Light-shielding film and lens unit
A light-shielding film with controlled gloss and brightness differences between its layers addresses the challenge of distinguishing front and back sides in miniaturized lens units, enhancing handling and reducing defects in the manufacturing process.
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- DAICEL CORP
- Filing Date
- 2025-11-27
- Publication Date
- 2026-06-04
AI Technical Summary
The challenge of distinguishing between the front and back sides of light-shielding components in miniaturized lens units, particularly those with black light-shielding layers, leads to manufacturing errors and reduced productivity due to incorrect installation.
A light-shielding film structure with a first and second anti-gloss layer on the outermost surfaces, where the optical density of these layers is lower than the film substrate, and the gloss difference and brightness index difference between the layers are carefully controlled to facilitate easy front-to-back discrimination.
The solution enhances the ability to distinguish between the front and back sides of the film, reducing assembly defects and improving productivity while maintaining excellent light-shielding properties.
Smart Images
Figure JP2025041299_04062026_PF_FP_ABST
Abstract
Description
Light-shielding film and lens unit
[0001] This disclosure relates to a light-shielding film and a lens unit.
[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.
[0003] Japanese Patent Publication No. 2023-58702
[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 object of this disclosure is to provide a light-shielding film with excellent front-to-back discrimination properties, and a lens unit equipped therewith.
[0006] This disclosure includes the following embodiments: A light-shielding film comprising a light-shielding film substrate, a first anti-gloss layer, and a second anti-gloss layer, 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 is ＊ A light-shielding film in which the absolute value of the difference between ) is 2 or more, and the optical density value of the light-shielding film is 4 or more.
[0007] According to this disclosure, it is possible to provide a light-shielding film with excellent front-to-back discrimination properties, and a lens unit equipped therewith.
[0008] This is a cross-sectional view of one embodiment of the light-shielding film according to the first embodiment. This is a cross-sectional view of another embodiment of the light-shielding film according to the first embodiment. This is a partially enlarged view of the surface side of the light-shielding film according to one embodiment. This is a cross-sectional view of the lens unit according to the second embodiment.
[0009] One embodiment of the present disclosure will be described in detail below, but the scope of the present disclosure is not limited to the embodiment described herein, and various modifications can be made without departing from the spirit of the present disclosure. Each embodiment disclosed herein can be combined with any other features disclosed herein. If multiple upper and lower limits are given for a particular parameter, any combination of these upper and lower limits can be used to create a suitable numerical range. The lower and / or upper limits of the numerical ranges described herein may be replaced with numerical values within that range, as shown in the examples. The expression "X to Y" indicating a numerical range means "X or greater and Y or less". If a particular description given for one embodiment also applies to other embodiments, that description may be omitted in the other embodiments.
[0010] <Light-shielding film> The first embodiment of this disclosure relates to a light-shielding film. The light-shielding film according to the first embodiment is a light-shielding film comprising a light-shielding film substrate, a first anti-gloss layer, and a second anti-gloss layer, 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 brightness index (L) of the first anti-gloss layer and the second anti-gloss layer ＊ 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.
[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 these factors, 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 that, it has the unique characteristic of being able to block unwanted light by suppressing glossiness.
[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. That is, 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 same effect as the light-shielding film 1 can be obtained with the light-shielding film 10 having the above configuration. In addition, 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 value of the light-shielding film according to the first embodiment is 4 or higher. A light-shielding film with an optical density value of 4 or higher exhibits excellent light-shielding properties. In this specification, "optical density" refers to the value obtained by using an optical densitometer to irradiate a sample with a perpendicular transmitted light beam and expressing the ratio to the state without the sample on a logarithmic scale. In one embodiment, the optical density value of the light-shielding films 1 and 10 is 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 properties. There is no particular upper limit; the higher the value, the better the light-shielding properties.
[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 one 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" is defined as 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-blocking film substrate] The light-blocking 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-blocking film substrate 2, and also impart light-blocking properties to the light-blocking films 1 and 10. "Having light-blocking properties" literally means having the effect of blocking light. Since the substrate has light-blocking properties, it is not necessary to set the light-blocking properties of the first anti-gloss layer and the second anti-gloss layer, which will be described later, to be high. This increases the design freedom of the first anti-gloss layer and the second anti-gloss layer, and the brightness index (L) ＊ By adjusting the difference between these factors, unwanted light can be blocked without increasing glossiness. 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, for the light-shielding film substrate 20 having light-shielding layers 22 and 23, it is preferable that the light-shielding layers 22 and 23 contain a black component so that the whole contains 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 light-shielding property is imparted.
[0023] Examples of the black component include carbon black, vine black, peach black, bone charcoal, carbon nanotube, silver oxide, zinc oxide, magnetite type iron tetroxide, composite oxide of copper and chromium, composite oxide of copper, chromium, and zinc, black glass, etc., 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 (BaTiO ３ ). From the viewpoint of easy availability, it is preferable to contain carbon black. As carbon black, those produced by various known production methods such as oil furnace black, channel black, gas furnace black, acetylene black, thermal black, ketjen black, etc. are known, but the type is not particularly limited.
[0024] [[ID=VIII]]In one embodiment, the addition amount of the black component is preferably more than 0 part by mass and 50 parts by mass or less, more preferably more than 2 parts by mass and 40 parts by mass or less, and even more preferably more than 5 parts by mass and 30 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 the light-shielding layers 22 and 23.
[0025] In one embodiment, it is preferable that the light-shielding layers 22 and 23 of the light-shielding film substrate 20 having light-shielding properties contain a binder resin and a black component. As the binder resin, a wide range of resins such as thermoplastic resins, thermosetting resins, and photocurable resins can be selected. For thermoplastic resins, thermosetting resins, and photocurable resins, the same resins as the thermoplastic resins, thermosetting resins, and photocurable resins exemplified as the binder resin 30 in the section of the first anti-glare layer and the second anti-glare layer described later are exemplified, and it is preferable to contain one or more selected from them. Among them, thermosetting resins are preferred.
[0026] In one embodiment, the thickness of the light-shielding film substrates 2 and 20 having light-shielding properties 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 properties and having the 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-Glare Layer, Second Anti-Glare Layer] The light-shielding films 1 and 10 according to the first embodiment each have a first anti-glare layer 3 and a second anti-glare layer 4 on the outermost surfaces of the front and back. In the light-shielding films 1 and 10, the glossiness at an incident angle of 60 degrees of at least one of the first anti-glare layer 3 and the second anti-glare layer 4 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-glare layer 3 and the second anti-glare layer 4 is 1% or less.
[0029] In this specification, "glossiness at an incident angle of 60 degrees" means specular glossiness based on a measurement method compliant 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; that is, 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 gloss 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 gloss 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 providing 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 method for adjusting the glossiness at an incident angle of 60 degrees can be adjusted by creating irregularities on the surface. Examples of methods for creating irregularities on the surface include adding a filler, post-processing such as sandblasting, and transferring an uneven shape. In the method of adding a filler, for example, there is a method of adjusting according to the addition amount, particle size, shape, layer thickness, etc. of the filler.
[0034] In one embodiment, the absolute value of the difference in lightness index (L ＊ ) between the first anti-glare layer 3 and the second anti-glare layer 4 is 2 or more, preferably 2.3 or more, more preferably 2.5 or more, and even more preferably 3 or more. In this specification, "lightness index (L ＊ )" means the lightness (L ＊ ) defined in JIS Z 8781-4. Since the absolute value of the difference in 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. In this embodiment, it is sufficient that the absolute value of the difference in 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, and the difference in color tone 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, the lightness index (L ＊ ) of at least one surface of the first anti-glare layer and the second anti-glare layer is preferably 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 the lightness of the surface where the layer is located kept low can be obtained. The lightness index (L ＊The lightness index (L) of the surface of either the first anti-gloss layer or the second anti-gloss 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. In one embodiment, the lightness index (L) of the surface of either the first anti-gloss layer or the second anti-gloss layer is ＊ If the value of the other surface is 25 or less, the lightness index (L) of the other surface is 25 or less. ＊ ) may be greater than 25. In another embodiment, the lightness index (L) of the surfaces of both the first anti-gloss layer and the second anti-gloss layer ＊ The lightness index (L) may be 25 or less, or 20 or less. ＊ From the perspective of easily increasing the difference between the first and second anti-gloss layers, the lightness index (L) of the surface of either the first or second anti-gloss layer is important. ＊ 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-glare layer 3 and the second anti-glare layer 4 preferably contain a binder resin and filler particles. From the viewpoint of easily forming irregularities on the entire surface, it is preferable that the filler particles are dispersed in the binder resin. By including the binder resin and filler particles in the first anti-glare layer 3 and the second anti-glare layer 4, irregularities are formed on the surfaces of the first anti-glare layer 3 and the second anti-glare layer 4, and anti-glare properties can be imparted to the light-shielding films 1 and 10 by scattering incident light from the outside with the irregularities on the surfaces of the first anti-glare layer 3 and the second anti-glare 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) of 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 amount of filler particles added to the second anti-gloss layer 4 tends to be 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, the first anti-gloss layer 3 and the second anti-gloss layer 4 preferably 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 of the first anti-gloss layer 3 (100 parts by mass) and the total amount of the second anti-gloss layer 4 (100 parts by mass). 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 a light-shielding film 1, 10 according to one embodiment. The surface configuration of the light-shielding films 1, 10 will be described below, but the back side of the light-shielding films 1, 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 includes a binder resin 30 and filler particles 31 dispersed in the binder resin 30, and may further include a coloring component (for example, carbon black) 32 dispersed in the binder resin 30. The unevenness of the surface of the first anti-gloss layer 3 is formed by the dispersion and arrangement of a plurality of 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, causing the surface of the binder resin 30 to bulge. The filler particles 31 can be any inorganic particles capable of imparting anti-gloss properties. Examples include inorganic fillers such as silica particles, alumina, aluminum silicate, clay, smectite, calcium carbonate, calcium sulfate, barium sulfate, titanium dioxide, and synthetic zeolite. 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 within 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 to use a black component, such as carbon black, lamp black, vine black, peach black, bone char, carbon nanotubes, silver oxide, zinc oxide, magnetite-type triiron tetroxide, copper and 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 (BaTiO2). ３ It is more preferable that the coloring component 32 be one or more selected from the above. 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 of 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 method for manufacturing the light-blocking 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-blocking 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 liquid, prepared so that a layer of the desired components can be obtained after curing and drying, to the front and back surfaces of the light-blocking film substrate 2 and 20, respectively, and then curing and drying it. If the coating liquid contains a photocurable resin, the first anti-gloss layer 3 and the second anti-gloss layer 4 can be produced by photocuring the coating liquid by light irradiation. If the coating liquid 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, multiple light-shielding members F1 to F6 also act as gap adjustment members between multiple optical members L1 to L6. By setting the gap adjustment members to a predetermined thickness, the distance between optical members L1 to L6 can be adjusted.
[0053] A non-limiting list of exemplary embodiments and combinations of exemplary embodiments of the present disclosure is disclosed below. [1] A light-shielding film comprising a light-shielding film substrate, a first anti-gloss layer, and a second anti-gloss layer, 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, and 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 (preferably greater than 0% and 1.0%, more preferably greater than 0% and 0.8%, even more preferably greater than 0% and 0.5%, 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), and the lightness index (L) of the first anti-gloss layer and the second anti-gloss layer ＊ A light-shielding film in which the absolute value of the difference between (L) is 2 or more (preferably 2.3 or more, more preferably 2.5 or more, and even more preferably 3 or more), and the optical density value of the light-shielding film is 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 brightness index (L) of the surface of at least one of the first anti-gloss layer and the second anti-gloss layer. ＊[1] The light-shielding film according to [1], 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], wherein the first anti-gloss layer and the second anti-gloss layer further contain a coloring component. [8] The light-shielding film according to any one of [1] to [7], wherein the thickness of each 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] The light-shielding film according to any one of [1] to
[11] , which is a shutter, aperture member, or gap adjustment member arranged between a plurality of lenses of an optical component.
[13] A lens unit comprising the light-shielding film according to any one of [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.
[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 a light-shielding base film) A polyethylene terephthalate (PET) film with a thickness of 6 μm (manufactured by Toray Industries, Inc.) was prepared. 100 parts by mass of urethane resin (manufactured by Koshin Chemical Co., Ltd., "KDC-01 Main Agent") as a binder resin was added to 150 parts by mass of carbon black dispersion (manufactured by Mikuni Pigment Co., Ltd., "MHI Black #273"), and then 20 parts by mass of curing agent (manufactured by Koshin Chemical Co., Ltd., "KDC-01 Curing Agent") was added to prepare coating solution (1). Coating solution (1) was applied to both sides of the polyethylene terephthalate film, and solvent drying and heat curing were performed at 100°C to form a pair of light-shielding layers with a thickness of 1.5 μm each after drying, thereby obtaining a light-shielding base film.
[0056] (Manufacturing of light-shielding film) Coating solution (2) was prepared by mixing 100 parts by mass of urethane resin (manufactured by Koshin Chemical Co., Ltd., "KDC-01 main component") as a binder resin, 20 parts by mass of 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"). Coating solution (2) was applied to the surface of a light-shielding substrate film and subjected to solvent drying and heat curing at 100°C to form a first anti-gloss layer with a thickness of 3.5 μm after drying. Furthermore, coating solution (3) was prepared in the same manner as coating solution (2), except that the amount of silica particles was 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] [Measurement of Brightness Index] For each light-shielding film in the examples and comparative examples, the brightness index (L) 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 colorimetric illuminant, in accordance with the measurement method in accordance with JIS Z 8722 and the measurement method based on microspectroscopy. １ ＊ ) and the brightness index (L) of the second anti-gloss layer ２ ＊ ) was measured. Furthermore, the absolute value of the difference in brightness index [[(L ２ ＊ ) - (L １ ＊ ) ] or [ (L １ ＊ ) - (L ２ ＊ We found the absolute value of ).
[0059] [Measurement of gloss at an incident angle of 60 degrees (60-degree gloss)] For each light-shielding film in the examples and comparative examples, the gloss at an incident angle of 60 degrees (60-degree gloss) (A) of the first anti-gloss layer and the gloss at an incident angle of 60 degrees (60-degree gloss) (B) of the second anti-gloss layer 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 gloss [[(B) - (A)] or [(A) - (B)]] was determined.
[0060] [Measurement of Optical Density (OD Value)] For each light-shielding film in the examples and comparative examples, the OD value was measured using a transmittance densitometer (Xrite Corporation, "Model 341C") in the wavelength range of 380 nm to 780 nm.
[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 side on which the first anti-gloss layer is placed and the second side on which the second anti-gloss layer is placed, which is opposite the first side, was evaluated. "1" was assigned if the front and back could be easily distinguished by visual inspection, "2" if the front and back could be distinguished by visual inspection, and "3" if it was difficult to distinguish the front and back by visual inspection. The results of the above measurements and evaluations are shown in Table 1.
[0062]
[0063] As shown in Table 1, the light-shielding film of the example had a front-to-back discrimination rating of "1" and "2", indicating superior front-to-back discrimination. On the other hand, the light-shielding film of the comparative example had a front-to-back discrimination rating of "3", indicating inferior front-to-back discrimination. The light-shielding film of the example had a lightness index (L) of the second anti-gloss layer. ２ ＊ 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.
[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.
[0065] F1-F6 Light-shielding members L1-L6 Optical members 1, 10 Light-shielding films 2, 20 Light-shielding film substrates 3 First anti-gloss layer 4 Second anti-gloss layer 21 Film members 22, 23 Light-shielding layers 30 Binder resin 31 Filler particles 32 Coloring components 40 Lens unit 41 Housing (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, 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 is ＊ A light-shielding film in which the absolute value of the difference between ) is 2 or more, and the optical density value of the light-shielding film is 4 or more.
2. The lightness index (L) of at least one surface 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 contain 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 according to claim 1 or 2.