WO2020054689A1 - Resin film, and method for producing resin film - Google Patents

Abstract

The purpose of the present invention is to provide: a resin film suitable for use in a light guide plate, mainly in view of the problem of controlling surface shape; and a method for producing the same. The foregoing is solved by: this resin film that has a surface in which the percentage of the area of an inclined region having an inclination angle of at least 0.3 degrees is not more than 10%; and this method for producing the resin film, including a melt extrusion step for melt-extruding a resin material for the resin film.

Description

Resin film and method for producing resin film

The present invention relates to a resin film, particularly a resin film suitable for use as a light guide plate, and a method for producing the same.

2. Description of the Related Art Light guide plates that diffuse and transmit light for illumination are used in liquid crystal display devices such as tablet PCs and smartphones (for example, Patent Documents 1 and 2). When light from a light source enters the side surface of the light guide plate, the light guided inside the light guide plate exits from the light exit surface, and the emitted illumination light is used for illumination.

In a light guide plate, it is necessary to efficiently and uniformly emit illumination light from a light emitting surface. That is, the light guide plate plays a role not only to diffuse the illumination light but also to finally emit the light. For this reason, the light-emitting surface of the light guide plate usually formed of resin, that is, the surface having the largest area in the film is controlled in surface shape so that the illumination light is emitted efficiently and uniformly. .

JP 2000-258633 A JP 2004-200093 A

As described above, it is necessary to control the surface shape of the light guide plate, but it is not always easy to control the surface shape of the light guide plate. For example, in a process of obtaining a final product of a light guide plate from a resin film, it may be difficult to manufacture a light guide plate having a desired surface shape depending on a state of a resin film used as a material, particularly, a surface state thereof.

The present invention has been made in view of the above circumstances. That is, the present invention provides a resin film suitable for use as a light guide plate and a method for producing the same, mainly from the viewpoint of controlling the surface shape.

The present invention relates to a resin film described below and a method for producing the same.

(1) A resin film in which the ratio of the area occupied by the inclined region having an inclination angle of 0.3 ° or more on the surface is 10% or less.
(2) The resin film according to (1), wherein a ratio of an area occupied by the inclined region on the surface is 0.01% or more.
(3) The resin film according to the above (1) or (2), wherein a ratio of an area occupied by an inclined region having an inclination angle of 0.2 degrees or more on the surface is 30% or less.
(4) The resin film according to any one of (1) to (3), wherein an area occupied by an inclined region having an inclination angle of 0.15 degrees or more on the surface is 45% or less.
(5) The resin film according to (1) to (4), wherein the surface has a surface roughness value of 5.0 nm or less based on ISO 25178.
(6) The resin film according to (5), wherein the value of the surface roughness Sa on the surface is 1.0 nm or more.
(7) The resin film according to any one of the above (1) to (6), wherein the dYI value based on ASTM E313-05 is 0.8 or less.
(8) The resin film according to any one of the above (1) to (7), wherein the resin film is produced by a melt extrusion method.
(9) The resin film according to (8), wherein the melt extrusion method includes a melt extrusion step of melt-extruding a resin material of the resin film.
(10) polycarbonate (PC), acrylic resin, polyethylene terephthalate (PET), triacetyl cellulose (TAC), polyethylene naphthalate (PEN), polyimide (PI), cycloolefin polymer (COP), cycloolefin copolymer (COC), The resin film according to any one of the above (1) to (7), comprising a resin containing at least one of a norbornene-containing resin, polyether sulfone, cellophane, and an aromatic polyamide.
(11) The resin film according to (10), wherein the acrylic resin contains polymethyl methacrylate (PMMA).
(12) A light guide plate having a surface corresponding to the surface of the resin film according to any one of (1) to (11) as a light exit surface.
(13) The method for producing a resin film according to any one of the above (1) to (11), further comprising a melt extrusion step of extruding a resin material of the resin film.
(14) The above-mentioned (13), wherein a roll having an uneven shape formed on the surface such that the ratio of the area occupied by the inclined region having an inclination angle of 0.3 ° or more is 5% or less is used in the melt extrusion step. The method for producing a resin film according to (1).

According to the present invention, it is possible to provide a resin film capable of accurately controlling the surface shape when used for manufacturing a light guide plate, a method for manufacturing the same, and the like.

FIG. 4 is a diagram illustrating a method for calculating a tilt angle on a film surface. It is sectional drawing which expands and shows the surface of a resin film schematically. It is a perspective view which shows the manufacturing process of a resin film schematically. It is an image of the surface of the resin film of an Example. It is an image of the surface of the resin film of the comparative example. FIG. 3 is a view showing measurement data of the surface shape of the film of Example 1. FIG. 7A is a diagram showing the undulation image obtained in Example 1 and displayed on the monitor of the analyzer, and FIG. 7B is a view showing each of the swell images obtained by the analysis relating to Example 1. FIG. 7 is a diagram illustrating a relationship between a pixel inclination angle and a frequency.

Hereinafter, the present invention will be described in detail. It should be noted that the present invention is not limited to the following embodiments, and can be arbitrarily modified and implemented within the scope of the present invention.

The shape of the surface of the resin film of the present invention is controlled as described in detail below, and the surface of the resin film has high smoothness. In addition, in this specification, the surface of a film does not include the side surface with a very small area, but means the surface with the largest area in the film.
Further, the light guide plate of the present invention is at least processed to make the surface of the resin film rougher, and is derived from the resin film. The present invention further includes a method for producing the above resin film.

[Resin film]
The resin film of the present invention has a surface with high smoothness, and is particularly suitable as a material for a plate-like member requiring further control of the surface shape, for example, a light guide plate.

<Resin film shape>
The surface shape of the resin film is controlled so that the ratio of the area occupied by the inclined region having an inclination angle of 0.3 ° or more is 10% or less. Here, assuming that the area occupied by the inclined region on the surface of the resin film is the inclination ratio, the inclination ratio is the surface area of the inclined region when a region having an inclination angle of 0.3 ° or more on the surface of the resin film is defined as the inclined region. Corresponds to the proportion of the entire surface of the resin film.

測定 Measure the surface shape of the film to calculate the slope of the film surface. Examples of an apparatus for measuring the surface shape include a contact type surface roughness meter and a non-contact type surface roughness meter (for example, a white interference microscope, a confocal microscope, an atomic force microscope, etc.). Among these, a scanning white interference microscope is preferable from the viewpoint of simplicity of measurement. A specific example of such a scanning white light interference microscope is VS-1550 (Hitachi High-Tech Science).

In order to calculate a tilt rate using a scanning white interference microscope or the like, first, a tilt angle θ at each point on the film surface is determined. The calculation method of the inclination angle θ is as follows.
When one of two orthogonal directions on the measurement surface of the film is defined as the x-axis and the other is defined as the y-axis, the inclination of the point on the film surface in the x-axis direction with respect to the x-axis and the inclination in the y-axis direction with respect to the y-axis are determined. . Assuming that the value of the inclination in the x-axis direction is tan θx (hereinafter also referred to as Sx) and the value of the inclination in the y-axis direction is tan θy (hereinafter also referred to as Sy), these values are obtained from the following equations (1) and (2). Is calculated.
tan θx = (Z2-Z1) / Δx (1)
tanθy = (Z3-Z1) / Δy (2)
In equations (1) and (2),
As shown in FIG. 1A, Z1 is the height (Z-axis value) of the pixel A on which the inclination angle θ on the film is measured,
Z2 and Z3 are the height (Z-axis value) of pixel B adjacent to pixel A on the x-axis direction side and the height (ZZ) of pixel C adjacent to pixel A on the y-axis direction side, respectively. Axis value)
Δx and Δy are the sizes of one pixel in the x-axis and y-axis directions, respectively.

　こうして算出されたｔａｎθｘｙ（傾斜Ｓｔ：Ｓｔ^２＝（Ｓｘ^２＋Ｓｙ^２））の値を、下記式（４）により傾斜角θの値に換算する。
　θ＝ｔａｎ^－１（ｔａｎθｘｙ）　　…（４）
　このような演算により、フィルム表面上の多数の点における傾斜角θｉの値が算出され、傾斜角データが得られる。 Further, the value of the tilt angle tanθxy (hereinafter, also referred to as tilt St) of the pixel A in the xy direction is obtained by the following equation (3).

The value of tan θxy (inclination St: St ² = (Sx ² + Sy ² )) thus calculated is converted into the value of the inclination angle θ by the following equation (4).
θ = tan ⁻¹ (tan θxy) (4)
By such an operation, the values of the inclination angles θi at many points on the film surface are calculated, and the inclination angle data is obtained.

Based on the tilt angle data thus obtained, the ratio of the tilt region in which the absolute value of the tilt angle θi is 0.3 degrees or more is calculated as the tilt rate. That is, since the absolute value is a region having a tilt angle θi of 0.3 degrees or more, the ratio of the total area of the portion defined as the tilt region to the total surface area of the film is calculated as the above-described tilt ratio. Here, the total area of the inclined region is the sum of the total surface area (area of the inclined surface) of the inclined region for the convex region and the total surface area (area of the inclined surface) of the inclined region for the concave region.
For example, on the surface of the resin film 10 illustrated in FIG. 2, the area other than the convex area 12 is a flat area 10A, and if the inclination angle α is 0.3 degrees or more, the surface of the convex area 12 on the side of the inclined surface 12A is The total area is calculated as the area of the inclined region, and if the inclination angle β is less than 0.3 degrees, the surface of the convex region 12 on the inclined surface 12B side does not correspond to the inclined region. Although not shown in FIG. 2, the inclination angle of the concave area and the inclined area are determined in the same manner as the convex area 12. That is, a region where the inclination angle, which is the angle between the extension surface S and the inclined surface of the not-shown concave region, is 0.3 ° or more is also defined as the inclined region.

Then, the sum of the surface areas of the convex regions exemplified in the convex regions 12, the sum of the surface areas of the concave regions not shown, and the sum of the areas of the flat regions exemplified as 10A are calculated as the total surface area of the resin film. You. Further, the total of the areas of the inclined regions included in the convex region and the concave region is calculated, and the ratio of the total area of the inclined regions (total area of the inclined regions) to the total surface area of the resin film is calculated as the inclination ratio. Is done.

In the resin film, as described above, the value of the specified gradient is 10% or less, and the value of the gradient is preferably 9% or less, more preferably 5% or less, and still more preferably 2% or less. is there.
On the other hand, the value of the gradient in the resin film is, for example, 0.01% or more, but since a defect due to high smoothness is basically not recognized, the lower limit of the gradient is smaller than 0.01%. It may be a value.

The inclination rate when a value smaller than the above-mentioned 0.3 degree was determined as the inclination angle threshold was also examined. For example, except that the inclination angle threshold is 0.2 degrees, in the resin film in the case of defining the inclination rate as described above, the proportion of the area occupied by the inclination region having an inclination angle of 0.2 degrees or more, It is preferably at most 30%, more preferably at most 26%, further preferably at most 10%, particularly preferably at most 5%.
In addition, except that the threshold value of the inclination angle is 0.15 degrees, in the resin film in which the inclination ratio is defined as described above, the ratio of the area occupied by the inclination region having the inclination angle of 0.15 degrees or more is: It is preferably at most 45%, more preferably at most 44%, further preferably at most 20%, particularly preferably at most 12%.

On the surface of the resin film, the value of the surface roughness Sa according to ISO 25178 is preferably 5.0 nm or less, more preferably 4.5 nm or less, and still more preferably 3.5 nm or less, Particularly preferably, it is 3.0 nm or less.

As described above, it can be said that a resin film having a small area occupied by the inclined region and preferably having a small surface roughness Sa has high surface smoothness. Thus, the resin film having a smooth surface is suitably used in applications in which a predetermined pattern of irregularities is formed on the surface by further processing.
It is preferable that both surfaces of the resin film, that is, both surfaces have the above-described shape, but only one surface may have the above-described shape.

樹脂 The resin film of the present invention is particularly suitably used as a material for a light guide plate having a surface with irregularities. The reason for this is that, as will be described later in detail, in the resin film of the present invention, light emission from the surface is minimized even when light is guided from the end (side surface) to guide the light. Can be If the light guide plate is formed using such a resin film as a material, the desired light output performance as the light guide plate is ensured by processing to design the uneven shape suitable for causing the guided light to exit from the light exit surface as designed. It is because it is exhibited.

As described above, in the present invention, the surface shape of the resin film is controlled based on the ratio of the area occupied by the inclined region having the specific inclination angle, and more preferably, the surface shape is controlled based on the value of the surface roughness Sa. It is possible to suppress light emission from the light source. On the other hand, it was difficult to suppress light emission from the surface of the resin film based on other parameters, for example, Ra (line roughness) specified in JIS B 0601: 2013. That is, even if the value of Ra is adjusted to evaluate a resin film having a small value of Ra, it is not always possible to suppress the light emission from the resin film surface, and the correlation between the Ra value and the light emission suppression is not sufficient. I was not able to admit. As described above, it was confirmed that the control of the surface shape based on the ratio of the area occupied by the inclined region, more preferably the value of the surface roughness Sa, is particularly suitable for suppressing light emission from the surface.

The thickness of the resin film is not particularly limited, but is preferably 50 μm to 3000 μm (3.0 mm), more preferably 70 to 2000 μm, further preferably 100 to 1000 μm, and particularly preferably 100 to 700 μm. .

<Material of resin film>
The material of the resin film is not particularly limited, but preferably contains a thermoplastic resin. Examples of the thermoplastic resin include polycarbonate (PC) resin, acrylic resin containing polymethyl methacrylate (PMMA), polyethylene terephthalate (PET), triacetyl cellulose (TAC), polyethylene naphthalate (PEN), polyimide (PI), Various resins such as olefin polymer (COP), cycloolefin copolymer (COC), norbornene-containing resin, polyether sulfone, cellophane, and aromatic polyamide are used. The resin film preferably contains at least a polycarbonate resin among these options.

As the type of the polycarbonate resin, a-[OR-OCO] -unit containing a carbonate bond in a molecular main chain (R is an aliphatic group, an aromatic group, or both an aliphatic group and an aromatic group) Is not particularly limited, as long as it contains a bisphenol A skeleton or a bisphenol C skeleton. Polycarbonates are particularly preferred. As the polycarbonate resin, a mixture of bisphenol A and bisphenol C or a copolymer may be used. By using a bisphenol C-based polycarbonate resin, for example, a polycarbonate resin of bisphenol C alone, a mixture of bisphenol C and bisphenol A, or a copolymer polycarbonate resin, the hardness of the resin film can be improved.

For a thermoplastic resin forming a resin film, for example, a polycarbonate resin, the viscosity average molecular weight is preferably from 10,000 to 40,000, more preferably from 15,000 to 32,000, and still more preferably from 15 to 32,000. 2,000 to 28,000.

樹脂 Moreover, the resin film may contain an additive as a component other than the thermoplastic resin. For example, it is at least one additive selected from the group consisting of a heat stabilizer, an antioxidant, a flame retardant, a flame retardant auxiliary, an ultraviolet absorber, a release agent, and a colorant. Further, an antistatic agent, a fluorescent whitening agent, an anti-fogging agent, a fluidity improver, a plasticizer, a dispersant, an antibacterial agent and the like may be added to the resin film.

The resin film preferably contains the thermoplastic resin in an amount of 80% by mass or more, more preferably 90% by mass or more, and particularly preferably 95% by mass or more. Further, the thermoplastic resin of the resin film preferably contains at least 80% by mass of a polycarbonate resin, more preferably at least 90% by mass, particularly preferably at least 95% by mass. .
Further, the resin film is preferably formed of a uniform component, and preferably does not include particles such as light-transmitting fine particles, non-uniform phases, and the like.

<Properties of resin film>
In the resin film, the dYI value based on ASTM E313-05 is preferably 0.8 or less, more preferably 0.7 or less, and further preferably 0.6 or less. In this manner, by suppressing the dYI value to a low value, yellowing of the film end surface when the resin film is guided can be suppressed, so that a resin film particularly suitable as a light guide product can be realized. Then, in order to reduce the dYI value of the resin film, it is preferable that the step of manufacturing the resin film, for example, the step of melting the resin pellets of the material or the like be performed in an inert gas atmosphere. It is preferable to use nitrogen gas as the inert gas.

In the resin film, it is preferable to suppress light emission from the surface (light emission surface) in a state where light is emitted from the side surface to guide the light. Specifically, it is preferable that the luminance value of the surface (light emitting surface) measured under the following conditions is 70 (Cd / m ² ) or less. That is, light from an LED arranged to be in contact with an end (side surface) of a resin film sample having a size of 12 cm (length) × 12 cm (width) × 0.47 mm (thickness). Is a luminance value measured by a luminance meter (manufactured by Konica Minolta, LS-110) at an angle of 20 degrees with respect to the film surface in a state where the film is irradiated with light.

The luminance value measured under the above conditions is more preferably 60 (Cd / m ² ) or less, further preferably 50 (Cd / m ² ) or less, and particularly preferably 40 (Cd / m ² ) or less. It is. In the method of evaluating the luminance value, more preferably, the light guide direction of the light from the LED is set to the MD direction (the direction in which the resin flows when the resin film is formed) and the TD direction (perpendicular to the MD direction). The same sample is measured by four methods with the measurement surface as the front surface and the back surface, and the maximum luminance value is evaluated.

白 It is preferable that whiteness on the surface is not observed in a state where light is guided to the resin film. For example, light from an LED arranged to be in contact with an end (side surface) of a resin film sample having a size of 12 cm (length) × 12 cm (width) × 0.47 mm (thickness). It is preferable that whiteness of the film surface is not visually recognized in a state where the film is irradiated with light.

[Light guide plate]
<Shape of light guide plate>
In a light guide plate manufactured using a resin film as a material, a predetermined shape according to the use of the light guide plate, such as a hemispherical uneven shape or a prism shape, is formed on a light emitting surface corresponding to the surface of the resin film. As described above, in the resin film of the present invention, since light emission from the surface is suppressed to a minimum, if a predetermined surface shape is formed on the light guide plate manufactured from the resin film, light emission as designed can be obtained. It is easily possible. Therefore, the light guide plate of the present invention has a feature that the light guide performance can be reliably controlled.

<Material of light guide plate>
The material of the light guide plate is not particularly limited. However, since the light guide plate is formed using a resin film, the same material as the above-described resin film is preferable.

[Production method of resin film]
The resin film of the present invention is preferably produced by a melt extrusion method. This is because surface smoothness can be easily and reliably realized.
As described above, the extrusion molding using the melt extrusion method is performed, for example, according to the following steps. Pellets, flakes, or powdered resin materials are melted by an extruder, kneaded, and extruded from a T-die or the like, and the resulting semi-molten sheet is cooled and solidified while being pressed by a roll to form a sheet. It is a process.

Further, as described above, in producing a resin film by a production method including a melt extrusion step, it is preferable to adjust the surface shape of a roll, usually a metallic roll, which presses the resin material in the melt extrusion step. This is for reliably producing a resin film having a highly smooth surface.
Specifically, the gradient rate defined in the same manner as the above-described gradient rate of the resin film, that is, the ratio of the area of the inclined region having an inclination angle of 0.3 ° or more to the area of the roll surface is 5% or less. It is preferable to use a roll having a surface on which an uneven shape is formed. On the roll surface used in the melt extrusion step, the value of the gradient is more preferably 4% or less, further preferably 1% or less, and particularly preferably 0.5% or less. The proportion occupied by the area of the inclined region having an inclination angle of 0.2 ° or more on the roll surface is preferably 25% or less, more preferably 21% or less, and further preferably 10% or less. Preferably, it is particularly preferably at most 5%. Further, the proportion of the area of the inclined region having an inclination angle of 0.15 degrees or more on the roll surface is preferably 42.5% or less, more preferably 42% or less, and more preferably 20% or less. More preferably, it is particularly preferably 12% or less.

On the surface of the roll used in the melt extrusion step, the value of the surface roughness Sa according to ISO 25178 is preferably 7.0 nm or less, more preferably 5.0 nm or less, and still more preferably 4.0 nm. Or less, particularly preferably 3.0 nm or less.
As will be described in detail later, the surface shape of the roll can be approximated by measuring the surface shape of a roll replica formed by curing a resin on the roll surface, and then measuring the same.

(4) A method for producing a resin film will be described with reference to FIG. 3, which schematically illustrates a melt extrusion step. The manufacturing apparatus 20 used for manufacturing the resin film includes a die 22 for housing and extruding the resin material, a rectangular extrusion port 24 formed in the die 22, a first roll 30, a second roll 32, and A third roll 34 is included. The first to third rolls 30, 32, and 34 are all preferably made of metal.

The first and second rolls 30 and 32 are arranged below the extrusion port 24 and are arranged so as to sandwich the resin material 40 extruded from the extrusion port 24 before molding. The third roll 34 is arranged on the side of the second roll 32. The first to third rolls 30, 32, and 34 rotate in the directions indicated by the arrows in FIG. 3, and the resin material 40 is stretched while being mainly shaped by the second roll 32, and the unfinished resin The film 42 is obtained. Then, the unfinished resin film 42 is subjected to cutting, finishing, and the like, whereby a resin film is manufactured.

Among the first to third rolls 30, 32, and 34, the one that most affects the surface shape of the resin material 40 is to press the front surface (the surface shown in FIG. 3) of the resin film 42. This is the second roll 32. Therefore, prior to the production of the resin film, it is necessary to perform a step of smoothing the surface of the second roll 32 below and below the extrusion port 24 of the die 22 so that the gradient of the surface is sufficiently low. preferable.

Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the following embodiments, and can be arbitrarily modified and implemented without departing from the gist of the present invention.

<Create role replica>
In order to measure the surface shape of the metal roll, a transparent replica of the surface of the metal roll was prepared using UV-curable resin GLX18-73N manufactured by Glue Lab. That is, the above resin was cured on the surface of the metal roll to obtain a replica, and the surface shape of the transparent replica was measured and determined to be equal to the surface shape of the metal roll.

<Method of measuring the gradient of the surface of the film and the roll replica>
The measurement of the gradient of the surface of the film and the roll replica, that is, the measurement of the ratio of the area occupied by the total of the inclined regions having an inclination angle of 0.3 ° or more to the total surface area of the film, is performed by the following (i) surface shape. And (ii) measuring the area ratio.

(I) Acquisition of surface shape (device used)
White interference microscope: Scanning white interference microscope VS-1550 (Hitachi High-Tech Science) Measurement software: VS-Measure
(Optical conditions)
Camera: Sony XCL-C30 1/3
Camera speed: 1.0X
Objective lens: 50XDI
Lens tube: 1X
Zoom lens: 1X
Light source: 530 white
(Measurement condition)
Measuring device: Piezo Measuring mode: Wave
Scan speed: 4um / sec
Field of view size: 640 x 480
Scan range (um)
Start: 10
Stop: -10
Effective pixels: 70%
Average count: 1
The measurement is performed under the above conditions, and the surface shape data of the film is obtained. The area of the visual field obtained at this time was 94 μm × 71 μm, the value of Δx in the above equation (1) was 0.147 μm, and the value of Δy in the above equation (2) was 0.148 μm.

(Ii) Measurement of tilt angle Analysis software: VS-Viewer
The film surface shape data obtained according to the method (i) is analyzed and measured using the analysis software VS-Viewer by the following operations, and an in-plane inclination angle of 0.3 ° or more is occupied. The area ratio was measured.
Operation 1. The file of the surface shape data targeted for the measurement of the inclination angle was opened.
FIG. 6 shows a screen displayed on the monitor of the apparatus by the analysis software VS-Viewer as a result of the operation 1 in Example 1 described below. On the screen showing the actual surface shape data in FIG. 6, the horizontal axis indicates the length of the X-axis (μm) in the viewing area, and the vertical axis indicates the length (μm) of the Y-axis in the viewing area. The height difference in the area is displayed in color (shading). In FIG. 6, a portion indicated by a dark color (a portion indicated by red in the basic application) in a region where the value of the X axis is about 0 (μm) to 20 (μm) is a height from the reference plane. Indicates a relatively high film surface area of about 11.7 μm, and a portion indicated by a dark color in an area where the value of the X axis is about 70 (μm) to about 95 (μm) (Shown portion) shows a relatively low film surface area having a height from the reference plane of about 10.5 μm.
Operation 2. Fourth order was selected as the approximate surface shape in the surface correction, and the surface correction was performed.
Operation 3. The cutoff value was set to 1 μm in the undulation analysis, the target was extended to the boundary processing, “interpolate the edge portion” was selected from the set mode, and the undulation image was output.
As a result of each operation up to this point, a screen displayed on the monitor of the apparatus by the analysis software VS-Viewer in Example 1 is shown in FIG. 7A. FIG. 7A shows a swell image output as a result of each operation up to the above-described operation 3, that is, a swell image in which the reference plane of the height difference is changed from FIG.
In the waviness image of FIG. 7A, the film surface area that is lower than the reference plane by about 0.009 μm in the measurement area has an X-axis value of about 55 (μm) to 75 (μm) and a Y-axis value of 25. (Μm) to 35 (μm) in the range of dark colors (shown in blue in the basic application), and the film surface area higher than the reference plane in the measurement area by about 0.005 μm is other dark areas. It is shown in color (it was shown in red in the basic application). The timing at which the swell image of FIG. 7A is actually displayed on the monitor is immediately after the operation 4 described below.
Operation 4. Angle / normal analysis was performed on the obtained undulating image under the following conditions. The area ratio described in the output histogram was defined as the ratio of the area occupied by the inclination angle of 0.3 degrees or more.
Analysis: Angle Direction: XY
Area threshold: 0.3 deg
Output: Histogram The result of each operation up to operation 4 and the undulation image of Example 1 showing the result of angle / normal analysis displayed on the monitor of the apparatus by the analysis software VS-Viewer are shown in FIG. 7B. Was. FIG. 7B shows the relationship between the inclination angle and the frequency of each pixel obtained by the above analysis. The horizontal axis represents the inclination angle (angle: deg), and the vertical axis represents each inclination angle. Shows the frequency of pixels having As shown in FIG. 7 (B), as a result of the angle / normal analysis on Example 1, the slope region having a slope angle of not less than 0.3000 degrees (deg) displayed as the threshold value is the entire film area to be measured. The value of the slope rate (shown as the area rate in FIG. 7B), which is the ratio shown in FIG.

割 合 The measuring method of the ratio (inclined rate) of the inclined area having an inclined angle different from the above-mentioned 0.3 degree to the total surface area of the surface to be measured was in accordance with the above-described method. That is, in the method of measuring the inclination rate of the inclined regions having the inclination angles of 0.15 degrees (deg, degree) and 0.2 degrees, respectively, instead of 0.3 degrees as the threshold value of the inclination angle, 0. The method is the same as the above-described measurement method except that 15 degrees and 0.2 degrees are used, respectively.

<Method of measuring Sa on film and roll replica surface>
The arithmetic average height (Sa) in the range of 70 μm × 70 μm was measured using a white interference microscope (VS-1550, Hitachi High-Tech Science Co., Ltd.) based on ISO25178.

<Measurement of dYI value>
The dYI value based on ASTM E313-05 was measured as follows.
A 15% by weight dichloromethane solution of a polycarbonate resin was placed in a glass cell, and light from a D65 light source was transmitted through a 50 mm dichloromethane solution layer and received by a light receiving portion. The transmittance calculated at this time was defined as a dYI value. For this measurement, a spectral colorimeter SD-6000 manufactured by Nippon Denshoku Industries Co., Ltd. was used. This measurement was performed after a reference measurement was performed by placing only the solvent in a glass cell having a length of 50 mm, and the dYI value was corrected according to the type of the cell and the solvent.

<Measurement of brightness>
The brightness of the film surface when the LED light was guided from the end to a sample film (thickness 0.47 mm) cut into a 12 cm square was measured with a luminance meter (LS) from an angle of about 20 degrees with respect to the film plane. -110 Konica Minolta). The light guide direction is the MD direction (the direction in which the resin flows when the resin film is formed) and the TD direction (the direction perpendicular to the MD direction). The maximum value was measured as the luminance value (Cd / m ² ).

<Whiteness of film surface>
The whiteness of the film surface when the LED light was guided from the end to the sample film cut into a 12 cm square was evaluated according to the following criteria.
Particularly good: Almost no whiteness on the surface.
Good: The surface is slightly whitish.
Slightly poor: Whitening of the surface is observed. Bad: Whitening of the surface is strongly observed.

[Example 1]
A resin film was manufactured as follows.
Pellets of aromatic polycarbonate resin (Iupilon (registered trademark) HL-3000, manufactured by Mitsubishi Engineering-Plastics Corporation) (PC resin having a bisphenol A skeleton and a weight average molecular weight of about 19,000) are placed in a hot air dryer. After drying, the pellets were melted with a single screw extruder having a T-die lip and having a screw diameter of 90 mm and extruded to form a resin film. In the extrusion step, a roll A having the shape shown in the following Table 1 was used, and the roll A and the rolls BD used in other examples or comparative examples were plated with chromium (Cr) on the surface. , And their surface shapes are almost equal to the roll replica shapes shown in Table 1, respectively.
In the single screw extruder, the pellets were melted under an atmosphere of nitrogen gas. By such a nitrogen purge, the dYI value of the produced resin film was suppressed to a low value.

[Examples 2 to 12]
As shown in Table 1, as the polycarbonate resin, the above-mentioned Iupilon (Iupilon (registered trademark)) HL-3000, Iupilon (Iupilon (registered trademark)) S-3000 (manufactured by Mitsubishi Engineering-Plastics Corporation) (viscosity having a bisphenol A skeleton) PC resin having an average molecular weight of about 39,000) or Iupilon (registered trademark) E-2000 (manufactured by Mitsubishi Engineering-Plastics Corporation) (PC resin having a bisphenol A skeleton and having a weight average molecular weight of about 36,000) ) Was adopted. Then, a resin film was formed in the same manner as in Example 1 except that at least one of the type of the polycarbonate resin, the type of the roll used in the melt extrusion step, and the presence or absence of nitrogen purge was different from that of Example 1.

[Comparative Examples 1 to 4]
In Comparative Examples 1 to 4, as shown in Table 1, the type of roll used in the melt extrusion process was different from each Example, and Comparative Example 2 and Comparative Examples 2 and 4 were different from Example 1 in that no nitrogen purge was employed. Otherwise, a resin film was formed in the same manner as in Example 1.

With respect to the resin film thus manufactured, the surface shape was measured to calculate predetermined parameter values, and the properties of the resin film were measured. These results are summarized in Table 1.
In addition, when FIG. 4 showing the surface of the resin film of Example 3 and FIG. 5 showing the surface of the resin film of Comparative Example 1 in a state where light is guided from the end (side surface) are compared, in Example 3, Indicates that almost no light was emitted from the surface and the surface was dark (FIG. 4), whereas in Comparative Example 1 in which the film surface was generally bright, light was emitted from the surface (FIG. 4). 5).

10 Resin film 12 Inclined area 32 Second roll (metal roll)

Claims (14)

(4) A resin film in which the ratio of the area occupied by the inclined region having an inclination angle of 0.3 ° or more on the surface is 10% or less. The resin film according to claim 1, wherein the ratio of the area occupied by the inclined region on the surface is 0.01% or more. 樹脂 The resin film according to claim 1, wherein a ratio of an area occupied by an inclined region having an inclination angle of 0.2 ° or more on the surface is 30% or less. (4) The resin film according to any one of (1) to (3), wherein the ratio of the area occupied by the inclined region having an inclination angle of 0.15 degrees or more on the surface is 45% or less. The resin film according to any one of claims 1 to 4, wherein a value of the surface roughness Sa based on ISO 25178 on the surface is 5.0 nm or less. The resin film according to claim 5, wherein the value of the surface roughness Sa on the surface is 1.0 nm or more. The resin film according to any one of claims 1 to 6, wherein a dYI value based on ASTM E313-05 is 0.8 or less. The resin film according to any one of claims 1 to 7, wherein the resin film is manufactured by a melt extrusion method. The resin film according to claim 8, further comprising a melt extrusion step of melt-extruding the resin material of the resin film in the melt extrusion method. Polycarbonate (PC) resin, acrylic resin, polyethylene terephthalate (PET), triacetyl cellulose (TAC), polyethylene naphthalate (PEN), polyimide (PI), cycloolefin polymer (COP), cycloolefin copolymer (COC), norbornene-containing The resin film according to any one of claims 1 to 9, comprising at least one of a resin, polyether sulfone, cellophane, and aromatic polyamide. The resin film according to claim 10, wherein the acrylic resin contains polymethyl methacrylate (PMMA). A light guide plate having a surface corresponding to the surface of the resin film according to any one of claims 1 to 11 as a light emitting surface. The method for producing a resin film according to any one of claims 1 to 11, further comprising a melt extrusion step of melt-extruding the resin material of the resin film. The roll according to claim 13, wherein a roll having an uneven shape formed on the surface such that a ratio of an area occupied by an inclined region having an inclination angle of 0.3 ° or more is 5% or less is used in the melt extrusion step. A method for manufacturing a resin film.

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