Light-shielding film and lens unit

Abstract

The present invention provides a light-shielding film with excellent front-to-back discrimination properties and a lens unit equipped therewith. [Solution] A light-shielding film 1 comprising a light-shielding film substrate 2, a first anti-gloss layer 3, and a second anti-gloss layer 4, wherein the first anti-gloss layer is disposed on the outermost surface of the front side of the light-shielding film, the second anti-gloss layer is disposed on the outermost surface of the back side of the light-shielding film, the optical density of the first anti-gloss layer and the second anti-gloss layer is less than the optical density of the film substrate, the gloss of at least one of the first anti-gloss layer and the second anti-gloss layer at an incident angle of 60 degrees is greater than 0% and 1.0% or less, the absolute value of the difference in gloss between the first anti-gloss layer and the second anti-gloss layer is 1% or less, and the lightness index (L) of the first anti-gloss layer and the second anti-gloss layer * The light-shielding film is one in which the absolute value of the difference between the two values ​​is 2 or more, and the optical density value of the light-shielding film is 4 or more.

Description

[Technical Field]

[0001] This disclosure relates to a light-shielding film and a lens unit. [Background technology]

[0002] Lens units, which are installed in optical devices such as smartphones and digital video cameras, are generally composed of a combination of multiple lenses. Light-shielding members are used as components to block unwanted light, prevent halation, lens flare, ghosting, etc., and improve the image quality of captured images, and as shutters, aperture members, or gap adjustment members placed between multiple lenses in optical components. For example, Patent Document 1 describes a light-shielding film as a light-shielding member that can reduce thickness while maintaining good light-shielding properties. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2023-58702 [Overview of the Initiative] [Problems that the invention aims to solve]

[0004] In recent years, the demand for even higher functionality and miniaturization of camera modules has led to the incorporation of smaller lenses and light-shielding components into lens units. When incorporating light-shielding components into camera modules, poor distinguishing between the front and back sides of the component can lead to manufacturing errors such as incorrect installation and reduced productivity. In particular, with light-shielding films that have a black light-shielding layer, distinguishing between the front and back sides of the film becomes extremely difficult as the size decreases. To assist in distinguishing between the front and back sides of light-shielding components, methods such as applying minute markings as Merck marks are sometimes employed.

[0005] The present disclosure aims to provide a light-shielding film with excellent front-back discriminability and a lens unit including the same.

Means for Solving the Problems

[0006] The present disclosure includes the following aspects. A light-shielding film including a film substrate having light-shielding properties, a first anti-glare layer, and a second anti-glare layer, wherein the first anti-glare layer is disposed on the outermost surface on the front side of the light-shielding film, the second anti-glare layer is disposed on the outermost surface on the back side of the light-shielding film, the optical densities of the first anti-glare layer and the second anti-glare layer are smaller than the optical density of the film substrate, the glossiness of at least one of the first anti-glare layer and the second anti-glare layer at an incident angle of 60 degrees is greater than 0% and 1.0% or less, the absolute value of the difference in glossiness between the first anti-glare layer and the second anti-glare layer is 1% or less, the absolute value of the difference in lightness index (L * ) between the first anti-glare layer and the second anti-glare layer is 2 or more, and the value of the optical density of the light-shielding film is 4 or more.

Effects of the Invention

[0007] According to the present disclosure, it is possible to provide a light-shielding film with excellent front-back discriminability and a lens unit including the same.

Brief Description of the Drawings

[0008] [Figure 1] It is a cross-sectional view of one embodiment of the light-shielding film according to the first embodiment. [Figure 2] It is a cross-sectional view of another embodiment of the light-shielding film according to the first embodiment. [Figure 3] It is a partially enlarged view of the front side of the light-shielding film of one embodiment. [Figure 4] It is a cross-sectional view of the lens unit according to the second embodiment. [Embodiments for Carrying Out the Invention]

[0009] Hereinafter, one embodiment of the present disclosure will be described in detail. However, the scope of the present disclosure is not limited to the one embodiment described here, and various modifications can be made without departing from the spirit of the present disclosure. Each aspect disclosed in this specification can be combined with any other features disclosed in this specification. When a plurality of upper limit values and lower limit values are described for a specific parameter, any upper limit value and lower limit value can be combined to form a suitable numerical range. The lower limit value and / or upper limit value of the numerical range described in the present disclosure are numerical values within that numerical range and may be replaced with the numerical values shown in the examples. The expression "X to Y" indicating a numerical range means "X or more and Y or less". When a specific description given for one embodiment also applies to other embodiments, the description may be omitted in other embodiments.

[0010] [Light-Shielding Film] The first embodiment of the present disclosure relates to a light-shielding film. The light-shielding film according to the first embodiment is a light-shielding film including a film substrate having light-shielding properties, a first anti-glare layer, and a second anti-glare layer, wherein the first anti-glare layer is disposed on the outermost surface on the front side of the light-shielding film, the second anti-glare layer is disposed on the outermost surface on the back side of the light-shielding film, the optical densities of the first anti-glare layer and the second anti-glare layer are smaller than the optical density of the film substrate, the glossiness of at least one of the first anti-glare layer and the second anti-glare layer at an incident angle of 60 degrees is greater than 0% and 1.0% or less, the absolute value of the difference in glossiness between the first anti-glare layer and the second anti-glare layer is 1% or less, the absolute value of the difference in lightness index (L * ) between the first anti-glare layer and the second anti-glare layer is 2 or more, The optical density value of the light-shielding film is 4 or higher.

[0011] As mentioned above, in light-blocking films, especially those with a black light-blocking layer, it became extremely difficult to distinguish the front and back sides of the film as the size decreased. Conventionally, in light-blocking films in which layers with anti-gloss and light-blocking properties are provided on both sides of a transparent film substrate, it has been considered to enable visual identification of the front and back sides by creating a difference in gloss between the front and back sides of the light-blocking film. In this method, however, it was theoretically impossible to keep the gloss level low on both sides.

[0012] The inventors have diligently conducted research and, by adjusting the layer structure of the light-shielding film and the parameters of each layer, have achieved a difference in brightness index (L) between the front and back sides. * By creating a difference in the front and back sides, we have gained the insight that it is possible to obtain a light-shielding film that improves the ability to distinguish between the front and back sides while keeping the difference in gloss between the front and back sides small, thereby keeping the gloss of both sides small, and have completed this disclosure.

[0013] By using the light-shielding film according to the first embodiment, a light-shielding film with excellent front-to-back discrimination properties and a lens unit equipped therewith can be obtained. Excellent front-to-back discrimination properties improve handling in the camera module manufacturing process, suppress the occurrence of assembly defects, and improve productivity and cost-effectiveness. Furthermore, the light-shielding film according to this embodiment has a lightness index (L) that does not increase gloss. * By changing only the gloss level, it possesses the unique characteristic of being able to block unwanted light.

[0014] Figure 1 is a cross-sectional view of one embodiment of the light-shielding film 1 according to the first embodiment. The light-shielding film 1 comprises a light-shielding film substrate 2, a first anti-gloss layer 3, and a second anti-gloss layer 4. The first anti-gloss layer 3 is located on the outermost surface of the front side of the light-shielding film 1. The second anti-gloss layer 4 is located on the outermost surface of the back side of the light-shielding film 1. The optical density of the first anti-gloss layer 3 and the second anti-gloss layer 4 is lower than the optical density of the film substrate 2. In other words, the first anti-gloss layer 3 and the second anti-gloss layer 4 are more transparent than the film substrate 2. Because the first anti-gloss layer 3 and the second anti-gloss layer 4 are more transparent than the light-shielding film substrate 2, reflected light can be effectively suppressed. As a result, a light-shielding film is obtained that has excellent light-shielding properties while keeping gloss and brightness low.

[0015] Figure 2 is a cross-sectional view of another embodiment of the light-shielding film according to the first embodiment. The light-shielding film 10 shown in Figure 2 comprises a light-shielding film substrate 20, a first anti-gloss layer 3, and a second anti-gloss layer 4. As shown in Figure 2, the light-shielding film substrate 20 of the light-shielding film 10 comprises a film member 21 and light-shielding layers 22 and 23 arranged on top of the film member 21, and as a whole, has light-shielding properties similar to those of the light-shielding film substrate 2. That is, in one embodiment, the light-shielding film substrate 20 has a plurality of layers, preferably three layers. The film member 21 does not have to have light-shielding properties. The light-shielding layers 22 and 23 have higher light-shielding properties than the film member 21. The film member 21 may be thinner or thicker than the light-shielding layers 22 and 23. The light-shielding layers 22 and 23 may each consist of two or more layers.

[0016] In the light-shielding film 10, the first anti-gloss layer 3 is placed on top of the light-shielding layer 22 provided on the front side of the film member 21, and the second anti-gloss layer 4 is placed on top of the light-shielding layer 23 provided on the back side of the film member 21. In other words, the first anti-gloss layer 3 is placed on the outermost surface of the front side of the light-shielding film 10, and the second anti-gloss layer 4 is placed on the outermost surface of the back side of the light-shielding film 10. The light-shielding film 10 having the above configuration can achieve the same effect as the light-shielding film 1. Furthermore, the film member 21 and the light-shielding layers 22 and 23 can be functionally separated. This improves the design flexibility of the light-shielding film 10.

[0017] The optical density of the light-shielding film according to the first embodiment is 4 or higher. A light-shielding film with an optical density of 4 or higher exhibits excellent light-shielding properties. In this specification, "optical density" refers to the optical density (OD value), which is a logarithmic representation of the degree of absorption. It is calculated by using an optical densitometer to irradiate a sample with a perpendicular transmitted light beam and expressing the ratio of the value to the value when the sample is absent as a logarithmic value. In one embodiment, the optical density values ​​of the light-shielding films 1 and 10 are preferably 4.5 or higher, more preferably 5 or higher, even more preferably 5.5 or higher, and particularly preferably 6 or higher, from the viewpoint of excellent light-shielding performance. There is no upper limit, and the higher the value, the better the light-shielding performance.

[0018] In one embodiment, the total thickness of the light-shielding films 1 and 10 is preferably 50 μm or less, more preferably 40 μm or less, even more preferably 30 μm or less, and particularly preferably 25 μm or less. In another embodiment, the total thickness of the light-shielding films 1 and 10 is preferably 5 to 50 μm, more preferably 5 to 40 μm, even more preferably 10 to 30 μm, and particularly preferably 10 to 25 μm, from the viewpoint of easily maintaining excellent light-shielding properties even in small-sized lens units.

[0019] In this specification, "thickness" refers to the arithmetic mean of values ​​measured at any 10 locations using a film thickness measuring instrument. For example, the "Lightmatic VL-50-B" manufactured by Mitutoyo Corporation can be used as a film thickness measuring instrument.

[0020] [Light-shielding film substrate] The light-shielding film substrates 2 and 20 support various layers, such as the first anti-gloss layer 3 and the second anti-gloss layer 4, which are placed on top of the light-shielding film substrate 2, and also impart light-shielding properties to the light-shielding films 1 and 10. "Having light-blocking properties" literally means having the effect of blocking light. Since the base material has light-blocking properties, it is not necessary to set the light-blocking properties of the first and second anti-gloss layers, which will be described later, to be high. This increases the design flexibility of the first and second anti-gloss layers, and the brightness index (L) * By adjusting the difference between these two factors, unwanted light can be blocked without increasing gloss. As a result, it is easier to obtain a light-blocking film that has excellent front-to-back distinction and suppresses unwanted reflected light.

[0021] In one embodiment, the material of the light-shielding film substrate 2 and film member 21 is preferably a resin film. In one embodiment, from the viewpoint of dimensional stability, mechanical strength, and weight reduction, the material of the light-shielding film substrate 2 and film member 21 is preferably a synthetic resin film. Examples of synthetic resin films include polyester film, ABS (acrylonitrile-butadiene-styrene) film, polyimide film, polyamide film, polyamide-imide film, polystyrene film, polycarbonate film, acrylic film, polyolefin film, cellulose film, polysulfone film, polyphenylene sulfide film, polyethersulfone film, and polyetheretherketone film, and it is more preferable that the film contains one or more selected from these.

[0022] In one embodiment, the light-shielding film substrates 2 and 20 preferably contain a black component. In one embodiment, the light-shielding film substrate 20 having light-shielding layers 22 and 23 preferably contains a black component as a whole, since the light-shielding layers 22 and 23 contain a black component. The film member 21 may or may not contain a black component. By containing a black component, the light-shielding film substrates 2 and 20 are colored black and given light-shielding properties.

[0023] Examples of black components include carbon black, vine black, peach black, bone char, carbon nanotubes, silver oxide, zinc oxide, magnetite-type triiron tetroxide, copper-chromium composite oxide, copper-chromium-zinc composite oxide, black glass, aniline black, lamp black, graphite, Mars black, iron-titanium brown spinel, cobalt black, manganese black, zinc sulfide, manganese ferrite black, iron-cobalt chromite black, manganese iron oxide, molybdenum disulfide, and titanium dioxide black. It is preferable to include carbon black because it is readily available. Various types of carbon black are known, such as oil furnace black, channel black, gas furnace black, acetylene black, thermal black, and Ketjen black, which are produced by various known methods, but the type is not particularly limited.

[0024] In one embodiment, the amount of black component added is preferably greater than 0 parts by mass and 50 parts by mass or less in the total amount (100 parts by mass) of the light-shielding film substrate 2, or in the total amount (100 parts by mass) of the light-shielding film substrate 20 having light-shielding layers 22, 23, more preferably greater than 0 parts by mass and 40 parts by mass or less, and even more preferably greater than 5 parts by mass and 30 parts by mass or less.

[0025] In one embodiment, the light-shielding layers 22 and 23 of the light-shielding film substrate 20 preferably contain a binder resin and a black component. A wide range of resins can be selected as the binder resin, such as thermoplastic resins, thermosetting resins, and photocurable resins. For thermoplastic resins, thermosetting resins, and photocurable resins, the same resins as those exemplified as the binder resin 30 in the sections on the first anti-gloss layer and the second anti-gloss layer described later are exemplified, and it is preferable to include one or more selected from among them. Among these, thermosetting resins are preferred.

[0026] In one embodiment, the thickness of the light-shielding film substrates 2 and 20 is preferably 2 μm or more and 30 μm or less, more preferably 2 μm or more and 20 μm or less, even more preferably 2 μm or more and 15 μm or less, and particularly preferably a value in the range of 2 μm or more and less than 10 μm.

[0027] In one embodiment, the light-shielding film substrate 20 having light-shielding layers 22 and 23 preferably has a film member 21 with a thickness of 2 to 30 μm (preferably 4 to 12 μm), a light-shielding layer 22 with a thickness of 0.5 to 10 μm (preferably 1 to 5 μm), and a light-shielding layer 23 with a thickness of 0.5 to 10 μm (preferably 1 to 5 μm).

[0028] [First anti-gloss layer, second anti-gloss layer] The light-shielding films 1 and 10 according to the first embodiment have a first anti-gloss layer 3 and a second anti-gloss layer 4 on the outermost surfaces of the front and back surfaces, respectively. In the light-shielding films 1 and 10, the glossiness of at least one of the first anti-gloss layer 3 and the second anti-gloss layer 4 at an incident angle of 60 degrees is greater than 0% and 1.0% or less, and the absolute value of the difference in glossiness (glossiness at an incident angle of 60 degrees) between the first anti-gloss layer 3 and the second anti-gloss layer 4 is 1% or less.

[0029] In this specification, "glossiness at an incident angle of 60 degrees" refers to specular glossiness based on the measurement method in accordance with JIS Z 8741:1997, and is a value measured using a gloss meter. The glossiness of at least one of the first anti-gloss layer 3 and the second anti-gloss layer 4 at an incident angle of 60 degrees is greater than 0% and 1.0% or less, and the absolute value of the difference in glossiness between the first anti-gloss layer 3 and the second anti-gloss layer 4 is 1% or less, thereby suppressing unwanted reflected light from the light-shielding films 1 and 10 described later, while providing excellent front-to-back discrimination. The absolute value of the difference in glossiness between the first anti-gloss layer 3 and the second anti-gloss layer 4 only needs to be 1% or less; in other words, either the glossiness of the first anti-gloss layer 3 or the glossiness of the second anti-gloss layer 4 may be greater.

[0030] In one embodiment, it is preferable that the glossiness of both the first anti-gloss layer 3 and the second anti-gloss layer 4 at an incident angle of 60 degrees is greater than 0% and 1.0% or less. By having the glossiness of both the first anti-gloss layer 3 and the second anti-gloss layer 4 at an incident angle of 60 degrees greater than 0% and 1.0% or less, the unwanted reflected light of the light-shielding films 1 and 10 is further suppressed while maintaining excellent front-to-back discrimination.

[0031] In one embodiment, the gloss of at least one of the first anti-gloss layer 3 and the second anti-gloss layer 4 at an incident angle of 60 degrees (preferably the gloss of the first anti-gloss layer 3 and the second anti-gloss layer 4 at an incident angle of 60 degrees) is greater than 0% and 1.0% or less, preferably greater than 0% and 0.8% or less, more preferably greater than 0% and 0.5% or less, even more preferably greater than 0% and 0.5% or less, and may be greater than 0% and 0.3% or less.

[0032] In one embodiment, the absolute value of the difference in gloss between the first anti-gloss layer 3 and the second anti-gloss layer 4 is 1% or less, preferably 0% or more and 1% or less, more preferably 0% or more and 0.8% or less, may be greater than 0% and 0.8% or less, may be greater than 0% and 0.5% or less, or may be greater than 0% and 0.3% or less.

[0033] The gloss level at an incident angle of 60 degrees can be adjusted by creating surface irregularities. Methods for creating surface irregularities include adding fillers, post-processing such as sandblasting, and transferring the irregular shape. When adding fillers, for example, adjustments can be made by varying the amount, particle size, shape, and layer thickness of the filler.

[0034] In one embodiment, the lightness index (L) of the first anti-gloss layer 3 and the second anti-gloss layer 4 is * The absolute value of the difference between ) is 2 or greater, preferably 2.3 or greater, more preferably 2.5 or greater, and even more preferably 3 or greater. In this specification, "lightness index (L) *)」 means the lightness (L defined in JIS Z 8781-4 * ). Since the absolute value of the difference in the lightness index (L * ) between the first anti-glare layer 3 and the second anti-glare layer 4 is 2 or more, the lightness on the front and back of the light-shielding films 1 and 10 is clearly different, so the front-back discrimination is excellent. * ) is 2 or more, the lightness on the front and back of the light-shielding films 1 and 10 is clearly different, so the front-back discrimination is excellent. In this embodiment, it is sufficient that the absolute value of the difference in the lightness index (L * ) is 2 or more. That is, the lightness index (L*) of the first anti-glare layer 3 and the lightness index (L*) of the second anti-glare layer 4 may be either larger. The difference in hue between the first anti-glare layer 3 and the second anti-glare layer 4 is not limited. In one embodiment, the color difference ΔE*ab between the first anti-glare layer 3 and the second anti-glare layer 4 may be less than 0.4, or may be 0.3 or less. ΔE*ab means a value measured in accordance with JIS Z 8781-4. * ) is 2 or more, that is, the lightness index (L*) of the first anti-glare layer 3 and the lightness index (L*) of the second anti-glare layer 4 may be either larger. The difference in hue between the first anti-glare layer 3 and the second anti-glare layer 4 is not limited. In one embodiment, the color difference ΔE*ab between the first anti-glare layer 3 and the second anti-glare layer 4 may be less than 0.4, or may be 0.3 or less. ΔE*ab means a value measured in accordance with JIS Z 8781-4.

[0035] In one embodiment, it is preferable that the lightness index (L * ) of at least one surface of the first anti-glare layer and the second anti-glare layer is 25 or less. Since the lightness index (L * ) of at least one surface of the first anti-glare layer and the second anti-glare layer is 25 or less, light-shielding films 1 and 10 with a low lightness on the surface where the layer is located can be obtained. * ) is 25 or less, light-shielding films 1 and 10 with a low lightness on the surface where the layer is located can be obtained. * ) is 25 or less, light-shielding films 1 and 10 with a low lightness on the surface where the layer is located can be obtained. The lightness index (L * ) of at least one surface of the first anti-glare layer and the second anti-glare layer is 25 or less, preferably 1 to 25, may be 2 to 25, may be 5 to 25, or may be 10 to 20. * ) is 25 or less, preferably 1 to 25, may be 2 to 25, may be 5 to 25, or may be 10 to 20. In one embodiment, when the lightness index (L * ) of either surface of the first anti-glare layer and the second anti-glare layer is 25 or less, the lightness index (L * ) of the other surface may exceed 25. In another embodiment, the lightness index (L * ) of both surfaces of the first anti-glare layer and the second anti-glare layer may be 25 or less, or may be 20 or less. From the viewpoint of easily increasing the difference in the lightness index (L * ), the lightness index (L * ) of either surface of the first anti-glare layer and the second anti-glare layer is 25 or less, the lightness index (L * ) of the other surface may exceed 25. In another embodiment, the lightness index (L * ) of both surfaces of the first anti-glare layer and the second anti-glare layer may be 25 or less, or may be 20 or less. From the viewpoint of easily increasing the difference in the lightness index (L * ), the lightness index (L * [[ID=2​​​​* The brightness index (L) of the other surface is set to 25 or less (preferably 20 or less), and the brightness index (L) of the other surface is set to 25 or less. * It is preferable to set the value to more than 25 (preferably 20 or more).

[0036] Lightness index (L * The color intensity can be adjusted, particularly by changing the color of the outermost layer. Coloring it white increases the intensity, while coloring it black decreases it. Coloring can be done by adding dyes or pigments. By combining transparency, the underlying color can also be utilized. Multiple colors can also be combined.

[0037] In one embodiment, the first anti-gloss layer 3 and the second anti-gloss layer 4 preferably contain a binder resin and filler particles. From the viewpoint of easily forming irregularities across the entire surface, it is preferable that the filler particles are dispersed in the binder resin. By including a binder resin and filler particles in the first anti-gloss layer 3 and the second anti-gloss layer 4, irregularities are formed on the surfaces of the first anti-gloss layer 3 and the second anti-gloss layer 4, thereby providing the light-shielding films 1 and 10 with anti-glare properties that scatter incident light from the outside with the irregularities on the surfaces of the first anti-gloss layer 3 and the second anti-gloss layer 4.

[0038] In one embodiment, the amount of filler particles added is preferably 1 to 50 parts by mass, more preferably 2 to 45 parts by mass, even more preferably 5 to 40 parts by mass, and particularly preferably 10 to 40 parts by mass, in the total amount (100 parts by mass) of the first anti-gloss layer 3 and / or the total amount (100 parts by mass) of the second anti-gloss layer 4.

[0039] Brightness index (L) between the first anti-gloss layer 3 and the second anti-gloss layer 4 * From the viewpoint of easily increasing the absolute value of the difference between the two layers, it is preferable that the amounts of filler particles added to the first anti-gloss layer 3 and the second anti-gloss layer 4 are different. The more filler particles added, the higher the brightness index (L). *If the ) tends to become large, for example, the amount of filler particles added to the second anti-gloss layer 4 may be greater than the amount of filler particles added to the first anti-gloss layer 3.

[0040] In one embodiment, it is preferable that the first anti-gloss layer 3 and the second anti-gloss layer 4 further contain a coloring component (for example, a black component such as carbon black). The types of coloring components will be described later. In one embodiment, the amount of coloring component added to the first anti-gloss layer 3 and the second anti-gloss layer 4 is preferably greater than 0 parts by mass and 50 parts by mass or less, more preferably greater than 0 parts by mass and 45 parts by mass or less, even more preferably greater than 0 parts by mass and 40 parts by mass or less, and particularly preferably greater than 0 parts by mass and 30 parts by mass or less, in the total amount (100 parts by mass) of the first anti-gloss layer 3 and the total amount (100 parts by mass) of the second anti-gloss layer 4. If the coloring component is carbon black, it is preferably greater than 0 parts by mass and 20 parts by mass or less, more preferably greater than 0 parts by mass and 15 parts by mass or less, even more preferably greater than 0 parts by mass and 10 parts by mass or less, and particularly preferably greater than 0 parts by mass and 5 parts by mass or less. The type and amount of coloring components contained in the first anti-gloss layer 3 and the second anti-gloss layer 4 may be the same or different. From the viewpoint of reducing the absolute value of the difference in gloss between the first anti-gloss layer and the second anti-gloss layer at an incident angle of 60 degrees, it is preferable that the amount of coloring component contained in the first anti-gloss layer 3 and the amount of coloring component contained in the second anti-gloss layer 4 are the same.

[0041] Figure 3 is a partially enlarged view of the surface of the light-shielding films 1 and 10 according to one embodiment. The surface configuration of the light-shielding films 1 and 10 will be described below, but the back side of the light-shielding films 1 and 10 has a similar configuration if the first anti-gloss layer 3 is read as the second anti-gloss layer 4. The first anti-gloss layer 3 comprises a binder resin 30 and filler particles 31 dispersed in the binder resin 30, and may further contain a coloring component (e.g., carbon black) 32 dispersed in the binder resin 30. The surface irregularities of the first anti-gloss layer 3 are formed by the dispersion and arrangement of multiple filler particles 31 in the binder resin 30, and by the filler particles 31 protruding on the side opposite to the light-shielding film substrates 2, 20 of the first anti-gloss layer 3, thereby raising the surface of the binder resin 30. The filler particles 31 may be any inorganic particles capable of imparting anti-gloss properties, such as silica particles, alumina, aluminum silicate, clay, smectite, calcium carbonate, calcium sulfate, barium sulfate, titanium dioxide, synthetic zeolite, and other inorganic fillers, and it is preferable to include one or more selected from these. Of these, silica particles are more preferable due to their versatility and variety.

[0042] The average particle size of the filler particles 31 can be set as appropriate. In one embodiment, the average particle size of the filler particles 31 is preferably 0.1 μm or more and 10 μm or less, more preferably 0.2 μm or more and 8 μm or less, and even more preferably 0.3 μm or more and 6 μm or less. The average particle size may be the manufacturer's catalog value, or it may be the volume-based arithmetic mean particle diameter measured by laser diffraction / scattering particle size distribution analysis.

[0043] When the binder resin 30 contains a coloring component 32 dispersed in it, it is preferable that the coloring component 32 has higher light absorption than the filler particles 31. In the first anti-gloss layer 3, it is preferable that the coloring component 32 is dispersed around the filler particles 31. This prevents the reflected light from being emitted again from the surface of the anti-gloss layer 3 to the outside, even when light is incident on the first anti-gloss layer 3 from the outside, due to the fine particles of the coloring component 32. The multiple fine particles of the coloring component 32 may be arranged as separate primary particles, or they may be arranged as secondary particles aggregated in a certain number.

[0044] As the coloring component 32, known pigments and dyes can be used, but in one embodiment, from the viewpoint of easily improving light-shielding properties, it is preferable that it be a black component, and more preferably one or more selected from carbon black, lamp black, vine black, peach black, bone char, carbon nanotube, silver oxide, zinc oxide, magnetite-type triiron tetroxide, copper-chromium composite oxide, copper, chromium, zinc composite oxide, black glass, aniline black, lamp black, graphite, Mars black, iron titanium brown spinel, cobalt black, manganese black, zinc sulfide, manganese ferrite black, iron cobalt chromite black, manganese iron oxide, molybdenum disulfide, titanium dioxide black, barium titanate (BaTiO3). In one embodiment, the coloring component 32 is preferably carbon black from the viewpoint of being readily available and having excellent light-shielding properties.

[0045] The binder resin 30 includes at least one of a thermoplastic resin, a thermosetting resin, or a photocurable resin. Therefore, a wide range of resins can be selected as the binder resin 30.

[0046] As thermoplastic resins, one or more of the following can be used: polyolefins, styrene resins, acrylic resins, vinyl chloride resins, polyvinyl alcohol resins, polyacetals, polyesters, polycarbonates, polyamides, polyimides, polysulfone resins, polyphenylene ether resins, polyphenylene sulfide resins, fluororesins, cellulose derivatives, polyurethane resins, etc. Of these, cyclic polyolefins, polyalkylene arylates (polyethylene terephthalate (PET), polyethylene naphthalate (PEN), etc.), polymethyl methacrylate resins, bisphenol A type polycarbonate, and cellulose esters.

[0047] Examples of thermosetting resins include one or more from the following: acrylic resins, phenolic resins, melamine resins, urea resins, benzoguanamine resins, silicone resins, epoxy resins, unsaturated polyesters, vinyl ester resins, and urethane resins. Of these, epoxy resins, unsaturated polyesters, silicone resins, and urethane resins are preferred from the viewpoint of strength.

[0048] Examples of photocurable resins include one or more from among photocurable polyester, photocurable acrylic resin, photocurable epoxy (meth)acrylate, and photocurable urethane (meth)acrylate. Of these, photocurable acrylic resin and photocurable urethane (meth)acrylate are preferred from the viewpoint of strength. In this specification, "photocurable" means the property of polymerization and curing by light of a specific wavelength.

[0049] In one embodiment, the thickness of the first anti-gloss layer 3 and the second anti-gloss layer 4 is preferably 1 μm or more and 10 μm or less, more preferably 1 μm or more and 9 μm or less, even more preferably 2 μm or more and 8 μm or less, and particularly preferably 2 μm or more and 7 μm or less. The thicknesses of the first anti-gloss layer 3 and the second anti-gloss layer 4 may be the same or different. The method for measuring the thickness is as described above.

[0050] [Method for manufacturing light-blocking film] The manufacturing method for the light-shielding films 1 and 10 of the first embodiment includes a step (step B) of forming a first anti-gloss layer 3 and a second anti-gloss layer 4, which are arranged on the front and back surfaces of a light-shielding film substrate 2 and 20, respectively. The first anti-gloss layer 3 and the second anti-gloss layer 4 can be formed by applying a coating solution, prepared so that a layer of the desired components is obtained after curing and drying, to the front and back surfaces of the light-shielding film substrates 2 and 20, respectively, and then curing and drying them. If the coating solution contains a photocurable resin, the first anti-gloss layer 3 and the second anti-gloss layer 4 can be produced by photocuring the coating solution by light irradiation. If the coating solution contains a thermosetting resin, the first anti-gloss layer 3 and the second anti-gloss layer 4 can be produced by thermocuring.

[0051] In one embodiment, the method for manufacturing the light-shielding film 10 includes step A, which precedes step B, in which light-shielding layers 22 and 23 are formed on the front and back surfaces of the film member 21, respectively. The light-shielding layers 22 and 23 can be formed by applying a coating liquid, prepared so that a layer of the desired components is obtained after curing and drying, to the front and back surfaces of the film member 21, and then drying and curing it. If the coating liquid contains a photocurable resin, the light-shielding layers 22 and 23 can be produced by photocuring the coating liquid by light irradiation. If the coating liquid contains a thermosetting resin, the light-shielding layers 22 and 23 can be produced by thermocuring.

[0052] <Lens Unit> A second embodiment of this disclosure relates to a lens unit comprising a light-shielding film according to the first embodiment. Figure 4 is an exploded view of a lens unit 40 according to the second embodiment. As shown in Figure 4, the lens unit 40 comprises a plurality of light-shielding members F1 to F6, a plurality of optical members L1 to L6, and a housing (lens barrel) 41 that houses the plurality of light-shielding films and the plurality of optical members. The plurality of light-shielding members F1 to F6 are composed of light-shielding films 1 and 10 and are installed between adjacent optical members. The light-shielding members F1 to F6 and the plurality of optical members L1 to L6 are arranged on the same optical axis and stacked in a predetermined position within the housing (lens barrel) 41. The number of light-shielding members and optical members provided in the lens unit 40 is not limited. A camera module built into an electronic device such as a smartphone comprises a lens unit 40 and an image sensor, such as a CCD image sensor or a CMOS image sensor, which is arranged on the same optical axis as the lens unit 40 and captures an image of a subject through the lens unit 40. Multiple light-shielding members F1 to F6 prevent the occurrence of halation, lens flare, ghosting, etc., by removing unwanted incident and reflected light from the image sensor, thereby improving the image quality of the captured image. In addition, the multiple light-shielding members F1 to F6 also act as gap adjustment members between multiple optical members L1 to L6. The gap adjustment members can be set to a predetermined thickness to adjust the distance between the optical members L1 to L6.

[0053] A non-limiting list of exemplary embodiments and combinations of exemplary embodiments of this disclosure are disclosed below. [1] A light-shielding film comprising a light-shielding film substrate, a first anti-gloss layer, and a second anti-gloss layer, The first anti-gloss layer is placed on the outermost surface of the front side of the light-shielding film, The second anti-gloss layer is placed on the outermost surface of the back side of the light-shielding film, The optical density of the first anti-gloss layer and the second anti-gloss layer is less than the optical density of the film substrate. The glossiness of at least one of the first anti-gloss layer and the second anti-gloss layer at an incident angle of 60 degrees is greater than 0% and 1.0% or less (preferably greater than 0% and 1.0% or less, more preferably greater than 0% and 0.8% or less, even more preferably greater than 0% and 0.5% or less, and may be 0.1% or more and 0.3% or less), The absolute value of the difference in gloss between the first anti-gloss layer and the second anti-gloss layer is 1% or less (preferably 0% or more and 1% or less, more preferably 0% or more and 0.8% or less, it may be greater than 0% and 0.8% or less, it may be greater than 0% and 0.5% or less, and it may be greater than 0% and 0.3% or less), The lightness index (L) of the first anti-gloss layer and the second anti-gloss layer *The absolute value of the difference between ) is 2 or more (preferably 2.3 or more, more preferably 2.5 or more, and even more preferably 3 or more), A light-shielding film having an optical density value of 4 or more (preferably 4 to 10, more preferably 4.5 to 8, even more preferably 5 to 7, and particularly preferably 5.5 to 6.5). [2] The lightness index (L) of at least one of the first anti-gloss layer and the second anti-gloss layer * The light-shielding film according to [1], wherein the ratio is 25 or less (preferably 1 to 25, but may be 2 to 25, 5 to 25, or 10 to 20). [3] The light-shielding film according to [1] or [2], wherein the gloss of the first anti-gloss layer and the second anti-gloss layer at an incident angle of 60 degrees is greater than 0% and 1.0% or less. [4] The light-shielding film according to any one of [1] to [3], wherein the first anti-gloss layer and the second anti-gloss layer each comprise a binder resin and filler particles dispersed in the binder resin. [5] The light-shielding film according to [4], wherein the amount of filler particles added is 1 part by mass or more and 50 parts by mass or less with respect to 100 parts by mass of the total amount of the first anti-gloss layer and the total amount of the second anti-gloss layer. [6] The light-shielding film according to [5], wherein the filler particles dispersed in the binder resin are silica particles. [7] The light-shielding film according to any one of [1] to [6], further comprising the first anti-gloss layer and the second anti-gloss layer. [8] The light-shielding film according to any one of [1] to [7], wherein the thickness of the first anti-gloss layer and the second anti-gloss layer is 1 μm or more and 7 μm or less. [9] The light-shielding film according to any one of [1] to [8], wherein the light-shielding film substrate contains a coloring component.

[10] The light-shielding film according to [9], wherein the amount of coloring component added is greater than 0 parts by mass and 23 parts by mass or less, based on 100 parts by mass of the total amount of the light-shielding film substrate.

[11] The light-shielding film according to any one of [1] to

[10] , wherein the thickness of the light-shielding film substrate is 2 μm or more and 30 μm or less.

[12] A light-shielding film according to any one of [1] to

[11] , which is a shutter, aperture member, or gap adjustment member of an optical component, or is disposed between multiple lenses. A lens unit comprising a light-shielding film as described in any of

[13] [1] to

[12] . Each configuration and its combination in each embodiment is an example, and additions, omissions, substitutions, and other modifications can be made as appropriate without departing from the spirit of this disclosure. This disclosure is not limited by the embodiments. [Examples]

[0054] The present disclosure will be further illustrated by the following examples, but these examples will not limit the interpretation of the present disclosure.

[0055] [Example 1] (Manufacturing of light-shielding base films) A polyethylene terephthalate (PET) film with a thickness of 6 μm (manufactured by Toray Industries, Inc.) was prepared. Coating solution (1) was prepared by adding 100 parts by mass of urethane resin (manufactured by Koshin Chemical Co., Ltd., "KDC-01 Main Agent") as a binder resin to 150 parts by mass of carbon black dispersion (manufactured by Mikuni Pigment Co., Ltd., "MHI Black #273") and then adding 20 parts by mass of a curing agent (manufactured by Koshin Chemical Co., Ltd., "KDC-01 Curing Agent"). The coating solution (1) was applied to both sides of a polyethylene terephthalate film, and solvent-dried and heat-cured at 100°C to form a pair of light-shielding layers, each with a thickness of 1.5 μm after drying, thereby obtaining a light-shielding base film.

[0056] (Manufacturing of light-blocking film) Coating solution (2) was prepared by mixing 100 parts by mass of urethane resin (manufactured by Koshin Chemical Co., Ltd., "KDC-01 Main Agent") as a binder resin, 20 parts by mass of a curing agent (manufactured by Koshin Chemical Co., Ltd., "KDC-01 Curing Agent"), 12.5 parts by mass of silica particles (manufactured by Fuji Silicia Co., Ltd., "Silohobic 100", amorphous silica, average particle size 2.7 μm), and 25 parts by mass of carbon black dispersion (manufactured by Mikuni Pigment Co., Ltd., "MHI Black #273"). The coating liquid (2) was applied to the surface of a light-shielding substrate film, and solvent-dried and heat-cured at 100°C to form a first anti-gloss layer with a thickness of 3.5 μm after drying. Furthermore, a coating solution (3) was prepared in the same manner as coating solution (2), except that the silica particles were 16.5 parts by mass. The coating liquid (3) was applied to the back surface opposite the surface of the light-shielding substrate film, and solvent-dried and heat-cured at 100°C to form a second anti-gloss layer with a thickness of 3.5 μm after drying, thereby producing a light-shielding film.

[0057] [Example 2] A light-shielding film was prepared in the same manner as in Example 1, except that the amount of silica particles added to the second anti-gloss layer was 15 parts by mass. [Comparative Example 1] A light-shielding film was prepared in the same manner as in Example 1, except that the amount of silica particles added to the second anti-gloss layer was 13.5 parts by mass. [Comparative Example 2] A light-shielding film was prepared in the same manner as in Example 1, except that the amount of silica particles added to the second anti-gloss layer was 12.5 parts by mass.

[0058] [Measuring the brightness index] For each light-shielding film in the examples and comparative examples, the lightness index (L1) of the first anti-gloss layer was measured using the SCI method, with a spectrophotometer (Konica Minolta, Inc., "CM-600d") and a C light source as the illuminant for color measurement, in accordance with the measurement method in accordance with JIS Z 8722 and the measurement method based on microspectroscopy. * ) and the brightness index (L2) of the second anti-gloss layer * ) was measured. Furthermore, the absolute value of the difference in brightness index [[(L2* )-(L1 * )] or [(L1 * )-(L2 * We calculated the absolute value of ).

[0059] [Measurement of glossiness at an incident angle of 60 degrees (60-degree glossiness)] For each light-shielding film in the examples and comparative examples, the glossiness (60-degree gloss) (A) of the first anti-gloss layer at an incident angle of 60 degrees and the glossiness (60-degree gloss) (B) of the second anti-gloss layer at an incident angle of 60 degrees were measured using a gloss meter (Horiba, Ltd., "IG-320") in accordance with JIS K 7105. Furthermore, the absolute value of the difference in 60-degree glossiness [[(B)-(A)] or the absolute value of [(A)-(B)]] was determined.

[0060] [Measurement of optical density (OD value)] For each light-shielding film in the examples and comparative examples, the OD values ​​were measured in the wavelength range of 380 nm to 780 nm using a transmittance densitometer (Xrite Corporation, "Model 341C").

[0061] [Evaluation of front / back discrimination] For each light-shielding film in the examples and comparative examples, the ability to visually distinguish between the first surface on which the first anti-gloss layer is placed and the second surface on which the second anti-gloss layer is placed, opposite to the first surface, was evaluated. A rating of "1" was given if the front and back could be easily distinguished by visual inspection, a rating of "2" was given if the front and back could be distinguished by visual inspection, and a rating of "3" was given if it was difficult to distinguish the front and back by visual inspection. The results of each of the above measurements and evaluations are shown in Table 1.

[0062] [Table 1]

[0063] As shown in Table 1, the light-shielding films of the examples received front-to-back discrimination ratings of "1" and "2," indicating superior front-to-back discrimination. On the other hand, the light-shielding films of the comparative examples received front-to-back discrimination ratings of "3," indicating inferior front-to-back discrimination. The light-shielding film of the example has a lightness index (L2) of the second anti-gloss layer. * Even when the ) increased further, the increase in the 60-degree gloss of the second anti-gloss layer was suppressed, and it had the unique characteristic of having a small absolute value for the difference in 60-degree gloss between the front and back surfaces. [Industrial applicability]

[0064] The light-shielding film of this embodiment has excellent front-to-back distinguishability, which improves handling in the camera module manufacturing site, suppresses the occurrence of assembly defects, improves productivity and cost-effectiveness, and has industrial applicability. [Explanation of symbols]

[0065] F1~F6 Light-shielding material L1~L6 Optical components 1. 10 Light-blocking film 2.20 Light-shielding film substrate 3. First anti-gloss layer 4. Second anti-gloss layer 21 Film component 22, 23 Light blocking layer 30 Binder resin 31 Filler particles 32 Coloring ingredients 40 Lens Units 41. Enclosure (lens barrel)

Claims

1. A light-shielding film comprising a light-shielding film substrate, a first anti-gloss layer, and a second anti-gloss layer, The first anti-gloss layer is placed on the outermost surface of the front side of the light-shielding film. The second anti-gloss layer is placed on the outermost surface of the back side of the light-shielding film. The optical density of the first anti-gloss layer and the second anti-gloss layer is smaller than the optical density of the film substrate. The glossiness of at least one of the first anti-gloss layer and the second anti-gloss layer at an incident angle of 60 degrees is greater than 0% and 1.0% or less. The absolute value of the difference in gloss between the first anti-gloss layer and the second anti-gloss layer is 1% or less. The lightness index (L) of the first anti-gloss layer and the second anti-gloss layer ＊ The absolute value of the difference between ) is 2 or more, A light-shielding film having an optical density value of 4 or more.

2. The lightness index (L) of at least one of the first anti-gloss layer and the second anti-gloss layer ＊ The light-shielding film according to claim 1, wherein the value of ) is 25 or less.

3. The light-shielding film according to claim 1 or 2, wherein the gloss of the first anti-gloss layer and the second anti-gloss layer at an incident angle of 60 degrees is greater than 0% and 1.0% or less.

4. The light-shielding film according to claim 1 or 2, wherein the first anti-gloss layer and the second anti-gloss layer each comprise a binder resin and filler particles.

5. The light-shielding film according to claim 4, wherein the amount of filler particles added is 1 part by mass or more and 50 parts by mass or less, with respect to 100 parts by mass of the total amount of the first anti-gloss layer and the total amount of the second anti-gloss layer.

6. The light-shielding film according to claim 5, wherein the filler particles are silica particles.

7. The light-shielding film according to claim 1 or 2, wherein the first anti-gloss layer and the second anti-gloss layer further contain a coloring component.

8. The light-shielding film according to claim 1 or 2, wherein the thickness of the first anti-gloss layer and the second anti-gloss layer is 1 μm or more and 10 μm or less.

9. The light-shielding film according to claim 1 or 2, wherein the light-shielding film substrate contains a black component.

10. The light-shielding film according to claim 9, wherein the amount of coloring component added is greater than 0 parts by mass and 50 parts by mass or less, based on 100 parts by mass of the total amount of the light-shielding film substrate.

11. The light-shielding film according to claim 1 or 2, wherein the thickness of the light-shielding film substrate is 2 μm or more and 30 μm or less.

12. The light-shielding film according to claim 1 or 2, which is a shutter, aperture member, or gap adjustment member disposed between multiple lenses of an optical component.

13. A lens unit comprising the light-shielding film described in claim 1 or 2.

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