KR102000510B1 - Producing method for light diffusion film - Google Patents

Abstract

An object of the present invention is to provide a method of manufacturing a light diffusion film capable of efficiently producing an elongated light diffusion film effectively widening the diffusion area of incident light.
In order to solve such a problem, a method for producing a long-lived light diffusion film having a predetermined louver structure includes the following steps (a) to (e).
(a) preparing a composition for a light diffusion film
(b) a step of forming a first coated layer
(c) a step of forming a first louver structure by irradiating the first applied layer with a first active energy ray using a linear light source
(d) a step of forming a laminate composed of the first coating layer and the second coating layer
(e) a step of forming a second louver structure by irradiating the second coating layer with a second active energy ray using a linear light source, wherein, when viewed from above the film, in the first active energy ray irradiation Of the linear light source in the second active energy ray irradiation is set to a value within a range of 10 to 90 degrees.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a light-

The present invention relates to a method for producing a light diffusion film.

Particularly, it is an object of the present invention to provide a light diffusion film capable of efficiently producing a long-lived light diffusion film in which the diffusion area of 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 thereof ≪ / RTI >

Conventionally, for example, in the field of optical technology to which a liquid crystal display device belongs, light is diffused in a specific direction with respect to incident light from a specific direction, and light diffusion The use of films 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 comprising a plurality of compounds each having at least one polymerizable carbon-carbon double bond in a molecule having a difference in refractive index is kept in a film form, A second step of irradiating ultraviolet rays to cure the composition, and a second step of holding the resin composition in a film form on the cured product obtained and irradiating ultraviolet rays from a direction different from the first step to cure the composition, (Light diffusing film) is produced by repeating the above-described two steps.

In Patent Document 2, there is an angle dependence of cloudiness, 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 (Light diffusing films) each having a thickness of 30 占 or more, as shown in Figs. 23 (a) to 23 (b) Film) is laminated so that the directions of light scattering angles (light diffusion angle of incidence angles) are almost orthogonal 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 of continuously mass-producing the light diffusion film, the coating layer comprising the composition for the light diffusion film is moved to a conveyor or the like, and the active energy ray is irradiated to the coating layer using a linear light source , A light diffusion film having a predetermined louver structure is produced.

Therefore, in the case of Patent Document 1, although it is possible to obtain a light diffusion film for optically diffusing incident light in a moving direction of a coating layer, that is, in a direction along a longitudinal direction of the film, 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 so that the long axis direction of the linear light source is in a direction corresponding to the moving direction of the coating layer.

However, even if the linear light sources are disposed as such, since 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 applied layer as viewed from the end face in the moving direction of the applied layer , The light diffusion characteristics of the resulting light diffusion film are uneven.

Therefore, in Reference 1, when it is desired to obtain a long-lived light diffusion film for diffusing incident light in a direction orthogonal to its longitudinal direction, first, a plate-shaped region is arranged along the width direction when the film is viewed from the upper surface 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 to each other. As a result, there has been a problem that the light diffusing property at the joint portion becomes uneven, or the strength of the film tends to be lowered.

Further, in the cited document 1, the extending direction of the plate-shaped area in the louver structure obtained in the first step and the extending direction of the plate-shaped area in the louver structure obtained in the second step are basically parallel.

Therefore, it is basically impossible to diffuse the incident light even in the direction perpendicular to the longitudinal direction thereof.

On the other hand, in Patent Document 2, as shown in Figs. 23A and 23B, two of the plurality of light diffusion films are laminated so that the directions of the light diffusion incidence angle regions are almost orthogonal to each other, 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, in the case of Patent Document 2, when the light diffusion film is continuously mass-produced, the active energy ray is irradiated using a linear light source while moving the coating layer made of the composition for light diffusion film to a conveyor or the like.

Therefore, it is difficult to obtain the light diffusion film 221 for diffusing the incident light in the direction orthogonal to the longitudinal direction of the film as shown in Fig. 23 (a) for the same reason as in the case of Patent Document 1. Fig.

Consequently, even if the light diffusion film disclosed in Patent Document 2 is intended to obtain a long-length light diffusion film 221 that light-diffuses the incident light shown in FIG. 23 (a) in a direction perpendicular to the longitudinal direction, It is necessary to connect the plurality of light diffusion films to each other, so that the light diffusibility becomes uneven at 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 optically diffusing the incident light not only in the direction along the longitudinal direction but also in the direction orthogonal to the longitudinal direction.

Under these circumstances, there has been a demand for an elongated light diffusion film which is easy to apply to a large-screen screen or the like and does not cause problems such as seams.

That is, there has been a demand for a method of manufacturing an elongated light diffusion film in which incident light is effectively diffused not only in a direction along its longitudinal direction but also in a direction orthogonal to its longitudinal direction, thereby effectively expanding the diffusion area of incident light.

In view of the above circumstances, the inventors of the present invention have found that, in a predetermined manufacturing method including two active energy ray irradiation processes using a linear light source, in the two active energy ray irradiation processes It is possible to obtain a long-length light-diffusing film which solves the above-mentioned problem by defining the relationship of the arrangement angles of the linear light sources of the respective light sources of the respective light sources in a predetermined range.

That is, an object of the present invention is to provide a light-diffusing film which can efficiently produce a long-lived light diffusion film in which the diffusion area of incident light is effectively widened by optically diffusing not only the direction along the long direction but also the direction orthogonal to the long direction And a method for producing the light diffusion film.

According to the present invention, the first louver structure and the second louver structure in which a plurality of plate-shaped regions having different refractive indexes are alternately arranged in parallel in an arbitrary one direction along the film plane, A method for producing a light diffusion film comprising the following steps (a) to (e) is provided, and the above-described problems can be solved.

(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 and forming 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) a step of applying a composition for a light diffusion film to the first coating layer on which the first louver structure is formed, and forming a laminate composed of the first coating layer and the second coating layer

(e) a step of forming a second louver structure by irradiating a second coating layer with a second active energy ray irradiation using a linear light source while moving a laminate composed of the first coating layer and the second coating layer , 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 10 to 90 DEG Lt; RTI ID = 0.0 >

That is, in the method of manufacturing a light diffusion film of the present invention, the relationship of the arrangement angles of the respective linear light sources in the active energy ray irradiation process using two linear active energy sources is defined within a predetermined range. It is possible to efficiently produce an elongated light diffusion film in which the extending direction of the plate-shaped area of the first louver structure and the extending direction of the plate-shaped area of the second louver structure intersect at a predetermined angle.

Accordingly, 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 in which the diffusion area of the incident light is effectively widened.

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 orthogonal to its longitudinal direction, without connecting a plurality of light diffusion films as in the conventional art have.

In the process of producing the light diffusion film of the present invention, in the step (c), when viewed from above the film, the direction of the major axis of the linear light source in the first active energy ray irradiation, 2 is set to a value within a range of 10 to 80 DEG and the angle of incidence of the second active energy rays in the step of irradiating the second active energy rays It is preferable that the acute angle? 3 formed by the long axis direction of the linear light source and the virtual line along the moving direction of the laminate composed of the first coated layer and the second coated layer is within a range of 10 to 80 degrees.

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

In the process (e) of the present invention, when viewed from above the film, the long axis direction of the linear light source in the first active energy ray irradiation and the second active energy It is preferable that the longitudinal direction of the linear light source in the first irradiation is linearly symmetrical with respect to a virtual line perpendicular to the moving direction of the laminate composed of the first coating layer and the second coating layer.

By doing so, it is possible to more uniformly diffuse the incident light in the obtained light diffusion film.

In carrying out the method for producing a light diffusion film of the present invention, in the step (c) and the step (e), the first active energy ray irradiation and the second active energy ray irradiation are repeated, It is preferable that the shading plate is interposed and the longitudinal direction of the active energy ray transmitting portion is parallel to the longitudinal direction of the linear light source.

By doing so, it is possible to manufacture a long-length light diffusion film effectively widening the diffusion area of the incident light 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.

In carrying out the process for producing a light-diffusing film of the present invention, in the step (c), the peak illuminance on the surface of the first coated layer in the first active energy ray irradiation is preferably in the range of 0.1 to 50 mW / And the accumulated light quantity on the surface of the first coated layer is preferably set to a value within a range of 5 to 300 mJ / cm < 2 >.

By doing so, the first louver structure can be formed more efficiently.

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 a maximum value.

In carrying out the method for producing a light diffusion film of the present invention, in the step (e), the peak illuminance on the surface of the second coating layer in the second activation energy ray irradiation is in the range of 0.1 to 50 mW / And the integrated amount of light on the surface of the second coated layer is preferably within a range of 5 to 300 mJ / cm 2.

By doing so, the second louver structure can be formed more efficiently.

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 second coating layer shows a maximum value.

Further, in carrying out the method for producing a light diffusion film of the present invention, in the step (b), the film thickness of the first coated layer is set to a value within a range of 80 to 700 mu m, 2 The coating thickness of the coating layer is preferably within the range of 80 to 700 mu m.

By doing so, the first and second louver structures can be formed more efficiently.

In carrying out the method for producing a light-diffusing film of the present invention, it is preferable that the moving speed of the first coated layer in the step (c) and that of the laminated body composed of the first coated layer and the second coated layer in the step It is preferable to set the moving speed to a value within a range of 0.1 to 10 m / min.

This is because the first louver structure and the second louver structure can be formed more efficiently.

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

An embodiment of the present invention is characterized in that a first louver structure and a second louver structure formed by alternately arranging a plurality of plate-shaped regions having different refractive indexes in an arbitrary one direction along the film plane in parallel from the downward direction Is a process for producing a light diffusion film characterized by comprising 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 and forming 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) a step of applying a composition for a light diffusion film to the first coating layer on which the first louver structure is formed, and forming a laminate composed of the first coating layer and the second coating layer

(e) a step of forming a second louver structure by irradiating a second coating layer with a second active energy ray irradiation using a linear light source while moving a laminate composed of the first coating layer and the second coating layer , 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 10 to 90 DEG Lt; RTI ID = 0.0 >

Hereinafter, embodiments of the present invention will be described concretely with reference to the drawings (appropriately). In order to facilitate understanding of these descriptions, first, the basic principle of light diffusion in a light diffusion film, The basic structure of a predetermined light-diffusing film obtained by the method for producing a light-diffusing 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 from the arrow direction.

2 (a) is an overall view of the light diffusion film 10, and Fig. 2 (b) is a sectional view when the light diffusion film 10 of Fig. 2 (a) is viewed from the X direction .

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.

In other words, when the film is mounted on a horizontal plane, it has a louver structure composed of a plate-like area extending in the horizontal direction in the film.

1 (b), the plate-shaped region 12 having a relatively high refractive index and the plate-shaped region 14 having a relatively low refractive index each have a predetermined thickness, and the light-diffusing film 10, In the normal direction (film thickness direction).

Thus, 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, Incident light 52 or 54 passes through the inside of the relatively high refractive index plate-shaped area 12 in the louver structure along the film thickness direction while changing the direction, It is presumed that the traveling direction is not the same.

As a result, it is assumed that 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 diffusing film 10 deviates from the light diffusing incident angle range, the incident light 56 is not diffused by the light diffusing film as shown in Fig. 1 (b) It is presumed to transmit the light diffusion film 10 (56 ').

Further, in the present invention, the "light diffusion angle of incidence angle region" means the angular range of the incident light corresponding to the light diffusion film in order to diffuse the diffused light when the angle of the incident light from the point light source is changed .

Such a "light diffusion angle of incidence angle region" is an angle region determined for each light diffusion film in accordance with the difference in refractive index or the 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) .

In addition, 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), when the incident light is diffused by the film, the diffusion of the light in the plane parallel to the film in the diffused outgoing light Means that the state (the shape of the spread of the diffused light) has different properties depending on the direction in the same plane.

More specifically, as shown in Fig. 2 (a), among the components contained in the incident light, light is selectively diffused with respect to the component perpendicular to the direction of the louver structure extending along any one direction along the film plane , Anisotropic light diffusion is realized because light is hardly diffused for components parallel to the direction of the louver structure extending along any one direction along the film plane among the components contained in the incident light.

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

As described above, since the component of the incident light contributing to the light diffusion is a component perpendicular to the direction of the louver structure that extends mainly along any one direction along the film plane, as shown in Fig. 2 (b) In the present invention, the term "incident angle? 4" of 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 diffusion film with respect to the normal is 0 °.

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

In the present invention, the term " open angle of diffused light " means the width of the above-described "light diffusion angle region", and as shown in Fig. 2 (b), a louver structure extending in any one direction along the film plane Means an opening angle? 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 incident light is included in the light diffusion angle of incidence, the light diffusing film can diffuse substantially the same light on the light exiting surface side even when the incident angle is different.

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

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 direction changes in a zigzag pattern by the total internal reflection shown in Fig. 1 (b) It may be considered to be a gradient index type that changes direction.

1 (a) and 1 (b) show a straight line in order to simplify the interface between the plate-shaped region 12 having a relatively high refractive index and the plate-shaped region 14 having a relatively low refractive index, , And the interface slightly meanders, and each plate-shaped region forms a complex refractive index distribution structure accompanied by branching or disappearance.

As a result, it is presumed that they act complicatedly due to the light diffusion characteristics.

2. Basic Configuration

Next, the basic structure of the light diffusion film obtained by the production method of the present invention will be described with reference to Fig.

That is, as shown in Fig. 3 (c), the light diffusion film 20 obtained by the manufacturing method of the present invention has the first louver structure 13a shown in Fig. 3 (a) And the louver structure 13b are sequentially arranged 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) In contrast, when viewed from above the film, they cross each other.

Therefore, in the light diffusion film 20 obtained by the manufacturing method of the present invention, the light incident on the film can be, for example, first irradiated by the second louver structure 13b as shown in Fig. 3 (b) Anisotropic light is diffused.

Subsequently, the anisotropically diffused diffused light is diffused by the second louver structure 13b in the direction different from the second louver structure 13b by the first louver structure 13a as shown in Fig. 3 (a) Anisotropic light is diffused.

As a result, as shown in Fig. 3 (c), the 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 it does not restrict the vertical direction of the light diffusion film itself.

The term " diffusion area of incident light " means that, when the incident light is diffused by the film, as shown in Fig. 3 (c), in the plane parallel to the film at a predetermined distance from the film in the diffused outgoing light Of the diffused light.

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

3. Process (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, it is preferable to mix at least two polymerizable compounds having different refractive indexes, a photopolymerization initiator, and other additives as desired.

While mixing, the mixture may be stirred at room temperature, but from the viewpoint of improving uniformity, it is preferable to mix the mixture under a warming condition of 40 to 80 캜 to prepare a homogeneous mixture.

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) High refractive index polymerizable compound

(1) -1 type

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

The reason for this is as follows. When the polymerization rate of the component (A) is lower than that of the polymerizable compound (hereinafter referred to as the component (B)) having a relatively low refractive index by containing a specific (meth) Is higher than the polymerization rate of the two components, and it is presumed that the polymerization rate of the two components can be effectively lowered by causing a predetermined difference in the polymerization rate between these 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.

(B) in a plurality of linked steps in the course of the polymerization while having sufficient compatibility with the component (B) in the step of the monomers by containing the specific (meth) acrylic acid ester as the component (A) It is presumed that the compatibility with the component can be lowered to a predetermined range and the louver structure can be formed more efficiently.

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-shaped region derived from the component (B) is increased by containing the specific (meth) acrylic acid ester as the component (A) Can be adjusted to a predetermined value or more.

Therefore, by containing the specific (meth) acrylic acid ester as the component (A), a louver structure in which plate-shaped regions having different refractive indexes are alternately extended can be efficiently obtained in addition to the characteristics of the component (B) described later.

Further, the "(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 is, independently of each other and have, 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 the biphenyl compound having a specific structure is contained as the component (A), so that a predetermined difference in polymerization rate between the component (A) and the component (B) ) Component is lowered to a predetermined range so that the copolymerization of both components can be lowered.

Further, the refractive index of the plate-like region derived from the component (A) in the louver structure can be increased, and the difference from the refractive index of the plate-shaped region derived from the component (B) can be more easily adjusted to a predetermined value or more.

When R ¹ to R ¹⁰ in the general formula (1) contain any of an alkyl group, an alkoxy group, a halogenated alkyl group, a hydroxyalkyl group and a carboxyalkyl group, the number of carbon atoms in the alkyl moiety is preferably in the range of 1 to 4 Is preferably set to a value within the range.

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.

Accordingly, when R ¹ to R ¹⁰ in the general formula (1) contain any of an alkyl group, an alkoxy group, a halogenated alkyl group, a hydroxyalkyl group and a carboxyalkyl group, the number of carbon atoms in the alkyl moiety is preferably in the range of 1 to 3 More preferably within a range of 1 to 2, and 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.

Further, in the conventional light diffusing 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.

In this respect, a 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 exert a good dependence on the incidence angle even when it does not contain a halogen.

Further, the "good incident angle dependency" means that the distinction between the light diffusion incidence angle region and the non-scattered 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, by setting the position of the substituent represented by the general formula (2) to a position other than R ¹ and R ¹⁰ , it is possible to effectively prevent crystallization by orienting the components (A) It is because.

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

This is because it is possible to coagulate and phase-separate the components (A) and (B) at a fine level in the photo-curing step and to obtain a light diffusion film having a louver structure more efficiently.

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 excessively long, and the polymerization of the component (A) in the polymerization site may be inhibited Because.

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 and 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).

(1) -2 Molecular weight

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

This is because it is presumed that the polymerization rate of the component (A) is made faster and the copolymerization of the component (A) and the component (B) can be more effectively lowered by setting the molecular weight of the component (A) .

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 with the component (B) decreases, and the polymerization rate of the component (A) 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).

(1) -3 Independent 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.

The reason for this is that by such a constitution, it is possible to effectively suppress the irregularity of the refractive index in the plate-like region derived from the component (A), that is, the plate-shaped region with a relatively high refractive index, I can get it.

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

In this case, however, the refractive index in the plate-shaped region derived from the component (A) is relatively high due to the influence of the third component, or the refractive index may be easily deteriorated.

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 has compatibility 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) can be used as the component (A) alone so as to have compatibility with the component (B) .

(1) -4 Refractive index

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

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

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 even the apparent state of the component (B) may become difficult to form.

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.

(1) -5 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 a component (B) which is a polymerizable compound having a relatively low refractive index desirable.

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 presence of the component (A) in 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 still more preferably within a range of 50 to 200 parts by weight with respect to 100 parts by weight of the component (B).

(2) Low refractive index polymerizable compound

(2) -1 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, A (meth) acryloyl group-containing silicone resin, an unsaturated polyester resin, and the like can be given as the (meth) acryloyl group having a (meth) acryloyl group in the side chain. In particular, a urethane (meth) acrylate is 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, urethane (meth) acrylate as 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, , Aromatic polyisocyanates such as 4-xylylene diisocyanate, alicyclic polyisocyanates such as hexamethylene diisocyanate, alicyclic polyisocyanates such as isophorone diisocyanate (IPDI) and hydrogenated diphenylmethane diisocyanate, , An isocyanurate compound, and an adduct that is a reaction product of a low-molecular active hydrogen-containing compound such as ethylene glycol, propylene glycol, neopentyl glycol, trimethylol propane, or castor oil (for example, xylylene diisocyanate type trifunctional And a duct body).

Among the above, alicyclic polyisocyanates are particularly preferable.

This is because, in the case of the alicyclic polyisocyanate, a difference in the reaction rate of each isocyanato group can be easily obtained in relation to the steric hindrance etc. as compared with the aliphatic polyisocyanate.

This prevents the component (B1) from reacting only with the component (B2) or from reacting only the component (B3) with the component (B1) And it is possible to prevent the occurrence of excess by-products.

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 with the component (B) and the component (A) to be obtained is lowered to a predetermined range as compared with the aromatic polyisocyanate, whereby the louver structure can be formed more efficiently.

In addition, when the alicyclic polyisocyanate is used, the refractive index of the obtained component (B) can be made smaller than that of the aromatic polyisocyanate, so that the difference from the refractive index of the component (A) In addition, a louver structure having high uniformity of diffused light in the light diffusion angle region can be formed more efficiently.

Among such 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 such alicyclic diisocyanate, isophorone diisocyanate (IPDI) is particularly preferable.

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 them, polypropylene glycol is particularly preferable.

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

In addition, when polypropylene glycol is used, the component (B) is cured, which is a good soft segment in the cured product, 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 according to 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:

This is because, with such a blending ratio, one isocyanato group of the component (B1) reacts and bonds to two hydroxyl groups of the component (B2), and the two (B1) (Meth) acrylate in which the hydroxyl group of the component (B3) is reacted and bonded to the other isocyanato group can be efficiently synthesized.

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.

(2) -2 Weight average molecular weight

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

The reason for this is that by setting the weight average molecular weight of the component (B) to a predetermined range, it is possible to cause a predetermined difference in polymerization rate between the component (A) and the component (B) 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).

(2) -3 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) Is preferably used.

That is, when a plurality of the component (B) is used, the refractive index in the plate-shaped 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 from the plate-shaped area may become uneven or excessively decrease.

(2) -4 refractive index

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

This is because by setting the refractive index of the component (B) to a value within this range, the difference between the refractive indexes of the plate-shaped region derived from the component (A) and the plate-shaped region derived from the component (B) , A light diffusion film having a louver structure can be obtained more efficiently.

That is, when the refractive index of the component (B) is less than 1.4, the difference with the refractive index of the component (A) becomes large, but the compatibility with the component (A) is extremely deteriorated and the louver structure can not be formed This is because of concerns. 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 the desired incidence 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.

This is because 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.

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 indexes 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 in the range of 0.05 to 0.5, and more preferably in the 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.

(2) -5 content

The content of the component (B) in the composition for a light diffusion 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 diffusion film.

This is because when the content of the component (B) is less than 10% by weight, the presence of the component (B) in 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 be 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 be 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- .

(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.

The reason for this is that by containing a photopolymerization initiator, a louver structure can be efficiently formed when an active energy ray is irradiated to a composition for a light diffusion film.

Here, the photopolymerization initiator means a compound which 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. May be used.

The content of the photopolymerization initiator is preferably within a range of 0.2 to 20 parts by weight, more preferably within a range of 0.5 to 15 parts by weight, based on 100 parts by weight of the total of the components (A) and (B) Value, more preferably within a range of 1 to 10 parts by weight.

(4) Other additives

Additives other than the above-mentioned compounds may be added within the range not impairing the effect of the present invention.

Examples of such an additive include an antioxidant, an ultraviolet absorber, an antistatic agent, a polymerization accelerator, a polymerization inhibitor, an infrared absorber, a plasticizer, a diluting solvent, and a leveling agent.

The content of such an additive is generally 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 of the components (A) and (B) Value, more preferably 0.05 to 2 parts by weight.

4. Process (b): The first coating process

The step (b) is a step of applying the prepared composition for a light-diffusing film to the process sheet 2 to form the first applied layer 1a, as shown in Fig. 4 (a).

As the process sheet, any of plastic film and 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 gloss paper, coated paper, and laminated paper.

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 such plastic films, polyester films, polyolefin films and polyimide films are preferably used.

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.

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

Examples of the method for 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 .

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, and 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.

5. Process (c): The first active energy irradiation process

4 (b), the first coated layer 1a is moved in the moving direction E while moving the linearly polarized light source 125a along the moving direction E as shown in Fig. 4 (b) , The first active energy ray irradiation (150a) is performed to form the first louver structure (13a).

More specifically, for example, as shown in Fig. 5 (a), an ultraviolet irradiator 120 (for example, a commercially available product) in which a cold mirror 122 for light-converging is provided on a linear ultraviolet lamp 125a, The heat ray cut filter 121 and the light shielding plates 123 (123a and 123b) are disposed in a glass substrate (for example, a glass substrate made by IGraphics Co., Ltd., ECS-4011GX etc.) to take out the active energy ray 150a, And the first coated layer 1a formed on the process sheet 2 is irradiated.

6 (a), 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 movement E of the first coated layer 1a 2 formed by the imaginary line E 'according to the angle? Is set to a value within a 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, not only the direction in which the incident light is arranged in the longitudinal direction but also the direction perpendicular to the longitudinal 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 value of? 2 is less than 10, the light diffusion characteristic in the direction along the longitudinal direction of the film is excessively lowered in general, depending on the arrangement angle of the linear light source in the step (e) , The diffusion area of the incident light may become excessively small. On the other hand, when the value of? 2 exceeds 80 °, the light diffusion characteristic in a direction orthogonal to the longitudinal direction of the film is excessively large, depending on the arrangement angle of the linear light sources in the step (e) And the diffusion area of the incident light may become excessively small.

Therefore, when viewed from above the film, the acute angle &thetas; 2 between the long axis direction of the linear light source in the first active energy ray irradiation and the imaginary line in the moving direction of the first coated layer is in the range of 35 to 55 DEG More preferably in a range of 40 to 50 degrees, and more preferably in a range of 44 to 46 degrees.

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

The irradiation angle of the active energy ray is preferably in the range of -80 to -60 degrees as shown in Fig. 5 (b), when the angle of the normal to the surface of the first coated layer 1a is 0 deg. 80 [deg.].

This is because if the irradiation angle is out of 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.

It is preferable that the irradiation angle 6 has a width (irradiation angle width) 6 'of 1 to 80 degrees.

The reason for this is that when the irradiation angle width 6 'is less than 1 DEG, the moving speed of the coating layer must be excessively lowered, thereby lowering the manufacturing efficiency. On the other hand, when the irradiation angle width? 6 'exceeds 80 °, it is difficult to form the louver structure because the irradiation light is excessively dispersed.

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.

In addition, when the irradiation angle width 6 'is provided, the angle of the intermediate position is exactly the irradiation angle 6.

It is preferable that the first active energy ray irradiation is performed through a light shielding plate having an active energy ray transmitting portion in a long groove and the longitudinal direction of the active energy ray transmitting portion is parallel to the longitudinal direction of the linear light source.

Further, the active energy ray transmitting portion may be any type as long as it is transparent to the active energy ray.

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

Concretely, as shown in Fig. 7, a gap (active energy ray transmitting portion) having a long groove formed by the two light blocking plates 123 (123a, 123b) is interposed, It is preferable that the direction is parallel to the longitudinal direction of the linear light source 125a.

By arranging the shading plate in this manner, the irradiation angle 6 of the active energy ray 150a shown in Fig. 5 (a) is adjusted to a value within a predetermined range, and each position on the surface of the first coated layer 1a It is possible to effectively suppress the irradiation of the active energy ray 150a from the linear light source 125a at an excessively different angle.

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 property of the obtained long-axis light diffusion film can be made uniform.

The peak illuminance at 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 is less than 0.1 mW / cm 2, it may be difficult to clearly form the first 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, and 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.

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 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, 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 speed of the first coated layer 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 velocity of the first coating layer exceeds 10 m / min, the curing of the first coating layer, in other words, the angle of incidence of the active energy ray with respect to the first coating 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.

The reason for this is that by laminating the 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 the oxygen, 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 coated layer, it is preferable to use random light in any traveling direction, not parallel light.

6. Process (d): The second coating process

4 (c), the composition for a 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 the second coated layer 1b are formed on the surface of the layered product 1c.

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-diffusing film, the reflection at the interface between the coating layer 1a 'and the coating layer 1b' can be suppressed and the adhesion can also be improved.

Examples of the method of 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, and gravure coating method (B) described above, or the like.

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 within this range.

That is, 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, and 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.

7. Process (e): The second activation energy ray irradiation process

4 (d), 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 the 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. When viewed from above the film, an acute angle &thetas; 1 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, To a value within a range of 10 to 90 degrees.

That is, by defining the relation 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 extending direction of the second louver structure It is possible to efficiently produce an elongated light diffusion film formed by crossing the extending direction of the plate-shaped region at a predetermined angle.

Accordingly, 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 in which the diffusion area of the incident light is effectively widened.

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 orthogonal to its longitudinal direction, without connecting a plurality of light diffusion films as in the conventional art have.

That is, when the acute angle [theta] 1 shown in FIG. 6 (b) is less than 10 degrees, the diffusion area of the incident light may be excessively small.

Therefore, when viewed from above the film, an acute angle &thetas; 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 80 to 90 More preferably in the range of 85 to 90 degrees, and more preferably in the range of 89 to 90 degrees.

6 (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 coating 3 formed by the virtual line E 'along the moving direction E of the layered product 1c composed of the layer 1a' and the second coated layer 1b is set to a value within a range of 10 to 80 ° .

The reason for this is that by defining the arrangement angles of the linear light sources in this way, it is possible to reduce the incident angle of 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 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 characteristic in the direction along the longitudinal direction of the film is excessively lowered, generally depending on the arrangement angle of the linear light sources in the above-described step (c) , The diffusion area of the incident light may become excessively small. On the other hand, when the angle θ3 exceeds 80 °, the light diffusion characteristics in the direction orthogonal to the longitudinal direction of the film are excessively large, 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 become 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 imaginary line in the moving direction of the laminate composed of the first coating layer and the second coating layer 3) is more preferably in the range of 35 to 55 °, more preferably in the range of 40 to 50 °, and still more preferably in the range of 44 to 46 °.

It is preferable that the gap between the linear light source 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. 5 (a) to 5 (b).

As shown in Fig. 6 (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 Symmetrical with respect to the imaginary line E '', which is perpendicular to the moving direction E of the laminate composed of the first coated layer 1a 'and the second coated layer 1b, desirable.

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

Specifically, in the case where? 2 = 45 ° and? 3 = 45 °, or in the case where each is a peripheral value, the linear light sources are arranged so as to be in line symmetry, The spreading in the left-right direction and the spreading in the up-down direction 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 arrangement angle of the linear light sources (the extending direction of the plate-shaped area) and the diffusion area of incident light will be described with reference to Figs. 8 (a) to 8 (e).

8A to 8E show the first louver structure 13a on the left side and the light diffusion state 50 'incident on the first louver structure 13a and the second louver structure 13b on the right side, And the diffusion state 51 'of the diffusion light by the first louver structure 13a.

8A 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 incident light is sufficiently widened (51 ').

On the other hand, FIG. 8B shows the diffusion state of incident light in the case of? 1 = 60 °,? 2 = 30 °, and? 3 = 30 °. In comparison with the case of FIG. 8 (a) 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').

8 (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. 8 (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. 8 (d) shows the diffusion state of incident light in the case of? 1 = 30,? 2 = 15, and? 3 = 15, 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').

8 (e) shows the diffused state of the incident light in the case of? 1 = 30,? 2 = 75, and? 3 = 75. Compared with the case of FIG. 8 (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. 9 (a) to 9 (e) show photographs of the diffused light corresponding to Figs. 8 (a) to 8 (e).

As shown in Fig. 7, 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 a long groove formed by two shading plates, It is preferable that the longitudinal direction of the gap is 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 is 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, and 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, for the same reason as in the first active energy ray irradiation, the moving speed of the laminate composed of the first coating layer and the second coating 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 performed in succession to the steps (b) to (c) using one conveyor, (D) to (e) may be carried out by collecting the first coated layer formed thereon in the form of a roll and placing it on a separate conveyor.

Therefore, in the case of the former, the linear light source in the step (c) and the linear light source in the step (e) are separately disposed (in the latter case, May be used.

8. Light diffusion film

Hereinafter, the light diffusion film obtained by the production method of the present invention will be described.

(1) First louver structure

(1) -1 Refractive index

In the first louver structure, it is preferable that the difference in refractive index 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- .

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 to further improve the incidence angle dependence derived from the first louver structure.

More specifically, when the difference in the refractive indexes is less than 0.01, the angle of incidence of the incident light in the first louver structure becomes narrower, so that the incidence angle dependence may excessively decrease.

Therefore, it is more preferable that the difference in refractive index between the plate-shaped regions having different refractive indexes in the first louver structure is more preferably 0.03 or more, and more preferably 0.05 or more.

Further, 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 is, the better, but from the viewpoint of selecting the material capable of forming the first louver structure, the upper limit can be 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 in accordance with, for example, 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 when 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-shaped 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.

(1) -2 width

10 (a), the widths S1 and S2 of the high refractive index plate-shaped region 12 and the low refractive index plate-shaped region 14 having different refractive indexes are set to 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 and the incident angle dependence derived from the first louver structure is improved more effectively I can do it.

That is, when the width of such a plate-shaped area is less than 0.1 탆, it may be difficult to exhibit 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 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 film cross section with an optical digital microscope.

(1) -3 inclination angle

10 (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 arranged at regular angles (? a).

The reason for this is that the incidence angle dependence attributable to the first louver structure can be further improved by stably reflecting the incident light in the first louver structure by making each inclination angle? A constant in the plateau region .

In addition,? A is the plateau area when the angle of the normal to the film surface measured at the end face when the film is cut at the plane perpendicular to the first louver structure extending in any one direction along the film plane is 0 (Deg.

More specifically, as shown in Fig. 10 (a), the angle of the narrower side of the angle formed by the normal of the top surface of the first louver structure and the top of the plate-shaped area. 10 (a), the inclination angle when the plate-shaped region is tilted to the right is referred to as a reference, and the inclination angle when the plate-shaped region is tilted to the left is indicated as minus.

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

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.

Such a curved louver structure can be considered to be obtained by slowing the polymerization reaction speed by ultraviolet rays in the thickness direction of the coating film.

Specifically, it can be formed by suppressing the illuminance of ultraviolet rays emitted from the linear light source and moving the coated film in the irradiated state at low speed.

(1) -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. 10A and 10B is a value within a range of 50 to 500 mu m .

The reason for this is that by setting the thickness of the first louver structure to a value within this range, the length of the first louver structure along the film thickness direction can be stably secured, the incident light can be more stably reflected in the first louver structure, It is possible to further improve the uniformity of the intensity of the diffused light within the light diffusion angle range derived from the one louver structure.

That is, when the thickness (L1) of the first louver structure is less than 50 占 퐉, the length of the first louver structure is insufficient, and the incident light that goes straight in the first louver structure increases, It is sometimes difficult to obtain the uniformity of the intensity of the diffused light in the light source. 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 may be difficult to form a 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.

(1) -5 extension direction

Further, when viewed from above the film, it is preferable that the acute angle formed by the extending direction of the plate-shaped region in the first louver structure and the longitudinal direction of the film is 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 this range, the incident light can be directed not only in the direction along its longitudinal direction, This is because the diffusion area of the incident light can be widened effectively by diffusing light also in the direction orthogonal to the longitudinal direction.

That is, when the acute angle is less than 10, the light diffusion characteristic in the direction along the longitudinal direction of the film is excessively lowered, though depending on the extending direction of the plateau region in the second louver structure, This is because the diffusion area of the incident light may be excessively small. On the other hand, if the acute angle exceeds 80 DEG, the light diffusion property in the direction orthogonal to the longitudinal direction of the film is deteriorated excessively, in spite of the extending direction of the plateau region in the second louver structure This is because the diffusion area of the incident light may be excessively small.

Therefore, when viewed from above the film, it is more preferable that the acute angle formed by the extending direction of the plate-shaped region in the first louver structure and the longitudinal direction of the film is within a range of 35 to 55 DEG, Deg.], More preferably in the range of 44 to 46 [deg.].

(2) Second louver structure

Since the configuration of the second louver structure is basically the same as that of the first louver structure, a description thereof will be omitted.

(3) 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, the incident light which goes straight in the louver structure increases, It is sometimes difficult to obtain 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 or impossible to form.

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.

Further, in the film thickness direction of the light-diffusing 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.

(4) Shape of film

The shape of the light-diffusing film obtained by the production method of the present invention is characterized by being a long-length phase.

More specifically, as shown in Fig. 11 (a), the length L2 of the light diffusion film 10 in the short side direction is preferably set to a value within a range of 0.1 to 3 m, more preferably within a range of 0.5 to 2 m Value is more preferable.

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

That is, in the manufacturing method of the present invention, it is possible to continuously manufacture a light diffusion film capable of optically diffusing incident light not only in a direction along its longitudinal direction but also in a direction orthogonal to its longitudinal direction.

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.

This is because the film has such a shape that it is an elongated image capable of diffusing incident light not only in the direction along its longitudinal direction but also in a direction orthogonal to its longitudinal direction, I can get it.

Also, as shown in Fig. 11 (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 roll form, it is possible to obtain a large-sized light diffusion film which is a long film which can diffuse the 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.

More specifically, in the case of a roll, the workability is improved as compared with the case of being produced by dropping to a sheet.

Further, in the case of a roll-like shape, even when the size of a display or the like to which a film is to be applied is over a wide range, a chip can be cut to a required size later.

Further, if it is roll-like, it can be bonded to other film and roll-to-roll in the next step, so that the productivity can be improved as compared with the case where the sheet-to-sheet is employed.

(5) Combination of extension direction

In the light diffusion film obtained by the manufacturing method of the present invention, when viewed from above the film, the extending direction of the plate-like 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.

The reason for this is that by structuring such a structure, 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.

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 more preferably a value within a range of 89 to 90 DEG.

(6) 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 acrylic, silicone, urethane, rubber can be used.

[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 mol of isophorone diisocyanate (IPDI) as a component (B3) were added to 1 mol 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 a 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 equivalent measured by gel permeation chromatography (GPC) under the following conditions.

GPC measurement apparatus: HLC-8020 manufactured by Tosoh Corporation

· GPC column: made by Toso Co., Ltd. (hereinafter referred to as passing order)

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 (meth) acrylate 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.

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, manufactured by Atago Co.) And 1.46.

3. First coating step

Then, the obtained 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 Igraphics Co., Ltd.) to which a cold mirror for condensing light was attached was prepared in a high-pressure mercury lamp of a line shown in Fig. 5 (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 heat-ray cut filter frame 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, (? 6 in FIG. 5 (b)) of the direct ultraviolet light from the light source is 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 the reflected light from the shading plate or the like from becoming stray light inside the irradiation device and affecting the photo-curing of the first coated layer, two shading plates are provided near the conveyor as shown in Fig. 7, And only ultraviolet light emitted directly from the light source was irradiated onto the first coated layer.

More specifically, as shown in Fig. 7, a gap (gap width: 35 cm) in the form of a long groove formed by two shading plates is formed so that the longitudinal direction of the gap in the long groove is aligned in the long axis direction of the linear light source It was installed so as to be in a parallel direction.

Subsequently, the first coated layer was irradiated with ultraviolet rays while moving the first coated layer in the rightward direction at a speed of 1.0 m / min by a conveyor to measure the length in the longitudinal direction (moving direction of the first coated layer) A first coated layer having a first louver structure of a long length having a length of 1.25 m and a film thickness of 165 mu m was obtained.

Subsequently, in order to ensure reliable curing, a release film (SP-PET382050, manufactured by LINTEC CORPORATION; SP-PET382050) having a thickness of 38 mu m and having a thickness of 38 mu m and an active energy ray- A center line average roughness at the surface of 0.01 mu m, a haze value of 1.80%, a phase clarity of 425, and a transmittance of 84.3% at a wavelength of 360 nm).

Then, scattering 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 peak illuminance and the accumulated light amount were measured by placing a UV meter (UV-IR integrated light meter UVPF-A1 manufactured by Igraphics Co., Ltd.) equipped with a photodetector 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 (TECLOCK 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 same composition for a light-diffusing film as used for forming the first coating layer was applied to the exposed surface of the first coating layer on which the obtained first long luer structure was formed to form a second coating layer .

6. Second active energy irradiation process

Then, when viewed from above the film, an acute angle &thetas; 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 90 DEG Except that the ultraviolet irradiator is provided so as to irradiate the ultraviolet light, ultraviolet light is irradiated to form a long-lived light diffusion film having a first louver structure and a second louver structure and having a film thickness of 330 mu m .

Further, when viewed from above the film, the acute angle [theta] 3 formed by the imaginary line in the longitudinal direction of the linear light source and the moving direction of the laminate composed of 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. 12, 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 It was confirmed that the acute angle was 90 °.

It was also 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 °.

It was also 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 °.

13 (a) is a photograph of a cross section taken along a plane perpendicular to the longitudinal direction of the film, and FIG. 13 Are shown in Fig. 13 (b).

Further, the light diffusion film was cut using a razor, and photographing of the cross section was performed using an optical microscope (reflection observation).

7. Measurement

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

Subsequently, spectrum charts of the diffused light in the direction perpendicular to the longitudinal direction of the film and in the direction parallel to the longitudinal direction of the film were obtained by using a goniometric colorimeter (VC-2 made by Suzuki Kagaku Co., Ltd.).

That is, as shown in Fig. 14 (a), when the horizontal axis represents the light diffusion angle (?) In the diffused light diffused by the light diffusion film and the relative intensity (- I got a chart.

Here, the spectrum chart A shown in Fig. 14 (a) corresponds to the diffused light in the direction perpendicular to the longitudinal direction of the film, and the spectrum chart B corresponds to the diffused light in the direction parallel to the longitudinal direction of the film .

Further, a photograph of the diffused light when viewed from the Z direction in Fig. 12 was obtained by using a conoscope (manufactured by autronic-MELCHERS GmbH) as shown in Fig. 14 (b).

The results shown in Figs. 14 (a) and 14 (b) are consistent with the light diffusion characteristics predicted from the film having the internal structure shown in Fig.

[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 irradiation step were not performed.

As shown in Fig. 15, 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 was 45 °.

Fig. 16 (a) is a photograph of a section obtained by cutting the obtained light diffusion film at a plane orthogonal to the longitudinal direction of the film, and Fig. 16 Are shown in Fig. 16 (b).

Further, as in Example 1, the light diffusion state was measured from the lower side of the obtained light diffusion film when light was incident from the direction orthogonal to the film surface with respect to the film.

A spectrum chart of the obtained diffused light is shown in Fig. 17 (a), and a photograph of the diffused light when viewed from the Z direction in Fig. 15 is shown in Fig. 17 (b).

17 (a) shows a spectrum chart in the direction along the diffusion direction (long axis direction) of diffused light shown in Fig. 17 (b).

The results shown in Figs. 17 (a) to 17 (b) were consistent with the light diffusion characteristics predicted from the film having the internal structure shown in Fig.

[Comparative Example 2]

In Comparative Example 2, in the first active energy ray irradiation step, when viewed from above the film, the acute angle? 2 formed by the virtual line in the longitudinal direction of the linear light source and the moving direction of the first coated layer was 90 degrees , The first coating layer was subjected to a first activation energy beam irradiation step as in Example 1 to obtain a first coating layer (one having a first louver structure formed therein).

As shown in Fig. 18 (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 its longitudinal direction 90 °.

Subsequently, as shown in Fig. 18 (b), the elongated first coating layer formed with the obtained first louver structure was cut every 1.1 m in the longitudinal direction to form a plurality of spool-like first coating layers did.

Next, as shown in Fig. 18 (c), a plurality of spool-shaped first coating layers formed with the obtained first louver structure were rotated 90 ° in the plane, and then side by side, So that they were connected to each other.

Thus, as shown in Fig. 18 (c), when viewed from the upper side of the film, the elongated direction of the plateau region in the louver structure and the elongated direction form a long louver A first coated layer (one having the first louver structure formed therein) was obtained.

18 (c), a long coat layer shown in Fig. 18 (a) was applied to the elongated first coat layer formed with the obtained first louver structure through an acrylic-based transparent pressure-sensitive adhesive layer having a thickness of 25 m As a second coating layer of a elongated phase having a second louver structure, to obtain a light diffusion film.

As shown in Fig. 19, the resulting light-diffusing film has a structure in which 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 area It was confirmed that the acute angle was 90 °.

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

Fig. 20 (a) is a photograph of a section obtained by cutting the obtained light diffusion film at a plane orthogonal to the longitudinal direction of the film, and Fig. 20 Are shown in Fig. 20 (b).

Further, as in Example 1, the light diffusion state was measured from the lower side of the obtained light diffusion film when light was incident from the direction orthogonal to the film surface with respect to the film.

Fig. 21 (a) shows a spectrum chart of the diffused light obtained by introducing light into the jointless portion, and Fig. 21 (b) shows a photograph of the diffused light when viewed from the Z direction in Fig.

The results shown in Figs. 21 (a) to 21 (b) are consistent with the light diffusion characteristics predicted from the film having the internal structure shown in Fig.

However, in the case where light is incident on the joint portion, it has been confirmed that the light diffusing property tends to become uneven due to the joint portion of the film as shown in Figs. 22 (a) to (b).

As described above, according to the present invention, in a predetermined manufacturing method including two active energy ray irradiation processes using a linear light source, the arrangement angle of each linear light source in the two active energy ray irradiation processes The light diffusion of the incident light is effectively performed not only in the direction along the longitudinal direction but also in the direction orthogonal to the longitudinal direction thereof by effectively defining the longitudinal light diffusion film effectively spreading the diffusion area of the incident light .

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

1a: first coating layer
1a ': a first coating layer formed with a first louver structure
1b: second coating layer
1c: a laminate comprising a first coating layer and a second coating layer
2: Process sheet
10: Light diffusion film
12: a plate-like region having a relatively high refractive index
13: Louver structure
13a: First louver structure
13b: second louver structure
13 ': boundary surface of the louver structure
14: Plate region having a relatively low refractive index
20: Light diffusion film obtained by the production method of the present invention
50 ': Light diffusion state
51 ': diffusion state of diffused light
120: ultraviolet irradiator
121: Heat cut filter
123: Shading plate
125: linear light source
150: active energy ray

Claims (8)

A first louver structure and a second louver structure formed by alternately arranging a plurality of plate-shaped regions having different refractive indexes in an arbitrary one direction along the film plane in parallel from the downward direction in the film thickness direction, As a method for producing a diffusion film,
A process for producing a light-diffusing film, which comprises 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 the composition for a light diffusion film to a process sheet to form a first coated layer
(c) When the first coated layer is viewed from above the film using a linear light source while moving the first coated layer, the direction of the long axis of the linear light source and the moving direction of the first coated layer The first active energy ray irradiation is performed so that the acute angle [theta] 2 formed by the imaginary line along the imaginary line is within a range of 10 to 80 degrees, thereby forming the first louver structure
(d) applying the composition for light diffusion film to the first coating layer on which the first louver structure is formed, to form a laminate comprising the first coating layer and the second coating layer
(e) when viewed from above the film, using the linear light source while moving the laminate composed of the first coated layer and the second coated layer with respect to the second coated layer, The second active energy ray irradiation is performed so that the acute angle? 3 formed by the imaginary line along the moving direction of the laminate composed of the first coated layer and the second coated layer is within the range of 10 to 80 degrees, Wherein when viewed from above the film, an acute angle formed by the long axis direction of the linear light source in the first active energy ray irradiation and the long axis direction of the linear light source in the second active energy ray irradiation, (? 1) within a range of 10 to 90 degrees delete The method according to claim 1,
Wherein, in the step (e), when viewed from above the film, the long axis direction of the linear light source in the first active energy ray irradiation and the long axis direction of the linear light source in the second active energy ray irradiation, Wherein a line perpendicular to the moving direction of the laminate composed of the first coated layer and the second coated layer is line-symmetrical. The method according to claim 1,
In the steps (c) and (e), the first active energy ray irradiation and the second active energy ray irradiation are performed by interposing a light shielding plate having an active energy ray transmitting portion in a long groove, Wherein the longitudinal direction of the transmissive portion is a direction parallel to the major axis direction of the linear light source. The method according to claim 1,
In the step (c), the peak illuminance on the surface of the first coated layer in the first active energy ray irradiation is set to a value within a range of 0.1 to 50 mW / cm 2, Wherein the total amount of light on the surface is set to a value within a range of 5 to 300 mJ / cm < 2 >. The method according to claim 1,
Wherein in the step (e), the peak illuminance at the surface of the second coated layer in the second active energy ray irradiation is set to a value within a range of 0.1 to 50 mW / cm 2, Wherein the total amount of light on the surface is set to a value within a range of 5 to 300 mJ / cm < 2 >. The method according to claim 1,
(B), the film thickness of the first coated layer is set to a value within a range of 80 to 700 m, and in the step (d), the thickness of the second coated layer is set to 80 to 700 m Of the light diffusing film. The method according to claim 1,
The moving speed of the first coated layer in the step (c) and the moving speed of the laminated body composed of the first coated layer and the second coated layer in the step (e) are each in the range of 0.1 to 10 m / min Of the light diffusing film.

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