TWI537611B - Light diffusion film and producing method for the same - Google Patents

Description

Light diffusion film and method for manufacturing light diffusion film

The present invention is a method for producing a light diffusion film and a light diffusion film. In particular, by including a louver structure region that anisotropically diffuses incident light and a column structure region that diffuses incident light isotropically, it has a good incident angle dependency in light transmission and diffusion, and light diffusion incidence A light diffusion film having a wide angle region and a method of manufacturing the light diffusion film.

Conventionally, in a liquid crystal display device, light emitted from a light source (internal light source) provided inside the device can be used to recognize a given image.

However, in recent years, with the spread of mobile phones, car televisions, and the like, the chance of viewing a liquid crystal display screen outdoors has increased, and the accompanying light intensity from the internal light source is not suitable for external light and it is difficult to recognize a given picture. problem.

In addition, in mobile applications such as mobile phones, since the power consumption of the internal light source of the liquid crystal display device accounts for a large proportion of the total power consumption, when the internal light source is used in a large amount, the battery life of the battery becomes short. problem.

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

In the case of the reflective liquid crystal display device, since the external light is partially used as a light source, the stronger the external light, the more vivid 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 into the inside of the liquid crystal display device, and to effectively utilize the external light as one of the light sources, it has been proposed to efficiently perform light diffusion. A scheme of a light diffusion film (for example, Patent Document 1).

More specifically, in Patent Document 1, as shown in FIGS. 23(a) to 23(b), a liquid crystal cell having a liquid crystal layer 1105 interposed between the upper substrate 1103 and the lower substrate 1107 is disclosed. A light reflecting plate 1110 provided on the lower substrate 1107 side and a liquid crystal device 1112 provided on a light control plate (light diffusion film) 1108 provided between the liquid crystal layer 1105 and the light reflecting plate 1110.

Further, a light control panel 1108 for selectively scattering light incident at a given angle and transmitting light incident at an angle other than a given angle is provided, the light control panel 1108 being disposed in the liquid crystal cell in the following manner That is, the scattering axis direction 1121 obtained by selectively scattering the direction of the light incident at a given angle onto the surface of the light control plate 1108 is substantially in the direction of the 6 o'clock direction in the plane of the liquid crystal cell.

Here, as a light diffusion film used in a reflective liquid crystal display device, a light diffusion film in which an active energy ray is irradiated to a specific photocurable composition using a linear light source is disclosed. A plate-like region having a high refractive index and a plate-like region having a low refractive index are alternately arranged in parallel in the plane direction, and a louver structure region is formed in the film (see, for example, Patent Documents 2 to 3).

That is, in Patent Document 2, there has been disclosed a light control film which irradiates ultraviolet rays in a specific direction to a film-like composition containing a plurality of compounds having a polymerizable carbon-carbon double bond to cure the composition. A light control film obtained by selectively scattering only incident light (light diffusion film) of a specific angular range, characterized in that at least one compound contained in the composition has a plurality of aromatic rings and one in the molecule A compound of a polymerizable carbon-carbon double bond.

Further, Patent Document 3 discloses a photocurable composition comprising a fluorene compound (A) having a polymerizable carbon-carbon double bond in a molecule, a refractive index, and a lanthanide system. A cationically polymerizable compound (B) having a different compound (A) and a cationic photopolymerization initiator (C) are disclosed, and a light control film obtained by curing the same is disclosed.

On the other hand, as another type of light-diffusing film used in a reflective liquid crystal device, a light-diffusing film has been disclosed, that is, by irradiating a specific photocurable composition as an active energy ray as a parallel light, Further, in the film thickness direction of the film, a column structure region in which a plurality of pillars having different refractive indices from the medium are formed is formed in a medium (see, for example, Patent Documents 4 to 6).

That is, Patent Document 4 discloses a method for producing a diffusion medium in which a composition containing a photocurable compound is provided in a sheet form, and the sheet is irradiated with parallel rays in a given direction P to cure the composition. A method for producing a diffusion medium (light diffusion film) in which an aggregate of a plurality of rod-shaped solidified regions extending in parallel in the direction P is formed, wherein a linear light source and a sheet are sandwiched in parallel with the direction P A collection of configured cartridges through which light is illuminated.

In addition, in the ninth aspect of the invention, a light control film manufacturing apparatus is disclosed in which at least one of the photocurable resin composition and the linear light source is moved while the linear light source is disposed to face the photocurable resin composition. A device for producing a light control film (light diffusion film) by irradiating light from a linear light source to form a light control resin composition film, wherein the axial direction of the linear light source intersects with the moving direction and faces each other a plurality of thin plate-shaped light-shielding members are disposed at a predetermined interval in a direction substantially perpendicular to the moving direction, and a side of the light-shielding member facing the photocurable resin composition film is disposed in the same direction as the moving direction The photocurable resin composition is between the linear light source.

Further, Patent Document 6 discloses a reflective projection screen including a diffusion layer (diffusion film) that covers a plate surface that faces upward as a light absorption surface and a reflection surface that faces downward as a reflection. The Fresnel surface of the planar linear Fresnel member is disposed and has a diffusion characteristic that does not diffuse incident light larger than a given angle, and the diffusion layer is generated by the first light irradiation step and the second light irradiation step, The first light irradiation step is a step of irradiating the photocurable resin composition in a given direction with a photomask having a light passage region and a light non-passage region, and curing the irradiated portion to an incomplete cured state. In the second light irradiation step, the photomask is removed, and the photocurable resin is irradiated with parallel light having a substantially constant light intensity distribution to complete the curing of the photocurable composition, and a phase separation structure is provided in the film. The phase separation structure has a matrix comprising a substrate of a photocurable composition and a plurality of columnar structures having a refractive index extending in the direction of irradiation of the parallel light in the matrix different from the matrix

Patent literature

Patent Document 1 Japanese Patent No. 3480260 (Application Patent Drawing, Drawing, etc.)

Patent Document 2 Japanese Laid-Open Patent Publication No. 2006-350290 (Application No. Patent Specification, Drawings, etc.)

Patent Document 3 Japanese Laid-Open Patent Publication No. 2008-239757 (Patent Application, Drawing, etc.)

Patent Document 4 Japanese Patent No. 4,095,573 (Application Patent Range, Drawing, etc.)

Patent Document 5 Japanese Laid-Open Patent Publication No. 2009-173018 (Application No. Patent Specification, Drawings, etc.)

Patent Document 6 Japanese Laid-Open Patent Publication No. 2008-256930 (Patent Application, Drawing, etc.)

However, in the light-diffusing film having the louver structure region disclosed in Patent Documents 1 to 3, an incident angle region (hereinafter sometimes referred to as a light diffusion incident angle region) in which incident light capable of light diffusion is formed is narrowed, and diffused light is diffused. The opening angle is also narrowed.

Further, in the light-diffusing film having the columnar structure region disclosed in Patent Documents 4 to 5, since light diffusion film having a louver structure region is liable to be uneven in reflection of light in the film, incident light is generated. The fluctuation of the diffusion characteristics caused by the incident angle is large, and it becomes difficult to exhibit a good incident angle dependency.

Therefore, the inventors of the present invention conducted intensive studies in view of the above-described circumstances, and as a result, found that a louver structure region for anisotropically diffusing incident light and a isotropic property for incident light are provided in the film. The ground diffusion region of the column structure, that is, a light diffusion film having a good incident angle dependency and a wide light diffusion incident angle region can be obtained, thereby completing the present invention.

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

According to the present invention, there is provided a light diffusing film having a first structural region for anisotropically diffusing incident light and a second structural region for isotropically diffusing incident light, characterized in that The structural region is a louver structure region in which a plurality of plate-like regions having different refractive indices are alternately arranged in parallel along the film surface direction, and the second structural region is a plurality of columns in which a refractive index is different from the medium in the medium. The column structure area is formed to solve the above problems.

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

Therefore, by repeating the incident angle dependency of each structural region, it is possible to suppress not only fluctuations in the diffusion characteristics, but also good incident angle dependence, and it is also possible to effectively expand the opening angle of the diffused light.

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

In addition, the "film surface direction" in the present invention means the x-y plane direction when the film thickness direction is the z-axis.

In the present invention, the term "light-diffusing incident angle region" refers to an angular range of incident light corresponding to the emitted diffused light when the angle of incident light from the point light source is changed with respect to the anisotropic light-diffusing film. . Details of the light diffusion incident angle region will be described later.

In addition, the term "good incident angle dependency" means that the difference between the incident angle region (light diffusing incident angle region) with respect to the film in which the light of the incident light is diffused and the other incident angle region where no light diffusion occurs is possible. Clear control.

Further, the term "anisotropic" in the present invention means that the shape in which the diffused light is broadened has anisotropy, and the "isotropic" means that the shape in which the diffused light is broadened has isotropy. This will also be described later.

Further, in the case of constituting the light-diffusing film of the present invention, it is preferable that the width of the plate-like region having a different refractive index is set to a value in the range of 0.1 to 15 μm in the first structural region, and the plate-like region is opposed to each other. They are arranged in parallel at a certain inclination angle in the film thickness direction.

According to this configuration, the incident light can be 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 opening angle of the diffused light can be further improved.

Further, in the case of constituting the light-diffusing film of the present invention, it is preferable that the main component of the plate-like region having a high refractive index among the plate-like regions having different refractive indices in the first structural region contains a plurality of aromatic rings (methyl) The acrylate polymer, the main component of the plate-like region having a low refractive index, is a polymer of urethane (meth) acrylate.

According to this configuration, not only the louver structure as the first structural region but also the angle of incidence dependence of the first structural region and the opening angle of the diffused light can be further improved.

Further, in the case of constituting the light-diffusing film of the present invention, the thickness of the first structural region is preferably in the range of 5 to 495 μm.

With such a configuration, the length of the louver structure along the film thickness direction can be stably ensured, and the incident light can be more stably reflected in the louver structure region as the first structural region, thereby further increasing the incident angle from the first structural region. Dependence and the angle of opening of the diffused light.

Further, in the case of constituting the light-diffusing film of the present invention, it is preferable that the maximum diameter of the cross section of the pillar is set to a value in the range of 0.1 to 15 μm in the second structural region, and the distance between the pillars is set. It is a value in the range of 0.1 to 15 μm, and a plurality of pillars are arranged at a certain inclination angle with respect to the film thickness direction.

According to this configuration, the incident light can be more stably reflected in the column structure region as the second structural region, and the incident angle dependency derived from the second structural region and the opening angle of the diffused light can be further improved.

Further, in the case of constituting the light-diffusing film of the present invention, it is preferable that in the second structural region, the main component of the column contains a polymer of a plurality of (meth) acrylates of an aromatic ring, and the main component of the vehicle A polymer of urethane (meth) acrylate.

According to this configuration, not only the column structure as the second structure region but also the angle of incidence dependence of the second structure region and the opening angle of the diffused light can be further improved.

Further, in the case of constituting the light-diffusing film of the present invention, the thickness of the second structural region is preferably in the range of 5 to 495 μm.

With such a configuration, it is possible to stably ensure the length of the pillar along the film thickness direction, and to more stably reflect the incident light in the column structure region as the second structural region, further improving the incidence from the second structural region. Angle dependence and opening angle of diffused light.

Further, another aspect of the present invention provides a method of manufacturing a light diffusion film having a first structure region for anisotropically diffusing incident light, and a second structure for isotropically diffusing incident light. A method of producing a light diffusing film in a region, comprising the following steps (a) to (d).

(a) a step of preparing a composition for a light diffusion film;

(b) a step of applying a composition for a light-diffusing film onto an engineering sheet to form a coating layer;

(c) irradiating the coating layer with the first active energy ray, 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, which are alternately arranged in parallel along the film surface direction. a louver structure region, and a step of remaining a louver structure region remaining in an upper portion of the coating layer;

(d) further irradiating the coating layer with the second active energy ray, and forming a plurality of pillars having a refractive index different from the medium in the medium as the second structural region in the region where the louver structure is not formed The step of the columnar structure area.

That is, in the case of the method for producing a light-diffusing film of the present invention, after the louver structure region as the first structural region is formed by the first active energy ray irradiation, the second active energy ray may be irradiated by the second active energy ray. A pillar structure region as a second structural region is formed in an unformed region above a structural region.

Therefore, it is possible to efficiently and stably manufacture a light-diffusing film including a louver structure region as a first structural region and a pillar structure region as a second structural region in the film thickness direction in a single film.

Further, in carrying out the method for producing a light-diffusing film of the present invention, it is preferred to irradiate the second active energy ray as a parallel light having a parallelism of 10 or less.

By doing so, it is possible to efficiently and stably manufacture the column structure region as the second structural region in which a plurality of pillars are formed at a certain inclination angle with respect to the film thickness direction.

[First Embodiment]

A first embodiment of the present invention is a light diffusing film having a first structural region for anisotropically diffusing incident light, and a second structural region for isotropically diffusing incident light, characterized in that The first structural region is a louver structure region in which a plurality of plate-like regions having different refractive indices are alternately arranged in parallel along the film surface direction, and the second structural region is different in the medium from the medium. A column structure area formed by a plurality of pillars.

Hereinafter, a first embodiment of the present invention will be specifically described with reference to the accompanying drawings.

Basic principle

Next, the basic principle of light diffusion by the louver structure and light diffusion by the column structure in the light diffusion film will be separately described.

(1) Light diffusion by means of louver structure

Fig. 1(a) shows a top view (top view) of a first structural region 10 having only a louver structure region for anisotropically diffusing incident light, and Fig. 1(b), Fig. 1 (a) The first structural region 10 shown is cut in the vertical direction along the dashed line AA, showing a cross-sectional view of the first structural region 10 when the cutting surface is viewed from the direction of the arrow.

Further, the term "anisotropic" as used in the present invention means a property in which the diffused light is diffused and the film is diffused by a film as shown in Figs. 2(a) to 2(b). The degree of diffusion of the light in the parallel plane (the shape of the spread of the diffused light) has different properties with the direction in the same plane.

More specifically, in the case of the first structural region 10, the light is mainly diffused in a direction perpendicular to the direction of the louver structure extending along the film surface direction in a plane parallel to the diffused outgoing light. Therefore, the shape of the spread of the diffused light is approximately elliptical.

Further, as shown in the plan view of Fig. 1(a), the first structural region 10 has a plate-like region 12 having a relatively high refractive index and a plate-like region 14 having a relatively low refractive index which are alternately arranged in parallel along the film surface direction. The louver structure 13 is also extended at the same time.

Further, as shown in the cross-sectional view of Fig. 1(b), the plate-like region 12 having a higher refractive index and the plate-like region 14 having a lower refractive index have a given thickness, respectively, in the vertical direction of the first structural region 10. Maintain a state of alternately parallel configuration.

From this, it can be estimated that, as shown in FIGS. 2( a ) to ( b ), when the incident angle is within the light diffusion incident angle region, the incident light is diffused by the first structural region 10 .

That is, it can be presumed that, as shown in FIG. 1(b), the incident angle of the incident light with respect to the first structural region 10 and the interface 13 of the louver structure 13 are parallel to a value within a given angular range, That is, in the case where the light diffuses the value in the incident angle region, the incident light (52, 54) passes through the plate-like region 12 having a high refractive index in the louver structure along the film thickness direction while changing the direction. The direction of travel of the light on the light-emitting side is different.

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

Moreover, the light diffusion incident angle region is as shown in Figs. 2(a) to (b), Figs. 6(a) to (b), and Figs. 7(a) to (b), and is a louver structure in the light diffusion film or The refractive index difference, the inclination angle, and the like of the column structure are determined by the light diffusion film.

Further, a change in the direction of the incident light in the plate-like region 12 having a high refractive index in the louver structure is abruptly refractive index type in which the direction is changed linearly by the total reflection as shown in Fig. 1(b). In addition to the case, a case of a graded refractive index type in which a direction changes in a curved shape may be considered.

On the other hand, in the case where the incident angle of the incident light with respect to the first structural region 10 is out of the light diffusion incident angle region, it can be presumed that the incident light 56 is not diffused by the first structural region 10, but is unchanged as it is. Through the first structural region 10 (56').

According to the above mechanism, the first structure region 10 having the louver structure 13 can exhibit an incident angle dependency in light transmission and diffusion, for example, as shown in FIGS. 2(a) to 2(b).

Further, as shown in FIGS. 2( a ) to 2 ( b ), when the incident angle of the incident light is included in the light diffusion incident angle region, the first structural region may be on the light emitting surface side even when the incident angle is different. Perform substantially the same light diffusion.

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

Here, the relationship between the incident angle of the incident light with respect to the first structural region and the opening angle of the diffused light diffused by the first structural region will be described with reference to FIG. 3(a).

That is, in Fig. 3(a), an opening angle (°) of incident light with respect to the first structural region is taken in the horizontal axis, and an opening of diffused light diffused by the first structural region is taken in the vertical axis. Characteristic curve of angle (°).

Further, as shown in FIGS. 4(a) to 4(c), the incident angle θ1 is an angle (°) when the angle perpendicular to the first structural region 10 is set to 0°.

More specifically, as described above, since the component of the incident light that participates in the anisotropic light diffusion is mainly a component perpendicular to the direction of the louver structure extending in the film surface direction, the incident light referred to in the present invention is " In the case of the incident angle θ1", it means the incident angle of a component perpendicular to the direction of the louver structure extending in the film surface direction. In addition, at this time, the incident angle θ1 is an angle (°) when the angle with respect to the normal to the incident side surface of the light diffusion film is 0°.

Further, the opening angle θ2 of the diffused light, as indicated by the literal surface, refers to the opening angle (°) of the diffused light.

Further, the larger the opening angle of the diffused light, the more the light incident at the incident angle at this time is effectively diffused by the first structural region.

On the contrary, the smaller the opening angle of the diffused light, the more the light incident at the incident angle at this time passes through the first structural region as it is, and is not pre-diffused.

Further, a specific measurement method of the opening angle of the diffused light is described in the examples.

That is, it can be understood from the characteristic curve shown in FIG. 3(a) that, if it is the first structural region, the degree of light transmission and diffusion is greatly different due to the difference in the incident angle, and the light can be diffused to the incident angle. The area is clearly separated from the angle of incidence outside it.

On the other hand, in the case of a film that does not have an incident angle dependency, as shown in FIG. 3(b), the change in the incident angle does not have a clear influence on the degree of light transmission and diffusion, and the light diffusion incidence cannot be determined. Angle area.

(2) Light diffusion by means of column structure

In addition, in FIG. 5(a), a top view (top view) of the second structural region 20 having only the column structure region and for isotropically diffusing the incident light is shown, and in FIG. 5(b), FIG. The second structural region 20 shown in Fig. 5(a) is cut in the vertical direction along the broken line AA, and shows a cross-sectional view of the second structural region 20 when the cutting surface is viewed from the direction of the arrow.

Further, the term "isotropic" as used in the present invention means a property in which, when, for example, the light is diffused by a film as shown in Figs. 6(a) to (b), the diffused outgoing light is combined. The degree of diffusion of the light in the plane parallel to the film (the shape in which the diffused light is broadened) does not change with the direction in the same plane.

More specifically, in the case of the second structural region 20, the degree of diffusion of the diffused outgoing light is rounded in a plane parallel to the film.

Here, as shown in the plan view of FIG. 5(a), the second structural region 20 has a pillar structure (22, 24) including a pillar 22 having a relatively high refractive index and a medium 24 having a relatively low refractive index.

Further, as shown in the cross-sectional view of FIG. 5(b), in the vertical direction of the second structural region 20, the pillars 22 having a higher refractive index and the medium 24 having a lower refractive index are respectively formed to have a given width. The state of alternating ground configuration.

From this, it can be estimated that, as shown in FIGS. 6( a ) to 6 ( b ), when the incident angle is within the light diffusion incident angle region, the incident light is diffused by the second structural region 20 .

That is, it can be presumed that, as shown in FIG. 5(b), the incident angle of the incident light with respect to the second structural region 20 and the interface 23 of the pillar structure 23 are parallel to a value within a given angular range, That is, in the case where the light diffuses the value in the incident angle region, the incident light (62, 64) passes through the high refractive index pillar 22 in the column structure along the film thickness direction while changing the direction, and The direction of travel of the light on the light-emitting side is different.

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

Further, a change in the direction of the incident light in the column 22 having a high refractive index in the column structure is abruptly refractive index type in which the direction is changed linearly by the total reflection as shown in FIG. 5(b). In addition to the case, a case of a graded refractive index type in which a direction changes in a curved shape may be considered.

On the other hand, it can be presumed that, in the case where the incident angle of the incident light with respect to the second structural region 20 is out of the light diffusion incident angle region, the incident light 66 is not diffused by the second structural region 20, and is transmitted unchanged as it is. Two structural regions 20 (66').

According to the above mechanism, the second structure region 20 including the pillar structure 23 can exhibit an incident angle dependency in light transmission and diffusion, for example, as shown in FIGS. 6(a) to 6(b).

Further, since the relationship between the incident angle of the incident light with respect to the second structural region and the angle of the diffused light diffused by the second structural region is the same as that of the first structural region described above, the description thereof will be omitted.

2. Basic composition

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

As shown in FIGS. 7(a) to 7(b), the light diffusion film 30 of the present invention is characterized in that it has a louver structure region (first structure region) 10 for anisotropically diffusing incident light, and is used for The column structure region (second structure region) 20 that isotropically diffused incident light is preferably configured to include the structural regions in the vertical direction in the film thickness direction.

Therefore, in the case of the light-diffusing film of the present invention, for example, by repeating the incident angle dependency of the first and second structural regions as shown in Fig. 7(a), it is possible to suppress not only the fluctuation of the diffusion characteristics but also the fluctuation of the diffusion characteristics. Good angle of incidence dependence, and the angle of the opening of the diffused light can be effectively broadened.

Further, in the case of the light-diffusing film of the present invention, for example, by shifting the incident angle dependency of the first and second structural regions as shown in FIG. 7(b), it is possible to broadly and efficiently widen the light. Diffusion angle of incidence area.

3. The first structural area

The light-diffusing film of the present invention is characterized in that a first structural region for anisotropically diffusing incident light has a plurality of plate-like regions having different refractive indices, that is, a plate-like region having a relatively high refractive index ( The high refractive index portion and the louver structure region in which the plate-like regions (low refractive index portions) having a relatively low refractive index are alternately arranged in parallel along the film surface direction.

Hereinafter, the first structural region will be specifically described.

(1) Refractive index

Further, in the first structural region, it is preferable that the difference in refractive index between the plate-like 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 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, incident light can be stably reflected in the louver structure region as the first structural region, and the incident angle dependency derived from the first structural region can be further improved. Sexual and diffuse light opening angle.

More specifically, if the difference in refractive index is less than 0.01, the angle of the total reflection of the incident light in the louver structure is narrowed, so that the incident angle dependency is excessively lowered and diffused. The case where the opening angle of the light is excessively narrowed.

Therefore, it is preferable that the difference in refractive index between the plate-like regions having different refractive indices in the first structural region is 0.05 or more, and particularly preferably 0.1 or more.

Further, it is considered that the difference between the refractive index of the high refractive index portion and the refractive index of the low refractive index portion is preferably as large as possible. However, from the viewpoint of selecting a material capable of forming a louver structure, about 0.3 is an upper limit.

Further, in the first structural region, the refractive index of the plate-like region (high refractive index portion) having a relatively high refractive index is preferably in the range of 1.5 to 1.7.

The reason is that if the refractive index of the high refractive index portion is less than 1.5, the difference from the low refractive index portion is too small, and it may be difficult to obtain a desired louver structure.

On the other hand, when the refractive index of the high refractive index portion is more than 1.7, the compatibility between the material substances in the composition for a light-diffusing film may be excessively lowered.

Therefore, it is preferable to set the refractive index of the high refractive index portion of the first structural region to a value in the range of 1.52 to 1.65, and it is preferably set to a value within the range of 1.55 to 1.6.

Further, the refractive index of the high refractive index portion can be measured in accordance with JIS K0062.

Further, in the first structural region, it is preferable to set the refractive index of the plate-like region (low refractive index portion) having a relatively low refractive index to a value in the range of 1.4 to 1.5.

The reason for this is that if the refractive index of the low refractive index portion is less than 1.4, the rigidity of the obtained light diffusion film may be lowered.

On the other hand, when the refractive index of the refractive index portion exceeds 1.5, the difference in refractive index from the high refractive index portion becomes too small, and it may be difficult to obtain a desired louver.

Therefore, it is preferable to set the refractive index of the low refractive index portion of the first structural region to a value in the range of 1.42 to 1.48, and it is particularly preferable to set the value in the range of 1.44 to 1.46.

Further, the refractive index of the low refractive index portion can be measured in accordance with, for example, JIS K0062.

(2) width

Further, as shown in FIGS. 8(a) to 8(b), in the first structural region, it is preferable to set the widths (S1, S2) of the high refractive index portion 12 and the low refractive index portion 14 having different refractive indices, respectively. A value in the range of 0.1 to 15 μm.

The reason for this is that by setting the width of the plate-like regions to a value in the range of 0.1 to 15 μm, it is possible to more stably reflect the incident light in the louver structure region as the first structural region, thereby further increasing the origin. The angle of incidence dependence of the first structural region and the opening angle of the diffused light.

That is, if the width of the plate-like region is less than 0.1 μm, the light diffusibility may be difficult to display regardless of the incident angle of the incident light. On the other hand, when the width is a value exceeding 15 μm, the light traveling straight in the louver structure increases, and the uniformity of light diffusion may be deteriorated.

Therefore, it is preferable that the width of the plate-like region having a different refractive index is set to a value in the range of 0.5 to 10 μm in the first structural region, and it is particularly preferable to set the value in a range of 1 to 5 μm.

Further, the width, length, and the like of the plate-like region constituting the louver can be calculated by observation with an optical digital microscope.

(3) length

Further, as shown in FIGS. 8(a) to 8(b), in the first structural region, it is preferable that the lengths L1 of the high refractive index portion 12 and the low refractive index portion 14 having different refractive indices are set to 5 to 495 μm, respectively. The value in the range.

The reason is that if the length is less than 5 μm, the length of the louver structure is particularly insufficient, and the incident light traveling straight in the louver structure increases, so that it is difficult to obtain sufficient incident angle dependency and diffused light. The case of the opening angle.

On the other hand, when the length is more than 495 μm, when the composition for a light-diffusion film is irradiated with an active energy ray to form a louver structure, the louver structure formed at the beginning causes the direction of photopolymerization to diffuse. It is difficult to form the desired louver structure.

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

Further, as shown in FIG. 8(b), the louver structure may not be formed in the first structural region to the lower end portion in the film thickness direction.

In this case, the width L2 of the lower end portion of the louver structure is not determined by the thickness of the first structure region, but in general, it is preferably in the range of 0 to 100 μm, preferably in the range of 0 to 50 μm. The value is particularly preferably in the range of 0 to 5 μm.

(4) Tilt angle

Further, as shown in Figs. 8(a) to 8(b), in the first structural region, it is preferable that the high refractive index portion 12 and the low refractive index portion 14 having different refractive indices have a certain inclination angle θa with respect to the film thickness direction. extend.

The reason is that, by setting the inclination angle of the plate-like region to be constant, it is possible to more stably reflect the incident light in the louver structure region as the first structural region, thereby further increasing the incident angle from the first structural region. Dependence and the angle of opening of the diffused light.

Further, as shown in Fig. 8(c), it is preferable that the louver structure is curved.

The reason is because the louver structure is curved, that is, the incident light traveling straight in the louver structure can be reduced, and the uniformity of light diffusion can be improved.

Further, such a curved louver structure can be obtained by irradiating light while changing the irradiation angle of the irradiation light when the first active energy ray irradiation described in the second embodiment is performed, but it is also considerably dependent on the formation of the louver. The type of material of the structure.

In addition, θa is the inclination angle of the plate-like region when the angle with respect to the normal to the film surface is 0° measured in the cross section when the film is cut perpendicular to the louver structure extending in the film surface direction. (°).

More specifically, as shown in FIG. 8, it means the angle of the narrow side of the angle formed by the normal line of the film surface of the incident light irradiation side and the plate-shaped area. Further, as shown in FIG. 8(a), the inclination angle when the louver is inclined to the left side is used as a reference, and the inclination angle when the louver is inclined to the left side is represented by a negative value.

(5) Thickness

Further, it is preferable to set the thickness of the first structural region to a value within a range of 5 to 495 μm.

The reason is that, by setting the thickness of the first structural region to a value within the range, the length of the louver structure along the film thickness direction can be stably ensured, and the louver structure region as the first structural region is more The incident light is stably reflected, and the angle of incidence dependence from the first structural region and the opening angle of the diffused light are further improved.

That is, if the thickness of the first structural region is less than 5 μm, the length of the louver structure may be insufficient, and the incident light traveling straight in the louver structure may increase, so that it is difficult to obtain sufficient incident angle dependency and The case of diffusing the opening angle of light.

On the other hand, when the thickness of the first structural region is more than 495 μm, when the composition for a light-diffusing film is irradiated with an active energy ray to form a louver structure, the louver structure formed at an initial stage causes photopolymerization to proceed. The direction is diffused, so that it is difficult to form the desired louver structure.

Therefore, it is preferable to set the thickness of the first structural region to a value in the range of 40 to 310 μm, and it is particularly preferable to set the value in the range of 95 to 255 μm.

(6) Material substances

(6)-1 high refractive index portion

Further, in the first structural region, the type of the material substance for constituting the high refractive index portion of the plate-like region having a relatively high refractive index among the plate-like regions having different refractive indices is not particularly limited, but it is preferably The main component is a polymer of a (meth) acrylate containing a plurality of aromatic rings.

The reason for this is that, in the case of the material material, not only the louver structure as the first structural region but also the angle of incidence dependence of the first structural region and the opening angle of the diffused light can be further improved.

In other words, it is presumed that when the main component of the high refractive index portion (hereinafter sometimes referred to as (A1) component) is a specific (meth) acrylate polymer, when the first structural region is formed, The polymerization rate of the monomer component (hereinafter sometimes referred to as the monomer (A1) component) which is a component (A1) by polymerization is higher than the main component of the low refractive index component which is low in refractive index which will be described later by polymerization (hereinafter, The monomer component (hereinafter sometimes referred to as the monomer (B1) component) referred to as the (B1) component) has a high polymerization rate.

Further, it can be presumed that a given difference is produced in the polymerization rate between the monomer components, and it is possible to suppress uniform copolymerization between the two monomer components, and more specifically, to reduce the compatibility of the two monomer components to The range is such that the copolymerization between the two monomer components is effectively reduced.

As a result, it is possible to effectively form a louver structure in which the (A1) component and the (B1) component are alternately extended in the film in-plane direction by irradiation with an active energy ray.

Further, by using a specific (meth) acrylate as the monomer (A1) component, the compatibility with the monomer (B1) component can be lowered to a predetermined range, and the louver structure can be formed more effectively.

Further, by using a polymer containing a specific (meth) acrylate as the component (A1), the refractive index of the plate-like region derived from the component (A1) in the louver structure can be improved, and the component derived from (B1) The difference in refractive index of the plate-like region is adjusted to a value equal to or greater than a given value.

Therefore, by including a specific (meth) acrylate polymer as the component (A1), it is possible to effectively obtain a cured product having a different refractive index along the film surface in combination with the characteristics of the component (B1) described later. A louver structure that alternately extends in direction.

In this way, it is possible to obtain a first structural region having a good incident angle dependency in light transmission and diffusion and a wide light diffusion incident angle region.

In addition, the "(meth) acrylate containing a plurality of aromatic rings" means a compound having a plurality of aromatic rings in the esterified portion of the (meth) acrylate.

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

Further, the (meth) acrylate containing a plurality of aromatic rings as the monomer (A1) component constituting the component (A1) may be, for example, biphenyl (meth)acrylate or naphthalene (meth)acrylate. Ester, decyl (meth) acrylate, benzyl phenyl (meth) acrylate, biphenyl oxyalkyl (meth) acrylate, naphthyloxyalkyl (meth) acrylate, (methyl) a decyloxyalkyl acrylate, a benzyl phenyl oxyalkyl (meth) acrylate or the like, or a substance substituted with a halogen, an alkyl group, an alkoxy group, a halogenated alkyl group or the like Wait.

Moreover, it is preferable that the (meth)acrylate containing a plurality of aromatic rings as the monomer (A1) component constituting the component (A1) is a compound containing a biphenyl ring, and it is particularly preferable to use the following formula (1). ) a biphenyl compound represented.

[Chemical Formula 2]

In the formula (1), R ¹ to R ¹⁰ are each independently, and at least one of R ¹ to R ¹⁰ is a substituent represented by the following formula (2), and the remainder is a hydrogen atom, a hydroxyl group, a carboxyl group, an alkyl group, or an alkane. Any one of an oxy group, a halogenated alkyl group, a hydroxyalkyl group, a carboxyalkyl group, and a halogen atom.

[Chemical Formula 3]

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

The reason for this is that a polymerization reaction rate of a monomer (Al) component can be made higher than that of a monomer (B1) component by using a biphenyl compound having a specific structure as a monomer (Al) component constituting the (Al) component. The speed is further accelerated.

Further, it can be presumed that the compatibility with the monomer (B1) component can be more easily reduced to a given range, and the refractive index of the plate-like region derived from the (Al) component in the louver structure can be improved, and In order to easily adjust the difference in refractive index from the plate-like region derived from the (Bl) component to a value equal to or higher than a given value.

Further, the monomer stage before curing by light is liquid, and even if a diluent solvent or the like is not used, it can be uniformly mixed with a urethane (meth) acrylate which is a representative example of the monomer (B1) component. .

Further, in the case where R ¹ to R ¹⁰ in the formula (1) include any one of an alkyl group, an alkoxy group, an alkyl halide group, a hydroxyalkyl group, and a carboxyalkyl group, it is preferred to use an alkyl moiety thereof. The carbon number is set to a value in the range of 1 to 4.

The reason is that if the carbon number is more than 4, the polymerization rate of the monomer (A1) component is lowered, or the refractive index of the plate-like region derived from the component (A1) in the louver structure is too low. There is thus a case where it is difficult to effectively form a given louver structure of the first structural region.

Therefore, in the case where R ¹ to R ¹⁰ in the formula (1) contain any one of an alkyl group, an alkoxy group, an alkyl halide group, a hydroxyalkyl group, and a carboxyalkyl group, it is preferred to use an alkyl moiety thereof. The carbon number is set to a value in the range of 1 to 3, and is preferably set to a value in the range of 1 to 2.

Further, R ¹ to R ¹⁰ in the formula (1) are preferably a halogenated alkyl group or a substituent other than a halogen atom, that is, a substituent which does not contain a halogen.

The reason for this is that it is preferable from the viewpoint of preventing the generation of dioxin and further protecting the environment when the light-diffusing film is incinerated.

In the conventional anisotropic light-diffusing film having a louver structure, when a given louver structure is obtained, the monomer component is generally used for the purpose of increasing the refractive index of the monomer component. Halogen substitution is carried out.

In this case, the biphenyl compound represented by the formula (1) can be set to have a high refractive index even when halogen substitution is not performed.

Therefore, by using the biphenyl compound represented by the general formula (1) as the monomer (A1) component, a good incident angle dependency can be exhibited even when halogen is not contained.

Further, it is preferred that any one of R ² to R ⁹ in the formula (1) is a substituent represented by the formula (2).

The reason for this is that, by setting the position of the substituent represented by the formula (2) to a position other than R ¹ and R ¹⁰ in the biphenyl ring, it is possible to effectively prevent the single stage before the photocuring is carried out. The orientation of the body (A1) is crystallized by orientation.

In this way, at the stage of photocuring, fine aggregation and phase separation of the monomer (A1) component and the monomer (B1) component can be achieved, and the first structure having a given louver structure can be obtained more effectively. Structure area.

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

In addition, it is generally preferable to set the number of repetitions m in the substituent represented by the formula (2) to an integer of 1 to 10.

The reason is that when the number of repetitions m is more than 10, the oxyalkylene chain linking the polymerization site and the biphenyl ring becomes too long, and the monomer (A1) component which hinders the polymerization site is formed. The case of aggregation between.

Therefore, it is preferable to set the number of repetitions m in the substituent represented by the formula (2) to an integer of 1 to 4, and particularly preferably to an integer of 1 to 2.

Further, from the same viewpoint, it is generally preferable to set the carbon number n in the substituent represented by the general formula (2) to an integer of 1 to 4.

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 it is preferable from the viewpoint of preventing a decrease in the polymerization rate of the monomer (A1) component. The number of carbon atoms n in the substituent represented by the formula (2) is an integer of 2 to 4, and is preferably an integer of 2 to 3.

In addition, as a specific example of the biphenyl compound represented by the formula (1), a compound which can be represented by the following general formulae (3) to (4) is preferable.

[Chemical Formula 4]

[Chemical Formula 5]

Further, the weight average molecular weight of the monomer (A1) component constituting the component (A1) is preferably set to a value in the range of 200 to 2,500.

For this reason, it is presumed that by setting the weight average molecular weight of the monomer (A1) component to a predetermined range, the polymerization rate of the monomer (A1) component can be further accelerated, and the singlet can be more effectively reduced. The copolymerizability of the component (A1) and the monomer (B1) component.

As a result, when the light is cured, the louver structure in which the (A1) component and the (B1) component are alternately extended along the film surface direction can be formed more effectively.

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 position of the polymerizable carbon-carbon double bond become too close due to the stereoscopic The polymerization rate is lowered by the hindrance, and the polymerization rate of the monomer (B1) component is approached, so that copolymerization with the monomer (B1) component tends to occur. On the other hand, when the weight average molecular weight of the monomer (A1) component is more than 2,500, the polymerization rate of the monomer (A1) component is lowered, and the polymerization rate of the monomer (B1) component is close to that of the monomer (B1) component. The copolymerization of the component (B1), as a result, may be difficult to form a louver structure efficiently.

Therefore, it is preferable to set the weight average molecular weight of the monomer (A1) component to a value in the range of 240 to 1,500, and it is particularly preferable to set the value in the range of 260 to 1,000. Further, the weight average molecular weight of the monomer (A1) component can be measured by colloidal permeation chromatography (GPC), or can be calculated from the structural formula based on the atomic weight of the atom. Further, it is preferable that the single body (A1) which forms a plate-like region having a high refractive index in the louver structure is provided in a single shape. The reason for this is that the plate-like region derived from the component (A1) in the louver structure, that is, the fluctuation of the refractive index of the plate-like region having a high refractive index can be effectively suppressed, thereby being more effectively obtained. A first structural area having a given louver structure.

In other words, when the compatibility between the monomer (A1) component and the monomer (B1) component is low, for example, when the monomer (A1) component is a halogen compound, it may be used as a monomer (A1). The third component in which the component is compatible with the monomer (B1) component, and another monomer (A1) component (for example, a non-halogen compound). However, in this case, the refractive index fluctuates and decreases in the plate-like region having a high refractive index derived from the component (A1) due to the influence of the third component. As a result, the difference in refractive index from the plate-like region having a low refractive index derived from the component (B1) may become uneven or may be excessively lowered. Therefore, it is preferable to select a monomer component having a refractive index which is highly compatible with the monomer (B1) component, and use it as a single monomer (A1) component.

In addition, for example, the biphenyl compound represented by the formula (3) to (4) which is a monomer (A1) component can be used as a single monomer because it has compatibility with the monomer (B1) component ( A1) Ingredients used. (6)-2 Low refractive index portion In addition, in the first structural region, the type of the material substance for forming the low refractive index portion of the plate-like region having a low refractive index among the plate-like regions having different refractive indices is not It is particularly limited, but it is preferably a polymer whose main component is a urethane (meth) acrylate. The reason for this is that, in the case of the material material, not only the louver structure as the first structural region but also the angle of incidence dependence of the first structural region and the opening angle of the diffused light can be further improved.

In other words, when the main component ((B1) component) of the low refractive index portion is a polymer of a urethane (meth) acrylate, not only the plate derived from the (A1) component can be more easily adjusted. The difference between the refractive index of the region and the refractive index of the plate-like region derived from the (B1) component, and the fluctuation of the refractive index of the plate-like region derived from the (B1) component can be effectively suppressed, so that the refractive index can be more effectively obtained. The first structural area of a given louver structure. Further, the term "(meth)acrylate" means both acrylate and methacrylate. First, a urethane (meth) acrylate which is a monomer (B1) component constituting the component (B1) is composed of (a) a compound containing at least two isocyanate groups, (b) a polyolefin diol, and (c) Formation of a hydroxyalkyl (meth) acrylate.

In addition, examples of the compound containing at least two isocyanate groups as the component (a) include 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, and 1,3-xylene diisocyanate, and 1,4. An alicyclic polyisocyanate such as an aromatic polyisocyanate such as xylene diisocyanate or an aliphatic polyisocyanate such as hexamethylene diisocyanate, isophorone diisocyanate (IPDI) or hydrogenated diphenylmethane diisocyanate, and the like. Biuret, isocyanuric acid, and adducts of reactants with compounds containing low molecular weight active hydrogen such as ethylene glycol, propylene glycol, neopentyl glycol, trimethylolpropane, castor oil (for example) Xylene diisocyanate-based trifunctional adduct) and the like. Further, among the above, it is particularly preferable to be an alicyclic polyisocyanate. The reason for this is that if the alicyclic polyisocyanate is used, it is easier to form a difference in the reaction rate of each isocyanate group than the aliphatic polyisocyanate due to the stereo-coordination and the like, thereby obtaining the obtained urethane. The molecular design of (meth) acrylate is easy. Further, it is particularly preferred that the component (a) is an alicyclic diisocyanate. The reason is that, in the case of an alicyclic diisocyanate, for example, it is possible to prevent the component (a) from reacting only with the component (b), or the component (a) reacting only with the component (c), and the component (a) is reliably prevented. The reaction with the component (b) and the component (c) prevents the occurrence of excess by-products. As a result, it is possible to effectively suppress the fluctuation of the refractive index in the plate-like region derived from the (B1) component in the first structural region, that is, in the plate-like region of low refractive index.

In the case of the alicyclic diisocyanate, the obtained monomer (B1) component and the biphenyl compound having a specific structure as a representative example of the monomer (A1) component can be obtained as compared with the aromatic diisocyanate. The compatibility is reduced to a given range, thereby forming the louver structure more efficiently. Further, when the alicyclic diisocyanate is used, the refractive index of the obtained monomer (B1) component can be made smaller than that of the aromatic diisocyanate, so that it can be increased as a representative example of the monomer (A1) component. The difference in refractive index of the biphenyl compound having a specific structure makes it possible to more effectively form a louver structure excellent in incident angle dependency. Further, among such alicyclic diisocyanates, isophorone diisocyanate (IPDI) is particularly preferable since the difference in reactivity between the two isocyanate groups is large.

Further, among the components of the urethane (meth) acrylate which is a component of the monomer (B1), examples of the polyolefin diol which is the component (b) include polyethylene glycol and polypropylene glycol. Polytetramethylene glycol, polyhexylene glycol, etc., among which polypropylene glycol is particularly preferred. The reason for this is that, in the case of polypropylene glycol, since the viscosity is low, it can be disposed without a solvent.

Further, in the case of polypropylene glycol, when the monomer (B1) component is cured, a favorable flexible segment of the cured product is formed, and the workability or mountability of the light-diffusing film can be effectively improved. Further, the weight average molecular weight of the monomer (B1) component can be mainly adjusted by the weight average molecular weight of the component (b). Here, the weight average molecular weight of the component (b) is generally from 2,300 to 19,500, more preferably from 4,300 to 14,300, and particularly preferably from 6,300 to 1,300. Further, among the components forming the urethane (meth) acrylate as the monomer (B1) component, examples of the hydroxyalkyl (meth) acrylate belonging to the component (c) include (methyl) ) 2-hydroxyethyl acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 3-hydroxy butyl (meth) acrylate Ester, 4-hydroxybutyl (meth)acrylate, and the like. Further, from the viewpoint of lowering the polymerization rate of the obtained urethane (meth) acrylate and more effectively forming a given louver structure, it is preferably a hydroxyalkyl methacrylate, particularly preferably A. 2-hydroxyethyl acrylate.

Further, the synthesis of the urethane (meth) acrylate from the components (a) to (c) can be carried out in accordance with a conventional method.

It is preferable to set the ratio of the components (a) to (c) at this time to (a) component in the molar ratio: (b) component: (c) component = 1 to 5: 1:1 to 5 ratio .

The reason for this is that the urethane (meth) acrylate can be efficiently synthesized by using the blending ratio, that is, the two hydroxyl groups of the component (b) have the component (a) One of the isocyanate groups is reacted and combined, and further, another isocyanate group which is contained in each of the two (a) components is reacted with the hydroxyl group of the component (c) to be bonded. Therefore, it is preferable to set the ratio of the components (a) to (c) to (a) component in the molar ratio: (b) component: (c) component = 1 to 3: 1:1 to 3 ratio It is especially suitable to set the ratio of 2:1:2. Further, the weight average molecular weight of the monomer (B1) component constituting the component (B1) is preferably set to a value in the range of 3,000 to 20,000. For this reason, it is presumed that the weight average molecular weight of the monomer (B1) component is set to a predetermined range, that is, the polymerization rate of the monomer (A1) component and the monomer (B1) component is generated. The difference is determined so that the copolymerization of the two components can be effectively reduced.

As a result, when the light is cured, the louver structure in which the (A1) component and the (B1) component are alternately extended can be effectively formed. 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 likely to occur. The copolymerization of the monomer (A1) component results in a situation in which it is difficult to form the louver structure efficiently. On the other hand, when the weight average molecular weight of the monomer (B1) component is a value exceeding 20,000, it may be difficult to form a louver structure in which the (A1) component and the (B1) component are alternately extended, or excessively lowered. When it is compatible with the monomer (A1) component, the monomer (A1) component is precipitated at the coating stage of the composition for a light-diffusion film. Therefore, it is preferable to set the weight average molecular weight of the monomer (B1) component to a value in the range of 5,000 to 15,000, and it is particularly preferable to set it to a value in the range of 7,000 to 13,000.

Further, the weight average molecular weight of the monomer (B1) component can be measured by colloidal permeation chromatography (GPC), or can be calculated from the structural formula based on the atomic weight of the constituent atoms. In addition, although the monomer (B1) component may be used in combination of two or more kinds having different molecular structures or weight average molecular weights, it is considered from the viewpoint of suppressing fluctuation in refractive index of the plate-like region derived from the (B1) component in the louver structure. It is advisable to use only one type. That is, in the case where a plurality of monomer (B1) components are used, the refractive index of the plate-like region derived from the (B1) component having a low refractive index fluctuates or becomes high, and thus may be derived from the (Al) component. The difference in refractive index of the plate-like region having a high refractive index becomes uneven or excessively lowered.

4. Second structural area

The light-diffusing film of the present invention is characterized in that, as a second structural region for isotropically diffusing incident light, a column having a plurality of pillars having a refractive index different from that of the medium is formed in the medium. Structure area. Hereinafter, the second structural region will be specifically described.

(1) Refractive index

Further, in the second structural region, the difference between the refractive index of the pillar and the refractive index of the medium is preferably set to 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, incident light can be stably reflected in the column structure region as the second structural region, and the incident angle dependency derived from the second structural region can be further improved. Sexual and diffuse light opening angle. That is, if the difference in refractive index is less than 0.01, the angle of the total reflection of the incident light in the column structure is extremely narrow, so that the angle of incidence is excessively lowered and the opening of the diffused light is opened. The situation where the angle is excessively narrowed.

Therefore, it is preferable to set the difference between the refractive index of the pillar of the second structural region and the refractive index of the medium to 0.05 or more, and particularly preferably 0.1 or more. Further, although the difference in refractive index is as large as possible, from the viewpoint of selecting a material which can form a columnar structure, about 0.3 is an upper limit.

(2) Maximum diameter Further, as shown in Fig. 9(a), in the second structural region, it is preferable to set the maximum diameter S3 of the cross section of the column to a value in the range of 0.1 to 15 μm. The reason for this is that by setting the maximum diameter to a value in the range of 0.1 to 15 μm, the incident light can be more stably reflected in the column structure region as the second structural region, and the second structural region can be further improved. The angle of incidence dependence and the angle of opening of the diffused light.

That is, if the maximum diameter is less than 0.1 μm, the light diffusibility may be difficult to display regardless of the incident angle of the incident light. On the other hand, when the maximum value is more than 15 μm, the light traveling straight in the column structure increases, and the uniformity of light diffusion may be deteriorated. Therefore, it is preferable to set the maximum diameter of the cross section of the pillar in the range of 0.5 to 10 μm in the second structural region, and it is particularly preferable to set the value in the range of 1 to 5 μm. Further, the cross-sectional shape of the pillar is not particularly limited, but it is preferably set to, for example, a circular shape, an elliptical shape, a polygonal shape, various shapes, or the like. Further, the cross section of the pillar refers to a section cut by a surface parallel to the surface of the membrane. Further, the maximum diameter, length, and the like of the column can be calculated by observation with an optical digital microscope.

(3) Length In addition, in the second structural region, it is preferable to set the length L3 of the column to a value in the range of 5 to 495 μm. The reason is that if the length is less than 5 μm, the length of the pillars is particularly insufficient, and the incident light traveling straight in the column structure increases, so that it is difficult to obtain sufficient incident angle dependency and diffused light. The case of the opening angle.

On the other hand, when the length is more than 495 μm, when the composition for a light-diffusion film is irradiated with an active energy ray to form a columnar structure, the column structure formed at the initial stage causes the direction of photopolymerization to diffuse. It is difficult to form the desired column structure.

Therefore, it is preferable that the length of the pillar is set to a value in the range of 40 to 310 μm in the second structural region, and it is particularly preferable to set the value in the range of 95 to 255 μm. Further, as shown in FIG. 9(c), the column structure may not form the upper and lower end portions in the film thickness direction in the second structure region. In this case, the width L4 of the lower end portion of the column structure is not determined by the thickness of the second structure region, but in general, it is preferably in the range of 0 to 50 μm, particularly preferably in the range of 0 to 5 μm. The value inside. (4) Distance between pillars In addition, as shown in Fig. 9(a), in the second structural region, it is preferable to set the distance between the pillars, that is, the gap P between adjacent pillars to 0.1. A value in the range of ~15 μm.

The reason for this is that by setting the distance to a value in the range of 0.1 to 15 μm, the incident light can be more stably reflected in the column structure region as the second structural region, and the second structural region can be further improved. Incident angle dependence and opening angle of diffused light. That is, if the distance is less than 0.1 μm, the light diffusibility may be difficult to display regardless of the incident angle of the incident light. On the other hand, when the distance is a value exceeding 15 μm, the straight light in the column structure increases, and the uniformity of light diffusion may be deteriorated. Therefore, it is preferable that the distance between the pillars is set to a value in the range of 0.5 to 10 μm in the second structural region, and it is particularly preferable to set the value in the range of 1 to 5 μm.

(5) Tilt angle

Further, as shown in FIGS. 9(b) to 9(c), in the second structural region, it is preferable that the pillars 22 are slanted at a constant inclination angle θb with respect to the film thickness direction. The reason is that, by setting the inclination angle of the pillar to be constant, the incident light can be more stably reflected in the pillar structure region as the second structural region, thereby further increasing the incident angle from the second structural region. Dependence and the angle of opening of the diffused light.

Further, as shown in Fig. 9(d), it is preferable that the column structure is curved. The reason is because the column structure is curved, that is, the incident light traveling straight in the column structure can be reduced, and the uniformity of light diffusion can be improved. Further, such a bent column structure can be obtained by irradiating light while changing the irradiation angle of the irradiation light when the second active energy ray irradiation described in the second embodiment is performed, but it is also considerably dependent on the formation of the column. The type of material of the structure. In addition, θb is an angle of 0 which is measured with respect to the normal line of the film surface measured in a cross section perpendicular to the film surface and cut into two face cutting films along the axis of the entire column. The inclination angle (°) of the column at °° (the angle between the normal and the narrow side of the angle formed by the column). Further, as shown in FIG. 9(b), the inclination angle when the column is inclined to the left side is used as a reference, and the inclination angle when the column is inclined to the left side is represented by a negative value. (6) Thickness Further, it is preferable to set the thickness of the second structural region to a value in the range of 5 to 495 μm.

The reason for this is that by setting the thickness of the second structural region to a value within the range, it is possible to stably ensure the length of the pillar along the film thickness direction, and in the column structure region as the second structural region. In order to stably reflect the incident light, the angle of incidence dependence from the second structural region and the opening angle of the diffused light are further increased.

That is, if the thickness is less than 5 μm, the length of the pillar is insufficient, and the incident light traveling straight in the column structure increases, so that it is difficult to obtain sufficient incident angle dependency and diffused light. The case of the opening angle. On the other hand, when the thickness is more than 495 μm, when the composition for a light-diffusing film is irradiated with an active energy ray to form a columnar structure, the column structure formed at the initial stage causes the direction of photopolymerization to diffuse. There are cases where it is difficult to form a desired column structure. Therefore, it is preferable to set the thickness of the second structural region to a value in the range of 40 to 310 μm, and it is particularly preferable to set the value in the range of 95 to 255 μm.

(7) Material substances

(7)-1 column

Further, in the second structural region, the type of the material constituting the pillar is not particularly limited, but a polymer having a main component as a (meth) acrylate containing a plurality of aromatic rings is preferable. The reason for this is that, in the case of the material material, not only the column structure as the second structure region but also the angle of incidence dependence of the second structure region and the opening angle of the diffused light can be further improved. In other words, it can be estimated that when the main component of the pillar (hereinafter sometimes referred to as (A2) component) is a specific (meth) acrylate polymer, when the second structural region is formed, it can be made The polymerization rate of the monomer component (hereinafter sometimes referred to as the monomer (A2) component) which is a component (A2) due to polymerization is a main component of a medium to be described later due to polymerization (hereinafter sometimes referred to as a (B2) component. The monomer component (hereinafter sometimes referred to as the monomer (B2) component) has a high polymerization rate, and a given difference in the polymerization rate between the monomer components is obtained, thereby effectively reducing the copolymerizability of the two monomer components. . As a result, it is possible to efficiently form a columnar structure in which a column containing the component (A2) is formed in a medium containing the component (B2) by irradiation with an active energy ray.

Further, by using a specific (meth) acrylate as the monomer (A2) component, the compatibility with the monomer (B2) component can be lowered to a predetermined range, and the column structure can be formed more efficiently. Further, by using a specific (meth) acrylate as a monomer (A2) component, the refractive index of the pillar derived from the (A2) component in the column structure can be improved, and the component derived from the (B2) component The difference in refractive index of the medium is adjusted to a value above a given value. Therefore, by including a specific (meth) acrylate polymer as the component (A2), it can be effectively combined with the characteristics of the component (B2) described later to effectively obtain a medium containing the component (B2). Column structure of the column of the component (A2). In this way, it is possible to obtain a second structural region having a good incident angle dependency in light transmission and diffusion and a wide light diffusion incident angle region.

Further, the details of the (meth) acrylate containing a plurality of aromatic rings as the monomer (A2) component constituting the component (A2) are repeated with the content of the monomer (A1) component of the first structural region. Therefore omitted.

(7)-2 vehicle

Further, in the second structural region, the kind of the material material constituting the vehicle is not particularly limited, but a polymer whose main component is a urethane (meth) acrylate is preferable. The reason for this is that, in the case of the material material, not only the column structure as the second structure region but also the angle of incidence dependence of the second structure region and the opening angle of the diffused light can be further improved. In other words, by setting the main component ((B2) component) of the vehicle to a polymer of a urethane (meth) acrylate, it is possible to more easily adjust the column derived from the component (A2). The difference between the refractive index and the refractive index of the medium derived from the (B2) component, and the fluctuation of the refractive index of the medium derived from the (B2) component can be effectively suppressed, so that a given column can be obtained more efficiently The second structural area of the structure. Further, the details of the urethane (meth) acrylate which is the monomer (B2) component constituting the component (B2) are omitted since the content of the monomer (B1) component in the first structural region is repeated. .

5. Total film thickness

Further, it is preferable to set the total film thickness of the light-diffusing film of the present invention to a value in the range of 50 to 500 μm. The reason for this is that if the total film thickness of the light-diffusing film is less than 50 μm, the light traveling straight in the column structure and the louver structure increases, and it may be difficult to exhibit light diffusibility. On the other hand, when the total film thickness of the light-diffusion film is more than 500 μm, when the composition for the light-diffusing film is irradiated with the active energy ray to form the column structure and the louver structure, the column structure and the louver structure formed at the initial stage are formed. The direction in which the photopolymerization proceeds is diffused, so that it is difficult to form the desired column structure and louver structure.

Therefore, it is preferable to set the total film thickness of the light-diffusing film to a value in the range of 80 to 350 μm, and it is particularly preferable to set the value in the range of 100 to 260 μm. Moreover, the light diffusing film of the present invention may have a configuration in which the first and second structural regions are formed in a single film, or may be formed by laminating a film having only the first structural region and a film having only the second structural region. The composition of the formation. In particular, since it is possible to fundamentally suppress the occurrence of bubble mixing or the like between the first and second structural regions, it is preferable to form the two structures in a single film. In addition, the first structural region and the second structural region may be sequentially disposed in the vertical direction along the film thickness direction of the light diffusion film, and the order and number thereof are not particularly limited.

6. Combination of tilt angles

Further, in the case of the light-diffusing film of the present invention, it is possible to adjust the inclination angle θa of the plate-like region in the first structural region with respect to the film thickness direction and the film thickness direction in the second mechanism region, respectively. The column is inclined at an angle θb to change its light diffusion characteristics. For example, by repeating the incident angle dependency of each structural region, not only the fluctuation of the diffusion characteristics can be suppressed, but also a good incident angle dependency can be obtained, and the opening angle of the diffused light can be effectively widened.

In this case, it is preferable that the inclination angle θa of the plate-like region with respect to the film thickness direction is set to a value within a range of -80 to 80° in the first structural region, and in the second mechanism region, the relative The inclination angle θb of the pillar in the film thickness direction is set to a value in the range of -80 to 80°, and the absolute value of θa-θb is set to a value in the range of 0 to 80°, preferably θa The absolute value of -θb is set to a value in the range of 5 to 20°.

Further, the contents of θa and θb herein are as described above. In addition, by staggering the incident angle dependency of each structural region, it is possible to effectively and easily widen the light diffusion incident angle region. In this case, it is preferable that the inclination angle θa of the plate-like region with respect to the film thickness direction is set to a value within a range of -80 to 80° in the first structural region, and in the second mechanism region, the relative The inclination angle θb of the pillar in the film thickness direction is set to a value in the range of -80 to 80°, and the absolute value of θa-θb is set to a value within a range of 5 to 60°, preferably θa The absolute value of -θb is set to a value in the range of 20 to 45°.

7. Use

Further, as shown in FIG. 10, it is preferable to use the light diffusion film of the present invention in the reflective liquid crystal display device 100. The reason for this is that, in the case of the light-diffusing film of the present invention, the external light can be condensed and efficiently transmitted to the inside of the liquid crystal display device, and the light can be effectively diffused as a light source. .

Therefore, the light-diffusing film of the present invention is preferably disposed above or below the liquid crystal cell 110 including the glass plate (104, 108), the liquid crystal 106, the specular reflection plate 107, and the like, and is used as the light diffusion plate 103 of the reflective liquid crystal display device 100.

Further, a wide field of view polarizing plate or a wide field of view phase difference plate can also be obtained by using the light diffusing film of the present invention in the polarizing plate 101 or the phase difference plate 102.

[Second Embodiment]

A second embodiment of the present invention is a method of producing a light-diffusing film, which has a first structural region for anisotropically diffusing incident light and a second structural region for isotropically diffusing incident light. A method of producing a light diffusion film comprising the following steps (a) to (d).

(a) a step of preparing a composition for a light diffusion film;

(b) a step of applying a composition for a light-diffusing film onto an engineering sheet to form a coating layer;

(c) irradiating the coating layer with the first active energy ray, 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, which are alternately arranged in parallel along the film surface direction. a louver structure region, and a portion of the upper portion of the coating layer that does not form a louver structure region;

(d) further applying a second active energy ray to the coating layer, and forming a column having a plurality of pillars having a refractive index different from the medium in the medium as the second structural region in the region where the louver structure is not formed The step of the structural region.

Hereinafter, a method of manufacturing a light diffusion film according to a second embodiment of the present invention will be specifically described with reference to the drawings, focusing on differences from the first embodiment.

1. Step (a): Preparation Step of Composition for Light-Diffusing Film Step (a) is a step of preparing a composition for a light-diffusing film.

More specifically, it is preferred to stir the monomer (A) component and the monomer (B) component at a high temperature of 40 to 80 ° C to prepare a uniform mixed solution.

In addition, at the same time, it is preferable to add a diluent solvent to the mixed liquid as needed, and then add a diluent solvent as needed to achieve a desired viscosity while stirring to a uniform level. A solution of the composition for a light diffusing film was obtained.

Further, the monomer (A) component is a monomer component of the component (A) constituting the high refractive index portion of the first and second structural regions due to polymerization, and the monomer (B) component is first formed by polymerization. And a monomer component of the component (B) of the low refractive index portion of the second structural region.

In addition, as for the details of the types of the monomer (A) component and the monomer (B) component, respectively, as the monomers (A1) and (A2), (B1), and (B2) components in the first embodiment, respectively. The description is described and therefore omitted.

(1) Refractive index of monomer (A) component

Further, it is preferred to set the refractive index of the monomer (A) component to a value in the range of 1.5 to 1.65.

The reason for this is that by setting the refractive index of the monomer (A) component to a value within the range, it is possible to more easily adjust the portion derived from the component (A) in the louver structure and the column structure, and the source thereof. The difference in refractive index of the component (B) makes it possible to more efficiently obtain a light-diffusing film having a given louver structure and column structure.

That is, if the refractive index of the monomer (A) component is less than 1.5, the difference in refractive index from the monomer (B) component is too small, and it may be difficult to obtain a desired incident angle dependency. Sexual situation. On the other hand, when the refractive index of the monomer (A) component exceeds 1.65, the difference in refractive index from the monomer (B) component becomes large, but the viscosity is excessively lowered, and it is difficult to form a monomer. (B) The case where the components are compatible.

Therefore, it is preferable to set the refractive index of the monomer (A) component to a value in the range of 1.55 to 1.6, and it is particularly preferable to set the value in the range of 1.56 to 1.59.

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

Further, the refractive index of the monomer (A) component can be measured in accordance with, for example, JIS K0062.

(2) Content of monomer (A) component

In addition, the content of the monomer (A) component is preferably in the range of 25 to 400 parts by weight based on 100 parts by weight of the monomer (B) component to be described later.

The reason for this is that by setting the content of the monomer (A) component to a value within the range, it is possible to effectively reduce the miscibility with the monomer (B) component while effectively reducing the light irradiation. The copolymerization of the components enables efficient formation of a given louver structure and column structure.

In other words, when the content of the monomer (A) component is less than 25 parts by weight, the ratio of the component (A) to the monomer (B) component is small, and the source of the louver structure and the column structure is The width or the like of the portion of the component (A) is too small as compared with the width of the portion derived from the component (B), and the like, and it may be difficult to obtain a louver structure and a column structure having a good incident angle dependency. Further, the length of the louver or the pillar in the thickness direction of the light diffusion film may be insufficient. On the other hand, when the content of the monomer (A) component is more than 400 parts by weight, the ratio of the monomer (A) component to the monomer (B) component increases, and the louver structure and the column structure are The width or the like of the portion derived from the component (A) is excessively larger than the width of the portion derived from the component (B), and conversely, it may be difficult to obtain a louver structure and a column structure having a good incident angle dependency. . Further, the length of the louver or the pillar in the thickness direction of the light diffusion film may be insufficient.

Therefore, it is preferable to set the content of the monomer (A) component to a value in the range of 40 to 300 parts by weight, preferably 50 to 200 parts by weight, per 100 parts by weight of the monomer (B) component. The value in the range.

(3) Refractive index of monomer (B) component

Further, it is preferred to set the refractive index of the monomer (B) component to a value in the range of 1.4 to 1.5.

The reason is that it is easier to adjust the fraction derived from the component (A) and the component derived from (B) in the louver structure and the column structure by setting the refractive index of the monomer (B) component to a value within the range. The difference in refractive index of the portion allows a light diffusing film having a given louver structure and column structure to be more efficiently obtained.

In other words, when the refractive index of the monomer (B) component is less than 1.4, the difference in refractive index from the monomer (A) component is large, but compatibility with the monomer (A) component. Extremely deteriorated, so that it is difficult to form a louver structure and a column structure. On the other hand, when the refractive index of the monomer (B) component exceeds 1.5, the difference in refractive index from the monomer (A) component becomes too small, and it is difficult to obtain a desired incident angle dependency. The situation.

Therefore, it is preferable to set the refractive index of the monomer (B) component to a value in the range of 1.45 to 1.49, and it is particularly preferable to set the value in the range of 1.46 to 1.48.

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

Further, the refractive index of the monomer (B) component can also be measured in accordance with, for example, JIS K0062.

(4) Content of monomer (B) component

Further, the content of the monomer (B) component is preferably in the range of 20 to 80% by weight based on the total amount (100% by weight) of the composition for a light-diffusing film.

The reason is that when the content of the monomer (B) component is less than 20% by weight, the ratio of the monomer (B) component to the monomer (A) component is small, and the louver structure and the column structure are used. The width or the like of the portion derived from the component (B) is too small as compared with the width of the portion derived from the component (A), and it is difficult to obtain a louver structure and a column structure having a good incident angle dependency. Happening. Further, the length of the louver or the pillar in the thickness direction of the light diffusion film may be insufficient.

On the other hand, when the content of the monomer (B) component is more than 80% by weight, the ratio of the monomer (B) component to the monomer (A) component increases, and the louver structure and the column structure are The width or the like of the portion derived from the component (B) is excessively larger than the width of the portion derived from the component (A), and conversely, it is difficult to obtain a louver structure and a column structure having a good incident angle dependency. Happening. Further, the length of the louver or the pillar in the thickness direction of the light diffusion film may be insufficient.

Therefore, it is preferable to set the content of the monomer (B) component to a value in the range of 30 to 70% by weight, preferably 40 to 60% by weight, based on the total amount of the composition for a light-diffusing film. The value in the range.

(5) Photopolymerization initiator

Further, in the composition for a light-diffusing film of the present invention, it is preferred to contain a photopolymerization initiator as the component (C) as required.

The reason for this is that when a composition for a light-diffusing film is irradiated with an active energy ray by containing a photopolymerization initiator, a given louver structure and column structure can be efficiently formed.

Here, the photopolymerization initiator refers to a compound which generates radical seeds by irradiation with an active energy ray such as ultraviolet rays.

As the photopolymerization initiator, for example, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin n-butyl ether, benzoin isobutyl ether, acetophenone, dimethylaminoacetophenone, 2, 2 may be used. -dimethoxy-2-phenylacetophenone, 2,2-diethoxy-2-phenylacetophenone, 2-hydroxy-2-methyl-1-phenyl-1-propanone, 1 -hydroxycyclohexyl phenyl ketone, 2-methyl-1-(4-methylthiophenyl)-2-morpholinyl-1-propanone, 4-(2-hydroxyethoxy)phenyl-2- (hydroxy-2-propyl) ketone, benzophenone, p-phenylbenzophenone, 4,4-diethylaminobenzophenone, dichlorobenzophenone, 2-methylindole, 2-ethyl hydrazine, 2-tert-butyl fluorene, 2-amino hydrazine, 2-methyl 9-oxo sulphur [mouth + mountain] [mouth + star] (thioxanthone), 2-ethyl 9-oxygen Sulfur [mouth + mountain] [mouth + star], 2-chloro 9-oxo sulfur [mouth + mountain] [mouth + star], 2,4-dimethyl 9-oxo sulfur [mouth + mountain] [mouth + star ], 2,4-diethyl 9-oxosulfur [mouth + mountain] [mouth + star], benzoin dimethyl ketal, acetophenone dimethyl ketal, p-dimethylamino benzoate Oligomeric [2-hydroxy-2-methyl-1-[4-(1-methylvinyl)phenyl]propane, etc., which can be used alone One kind may also be used in combination of two or more.

In addition, the content of the photopolymerization initiator is preferably in the range of 0.2 to 20% by weight based on 100% by weight of the total of the monomer (A) component and the monomer (B) component. The value is preferably in the range of 0.5 to 15% by weight, and particularly preferably in the range of 1 to 10% by weight.

(6) Other additives

Further, other additives may be appropriately added within a range not impairing the effects of the present invention.

As other additives, for example, an antioxidant, an ultraviolet absorber, an antistatic agent, a polymerization accelerator, a polymerization inhibitor, an infrared absorber, a plasticizer, a diluent solvent, and a leveling agent can be given.

In addition, the content of the other additives is generally set to a value in the range of 0.01 to 5% by weight based on 100% by weight of the total of the monomer (A) component and the monomer (B) component. The value in the range of 0.02 to 3% by weight is more preferably in the range of 0.05 to 2% by weight.

2. Step (b): the smear step

As shown in FIG. 11(a), the step (b) is a step of applying the prepared composition for a light-diffusing film to the engineered sheet 2 to form the coating layer 1.

As for the engineering film, it can be used regardless of the plastic film or paper.

In the case of the plastic film, a polyester film such as a polyethylene terephthalate film, a polyolefin film such as a polyethylene film or a polypropylene film, or a cellulose film such as a triethylene cellulose film, and Polyimine film or the like.

Further, as for the paper, for example, it may be cellophane, coated paper, laminated cardboard, or the like.

Further, in the engineering sheet, in order to facilitate the peeling of the obtained light-diffusing film from the engineering sheet after curing by light, it is preferable to provide a release layer on the coated surface side of the composition for a light-diffusing film of the engineering sheet.

The release layer can be formed using a conventionally used release agent such as a ruthenium-based release agent, a fluorine-based release agent, an alkyd-based release agent, or an olefin-based release agent.

Further, the thickness of the engineering sheet is generally set to a value in the range of 25 to 200 μm.

Further, as a method of applying the composition for a light-diffusing film to an engineering sheet, for example, a blade coating method, a roll coating method, a bar coating method, a knife coating method, an optical coating method, and a gravure coating method can be used. The conventional method is carried out.

Further, in this case, it is preferable to set the thickness of the coating layer to a value in the range of 100 to 700 μm.

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

The step (c) is a step of performing a first active energy ray irradiation on the coating layer, and forming a plurality of plate-like regions having different refractive indices as the first structural region along the film in a lower portion of the coating layer. The louver structure region is alternately arranged in parallel in the plane direction, and a region where the louver structure is not formed remains in the upper portion of the coating layer.

That is, as shown in FIG. 11(b), the coating layer 1 formed on the engineered sheet 2 is irradiated with the active energy ray 50 composed only of the direct light whose irradiation angle has been controlled.

More specifically, for example, as shown in FIG. 12(a), the ultraviolet irradiation device 120 of the cold mirror 122 for collecting light is provided in the linear ultraviolet lamp 125 (for example, if it is a commercially available product, there are Eyegraphics). In the ECS-4011GX or the like, the infrared cut filter 121 and the light blocking plate 123 are disposed, and the active energy ray 50 composed only of the direct light having the controlled irradiation angle is taken out and applied to the formed sheet 2 Layer 1 is illuminated.

Further, the linear ultraviolet lamp is generally set to a value in the range of -80 to 80° based on the direction orthogonal to the longitudinal direction of the engineered sheet 2 having the coating layer 1 (0°). It is preferably set to a value in the range of -50 to 50°, and particularly preferably set to a value in the range of -30 to 30°.

Here, the reason why the linear light source is used is that it is possible to efficiently and stably manufacture the plate-like regions having different refractive indexes alternately and arranged in parallel with respect to the film thickness direction at a constant inclination angle as the first structure. The area of the louver structure of the area.

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

At this time, as for the irradiation angle of the irradiation light, as shown in FIG. 12(b), it is generally preferable to set the irradiation angle θ3 at an angle of 0 to the normal to the surface of the coating layer 1 to be - A value in the range of 80 to 80°.

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

Further, the irradiation angle θ3 is preferably a width (irradiation angle width) θ3' of 1 to 80°.

The reason is that if the irradiation angle width θ3' is less than 1°, the interval between the louver structures is too narrow, and it may be difficult to obtain the desired first structural region. On the other hand, when the irradiation angle width θ3' exceeds a value of 80°, the irradiation light is excessively dispersed, and the louver structure may be difficult to form.

Therefore, it is preferable to set the irradiation angle width θ3' of the irradiation angle θ3 to a value in the range of 2 to 45°, and it is particularly preferable to set the value in the range of 5 to 20°.

Further, as the irradiation light, ultraviolet rays, electron beams, or the like may be mentioned, but it is preferred to use ultraviolet rays.

The reason is that 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 during the polymerization, and it is difficult to form a louver structure. Happening. On the other hand, when compared with visible light or the like, the ultraviolet curable resin which is cured by irradiation with ultraviolet rays and the photoinitiator which can be used are rich in changes, so that the monomer (A) component and the monomer (B) component can be broadened. The range of choices.

Further, as for the irradiation condition of the ultraviolet rays, it is preferable to set the illuminance to a value in the range of 0.01 to 50 mW/cm ² .

The reason is that when the illuminance is less than 0.01 mW/cm ² , it is possible to sufficiently form a region in which the louver structure is not formed, but it may be difficult to form the louver structure clearly. On the other hand, when the illuminance is a value exceeding 50 mW/cm ² , the phase separation of the component (A) and the component (B) is solidified, and conversely, it may be difficult to form the louver structure clearly.

Therefore, it is preferable to set the illuminance of the ultraviolet ray to a value in the range of 0.05 to 20 mW/cm ² , and it is particularly preferable to set the value in the range of 0.1 to 10 mW/cm ² .

Further, it is preferable that the coating layer formed on the engineering sheet is moved at a speed of 0.1 to 10 m/min and passed through the ultraviolet ray irradiation portion of the ultraviolet ray irradiation device.

The reason is that if the speed is less than 0.1 m/min, there is a case where the mass productivity is excessively lowered. On the other hand, if the speed is more than 10 m/min, the curing angle of the coating layer will change faster than the formation of the louver structure, in other words, faster than the formation of the louver structure. There is a case where the construction of the louver structure is insufficient.

Therefore, it is preferable to move the coating layer formed on the engineering sheet at a speed in the range of 0.2 to 5 m/min, and pass through the ultraviolet irradiation portion of the ultraviolet irradiation device, particularly preferably in the range of 0.5 to 3 m/min. Speed through.

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

The step (d) is a step of performing a second active energy ray irradiation on the coating layer, and forming a refractive index and a medium in the medium as the second structural region in the region where the louver structure is not formed. A column structure area formed by a plurality of different pillars.

That is, the coating layer formed on the engineering sheet is irradiated with parallel light having a high degree of parallelism of light. When the parallel light is irradiated, the coating layer may be directly irradiated. However, it is preferable to laminate the release film on the surface of the exposed coating layer and irradiate it over the release film. As for the release film, a material having ultraviolet ray permeability among the materials described in the above engineering sheet can be appropriately selected.

Here, the direct light of the linear light source used in the first active energy ray irradiation step does not have a broadening in a direction perpendicular to the axial direction of the linear light source, and is substantially parallel, but in a line with the linear light source There is no uniformity in the direction of the direction of the light in the direction parallel to the axis, which is random.

On the other hand, the so-called parallel light in the second active energy ray irradiation means that the direction of the emitted light does not have substantially parallel light when viewed 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 as shown in FIG. 13(b) to (c). In the case where the light from the linear light source 206 is converted into parallel light by the assembly 210 of the tubular member 208, the coating layer is irradiated.

Therefore, as a specific example of the parallel light irradiation device shown in Fig. 13 (a), for example, a device for mounting a uniform exposure attachment of an accessory in an ultraviolet light source "HYPERCURE 200", which is manufactured by Yamashita Electric Co., Ltd., can be used. .

Further, it is preferable to set the parallelism of the parallel light to a value of 10 or less.

The reason for this is that by setting the parallelism to a value of 10° or less, it is possible to efficiently and stably manufacture a plurality of pillars which are formed at a certain inclination angle with respect to the film thickness direction as the second structure. The column structure area of the area.

That is, if the parallelism is a value exceeding 10°, there is a case where the column structure cannot be formed.

Therefore, it is preferable to set the parallelism of the parallel light to a value of 5 or less, and it is preferable to set it to a value of 2 or less.

Further, as the irradiation light, ultraviolet rays, electron beams, and the like are exemplified, but it is preferable to use ultraviolet rays for the same reason as in the first active energy ray irradiation step.

Further, as for the irradiation condition of the ultraviolet rays, it is preferable to set the illuminance to a value in the range of 0.01 to 30 mW/cm ² .

The reason is that when the illuminance is less than 0.01 mW/cm ² , it may be difficult to form the column structure clearly. On the other hand, when the illuminance is a value exceeding 30 mW/cm ² , the phase separation of the component (A) and the component (B) is performed immediately before the phase separation is performed, and conversely, it may be difficult to form the column structure clearly.

Therefore, it is preferable to set the illuminance of the ultraviolet ray to a value in the range of 0.05 to 20 mW/cm ² , and it is particularly preferable to set the value in the range of 0.1 to 10 mW/cm ² .

Further, the moving speed of the coating layer or the irradiation angle of the irradiation light may be the same as the first active energy ray irradiation step.

Further, it is preferable to irradiate the active energy ray in addition to the first and second active energy ray irradiation so as to achieve the integrated light amount for sufficiently curing the coating layer.

In this case, the active energy ray is intended to sufficiently cure the coating layer. Therefore, it is preferable to use light that is not parallel light or the like in the traveling direction.

Further, the light-diffusing film after the photo-curing step is finally put into a usable state by peeling off the engineered sheet.

[Examples]

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

[Example 1]

1. Synthesis of monomer (B) component

In the container, the polypropylene glycol (PPG) 1 mol of the weight average molecular weight of 9200 as the component (b) is contained, and the isophorone diisocyanate (IPDI) 2 mol as the component (a) is contained, and as (c) After the component of 2-hydroxyethyl methacrylate (HEMA) 2 moles, it was polymerized according to a conventional method to obtain a polyether urethane methacrylate having a weight average molecular weight of 9,900.

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

‧GPC measuring device: HTC-8020 by Tosoh (stock)

‧GPC column: Tosoh (share) system (the following is recorded in order)

TSK guard column HXL-H

TSK gel GMHXL (×2)

TSK gel G2000HXL

‧ Determination of solvent: tetrahydrofuran

‧Measurement temperature: 40 ° C

2. Preparation of composition for light diffusion film

Then, 100 parts by weight of the polyether urethane methacrylate having a weight average molecular weight of 9900 as the monomer (B) component obtained is added, and the weight represented by the following formula (3) as the component (A) is added. 100 parts by weight of o-phenylphenoxyethoxyethyl acrylate (NK Ester A-LEN-10, manufactured by Shin-Nakamura Chemical Co., Ltd.) having an average molecular weight of 268, and 2-hydroxy-2 as (C) component After 10 parts by weight of methyl phenylacetone, the mixture was heated and mixed at 80 ° C to obtain a composition for a light-diffusing film. Further, the refractive index of the monomer (A) component and the monomer (B) component is measured by an Abbe refractometer (trade name "Abe refractometer DR-M2" manufactured by Aiwa ATAGO Co., Ltd., Na light source, wavelength: 589 nm). The results were measured in accordance with JIS K0062, and the results were 1.58 and 1.46, respectively.

[Chemical Formula 6]

3. Coating of composition for light diffusion film

Then, the obtained composition for anisotropic light-diffusing film was applied onto a transparent polyethylene terephthalate film (hereinafter referred to as PET) as a film of a work piece using a dispenser to obtain a film thickness. 200 μm coating layer.

4. Light curing of the coating layer

(1) First ultraviolet irradiation

Then, an ultraviolet irradiation device (ECS-4011GX manufactured by Eyegraphics Co., Ltd.) equipped with a cold mirror for collecting light is provided in a linear high-pressure mercury lamp as shown in Fig. 12(a).

Then, a light shielding plate is provided on the infrared cut filter frame, and the ultraviolet ray irradiated onto the surface of the coating layer is set to a laminate including the coating layer and PET when viewed from the longitudinal direction of the linear ultraviolet lamp. When the normal direction is set to 0°, the direct ultraviolet irradiation angle (θ3 in Fig. 12(b)) from the lamp is -40°.

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

In addition, the reflected light at the visor or the like becomes stray light inside the illuminator, and in order to prevent the photocuring of the coating layer from being affected, a light shielding plate is also provided in the vicinity of the conveyor belt, and only the ultraviolet ray directly emitted from the lamp is applied. Set the layer illumination mode.

Then, the coating layer was irradiated with ultraviolet rays while moving at a speed of 0.2 m/min in the right direction of Fig. 12 (a) by a conveyor belt.

(2) Second ultraviolet irradiation

Then, after passing through the first ultraviolet irradiation step by the linear light source, the exposed surface side of the coating layer was laminated with a release film having a thickness of 38 μm (SP-PET382050 manufactured by Lintech Co., Ltd.).

Then, a device in which the parallelism is set to 2° or less by using a uniform exposure attachment in which an accessory is mounted in an ultraviolet point light source (HYPERCURE 200 manufactured by Yamashita Electric Co., Ltd.) is adopted, so that the incident angle of the parallel light reaches 40°. The film was irradiated over the release film to obtain a light diffusion film having a total film thickness of 200 μm.

The average illuminance at this time was set to 5 mW/cm ² and the lamp height was set to 800 mm.

In addition, the thickness of the light-diffusion film was measured using a constant-pressure thickness measuring device (TECLOCK PG-02J by Takara Seisakusho Co., Ltd.).

Further, as shown in Fig. 14 (a), the obtained light-diffusing film was confirmed to have a light-diffusing film having a slant angle of -27° and a columnar inclination angle of 27°.

Further, Fig. 14(a) is a schematic view showing a cross section of the film when it is cut by a face perpendicular to the plate-like region of the louver structure.

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

Further, a cross-sectional photograph of the obtained light-diffusing film is shown in Figs. 15(a) to (b). Fig. 15 (a) is a cross-sectional photograph of a film cut with a face perpendicular to the plate-like region of the louver structure, and Fig. 15 (b) is a cross-sectional photograph of the film cut with a face perpendicular to the cut surface of Fig. 15 (a).

5. Determination

Using a variable angle colorimeter (VC-2 manufactured by Suga Suga Tester Co., Ltd.), as shown in Fig. 14 (a), from the upper side of the obtained light diffusion film, the film was incident at an incident angle of θ1 = 60°. Into the light (C light source, field of view 2 °).

Then, the spread of the diffused light diffused by the light diffusing film and the distribution of the luminance (%) thereof were measured. The measurement result is shown on the horizontal axis of which the value of the vertical axis of the scatter diagram shown in Fig. 14 (c) is 0°.

That is, the value of the horizontal axis represents the range of the spread angle (°) of the diffused light, and the color of the drawn dot indicates the luminance (%) of the diffused light diffused at the angle.

Here, the relationship between the color of the painted dots and the brightness (%) is that the closer the color of the painted dots is to red, the closer the brightness is to 100%, and the closer the color of the painted dots is to green, the closer the brightness is to 50%. The closer the color is to navy, the closer the brightness is to 0%. Moreover, the details are shown in Fig. 14 (b).

Further, in order to measure the spread of the diffused light in the width direction of the incident light and the distribution of the luminance (%), the light diffusing film is placed in the same plane with a given point on the surface of the light diffusing film as a center. The same measurement was carried out while rotating in the range of -80 to 80°. Further, the angle of the rotation refers to an angle of rotation when the angle of the light diffusion film at the time of measurement described above is 0°. For example, the measurement result when the light diffusion film is rotated by 20° is shown on the horizontal axis of which the value of the vertical axis of the scatter diagram shown in Fig. 14(c) is 20°.

Therefore, in the case of the scattergram shown in FIG. 14(c), for example, a region where the diffused light distribution having a luminance of 30% or more is a region surrounded by a broken line in FIG. 14(c).

Then, as shown in FIGS. 14(d) to (k), the incident angle θ1 with respect to the light diffusion film is changed to 50°, 40°, 30°, 0°, -30°, -40°, -50, respectively. ° and -60°, the distribution of the spread of the diffused light and the luminance (%) thereof were measured in the same manner as in the case of the incident angle θ1 = 60°.

6. Results

As shown in FIGS. 14(c) to 14(k), in the light-diffusing film of the first embodiment, although the incident angle θ1 of the incident light is in the range of about 0°, it is difficult to cause light diffusion, but at the incident angle θ1= In the range of 30 to 60°, isotropic light diffusion caused by the column structure region is generated, and anisotropic light diffusion caused by the louver structure region is generated in the range of the incident angle θ1=-60 to -30°. It can be seen that the light diffusion incident angle region can be effectively enlarged by shifting the light diffusion incident angle dependency caused by the two structural regions.

[Embodiment 2]

In the second embodiment, except that the θ3 of the first ultraviolet ray irradiation was changed to 40° when the coating layer was cured, the same operation as in the first embodiment was carried out, and the slanting angle of the louver structure was 27°, and the column was A light diffusion film as shown in Fig. 16 having a tilt angle of 27°.

In addition, the distribution of the spread of the diffused light and the luminance (%) thereof was carried out in the same manner as in the first embodiment except that the incident angle θ1 with respect to the light-diffusing film was 25°, 35°, 45°, and 55°, respectively. Determination.

As a result, in the light diffusion film of the second embodiment, since the light diffusion incident angle dependency in the louver structure region and the pillar structure region substantially coincides, the light diffusion incident angle region is a so-called narrow angle of incidence angle θ1=25 to 55°. The scope.

However, it was confirmed that the light-diffusing film of Example 2 has higher uniformity of diffused light than Comparative Examples 1 and 2 to be described later, and the spread of diffused light in the width direction of incident light is higher than that of Comparative Examples 3 and 4. Larger.

[Example 3]

In the third embodiment, the inclination angle of the louver structure was obtained in the same manner as in the first embodiment except that the θ3 of the first ultraviolet ray irradiation was changed to 40° and the incident angle of the parallel light irradiated by the second ultraviolet ray was changed to 0°. The light diffusion film shown in Fig. 17 (a) is 27° and the inclination angle of the column is 0°.

Further, as shown in FIGS. 17(b) to 17(h), the incident angle θ1 with respect to the light diffusion film is set to 0°, 10°, 20°, 30°, 40°, 50°, and 60°, respectively. The distribution of the spread of the diffused light and the luminance (%) thereof was measured in the same manner as in the first embodiment.

As a result, as shown in FIGS. 17(b) to 17(h), in the light-diffusing film of the third embodiment, although the incident angle θ1 of the incident light is about 20°, it is difficult to generate light diffusion, but the incident angle is 0. In the range of ~10°, isotropic light diffusion caused by the column structure region is generated, and anisotropic light diffusion caused by the louver structure region is generated in the range of the incident angle θ1=30 to 60°, so that it is known that The angle dependence of the light diffusion incident caused by the two structural regions is staggered, that is, the light diffusion incident angle region can be effectively enlarged.

[Example 4]

In the fourth embodiment, the inclination angle of the louver structure was obtained in the same manner as in the first embodiment except that the θ3 of the first ultraviolet ray irradiation was changed to 40° and the incident angle of the parallel light irradiated by the second ultraviolet ray was changed to 20°. The light diffusion film shown in Fig. 18(a) is 27° and the inclination angle of the pillar is 14°.

Further, as shown in FIGS. 18(b) to 18(g), the incident angle θ1 with respect to the light diffusion film is set to 5°, 15°, 25°, 35°, 45°, and 55°, respectively. In the same manner, the distribution of the spread of the diffused light and the luminance (%) thereof was measured in the same manner.

As a result, as shown in FIGS. 18(b) to 18(g), in the light diffusion film of the fourth embodiment, each of the column structure regions is generated in the range of the incident angle θ1 of the incident light of 5 to 25°. The isotropic light is diffused, and anisotropic light diffusion caused by the louver structure region occurs in the range of the incident angle θ1 = 25 to 55°. Therefore, it is understood that the angle dependence of the light diffusion incidence caused by the two structural regions is shifted. At the same time, a part of the repetition is repeated, that is, the light diffusion incident angle region can be effectively enlarged.

[Comparative Example 1]

In Comparative Example 1, except that the first ultraviolet ray irradiation was not performed, and the incident angle of the parallel light irradiated by the second ultraviolet ray was changed to 0°, the same operation as in the first embodiment was carried out, and as shown in FIG. 19(a), A light diffusion film having only a columnar structure having an inclination angle of 0° in the entire region of the first structural region and the second structural region.

Further, as shown in FIGS. 19(b) to (j), the incident angle θ1 with respect to the light diffusion film is set to 20°, 15°, 10°, 5°, 0°, -5°, -10, respectively. The distribution of the spread of the diffused light and the luminance (%) thereof were measured in the same manner as in Example 1 except for °, -15°, and -20°.

As a result, as shown in FIGS. 19(b) to 19(j), in the light diffusion film of Comparative Example 1, since only the column structure is provided, the light diffusion incident angle region is θ1=-15 to 15°, which is relatively narrow. range.

Further, the center portion of the diffused light is particularly brighter than the other portions, and it is understood that the uniformity of the diffused light is extremely low.

[Comparative Example 2]

In the second comparative example, except that the first ultraviolet ray irradiation was not performed, and the incident angle of the parallel light irradiated by the second ultraviolet ray was changed to 40°, the operation was performed in the same manner as in the first embodiment, as shown in FIG. 20(a). In the entire region of the first structural region and the second structural region, there is only a light diffusion film having a column structure having an inclination angle of 27°.

Further, as shown in FIGS. 20(b) to (k), the incident angle θ1 with respect to the light diffusion film is set to 15°, 20°, 25°, 30°, 35°, 40°, and 45°, respectively. The distribution of the spread of the diffused light and the luminance (%) thereof were measured in the same manner as in Example 1 except for 50°, 55°, and 60°.

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

Further, the center portion of the diffused light is particularly brighter than the other portions, and it is understood that the uniformity of the diffused light is relatively low.

[Comparative Example 3]

In the comparative example 3, except that the θ3 of the first ultraviolet ray irradiation was changed to 0°, and the second ultraviolet ray irradiation was not performed, the same operation as in the first embodiment was carried out, and as shown in FIG. 21(a), the first structure was obtained. The louver structure region in which the inclination angle of the region is 0° and the light diffusion film on the upper portion thereof which does not form the louver structure region.

Further, as shown in FIGS. 21(b) to (h), the incident angle θ1 with respect to the light diffusion film is set to 20°, 15°, 10°, 5°, 0°, -5°, -10, respectively. The distribution of the spread of the diffused light and the luminance (%) thereof were measured in the same manner as in Example 1.

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

In addition, the anisotropy of the diffused light is very large, and it is understood that the spread of the diffused light in the width direction of the incident light is small.

[Comparative Example 4]

In the comparative example 4, except that the θ3 of the first ultraviolet ray irradiation was changed to 40° and the second ultraviolet ray irradiation was not performed, the same operation as in the first embodiment was carried out, and as shown in FIG. 22(a), the obtained structure was obtained as the first structure. The louver structure region in which the inclination angle of the region is 27° and the light diffusion film on the region where the louver structure region is not formed.

22(b) to (i), the incident angle θ1 with respect to the light diffusion film is set to 25°, 30°, 35°, 40°, 45°, 50°, 55°, respectively. A light diffusion film was produced in the same manner as in Example 1 except for 60°.

Further, as shown in FIGS. 22(b) to (i), since the light diffusion film of Comparative Example 4 has only the louver structure, the light diffusion angle region is a so-called relatively narrow range of θ1 = 30 to 60°.

In addition, the anisotropy of the diffused light is very large, and it is understood that the spread of the diffused light in the width direction of the incident light is small.

As described in detail above, according to the present invention, a louver structure region for anisotropically diffusing incident light and a isotropic diffusion of incident light are provided in the film along the film thickness direction. The column structure region, that is, a light diffusion film having a good incident angle dependency and a wide light diffusion incident angle region can be obtained.

Therefore, the light diffusing film or the like of the present invention can be applied to a light control film of a reflective liquid crystal device, and can also be applied to a viewing angle control film, a viewing angle expansion film, and a projection screen, and it is expected that The high quality has produced a significant contribution.

The above-mentioned embodiments are merely examples for convenience of description, and the scope of the claims is intended to be limited to the above embodiments.

1. . . Coating layer

2. . . Engineering film

10. . . First structural region (anisotropic light diffusion film)

12. . . a plate-shaped region (high refractive index portion) having a relatively high refractive index

13. . . Louver structure

13’. . . Interface of blinds structure

14. . . a plate-shaped region (low refractive index portion) having a relatively low refractive index

20. . . Second structural region (isotropic light diffusing film)

twenty two. . . Column

twenty three. . . Column structure

twenty three'. . . Interface

twenty four. . . Medium with lower refractive index

30. . . Light diffusing film

50. . . Active energy ray

52,54,56,62,64,66. . . Incident light

52', 54', 56'62', 64', 66'. . . Diffused light

100. . . Reflective liquid crystal display device

101. . . Polarizer

102. . . Phase difference plate

103. . . Light diffuser

104. . . glass plate

105. . . Color filter

106. . . liquid crystal

107. . . Specular reflector

108. . . glass plate

110. . . Liquid crystal cell

120. . . Ultraviolet irradiation device

121. . . Infrared cut filter

122. . . Cold mirror

123. . . Shading

125. . . Linear UV lamp

202. . . point Light

204. . . lens

206. . . Linear UV lamp

208. . . Tube

210. . . Collection of cylinders

1103. . . Upper substrate

1105. . . Liquid crystal layer

1107. . . Lower substrate

1108. . . Light control board

1110. . . Light reflector

1112. . . Liquid crystal device

1121. . . Scattering axis direction

Θ1. . . Incident angle

Θ2. . . Opening angle

Θ3. . . Irradiation angle

Θ3’. . . Illumination angle width

Θa, Θb. . . Tilt angle

B. . . Conveyor movement direction

S1, S2. . . width

S3. . . The maximum diameter

L1, L3. . . length

L2, L4. . . width

1(a) to (b) are diagrams for explaining the outline of the louver structure of the first structural region.

2(a) to 2(b) are diagrams for explaining the angle dependence of the incident light and the anisotropy of the louver structure.

3(a) to (b) are other diagrams for explaining the incident angle dependency of the louver structure.

4(a) to 4(c) are diagrams for explaining the angles of incidence of the incident angle and the diffused light.

5(a) to 5(b) are diagrams for explaining the outline of the column structure of the second structural region.

6(a) to 6(b) are diagrams for explaining the incident angle dependency and isotropy of the column structure.

7(a) to 7(b) are diagrams for explaining the outline of the light diffusion film of the present invention.

8(a) to 8(c) are diagrams for explaining the form of the louver structure of the first structural region.

9(a) to 9(d) are diagrams for explaining the form of the column structure of the second structural region.

Fig. 10 is a view for explaining an application example of the light-diffusing film of the present invention in a reflective liquid crystal display device.

11(a) to 11(b) are diagrams for explaining the first active energy ray irradiation step.

12(a) to (b) are another diagrams for explaining the first active energy ray irradiation step.

13(a) to (c) are diagrams for explaining the second active energy ray irradiation step.

Figs. 14(a) to 14(k) are diagrams for explaining the spread of the diffused light and the distribution of the luminance of the light diffusing film of the first embodiment.

15(a) to 15(b) are photographs for explaining the cross section of the light diffusion film of Example 1.

Fig. 16 is a view for explaining the light diffusion film of Example 2.

17(a) to 17(h) are diagrams for explaining the spread of the diffused light and the distribution of the luminance of the light-diffusing film of Example 3.

18(a) to (g) are diagrams for explaining the spread of the diffused light and the distribution of the luminance of the light diffusing film of Example 4.

19(a) to (j) are diagrams for explaining the spread of the diffused light and the distribution of the luminance of the light-diffusing film of Comparative Example 1.

20(a) to (k) are diagrams for explaining the spread of the diffused light and the distribution of the luminance of the light diffusing film of Comparative Example 2.

21(a) to (h) are diagrams for explaining the spread of the diffused light and the distribution of the luminance of the light-diffusing film of Comparative Example 3.

22(a) to (i) are diagrams for explaining the spread of the diffused light and the distribution of the luminance of the light-diffusing film of Comparative Example 4.

23(a) to 23(b) are views for explaining a reflection type liquid crystal display device using a conventional light diffusion film.

10. . . First structural region (anisotropic light diffusion film)

20. . . Second structural region (isotropic light diffusing film)

30. . . Light diffusing film

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 in a single film, the first structural region a louver structure region in which a plurality of plate-like regions having different refractive indices are alternately arranged in parallel along the film surface direction, and the second structural region is formed in a plurality of columns having a refractive index different from the medium in the medium. The column structure area formed by the object. The light diffusion film according to claim 1, wherein in the first structural region, the width of the plate-like region having a different refractive index is set to a value within a range of 0.1 to 15 μm, and the plurality The plate-like regions are arranged in parallel at a certain inclination angle with respect to the film thickness direction. The light-diffusion film according to claim 1, wherein in the first structural region, a main component of the plate-like region having a high refractive index among the plate-shaped regions having different refractive indices contains a plurality of aromatic rings The polymer of (meth) acrylate, the main component of the plate-like region having a low refractive index is a polymer of urethane (meth) acrylate. The light-diffusing film according to claim 1, wherein the thickness of the first structural region is set to a value within a range of 5 to 495 μm. The light diffusion film according to claim 1, wherein in the second structural region, a maximum diameter of a cross section of the pillar is set to a value in a range of 0.1 to 15 μm, and the columnar shape is used. The distance between the objects is set to a value in the range of 0.1 to 15 μm, and the plurality of pillars are arranged at a constant inclination angle with respect to the film thickness direction. The light diffusion film according to claim 1, wherein in the second structural region, the main component of the pillar contains a plurality of (meth) acrylates of an aromatic ring, and the main component of the medium The composition is a urethane (meth) acrylate. The light-diffusing film according to claim 1, wherein the thickness of the second structural region is a value within a range of 5 to 495 μm. A method for producing a light diffusion film, comprising: a first structure region for anisotropically diffusing incident light in a single film; and a light diffusion film for a second structure region for isotropically diffusing incident light The manufacturing method includes the following steps (a) to (d): (a) a step of preparing a composition for a light-diffusing film; (b) applying the composition for a light-diffusing film onto an engineering sheet to form a coating a step of layering; (c) performing a first active energy ray irradiation on the coating layer, and forming a plurality of plate-like regions having different refractive indices as a first structural region along the film surface direction in a lower portion of the coating layer One hundred alternately arranged in parallel a leaf window structure region, and a step of not forming a louver structure region remaining in an upper portion of the coating layer; (d) performing a second active energy ray irradiation on the coating layer, forming a region in the region where the louver structure is not formed The second structural region is a step of forming a columnar structural region in which a plurality of pillars having a refractive index different from the medium are formed in a medium. The method for producing a light-diffusing film according to claim 8, wherein the second active energy ray is irradiated with parallel light having a parallelism of 10 or less.