JP7569155B2 - Resin composition for low-reflection light-shielding layer, and low-reflection light-shielding layer and low-reflection light-shielding layer laminate using the same - Google Patents

Description

The present invention relates to a novel resin composition for low-reflection light-shielding layers, as well as low-reflection light-shielding layers and low-reflection light-shielding layer laminates using the same.

In various optical devices such as single-lens reflex cameras, compact cameras, video cameras, and smartphones, light-shielding materials with high light-shielding properties and low gloss are used from the viewpoint of removing unnecessary incident light and reflected light and suppressing the occurrence of halation, lens flare, ghosting, and the like. For example, various optical devices are equipped with lens units and camera modules in which light-shielding plates or light-shielding rings for cutting out unnecessary light are interposed between lenses. In addition, light-shielding materials are used in the shutters and aperture components of various optical devices such as single-lens reflex cameras, compact cameras, and video cameras from the viewpoint of preventing the occurrence of halation and ghosting due to external light, and the like.

On the other hand, due to the remarkable progress in sensing technology in recent years, the introduction of advanced sensing technology is being considered for various moving bodies (hereinafter sometimes referred to as "mobile vehicles") such as automobiles, trains, steam trains, ships, cargo ships, aircraft, spacecraft, rockets, transportation equipment, and vehicles. As one example, there is progress in the development of automobiles that are equipped with optical sensors such as lens units (camera modules) with image sensors and infrared sensors in the passenger compartment to detect obstacles (e.g. other vehicles, pedestrians, guardrails, houses, etc.) that exist in front of the vehicle.

Traditionally, thin metal films coated with black paint have been used as light-shielding materials in various optical devices. However, in recent years, there has been interest in using lightweight plastic materials as an alternative.

As such a non-metallic light-shielding member, the applicant has proposed a light-shielding member for optical devices having a film substrate and a light-shielding film formed on at least one side of the substrate, the light-shielding film containing a binder resin, carbon black, a particulate lubricant, and fine particles, the binder resin and lubricant contents being 70% by weight or more and 5-15% by weight, respectively, and the lubricant having a density greater than that of the fine particles (see Patent Document 1).

JP 2011-123255 A

In the technology of Patent Document 1, the light-shielding film contains 70% by weight or more of binder resin and 2-5% by weight of fine particles such as silica, and further contains 5-15% by weight of a specific lubricant with a low density. However, in this formulation, the diffuse reflectance (550 nm) including regular reflection and the diffuse reflectance (905 nm) including regular reflection of the light-shielding film are both large at 5% or more, and there is room for improvement in terms of surface reflectance. In addition, in recent years, from the viewpoint of design, low gloss and black designs with a high-class feel are becoming increasingly popular, and there is a demand for harmony with them. However, in the technology of Patent Document 1, for example, the L ^* value in the CIE 1976 L ^* a ^* b ^* color system is 25 or more, and there is also room for improvement in terms of blackness.

In addition, the surface reflectance of the light-shielding film generally tends to decrease as the surface roughness (Ra, Rz, etc.) of the light-shielding film increases. On the other hand, the L ^* value in the CIE 1976 L ^* a ^* b ^* color system tends to increase as the surface roughness (Ra, Rz, etc.) of the light-shielding film increases. That is, in the design guideline described in Patent Document 1, when the surface roughness (Ra, Rz, etc.) of the light-shielding film is increased to reduce the surface reflectance of the light-shielding film, the L ^* value increases accordingly, and it is not possible to simultaneously achieve the three of low surface reflectance, low L ^* value, and low surface roughness. Therefore, a new design guideline capable of simultaneously achieving these three is required.

The present invention has been made in view of the above problems. That is, the present invention aims to provide a resin composition having a new composition capable of realizing a low-reflection light-shielding layer having a small surface reflectance and L ^* value. Another object of the present invention is to provide a resin composition having a new composition capable of realizing a low-reflection light-shielding layer having a small surface reflectance, L ^* value, and surface roughness.

Another object of the present invention is to provide a low-reflection light-shielding layer and a low-reflection light-shielding layer laminate having a small surface reflectance and L ^* value. Another object of the present invention is to provide a low-reflection light-shielding layer and a low-reflection light-shielding layer laminate having a small surface reflectance, L ^* value, and surface roughness. Furthermore, the present invention has a more preferred object of providing a high-performance low-reflection member, a low-reflection member for optical equipment, and a light-shielding low-reflection member for optical equipment using the low-reflection light-shielding layer and the low-reflection light-shielding layer laminate.

The inventors conducted extensive research into the film surface shape and optical properties in order to solve the above problems, and discovered a resin composition that is different from that of conventional techniques. They discovered that this new resin composition can solve the above problems, and thus completed the present invention.

[1] A resin composition for a low-reflection light-shielding layer, which contains at least a binder resin, a colorant, resin particles, and a dispersion medium, and in which the binder resin has a total content of 1 to 30 mass% in terms of solid content relative to the total solid content, the colorant has a total content of 0.1 to 35 mass% in terms of solid content relative to the total solid content, and the resin particles have a total content of 50 to 95 mass% in terms of solid content relative to the total solid content.

[2] The resin composition for a low reflection light-shielding layer according to the above [1], wherein the resin particles have an average particle diameter D ₅₀ of 3 to 20 μm.
[3] The resin composition for a low reflection light-shielding layer according to [1] or [2], wherein the resin particles contain colored resin particles.

[4] A low-reflection light-shielding layer that contains at least a binder resin, a colorant dispersed in the binder resin, and resin particles dispersed in the binder resin, the binder resin content is 1 to 30% by mass in total relative to the total amount in solid content conversion, the colorant content is 0.1 to 35% by mass in total relative to the total amount in solid content conversion, and the resin particles content is 50 to 95% by mass in total relative to the total amount in solid content conversion.

[5] The low reflection light-shielding layer according to the above [4], wherein the resin particles contain colored resin particles.
[6] The low reflection light-shielding layer according to the above [4] or [5], wherein the resin particles have an average particle diameter D ₅₀ of 3 to 20 μm.

[7] The low reflection light-shielding layer according to any one of the above [4] to [6], wherein the surface roughness Ra of one surface side is 0.2 to 0.7 μm.
[8] The low reflection light-shielding layer according to any one of the above [4] to [7], wherein the surface roughness Rz of one surface side is 2.0 to 5.0 μm.
[9] The low reflection light-shielding layer according to any one of the above [4] to [8], wherein the diffuse reflectance (including regular reflection) at 550 nm on one surface side is 0.0% or more and less than 3.0%.
[10] The low reflection light-shielding layer according to any one of the above [4] to [9], wherein the 905 nm diffuse reflectance (including regular reflection) on one surface side is 0.0% or more and less than 3.0%.
[11] The low reflection light-shielding layer according to any one of [4] to [10], wherein one surface side has an L ^* value of 0 to 18 in the CIE 1976 L ^* a ^* b ^* color system.

[12] The low-reflection light-shielding layer according to any one of [4] to [11] above, which has an optical density OD of 0.5 or more.
[13] The low reflection light-shielding layer according to any one of [4] to [12] above, having a thickness of 1 to 30 μm.

[14] A low-reflection light-shielding layer laminate comprising a substrate and the low-reflection light-shielding layer according to any one of [4] to [13] above, provided on at least one main surface side of the substrate.
[15] A low-reflection light-shielding layer laminate comprising a base film, a low-reflection light-shielding layer according to any one of [4] to [13] provided on one main surface side of the base film, and a low-reflection light-shielding layer according to any one of [4] to [13] provided on the other main surface side of the base film.

According to the present invention, a resin composition having a new composition can be provided that can realize a low-reflection light-shielding layer having a small surface reflectance and surface glossiness. In addition, according to a preferred embodiment of the present invention, a resin composition having a new composition can be provided that can realize a low-reflection light-shielding layer having a small surface reflectance, L ^* value, and surface roughness. According to the present invention, a low-reflection light-shielding layer and a low-reflection light-shielding layer laminate having a small surface reflectance and surface glossiness can be provided, and according to a preferred embodiment of the present invention, a low-reflection light-shielding layer and a low-reflection light-shielding layer laminate having a small surface reflectance, L ^* value, and surface roughness can be provided. Therefore, for example, deterioration or a decrease in the captured image and detection accuracy of optical sensors can be suppressed, and it is possible to further improve the captured image and detection accuracy. In addition, since a low-reflection light-shielding layer having a darker appearance can be realized, the design of various optical devices equipped with this can be improved. According to the present invention, a high-performance low-reflection member, a low-reflection member for optical devices, and a light-shielding low-reflection member for optical devices having a novel design that did not exist in the past can also be realized.

1 is a schematic cross-sectional view showing a low-reflection light-shielding layer 21 and a low-reflection light-shielding layer laminate 100 according to an embodiment.

The following describes in detail the embodiments of the present invention with reference to the drawings. Unless otherwise specified, the positional relationships, such as up, down, left, and right, are based on the positional relationships shown in the drawings. Furthermore, the dimensional ratios of the drawings are not limited to those shown. However, the following embodiments are merely examples for explaining the present invention, and the present invention is not limited to these. In this specification, for example, the notation of a numerical range such as "1 to 100" includes both the upper limit value "100" and the lower limit value "1". The same applies to the notation of other numerical ranges.

The resin composition for a low-reflection light-shielding layer according to the first embodiment of the present invention (hereinafter, sometimes simply referred to as the "resin composition") contains at least a binder resin, a colorant, resin particles, and a dispersion medium. The binder resin, colorant, and resin particles may be dispersed in the dispersion medium, but a portion of these may also be dissolved in the dispersion medium.

As the binder resin, those known in the art can be used, and the type is not particularly limited. Specific examples include thermoplastic resins or thermosetting resins such as poly(meth)acrylic acid resins, polyester resins, polyvinyl acetate resins, polyvinyl chloride resins, polyvinyl butyral resins, cellulose resins, polystyrene/polybutadiene resins, polyurethane resins, alkyd resins, acrylic resins, unsaturated polyester resins, epoxy ester resins, epoxy resins, epoxy acrylate resins, urethane acrylate resins, polyester acrylate resins, polyether acrylate resins, phenol resins, melamine resins, urea resins, and diallyl phthalate resins, but are not particularly limited thereto. Thermoplastic elastomers, thermosetting elastomers, ultraviolet curable resins, and electron beam curable resins can also be used. These can be used alone or in combination of two or more. The binder resin can be appropriately selected and used depending on the required performance and application. For example, in applications where heat resistance is required, thermosetting resins are preferred.

The content (total amount) of the binder resin in the resin composition can be appropriately set to a level necessary for film formation, and is not particularly limited. In consideration of the blending balance with other essential components and optional components, from the viewpoint of realizing a low-reflection light-shielding layer having a better surface reflectance and L ^* value, and furthermore a lower surface roughness as necessary, the content (total amount) of the binder resin is preferably 1 to 30 mass% in total, more preferably 2 to 25 mass% in total, even more preferably 3 to 20 mass% in total, and particularly preferably 5 to 15 mass% in total, in terms of solid content relative to the total solid content of the resin composition. In addition, when the colorant or resin particles contain binder resin components, these binder resin components are also incorporated into the total amount of the binder resin in the content ratio referred to here.

As the coloring material, pigments and dyes known in the art can be used, and the type is not particularly limited. By appropriately selecting the type, particle size, and amount of the coloring material, the light blocking property and light transmittance can be adjusted. Specifically, magnetite black, copper-iron-manganese black, titanium black, carbon black, aniline black, etc. can be mentioned, but are not particularly limited to these. As the coloring material, black inorganic pigments and black organic pigments are preferably used from the viewpoint of light blocking property, light transmittance, ease of adjustment of color tone, etc. These can be used alone, or two or more types can be used in combination. Among these, inorganic pigments are preferable as the coloring material, and specifically, titanium black, carbon black, and aniline black are preferable, and carbon black and aniline black are more preferable. As carbon black, oil furnace black, lamp black, channel black, gas furnace black, acetylene black, thermal black, ketjen black, etc., which are produced by various known manufacturing methods, are known, but the type is not particularly limited. From the viewpoint of imparting conductivity and preventing static electricity buildup, conductive carbon black is particularly preferably used as a colorant. Carbon black has a long history, and various grades of carbon black and carbon black dispersions are commercially available from, for example, Mitsubishi Chemical Corporation, Asahi Carbon Co., Ltd., Mikuni Color Co., Ltd., Resino Color Co., Ltd., Cabot Corporation, DEGUSSA Corporation, etc., and an appropriate selection may be made from these depending on the required performance and application. These may be used alone or in combination of two or more types.

The particle size of the colorant is not particularly limited and can be appropriately set depending on the type of colorant used, the required performance, etc. For example, when the colorant is carbon black, the average particle diameter _D50 is preferably 0.01 to 2.0 μm, more preferably 0.05 to 1.0 μm, and even more preferably 0.08 to 0.5 μm. In this specification, the average particle diameter _D50 means the volume-based median diameter ( _D50 ) measured by a laser diffraction particle size distribution measuring device (for example, Shimadzu Corporation: SALD-7000, etc.).

The content (total amount) of the coloring material in the resin composition can be appropriately set according to the required performance such as light shielding property and low gloss, and is not particularly limited. In consideration of the blending balance with other essential components and optional components, from the viewpoint of realizing a low-reflection light-shielding layer having a better surface reflectance and L ^* value, and furthermore a lower surface roughness as necessary, the content (total amount) of the coloring material is preferably 0.1 to 35 mass% in total, more preferably 1 to 30 mass% in total, even more preferably 3 to 20 mass% in total, and particularly preferably 5 to 15 mass% in total, in terms of solid content relative to the total solid content of the resin composition. Note that the content of the coloring material when colored resin particles are used as the resin particles is the sum of the mass of the above-mentioned coloring material and the mass of the coloring material contained in the resin particles (total amount of coloring material in the composition).

As the resin particles, those known in the art can be used, and the type is not particularly limited. Specific examples include polymethyl methacrylate-based, polystyrene-based, polyester-based, polyurethane-based, silicone resin-based, fluororesin-based such as polyvinylidene fluoride, and rubber-based resin particles, but are not particularly limited thereto. These can be used alone, or two or more types can be used in combination. In addition, the appearance of the resin particles may be transparent, semi-transparent, or opaque, and is not particularly limited. In addition, the resin particles may be colorless, or may be colored. For example, by using resin particles (colored resin particles) colored in black, gray, purple, blue, brown, red, green, or the like, a low-reflection light-shielding layer with high optical density and color saturation can be realized even if the amount of colorant used is relatively small. In addition, by using colored resin particles, the L ^* value can be significantly reduced, especially compared to the case of using inorganic particles such as silica.

From the viewpoint of obtaining the above-mentioned surface reflectance and L ^* value, it is preferable that the resin particles have a relatively coarse particle size. Specifically, the average particle size _D50 of the resin particles is preferably 1 μm or more, more preferably 2 μm or more, even more preferably 4 μm or more, and particularly preferably 5 μm or more. The upper limit is 30 μm or less, more preferably 20 μm or less, and particularly preferably 15 μm or less. In addition, it may be required from the viewpoint of productivity, handling, etc. to use resin particles having an average particle size _D50 that suppresses the aggregation of resin particles during coating, or that does not make the particle size of the aggregates excessively large even if the resin particles are aggregated.

The content (total amount) of the resin particles in the resin composition can be appropriately set according to the required performance such as light shielding property and low gloss, and is not particularly limited. In consideration of the blending balance with other essential components and optional components, from the viewpoint of realizing a low-reflection light-shielding layer having a better surface reflectance and L ^* value, and furthermore a lower surface roughness as required, the content (total amount) of the resin particles is preferably 50 to 95 mass% in total, more preferably 55 to 90 mass% in total, and even more preferably 60 to 85 mass% in total, in terms of solid content relative to the total solid content of the resin composition. Note that the content of the resin particles when colored resin particles are used as the resin particles is based on the mass of the resin particles including the colorant contained in the resin particles.

In addition, the resin composition of this embodiment may contain known coloring materials in addition to the coloring materials and resin particles described above in order to control the color tone. Examples of the coloring material include, but are not limited to, diarylmethane-based materials; triarylmethane-based materials; thiazole-based materials; methine-based materials such as merocyanine and pyrazolone methine; azomethine-based materials such as indoaniline, acetophenone azomethine, pyrazoloazomethine, imidazole azomethine, and imidazoazomethine; xanthene-based materials; oxazine-based materials; cyanomethylene-based materials such as dicyanostyrene and tricyanostyrene; thiazine-based materials; azine-based materials; acridine-based materials; benzene azo-based materials; azo-based materials such as pyridone azo, thiophene azo, isothiazole azo, pyrrole azo, imidazole azo, thiadiazole azo, triazole azo, and diaz azo; spiropyran-based materials; indolinospiropyran-based materials; fluoran-based materials; naphthoquinone-based materials; anthraquinone-based materials; and quinophthalone-based materials. For example, known black, blue, green, yellow, and red colorants can be used alone or in combination of two or more. When colorants are used, the content (total amount) of the colorants can be appropriately set according to the required performance and is not particularly limited, but taking into consideration the blending balance with other essential and optional components, the total solid content of the resin composition is preferably 0.1 to 10 mass%, more preferably 0.5 to 5 mass%, and even more preferably 1 to 3 mass%.

The resin composition may also contain a known matting agent (flatting agent) to adjust the gloss, color tone, etc., of the resin composition. Examples of matting agents include kaolin, calcined kaolin, calcined clay, uncalcined clay, silica (e.g., natural silica, fused silica, amorphous silica, hollow silica, wet silica, synthetic silica, aerosil, etc.), aluminum compounds (e.g., boehmite, aluminum hydroxide, alumina, hydrotalcite, aluminum borate, aluminum nitride, etc.), magnesium compounds (e.g., magnesium aluminometasilicate, magnesium carbonate, magnesium oxide, magnesium hydroxide, etc.), calcium compounds (e.g., carbonate, magnesium oxide, magnesium hydroxide, etc.), calcium compounds (e.g., calcium carbonate, magnesium oxide, magnesium hydroxide, etc.), calcium carbonate, magnesium oxide, magnesium hydroxide, magnesium oxide, magnesium hydroxide, magnesium oxide, magnesium hydroxide, magnesium oxide, magnesium oxide, magnesium oxide, magnesium oxide, magnesium oxide, magnesium oxide, magnesium oxide, magnesium oxide, magnesium oxide, magnesium oxide, magnesium oxide, calcium carbonate ... Examples of the stannate include calcium, calcium hydroxide, calcium sulfate, calcium sulfite, calcium borate, etc.), molybdenum compounds (e.g., molybdenum oxide, zinc molybdate, etc.), talc (e.g., natural talc, calcined talc, etc.), mica, titanium oxide, zinc oxide, zirconium oxide, barium sulfate, zinc borate, barium metaborate, sodium borate, boron nitride, aggregated boron nitride, silicon nitride, carbon nitride, strontium titanate, barium titanate, and zinc stannate, but are not particularly limited thereto. These may be used alone or in combination of two or more. When a matting agent is used, the content (total amount) of the matting agent can be set appropriately according to the required performance and is not particularly limited, but from the viewpoint of realizing a low-reflection light-shielding layer with better surface reflectance and surface glossiness, taking into consideration the blending balance with other essential and optional components, the content is preferably 0.1 to 10 mass% in total, more preferably 0.5 to 5 mass% in total, and even more preferably 1 to 3 mass% in total, calculated as solid content relative to the total solid content of the resin composition.

Furthermore, the resin composition may contain various additives known in the art. Specific examples include, but are not limited to, lubricants, conductive agents, flame retardants, antibacterial agents, antifungal agents, antioxidants, plasticizers, resin curing agents, curing agents, curing accelerators, leveling agents, flow control agents, defoamers, dispersants, etc. Lubricants include, but are not limited to, hydrocarbon-based lubricants such as polyethylene, paraffin, and wax; fatty acid-based lubricants such as stearic acid and 12-hydroxystearic acid; amide-based lubricants such as stearic acid amide, oleic acid amide, and erucic acid amide; ester-based lubricants such as butyl stearate and stearic acid monoglyceride; alcohol-based lubricants; solid lubricants such as metal soap, talc, and molybdenum disulfide; and polytetrafluoroethylene wax. Among these, organic lubricants are particularly preferred. In addition, when an ultraviolet-curable resin or an electron beam-curable resin is used as the binder resin, a sensitizer or an ultraviolet absorber, such as n-butylamine, triethylamine, or tri-n-butylphosphine, may be used. These may be used alone or in combination of two or more. The content ratio of these is not particularly limited, but is generally preferably 0.01 to 5 mass% each in terms of solid content relative to the total solid content of the resin composition.

The dispersion medium is not particularly limited, but includes water; ketone-based solvents such as methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; ester-based solvents such as methyl acetate, ethyl acetate, and butyl acetate; ether-based solvents such as methyl cellosolve and ethyl cellosolve; alcohol-based solvents such as methyl alcohol, ethyl alcohol, and isopropyl alcohol, as well as mixed solvents thereof. The amount of the dispersion medium used is not particularly limited as long as it is sufficient to form a low-reflection light-shielding layer, but from the viewpoint of handleability and workability, it is generally adjusted so that the total solid content of the resin composition is 10 to 90% by mass, preferably 20 to 80% by mass, and more preferably 25 to 70% by mass.

The low-reflection light-shielding layer 21 can be obtained by applying the above-mentioned resin composition to a predetermined shape. FIG. 1 is a cross-sectional view showing a main part of a low-reflection light-shielding layer laminate 100 including the low-reflection light-shielding layer 21. The low-reflection light-shielding layer laminate 100 includes a substrate 11, a low-reflection light-shielding layer 21 provided on one main surface 11a of the substrate 11, and an adhesive layer 31 provided on the other surface 11b of the substrate 11. That is, the low-reflection light-shielding layer laminate 100 of this embodiment has a laminated structure (three-layer structure) in which the low-reflection light-shielding layer 21, the substrate 11, and the adhesive layer 31 are arranged at least in this order. In this laminated structure, the low-reflection light-shielding layer 21 is disposed on the outermost surface of the front side, and the adhesive layer 31 is disposed on the outermost surface of the back side, and the low-reflection light-shielding layer 21 and the adhesive layer 31 are disposed in a state of being exposed on the outermost surfaces of the front side and the back side, respectively. In addition, the surface 21a of the low-reflection light-shielding layer 21 may be provided with any layer, such as an antistatic layer, a protective layer, an antifouling layer, an antibacterial layer, an antireflection film, or a printed layer, as necessary, within the scope of the present invention. In addition, the surface 21a of the low-reflection light-shielding layer 21 may be subjected to any surface treatment, such as an antistatic treatment, an antifouling treatment, an antibacterial treatment, or an antireflection treatment, as necessary, within the scope of the present invention.

In this specification, "provided on one (other) surface side of" means not only the embodiment in which the low-reflection light-shielding layer 21 or the adhesive layer 31 is directly placed on the surface of the substrate 11 (for example, the main surface 11a or the main surface 11b) as in this embodiment, but also the embodiment in which the low-reflection light-shielding layer 21 or the adhesive layer 31 is disposed apart from the substrate 11 with an optional layer (for example, a primer layer, an adhesive layer, a conductive layer, etc.) not shown being interposed between the surface 11a of the substrate 11 and the low-reflection light-shielding layer 21 or between the surface 11b of the substrate 11 and the adhesive layer 31. In addition, a laminated structure having at least the low-reflection light-shielding layer 21 and the adhesive layer 31 means not only the structure in which only the low-reflection light-shielding layer 21 and the adhesive layer 31 are directly laminated on the substrate 11, but also the structure in which any layer as described above is further provided between the layers of the three-layer structure.

The type of the substrate 11 is not particularly limited as long as it is capable of supporting the low-reflection light-shielding layer 21 and the adhesive layer 31. Specific examples of the substrate 11 include, but are not limited to, metals, alloys, resin molded bodies, resin films, nonwoven fabrics, and glass. As metals and alloys, metal materials including aluminum, magnesium, iron, and alloys thereof are preferably used. In addition, from the standpoints of dimensional stability, mechanical strength, and weight reduction, synthetic resins are preferably used as the substrate 11. Specific examples of synthetic resins include polyester; ABS (acrylonitrile-butadiene-styrene); polyimide; polyamide; polyamideimide; polystyrene; polycarbonate; (meth)acrylic; nylon; polyolefins such as polyethylene and polypropylene; addition copolymers of calebornenes and α-olefins, hydrogenated ring-opening metathesis polymers of norbornenes, cycloolefins such as cyclopentene, cyclohexene, 3-methylcyclohexene, and cyclooctene; cellulose; polysulfone; polyphenylene sulfide; polyethersulfone; and polyetheretherketone resins, but are not limited thereto. In this specification, the term "(meth)acrylic" refers to a concept including both acrylic and methacrylic. These may be used alone or in any combination of two or more. In addition, multilayer molded bodies (multicolor molded bodies) and laminated films using any combination of these may also be suitably used. Among these, as the substrate 11, from the viewpoints of dimensional stability, mechanical strength, and weight reduction, a substrate film of a synthetic resin is preferred, and polyester film, polyimide film, polycarbonate film, (meth)acrylic film, and laminated film of any combination thereof are more preferably used. In particular, uniaxially or biaxially stretched films, especially biaxially stretched polyester films, are particularly preferred because of their excellent mechanical strength and dimensional stability. In addition, for heat-resistant applications, polyimide films, polyamideimide films, and polyamide films are particularly preferred, and polyimide films and polyamideimide films are most preferred.

The thickness of the substrate 11 can be appropriately set according to the required performance and the application, and is not particularly limited. By providing the low-reflection light-shielding layer 21 on the substrate 11, for example, the substrate 11 which is a molded body, or the substrate film which is the film-like substrate 11, or the substrate 11 which is a film-like or layer-like substrate, can be given a surface with low surface reflectance and surface gloss. When using a substrate film which is the film-like substrate 11, the thickness of the substrate 11 is set as a guideline from the viewpoint of weight reduction and thinning. From the viewpoint of strength, rigidity, etc., the thickness of the substrate 11 is preferably 36 μm or more and less than 250 μm. On the other hand, from the viewpoint of further weight reduction and thinning, the thickness of the substrate 11 is preferably 1 μm or more and 50 μm or less, more preferably 1 μm or more and 25 μm or less, even more preferably 4 μm or more and 10 μm or less, and particularly preferably 5 μm or more and 7 μm or less. In addition, in order to improve adhesion to the low-reflection light-shielding layer 21 and the adhesive layer 31, various known surface treatments such as anchor treatment, corona treatment, and antistatic treatment can be performed on the surface of the substrate 11 as necessary.

The appearance of the substrate 11 may be transparent, semi-transparent, or opaque, and is not particularly limited. For example, a foamed synthetic resin film such as a foamed polyester film or a synthetic resin film containing various pigments can be used. For example, a synthetic resin film containing one or more dark pigments or dyes such as black, gray, purple, blue, brown, red, and green can be used to form a film with high optical density. The pigments and dyes used here can be appropriately selected from those known in the industry, and the type is not particularly limited. For example, black pigments include black resin particles, magnetite black, copper-iron-manganese black, titanium black, carbon black, and the like. Among these, black resin particles, titanium black, and carbon black are preferred because of their excellent hiding properties. These can be used alone or in combination of two or more. When the substrate 11 contains a pigment or dye, the content ratio can be appropriately set according to the required performance and application, and is not particularly limited. From the viewpoints of dimensional stability, mechanical strength, weight reduction, etc., the total content of the pigment and dye is preferably 0.3 to 15 mass % relative to the total amount of the base material 11, more preferably 0.4 to 12 mass %, and even more preferably 0.5 to 10 mass %.

The method for forming the low-reflection light-shielding layer 21 can be any known method, and is not particularly limited. The above-mentioned resin composition is applied to the substrate 11 to a predetermined thickness, dried, and, if necessary, subjected to ionizing radiation treatment, heat treatment, and/or pressure treatment, etc., to obtain the low-reflection light-shielding layer 21. From the viewpoint of easily and inexpensively producing a high-performance low-reflection light-shielding layer 21 on the substrate 11 with good reproducibility, coating methods such as doctor coating, dip coating, roll coating, bar coating, die coating, blade coating, air knife coating, kiss coating, spray coating, and spin coating are preferably used.

The thickness of the low-reflection light-shielding layer 21 can be set appropriately depending on the required performance and application, and is not particularly limited. From the viewpoint of a balance between high optical density, light weight, and thin film, the thickness is preferably 1 μm or more, more preferably 2 μm or more, even more preferably 3 μm or more, and particularly preferably 4 μm or more, and the upper limit is preferably 30 μm or less, more preferably 25 μm or less, even more preferably 20 μm or less, and particularly preferably 15 μm or less.

The light-shielding property of the low-reflection light-shielding layer 21 of this embodiment may be appropriately set according to the required performance, and is not particularly limited. From the viewpoint of having higher light-shielding property, the low-reflection light-shielding layer 21 preferably has an optical density OD of 0.5 or more, more preferably an optical density OD of 1.0 or more, even more preferably an optical density OD of 1.7 or more, and particularly preferably an optical density OD of 2.0 or more. In this specification, the optical density (OD) is a value obtained by measurement using an optical densitometer (X-Rite 361T: X-Rite, Inc.) and an orthofilter in accordance with ISO 5-2.

The adhesive layer 31 is provided on the surface 11b of the substrate 11 described above, and is a layer that adhesively bonds to an adherend (not shown). By adhesively bonding the adhesive layer 31 to the adherend in this manner, it is possible to impart a surface with low reflectivity and low gloss to the adherend. The material constituting the adhesive layer 31 may be any material known in the industry, and may be appropriately selected according to the surface material of the adherend (resin molded body, multilayer laminate using this resin molded body, nonwoven fabric, skin material, metal, alloy, etc.), and the type is not particularly limited. For example, rubber-based adhesives, acrylic-based adhesives, olefin-based adhesives, silicone-based adhesives, and urethane-based adhesives are preferably used.

The thickness of the adhesive layer 31 can be set appropriately depending on the required performance and application, and is not particularly limited, but from the viewpoint of a balance between weight reduction and thinning, it is preferably 0.1 μm or more, more preferably 0.2 μm or more, even more preferably 0.5 μm or more, particularly preferably 1.0 μm or more, and most preferably 3.0 μm or more, and the upper limit is preferably 40 μm or less, more preferably 30 μm or less, even more preferably 25 μm or less, particularly preferably 20 μm or less, and most preferably 10 μm or less.

As described above in detail, the low-reflection light-shielding layer laminate 100 of the present embodiment includes the low-reflection light-shielding layer 21 formed from the specific resin composition described above, and functions as a laminate film having a small surface reflectance and L ^* value, and in a more preferred embodiment, functions as a laminate film having a small surface reflectance, L ^* value, and surface roughness. Therefore, by using the low-reflection light-shielding layer laminate 100 of the present embodiment as a low-reflection member, a low-reflection member for optical equipment, a light-shielding member for optical equipment, or the like, it is possible to suppress deterioration or a decrease in the captured image and detection accuracy of, for example, optical sensors.

Here, the surface reflectance of the surface 21a side of the low reflection light-shielding layer laminate 100 (low reflection light-shielding layer 21) of this embodiment can be appropriately set according to the required performance, and is not particularly limited. From the viewpoint of reducing the surface reflectance and L ^* value and reducing the specular gloss, the 550 nm diffuse reflectance (including regular reflection) of the surface 21a side of the low reflection light-shielding layer laminate 100 (low reflection light-shielding layer 21) is preferably less than 3.0%, more preferably less than 2.8%, even more preferably less than 2.6%, and particularly preferably less than 2.4%. Here, the lower limit of the 550 nm diffuse reflectance is not particularly limited, but the lower the better, and therefore, it is sufficient if it is 0.0% or more. Similarly, the 905 nm diffuse reflectance (including regular reflection) of the surface 21a side of the low reflection light-shielding layer laminate 100 (low reflection light-shielding layer 21) is preferably less than 3.0%, more preferably less than 2.8%, even more preferably less than 2.6%, and particularly preferably less than 2.4%. Here, the lower limit of the 905 nm diffuse reflectance is not particularly limited, but the lower the better, so it is sufficient that it is 0.0% or more. In this specification, the 550 nm diffuse reflectance and the 905 nm diffuse reflectance (including specular reflection) refer to values obtained by measuring the diffuse reflectance (including specular reflection) (%) when light of each wavelength is incident using a spectrophotometer (e.g., SolidSpec-3700 (manufactured by Shimadzu Corporation)).

In addition, the L ^* value in the CIE 1976 L ^* a ^* b ^* color system on the surface 21a side of the low-reflection light-shielding layer laminate 100 (low-reflection light-shielding layer 21) of this embodiment may be appropriately set according to the required performance, and is not particularly limited. From the viewpoint of obtaining a blacker appearance and from the viewpoint of a balance between low gloss, low reflectivity, light absorption, etc., the L ^* value on the surface 21a side of the low-reflection light-shielding layer laminate 100 (low-reflection light-shielding layer 21) is preferably 0 to 18, more preferably 16 or less, even more preferably 14 or less, and particularly preferably 13 or less. Here, the L ^* value on the surface 21a side of the low-reflection light-shielding layer laminate 100 (low-reflection light-shielding layer 21) may be the same as the L ^* value of the low-reflection film or light-shielding film of the conventional technology (for example, 19 to 30), but it can be adjusted to a relatively small value by forming a film from the above-mentioned specific resin composition, which is one of the features not found in the conventional technology. In this specification, the L ^* value in the L ^* a ^* b ^* color system refers to a value measured in accordance with JIS Z 8720:2012 using CIE standard illuminant D ₆₅ with a spectrophotometer (e.g., ZE6000 (manufactured by Nippon Denshoku Industries Co., Ltd.)).

On the other hand, the surface roughness Ra (arithmetic mean roughness) of the surface 21a side of the low-reflection light-shielding layer laminate 100 (low-reflection light-shielding layer 21) of this embodiment can be appropriately set according to the required performance and is not particularly limited, but from the viewpoint of reducing the surface reflectance and L ^* value and reducing the specular gloss, it is preferably 0.2 to 0.7 μm, more preferably 0.2 to 0.6 μm, even more preferably 0.2 to 0.5 μm, and particularly preferably 0.3 to 0.5 μm. Note that, as is well known in the art, the surface roughness Ra is a parameter in the height direction of the surface unevenness and represents the average absolute value of the height Zx of the roughness curve over the reference length. Here, the surface roughness Ra of the surface 21a side of the low-reflection light-shielding layer laminate 100 (low-reflection light-shielding layer 21) may be similar to the surface roughness Ra of the low-reflection films and light-shielding films of the prior art (e.g., 1.0 to 2.0 μm); however, by forming the film from the specific resin composition described above, it can be adjusted to a relatively small value, which is one of the features not found in the prior art.

The surface roughness Rz (maximum height) of the surface 21a side of the low-reflection light-shielding layer laminate 100 (low-reflection light-shielding layer 21) of this embodiment can be appropriately set according to the required performance and is not particularly limited, but from the viewpoint of reducing the surface reflectance and L ^* value and reducing the specular gloss, it is preferably 2.0 to 5.0 μm, more preferably 2.1 to 4.8 μm, even more preferably 2.2 to 4.6 μm, and particularly preferably 2.5 to 4.5 μm. Note that, as is well known in the art, the surface roughness Rz of the low-reflection light-shielding layer 21 is a parameter in the height direction of the surface unevenness, and represents the sum of the maximum values of the convexity height Zp and the concaveity depth Zv of the roughness curve in the reference length. Here, the surface roughness Rz of the surface 21a side of the low-reflection light-shielding layer laminate 100 (low-reflection light-shielding layer 21) may be similar to the surface roughness Rz of the low-reflection films and light-shielding films of the conventional technology (e.g., 6 to 12 μm), but by forming the film from the specific resin composition described above, it can be adjusted to a relatively small value, which is one of the features not found in the conventional technology.

On the other hand, the surface roughness RSm of the surface 21a side of the low reflection light-shielding layer laminate 100 (low reflection light-shielding layer 21) of this embodiment can be appropriately set according to the required performance and is not particularly limited, but from the viewpoint of reducing the surface reflectance and L ^* value, it is preferably 20 to 70 μm, more preferably 30 to 65 μm, and even more preferably 35 to 60 μm. Here, the surface roughness RSm is a parameter in the length direction (horizontal direction) of the surface unevenness, and represents the average of the length Xs of the roughness curve element in the reference length. In other words, it can be understood as the average wavelength of the surface unevenness. The larger the surface roughness RSm, the smaller the surface reflectance and surface glossiness, and the smaller the specular glossiness on the wide angle side tends to be. Note that the length direction of the surface unevenness means one direction in the plane of the low reflection light-shielding layer 21 determined when measuring the surface roughness RSm. For example, in the case of a low reflection light-shielding layer 21 that is rectangular in plan view, it may be either the vertical direction or the horizontal direction in the plane, and the direction is not particularly limited.

In addition, the surface roughness Rsk of the surface 21a side of the low reflection light-shielding layer laminate 100 (low reflection light-shielding layer 21) of this embodiment can be appropriately set according to the required performance, and is not particularly limited, but from the viewpoint of reducing the surface reflectance and L ^* value, it is preferably 0.1 to 3.0 μm, more preferably 0.2 to 2.0 μm, and even more preferably 0.3 to 1.0 μm. Here, the surface roughness Rsk is a parameter in the height direction (depth direction) of the surface unevenness, and represents the skewness of the roughness curve in the reference length. In other words, this can be understood as representing the symmetry of the convex and concave parts when the average line is the center. The larger the absolute value of the surface roughness Rsk, the smaller the surface reflectance and surface glossiness, and the smaller the specular glossiness on the wide angle side tends to be.

The above-mentioned surface roughnesses Ra, Rz, RSm, and Rsk refer to values measured and calculated in accordance with JIS standards (JIS B 0601-2001 and JIS B 0651-2001). Specifically, they can be measured using a three-dimensional surface roughness meter such as a stylus-type surface roughness measuring instrument (SURFCOM 1500SD2-3DF: Tokyo Seimitsu Co., Ltd.) based on "Geometric Properties of Products Specifications (GPS)-Surface Texture: Profile Curve Method-Terminology, Definitions, and Surface Texture Parameters, JIS B 0601:2001", and the surface roughness RSm, etc. can be calculated using the attached analysis software or general-purpose analysis software as necessary. More detailed measurement conditions are as follows.
Measurement length: 4.0 mm
Cutoff wavelength: 0.8 mm
Measurement speed: 0.6mm/s
Stylus: Single crystal diamond cone-shaped tip with a 2 μm radius and 60° apex angle

In addition, the surface glossiness of the surface 21a side of the low-reflection light-shielding layer laminate 100 (low-reflection light-shielding layer 21) of this embodiment can be appropriately set according to the required performance and is not particularly limited. From the viewpoint of achieving higher matteness and low surface glossiness, the 60-degree specular glossiness (JIS-Z8741:1997) of the surface 21a side of the low-reflection light-shielding layer laminate 100 (low-reflection light-shielding layer 21) is preferably 0.0% or more and less than 1.0%, more preferably 0.0% or more and less than 0.5%, even more preferably 0.0% or more and less than 0.4%, and particularly preferably 0.0% or more and less than 0.3%. Similarly, the 45 degree specular gloss (JIS-Z8741:1997) of the surface 21a side of the low reflection light-shielding layer laminate 100 (low reflection light-shielding layer 21) is preferably 0.0% or more and less than 1.0%, more preferably 0.0% or more and less than 0.5%, even more preferably 0.0% or more and less than 0.4%, and particularly preferably 0.0% or more and less than 0.3%. Similarly, the 20 degree specular gloss (JIS-Z8741:1997) of the surface 21a side of the low reflection light-shielding layer laminate 100 (low reflection light-shielding layer 21) is preferably 0.0% or more and less than 0.5%, more preferably 0.0% or more and less than 0.3%, even more preferably 0.0% or more and less than 0.2%, and particularly preferably 0.0% or more and less than 0.1%. In this specification, specular gloss refers to the value obtained by measuring the gloss (specular gloss) (%) of the surface 21a side of the low-reflection light-shielding layer laminate 100 (low-reflection light-shielding layer 21) at the specified incident and receiving angles (45°, 60°) using a digital variable-angle glossmeter (Gloss Meter VG7000: Nippon Denshoku Co., Ltd.) in accordance with JIS-Z8741:1997.

From the viewpoint of providing high light-shielding properties as a light-shielding member, the optical density (OD) of the entire low-reflection light-shielding layer laminate 100 is preferably 1.5 or more, more preferably 2.0 or more, even more preferably 2.5 or more, particularly preferably 3.0 or more, and most preferably 4.0 or more. Needless to say, the upper limit of the optical density (OD) is 6.0.

(Modification)
The present invention can be modified as desired within the scope of the present invention. In the first embodiment, the low-reflection light-shielding layer laminate 100 having a laminated structure in which the low-reflection light-shielding layer 21 is provided on the substrate 11 is shown, but the present invention can also be implemented in an embodiment in which the substrate 11 and the adhesive layer 31 are omitted. For example, the low-reflection light-shielding layer 21 can be peeled off from the substrate 11 described above to form a low-reflection light-shielding layer having a single-layer structure consisting of only the low-reflection light-shielding layer 21. Similarly, the present invention can be implemented as a low-reflection light-shielding layer laminate having a two-layer laminated structure in which the low-reflection light-shielding layer 21 is provided on the substrate 11 without providing the adhesive layer 31. Furthermore, in the first embodiment, the embodiment in which only one low-reflection light-shielding layer 21 is provided on the substrate 11 is shown, but the present invention can also be implemented in an embodiment in which the low-reflection light-shielding layer 21 is provided on one main surface 11a side and the other surface 11b side of the substrate 11. A conductive layer may be provided between the substrate 11 and the low-reflection light-shielding layer 21.

The present invention will be described in detail below with reference to examples and comparative examples, but the present invention is not limited to these examples. The present invention can adopt various conditions as long as the object of the present invention is achieved without departing from the gist of the present invention. In the following, "parts" refers to "parts by mass" unless otherwise specified.

Example 1
The following resin composition prepared in the mass ratio shown in Table 1 was applied by a bar coating method to one side of a 50 μm-thick biaxially stretched PET film (total light transmittance (550 nm): 89.1%) used as a substrate, and dried to form a low-reflection light-shielding layer shown in Table 2 on the substrate, thereby producing the low-reflection light-shielding layer and low-reflection light-shielding layer laminate of Example 1.

<Coating solution for resin layer>
Binder resin (isocyanate-curing acrylic resin, resin solid content: 25% by mass)
Coloring material (carbon black resin dispersion, average particle diameter _D50 : 25 nm)
Resin particles (black acrylic beads, average particle diameter _D50 : 4.0 μm)
Resin hardener (polyisocyanate hardener, solid content: 60% by mass)
Leveling agent (silicone-based, solid content: 10% by weight)
Dispersion medium 100 parts by mass (MEK: toluene = 50: 50 mixed solvent)

(Examples 2 to 3)
The low-reflection light-shielding layer and low-reflection light-shielding layer laminate of Examples 2 and 3 were prepared by forming a low-reflection light-shielding layer described in Table 2 on a substrate in the same manner as in Example 1, except for changing the mass ratio of each component as shown in Table 1.

(Comparative Example 1)
As shown in Table 1, a low-reflection light-shielding layer and a low-reflection light-shielding layer laminate of Comparative Example 1 were produced in the same manner as in Example 1, except that the amount of the resin particles used was changed.

(Comparative Example 2)
As shown in Table 1, a low-reflection light-shielding layer and a low-reflection light-shielding layer laminate of Comparative Example 2 were prepared in the same manner as in Example 1, except that amorphous silica having an average particle diameter _D50 of 9.5 μm was used instead of the resin particles and the mass ratio of each component was changed.

The physical properties of the low-reflection light-shielding layer laminates (low-reflection light-shielding layers) obtained in Examples 1 to 3 and Comparative Examples 1 and 2 were measured and evaluated under the following conditions. The evaluation results are also shown in Table 1.

(1) Surface roughness Ra, Rz, RSm, and Rsk
According to the measurement method of arithmetic mean roughness (Ra) of JIS-B0601 (2001), the surface roughnesses Ra, Rz, RSm, and Rsk (unit: μm) of the surface of the light-shielding layer were measured using a stylus surface roughness measuring instrument (SURFCOM 1500SD2-3DF: Tokyo Seimitsu Co., Ltd.).

(2) 550 nm Reflectance and 905 nm Reflectance Using a spectrophotometer (e.g., SolidSpec-3700 (manufactured by Shimadzu Corporation)), the diffuse reflectance (including regular reflection) (%) of the surface of the light-shielding layer was measured when light of wavelengths of 550 nm and 905 nm was incident on the surface.

(3) L ^*
Using a spectrophotometer (for example, ZE6000 (manufactured by Nippon Denshoku Industries Co., Ltd.)), L ^* of the surface of the light-shielding layer was measured in accordance with JIS Z 8720:2012 using CIE standard illuminant D ₆₅ .

(4) Specular Gloss In accordance with JIS-Z8741:1997, the surface gloss (specular gloss) (%) of the surface of the light-shielding layer was measured at each of the specified incident and receiving angles (20°, 45°, 60°) using a digital variable angle glossmeter (Gloss Meter VG7000: Nippon Denshoku Industries Co., Ltd.).

(5) Optical density OD
The optical density of the first resin layer 21 was measured using an optical densitometer (X-Rite 361T: X-Rite Corporation) based on ISO 5-2. An ortho filter was used during the measurement.

The present invention can be widely and effectively used as a low-reflection light-shielding member in applications that require low surface reflectance and a dark appearance, such as in the fields of precision machinery, semiconductors, optical equipment, in-vehicle applications, and theater rooms. In particular, the present invention can be effectively used as a light-shielding member (e.g., light-shielding plate or light-shielding ring) or a sliding member (e.g., shutter or aperture member) for various optical devices such as high-performance single-lens reflex cameras, compact cameras, video cameras, mobile phones, smartphones, PDA information terminals, and projectors.

100: Low-reflection light-shielding layer laminate 11: Substrate 11a: Surface (main surface)
11b... surface (principal surface)
21...Low reflection light shielding layer 21a...Surface 31...Adhesive layer

Claims (14)

Contains at least a binder resin, a colorant, resin particles, and a dispersion medium;
The content of the binder resin is 1 to 30 mass% in total based on the total amount of the binder resin in terms of solid content,
The content of the coloring material is 3 to 35% by mass in total based on the total amount of the solid content,
The content of the resin particles is 85 to 95% by mass in total based on the total amount of the solid content.
Resin composition for low reflection light shielding layer. 2. The resin composition for a low reflection light-shielding layer according to claim 1, wherein the resin particles have an average particle diameter D ₅₀ of 3 to 20 μm. 3. The resin composition for a low reflection light-shielding layer according to claim 1, wherein the resin particles contain colored resin particles. The ink-jet printhead comprises at least a binder resin, a colorant dispersed in the binder resin, and resin particles dispersed in the binder resin;
The content of the binder resin is 1 to 30 mass% in total in terms of solid content relative to the total amount of solid content,
The content of the coloring agent is 0.1 to 35 mass% in total in terms of solid content relative to the total amount of solid content,
The content of the resin particles is 85 to 95 mass% in total in terms of solid content with respect to the total amount of solid content,
The surface roughness Ra of one surface side is 0.2 to 0.7 μm.
Low-reflective light-shielding layer. The low reflection light-shielding layer according to claim 4 , wherein the resin particles contain colored resin particles. 6. The low reflection light-shielding layer according to claim 4, wherein the resin particles have an average particle size D ₅₀ of 3 to 20 μm. 7. The low reflection light-shielding layer according to claim 4, wherein one surface side has a surface roughness Rz of 2.0 to 5.0 μm. 8. The low reflection light-shielding layer according to claim 4, wherein the diffuse reflectance (including regular reflection) at 550 nm on one surface side is 0.0% or more and less than 3.0%. 9. The low reflection light-shielding layer according to claim 4, wherein the diffuse reflectance (including regular reflection) at 905 nm on one surface side is 0.0% or more and less than 3.0%. 10. The low reflection light-shielding layer according to claim 4, wherein one surface side of the low reflection light-shielding layer has an L ^* value of 0 to 18 in the CIE 1976 L ^* a ^* b ^* color system. The low-reflection light-shielding layer according to any one of claims 4 to 10, having an optical density OD of 0.5 or more. The low-reflection light-shielding layer according to any one of claims 4 to 11, having a thickness of 1 to 30 µm. A substrate;
A low-reflection light-shielding layer laminate comprising the low-reflection light-shielding layer according to any one of claims 4 to 12 provided on at least one main surface side of the substrate. A base film;
The low-reflection light-shielding layer according to any one of claims 4 to 12, which is provided on one main surface side of the base film;
The low-reflection light-shielding layer according to any one of claims 4 to 12, which is provided on the other main surface side of the base film;
A low-reflection light-shielding layer laminate comprising: