KR20120099589A - Optical film - Google Patents

Abstract

PURPOSE: An optical film is provided to vary straight line penetration ratio of incident light according incidence angle. CONSTITUTION: A convex part(14a) parallelly arranges a photosensitive laminated body(10) on a lenticular lens(14) which is arranged lengthwise. The photosensitive laminated body comprises a dimorphism PET or a mask(18), a photo curing resin layer, and a transparent PET. UV parallel rays(12) are radiated from a normal direction of lenticular(14) toward the lenticular lens. The UV parallel rays pass through the lenticular lens and light(16) is diffused in a Y-direction from the convex part of the lenticular and the light is radiated to the photosensitive laminated body. The light is widely diffused in one direction through the lenticular lens and the light is narrowly diffused in a direction which is at right angles the one direction. The photosensitive laminated body is hardened when the light is radiated and forms a curable resin layer having an internal structure. [Reference numerals] (AA) X-direction; (BB) Y-direction

Description

Optical film {OPTICAL FILM}

TECHNICAL FIELD The present invention relates to an anisotropic diffusive optical film in which the diffusivity of transmitted light changes with incident angle.

The light diffusing member has not only been used in lighting fixtures and building materials before, but has also been widely used in displays, particularly LCDs, in recent years. The light diffusion expression mechanisms of these light diffusing members include scattering (surface scattering) due to irregularities formed on the surface, scattering (internal scattering) due to the difference in refractive index between the matrix resin and the filler dispersed therein, and both surface scattering and internal scattering. The thing by which is mentioned is mentioned. However, these light diffusing members are generally isotropic in their diffusing performance, and even if the incident angle is slightly changed, the diffusing characteristics of the transmitted light are not largely different.

(Type A with plate-like structure)

A light control panel is known which strongly diffuses incident light in a constant angle region and transmits incident light at an angle other than that (sold under the trade name "Lumisty" in Sumitomo Chemical. Patent Document 1, for example). This optical control panel irradiates and hardens parallel light using the linear light source from above the sheet-like photosensitive composition layer. And as shown in FIG. 15, in sheet-like base material, the board | substrate corresponded to the longitudinal direction of the linear light source 51 arrange | positioned above at the time of manufacture of the optical film 50, and differs in the refractive index from a peripheral area | region It is thought that the shape structures 40 are formed parallel to each other (hereinafter, referred to as type A for convenience). As shown in FIG. 16, a sample is arrange | positioned between the light source (not shown) and the light receiver 3, and a sample is sent straight through, while changing an angle with the straight line L of the sample surface as a central axis, and the light receiver 3 The linear transmittance to enter can be measured.

FIG. 17 shows the incident angle dependence of scattering characteristics of the optical film 50 of type A shown in FIG. 15 measured using the method shown in FIG. 16. The vertical axis represents the linear transmittance (the amount of light of the parallel light beam emitted in the same direction as the incident direction when the parallel light beam of predetermined amount of light is incident), which is an index indicating the degree of scattering, and the horizontal axis represents the angle of incidence. Solid lines and broken lines in FIG. 17 show a case where the optical film 50 is rotated around the AA axis (passes through the plate-like structure) and the BB axis (parallel to the plate-like structure) in FIG. 15, respectively. In addition, the plus and minus of an incident angle show that the direction which rotated the optical film 50 is reversed. Although the solid line in Fig. 17 remains low in linear transmission in the front direction and in the inclination direction, this means that the optical film 50 is scattered irrespective of the incident angle when rotated about the AA axis. Moreover, although the linear transmittance becomes small in the dashed line in the direction of 0 degree in FIG. 17, this means that an optical film is scattered with respect to the light of a front direction also when it rotates around a BB axis. In addition, although the linear transmittance increases in the direction where the incident angle is large, this means that the optical film is in a transmissive state with respect to the light in the oblique direction when rotated about the BB axis. Thanks to this structure, for example, the transmissivity varies depending on the incident angle in the horizontal direction, but the transmittance can be imparted even if the incident angle is changed in the vertical direction. Here, as shown in FIG. 17, a curve showing the incidence angle dependence of the scattering characteristics is referred to as an "optical profile". Although the optical profile does not directly express scattering characteristics, it can be said that the diffraction characteristics are generally exhibited when it is interpreted that the diffusion transmittance is increasing when the linear transmittance decreases.

(Type B with a columnar structure)

On the other hand, the optical film 60 having the columnar structure 62 which extends in the thickness direction (normal line direction P of the film) as described in FIG. For convenience, a type B is also proposed (for example, Patent Document 2). This columnar structure is formed in parallel in the advancing direction of the light in the photosensitive composition layer by irradiating UV light parallel to the photosensitive composition layer. In the optical film of this type B, the optical profile which shows the change of the linear transmittance at the time of changing an incident angle is shown in FIG. When A-A is the center of rotation and B-B is the center of rotation, the same optical profile is obtained in any case by measuring the linear transmittance by changing the incident angle. That is, the optical film of FIG. 18 exhibits almost the same linear transmittance even if the rotational center axis is changed, and the linear transmittance becomes a minimum once at an incident angle of ± 5 to 10 ° compared to the transmittance when incident in the normal direction (0 °). As the incident angle becomes larger, the linear transmittance increases, and the linear transmittance becomes the maximum at an incident angle of ± 45 to 60 °.

In more detail about these types A and B, in the case of an optical film having a fine structure composed of the height of the refractive index therein and the linear transmittance of the incident incident light transmitted according to the incident angle, the optical properties of the internal structure It is defined by the type and the slope of the structure. For example, in the case of the optical film in which the fine structure which differs in refractive index inside is formed in plate shape like the said Type A, the optical characteristic is prescribed | regulated by the inclination with respect to the film normal of the plate shape. On the other hand, in the case of the optical film which has a columnar structure extended in the thickness (normal) direction of a film like the said type B, an optical characteristic is prescribed | regulated by the inclination with respect to the film normal of the columnar structure. In the case of the type A optical film, incident light from a direction substantially parallel to the plate-like structure is strongly diffused, and since the light incident across the plate-like structure is transmitted through most of the light, the plate-shaped structure is called a light scattering surface. can do. On the other hand, in the case of an optical film of type B, the columnar structure is formed in parallel in the advancing direction of the light when irradiating parallel UV light to the photosensitive composition layer, and irradiates parallel UV light to the photosensitive composition layer from its normal direction. The columnar structure extends in the normal direction. In such a case, it becomes (the irradiation direction of UV light = the extending direction of a columnar structure = normal direction), and as shown in FIG. 19, the relationship between the angle of incidence of light in all incident surfaces and a linear transmittance is centered around a normal line. Since it is symmetric, this normal can be called a scattering central axis. This scattering central axis will be described in more detail with reference to the drawings.

20 shows a cross-sectional schematic diagram of the fine structure of an optical film of type B. FIG. A fine columnar structure extends in the normal direction of the sheet. Here, the area | region of a dot and the white area | region show the height of refractive index. The light diffusivity of this optical film can be easily irradiated by the method shown in FIG. In other words, when the optical film is fixed at regular intervals parallel to the white paper and a strong parallel ray such as a laser pointer is incident from the upper side with a specific area of the optical film as the incident point, the diffused state of the transmitted light is projected onto the white paper. Here, the incident light from the normal direction is projected as circular diffused light on the white paper, while the tilted incident light appears as a crescent-shaped projection light at a position away from the circular diffused light just before. The shape of the diffused light projected on the white paper when the inclination of the incident light and its orientation are changed is shown in FIG. 22. However, when the incident light is inclined little by little from the normal direction, as the inclination angle is deepened, the crescent shape becomes thinner and at the same inclination angle. When the orientation of incidence is changed, it can be seen that the direction of the new moon changes continuously even though the shape is the same. When the projection light shows a circle on a blank sheet, the straight line connecting the center of the circle and the incident point to the optical film at that time is the scattering center axis, which in this case coincides with the normal line.

On the other hand, when the extending direction of the columnar structure of Type B is inclined from the normal direction, the scattering central axis does not coincide with the normal direction. This inclined columnar structure is formed by irradiating UV light from the oblique direction with respect to the photosensitive composition layer, but with the extending direction of the columnar structure formed parallel to the incident direction of UV light and the UV light direction passing through the photosensitive composition layer. Does not necessarily match by Snell's law. Moreover, depending on the temperature conditions of the photosensitive composition layer at the time of UV light irradiation, a disorder may generate | occur | produce in the extending direction of a columnar structure, In this case also, a scattering central axis can be calculated | required by the method of FIG. 21 mentioned above. For example, when a diffusion pattern as shown in Fig. 23 is obtained, the scattering center axis is a straight line connecting the center of the substantially circular projection light and the incident point to the optical film at that time. In addition, when the area | region in which circular light is formed is not able to be discriminated, when the light which injected from the angle away from this scattering center axis | shaft diffused in crescent shape, as shown in FIG. 24, the straight line which bisects a crescent shape as shown in FIG. Since there is a scattering central axis on the extension line, the position of the scattering central axis can be obtained from the two crescents apart. That is, the straight line which connected the intersection of the 2 straight lines in FIG. 24, and the incidence point to the optical film at that time becomes a scattering center axis.

In addition, when the optical film of the plate-shaped structure of Type A is similarly measured by the method of FIG. 21, it will become like FIG. 25 and FIG. 25 shows the case where the plate-shaped structure is formed in the direction including the normal of the film. In this case, the diffused light has an elliptical shape extending in the X-axis direction on the Y-axis, and has a point shape with little spread at other incident angles. Here, the plate-shaped structure is located perpendicular to the X axis and extends in the Y axis direction. FIG. 26 shows the case where the plate-like structure is formed inclined from the normal direction of the film. Here too, the elongated elliptical spread is seen, but the ellipse is displayed along the Y ₁ axis tilted in the X-axis direction from the normal, and as the angle above Y ₁ changes, the elongated direction of the ellipse changes. In this case, the plate-like structure extends along the direction connecting the Y ₁ axis and the incident point of the optical film.

The optical film of type A which has a plate-shaped structure has a record of prevention of peek-proof construction, for example, and may be used for the purpose of expanding a viewing angle and improving visibility in a liquid crystal panel. On the other hand, the optical film of the type B which has a columnar structure can be used similarly for the use of a liquid crystal panel, and also the application to the screen for projectors is proposed. When using an anisotropic diffusion film for a liquid crystal panel, the type corresponding to a target viewing angle is selected according to a use. In reality, however, in Type A, the viewing angle of only one azimuth direction is enlarged, and the viewing angle is hardly enlarged in the azimuth direction orthogonal thereto.

Japanese Patent No. 2547417 Japanese Patent Application Laid-Open No. 2007-114756

In the case of Type A, since the change of the diffusivity when the incident angle of light is changed is very severe, when it is applied to a panel, it may become a sudden change of visibility and may give an unnatural feeling. On the other hand, in Type B, the viewing angle is enlarged almost equally in all directions, but it is not possible to meet the requirement to further enlarge the viewing angle in some part of the direction (for example, in the horizontal direction), and the attempt to enlarge the diffusion angle lowers the front luminance. . In order to improve these problems, it is also proposed to use it in combination with other diffusion films, but from the demand of cost and the simplification of a manufacturing process, it was desired to have intermediate optical characteristics of these optical films. Accordingly, an object of the present invention is to provide an optical film having both the above-described properties of type A and type B on the basis of the prior art.

This invention (1) is an optical film in which the fine structure which consists of the height of the refractive index exists inside, and the linear transmittance of the incident light which transmits differs according to an incident angle,

Circular light incident from the scattering central axis has a property of projecting in an elliptical shape with respect to a plane parallel to the optical film,

The scattering characteristics of the light incident from the scattering central axis

The relationship between the X axis on the optical film plane in the direction parallel to the long axis direction of the ellipse and the emission angle in the plane formed by the scattering central axis and the diffusion transmittance at this emission angle (Tx), and

The relationship (Ty) between the Y-axis on the optical film plane perpendicular to the X-axis and the emission angle in the plane formed by the scattering central axis and the diffusion transmittance at this emission angle is

The peak width (F _{max1 / 10} x) at a tenth value from the maximum value of the diffusion transmittance peak in the relationship (Tx) and one tenth from the maximum value of the diffusion transmittance peak in the relationship (Ty). It is an optical film characterized by peak value (F _{max1 / 10y} ) satisfy | _fills the relationship of following formula (1) in a value.

1.5 <F _{max1 / 10} x / F _{max1 / 10} y <4.5 ... (1)

The present invention (2) has a relationship between the incident angle of light in the plane formed by the X axis and the scattering central axis and the linear transmittance.

The maximum value F _A (%) of the linear transmittance and the angle A (°) taking the maximum value, the minimum value F _B (%) of the linear transmittance and the angle B (°) taking the minimum value satisfy the relationship of the following formula (2) It is an optical film of said invention (1) to say.

0.70 <(F _A -F _B ) / | AB | <2.0 ... (2)

This invention (3) shows that the said microstructure appears in the cross section parallel to the plane which the X-axis and the scattering center axis of the said optical film form, and the cross section parallel to the plane which the Y-axis and scattering center axis of the said optical film form. It is an optical film of said invention (1) or (2) characterized by the above-mentioned.

In the present invention (4), the density of the fine structure in the cross section parallel to the X-axis scattering central axis plane of the optical film is higher than the density of the fine structure in the cross section parallel to the Y-axis scattering center axis plane. It is an optical film of the said invention (3) characterized by the above-mentioned.

In this invention (1), since it has the fine structure which consists of height of refractive index inside, the optical film of this invention can make the linear transmittance of the incident light which permeate | transmits change with an incident angle. In addition, circular light incident from the scattering central axis is projected in an ellipse with respect to a plane parallel to the optical film. The light is strongly diffused in the long axis direction of the ellipse, and the light is diffused lightly in the short axis direction orthogonal to the long axis. Or it combines the characteristics of both the plate-shaped structure of the said type A and the columnar structure of the said type B, and provides the characteristic which was not acquired unless a conventionally two or more different anisotropic conversion films are used. Specifically, by preferentially diffusing light in the required direction, it becomes possible to substantially increase the utilization efficiency of light.

In the present invention (2), since the change in diffusivity when changing the angle of incidence of light is gentle as compared with the type A known so far, when it is applied to a panel, there is no sudden change in visibility and a more natural impression (印象) can be given to the observer.

In the present invention (3), the circular light incident from the scattering center axis is elliptical with respect to the plane parallel to the optical film, and the plane formed by the X axis and the scattering center axis, and the plane formed by the Y axis and the scattering center axis. Since a fine structure is formed on the surface, scattering in the X-axis direction and scattering in the Y-axis direction can be simultaneously performed, and the diffusion degree in the X-axis direction and the diffusion degree in the Y-axis direction have different properties. can do.

In the present invention (4), since the density of the fine structure is different depending on the X-axis direction and the Y-axis direction, light diffusion can be made different according to the direction in which light is emitted.

BRIEF DESCRIPTION OF THE DRAWINGS The conceptual diagram of the optical profile which the optical film of this invention has is shown.
2 shows a conceptual diagram of an optical profile of the optical film of the present invention.
3 shows a conceptual diagram of properties of the optical film of the present invention.
4 shows a method for obtaining the scattering central axis of the optical film of the present invention.
5 shows a method for obtaining the scattering central axis of the optical film of the present invention.
Fig. 6 shows a schematic diagram of the Gonio offset measurement experiment.
7 shows the anisotropic diffusion property of the optical film of the present invention.
Fig. 8 shows a cross-sectional photograph of the optical film of the present invention produced by irradiating UV light in the normal direction of the film surface.
9 shows a cross-sectional photograph of an optical film of the present invention prepared by irradiating UV light in a direction inclined by 10 ° from the normal direction of the film surface.
FIG. 10 shows a cross-sectional photograph of an optical film of the present invention prepared by irradiating UV light in a direction inclined at 45 ° from the normal direction of the film plane.
11 shows a schematic view of one embodiment during production of the optical film of the present invention.
12 shows a schematic diagram of one embodiment during the manufacture of the optical film of the present invention.
13 shows the measurement results of the optical profile (linear transmittance) relating to the optical films of the examples of the present invention and the comparative examples.
14 shows the measurement results of the anisotropic diffusivity (diffusion transmittance) of the optical films of Examples and Comparative Examples of the present invention.
Fig. 15 shows a schematic diagram of an optical film (having a plate-like structure) of the type A of the prior art.
16 shows a measuring method of an optical profile.
17 shows an optical profile of a type A optical film of the prior art.
FIG. 18 shows a schematic diagram of an optical film (having a columnar structure) of Type B of the prior art.
19 shows the optical profile of an optical film of the type B of the prior art.
20 shows a cross-sectional schematic diagram of an optical film of Type B of the prior art.
21 shows a method for detecting scattering central axis.
Fig. 22 shows the diffusion state of the optical film of the type B of the prior art (when UV irradiation in the normal direction).
Fig. 23 shows the diffusion state of the optical film of the type B of the prior art (when irradiated with UV in the oblique direction).
24 shows a method for detecting scattering central axis.
Fig. 25 shows the diffusion state of the optical film of the type A of the prior art (when UV irradiation in the normal direction).
Fig. 26 shows the diffusion state of the optical film of Type A of the prior art (when irradiated with UV in the oblique direction).

Here, the definition of each term in this claim and this specification is demonstrated.

The "fine structure which consists of height of refractive index" means the structure formed by the height difference of the local refractive index of the material which comprises an optical film. For example, FIG. 8 is an optical film according to Example 3. FIG. As shown in Fig. 8, the fine structure is a structure that forms an optically observed shape in cross section. These structures are formed when the material forming the optical film is cured, and it is estimated that the structures are formed by, for example, a difference in height and density.

The "scattering central axis" means a direction in which the scattering characteristic coincides with the incident angle of light having substantially objectivity with respect to the incident angle when the incident angle is changed. Here, having substantially objectivity is because, when the scattering central axis has an inclination with respect to the normal direction of the film plane, optical properties described later do not have objectivity strictly. The scattering central axis can be found by observing the projection shape of the circular light through the optical film by changing the incident angle as described later. Hereinafter, the scattering center axis will be described. First, the spatial positioning of the scattering central axis has been described using FIGS. 21 to 26. However, if the azimuth direction of the inclination of the scattering central axis obtained by this is known, the optical profile is measured in the plane formed by the normal line. The exact tilt angle of the central axis can be obtained. In this optical profile, the scattering central axis can be represented by the angle of incidence in which the local maximum is introduced between two local minimums. 1 and 2 conceptually show various optical profiles and scattering central axes. First, FIG. 1 is an optical film produced by irradiating UV light in the normal direction of the film, which is an optical profile (W type) in which the overall shape is approximately symmetrical. The thick vertical line coinciding with 0 degrees is the incident angle coinciding with the scattering central axis in this case. FIG. 2 is an optical film produced by irradiating UV light from a direction different from the normal direction of the film, wherein the overall shape is an optical profile (W-type) that is not a left or right object. Here too, the thick vertical line passing between the local maximum Fc between the two local minimums is the incident angle coinciding with the scattering central axis in this case. As such, in any case, the scattering central axis is determined by first noting the large valley area that is approximately symmetrical and then specifying the center of the valley area. 1 and 2, the valley area includes local minimums on the left and right sides, and includes local maximums between the local minimums. The position of this maximum value becomes the scattering central axis. In addition, in the case where the optical profile is not a W type having a local maximum between two local minimums and a U type where the local maximum is hardly seen in a large valley area, the flat portion of the valley bottom is almost the same distance from the inclined surfaces of both bones. The vicinity of the center of can be defined as the scattering central axis. Moreover, when an optical profile shows a V shape, the deepest part of the center of the valley can be defined as the scattering central axis.

The linear transmittance is related to the linear transmittance of light incident on the optical film, and is expressed by the following formula as a ratio of the amount of transmitted light in the linear direction and the amount of incident light when incident from an incident angle.

Linear transmittance (%) = (Linear transmitted light amount / incident light amount) × 100

The present invention is an optical film in which a fine structure made up of the height of the refractive index exists inside, and the linear transmittance of the incident incident light is different depending on the incident angle. That is, it is an optical film which has anisotropic diffusion property. The optical film of this invention gives the same property as the middle of the property which the said plate-shaped structure of type A and the columnar structure of said type B give. EMBODIMENT OF THE INVENTION Hereinafter, the content of this invention is demonstrated using a 1st aspect and a 2nd aspect.

(First Embodiment)

In 1st aspect, the content of this invention is demonstrated, for example, when a scattering center axis is parallel to the normal direction of an optical film. It is a conceptual diagram for demonstrating the optical characteristic of the optical film which concerns on this invention. In FIG. 3, (1) is an optical film of this invention, (2) is a plane parallel to an optical film. As shown in Fig. 3, the optical film according to the present invention has the property that the circular light incident at the position of P from the scattering central axis is projected in an ellipse with respect to the plane 2 parallel to the optical film. Here, circular light means that the shape of a vertical cross section becomes circular shape. Although it does not specifically limit as circular light, For example, lasers, such as a laser pointer, are mentioned.

The elliptical light projected on the parallel plane 2 has long axis A-A 'and short axis B-B'. The elliptical shape is a projected form in which the circular light is diffused in the X-axis direction and is extended in the long axis A-A 'direction, and the circular light is expanded in the short axis B-B' direction as the circular light is diffused in the Y-axis direction. That is, projecting in an ellipse means that the degree of diffusion in the X-axis direction and the Y-axis direction of the optical film is different. In this way, not only the difference in diffusivity depending on the direction, but also in the present invention, the constant light diffusion can be observed even in the direction of the uniaxial B-B '.

4 shows scattering characteristics when the scattering central axis is in the normal direction as in the optical film of the present embodiment. That is, FIG. 4 is a diagram showing the form of light projected on the plane 2 when the incident angle is changed as the light transmitted through the point P in FIG. 3. The optical film of the present invention has a scattering central axis described in the rod-shaped structure part because it aims at the optical properties in the middle between the plate-like structure and the rod-shaped structure. As shown in Fig. 4, the central diffusion shape is elliptical. In this way, the incident angle forming the central diffusion shape coincides with the scattering central axis. However, it is rounder than the ellipse shown in Fig. 25, and the diffused shape of the oblique incident light also has an intermediate shape between the crescent of Fig. 22 and the elliptical shape of Fig. 25. As explained above, even if the irradiation direction of UV light in manufacture is not known, the scattering center axis of an optical film can be grasped only by using a simple apparatus, such as a laser pointer. In addition, when it is difficult to find a scattering central axis, the method shown in FIG. 24 can be applied, and since the scattering central axis exists on the extension line of the straight line which divides a crescent shape, the position of a scattering central axis can be calculated | required from two crescents which fell apart. .

In the present invention, a particularly remarkable characteristic appears in the scattering characteristics of light incident from the scattering central axis. The relationship between the peak width of the relationship Tx showing the scattering characteristic in the X-axis direction and the relationship Ty showing the scattering characteristic in the Y-axis direction satisfies the predetermined relationship. That is, from the maximum value of the peak of the diffusion transmittance in the said relationship (Tx) from the peak width ( _{Fmax1 / 10x} ) at a _tenth value, and from the maximum value of the peak of the linear transmittance in the said relationship (Ty) The peak width (F _{max1 / 10y} ) at the _tenth value satisfies the relationship of the following formula (1).

1.5 <F _{max1 / 10} x / F _{max1 / 10} y <4.5... (One)

The peak width (F _{max1 / 10} ) reflects the scattering properties of the optical film. By setting the ratio of the peak widths to such a range, the difference between the scattering characteristics in the X-axis direction and the Y-axis direction is appropriately adjusted.

Here, the relationship (Tx) is a relationship between the emission angle in the plane formed by the X axis on the optical film plane and the scattering central axis, and the diffusion transmittance at this emission angle.

In addition, relationship (Ty) is a relationship between the emission angle in the plane which the Y-axis on an optical film plane, and the said scattering center axis | shaft form, and the diffusion transmittance in this emission angle.

In particular, in the present invention, it is more suitable to satisfy the following characteristics.

2.0 <F _{max1 / 10} x / F _{max1 / 10} y <3.0

About the scattering characteristic of the optical film of this invention, it evaluates by the method shown in FIG. 6 using a Goniometer. Light is irradiated to the optical film of this invention, and the transmittance | permeability of the light radiate | emitted from a film is measured. The measurement is performed by rotating the light receiver around the light source in the X direction (up and down direction from the ground) and the Y direction (just in front of the ground and inward direction).

7 shows the scattering characteristics of the optical film of Example 2 described later. In FIG. 7, the horizontal axis is used as the angle of the detector with respect to the optical film, and the vertical axis is represented by the transmittance defined below.

Diffusion transmittance = (detected light amount of detector / detected light amount when detector is placed in front of light source without optical film) x 100

In Fig. 7, the relationship (T _x ) between the emission angle in the plane formed by the X axis and the scattering center axis and the diffusion transmittance at the emission angle is indicated by a broken line (X axis direction), and the Y axis and the scattering center axis are shown. The relationship (T _Y ) between the emission angle in the formed plane and the diffusion transmittance at the emission angle is indicated by a solid line (Y-axis direction). F _{max1 / 10} x is the peak width at a tenth value (X axis max1 / 10) from the maximum value (X axis max) of the peak of the diffusion transmittance of the relationship (T _x ). On the other hand, _{Fmax1 / 10} Y is the peak width at the tenth value (Y-axis max1 / 10) from the maximum value (Y-axis max) of the peak of the diffusion transmittance of the relationship (Ty).

In the optical film of the present invention, the relationship between the incident angle of light in the plane formed by the X axis and the scattering central axis and the linear transmittance (%) is taken as the maximum value F _A (%) of the linear transmittance and the maximum value. It is very suitable that the angle A (°), the minimum value F _B (%) of the linear transmittance and the angle B (°) taking the minimum value satisfy the following expression (2).

0.70 <(F _A -F _B ) / | AB | <2.0.. (2)

By satisfying such a characteristic, the angle dependency of linear transmittance is alleviated. For example, when used in a display can solve the problem that the image quality changes rapidly depending on the angle.

In particular, in the present invention, it is more suitable to satisfy the following characteristics.

0.90 <(F _A -F _B ) / | AB | <1.7

Here, angles A and B mean angles with respect to the normal of the optical film. About this relationship, returning to FIG. 1, the relationship (optical profile) of the incidence angle of light in a optical film of this invention and linear transmittance is demonstrated in detail. The optical profile of the optical film of the present invention forms a curve that is approximately symmetrical about the scattering central axis. The curve has three local maxima and two local minima. That is, when linearly transmitted light is measured by changing the incidence angle, the two portions have minimum values F _B1 and F _B2 respectively (in addition, the incidence angle formed by the minimum value F _B1 is B ₁ and the incidence angle formed by the minimum value F _B2 is B _2. .). There is a relatively small maximum value Fc at positions between the minimum values. The angle of incidence at the local maximum coincides with the scattering central axis. On both sides of the maximum value Fc, there exists a maximum value F _A1 and a maximum value F _A2 between the minimum values F _B1 and F _B2 between the maximum values Fc (an incidence angle consisting of the maximum value F _A1 is set to A ₁ and the maximum value F _A2 is determined. A ₂ ).

Equation (2) between each two kinds of the maximum value at (F _A1 and F _A2) and a minimum value according to (F _B1 and F _B2), to (a), (b) that of two greater than the value F _A and A , F _B and B.

(a) (F _A1 -F _B1 ) / | A ₁ -B ₁ |

(b) (F _A2 -F _B2 ) / | A ₂ -B ₂ |

That is, the larger the slope from the local minimum to the local maximum in the optical profile is used. Under these conditions, the optical film of the present invention satisfies the relationship of the formula (2). In addition, the measuring method of an optical profile is as having described in the said background art and FIG.

8 is a cross-sectional photograph of an optical film of the present invention. FIG. 8 (A) is a cross-sectional photograph in a direction parallel to the X-axis scattering central axis plane, and FIG. 8 (B) is a cross-sectional photograph of a direction parallel to the Y-axis scattering center axis plane. As shown in Fig. 8, in the cross section in the X-axis direction, a fine structure composed of the height and the refractive index of the micrometer unit appears as the vertical stripes. On the other hand, although it appears that a fine structure exists in the Y-axis direction cross section orthogonal to it, the said structure may not be confirmed. As is clear from this photograph, the density of the fine structure in the cross section parallel to the X-axis scattering central axis plane of the optical film of the present invention, and the density of the fine structure in the cross section parallel to the Y-axis scattering center axis plane In comparison, the former is higher than the latter. That is, in the optical film of the present invention, the fine structure is densely present in one direction, and the light is diffused strongly, while the fine structure is sparse in the direction orthogonal thereto, and the light is thought to be weakly diffused.

(Second Embodiment)

The 2nd aspect which concerns on this invention is an optical film which has the inclination which a scattering center axis does not correspond with the normal direction of an optical film. 5 shows scattering characteristics when the scattering central axis is inclined in the Y-axis direction, but FIG. 5 is projected onto the plane 2 when the incident angle is changed as light passing through the P point in FIG. It is a figure which shows the form of the light which becomes. This also shows the intermediate property of FIG. 22 and FIG. In any case, the diffusive shape in the case where light is incident by changing the incident angle represents a form with high symmetry from circular to elliptical, and the incident angle of scattered light having the central ellipse coincides with the scattering central axis.

Also in a 2nd aspect, although a scattering center axis | shaft differs from the normal direction of an optical film, it shows the same scattering characteristic and optical profile as a 1st aspect.

It is a cross-sectional photograph of the optical film produced by irradiating UV-ray tilted 10 degrees from the normal line direction of a film surface. Also in this case, a fine structure composed of the height of the refractive index of the stripes is formed in the X-axis direction (Fig. 9 (A)), but almost no fine structure is confirmed in the Y-axis direction (Fig. 9 (B)) orthogonal thereto. Do not.

10 is a cross-sectional photograph of an optical film produced by irradiating UV rays tilted at 45 degrees from the normal direction of the film surface. Also in this case, a fine structure is formed in the X-axis direction (Fig. 10 (B)) consisting of the height of the refraction of the remarkable stripes, but the fine structure can be confirmed in the Y-axis direction (Fig. 10 (A)) orthogonal thereto. However, compared to the X-axis direction, it becomes a thin stripe.

Manufacturing method of optical film

The optical film of this invention can be produced by giving UV irradiation to specific photocurable resin layer on special conditions. Hereinafter, the raw material of an optical film is demonstrated first, and then a manufacturing process is demonstrated.

Raw material of optical film (photocurable compound)

The photocurable compound, which is a material for forming the optical film of the present invention, is composed of a photopolymerizable compound and a photoinitiator selected from a polymer, an oligomer, and a monomer having a radical polymerizable or cation polymerizable functional group, and an ultraviolet ray and / or a visible ray. It is a material which polymerizes and solidifies by irradiating light.

A radically polymerizable compound mainly contains one or more unsaturated double bonds in a molecule, and specifically, epoxy acrylate, urethane acrylate, polyester acrylate, polyether acrylate, poly butadiene acrylate, silicone acrylate, etc. Acryl oligomer called by name, 2-ethylhexyl acrylate, isoamyl acrylate, butoxyethyl acrylate, ethoxy diethylene glycol acrylate, phenoxy ethyl acrylate, tetrahydrofurfuryl acrylate, isonorbornyl Acrylate, 2-hydroxy ethyl acrylate, 2-hydroxy propyl acrylate, 2-acryloyloxyphthalic acid, dicyclopentenyl acrylate, triethylene glycol diacrylate, neopentyl glycol diacrylate, 1, 6-hexanediol diacrylate, bisphenol A EO adduct diacrylate, trimethylolpropane triacrylate, EO modified trimethylol propane triacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, ditrimethylol propane tetraacrylate, dipentaerythritol Acrylate monomers, such as hexaacrylate, are mentioned. In addition, these compounds may be used alone or in combination. Moreover, although methacrylate can also be used similarly, since acrylate is generally faster than a methacrylate, since photopolymerization speed is preferable, it is preferable.

As a cationically polymerizable compound, the compound which has 1 or more of an epoxy group, a vinyl ether group, and an oxetane group can be used in a molecule | numerator. Examples of the compound having an epoxy group include 2-ethylhexyl diglycol glycidyl ether, biphenyl glycidyl ether, bisphenol A, hydrogenated bisphenol A, bisphenol F, bisphenol AD, bisphenol S, tetramethyl bisphenol A Diglycidyl ethers of bisphenols such as tetramethyl bisphenol F, tetrachloro bisphenol A, tetrabromo bisphenol A, phenol novolacs, cresol novolacs, brominated phenol novolacs, ortho cresol novolacs and the like Polyglycidyl ethers, ethylene glycol, polyethylene glycol, polypropylene glycol, butanediol, 1,6-hexanediol, neopentyl glycol, trimethylolpropane, 1,4-cyclohexanedimethanol, EO adducts of bisphenol A Diglycidyl ethers of alkylene glycols such as PO adducts of bisphenol A, glycidyl esters of hexahydrophthalic acid, and diglycidyl esters of dimer acid Cynyl esters are mentioned.

3,4-epoxycyclohexyl methyl-3 ', 4'-epoxycyclohexane carboxylate, 2- (3,4-epoxycyclohexyl-5,5-spiro-3,4-epoxy) cyclohexanemethadi Oxane, di (3,4-epoxycyclohexylmethyl) adipate, di (3,4-epoxy-6-methylcyclohexylmethyl) adipate, 3,4-epoxy-6-methylcyclohexyl-3 ', 4 '-Epoxy-6'-methylcyclohexanecarboxylate, methylenebis (3,4-epoxycyclohexane), dicyclopentadiethanediepoxide, di (3,4-epoxycyclohexylmethyl) ether of ethylene glycol, Ethylenebis (3,4-epoxydicyclohexanecarboxylate), lactone modified 3,4-epoxycyclohexylmethyl-3 ', 4'-epoxycyclohexanecarboxylate, tetra (3,4-epoxycyclohexylmethyl) butane Alicyclic epoxy compounds, such as tetracarboxylate and di (3, 4- epoxycyclohexylmethyl) -4, 5- epoxy tetrahydrophthalate, are also mentioned, Information that is not.

As a compound which has a vinyl ether group, For example, diethylene glycol divinyl ether, triethylene glycol divinyl ether, butanediol divinyl ether, hexanediol divinyl ether, cyclohexane dimethanol divinyl ether, hydroxybutyl vinyl ether, Although ethyl vinyl ether, dodecyl vinyl ether, trimethylol propane trivinyl ether, propenyl ether propylene carbonate, etc. are mentioned, It is not limited to these. Moreover, although a vinyl ether compound is generally cationically polymerizable, radical polymerization is also possible by combining with an acrylate.

As the compound having an oxetane group, 1,4-bis [(3-ethyl-3-oxetanylmethoxy) methyl] benzene, 3-ethyl-3- (hydroxymethyl) -oxetane and the like can be used.

In addition, the above cationically polymerizable compound may be used individually, or may be mixed and used for it. The photopolymerizable compound is not limited to the above. Moreover, in order to produce a sufficient refractive index difference, as said photopolymerizable compound, you may introduce a fluorine atom (F) in order to aim at low refractive index, and a sulfur atom (S), a bromine atom ( Br) and various metal atoms may be introduced. In addition, as disclosed in Japanese Patent Laid-Open No. 2005-514487, an acryl group or methacryl is formed on the surface of ultrafine particles made of high refractive index metal oxides such as titanium oxide (TiO ₂ ), zirconium oxide (ZrO ₂ ), and tin oxide (SnO _x ). It is also effective to add the functional ultrafine particles which introduced photopolymerizable functional groups, such as group and an epoxy group, to the photopolymerizable compound mentioned above.

Raw material of optical film (optical Initiator )

As a photoinitiator which can superpose | polymerize a radically polymerizable compound, benzophenone, benzyl, Michler's ketone, 2-chloro thioxanthone, 2, 4- diethyl thioxanthone, benzoin ethyl ether, benzo Phosphorus isopropyl ether, benzoin isobutyl ether, 2,2-diethoxyacetophenone, benzyldimethyl ketal, 2,2-dimethoxy-1,2-diphenylethan-1-one, 2-hydroxy-2- Methyl-1-phenylpropan-1-one, 1-hydroxycyclohexyl phenyl ketone, 2-methyl-1- [4- (methylthio) phenyl] -2-morpholinopropanoone-1,1- [4 -(2-hydroxyethoxy) -phenyl] -2-hydroxy-2-methyl-1-propan-1-one, bis (cyclopentadienyl) -bis (2,6-difluoro-3- (Pil-1-yl) titanium, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butanone-1,2,4,6-trimethylbenzoyldiphenylphosphine oxide, etc. In addition, these compounds may be used individually, or may be mixed and used for them.

The photoinitiator of a cationically polymerizable compound is a compound which generates an acid by light irradiation and can polymerize the above-mentioned cationically polymerizable compound by the generated acid, and generally an onium salt and a metallocene complex are preferably used. do. Onium salts include diazonium salts, sulfonium salts, iodide salts, phosphonium salts, is used, such as serenyum salts thereof counter ion is BF ₄ ^- is an anion such as ^{_{-, PF 6 -, AsF 6}} -, SbF 6 Is used. Specific examples include 4-chlorobenzenediazonium hexafluorophosphate, triphenylsulfonium hexafluoroantimonate, triphenylsulfonium hexafluorophosphate, (4-phenylthiophenyl) diphenylsulfonium hexafluoroantimony Monate, (4-phenylthiophenyl) diphenylsulfonium hexafluorophosphate, bis [4- (diphenylsulfonio) phenyl] sulfide-bis-hexafluoroantimonate, bis [4- (di Phenylsulfonio) phenyl] sulfide-bis-hexafluorophosphate, (4-methoxyphenyl) diphenylsulfonium hexafluoroantimonate, (4-methoxyphenyl) phenyliodium hexafluoroantimo Nate, bis (4-t-butylphenyl) iodonium hexafluorophosphate, benzyltriphenylphosphonium hexafluoroantimonate, triphenylcerenium hexafluorophosphate, (η5-isopropyl benzene) (η5-cyclopenta Diethyl) iron (II) hexafluorophosphate, and the like. However, it is not limited to these. In addition, these compounds may be used alone or in combination.

Raw material of optical film (mixture amount, other optional components)

In this invention, the said photoinitiator mix | blends 0.01-10 weight part, Preferably it is 0.1-7 weight part, More preferably, it is about 0.1-5 weight part with respect to 100 weight part of photopolymerizable compounds. This is because when less than 0.01 weight part, photocurability falls, and when it mix | blends more than 10 weight part, only the surface hardens and the internal hardenability falls, and it causes the inhibition of formation of coloring, columnar structure. Although these photoinitiators are normally used by directly dissolving powder in a photopolymerizable compound, when the solubility is bad, you may use the thing which melt | dissolved the photoinitiator in a very small amount of solvent previously in high concentration. It is more preferable that it is photopolymerizable as such a solvent, Specifically, a propylene carbonate, (gamma) -butyrolactone, etc. are mentioned. Furthermore, in order to improve photopolymerizability, it is also possible to add various well-known dye and sensitizer. Moreover, the thermosetting initiator which can harden a photopolymerizable compound by heating can also be used together with a photoinitiator. In this case, by heating after photocuring, the polymerization hardening of a photopolymerizable compound can be accelerated | stimulated further and it can be expected to make it perfect.

In this invention, the anisotropic diffused layer can be formed by hardening the composition which mixed the said photocurable compound individually or in plurality. Moreover, the anisotropic diffusion layer of this invention can also be formed by hardening the mixture of a photocurable compound and the polymer resin which does not have photocurability. Polymer resins that can be used here are acrylic resins, styrene resins, styrene acrylate copolymers, polyurethane resins, polyester resins, epoxy resins, cellulose resins, vinyl acetate resins, vinyl chloride-acetic acid copolymers, and polyvinyl butyrates. Lal resin etc. are mentioned. Although these polymer resins and photocurable compounds need to have sufficient compatibility before photocuring, in order to ensure this compatibility, various organic solvents, a plasticizer, etc. can also be used. In addition, when using an acrylate as a photocurable compound, it is preferable from a compatible point to select from an acrylic resin as a polymer resin.

[process]

Next, the manufacturing method (process) of the optical film of this invention is demonstrated. The photocurable composition mentioned above is coated on a suitable base material, such as a transparent PET film, and a coating film (photocuring resin layer) is provided. Although it dries as needed and volatilizes a solvent, the dry film thickness is 10-200 micrometers, More preferably, it is 20-100 micrometers, More preferably, it is 25-50 micrometers. If the dry film thickness is less than 10 µm, the light diffusivity obtained through the UV irradiation process described later is not preferable. On the other hand, when the dry film thickness exceeds 200 micrometers, it is unpreferable from the point that the diffusivity of the whole is too strong and it becomes difficult to obtain the characteristic anisotropy of this invention, and it is unsuitable for cost increase and thinning use. Moreover, on this coating film, a release film and a mask mentioned later are laminated and a photosensitive laminated body is produced.

(Method of providing a composition containing a photocurable compound in a sheet form on a substrate)

Here, as a method of providing the composition containing a photocurable compound in a sheet form on a base | substrate, the normal coating system and the printing system are applied. Specifically, air doctor coating, bar coating, blade coating, knife coating, reverse coating, transfer roll coating, gravure roll coating, kiss coating, cast coating, spray coating, slot orifice coating, calender coating, dam coating, dip coating, Coating such as die coating, intaglio printing such as gravure printing, printing such as stencil printing such as screen printing, and the like can be used. When the composition has a low viscosity, a dam of a constant height may be provided around the gas, and the composition may be cast in the enclosure surrounded by the dam.

(Lamination of Masks)

In order to form the microstructure which is the characteristic of the optical film of this invention efficiently, it is also possible to laminate | stack the mask which adheres closely to the light irradiation side of a photocurable composition layer, and changes the irradiation intensity of light locally. As a material of the mask, a light absorbing filler such as carbon is dispersed in a polymer matrix, and a part of incident light is absorbed by carbon, but the opening is preferably one in which light can be sufficiently transmitted. Moreover, only by laminating | stacking a normal transparent film on a photocurable composition layer, it is effective in preventing oxygen interference and promoting formation of a columnar body.

(Light source)

As a light source for irradiating light to a composition containing a photocurable compound, a short arc ultraviolet light source is usually used. Specifically, a high pressure mercury lamp, a low pressure mercury lamp, a metahalide lamp, a xenon lamp, or the like can be used. The light ray irradiated to the composition containing a photocurable compound needs to contain the wavelength which can harden | cure this photocurable compound, and the light of the wavelength centering on 365 nm, such as a mercury lamp, is used normally.

In order to make the parallel light beam 12 from the light from the UV light of the short arc, for example, a reflector is arranged behind the light source, and the light is emitted as a point light source in a predetermined direction, or the light is Fresnel. Parallel light can be obtained by a lens (Fresnel lenz). A Fresnel lens is a lens obtained by dividing a normal lens into concentric circular regions to reduce thickness, and having a sawtooth-shaped cross section. When the light beam emitted from the point light source passes through the Fennel lens, the direction of the light in which the direction is scattered is unified in one direction and becomes a parallel light beam. However, in order to obtain the parallel UV output light which is necessary in manufacturing the optical film of this invention, it does not necessarily require a fennel lens, It turns out that it uses various methods including a laser.

(1) irradiation of UV rays according to the normal

In order to produce the optical film of the present invention, the above-mentioned photosensitive laminate is irradiated with UV light from the normal film direction from the release film or mask side, but both of the diffused light lines diffused in one direction therewith without the parallel light beam described above. It is important to investigate both at the same time. In order to irradiate such a light beam, a lenticular lens can be used, for example. The UV parallel rays can pass through the lenticular to form the rays (rays that are diffused in one direction with the parallel rays). In this case, the lenticular may only be a light source diffused in one direction (parallel light rays may be mixed somewhat). Moreover, an exposure mask can also be combined with a lenticular lens. The lenticular lens refers to a lens having a plurality of semi-cylindrical or arc-shaped elongated convex portions having convex portions arranged in parallel, and having opposite sides of the convex portions being flat surfaces (hereinafter, for convenience, the "semi-cylinder" Elongated convex portion of a shape or arc shape ”is called a fish cake (middle convex) shape).

Here, in the example using a lenticular lens, the above "irradiating both parallel rays and diffused rays diffused in one direction" means that the convex portion of the lenticular lens having a fish cake shape in parallel is an element. It is understood that the light rays spread out in the shape (spread in the plane fan shape) are arranged in parallel in the longitudinal direction (parallel in the diffusion plane).

11 shows one embodiment of the method for producing the optical film of the present invention. The photosensitive laminated body 10 (release PET or mask 18 from the side close to a lens, and photocurable resin layer in parallel with the lenticular lens 14 in which the convex part 14a which is a semi-circle pillar with a horizontal length is parallel in a vertical direction) (20) and transparent PET (22) are arrange | positioned, UV parallel light ray 12 is irradiated toward the lenticular lens 14 from the normal direction of the lenticular 14, and photocured. When UV light passes through the lenticular lens 14, the light 16 diffuses in the Y direction from the convex portion 14a of the lenticular and is irradiated to the photosensitive laminate 10. Through a lenticular lens, it takes a wide spread in one direction (Y direction in FIG. 11, the inner direction of the paper), and has a narrow diffusion in the direction orthogonal to this (X direction in FIG. 11, vertical direction of the paper). Anisotropic light 16 which does not have is formed. The photosensitive laminated body 10 is photocured when irradiated, and it becomes a cured resin layer which has an internal structure in a photocurable resin layer.

(2) Irradiation of UV rays not in the normal direction

As each aspect, you may irradiate a photosensitive laminated body by inclining a parallel light ray from the direction different from a normal line direction. An example of that aspect is shown in FIG. The parallel light beam 12 (which has an angle of 60 ° from the lenticular lens) inclined 30 ° from the normal direction of the lenticular lens 14 is opposite to the convex surface (fish-shaped surface) 14a of the lenticular lens. Investigate from In that case, the diffused light 16 is irradiated in the oblique direction from the convex surface 14a of the lenticular lens. As a result, the diffused light 16 is irradiated from the inclined direction of the photosensitive laminated body 10 spreading in a planar fan shape centering on the direction inclined 30 degrees to the X-axis from the normal of the photosensitive laminated body as shown in the figure, and photocured Photocuring is performed in layer 20.

In addition, the above-mentioned UV irradiation method using a lenticular lens is one method for producing the optical film of this invention, and this invention is not limited to this. The point is that in order to form a specific internal structure in the photocurable composition layer, it is important to irradiate the photosensitive laminate with UV light diffused in a planar sector shape.

That is, the fine structure which consists of the height of the refractive index which concerns on this invention is formed by the process of irradiating the light-curable resin layer with the diffusivity to planar fan shape. Moreover, the light to irradiate has a wavelength which can harden the said photosensitive composition. Moreover, in the process to irradiate, it is suitable to use the light which spread the parallel light ray in planar fan shape.

When manufacturing the optical film of this invention, it is preferable that the illuminance of the UV light irradiated to the photosensitive laminated body through the lenticular lens mentioned above is 0.01-100 mW / cm <^2> , More preferably, it is 0.1-20. mW / cm ² . If the illuminance is 0.01 mW / cm ² or less, the production efficiency is poor because curing requires a long time, and if it is 100 mW / cm ² or more, the curing of the photocurable compound is too fast, resulting in no formation of the structure, thereby achieving the desired anisotropic diffusion characteristics. This is because it cannot be expressed.

Although irradiation time of UV is not specifically limited, It is for 10 to 180 second, More preferably, it is for 30 to 120 second. Then, the anisotropic diffused optical film of this invention can be obtained by peeling a release film.

As described above, the optical film of the present invention can be obtained by forming a specific internal structure in the photocurable composition layer by irradiating low illuminance UV light for a relatively long time. For this reason, such UV irradiation alone may cause unreacted monomer components to remain sticky, resulting in problems in handling and durability. In such a case, it is possible to polymerize the remaining monomer by further irradiating UV light of high illuminance of 1000 mW / cm ² or more. It is preferable to perform UV irradiation at this time from the opposite side to a mask side.

Example

According to the following method, the optical film of this invention and the optical film of a comparative example were manufactured.

Example  1 vertical probe

On the 100-micrometer transparent PET film, the photocurable composition of the prescription shown in Example 3 of Unexamined-Japanese-Patent No. 2005-514487 is coated, the coating film with a dry film thickness of 50 micrometers is provided, and also 38 micrometers on this coating film. The release PET film of was laminated so that the release surface was in contact with the coating film. Parallel UV light (formed using a Fresnel lens) of 5 mW / cm ² from the direction of 0 ° with respect to the normal from the release PET film side of the laminate, the radius (r) = 0.5 mm, the pitch (p) = 0.5 mm It was irradiated for 90 seconds through the lenticular lens (installed so that it might be parallel with a laminated body). The optical film (transparent PET / photocuring resin layer) of this invention was obtained by peeling a release PET film from the laminated body after hardening (refer FIG. 11). The UV rays irradiated through the lenticular lens were mostly parallel without scattering in the X direction (vertical direction of the ground), but became scattered rays in the Y direction (inward direction of the ground).

Example  2 vertical probe

The optical film (transparent PET / photocuring resin layer) of this invention was obtained like Example 1 except having set the lenticular lens to be used as radius (r) = 0.5 mm, and pitch (p) = 0.7 mm.

Example  3 vertical probe

Instead of the release PET film, the lenticular lens was radiused using an exposure mask having an optical density (OD) of 0.50 obtained by applying and drying a polyvinyl alcohol resin aqueous solution obtained by dispersing graphite particles having an average particle diameter of 3 μm on a PET film. The optical film (transparent PET / photocuring resin layer) of this invention was obtained like Example 1 except having set to (r) = 0.05mm and pitch (p) = 0.1mm.

Example  4 tilt probe

An optical film (transparent PET / photocured resin layer) of the present invention was obtained in the same manner as in Example 2 except that the direction to be irradiated was inclined by 30 ° from the normal direction of the laminate to the X axis side (see FIG. 12). Moreover, the lenticular lens and the laminated body were provided so that it might become parallel, UV light irradiated through the lenticular lens was inclined by 30 degrees in the X direction, and became parallel and scattered light in the Y direction.

Comparative example  One

Except not using a lenticular lens, it carried out similarly to Example 1, and obtained the comparative optical film (transparent PET / photocuring resin layer). Since it does not pass through a lenticular lens, a perfect parallel ray is irradiated, and the optical film which has a columnar fine structure of type B was obtained.

Comparative example  2

Commercially available Lumisti (registered trademark Sumitomo Chemical) was used as an optical film having a plate-like fine structure of type A.

Evaluation 1 Comparison of Optical Profiles (Linear Transmittance)

About the incident angle dependency, it evaluated by the method using the Konio photometer (GENESIA Gonio / Far Field Profiler made from Genesia) shown in FIG. Obtained by arranging a sample between a light source (not shown) and the light receiver 3, and measuring the linear transmittance of the sample passing through the sample linearly and entering the light receiver 3 while varying the angle around the straight line L of the sample surface. (In addition, the detail of a measuring method is described in Paragraph No. 0048 of Unexamined-Japanese-Patent No. 2005-265915.). The results for Examples 1 to 3 and Comparative Examples 1 and 2 are shown in FIG. 13. In addition, since the result of Example 2 is the same as that of Example 1, it states together. According to this result, the optical films of Examples 1, 2, and 3 have a local maximum near 30 degrees which are normal directions, take the minimum value F _B as an incident angle B of ± 5-10 degrees, and further expand the incident angle therefrom. , The maximum value F _A is taken as an incident angle A around 40 to 50 °. From the optical profile obtained by the measurement, (F _A -F _B ) / | AB | was calculated and shown in Table 1.

Evaluation 2 Receiver  Diffusion Permeability When Rotated

The anisotropy of diffusion was evaluated by the method shown in FIG. 6 using a Goniometer. Using the optical film manufactured by the said Example and the comparative example, light was irradiated and the transmittance | permeability of the light radiate | emitted from the film was measured. Also in the measurement, the light receiver was rotated in the X direction (up and down direction from the ground) and the Y direction (just in front of and inside of the ground) around the emission point of the light from the optical film in FIG. 6. The results are shown in FIG. F _{max1 / 10} x / F _{max1 / 10} y was calculated and shown in Table 1.

Claims (4)

As an optical film in which a fine structure composed of the height of the refractive index exists inside and the linear transmittance of the incident incident light is different depending on the incident angle,
Circular light incident from the scattering central axis has a property of projecting in an elliptical shape with respect to a plane parallel to the optical film,
The scattering characteristics of the light incident from the scattering central axis
The relationship between the X-axis on the optical film plane in the direction parallel to the long axis direction of the ellipse and the emission angle in the plane formed by the scattering central axis and the diffusion transmittance at this emission angle (Tx), and
The relation Ty between the Y axis on the optical film plane perpendicular to the X axis and the emission angle at the plane formed by the scattering central axis and the diffusion transmittance at this emission angle is
Peak width (F _{max1 / 10x} ) at the tenth value from the maximum value of the diffusion transmittance peak in the relationship (Tx), and one tenth from the maximum value of the diffusion transmittance peak in the relationship (Ty). The peak film (F _{max1 / 10y} ) in the value satisfies the relationship of the following formula (1).
1.5 <F _{max1 / 10} x / F _{max1 / 10} y <4.5... (One) The method according to claim 1,
The relationship between the incident angle of light in the plane formed by the X axis and the scattering central axis and the linear transmittance is
The maximum value F _A (%) of the linear transmittance and the angle A (°) taking the maximum value, the minimum value F _B (%) of the linear transmittance, and the angle B (°) taking the minimum value satisfy the relationship of the following formula (2) Optical film characterized in that.
0.70 <(F _A -F _B ) / | AB | <2.0.. (2) The method according to claim 1 or 2,
The fine film is characterized in that the fine structure appears in a cross section parallel to the plane formed by the X axis and the scattering central axis of the optical film and a plane parallel to the plane formed by the Y axis and the scattering center axis of the optical film. The method according to claim 3,
The density of the said fine structure in the cross section parallel to the X-axis scattering center axis plane of the said optical film is higher than the density of the said fine structure in the cross section parallel to a Y-axis scattering center axis plane.

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