantly to the productivity and high-quality of a large-area light-diffusing film used particularly in a projection screen, a reflection type liquid crystal device, and the like.

1a: a first coating layer, 1a ': a first coating layer having a first louver structure, 1b: a second coating layer, 1c: a laminate composed of a first coating layer and a second coating layer, 2: 13: louver structure, 13: louver structure, 14: relatively low refractive index plate, 13: louver structure, 13: louver structure, 13: Light diffusing film obtained by the manufacturing method of the present invention, 50 ': diffusion state of light, 51': diffusion state of diffused light, 120: ultraviolet ray irradiating device, 121: heat ray cut filter, 123: shading plate, 125: Light source, 150: active energy ray

Claims (8)

As a long-lived light diffusion film having a first louver structure and a second louver structure sequentially from below in accordance with the film thickness direction,
Wherein the first louver structure and the second louver structure each comprise a plurality of plate-shaped regions having different refractive indices and the plurality of plate-shaped regions having different refractive indices are alternately arranged in an arbitrary direction along the film plane And further,
An acute angle &thetas; 1 between the extending direction of the plate-shaped area in the first louver structure and the extending direction of the plate-shaped area in the second louver structure is 10 to 90 degrees Value within the range,
(2) between the extending direction of the plate-shaped region in the first louver structure and the longitudinal direction of the film is set to a value within a range of 10 to 80 degrees, The angle? 3 formed by the extending direction of the plate-shaped area in the second louver structure and the longitudinal direction of the film is set to a value within a range of 10 to 80 degrees,
Wherein the light diffusion film has a length in a short direction within a range of 0.1 to 3 m and a length in a long direction of 15 m or more. delete The method according to claim 1,
Wherein an extension direction of the plateau region in the first louver structure and an extending direction of the plateau region in the second louver structure are set so as to be substantially parallel to a virtual line perpendicular to the longitudinal direction of the film , ≪ / RTI > and a line symmetry. delete The method according to claim 1,
A light diffusing film formed by winding in roll form. The method according to claim 1,
Wherein the first louver structure and the second louver structure each have a thickness within a range of 50 to 500 mu m. The method according to claim 1,
Wherein the widths of the plate-shaped regions in the first louver structure and the second louver structure are set to values within a range of 0.1 to 15 占 퐉, respectively. The method according to claim 1,
Wherein the raw material of the light diffusion film is a composition for a light diffusion film containing two polymerizable compounds having different refractive indexes.

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