KR20120067940A - Light diffusion film and producing method for the same - Google Patents

Abstract

PURPOSE: A light diffusion film and a manufacturing method thereof are provided to steadily reflect incident light by stably obtaining the length of a louver structure according to the direction of a film thickness. CONSTITUTION: A first structure domain(10) anisotropically diffuses incident light. A second structure domain isotropically diffuses the incident light. The first structure domain is a louver structure domain. The louver structure domain parallelly arranges plate shape domains in which a refractive index is different according to a film plane direction. The second fabric domain is a columnar structure domain.

Description

Manufacturing method of light diffusing film and light diffusing film {LIGHT DIFFUSION FILM AND PRODUCING METHOD FOR THE SAME}

This invention relates to the manufacturing method of a light-diffusion film and a light-diffusion film. In particular, by including a louver structure region for anisotropically diffusing the incident light and a column structure region for isotropically diffusing the incident light, the light diffusion incident angle region has a good incidence angle dependence in the transmission and diffusion of light. A method for producing a wide light diffusing film and a light diffusing film.

Conventionally, in a liquid crystal display device, it is possible to recognize a predetermined image by using light emitted from a light source (internal light source) provided inside the device.

However, in recent years, with the spread of mobile phones, in-vehicle televisions, and the like, opportunities for viewing liquid crystal display screens are increasing outdoors. As a result, the light intensity from the internal light source lags behind the external light, and the predetermined screens are removed. The problem that it becomes difficult to recognize has arisen.

In addition, in mobile applications such as cellular phones, since the power consumption by the internal light source of the liquid crystal display device has a large ratio with respect to the total power consumption, when the internal light source is extensively used, There is a problem that the duration becomes short.

Thus, in order to solve these problems, a reflective liquid crystal display device using external light as part of a light source has been developed.

In such a reflective liquid crystal display device, since external light is used as a part of the light source, the stronger the external light, the clearer the image can be recognized, and the power consumption of the internal light source can be effectively suppressed.

Further, in such a reflective liquid crystal display device, in order to efficiently transmit external light and absorb the light into the inside of the liquid crystal display device, and to effectively use the external light as a part of the light source, the light is diffused efficiently. It is proposed to have a light diffusing film for the following (for example, refer to Patent Document 1).

More specifically, in Patent Document 1, as shown in FIGS. 23A to 23B, a liquid crystal cell in which a liquid crystal layer 1105 is sandwiched between an upper substrate 1103 and a lower substrate 1107. And a light reflection plate 1110 provided on the lower substrate 1107 side, and a light control plate (light diffusion film) 1108 provided between the liquid crystal layer 1105 and the light reflection plate 1110. ) Is disclosed.

A light control plate 1108 is provided for selectively scattering light incident at a predetermined angle and transmitting light incident at an angle other than the predetermined angle. The light control plate 1108 is incident at a predetermined angle. The scattering axis direction 1121, which projects the direction of selectively scattering light onto the surface of the light control panel 1108, is disposed in the liquid crystal cell such that the direction of the scattering axis direction 1121 is almost 6 o'clock from the inner surface of the liquid crystal cell.

Here, as a light-diffusion film used for a reflection type liquid crystal display device, the specific photocurable composition is irradiated with an active energy ray using a linear light source, and has a high refractive index plate shape in the film plane direction. ) And a light-diffusion film in which a louver structure region is formed in a film by arranging a region and a low refractive index plate-shaped region in parallel with each other (for example, see Patent Documents 2 to 3).

That is, Patent Document 2 obtains a film-like composition containing a plurality of compounds having a polymerizable carbon-carbon double bond by irradiating ultraviolet rays from a specific direction, curing the composition, and selectively scattering only incident light in a specific angle range. In the light control film (light diffusing film), at least one compound contained in the composition is a compound having a plurality of aromatic rings and one polymerizable carbon-carbon double bond in a molecule. Is disclosed.

Patent Literature 3 also discloses a fluorene-based compound (A) having a polymerizable carbon-carbon double bond in a molecule, a cationically polymerizable compound (B) having a different refractive index from the fluorene-based compound (A), and photocationic polymerization. Disclosed are a photocurable composition comprising an initiator (C) and a light control film formed by curing the same.

On the other hand, as another type of light-diffusion film used for the reflective liquid crystal device, a specific photocurable composition is irradiated with active energy rays as parallel light on the entire surface, and thus the media and the media in the medium along the film thickness direction of the film. The light-diffusion film which forms the column structure area | region which formed the several columnar object in which refractive index differs is disclosed (for example, refer patent documents 4-6).

That is, Patent Document 4 provides a composition containing a photocurable compound on a sheet, irradiates parallel light to the sheet from a predetermined direction P to cure the composition, and extends the sheet in parallel with the direction P inside the sheet. As a manufacturing method of a diffusion medium (light-diffusion film) which forms the aggregate of several rod-shaped hardened regions which exist, the normal thing arrange | positioned in parallel with the direction P between a linear light source and a sheet | seat Disclosed is a method for producing a diffusion medium, which comprises intersecting a set of light and irradiating light through the ordinary material.

In addition, in Citation 5, the linear light source is disposed so as to face the photocurable resin composition film so as to be spaced apart from each other, and at least one of the photocurable resin composition film and the linear light source is irradiated to irradiate light from the linear light source to cure the photocurable resin composition film. As a manufacturing apparatus which forms a light control film (light-diffusion film), the axial direction and the moving direction of a linear light source cross | intersect, and the several sheet-like light-shielding member which opposes each other is a photocurable resin composition film | membrane. Between the light source and the linear light source at a predetermined interval in a direction substantially perpendicular to the moving direction, and on one side of the light-shielding member that faces the photocurable resin composition film so as to be in the same direction as the moving direction, respectively. An apparatus for producing a light control film is disclosed.

Further, Patent Document 6 discloses that a curved surface facing upwards becomes a light absorbing surface, and a downwardly inclined surface covers a Fresnel surface of a linear Fresnel member whose reflection surface is a reflection surface, and the incident light larger than a predetermined angle is disposed. Silver is provided with the diffusion layer (diffusion film) which has the diffusion property which is not diffused, The diffusion layer irradiated parallel light through the photomask which has a light passing band and a light nonpassing band from a predetermined direction to the photocurable resin composition, and was irradiated The 1st light irradiation process which hardens a site | part in an incomplete hardened state, a photo mask is taken out, and parallel light with a substantially constant light intensity distribution is further irradiated to a photocurable composition, and the hardening of a photocurable composition is completed. It is produced by the second light irradiation step, and extends in the film in the direction of irradiation of parallel light in the matrix composed of the photocurable composition and the matrix. Disclosed is a reflective projection screen comprising a phase separation structure having a plurality of columnar structures having different refractive indices from the oriented matrix.

Japanese Patent No. 3480260 (claims, drawings, etc.) Japanese Patent Laid-Open No. 2006-350290 (claims, drawings, etc.) Japanese Patent Laid-Open No. 2008-239757 (claims, drawings, etc.) Japanese Patent No. 4095573 (claims, drawings, etc.) Japanese Patent Laid-Open No. 2009-173018 (claims, drawings, etc.) Japanese Patent Laid-Open No. 2008-256930 (claims, drawings, etc.)

However, in the light-diffusion film having the louver structure region disclosed in Patent Literatures 1 to 3, the incident angle region (hereinafter sometimes referred to as a light diffusion incident angle region) of the light-diffusing incident light becomes narrow or further diffuses. It has been found that the spread angle of the light also narrows.

In addition, the light diffusing film having the columnar structure region disclosed in Patent Documents 4 to 5 has a tendency to be uneven in reflection of light in the film, as compared to the light diffusing film having the louver structure region. The unevenness of the diffusion characteristics caused by this is so large that it is difficult to exhibit a good incidence angle dependency.

Therefore, in view of the above circumstances, the present inventors have made diligent efforts to provide a good incidence angle dependency by providing a louver structure region for anisotropically diffusing incident light and a column structure region for isotropically diffusing incident light in the film. In addition, it was found that a light-diffusion film having a wide light-diffusion incident angle region can be obtained, and completed the present invention.

That is, an object of the present invention is to provide a light diffusion film having a wide light diffusing incident angle region and a method of manufacturing the same while having good incidence angle dependence in light transmission and diffusion.

According to the present invention, in a light diffusing film having a first structural region for anisotropically diffusing incident light and a second structural region for isotropically diffusing incident light, the first structural region has a plurality of plate shapes having different refractive indices. The louver structure region formed by arranging regions parallel to each other along the film plane direction, and the second structural region is a column structure region formed by standing up a plurality of columnar objects having a refractive index different from that of the media in the media. A diffusion film is provided, which can solve the above problem.

That is, in the light-diffusion film of the present invention, a louver structure region as a first structural region for anisotropically diffusing incident light and a column structure region as a second structural region for isotropically diffusing incident light are provided in the film. .

Therefore, by overlapping the incident angle dependence of each structural region, the unevenness of the diffusion characteristic can be suppressed, and the favorable incident angle dependency can be obtained, and the spreading angle of the diffused light can be effectively widened.

In addition, by varying the incident angle dependency of each structural region, the light diffusion incident angle region can be effectively and easily widened.

In addition, in this invention, a "film surface direction" shall mean the x-y planar direction in the case where the film thickness direction is made into the y-axis.

In addition, in this invention, a "light-diffusion incident angle area | region" means the angle range of incident light corresponding to outgoing diffused light, when the angle of incident light from a point light source is changed with respect to an anisotropic light-diffusion film. do. The detail of this light-diffusion incident angle area | region is mentioned later.

In addition, "good incidence angle dependence" means that the distinction between the incident angle region (light diffusion incident angle region) with respect to the film where light diffusion of incident light occurs and the other incident angle region where light diffusion does not occur clearly It means to be controlled.

Furthermore, in the present invention, "anisotropy" means that the shape of spreading of the diffused light has anisotropy, and "isotropic" means that the shape of spreading of the diffused light has isotropy. do.

Moreover, in constructing the light-diffusion film of this invention, in the 1st structural region, while setting the width | variety of the plate-shaped area | region with which refractive index differs, it is a value within the range of 0.1-15 micrometers, respectively, and the said plate-shaped area | region is film thickness. It is preferable to arrange | position in parallel with a fixed inclination angle with respect to a direction.

By configuring in this way, incident light can be reflected more stably in the louver structure area | region as a 1st structure area | region, and the incident angle dependency derived from a 1st structure area | region, and the spreading angle of diffused light can be improved further.

Moreover, in constructing the light-diffusion film of this invention, in the 1st structural area | region, of the (meth) acrylic acid ester in which the main component of the plate-shaped area | region with a high refractive index contains a some aromatic ring in the plate-shaped area | region which differs in refractive index, It is a polymer, and it is preferable that the main component of the plate-shaped area | region with low refractive index is a polymer of urethane (meth) acrylate.

By such a configuration, not only the louver structure as the first structural region can be formed efficiently, but also the incident angle dependence and the spreading angle of the diffused light derived from the first structural region can be further improved.

Moreover, in forming the light-diffusion film of this invention, it is preferable to make thickness of a 1st structural area into the value within the range of 5-495 micrometers.

By configuring in this way, the length of the louver structure along the film thickness direction is ensured stably, the incident light is reflected more stably in the louver structure region as the first structure region, and the incident angle dependency derived from the first structure region And the spreading angle of the diffused light can be further improved.

Moreover, in constructing the light-diffusion film of this invention, in the 2nd structural area, while making the maximum diameter in the cross section of a columnar thing into the value within the range of 0.1-15 micrometers, the distance between columnar objects is 0.1? It is preferable to set it as the value in the range of 15 micrometers, and to make a plurality of columnar objects stand at a predetermined inclination angle with respect to the film thickness direction.

By configuring in this way, incident light can be reflected more stably in the column structure area | region as a 2nd structure area | region, and the incident angle dependency derived from a 2nd structure area | region, and the spreading angle of diffused light can further be improved.

Moreover, in forming the light-diffusion film of this invention, in a 2nd structural area | region, the main component of a columnar product is a polymer of (meth) acrylic acid ester containing a some aromatic ring, and the main component of a medium is urethane (meth) It is preferable that it is a polymer of) acrylate.

By configuring in this way, not only the column structure as a 2nd structural area can be formed efficiently, but also the incident angle dependency and spreading angle of diffused light which originate in a 2nd structural area can be improved further.

Moreover, in forming the light-diffusion film of this invention, it is preferable to make thickness of a 2nd structural area into the value within the range of 5-495 micrometers.

In this configuration, the length of the columnar article along the film thickness direction is stably secured, the incident light is more stably reflected in the column structure region as the second structure region, and the incident angle dependence derived from the second structure region and The spreading angle of the diffused light can be further improved.

Moreover, another aspect of this invention is a manufacturing method of the light-diffusion film which has a 1st structural region for anisotropically diffusing incident light, and a 2nd structural region for isotropically diffusing incident light, Comprising: The following process (a)? ( It is a manufacturing method of the light-diffusion film characterized by including d).

(a) process of preparing the composition for light-diffusion films

(b) Process of apply | coating composition for light-diffusion film with respect to a process sheet, and forming an application layer

(c) Louver structure region formed by irradiating 1st active energy ray with respect to a coating layer, and arrange | positioning several plate-shaped area | regions which differ in refractive index as a 1st structural region in the lower part of an application layer along the film surface direction. And forming a louver structure unformed region in the upper portion of the coating layer

(d) The application layer is further irradiated with a second active energy ray, and a columnar image is formed in the louver structure unformed region with a plurality of columnar bodies having different refractive indices from the media in the media as the second structural region. Process of forming structural regions

That is, with the manufacturing method of the light-diffusion film of this invention, after forming the louver structure area | region as a 1st structural area | region by 1st active energy ray irradiation, and irradiating 2nd active energy ray, 1st structure In the unformed region existing above the region, a column structure region as the second structural region can be formed.

Therefore, the light-diffusion film which comprises the louver structure area | region as a 1st structural area | region and the column structure area | region as a 2nd structural area | region in the single film in the up-and-down order along the film thickness direction efficiently and also It can be manufactured stably.

Moreover, in implementing the manufacturing method of the light-diffusion film of this invention, it is preferable to irradiate the parallel light whose parallelism is a value of 10 degrees or less as 2nd active energy ray irradiation.

By implementing in this way, the column structure area | region as a 2nd structure area | region formed with the some inclined angle with respect to the film thickness direction can be manufactured efficiently and stably.

FIG. 1: (a)-(b) is a figure provided in order to demonstrate the outline of the louver structure in a 1st structural area.
FIG. 2: (a)-(b) is a figure provided in order to demonstrate incident light angle dependency and anisotropy in a louver structure.
FIG. 3: (a)-(b) is another figure provided in order to demonstrate incidence angle dependency in a louver structure.
4A and 4C are diagrams provided for explaining the angle of incidence and the spreading angle of diffused light.
FIG. 5: (a)-(b) is a figure provided in order to demonstrate the outline of the column structure in a 2nd structure area | region.
FIG. 6: (a)-(b) is a figure provided in order to demonstrate incidence angle dependence and isotropy in a columnar structure.
FIG. 7: (a)-(b) is a figure provided in order to demonstrate the outline of the light-diffusion film of this invention.
FIG. 8: (a)-(c) is a figure provided in order to demonstrate the aspect of the louver structure in a 1st structural area. FIG.
FIG. 9: (a)-(d) is a figure provided in order to demonstrate the aspect of the columnar structure in a 2nd structural area. FIG.
FIG. 10: is a figure provided in order to demonstrate the application example of the light-diffusion film of this invention in a reflection type liquid crystal display device.
FIG. 11: (a)-(b) is a figure provided in order to demonstrate a 1st active energy ray irradiation process. FIG.
12 (a) to 12 (b) are other diagrams provided for explaining the first active energy ray irradiation step.
FIG. 13: (a)-(c) is a figure provided in order to demonstrate a 2nd active energy ray irradiation process.
FIG. 14 (a)-(k) are figures provided in order to demonstrate the spread of the diffused light in the light-diffusion film of Example 1, and the distribution of the brightness.
FIG. 15 (a)-(b) are photographs provided in order to demonstrate the state of the cross section in the light-diffusion film of Example 1. FIG.
FIG. 16 is a view provided for explaining the light-diffusion film of Example 2. FIG.
17A and 17H are diagrams provided for explaining the spread of diffused light and the distribution of brightness in the light diffusing film of Example 3. FIG.
FIG. 18: (a)-(g) is a figure provided in order to demonstrate the spread of the diffused light in the light-diffusion film of Example 4, and the distribution of the brightness.
FIG. 19 (a)-(j) is a figure provided in order to demonstrate the spread of the diffused light in the light-diffusion film of the comparative example 1, and the distribution of the brightness.
20A to 20K are diagrams provided for explaining the spread of diffused light and the distribution of brightness in the light diffusing film of Comparative Example 2. FIG.
Fig. 21 (a)-(h) is a figure provided in order to demonstrate the spread of the diffused light in the light-diffusion film of the comparative example 3, and the distribution of the brightness.
22 (a) to 22 (i) are diagrams provided for explaining the spread of diffused light in the light diffusing film of Comparative Example 4 and the distribution of the brightness.
23 (a) to 23 (b) are diagrams provided for explaining a reflection type liquid crystal device using a conventional light diffusing film.

[First embodiment]

According to a first embodiment of the present invention, in a light diffusion film having a first structural region for anisotropically diffusing incident light and a second structural region for isotropically diffusing incident light, the first structural region has a refractive index. The plurality of other plate-shaped regions are arranged in parallel with each other along the film plane direction, and the second structural region is a column structure region formed by forming a plurality of columnar bodies having different refractive indices from the media in the media. It is a light-diffusion film characterized by the above-mentioned.

Hereinafter, the light-diffusion film which is 1st Embodiment of this invention is demonstrated concretely with reference to drawings.

1. Basic Principle

Hereinafter, the basic principle regarding the light diffusion by the louver structure and the light diffusion by the column structure in a light-diffusion film is demonstrated, respectively.

(1) Light Diffusion by Louver Structure

In FIG. 1 (a), only a louver structure region is shown, and a top view (top view) of the first structural region 10 for anisotropically diffusing incident light is shown. In FIG. 1 (b), FIG. The cross section of the 1st structural region 10 at the time of cut | disconnecting the 1st structural region 10 shown in the vertical direction along the dotted line AA, and looking at the cut surface from the arrow direction is shown.

In addition, in this invention, as shown in FIG.2 (a)-(b), when anisotropy diffuses with a film, in the surface parallel to the film in the diffused output light, It means that the light diffusion state (shape of spreading of the diffused light) has different properties depending on the direction in the same plane.

More specifically, in the case of the first structural region 10, mainly the diffused outgoing light is in a plane parallel to the film, and the light is directed in a direction perpendicular to the direction of the louver structure extending along the film plane direction. Since it is diffused, the shape of spreading of the diffused light becomes substantially elliptical.

As shown in the plan view of FIG. 1A, the first structural region 10 includes a plate region 12 having a relatively high refractive index and a plate region 14 having a relatively low refractive index along the film plane direction. It has the louver structure 13 which extends and arranges in parallel.

As shown in the cross-sectional view of FIG. 1B, the plate-shaped region 12 having a relatively high refractive index and the plate-shaped region 14 having a relatively low refractive index are each maintained with a predetermined thickness, and the first structural region ( Also in the vertical direction of 10), the state arrange | positioned in parallel with each other is maintained.

Accordingly, as shown in Figs. 2 (a) to 2 (b), when the incident angle is within the light diffusion incident angle region, it is estimated that the incident light is diffused along the first structural region 10.

That is, as shown in Fig. 1 (b), the incident angle of the incident light to the first structural region 10 is a value within a predetermined angle range from parallel to the boundary surface 13 'of the louver structure 13, That is, in the case of the value within the light diffusion incident angle region, the incident light 52, 54 passes through the inside of the high refractive index plate region 12 in the louver structure along the film thickness direction while changing the direction of the light on the light exit surface side. It is assumed that the traveling directions are the same.

As a result, when the incident angle is within the light diffusion incident angle region, it is estimated that the incident light is diffused along the first structural region 10 (52 ', 54').

In addition, as shown in FIGS. 2A to 6B, 6A to 6B, and 7A to 7B, the light diffusion incident angle region is a louver in the light diffusion film. It is an angular region determined for every light-diffusion film by the refractive index difference, inclination angle, etc. of a structure and a columnar structure.

In addition, the direction change of the incident light in the high refractive index plate-shaped area 12 in a louver structure becomes a step index type which changes in a zigzag direction linearly by total reflection as shown to FIG. 1 (b), It is also conceivable to have a gradient index type that changes direction in a curve.

On the other hand, when the incident angle of the incident light with respect to the first structural region 10 deviates from the light diffusion incident angle region, the incident light 56 does not diffuse along the first structural region 10 and is as it is. It is estimated to penetrate the structural region 10 of 56 '.

According to the above mechanism, the 1st structural region 10 provided with the louver structure 13 is incident angle dependence in the transmission and diffusion of light, for example, as shown to FIG.2 (a) (b). It becomes possible to exert.

As shown in Figs. 2 (a) to 2 (b), the first structural region has a light exit surface side even when the incident angle of the incident light is included in the light diffusion incident angle region, even when the incident angle is different. As a result, light diffusion can be almost performed.

Therefore, it can be said that the first structural region also has a light condensing effect of concentrating light at a predetermined location. This light condensing action is an action similarly to the second structural region described later and the light diffusing film of the present invention.

Here, the relationship between the incident angle of the incident light to the first structural region and the spreading angle of the diffused light diffused by the first structural region will be described with reference to Fig. 3A.

That is, in Fig. 3A, the characteristic curve is obtained by taking the incident angle (°) of the incident light with respect to the first structural region on the horizontal axis and the spreading angle (°) of the diffused light diffused by the first structural region on the vertical axis. Is shown.

In addition, as shown to Fig.4 (a)-(c), the incidence angle (theta) 1 means the angle (degree) in the case where the angle which injects perpendicular | vertical to the 1st structural area | region 10 is made 0 degree.

More specifically, as mentioned above, since the component of incident light which contributes to anisotropic light diffusion is a component perpendicular | vertical to the direction of the louver structure extended mainly to a film surface direction, it is called "incidence angle (theta) 1" of incident light in this invention. In this case, the incident angle of the component perpendicular to the direction of the louver structure extending in the film plane direction shall be taken. In addition, in this case, the incident angle θ1 shall mean an angle (°) when the angle with respect to the normal to the surface of the incident side of the light diffusion film is 0 °.

In addition, the spreading angle θ2 of the diffused light literally means the spreading angle (°) of the diffused light.

As the spreading angle of the diffused light increases, it means that light incident at the incident angle at that time is effectively diffused by the first structural region.

On the contrary, as the spreading angle of the diffused light becomes smaller, it means that the light incident at the incident angle at that time passes through the first structural region as it is and does not diffuse.

Moreover, the specific measuring method of the spreading angle of such diffused light is described in an Example.

That is, as understood from the characteristic curve shown in Fig. 3 (a), in the first structural region, the degree of transmission and diffusion of light is greatly changed by the difference in the incident angle, so that the light diffusion incident angle region and the other The incident angle region can be clearly separated.

On the other hand, in the case of the film having no incidence angle dependency, as shown in Fig. 3B, the change in the incidence angle does not have a definite influence on the degree of transmission and diffusion of light, and thus the light diffusion incident angle region cannot be recognized.

(2) Light Diffusion by Column Structure

In addition, in FIG. 5A, only the column structure region is shown, and a top view (top view) of the second structural region 20 for isotropically diffusing incident light is shown. In FIG. 5B, FIG. The cross section of the 2nd structural area | region 20 at the time of cut | disconnecting the 2nd structural area | region 20 shown to () in the vertical direction along the dotted line AA, and looking at the cut surface from the arrow direction is shown.

In addition, in the present invention, as shown in Figs. 6 (a) to 6 (b), when light is diffused by a film, in the plane parallel to the film in the emitted light, It means that the light diffusion state (shape of spreading of the diffused light) has a property that does not change with the direction in the same plane.

More specifically, in the case of the 2nd structural region 20, the diffused state of the diffused emitted light becomes circular in the surface parallel to a film.

Here, as shown in the plan view of FIG. 5A, the second structural region 20 includes a columnar body 22 having a relatively high refractive index and a medium 24 having a relatively low refractive index. 24)

As shown in the cross-sectional view of FIG. 5B, in the vertical direction of the second structural region 20, the columnar object 22 having a relatively high refractive index and the medium object 24 having a relatively low refractive index are respectively. It has a predetermined width and is arranged to each other.

Thus, as shown in Figs. 6A to 6B, when the incident angle is within the light diffusion incident angle region, it is estimated that the incident light is diffused by the second structural region 20.

That is, as shown in FIG. 5 (b), the incident angle of the incident light to the second structural region 20 is a value within a predetermined angle range from parallel to the boundary surface 23 ′ of the column structure 23, That is, in the case of the value within the light diffusion incident angle region, the incident light 62, 64 passes through the columnar 22 having a high refractive index in the columnar structure along the film thickness direction while changing the direction of the light on the light exit surface side. It is assumed that the traveling directions are the same.

As a result, when the incident angle is within the light diffusion incident angle region, it is estimated that the incident light is diffused along the second structural region 20 (62 ', 64').

In addition, the direction change of the incident light in the columnar 22 of high refractive index in a columnar structure becomes a step index type which changes in a zigzag direction linearly by total reflection as shown to FIG. 5 (b), It is also conceivable to have a gradient index type that changes in direction on a curve.

On the other hand, when the incident angle of the incident light with respect to the second structural region 20 deviates from the light diffusion incident angle region, the incident light 66 does not diffuse along the second structural region 20, and is as it is. It is estimated to penetrate the structural region 20 of (66 ').

According to the above mechanism, the 2nd structural region 20 provided with the columnar structure 23 is incident angle dependence in light transmission and diffusion, as shown to FIG. 6 (a) (b), for example. It becomes possible to exert.

In addition, since the relationship between the incident angle of the incident light to the second structural region and the spreading angle of the diffused light diffused by the second structural region is the same as in the first structural region described above, Omit the description.

2. Basic Configuration

Next, the basic structure of the light-diffusion film of this invention is demonstrated using drawing.

As shown to Fig.7 (a)-(b), the light-diffusion film 30 of this invention is a louver structure area | region (1st structure area | region) 10 for anisotropically diffusing incident light, and isotropic diffusion of incident light. It has a column structure area | region (2nd structure area | region) 20 for making it, Preferably, it is the structure which includes these structure area | regions sequentially in an up-down direction along a film thickness direction.

Therefore, in the light-diffusion film of this invention, as shown in FIG.7 (a), the unevenness of a diffusion characteristic is suppressed by overlapping the incident angle dependency which the 1st and 2nd structural area has, Not only can a favorable incident angle dependency be obtained, but also the spreading angle of diffused light can be effectively extended.

In addition, in the light-diffusion film of this invention, as shown in FIG.7 (b), the light-diffusion incidence angle area | region is made effective by shifting the incident angle dependency which the 1st and 2nd structural area has, It can be easily widened.

3. First structural area

The light diffusing film of the present invention is a first structural region for anisotropically diffusing incident light, and includes a plurality of plate regions having different refractive indices, that is, a plate region (high refractive index portion) having a relatively high refractive index and a plate having a relatively low refractive index. The region (low refractive index portion) has a louver structure region formed by being arranged in parallel with each other along the film plane direction.

Hereinafter, the first structural region will be described in detail.

(1) refractive index

In the first structural region, it is preferable that the difference in refractive index between the plate-shaped regions having different refractive indices, that is, the difference between the refractive index of the high refractive index portion and the refractive index of the low refractive index portion is set to a value of 0.01 or more.

The reason for this is that by setting the difference in refractive index to a value of 0.01 or more, the incident light is stably reflected in the louver structure region as the first structural region, and the incident angle dependency and spreading angle of the diffused light originating in the first structural region are adjusted. Because it can improve more.

More specifically, when the difference in refractive index is less than 0.01, the angle range at which the incident light totally reflects in the louver structure becomes narrow, so that the incidence angle dependency is excessively lowered, or the spreading angle of the diffused light is excessively narrowed. This is because there is a case.

Therefore, it is more preferable that the difference in refractive index between the plate-shaped regions having different refractive indices in the first structural region is set to a value of 0.05 or more, more preferably 0.1 or more.

Moreover, although the difference between the refractive index of a high refractive index part and the refractive index of a low refractive index part is so preferable that it is large, about 0.3 is considered an upper limit from a viewpoint of selecting the material which can form a louver structure.

In the first structural region, the refractive index of the plate region (high refractive index portion) having a relatively high refractive index is preferably set to a value within the range of 1.5 to 1.7.

This is because when the refractive index of the high refractive index portion is less than 1.5, the difference with the low refractive index portion becomes too small, which makes it difficult to obtain a desired louver structure.

On the other hand, when the refractive index of a high refractive index part becomes a value exceeding 1.7, it is because the compatibility between material materials in the composition for light-diffusion films may become excessively low.

Therefore, it is more preferable to make the refractive index of the high refractive index part in a 1st structural area into the value within the range of 1.52-1.65, and it is still more preferable to set it as the value within the range of 1.55-1.6.

In addition, the refractive index of a high refractive index part can be measured according to JISK0062.

In the first structural region, the refractive index of the plate region (low refractive index portion) having a relatively low refractive index is preferably set to a value within the range of 1.4 to 1.5.

This reason is because when the refractive index of such a low refractive index part is set to a value less than 1.4, the rigidity of the light-diffusion film obtained may fall.

On the other hand, when the refractive index of such a low refractive index part becomes a value exceeding 1.5, the difference with the refractive index of a high refractive index part becomes small too much, and it may become difficult to obtain a desired louver structure.

Therefore, it is more preferable to make the refractive index of the low refractive index part in a 1st structural area into the value within the range of 1.42-1.48, and it is still more preferable to set it as the value within the range of 1.44-1.46.

In addition, the refractive index in a low refractive index part can be measured according to JISK0062, for example.

(2) width

As shown in Figs. 8A to 8B, the widths S1 and S2 of the high refractive index portion 12 and the low refractive index portion 14 having different refractive indices in the first structural region, respectively, are shown. It is preferable to set it as the value within the range of 0.1-15 micrometers.

The reason for this is that by setting the width of these plate-shaped regions to a value within the range of 0.1 to 15 mu m, the incident light is more stably reflected in the louver structural region as the first structural region, and the incident originated in the first structural region. This is because the angle dependency and the spreading angle of the diffused light can be further improved.

That is, when the width | variety of such a plate-shaped area | region is set to a value less than 0.1 micrometer, it may become difficult to show light diffusivity regardless of the incident angle of incident light. On the other hand, when this width becomes a value exceeding 15 micrometers, the light which goes straight in a louver structure will increase and the uniformity of light diffusion may deteriorate.

Therefore, it is more preferable to make the width | variety of the plate-shaped area | region with which refractive index differs in a value in the range of 0.5-10 micrometers, respectively, and to set it as the value in the range which is 1-5 micrometers in a 1st structural area | region.

In addition, the width | variety, length, etc. of the plate-shaped area which comprise a louver can be calculated by observing with an optical digital microscope.

(3) length

As shown in Figs. 8A to 8B, the length L1 of the high refractive index portion 12 and the low refractive index portion 14 having different refractive indices in the first structural region is 5 to 495 µm, respectively. It is preferable to set it as the value within the range of.

This reason is that when such a length is less than 5 µm, the length of the louver structure is insufficient, and incident light that goes straight inside the louver structure increases, and it becomes difficult to obtain sufficient incident angle dependency and spreading angle of diffused light. Because there is.

On the other hand, when this length becomes a value exceeding 495 micrometers, when the active energy ray is irradiated to form the louver structure with respect to the composition for light-diffusion films, the advancing direction of photopolymerization will spread | diffused with the louver structure formed initially, It is because it may become difficult to form a desired louver structure.

Therefore, in the first structural region, it is more preferable to set the length of the plate-shaped region having different refractive indices to a value within the range of 40 to 310 μm, and more preferably to a value within the range of 95 to 255 μm. .

Moreover, as shown to FIG. 8 (b), the louver structure does not need to be formed in the upper-lower end part in a film thickness direction in a 1st structural area | region.

In this case, the width L2 of the upper and lower end portions where the louver structure is not formed may be the thickness of the first structural region, but in general, it is preferably a value within the range of 0 to 100 µm, and a value within the range of 0 to 50 µm. It is more preferable, and it is still more preferable that it is a value within the range of 0-5 micrometers.

(4) inclination angle

As shown in Figs. 8A to 8B, in the first structural region, the high refractive index portion 12 and the low refractive index portion 14 having different refractive indices have a constant inclination angle θa with respect to the film thickness direction. It is preferable to extend | stretch as.

This is because by making the inclination angle of the plate-shaped region constant, the incident light is more stably reflected in the louver structure region as the first structural region, and the incident angle dependency derived from the first structural region and the spreading angle of the diffused light are further increased. Because it can improve.

Moreover, as shown in FIG.8 (c), it is also preferable that the louver structure is bent.

This is because the louver structure is bent, thereby reducing the incident light that goes straight inside the louver structure and improving the uniformity of light diffusion.

Moreover, although this curved louver structure can be obtained by irradiating light, changing the irradiation angle of irradiation light, when performing the 1st active energy ray irradiation described in 2nd Embodiment, it forms a louver structure. The material depends greatly on the type of material.

Further, θa is the inclination angle of the plate-shaped region when the angle to the normal to the normal of the film surface measured in the cross section when the film is cut into a plane perpendicular to the louver structure extending along the film plane direction is 0 °. ).

More specifically, as shown in FIG. 8, the angle of a narrow side among the formation angles of the normal line of the film surface of an incident light irradiation side, and a plate-shaped area | region is meant. In addition, as shown in Fig. 8A, the inclination angle when the louver is inclined to the left is expressed on the basis of the inclination angle when the louver is inclined to the right.

(5) thickness

Moreover, it is preferable to make thickness of a 1st structural area into the value within the range of 5-495 micrometers.

This is because by setting the thickness of the first structural region to a value within this range, the length of the louver structure along the film thickness direction can be stably secured, and the incident light in the louver structural region as the first structural region more stably. This is because it is possible to further improve the incident angle dependency and spreading angle of the diffused light originating from the first structural region by reflecting.

That is, if the thickness of the first structural region is less than 5 µm, the length of the louver structure is insufficient, and incident light that goes straight inside the louver structure increases, thereby obtaining sufficient incidence angle dependency and spreading angle of diffused light. This is because it may become difficult.

On the other hand, when the thickness of the first structural region is greater than 495 µm, the photopolymerization progresses by the louver structure initially formed when irradiating active energy rays to the light diffusing film composition to form a louver structure. It is because a direction may diffuse and it may become difficult to form a desired louver structure.

Therefore, it is more preferable to make the thickness of a 1st structural area into the value within the range of 40-310 micrometers, and it is still more preferable to set it as the value within the range of 95-255 micrometers.

(6) material materials

(6) -1 high refractive index part

Further, in the first structural region, the kind of material material for forming the high refractive index portion, which is a plate region having a relatively high refractive index, among the plate regions having different refractive indices, is not particularly limited, but the main component may be a plurality of aromatic rings. It is preferable to set it as the polymer of (meth) acrylic acid ester to contain.

This is because, with such a material material, not only the louver structure as the first structural region can be formed efficiently, but also the incident angle dependency and spreading angle of the diffused light derived from the first structural region can be further improved. to be.

That is, the main component (hereinafter sometimes referred to as (A1) component) of the high refractive index portion is a polymer of a specific (meth) acrylic acid ester to form the first structural region by polymerization (A1) component. The main component of the low refractive index portion having a low refractive index, which will be described later, depending on the polymerization rate of the monomer component (hereinafter, sometimes referred to as monomer (A1) component) may be referred to as component (hereinafter, referred to as (B1) component). It is estimated that it can make it faster than the superposition | polymerization rate of the monomer component (Hereinafter, it may be called a monomer (B1) component.).

And a predetermined difference arises in the superposition | polymerization rate between these monomer components, and it suppresses the copolymerization of both monomer components uniformly, More specifically, it reduces the compatibility of both monomer components to a predetermined range. It is estimated that copolymerization property of both monomer components can be reduced effectively.

As a result, the louver structure in which (A1) component and (B1) component extended mutually along the film surface inside direction can be formed efficiently by irradiation of an active energy ray.

Moreover, by using specific (meth) acrylic acid ester as a monomer (A1) component, compatibility with a monomer (B1) component can be reduced to a predetermined range, and a louver structure can be formed more efficiently.

Furthermore, by containing the polymer of specific (meth) acrylic acid ester as (A1) component, the refractive index of the plate-shaped area | region derived from the (A1) component in louver structure is made high, and the plate-shaped area | region derived from (B1) component The difference with the refractive index of can be adjusted to a predetermined value or more.

Therefore, by containing the polymer of specific (meth) acrylic acid ester as (A1) component, the hardened | cured material from which refractive index differs with the characteristic of (B1) component mentioned later is mutually extended along the direction of a film plane inside the louver structure. It can be obtained efficiently.

Therefore, while having a good incidence angle dependency in the transmission and diffusion of light, a first structural region having a wide light diffusion incidence angle region can be obtained.

Moreover, "(meth) acrylic acid ester containing a plurality of aromatic rings" means the compound which has a some aromatic ring in the ester part of (meth) acrylic acid ester.

In addition, "(meth) acrylic acid" means both acrylic acid and methacrylic acid.

Moreover, as (meth) acrylic acid ester containing the some aromatic ring as a monomer (A1) component which comprises such a (A1) component, it is (meth) acrylic-acid biphenyl, (meth) acrylic-acid naphthyl, ( (Meth) acrylic acid benzylphenyl, (meth) acrylic acid benzylphenyl, (meth) acrylic acid biphenyloxyalkyl, (meth) acrylic acid naphthyloxyalkyl, (meth) acrylic acid anthracyloxyalkyl, (meth) acrylic acid benzylphenyloxyalkyl, Alternatively, some of these may be substituted with halogen, alkyl, alkoxy, alkyl halide or the like.

Moreover, as (meth) acrylic acid ester containing the some aromatic ring as the monomer (A1) component which comprises (A1) component, it is preferable to contain the compound containing a biphenyl ring, Especially, following General formula (1) It is preferable to contain the biphenyl compound represented by).

(In General formula (1), R <^1> -R <^10> is respectively independent and R <^1> -R <^10>. At least 1 is a substituent represented by following General formula (2), and the remainder is a substituent which is any one of 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. to be.)

(In General Formula (2), R ¹¹ is a hydrogen atom or a methyl group, carbon number n is an integer of 1 to 4, and the repeating number m is an integer of 1 to 10.)

This is because by using a biphenyl compound having a specific structure as the monomer (A1) component constituting the component (A1), the polymerization rate of the monomer (A1) component is higher than the polymerization rate of the monomer (B1) component, It is estimated that it can be done faster.

In addition, it is estimated that the compatibility with the monomer (B1) component can be more easily reduced to a predetermined range, and the refractive index of the plate region derived from the component (A1) in the louver structure is made higher. , The difference with the refractive index of the plate-shaped region derived from the component (B1) can be more easily adjusted to a predetermined value or more.

Furthermore, it is liquid at the monomer stage before photocuring, and even if it does not use a dilution solvent etc., it can mix uniformly with the urethane (meth) acrylate which is a typical example of a monomer (B1) component.

In addition, when R <^1> -R <^10> in General formula (1) contains any of an alkyl group, an alkoxy group, a halogenated alkyl group, a hydroxyalkyl group, and a carboxyalkyl group, carbon number of the alkyl part is 1-4. It is preferable to set it as the value within a range.

The reason for this is that if the number of carbon atoms is more than 4, the polymerization rate of the monomer (A1) component is lowered, or the refractive index of the plate-shaped region derived from the component (A1) in the louver structure is too low. It is because it may become difficult to form a predetermined louver structure in the structural region of 1 efficiently.

Therefore, when R <^1> -R <^10> in General formula (1) contains any of an alkyl group, an alkoxy group, a halogenated alkyl group, a hydroxyalkyl group, and a carboxyalkyl group, carbon number of the alkyl part is 1-3, It is more preferable to set it as the value within a range, and it is still more preferable to set it as the value within the range of 1-2.

In addition, it is preferable that R <^1> -R <^10> in General formula (1) is a substituent other than a halogenated alkyl group or a halogen atom, ie, a substituent which does not contain a halogen.

This is because dioxins are prevented from being generated when the light diffusion film is incinerated and the like is preferable from the viewpoint of environmental protection.

Moreover, in the anisotropic light-diffusion film provided with the conventional louver structure, in order to obtain a predetermined louver structure and to high refractive index of a monomer component, it was common to perform halogen substitution in a monomer component.

For this reason, as long as it is a biphenyl compound represented by General formula (1), even if halogen substitution is not performed, it can be set as high refractive index.

Therefore, by using the biphenyl compound represented by General formula (1) as a monomer (A1) component, even when it does not contain a halogen, favorable incident angle dependence can be exhibited.

Moreover, it is preferable that any one of R <^2> -R <^9> in General formula (1) is a substituent represented by General formula (2).

This is because the monomer (A1) components are oriented in the step before photocuring by setting the position of the substituent represented by the general formula (2) to a position other than R ¹ and R ¹⁰ in the biphenyl ring. This can effectively prevent crystallization.

Accordingly, in the step of photocuring, aggregation phase separation at a fine level of the monomer (A1) component and the monomer (B1) component is enabled, and the first structural region having a predetermined louver structure can be more efficiently. Because you can get

Furthermore, it is especially preferable that any one of R <^3> , R <^5> , R <^6> and R <^8> in General formula (1) is a substituent represented by General formula (2).

In addition, it is preferable to make the repeating number m in the substituent represented by General formula (2) as an integer of 1-10 normally.

The reason for this is that when the repeating number m becomes a value exceeding 10, the oxyalkylene chain connecting the polymerization site and the biphenyl ring becomes too long, and the polymerization of the monomers (A1) components in the polymerization site may be inhibited. Because there is.

Therefore, it is more preferable to make the repeating number m in the substituent represented by General formula (2) into an integer of 1-4, and it is especially preferable to set it as an integer of 1-2.

Moreover, it is preferable to make carbon number n in the substituent represented by General formula (2) into an integer of 1-4 normally from a same viewpoint.

In particular, the position of the polymerizable carbon-carbon double bond as a polymerization site is too close to the biphenyl ring, and the biphenyl ring becomes a steric hindrance, and from the viewpoint of preventing the polymerization rate of the monomer (A1) component from decreasing, It is more preferable to make carbon number n in the substituent represented by (2) into an integer of 2-4, and it is more preferable to set it as an integer of 2-3.

Moreover, as a specific example of the biphenyl compound represented by General formula (1), the compound represented by following formula (3)-(4) is mentioned.

Moreover, it is preferable to make the weight average molecular weight of the monomer (A1) component which comprises (A1) component into the value within the range of 200-2500.

The reason for this is that by setting the weight average molecular weight of the monomer (A1) component within a predetermined range, the polymerization rate of the monomer (A1) component is made faster and the copolymerizability of the monomer (A1) component and the monomer (B1) component is more effectively. It is because it is estimated that it can reduce.

As a result, at the time of photocuring, the louver structure which the (A1) component and (B1) component extended mutually along the film surface direction can be formed more efficiently.

In other words, when the weight average molecular weight of the monomer (A1) component is less than 200, for example, the positions of the plurality of aromatic rings and the positions of the polymerizable carbon-carbon double bonds become too close, and the polymerization rate is increased due to steric hindrance. It is because it may fall, near the polymerization rate of a monomer (B1) component, and copolymerization with a monomer (B1) component may occur easily. On the other hand, when the weight average molecular weight of the monomer (A1) component exceeds a value of 2,500, the polymerization rate of the monomer (A1) component decreases and approaches the polymerization rate of the monomer (B1) component and copolymerizes with the monomer (B1) component. This is because, as a result, the louver structure may be difficult to be formed efficiently.

Therefore, it is more preferable to make the weight average molecular weight of a monomer (A1) component into the value within the range of 240-1,500, and it is still more preferable to set it as the value within the range of 260-1,000.

In addition, the weight average molecular weight of a monomer (A1) component can be measured using gel permeation chromatography (GPC), or can be calculated from a structural formula based on the atomic weight of a constituent atom.

Moreover, it is preferable to make the monomer (A1) component which forms the plate-shaped area | region with high refractive index in louver structure into single.

The reason for this is to provide a structure having a predetermined louver structure by effectively suppressing the unevenness of the refractive index in the plate-shaped region derived from the component (A1) in the louver structure, that is, the plate-shaped region having a high refractive index. This is because the structural region of 1 can be obtained more efficiently.

That is, when the monomer (A1) component has low compatibility with the monomer (B1) component, for example, when the monomer (A1) component is a halogen-based compound or the like, the monomer (A1) component is replaced by the monomer (B1) component. As a 3rd component for making it compatible, the other monomer (A1) component (for example, non-halogen type compound etc.) may be used together.

However, in this case, depending on the influence of such a 3rd component, the refractive index in the plate-shaped area | region with a high refractive index derived from (A1) component may be uneven or it may fall.

As a result, there may be a case where the refractive index difference with the plate-shaped region having a low refractive index derived from the component (B1) becomes nonuniform or easily decreases excessively.

Therefore, it is preferable to select a high refractive index monomer component having compatibility with the monomer (B1) component and use it as a single monomer (A1) component.

For example, the biphenyl compound represented by Formula (3)-(4) as a monomer (A1) component has compatibility with the monomer (B1) component, and therefore can be used as a single monomer (A1) component. Can be.

(6) -2 low refractive index part

Further, in the first structural region, the type of material material for forming the low refractive index portion, which is a plate region having a low refractive index, among the plate regions having different refractive indices, is not particularly limited, but the main component is a urethane (meth) acrylate. It is preferable to set it as a polymer.

This is because, with such a material material, not only the louver structure as the first structural region can be formed efficiently, but also the incident angle dependency and spreading angle of the diffused light derived from the first structural region can be further improved. to be.

That is, by making the main component ((B1) component) of a low refractive index part into the polymer of urethane (meth) acrylate, the refractive index of the plate-shaped area | region derived from (A1) component, and the refractive index of the plate-shaped area | region derived from (B1) component Not only can the difference be more easily adjusted, but also the unevenness of the refractive index of the plate-shaped region derived from the component (B1) can be effectively suppressed, so that the first structural region having a predetermined louver structure can be obtained more efficiently. Because there is.

In addition, (meth) acrylate means both an acrylate and a methacrylate.

First, the urethane (meth) acrylate as the monomer (B1) component constituting the component (B1) comprises (a) a compound containing at least two isocyanate groups, (b) polyalkylene glycols, and (c) hydroxyalkyl. It is formed from (meth) acrylate.

Among these, as a compound containing at least two isocyanate groups which are (a) component, For example, 2, 4- tolylene diisocyanate, 2, 6- tolylene diisocyanate, 1, 3- xylylene diisocyanate, 1, 4 Alicyclic polyisocyanates such as aromatic polyisocyanates such as xylylene diisocyanate, aliphatic polyisocyanates such as hexamethylene diisocyanate, isophorone diisocyanate (IPDI), hydrogenated diphenylmethane diisocyanate, and biuret bodies and iso Adducts (e.g., xylylenediisocyanate-based trifunctional adducts) that are reactants with low molecular weight active hydrogen-containing compounds such as cyanurate, ethylene glycol, propylene glycol, neopentyl glycol, trimethylolpropane, castor oil, etc. ), And the like.

Moreover, it is preferable also that it is alicyclic polyisocyanate among the above-mentioned.

The reason for this is that, in the case of alicyclic polyisocyanate, it is easy to provide a difference in the reaction rate of each isocyanate group in comparison with aliphatic polyisocyanate according to the relation of the stereostructure and the like, and the molecular design of the urethane (meth) acrylate obtained is Because it is easy.

Moreover, it is especially preferable that (a) component is alicyclic diisocyanate.

This reason is, if it is alicyclic diisocyanate, it suppresses that (a) component reacts only with (b) component or (a) component reacts only with (c) component, for example, (a) component This is because it is possible to reliably react with the component (b) and the component (c), and it is possible to prevent the occurrence of extra side products.

As a result, the unevenness of the refractive index in the plate-shaped region derived from the component (B1) in the first structural region, that is, the plate-shaped region of low refractive index can be effectively suppressed.

Moreover, if it is alicyclic diisocyanate, compared with aromatic diisocyanate, the compatibility of the monomer (B1) component obtained and the biphenyl compound which has a specific structure which is a typical example as a monomer (A1) component will be reduced to a predetermined range, The louver structure can be formed more efficiently.

Furthermore, in the case of an alicyclic diisocyanate, since the refractive index of the monomer (B1) component obtained can be made small compared with an aromatic diisocyanate, with the refractive index of the biphenyl compound which has a specific structure which is a typical example of a monomer (A1) component. By making the difference larger, the louver structure excellent in the incident angle dependency can be formed more efficiently.

Moreover, in such alicyclic diisocyanate, it is especially preferable that it is isophorone diisocyanate (IPDI) from a big difference in the reactivity of two isocyanate groups.

In addition, as a polyalkylene glycol which is (b) component among the components which form the urethane (meth) acrylate as a monomer (B1) component, for example, polyethyleneglycol, polypropylene glycol, polybutylene glycol, polyhexylene Glycol etc. are mentioned, Especially, it is especially preferable that it is polypropylene glycol.

This reason is because polypropylene glycol can be handled as a solvent without the viscosity being low.

Moreover, when it is polypropylene glycol, when hardening a monomer (B1) component, it becomes a favorable soft segment in the said hardened | cured material, and since handling property and mountability of a light-diffusion film can be improved effectively, to be.

In addition, the weight average molecular weight of a monomer (B1) component can be adjusted according to the weight average molecular weight of (b) component. Here, the weight average molecular weight of (b) component is 2,300-19,500 normally, Preferably it is 4,300-14,300, Especially preferably, it is 6,300-12,300.

Moreover, as a hydroxyalkyl (meth) acrylate which is (c) component among the components which form the urethane (meth) acrylate as a monomer (B1) component, For example, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 3-hydroxybutyl (meth) acrylate, 4-hydroxybutyl ( Meth) acrylate, etc. are mentioned.

Moreover, it is more preferable that it is hydroxyalkyl methacrylate especially from a viewpoint of reducing the superposition | polymerization rate of the urethane (meth) acrylate obtained and forming a predetermined louver structure more efficiently, and 2-hydroxyethyl methacryl It is more preferable that it is a rate.

In addition, the synthesis | combination of urethane (meth) acrylate by (a)-(c) component can be performed in accordance with a conventional method.

At this time, it is preferable to make the compounding ratio of (a)-(c) component into the ratio of (a) component: (b) component: (c) component = 1-5: 1: 1-5 by molar ratio.

This reason is, by setting it as such a compounding ratio, the one isocyanate group which (a) component has respectively reacted and couple | bonds with respect to the two hydroxyl groups which (b) component has, Furthermore, the other one which the two (a) components have respectively It is because the urethane (meth) acrylate which the hydroxyl group which (c) component has reacted and couple | bonded with the isocyanate group of can react efficiently.

Therefore, it is more preferable to make the compounding ratio of (a)-(c) component into the ratio of (a) component: (b) component: (c) component = 1-1: 1: 1-3 by molar ratio, More preferably, the ratio is 2: 1: 2.

Moreover, it is preferable to make the weight average molecular weight of the monomer (B1) component which comprises (B1) component into the value within the range of 3,000-20,000.

This is because by setting the weight average molecular weight of the monomer (B1) component within a predetermined range, a predetermined difference is generated in the polymerization rate of the monomer (A1) component and the monomer (B1) component, thereby effectively decreasing the copolymerizability of both components. It is estimated that it can be done.

As a result, at the time of photocuring, the louver structure in which (A1) component and (B1) component mutually extended can be formed efficiently.

In other words, when the weight average molecular weight of the monomer (B1) component is less than 3,000, the polymerization rate of the monomer (B1) component is increased, and the polymerization rate of the monomer (A1) component is approached, and the copolymerization with the monomer (A1) component is reduced. It is because it may become difficult to form a louver structure efficiently as a result which becomes easy to occur. On the other hand, when the weight average molecular weight of the monomer (B1) component exceeds a value of 20,000, it becomes difficult to form a louver structure in which the component (A1) and the component (B1) extend in the film plane direction, or the monomer (A1 This is because the compatibility with the) component may be excessively lowered, and the monomer (A1) component may be precipitated at the application step of the composition for light-diffusion film.

Therefore, it is more preferable to make the weight average molecular weight of a monomer (B1) component into the value within the range of 5,000-15,000, and it is still more preferable to set it as the value within the range of 7,000-13,000.

In addition, the weight average molecular weight of a monomer (B1) component can be measured using gel permeation chromatography (GPC), or can be calculated from a structural formula based on the atomic weight of a constituent atom.

In addition, although the monomer (B1) component may use together 2 or more types whose molecular structure and weight average molecular weight differ, from a viewpoint of suppressing the unevenness of the refractive index of the plate-shaped area | region derived from the (B1) component in louver structure, It is preferable to use only one type.

That is, when a plurality of monomer (B1) components are used, the refractive index in the plate region having a low refractive index derived from the component (B1) is uneven or high, and the plate-shaped region having a high refractive index derived from the component (A1) and This is because the difference in refractive index may become nonuniform or excessively lower.

4. Second structural area

The light diffusing film of the present invention is a second structural region for isotropically diffusing incident light, and has a column structure region in which a plurality of columnar objects having different refractive indices from the medium are formed in the medium.

Hereinafter, a 2nd structural area is demonstrated concretely.

(1) refractive index

In the second structural region, the difference between the refractive index of the columnar product and the refractive index of the medium is preferably 0.01 or more.

The reason for this is that by setting the difference in refractive index to a value of 0.01 or more, the incident light is stably reflected in the column structure region as the second structural region, and the incident angle dependency and spreading angle of the diffused light originating in the second structural region are reduced. Because it can improve more.

In other words, when the difference in refractive index is less than 0.01, the angle range at which the incident light totally reflects in the column structure is narrowed, so that the incident angle dependency is excessively lowered or the spreading angle of the diffused light is too narrow. Because there is.

Therefore, the difference between the refractive index of the columnar product in the second structural region and the refractive index of the medium is more preferably 0.05 or more, and even more preferably 0.1 or more.

Moreover, although the difference of refractive index is so preferable that it is large, about 0.3 is considered an upper limit from a viewpoint of selecting the material which can form a columnar structure.

(2) the maximum diameter

In addition, as shown to Fig.9 (a), it is preferable to make the maximum diameter S3 in the cross section of a columnar object into the value within the range of 0.1-15 micrometers in a 2nd structural area.

The reason for this is that by setting this maximum diameter to a value within the range of 0.1 to 15 mu m, the incident light is more stably reflected in the column structure region as the second structure region, and the incident angle dependence derived from the second structure region and This is because the spreading angle of the diffused light can be further improved.

That is, when this maximum diameter is made into the value below 0.1 micrometer, it may become difficult to show light diffusivity irrespective of the incident angle of incident light. On the other hand, when this maximum diameter becomes a value exceeding 15 micrometers, the light which goes straight in a columnar structure may increase, and uniformity of light diffusion may deteriorate.

Therefore, in a 2nd structural area, it is more preferable to make the maximum diameter in the cross section of a columnar thing into the value within the range of 0.5-10 micrometers, and it is still more preferable to set it as the value within the range which is 1-5 micrometers.

Moreover, about the cross-sectional shape of a columnar object, although it does not specifically limit, For example, it is preferable to set it as a circle, an ellipse, a polygon, a mold release, etc.

In addition, the cross section of a columnar object means the cross section cut | disconnected by the surface parallel to a film surface.

In addition, the maximum diameter, length, etc. of a columnar object can be computed by observing with an optical digital microscope.

(3) length

Moreover, in 2nd structural area, it is preferable to make length L3 of a columnar object into the value within the range of 5-495 micrometers.

The reason for this is that when the length is less than 5 µm, the length of the columnar product is insufficient, and incident light that goes straight through the column structure increases, making it difficult to obtain sufficient incident angle dependence and spreading angle of diffused light. Because there is.

On the other hand, when this length becomes a value exceeding 495 micrometers, when the active energy ray is irradiated to the composition for light-diffusion films, and the column structure is formed, the advancing direction of photopolymerization will spread | diffused by the column structure initially formed, This is because it may be difficult to form a desired column structure.

Therefore, in a 2nd structural area, it is more preferable to make the length of a columnar object into the value within the range of 40-310 micrometers, and it is still more preferable to set it as the value within the range of 95-255 micrometers.

In addition, as shown in Fig. 9C, the column structure may not be formed even in the upper and lower end portions in the film thickness direction in the second structural region.

In this case, the width L4 of the upper and lower end portions in which the column structure is not formed may be the thickness of the second structural region, but in general, it is preferably a value within the range of 0 to 50 µm, and preferably within the range of 0 to 5 µm. It is more preferable that it is a value.

(4) the distance between pillars

In addition, as shown to Fig.9 (a), in 2nd structural area | region, the distance between columnar objects, ie, the space P in adjacent columnar objects, is set to the value within the range of 0.1-15 micrometers. It is desirable to.

The reason for this is that by setting the distance within a range of 0.1 to 15 mu m, the incident light is more stably reflected in the column structure area as the second structure area, and the incident angle dependency and diffusion originating from the second structure area. This is because the spreading angle of the light can be further improved.

That is, when this distance is made into the value below 0.1 micrometer, it may become difficult to show light diffusivity irrespective of the incident angle of incident light. On the other hand, when this distance becomes a value exceeding 15 micrometers, the light which goes straight in a column structure will increase, and the uniformity of light diffusion may deteriorate.

Therefore, in a 2nd structural area, it is more preferable to make the distance between columnar objects into the value within the range of 0.5-10 micrometers, and it is still more preferable to set it as the value within the range which is 1-5 micrometers.

(5) inclination angle

In addition, as shown to FIG.9 (b) (c), in the 2nd structural area, it is preferable that the columnar object 22 stands by the inclination-angle (theta) b with respect to a film thickness direction.

This is because by making the inclination angle of the columnar constant constant, incident light is more stably reflected in the column structure area as the second structure area, further improving the incident angle dependency derived from the second structure area and the spreading angle of the diffused light. Because you can.

Moreover, as shown in FIG.9 (d), it is also preferable that the columnar object is bent.

This is because the incident light leading straight through the column structure can be reduced by the bending of the columnar material, thereby improving the uniformity of the light diffusion.

In addition, this curved columnar object can be obtained by irradiating light while changing the irradiation angle of irradiation light when performing the 2nd active energy ray irradiation described in 2nd Embodiment, but forming a column structure. The material depends greatly on the type of material.

Moreover, (theta) b is a surface perpendicular | vertical to a film surface, and made the angle with respect to the normal of the film surface measured in the cross section at the time of cut | disconnecting a film by the surface which cuts one whole columnar object in two along an axis to 0 degree. It means the angle of inclination (°) of the columnar body in the case (the angle of the narrow side between the normal line and the angle of formation of the columnar body). In addition, as shown in Fig. 9B, the inclination angle when the column is inclined to the left is negatively expressed based on the inclination angle when the column is inclined to the right.

(6) thickness

Moreover, it is preferable to make thickness of a 2nd structural area into the value within the range of 5-495 micrometers.

The reason for this is that by setting the thickness of the second structural region to a value within this range, the length of the columnar article along the film thickness direction is stably secured, and the incident light is more stably reflected in the column structural region as the second structural region. This is because the incident angle dependency and the spreading angle of the diffused light derived from the second structural region can be further improved.

In other words, if the thickness is less than 5 µm, the length of the columnar article is insufficient, and incident light that goes straight inside the columnar structure increases, which may make it difficult to obtain sufficient incident angle dependence and spreading angle of diffused light. to be. On the other hand, when this thickness becomes a value exceeding 495 micrometers, when the active energy ray is irradiated to the composition for light-diffusion films to form a column structure, the advancing direction of photopolymerization will spread | diffused by the column structure initially formed, This is because it may be difficult to form a desired column structure.

Therefore, it is more preferable to make the thickness of a 2nd structural area into the value within the range of 40-310 micrometers, and it is still more preferable to set it as the value within the range of 95-255 micrometers.

(7) material materials

(7) -1 column

In addition, in the 2nd structural region, although the kind of material substance which comprises a columnar material is not specifically limited, It is preferable to make the main component into the polymer of (meth) acrylic acid ester containing a some aromatic ring.

This is because, with such a material material, not only can the column structure as the second structural region be efficiently formed, but also the incident angle dependence and the spreading angle of the diffused light derived from the second structural region can be further improved. to be.

That is, when the main component (hereinafter sometimes referred to as (A2) component) of the columnar product is a polymer of a specific (meth) acrylic acid ester, when the second structural region is formed, the component (A2) Monomer component which becomes the main component (hereinafter may be referred to as (B2) component) of the medium of the media mentioned later according to superposition | polymerization rate of the monomer component (Hereinafter, it may be called a monomer (A2) component.) In the following, the monomer (B2) component may be referred to below), and a predetermined difference may be generated in the polymerization rate between these monomer components, thereby effectively decreasing the copolymerizability of both monomer components. It is estimated.

As a result, the columnar structure in which columnar objects composed of the component (A2) stand in the medium formed of the component (B2) can be efficiently formed by irradiation with active energy rays.

In addition, by using a specific (meth) acrylic acid ester as the monomer (A2) component, the compatibility with the monomer (B2) component is reduced to a predetermined range, and it is estimated that the column structure can be formed more efficiently. do.

Furthermore, by using a specific (meth) acrylic acid ester as the monomer (A2) component, the refractive index of the columnar product derived from the component (A2) in the columnar structure is made high, and the refractive index of the medium product derived from the component (B2) The difference of can be adjusted to a predetermined value or more.

Therefore, by containing the polymer of a specific (meth) acrylic acid ester as (A2) component, the columnar object which consists of (A2) component is standing in the medium which consists of (B2) component with the characteristic of (B2) component mentioned later. One column structure can be efficiently obtained.

Therefore, while having good incidence angle dependency in transmission and diffusion of light, a second structural region having a wide light diffusion incidence angle region can be obtained.

Moreover, regarding the detail of the (meth) acrylic acid ester containing the some aromatic ring as the monomer (A2) component which comprises (A2) component, it overlaps with the content of the monomer (A1) component in a 1st structural area. Therefore, it is omitted.

(7) -2 media

In addition, the kind of material substance which comprises a medium in a 2nd structural area is not specifically limited, It is preferable to make the main component into the polymer of urethane (meth) acrylate.

This is because, with such a material material, not only can the column structure as the second structural region be efficiently formed, but also the incident angle dependence and the spreading angle of the diffused light derived from the second structural region can be further improved. to be.

That is, by making the main component ((B2) component) of a media material into the polymer of urethane (meth) acrylate, the difference between the refractive index of the columnar product derived from (A2) component, and the refractive index of the media material derived from (B2) component, This is because not only can be adjusted more easily, but also the unevenness of the refractive index of the medium derived from the component (B2) can be effectively suppressed, so that a second structural region having a predetermined column structure can be obtained more efficiently.

In addition, the detail of the urethane (meth) acrylate as a monomer (B2) component which comprises (B2) component overlaps with the content of the monomer (B1) component in a 1st structural area, and it abbreviate | omits.

5. Total film thickness

Moreover, it is preferable to make the total film thickness of the light-diffusion film of this invention into the value within the range of 50-500 micrometers.

This reason is because when the total film thickness of a light-diffusion film is set to a value less than 50 micrometers, the light which goes straight in a columnar structure and a louver structure may increase, and it may become difficult to show light diffusivity. On the other hand, when the total film thickness of the light-diffusion film is a value exceeding 500 μm, when the active energy ray is irradiated to the composition for the light-diffusion film to form a column structure and a louver structure, the column structure and the louver structure initially formed are This is because the advancing direction of the photopolymerization may diffuse, making it difficult to form a desired column structure and louver structure.

Therefore, it is more preferable to make the total film thickness of a light-diffusion film into the value within the range of 80-350 micrometers, and it is still more preferable to set it as the value within the range which is 100-260 micrometers.

Moreover, the light-diffusion film of this invention may be the structure which has the 1st and 2nd structural area | region in a single film, and the structure which laminated | stacked the film which has only a 1st structural area | region and the film which has only a 2nd structural area | region is laminated | stacked. It may be.

In particular, when laminating the first and second structural regions, bubbles can be essentially suppressed from occurring in the form of bubbles, and therefore, a structure in which both structures are formed in a single film is more preferable.

Moreover, what is necessary is just to provide a 1st structural area | region and a 2nd structural area | region in the up-down direction one by one along the film thickness direction of a light-diffusion film, The order and number in particular are not restrict | limited.

6. Combination of angles of inclination

Moreover, with the light-diffusion film of this invention, the inclination angle (theta) a of the plate-shaped area | region with respect to the film thickness direction in a 1st structural area | region, and the inclination angle (theta) b of the columnar product with respect to the film thickness direction in a 2nd structural area | region are By adjusting each, the light-diffusion characteristic can be changed.

For example, by overlapping the incidence angle dependence of each structural region, the unevenness of the diffusion characteristic can be suppressed and a good incidence angle dependency can be obtained, and the spreading angle of the diffused light can be effectively widened.

In this case, the inclination angle θa of the plate-like region with respect to the film thickness direction in the first structural region is set to a value within the range of -80 ° to 80 °, and in the second structural region with respect to the film thickness direction. It is preferable to set the inclination angle θb of the columnar product to a value within the range of -80 to 80 °, and to set the absolute value of θa to θb to a value within the range of 0 to 80 °, and set the absolute value of θa to θb to 5 ?. It is more preferable to set it as the value within the range of 20 degrees.

In addition, the content of (theta) a and (theta) b here is as having already demonstrated.

Further, by shifting the incident angle dependency of each structural region, the light diffusion incident angle region can be effectively and easily widened.

In this case, the inclination angle θa of the plate-like region with respect to the film thickness direction in the first structural region is set to a value within the range of -80 ° to 80 °, and in the second structural region with respect to the film thickness direction. It is preferable that the inclination angle θb of the columnar article be a value within the range of -80 ° to 80 °, and the absolute value of θa-θb be a value within the range of 5 to 60 °, and the absolute value of θa-θb be 20 to 45 degrees. It is more preferable to set it as the value within the range of °.

7. Uses

10, it is preferable to use the light-diffusion film of this invention for the reflective liquid crystal display device 100. As shown in FIG.

This is because, with the light diffusing film of the present invention, it is possible to efficiently diffuse external light so as to condense and efficiently transmit external light to be absorbed into the liquid crystal display device and to use the light as a light source.

Therefore, the light-diffusion film of this invention is arrange | positioned on the upper surface or lower surface of the liquid crystal cell 110 which consists of glass plates 104 and 108, the liquid crystal 106, and the mirror surface reflecting plate 107, etc., and reflects it. It is preferable to use it as the light-diffusion plate 103 in the type liquid crystal display device 100.

Moreover, by providing the light-diffusion film of this invention to the polarizing plate 101 and the retardation plate 102, an optical viewing angle polarizing plate and an optical viewing phase difference plate can be obtained.

[Second embodiment]

According to a second embodiment of the present invention, there is provided a method for producing a light-diffusion film having a first structural region for anisotropically diffusing incident light and a second structural region for isotropically diffusing incident light. It is a manufacturing method of the light-diffusion film characterized by including (d).

(a) process of preparing the composition for light-diffusion films

(b) Process of apply | coating composition for light-diffusion film with respect to a process sheet, and forming an application layer

(c) Louver structure region formed by irradiating 1st active energy ray with respect to a coating layer, and arrange | positioning several plate-shaped area | regions which differ in refractive index as a 1st structural region in the lower part of an application layer along the film surface direction. And forming a louver structure unformed region in the upper portion of the coating layer

(d) The application layer is further irradiated with a second active energy ray, and a columnar image is formed in the louver structure unformed region with a plurality of columnar bodies having different refractive indices from the media in the media as the second structural region. Process of forming structural regions

 EMBODIMENT OF THE INVENTION Hereinafter, the manufacturing method of the light-diffusion film which is 2nd Embodiment of this invention is demonstrated concretely, referring drawings, centering on a point different from 1st Embodiment.

1. Process (a): Preparation process of the composition for light-diffusion films

Process (a) is a process of preparing the composition for light-diffusion films.

More specifically, it is preferable that the monomer (A) component and the monomer (B) component are stirred under a high temperature condition of 40 to 80 ° C to obtain a uniform mixed liquid.

At the same time, after adding other additives, such as (C) component mentioned later, to a liquid mixture as needed, adding a diluting solvent as needed so that it may become a desired viscosity, stirring until it becomes uniform, It is preferable to obtain the solution of the composition for diffusion films.

Moreover, a monomer (A) component is a monomer component which becomes (A) component which comprises the high refractive index part in a 1st and 2nd structural area | region by superposing | polymerizing, and a monomer (B) component superposes | polymerizes by 1st And a monomer component serving as the component (B) constituting the low refractive index portion in the second structural region.

In addition, the detail about the kind of a monomer (A) component and a monomer (B) component is described as a monomer (A1) and (A2) and (B1) and (B2) component in 1st Embodiment, respectively. Since it is the same, it abbreviate | omits.

(1) Refractive Index of Monomer (A) Component

Moreover, it is preferable to make refractive index of a monomer (A) component into the value within the range of 1.5-1.65.

This reason is, by setting the refractive index of the monomer (A) component to a value within this range, the difference between the refractive index of the portion derived from the component (A) and the portion derived from the component (B) in the louver structure and the column structure. This is because the light diffusion film having a predetermined louver structure and a column structure can be obtained more easily by adjusting more easily.

That is, when the refractive index of the monomer (A) component is less than 1.5, the difference with the refractive index of the monomer (B) component becomes too small, and it may become difficult to obtain a desired incident angle dependency. On the other hand, when the refractive index of the monomer (A) component exceeds a value of 1.65, the difference with the refractive index of the monomer (B) component is greatly changed, but the viscosity is excessively lowered, making compatibility with the monomer (B) component difficult. Because there are cases.

Therefore, it is more preferable to make the refractive index of (A) component into the value within the range of 1.55-1. 6, and it is still more preferable to set it as the value within the range of 1.56-1.59.

In addition, the refractive index of the monomer (A) component mentioned above means the refractive index of the monomer (A) component before hardening by light irradiation.

And the refractive index of a monomer (A) component can be measured according to JISK0062, for example.

(2) Content of monomer (A) component

In addition, it is preferable to make content of a monomer (A) component into the value within the range of 25-400 weight part with respect to 100 weight part of monomer (B) components mentioned later.

The reason for this is that by setting the content of the monomer (A) component to a value within such a range, while irradiating with light while maintaining the mixing property with the monomer (B) component, the copolymerizability of both components is effectively lowered, and the predetermined louver This is because the structure and the column structure can be efficiently formed.

That is, when content of a monomer (A) component is less than 25 weight part, the abundance ratio of (A) component with respect to a monomer (B) component becomes small, and to (A) component in a louver structure and a column structure. It is because the width | variety of the derived part, etc. become excessively small compared with the width | variety of the part derived from (B) component, etc., and it may become difficult to obtain the louver structure and column structure which have favorable incidence angle dependence. Moreover, it is because the length of the louver and columnar object in the longitudinal direction of a light-diffusion film may become inadequate. On the other hand, when content of a monomer (A) component becomes a value exceeding 400 weight part, the abundance ratio of the monomer (A) component with respect to a monomer (B) component increases, and (A) component in a louver structure and a column structure It is because the width | variety of the part derived from, etc. becomes excessively large compared with the width | variety of the part derived from (B) component, etc., On the contrary, it may become difficult to obtain the louver structure and column structure which have favorable incidence angle dependence. Moreover, it is because the length of the louver and columnar object in the longitudinal direction of a light-diffusion film may become inadequate.

Therefore, it is more preferable to make content of a monomer (A) component into the value within the range of 40-300 weight part with respect to 100 weight part of monomer (B) components, and it is still more preferable to set it as the value within the range of 50-200 weight part. Do.

(3) Refractive Index of Monomer (B) Component

Moreover, it is preferable to make the refractive index of a monomer (B) component into the value within the range of 1.4-1.5.

This reason is, by setting the refractive index of the monomer (B) component to a value within such a range, the difference between the refractive index of the portion derived from the component (A) and the portion derived from the component (B) in the louver structure and the column structure. This is because the light diffusion film having a predetermined louver structure and a column structure can be obtained more easily by adjusting more easily.

In other words, if the refractive index of the monomer (B) component is less than 1.4, the difference with the refractive index of the monomer (A) component is greatly changed, but the compatibility with the monomer (A) component is extremely deteriorated, and thus the louver structure and column It is because it may become difficult to form a structure. On the other hand, when the refractive index of the monomer (B) component becomes a value exceeding 1.5, the difference with the refractive index of the monomer (A) component becomes too small, and it may become difficult to obtain desired incident angle dependence.

Therefore, it is more preferable to make the refractive index of a monomer (B) component into the value within the range of 1.45-1.49, and it is still more preferable to set it as the value within the range of 1.46-1.48.

In addition, the refractive index of the above-mentioned monomer (B) component means the refractive index of the monomer (B) component before hardening by light irradiation.

And also in the refractive index of a monomer (B) component, it can measure according to JISK0062, for example.

(4) Content of monomer (B) component

In addition, it is preferable to make content of a monomer (B) component into the value within the range of 20-80 weight% with respect to the total amount (100 weight%) of the composition for light-diffusion films.

The reason for this is that when the content of the monomer (B) component is less than 20% by weight, the abundance ratio of the monomer (B) component to the monomer (A) component is reduced, and the (B) in the louver structure and the column structure It is because the width | variety of the part derived from the component), etc. becomes excessively small compared with the width | variety of the part derived from (A) component, and it becomes difficult to obtain the louver structure and column structure which have favorable incidence angle dependence. . Moreover, it is because the length of the louver and columnar object in the longitudinal direction of a light-diffusion film may become inadequate.

On the other hand, when content of a monomer (B) component exceeds the 80 weight%, the abundance ratio of the monomer (B) component with respect to a monomer (A) component will increase, and (B) in a louver structure and a column structure It is because the width | variety of the part derived from a component, etc. becomes excessively large compared with the width | variety of the part derived from (A) component, and, on the contrary, it may become difficult to obtain the louver structure and column structure which have favorable incidence angle dependence. . Moreover, it is because the length of the louver and columnar object in the longitudinal direction of a light-diffusion film may become inadequate.

Therefore, it is more preferable to make content of a monomer (B) component into the value within the range of 30-70 weight% with respect to the whole amount of the composition for light-diffusion films, and to set it as the value within the range of 40-60 weight%. More preferred.

(5) photopolymerization initiator

Moreover, in the composition for light-diffusion films of this invention, it is preferable to contain a photoinitiator as (C) component as needed.

This reason is because by containing a photoinitiator, the predetermined louver structure and column structure can be formed efficiently, when irradiating an active energy ray with respect to the composition for light-diffusion films.

Here, a photoinitiator means the compound which generate | occur | produces a radical species according to irradiation of active energy rays, such as an ultraviolet-ray.

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 Phenyl ketone, 2-methyl-1- [4- (methylthio) phenyl] -2-morpholino-propane-1-one, 4- (2-hydroxyethoxy) phenyl-2- (hydroxy-2 -Propyl) ketone, benzophenone, p-phenylbenzophenone, 4,4-diethylaminobenzophenone, dichlorobenzophenone, 2-methylanthraquinone, 2-ethylanthraquinone, 2-tert-butylanthraquinone, 2- Aminoanthraquinone, 2-methyl thioxanthone, 2-ethyl thioxanthone, 2-chloro thioxanthone, 2,4-dimethyl thioxanthone, 2,4-diethyl thioxanthone, benzyl dimethyl ketal, acetophenone Dimethyl ketal, p-dimethyla Minbenzoic acid ester, oligo [2-hydroxy-2-methyl-1- [4- (1-methylvinyl) phenyl] propane, etc. are mentioned, You may use these 1 type independently, and 2 or more types You may use in combination.

Moreover, as content in the case of containing a photoinitiator, it is preferable to set it as the value within the range of 0.2-20 weight% with respect to 100 weight% of total amounts of a monomer (A) component and a monomer (B) component, and 0.5-15 weight It is more preferable to set it as the value within the range of%, and it is still more preferable to set it as the value within the range of 1-10 weight%.

(6) other additives

Moreover, other additives can be added suitably in the range which does not impair the effect of this invention.

As another additive, antioxidant, a ultraviolet absorber, an antistatic agent, a polymerization promoter, a polymerization inhibitor, an infrared absorber, a plasticizer, a dilution solvent, a leveling agent, etc. are mentioned, for example.

Moreover, it is preferable to make content of another additive into the value within the range of 0.01-5 weight% generally with respect to 100 weight% of total amounts of a monomer (A) component and a monomer (B) component, and 0.02-3 weight It is more preferable to set it as the value within the range of%, and it is still more preferable to set it as the value within the range of 0.05-2 weight%.

2. Process (b): application process

Step (b) is a step of forming the coating layer 1 by applying the prepared composition for light-diffusion film to the step sheet 2, as shown in Fig. 11 (a).

As a process sheet, any of a plastic film and paper can be used.

Among these, examples of the plastic film include polyester film such as polyethylene terephthalate film, polyolefin film such as polyethylene film and polypropylene film, cellulose film such as triacetyl cellulose film, and polyimide film. .

Moreover, as paper, glassine paper, coated paper, laminated paper, etc. are mentioned, for example.

In addition, about a process sheet, in order to make it easy to peel off the obtained light-diffusion film from a process sheet after photocuring, it is preferable to provide a peeling layer in the application surface side of the composition for light-diffusion films in a process sheet.

Such a peeling layer can be formed using conventionally well-known peeling agents, such as a silicone peeling agent, a fluorine peeling agent, an alkyd peeling agent, and an olefin peeling agent.

Moreover, it is preferable to make thickness of a process sheet into the value within the range of 25-200 micrometers normally.

Moreover, as a method of apply | coating the composition for light-diffusion films on a process sheet, it is conventionally well-known, 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, for example. This can be done according to the method.

Moreover, at this time, it is preferable to make thickness of an application layer into the value within the range of 100-700 micrometers.

3. Step (c): first active energy ray irradiation step

The step (c) is performed by irradiating the first active energy ray to the coating layer, and forming a plurality of plate-like regions having different refractive indices as the first structural region in the lower portion of the coating layer in parallel with each other along the film plane direction. It forms a louver structure area | region and leaves a louver structure unformed area | region in the upper part of an application layer.

That is, as shown to FIG. 11 (b), the active energy ray 50 which consists only of direct light by which the irradiation angle was controlled is irradiated to the application layer 1 formed on the process sheet 2.

More specifically, for example, as shown in Fig. 12 (a), the ultraviolet irradiation device 120 (for example, if it is a commercial item) provided with the cold mirror 122 for condensing on the linear ultraviolet lamp 125 By placing the hot wire cut filter 121 and the light shielding plate 123 on iGraphics Co., Ltd., ECS-4011GX, etc., thereby extracting the active energy ray 50 made up of only the direct light of which the irradiation angle is controlled. Then, the application layer 1 formed on the process sheet 2 is irradiated.

In addition, the linear ultraviolet lamp has a value within the range of -80 to 80 °, preferably on the basis of the direction (0 °) which is perpendicular to the longitudinal direction of the process sheet 2 having the coating layer 1. It is provided so as to be a value in the range of -50 to 50 °, particularly preferably in the range of -30 to 30 °.

The reason for using the linear light source is that the louver structural regions as the first structural regions formed by parallelly arranging the plate-shaped regions having different refractive indices with respect to the film thickness direction at a constant inclination angle are efficiently and stably. It is because it can manufacture.

More specifically, by using the linear light source, it is substantially parallel light when viewed from the axial direction of the linear light source, and non-parallel light can be irradiated when viewed from a direction perpendicular to the axial direction of the linear light source.

At this time, as an irradiation angle of irradiation light, as shown to FIG. 12 (b), irradiation angle (theta) 3 when the angle with respect to the normal line of the surface of the application layer 1 is 0 degrees, is -80 to 80 degrees normally. It is preferable to set it as the value within the range of.

This reason is because when the irradiation angle is set to a value outside the range of -80 to 80 °, the influence of reflection and the like on the surface of the coating layer 1 becomes large, and it may be difficult to form a sufficient louver structure.

Moreover, it is preferable that irradiation angle (theta) 3 has the width (irradiation angle width) (theta) 3 'of 1-80 degrees.

This reason is because when such irradiation angle width | variety (theta) 3 'is set to a value less than 1 degree, the space | interval of a louver structure may become too narrow and it may become difficult to obtain a desired 1st structural area | region. On the other hand, when such irradiation angle width | variety (theta) 3 'becomes a value exceeding 80 degrees, it is because irradiation light may scatter too much and it may become difficult to form a louver structure.

Therefore, it is more preferable to make irradiation angle width | variety (theta) 3 'of irradiation angle (theta) 3 into the value within the range of 2 to 45 degrees, and it is still more preferable to set it to the value within the range of 5 to 20 degrees.

Moreover, although an ultraviolet-ray, an electron beam, etc. are mentioned as irradiation light, it is preferable to use an ultraviolet-ray.

This is because, in the case of an electron beam, since the polymerization rate is very fast, the monomer (A) component and the monomer (B) component cannot be sufficiently phase separated in the polymerization process, and it may be difficult to form a louver structure. to be. On the other hand, when compared with visible light and the like, since the ultraviolet ray is rich in the variation of the ultraviolet curable resin curable according to the irradiation and the photopolymerization initiator that can be used, the selection of the monomer (A) component and the monomer (B) component Because it can widen the width of.

Moreover, as irradiation conditions of an ultraviolet-ray, it is preferable to make illuminance into the value within the range of 0.01-50 mW / cm <^2> .

This is because if the roughness is less than 0.01 mW / cm ² , the louver structure unformed region can be sufficiently formed, but it may be difficult to form the louver structure clearly. On the other hand, when the roughness becomes a value exceeding 50 mW / cm ² , it hardens before the phase separation of the component (A) and the component (B) progresses, on the contrary, it may be difficult to clearly form a louver structure. Because.

Therefore, it is more preferable to make the illumination intensity of an ultraviolet-ray into the value within the range of 0.05-20 mW / cm <^2> , and it is still more preferable to set it as the value within the range which is 0.1-10 mW / cm <^2> .

Moreover, it is preferable to move the coating layer formed on the process sheet at a speed | rate of 0.1-10 m / min, and to let the ultraviolet irradiation part by an ultraviolet irradiation device pass.

This reason is because when such a speed is made into the value below 0.1 m / min, mass productivity may fall excessively. On the other hand, when such a speed becomes a value exceeding 10 m / min, curing of the coating layer, in other words, faster than the formation of the louver structure, the angle of incidence of ultraviolet rays to the coating layer changes, resulting in insufficient formation of the louver structure. Because there are cases.

Therefore, it is more preferable to move the coating layer formed on the process sheet at a speed within the range of 0.2 to 5 m / min, and to pass the ultraviolet irradiation part by the ultraviolet irradiation device, at a speed within the range of 0.5 to 3 m / min. It is more preferable to pass.

4. Step (d): second active energy ray irradiation step

In the step (d), the coating layer is further irradiated with the second active energy ray, and in the louver structure unformed region, a plurality of columnar objects having different refractive indices from the media are placed in the media as the second structural region. It is a process of forming the columnar structural region which consists of.

That is, parallel light with a high degree of parallelism of light rays is irradiated to the application layer formed on the process sheet. In irradiation of the parallel light, you may irradiate directly to a coating layer, It is also preferable to laminate | stack a peeling film on the exposed coating layer surface, and to irradiate over a peeling film. As a peeling film, what has ultraviolet permeability can be suitably selected from what is described in the said process sheet.

Here, the direct light by the linear light source used in the first active energy ray irradiation step has no spread in the direction perpendicular to the axial direction of the linear light source, and is substantially parallel, but is in the axial direction of the linear light source. In the direction parallel to, there is no uniformity in the direction of light and is random.

On the other hand, parallel light in 2nd active energy ray irradiation means the substantially parallel light which does not have spread in the case where the direction of the emitted light is seen from any direction.

More specifically, for example, as shown in FIG. 13 (a), after the light from the point light source 202 is converted into parallel light by the lens 204, the coating layer is irradiated, or FIG. 13 (b). As shown to (c), it is preferable to make the light from the linear light source 206 into parallel light by the assembly 210 of the ordinary thing 208, and to irradiate an application layer.

Therefore, as a specific example of the parallel light irradiation apparatus shown to FIG. 13 (a), the thing which attached the optional uniform exposure adapter to Yamashita Denso Co., Ltd., an ultraviolet spot light source "HYPERCURE'200" is mentioned, for example. .

And it is preferable to make parallelism in parallel light into the value of 10 degrees or less.

The reason for this is that the parallelism is set to a value of 10 ° or less, thereby efficiently and stably producing a column structure region as a second structure region formed by a plurality of columnar products standing up at a constant inclination angle with respect to the film thickness direction. Because you can.

That is, when such parallelism becomes a value exceeding 10 degrees, a column structure may not be formed in some cases.

Therefore, it is more preferable to make the parallelism of parallel light into the value of 5 degrees or less, and it is more preferable to set it as the value of 2 degrees or less.

In addition, although an ultraviolet-ray, an electron beam, etc. are mentioned as irradiation light, it is preferable to use an ultraviolet-ray for the same reason as in the 1st active energy ray irradiation process.

Moreover, as irradiation conditions of an ultraviolet-ray, it is preferable to make illuminance into the value within the range of 0.01-30 mW / cm <^2> .

This is because when the roughness is less than 0.01 mW / cm ² , it may be difficult to form the column structure clearly. On the other hand, when the roughness becomes a value exceeding 30 mW / cm ² , it hardens before phase separation of the component (A) and the component (B) proceeds, and conversely, it may be difficult to form the column structure clearly. Because.

Therefore, it is more preferable to make the illumination intensity of an ultraviolet-ray into the value within the range of 0.05-20 mW / cm <^2> , and it is still more preferable to set it as the value within the range which is 0.1-10 mW / cm <^2> .

In addition, about the moving speed of an application layer and the irradiation angle of irradiation light, it can carry out similarly to a 1st active energy ray irradiation process.

Moreover, it is also preferable to irradiate an active energy ray separately from 1st and 2nd active energy ray irradiation so that the application layer may be the amount of accumulated light which fully hardens.

Since the active energy ray at this time aims at fully hardening an application layer, it is preferable not to use parallel light etc. but to make light which advancing direction is random.

In addition, the light-diffusion film after a photocuring process will be in the state which can be finally used by peeling a process sheet.

[Example]

Hereinafter, the light diffusing film of the present invention and the like will be described in more detail with reference to Examples.

Example 1

1. Synthesis of Monomer (B) Component

2 mol of isophorone diisocyanate (IPDI) as (a) component, and 2-hydroxyethyl as (c) component with respect to 1 mol of polypropylene glycol (PPG) of the weight average molecular weight 9,200 as component (b) in a container. After accommodating 2 mol of methacrylate (HEMA), it was reacted according to a conventional method to obtain a polyetherurethane methacrylate having a weight average molecular weight of 9,900.

In addition, the weight average molecular weight of polypropylene glycol and polyether urethane methacrylate is a polystyrene conversion value measured according to the following conditions by gel permeation chromatography (GPC).

? GPC measuring device: manufactured by Tosoh Corporation, HLC-8020

? GPC column: manufactured by Tosoh Corporation (hereinafter, described in the order of passage)

TSK guard column HXL-H

TSK gel GMHXL (× 2)

TSK gel G2000HXL

 ? Measuring solvent: tetrahydrofuran

 ? Measuring temperature: 40 ℃

2. Preparation of Composition for Light Diffusion Film

Subsequently, o-phenylphenoxy having a weight average molecular weight of 268 represented by the following formula (3) as the monomer (A) component to 100 parts by weight of a polyetherurethane methacrylate having a weight average molecular weight of 9,900 as the obtained monomer (B) component. After adding 100 parts by weight of ethoxyethyl acrylate (manufactured by Shin-Nakamura Chemical Co., Ltd., NK ester # A-LEN-10) and 10 parts by weight of 2-hydroxy-2-methylpropiophenone as the component (C) And heat-mixing were performed on the conditions of 80 degreeC, and the composition for light-diffusion films was obtained. In addition, the refractive indexes of the monomer (A) component and the monomer (B) component were measured according to JIS K0062 using an Abbe refractometer (manufactured by Atago Co., Ltd., product name "Abe refractometer DR-M2", Na light source, wavelength: 589 nm], respectively. 1.58 and 1.46.

3. Application of Composition for Light Diffusion Film

Next, the obtained composition for anisotropic light-diffusion films is apply | coated to the film-form transparent polyethylene terephthalate film (henceforth PET) as a process sheet | seat using an applicator, and the coating layer of 200 micrometers of film thicknesses is applied. Got it.

4. Photocuring of Coating Layer

(1) first ultraviolet irradiation

Subsequently, an ultraviolet irradiation device (ECS-4011GX, manufactured by IGraphics Co., Ltd.) in which a cold mirror for condensing was attached to a linear high-pressure mercury lamp as shown in Fig. 12A was prepared.

Subsequently, when a light shielding plate is provided in a heat ray cut filter image, and the ultraviolet-ray irradiated to the surface of an application layer makes the normal direction of the laminated body which consists of an application layer and PET when viewed from the longitudinal direction of the linear ultraviolet lamp set to 0 degrees. Was set so that the irradiation angle of the ultraviolet rays directly from the lamp (θ3 in FIG. 12 (b)) was -40 °.

At this time, the height of the lamp from the coating layer was set to 500 mm, and the peak illuminance was set to be 1.7 mW / cm ² .

In addition, in order to prevent the reflected light from the light shielding plate or the like from being stray inside the irradiator and affecting the photocuring of the coating layer, a light shielding plate is provided near the conveyor, and only ultraviolet rays emitted directly from the lamp are applied to the coating layer. Was set to be investigated.

Next, the ultraviolet-ray was irradiated along the conveyor, moving the coating layer to the right direction in FIG. 12 (a) at the speed of 0.2 m / min.

(2) second ultraviolet irradiation

Subsequently, after passing through the 1st ultraviolet irradiation process by a linear light source, the exposed surface side of the application layer was laminated by the release film (SP-PET382050 made by Lintec Co., Ltd.) which has the ultraviolet-ray permeability of 38 micrometers in thickness.

Subsequently, by attaching an optional uniform exposure adapter to an ultraviolet spot light source (HYPERCURE 200, manufactured by Yamashita Denso Co., Ltd.), using an apparatus having a parallelism of 2 ° or less, irradiating it over the release film so that the incident angle of parallel light is 40 °. And the light-diffusion film of 200 micrometers of total film thicknesses were obtained.

The average illuminance at that time was 5 mW / cm ² , and the lamp height was 800 mm.

In addition, the film thickness of the light-diffusion film was measured using the static pressure thickness measuring instrument (The Hosei Chemical Co., Ltd. product, Techlock PG-02J).

Moreover, as shown in FIG.14 (a), the obtained light-diffusion film confirmed that the inclination angle of the louver structure was -27 degrees, and the inclination angle of the columnar object was a light-diffusion film with 27 degrees.

Moreover, such FIG. 14 (a) is a schematic diagram which shows the cross section of the film at the time of cut | disconnecting to the surface perpendicular | vertical to the plate-shaped area | region in a louver structure.

The film thickness of the first structural region was 66 µm, and the film thickness of the second structural region was 38 µm.

Furthermore, the cross-sectional photograph of the obtained light-diffusion film is shown to FIG. 15 (a)-(b). (A) is a cross-sectional photograph at the time of cut | disconnecting a film to the surface perpendicular | vertical to the plate-shaped area | region in a louver structure, and FIG. 15 (b) is a surface perpendicular | vertical to the cut surface in FIG. It is a cross-sectional photograph at the time of cut | disconnecting a film.

5. Measure

As shown to Fig.14 (a) using an angle measuring colorimeter (made by Suga Tester Co., Ltd.), it is light from the upper direction of the obtained light-diffusion film with respect to the said film at incident angle (theta) 1 = 60 degrees. Was incident (C light source, viewing angle 2 °).

Next, spread of the diffused light diffused by the light-diffusion film and distribution of the brightness (%) were measured. This measurement result shows the value of the vertical axis | shaft of the scatter diagram shown to FIG. 14 (c) on the horizontal axis of 0 degree.

That is, the value of the horizontal axis represents the range of the spreading angle (°) of the diffused light, and the color of the plot represents the brightness (%) of the diffused light diffused at that angle.

Here, the relationship between the color of the plot and the brightness (%) indicates that the closer the color of the plot is to red, the closer the brightness is to 100%, and the closer the brightness of the plot is to the green, the closer the brightness is to 50%. , The closer the color of the plot is to dark blue, the closer the brightness is to 0%. In addition, it shows in detail in FIG.14 (b).

Furthermore, in order to measure also the spread of the diffused light in the width direction of incident light, and the distribution of the brightness (%), the light-diffusion film is centered around a predetermined point on the surface of the light-diffusion film. The same measurement was performed while rotating in the range of -80 to 80 ° in the same plane. In addition, the angle of such rotation means the angle of rotation at the time of making the angle of the light-diffusion film into 0 degree at the time of the above-mentioned measurement. For example, the measurement result at the time of rotating the light-diffusion film by 20 degrees will show the value of the vertical axis | shaft of the scatter diagram shown to FIG. 14 (c) on the horizontal axis of 20 degrees.

Therefore, in the case of the scatter diagram shown in FIG. 14 (c), for example, a region where the light intensity of 30% or more is distributed is a region surrounded by a dotted line in FIG. 14 (c).

Subsequently, as shown in 14 (d) to (k), the incident angles θ1 for the light diffusing film were respectively 50 °, 40 °, 30 °, 0 °, -30 °, -40 °, -50 °,- It changed to 60 degrees, and spread | dispersed the diffused light and distribution of the brightness (%) was measured similarly to the case of incident angle (theta) 1 = 60 degrees.

6. Results

As shown in Figs. 14 (c) to (k), in the light diffusion film of Example 1, light diffusion is less likely to occur in the range around the incident angle θ1 = 0 ° of incident light, but the incident angle θ1 = 30 to 60 °. In the range, isotropic light diffusion by the column structure region occurs, and anisotropic light diffusion by the louver structure region occurs in the range of the incident angle θ1 = -60? -30 °, and the light diffusion incident angle dependency by the two structure regions. It can be seen that the light diffusion incident angle region can be effectively enlarged by shifting.

EXAMPLE 2

In Example 2, when hardening an application layer, it carried out similarly to Example 1 except having changed (theta) 3 in 1st ultraviolet irradiation to 40 degrees, and the inclination angle of the louver structure is 27 degrees, and the inclination angle of the columnar object is 27 degrees. The light-diffusion film as shown in FIG. 16 which was degrees was obtained.

In addition, spreading of diffused light and distribution of the brightness (%) were measured similarly to Example 1 except having made incident angle (theta) 1 with respect to the light-diffusion film into 25 degrees, 35 degrees, 45 degrees, and 55 degrees, respectively.

As a result, in the light-diffusion film of Example 2, since the light-diffusion incidence angle dependence in the louver structure region and the column structure region almost overlaps, the light-diffusion incidence angle region is in the range of incidence angle θ1 = 25 to 55 °. It became a relatively narrow range.

However, the light-diffusion film of Example 2 confirmed that the uniformity of diffused light was high compared with the comparative examples 1 and 2 mentioned later, and the spread of the diffused light in the width direction of incident light was large compared with the comparative examples 3 and 4. It became.

Example 3

In Example 3, the inclination angle of the louver structure is the same as in Example 1, except that θ3 in the first ultraviolet irradiation is changed to 40 ° and the incident angle of parallel light in the second ultraviolet irradiation is changed to 0 °. The light-diffusion film as shown in FIG. 17 (a) of this inclination angle of 27 degrees and columnar objects was obtained.

In addition, as shown to FIG. 17 (b) (h), except that the incident angles (theta) 1 with respect to a light-diffusion film were 0 degree, 10 degree, 20 degree, 30 degree, 40 degree, 50 degree, 60 degree, respectively, It measured about spread of diffused light and distribution of the brightness (%) similarly to Example 1.

As a result, as shown in Fig. 17 (b)-(h), in the light diffusing film of Example 3, the diffusion of light hardly occurs after the incident angle θ1 = 20 ° of the incident light, but the incident angle = 0-10 °. In the range of, isotropic light diffusion by the column structure region occurs, and anisotropic light diffusion by the louver structure region occurs in the range of the incident angle θ1 = 30 to 60 °, and the light diffusion incident angle dependency by the two structure regions By shifting, it can be seen that the light diffusion incident angle region can be effectively enlarged.

Example 4

In Example 4, the inclination angle of the louver structure is the same as in Example 1, except that θ3 in the first ultraviolet irradiation is changed to 40 ° and the incident angle of parallel light in the second ultraviolet irradiation is changed to 20 °. The light-diffusion film as shown in FIG. 18 (a) of this inclination angle of this 27 degrees and columnar objects was obtained.

In addition, as shown to Fig.18 (b)-(g), Example 1 except having made incident angle (theta) 1 with respect to a light-diffusion film into 5 degrees, 15 degrees, 25 degrees, 35 degrees, 45 degrees, 55 degrees, respectively. Similarly, it measured about spread of diffused light and distribution of the brightness (%).

As a result, as shown in FIGS. 18B and 18G, in the light diffusing film of Example 4, isotropic light diffusion by the column structure region occurs in the range of incident angle θ1 = 5 to 25 ° of incident light. In the range of the incident angle θ1 = 25 to 55 °, anisotropic light diffusion by the louver structure region occurs, and the light diffusion incident angle region is effectively overlapped by partially overlapping the light diffusion incident angle dependency by the two structure regions. It can be seen that it can be enlarged.

Comparative Example 1

In Comparative Example 1, the same procedure as in Example 1 was performed except that the incident angle of the parallel light of the second ultraviolet irradiation was changed to 0 ° without performing the first ultraviolet irradiation. A light-diffusion film having only a column structure having an inclination angle of 0 ° was obtained in the entire region corresponding to the first structural region and the second structural region.

In addition, as shown to Fig.19 (b)-(j), the incident angles (theta) 1 with respect to a light-diffusion film are 20 degrees, 15 degrees, 10 degrees, 5 degrees, 0 degrees, -5 degrees, -10 degrees,-, respectively. The difference of 15 ° and -20 ° was measured for the spread of diffused light and the distribution of brightness (%) in the same manner as in Example 1.

As a result, as shown in Figs. 19 (b) and (j), since the light diffusing film of Comparative Example 1 has only a columnar structure, the light diffusion incident angle region is in the range of θ1 = -15 to 15 °. It became a relatively narrow range.

Moreover, it turns out that the center part of diffused light is especially high in brightness compared with other parts, and the uniformity of diffused light is low.

Comparative Example 2

In Comparative Example 2, as shown in FIG. 20 (a), the same procedure as in Example 1 was performed except that the incident angle of parallel light of the second ultraviolet irradiation was changed to 40 ° without performing the first ultraviolet irradiation. A light-diffusion film having only a column structure having an inclination angle of 27 ° was obtained in the entire region corresponding to the first structural region and the second structural region.

In addition, as shown to FIG. 20 (b) (k), the incident angles (theta) 1 with respect to a light-diffusion film are 15 degrees, 20 degrees, 25 degrees, 30 degrees, 35 degrees, 40 degrees, 45 degrees, 50 degrees, respectively. The difference of 55 degrees and 60 degrees was measured about spread of diffused light and distribution of the brightness (%) similarly to Example 1.

As a result, as shown in Figs. 20 (b) and (k), since the light diffusing film of Comparative Example 2 has only a columnar structure, the light diffusion incident angle region is in the range of θ1 = 25 to 60 °. It became a relatively narrow range.

Moreover, it turns out that the center part of diffused light is especially high in brightness compared with other parts, and the uniformity of diffused light is low.

Comparative Example 3

In Comparative Example 3, except that θ3 of the first ultraviolet irradiation was changed to 0 ° and the second ultraviolet irradiation was not performed, as in Example 1, as shown in FIG. The light-diffusion film which has the louver structure area | region of 0 degree and the louver structure unformed area | region above it was obtained as an inclination-angle as a structure area | region.

In addition, as shown to Fig.21 (b)-(h), the incident angles (theta) 1 with respect to a light-diffusion film were made into 20 degrees, 15 degrees, 10 degrees, 5 degrees, 0 degrees, -5 degrees, and -10 degrees, respectively. Others were measured about spread of diffused light and distribution of the brightness (%) similarly to Example 1.

As a result, as shown in Fig. 21 (b)-(h), the light diffusing film of Comparative Example 3 has only a louver structure, so that the light diffusion angle region is in the range of θ1 = -5 to 15 °. It became a relatively narrow range.

Moreover, it turns out that the anisotropy of diffused light is large and spread of diffused light in the width direction of incident light becomes small.

[Comparative Example 4]

In Comparative Example 4, the first structure is the same as that in Example 1 except that θ3 of the first ultraviolet irradiation is changed to 40 ° and the second ultraviolet irradiation is not performed. As shown in FIG. The light-diffusion film which has a louver structure area | region of 27 degrees as an area | region, and the louver structure unformed area | region above it was obtained.

In addition, as shown to Fig.22 (b)-(i), the incident angles (theta) 1 with respect to a light-diffusion film are 25 degrees, 30 degrees, 35 degrees, 40 degrees, 45 degrees, 50 degrees, 55 degrees, and 60 degrees, respectively. The other one manufactured the light-diffusion film similarly to Example 1.

22 (b) to (i), since the light diffusing film of Comparative Example 4 has only a louver structure, the light diffusion angle region is in a relatively narrow range of θ1 = 30 to 60 °. It became.

Moreover, it turns out that the anisotropy of diffused light is large and spread of diffused light in the width direction of incident light becomes small.

As described above, according to the present invention, according to the present invention, a good incidence is provided by providing a louver structure region for anisotropically diffusing incident light and a column structure region for isotropically diffusing incident light along the film thickness direction. In addition to having angle dependence, a light diffusing film having a wide light diffusing incident angle region was obtained.

Therefore, the light diffusing film of the present invention can be provided not only in the light control film in the reflection type liquid crystal device but also in the viewing angle control film, the viewing angle magnification film, and the projection screen, which will contribute significantly to the high quality thereof. It is expected.

One … 2 coating layer; Process sheet, 10... First structural region (anisotropic light diffusing film), 12... A plate region (high refractive index portion) having a relatively high refractive index, 13. Louver structure region, 13 '... 14 boundary surface of louver structure; A plate region (low refractive index portion) having a relatively low refractive index, 20... Second structural region (isotropic light diffusing film), 22... Columnar, 24... 30 parts other than columnar items; Light diffusing film, 50... Active energy ray; Ultraviolet irradiation device, 121. Hot wire cut filter, 122. Cold mirror, 123... Light shielding plate; UV lamp on board, 100... Reflective liquid crystal display, 101. Polarizer 102. Retardation plate, 103. Light diffusion plate, 104. Glass plate, 105. Color filter 106. Liquid crystal, 107... Mirror reflector, 108. Glass plate, 110... Liquid crystal cell, 202. Point light source, 204... Lens, 206. Ultraviolet ray lamp, 208... Ordinary material, 210... A collection of ordinary products

Claims (9)

A light diffusing film having a first structural region for anisotropically diffusing incident light and a second structural region for isotropically diffusing incident light,
The first structural region is a louver structural region formed by arranging a plurality of plate-shaped regions having different refractive indices in parallel along the film plane direction,
The second structure region is a column structure region formed by standing a plurality of columnar objects having a refractive index different from that of the medium in the medium. The method of claim 1,
In the first structural region, the width of the plate region having different refractive indices is set to a value within the range of 0.1 to 15 µm, respectively, and the plate region is arranged in parallel with a constant inclination angle with respect to the film thickness direction. Light diffusion film characterized by. The method of claim 1,
In the first structural region, the main component of the plate-shaped region having a high refractive index is a polymer of (meth) acrylic acid ester containing a plurality of aromatic rings among the plate-shaped regions having different refractive indices, and the main component of the plate-shaped region having a low refractive index is It is a polymer of urethane (meth) acrylate, The light-diffusion film characterized by the above-mentioned. The method of claim 1,
The thickness of the said 1st structural region is made into the value within the range of 5-495 micrometers, The light-diffusion film characterized by the above-mentioned. The method of claim 1,
In the said 2nd structural area | region, while making the maximum diameter in the cross section of the said columnar object into the value within the range of 0.1-15 micrometers, the distance between columnar objects is made into the value within the range of 0.1-15 micrometers, A light-diffusion film characterized by forming a plurality of columnar objects at a predetermined inclination angle with respect to the film thickness direction. The method of claim 1,
In the second structural region, the main component of the columnar product is (meth) acrylic acid ester containing a plurality of aromatic rings, and the main component of the medium is urethane (meth) acrylate. The method of claim 1,
The thickness of the said 2nd structural area | region is made into the value within the range of 5-495 micrometers, The light-diffusion film characterized by the above-mentioned. A method of manufacturing a light-diffusion film having a first structural region for anisotropically diffusing incident light and a second structural region for isotropically diffusing incident light,
The manufacturing method of the light-diffusion film containing following process (a)-(d).
(a) process of preparing the composition for light-diffusion films
(b) Process of apply | coating the said composition for light-diffusion films with respect to a process sheet, and forming an application layer
(c) Louver formed by irradiating a first active energy ray with respect to the said application layer, and arrange | positioning several plate-shaped area | regions from which the refractive index as a 1st structural area | region differs in parallel to each other along the film surface direction below the said application layer. Forming a structural region and leaving the louver structure unformed region on the upper portion of the coating layer.
(d) further irradiating a second active energy ray to the coating layer, and forming a plurality of columnar objects having a refractive index different from that of the medium in the medium as the second structural region in the louver structure unformed region. Process of forming columnar structural region The method of claim 8,
As said 2nd active energy ray irradiation, parallel light with a parallelism 10 value or less is irradiated, The manufacturing method of the light-diffusion film characterized by the above-mentioned.

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