Ink for forming low-reflection layer, low-reflectivity laminate, and method for forming low-reflection layer

Abstract

The present disclosure provides: an ink for forming a low-reflection layer, the ink containing a binder resin, a colorant, microparticles, and an organic solvent for forming a low-reflection layer with excellent light shielding properties, low-reflectivity, substrate adhesiveness, scratch resistance, and heat and moisture resistance; a low-reflectivity laminate using the ink; and a method for forming the low-reflection layer.

Description

[Technical Field]

[0001] The present disclosure relates to an ink for forming a low-reflection layer, a low-reflection laminate, and a method for forming a low-reflection layer.

[0002] More specifically, the present invention relates to an ink for forming a low-reflection layer, a low-reflection laminate having a low-reflection layer on a substrate and having excellent low reflectivity and light-shielding properties on the surface of the low-reflection layer, and a method for forming a low-reflection layer. [Background technology]

[0003] In the imaging field, low-reflectivity black ink is applied to the sides and edges of lenses in camera modules for SLR cameras, smartphones, and other devices to remove unnecessary incident and reflected light and suppress the occurrence of flares and ghosts that degrade image quality. Meanwhile, in the sensing field, there is increasing demand for ToF (Time of Flight) sensors that use laser light to measure distance for the purposes of object recognition and 3D measurement. For these ToF sensors, low-reflectivity paint is applied around the light source to suppress internal reflections of the laser light source.

[0004] Outside of the imaging and sensing fields, low-reflectivity colored inks are expected to add design value to packaging for consumer goods. With the increased demand for online video shooting amid the COVID-19 pandemic, low-reflectivity materials are also required for green screens used as backgrounds for subjects to improve image quality.

[0005] For the optical applications of imaging and sensing, there is an example of a surface anti-reflective coating film that uses a surface anti-reflective coating for atomization application containing a binder resin, carbon black, hydrophobically treated dry silica, roughening particles, dye, and solvent (Patent Document 1). However, while this method imparts black color by using carbon black in combination with a dye, there is a concern that the low reflectivity will deteriorate over time due to the dye's poor light resistance. Furthermore, this composition is for atomization application, and is not a printing ink. Even if it is applied to, for example, a screen printing ink, it is thought that the effect of forming unevenness is small, making it difficult to achieve low reflectivity. Furthermore, the amount of silica used as a matting agent is excessive, which may result in poor scratch resistance and reverse gloss.

[0006] Patent Documents 2 and 3 describe a low-reflection film using carbon black, an optical sensing kit using the same, and a low-reflection molded body. However, the average particle diameter (D50) of the colorant carbon black is small at 25 nm, and it has high transmittance in the visible light region, so there is a concern that the light-blocking properties may be insufficient. In addition, the content of the acrylic resin binder resin is low, which causes problems with adhesion to the substrate. Therefore, a technology that satisfies the characteristics of a low-reflection laminate has not yet been obtained. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Publication No. 2020-97730 [Patent Document 2] WO2020 / 195693 [Patent Document 3] Japanese Patent Publication No. 2021-140072 Summary of the Invention [Problem to be solved by the invention]

[0008] An object of the present disclosure is to provide an ink for forming a low-reflection layer that is excellent in light-blocking properties and low reflectivity, as well as in substrate adhesion, scratch resistance, and moist heat resistance, a low-reflection laminate, and a method for forming a low-reflection layer. [Means for solving the problem]

[0009] As a result of extensive research, the present inventors have found that the above-mentioned problems can be solved by the following invention, and have thus completed the present invention.

[0010] The present disclosure relates to an ink for forming a low-reflection layer, which contains a binder resin, a colorant, fine particles (excluding the colorant), and an organic solvent, wherein the content of the binder resin is more than 30 mass % and not more than 55 mass % of the total mass of the ink solids, the average particle diameter of the colorant is 50 to 250 nm, and the fine particles include an extender pigment and / or resin fine particles.

[0011] The present disclosure also relates to the ink for forming a low-reflection layer, wherein the binder resin comprises at least one resin selected from the group consisting of an acrylic resin, a polyester resin, and a urethane resin.

[0012] The present disclosure also relates to the ink for forming a low-reflection layer, wherein the colorant contains at least carbon black.

[0013] The present disclosure also relates to the ink for forming a low reflective layer, wherein the binder resin has a hydroxyl value of 10 to 50 mgKOH / g.

[0014] The present disclosure also relates to the ink for forming a low reflection layer, wherein the total mass of the colorant and the fine particles is 40 to 55 mass % of the total mass of the ink solids.

[0015] The present disclosure also relates to the ink for forming a low reflection layer, wherein the fine particles have an average particle size of 0.5 to 15 μm.

[0016] The present disclosure also relates to the ink for forming a low reflection layer, wherein the fine particles are resin fine particles, and the resin fine particles include at least one selected from the group consisting of polyester resin fine particles and acrylic resin fine particles.

[0017] The present disclosure also relates to the ink for forming a low reflection layer, wherein the mass ratio of the colorant to the fine particles (fine particles / colorant) is in the range of 3-5.

[0018] The present disclosure also relates to the ink for forming a low-reflection layer, wherein the organic solvent comprises an organic solvent (A) consisting of a ketone-based organic solvent, and at least one organic solvent (B) selected from glycol ether-based organic solvents, ester-based organic solvents, aliphatic organic solvents, and aromatic organic solvents.

[0019] The present disclosure also relates to the ink for forming a low reflective layer, wherein the difference in boiling point between the organic solvent (A) and the organic solvent (B) is 35 to 80°C.

[0020] The present disclosure also relates to a low-reflection laminate having, on a substrate, a low-reflection layer made from the ink for forming a low-reflection layer.

[0021] The present disclosure also relates to a method for forming a low-reflection layer, which includes printing a low-reflection layer-forming ink on a substrate to form a low-reflection layer, wherein the ink is the low-reflection layer-forming ink described above, and the method includes a drying step of volatilizing the organic solvent. [Effects of the Invention]

[0022] The present disclosure makes it possible to provide an ink for forming a low-reflection layer that is excellent in light-blocking properties and low reflectivity, as well as in substrate adhesion, scratch resistance, and moist heat resistance, a low-reflection laminate, and a method for forming a low-reflection layer. DETAILED DESCRIPTION OF THE INVENTION

[0023] The following describes in detail the embodiments of the present invention. However, the description of the constituent elements described below is an example (representative example) of an embodiment of the present invention, and the present invention is not limited to these contents as long as it does not exceed the gist of the present invention.

[0024] In the present disclosure, "low reflection" is synonymous with "anti-reflection" described in the prior art, and refers to a reflectivity lower than that of a layer before improvement. Note that, hereinafter, the "low-reflection laminate" may be simply referred to as the "laminate," and the "ink for forming a low-reflection layer" may be simply referred to as the "printing ink" or "ink," but they have the same meaning.

[0025] The present disclosure will be described in detail below. The present disclosure relates to an ink for forming a low-reflection layer, which contains a binder resin, a colorant, fine particles, and an organic solvent, wherein the content of the binder resin is more than 30% by mass and not more than 55% by mass of the total mass of the ink solids, the average particle diameter of the colorant is 50 to 250 nm, and the fine particles include an extender pigment and / or resin fine particles. By setting the binder resin content in the ink within the above range, the ink layer formed after drying has the effect of improving substrate adhesion, scratch resistance, and moist heat resistance.Furthermore, by setting the average particle size of the colorant within the above range, the ink maintains good fluidity while improving light-blocking properties and low reflectivity.This results in the ink layer formed having low reflectivity and further satisfying light-blocking properties, substrate adhesion, scratch resistance, and moist heat resistance.The use of a low-reflection laminate including a low-reflection layer made from the ink for forming a low-reflection layer of the present disclosure inside the lens barrel or around the image sensor of a camera module for a smartphone or an in-vehicle sensor can contribute to suppressing phenomena such as ghosting and flare.However, this function is based on speculation and does not particularly limit the present disclosure.

[0026] <Ink for forming low-reflection layer> The ink for forming a low-reflection layer of the present disclosure contains a binder resin, a colorant, fine particles, and an organic solvent. A low-reflection layer can be formed by printing the ink for forming a low-reflection layer on a substrate and drying it, and the resulting printed matter becomes a low-reflection laminate.

[0027] (binder resin) In the present disclosure, the binder resin refers to a resin that can function as a binding agent in the ink, and is preferably a thermoplastic resin. Examples of thermoplastic resins include acrylic resins, polyester resins, urethane resins, vinyl chloride-vinyl acetate copolymer resins, epoxy resins, styrene-based resins, rosin-based resins, styrene-maleic acid resins, dammar resins, polycarbonate resins, rosin-modified maleic acid resins, rosin ester resins, and terpene resins, and these resins may be used in combination within a range that does not impair the effects of the present disclosure. From the viewpoint of substrate adhesion and moist heat resistance, it is preferable that the thermoplastic resin contains at least one selected from the group consisting of acrylic resin, polyester resin, and urethane resin, and it is more preferable that the thermoplastic resin contains acrylic resin.

[0028] Since the binder resin provides adhesion of the ink layer to the substrate, it is advisable to appropriately control the content of the binder resin in the ink. On the other hand, if the content of the binder resin in the ink is excessive, the unevenness of the surface of the low-reflection layer is likely to be flattened, which may result in a decrease in low reflectivity. In the present disclosure, in order to improve the low reflectivity of the low-reflection layer, the average particle size of the colorant in the ink for forming the low-reflection layer and the content of the binder resin in the ink are appropriately controlled. Flexible binder resins such as urethane resins provide good adhesion of the ink layer to the substrate, but lack sufficient environmental resistance, and deterioration over time may be a concern in more adverse environments. Acrylic resins are binder resins that have excellent environmental resistance and scratch resistance, but they tend to have slightly poorer adhesion to the substrate and are less likely to form uneven surfaces. In the present disclosure, by appropriately controlling the average particle size of the colorant and the content of the binder resin in the ink, even when an acrylic resin is used, it is possible to appropriately form an uneven surface shape and obtain good low reflectivity while obtaining sufficient adhesion to the substrate. Furthermore, as will be described later, by controlling the composition of the organic solvent contained in the ink, the uneven surface shape of the low-reflectivity layer can be more appropriately formed in the process of forming the ink layer, making it possible to further improve low reflectivity.

[0029] Furthermore, in the present disclosure, it is preferable to appropriately control the amount of hydroxyl groups in the binder resin in order to provide adhesion of the ink layer to the substrate. By appropriately controlling the average particle size of the colorant and the content of the binder resin in the ink, it is possible to suppress a decrease in low reflectivity even when the amount of hydroxyl groups in the binder resin is set within a range suitable for adhesion to the substrate.

[0030] The content of the binder resin is in the range of more than 30% by mass and not more than 55% by mass, more preferably in the range of 32 to 55% by mass, and even more preferably in the range of 35 to 50% by mass, based on the total mass of the ink solids. By making it more than 30% by mass, substrate adhesion, scratch resistance, and moist heat resistance are improved, and by making it not more than 55% by mass, light blocking properties and low reflectivity are improved.

[0031] The hydroxyl value of the binder resin is preferably in the range of 10 to 50 mgKOH / g, and more preferably in the range of 20 to 40 mgKOH / g. A hydroxyl value of 10 mgKOH / g or more provides good adhesion to substrates, while a hydroxyl value of 50 mgKOH / g or less provides good moist heat resistance. In the present disclosure, the hydroxyl value of the binder resin is the amount of hydroxyl groups per 1 g of resin calculated by esterifying or acetylating the hydroxyl groups in the resin and back-titrating the remaining acid with an alkali, converted into mg of potassium hydroxide, and measured in accordance with JIS K0070.

[0032] The weight average molecular weight (Mw) of the binder resin may be 1,000 to 200,000, 2,000 to 180,000, or 3,000 to 170,000, preferably in the range of 5,000 to 120,000, and more preferably in the range of 20,000 to 100,000. By making the weight average molecular weight 5,000 or more, printability is improved, and by making it 120,000 or less, scratch resistance is improved. The weight average molecular weight is determined by GPC (gel permeation chromatography). Permeation The polystyrene equivalent value is measured by chromatography. When the binder resin is an acrylic resin, the weight average molecular weight (Mw) of the acrylic resin is preferably 30,000 to 80,000, 35,000 to 60,000, or 40,000 to 50,000 from the viewpoints of substrate adhesion and low reflectivity.

[0033] (coloring agent) Examples of colorants used in the present disclosure include various organic pigments, inorganic pigments, dyes, and the like, which can be used in combination within a range that does not impair the effects of the present disclosure. However, from the viewpoint of light-blocking properties and low reflectivity, it is preferable to use carbon black. The average particle size of the colorant used in the present disclosure is in the range of 50 to 250 nm, and more preferably in the range of 100 to 200 nm. A particle size of 50 nm or more improves the fluidity of the ink, while a particle size of 250 nm or less improves the light-blocking properties and low reflectivity.

[0034] The average particle size in the present disclosure refers to the D50 particle size of the volume integrated value measured by dynamic light scattering, and can be measured, for example, using a Microtrac (manufactured by Microtrac-Bell, product name "MT3300EXII"). A measurement sample may be prepared appropriately depending on the measurement device, and for example, a particle dispersion is prepared by diluting 100 times by weight with a measurement solvent.

[0035] (carbon black) The carbon black used in the present disclosure may be any known carbon black, and examples thereof include CI Pigment Black 7, as indicated by the CI number of the Colour Index International (abbreviated as CI).

[0036] The oil absorption of the above carbon black is 10 to 150 cm 3 / 100g, and 20 to 100cm 3 It is more preferable that the oil absorption is in the range of / 100g. By setting the oil absorption in this range, sufficient density of the printed matter can be obtained and light blocking properties will be good. The oil absorption is measured in accordance with JIS K6221, and is the amount of DBP (dibutyl phthalate) absorbed by 100g of carbon black.

[0037] The specific surface area of ​​carbon black (nitrogen adsorption method) is 5 to 200 m 2 / g, and 10 to 150m 2 By setting the specific surface area in this range, printability becomes good.

[0038] Specific examples of carbon black that meets the above requirements include Mitsubishi Carbon #10, Mitsubishi Carbon #20, Mitsubishi Carbon MA220 (manufactured by Mitsubishi Chemical Corporation), Seast S, Seast SP, Seast TA (manufactured by Tokai Carbon Co., Ltd.), SUNBLACK235, Asahi #8, and Asahi #15 (manufactured by Asahi Carbon Co., Ltd.).

[0039] Specific examples of organic pigments other than the above carbon black that can be preferably used as colorants are shown below by color index numbers.

[0040] Yellow pigments include CI Pigment Yellow 1, 2, 3, 4, 5, 6, 10, 12, 13, 14, 15, 16, 17, 18, 20, 24, 31, 32, 34, 35, 35:1, 36, 36:1, 37, 37:1, 40, 42, 43, 53, 55, 60, 61, 62, 63, 65, 73, 74, 77, 81, 83, 86, 93, 94, 95, 97, 98, 100, 101, 104, 106, 108, 109, 110, 113, 114, 115, 116, 117, 118, 119, 120, 123, 125, 126, 127, 128, 129, 130, 131, 132, 133, 134, 135, 136, 137, 138, 139, 140, 141, 142, 143, 144, 145, 146, 147, 148, 149, 150, 151, 152, 153, 154, 155, 156, 157, 158, 159, 160, 161, 162, 163, 164, 165, 166, 167, 168, 169, 170, 171, 1 6, 127, 128, 129, 137, 138, 139, 147, 148, 150, 151, 152, 153, 154, 155, 156, 161, 162, 164, 166, 167, 168, 169, 170, 171, 172, 173, 174, 175, 176, 177, 179, 180, 181, 182, 185, 187, 188, 193, 194, 198, 199, 213, 214, 218, 219, 220, 221, 231, etc. can be suitably used.

[0041] Crimson pigments include CI Pigment Red 7, 9, 14, 41, 48:1, 48:2, 48:3, 48:4, 57:1, 81, 81:1, 81:2, 81:3, 81:4, 97, 122, 123, 146, 149, 150, 168, 169, 176, 177, 178, 180, 184, 185, 187, 192, 200, 202, 208, 209, 210, 215, 216, 217, 220, 223, 224, 226, 227, 228, 240, 242, 246, 254, 255, 264, 268, 270, 272, 273, 274, 276, 277, 278, 279, 280, 281, 282, 283, 284, 285, 286, 287, etc. can be suitably used.

[0042] As the indigo pigment, CI Pigment Blue 1, 1:2, 1:3, 2, 2:1, 2:2, 3, 8, 9, 10, 10:1, 11, 12, 15, 15:1, 15:2, 15:3, 15:4, 15:6, 16, 18, 19, 22, 24, 24:1, 53, 56, 56:1, 57, 58, 59, 60, 61, 62, 64, etc. can be suitably used.

[0043] As the orange pigment, CI Pigment Orange 36, 38, 43, 51, 55, 59, 61, 71, 73, etc. can be suitably used.

[0044] As the green pigment, CI Pigment Green 7, 10, 36, 37, 58, 62, 63, etc. can be suitably used.

[0045] As the purple pigment, CI Pigment Violet 1, 19, 27, 29, 30, 32, 37, 40, 42, 50, etc. can be suitably used.

[0046] Examples of inorganic pigments include titanium oxide, aluminum paste, mica, bronze powder, chrome vermilion, yellow lead, cadmium yellow, cadmium red, ultramarine, Prussian blue, red iron oxide, yellow iron oxide, iron black, etc. In order to ensure good coatability, sensitivity, developability, etc. while maintaining a balance between saturation and brightness, inorganic pigments are also preferably used in combination with organic pigments.

[0047] The colorant content is preferably in the range of 5 to 15% by mass, more preferably 7 to 12% by mass, of the total mass of the ink solids. When the content is 5% by mass or more, good light-blocking properties are achieved, and when the content is 15% by mass or less, good substrate adhesion and scratch resistance are achieved.

[0048] (fine particles) The ink for forming a low-reflection layer of the present disclosure contains an extender pigment and / or resin fine particles as the fine particles. From the viewpoint of low reflectivity and printability, it is preferable to use resin fine particles as the fine particles. Note that the fine particles do not include so-called color pigments or colored resin fine particles, which are colorants. However, this does not exclude cases where the extender pigment and / or resin fine particles are slightly colored.

[0049] The average particle size of the fine particles is preferably in the range of 0.5 to 15 μm, more preferably in the range of 2 to 10 μm. By making the average particle size 0.5 μm or more, fine irregularities can be formed on the surface of the low-reflection layer, resulting in good low reflectivity, and by making it 15 μm or less, the scratch resistance of the surface of the low-reflection layer can be good.

[0050] The refractive index of the fine particles used in the present disclosure is preferably in the range of 1.4 to 1.6, and more preferably in the range of 1.45 to 1.5. By setting the refractive index within the above range, the low reflectivity becomes better.

[0051] The content of the fine particles is preferably in the range of 25 to 50% by mass, more preferably 35 to 45% by mass, of the total mass of the ink solids. A content of 25% by mass or more improves low reflectivity, while a content of 50% by mass or less improves scratch resistance.

[0052] Examples of extender pigments that can be used include, but are not limited to, one or more of silica fine particles, alumina fine particles, talc fine particles, calcium carbonate fine particles, kaolin fine particles, precipitated barium sulfate fine particles, and the like.

[0053] Examples of resin particles include polyester resin particles, acrylic resin particles, melamine resin particles, melamine-benzoguanamine resin particles, benzoguanamine-formaldehyde condensed resin particles, fluororesin particles, urethane resin particles, and cellulose resin particles, among which polyester resin particles and / or acrylic particles are preferred, and polyester resin particles are more preferred. However, one or more types may be used, and the resin particles applicable to the present disclosure are not limited to these.

[0054] Examples of polyester resin particles include polyester resin particles made of polyhydroxyalkanoic acid, polyester resin particles made of a condensate of dibasic acid and diol, and polylactic acid resin particles. Among these, polyester resin particles made of polyhydroxyalkanoic acid and polyester resin particles made of a condensate of dibasic acid and diol are particularly preferred. Child The polyester resin particles are preferably polyester resin particles made of polyhydroxyalkanoic acid, and more preferably polyester resin particles made of biodegradable resin.

[0055] Specific examples of polyester resin microparticles include Techpolymer TP-MG series (manufactured by Sekisui Plastics Co., Ltd.). resin Examples of methods for producing particles include those described in JP-A Nos. 2007-191617 and 5-194141.

[0056] Specific examples of acrylic resin microparticles include Eposter MA1002, Eposter MA1004, Eposter MA1006, Eposter MA1010 (manufactured by Nippon Shokubai Co., Ltd.), Tuftic FH-S005, Tuftic FH-S008, Tuftic FH-S010, Tuftic FH-S015, Tuftic FH-S020 (manufactured by Toyobo Co., Ltd.), Chemisnow MX-80H3wT, MX-150, MX-180TA, MX-300, MX-500, MX-1000, MX-1500H, MX-2000, MX-3000 (manufactured by Soken Chemical & Engineering Co., Ltd.), and the like.

[0057] Specific examples of melamine resin fine particles include Eposter SS, Eposter S, Eposter FS, Eposter S6, and Eposter S12 (manufactured by Nippon Shokubai Co., Ltd.). A specific example of melamine-benzoguanamine resin microparticles is Eposter M30 (manufactured by Nippon Shokubai Co., Ltd.).

[0058] Specific examples of benzoguanamine-formaldehyde condensation resin microparticles include Eposter MS and Eposter L15 (manufactured by Nippon Shokubai Co., Ltd.). 。

[0059] Specific examples of fluororesin particles include KTL-1N, KTL-2N, KTL-8N (manufactured by Kitamura Co., Ltd.), Shamrock SST-3D, Shamrock SST-4MG (manufactured by Shamrock Technologies), and the like.

[0060] Specific examples of urethane microparticles include crosslinked urethane beads such as Art Pearl C-1000 transparent, Art Pearl C-600 transparent, Art Pearl C-400 transparent, Art Pearl C-800, Art Pearl MM-120T, Art Pearl JB-800T, Art Pearl JB-600T, Art Pearl P-800T, and Art Pearl P-400T (manufactured by Negami Chemical Industrial Co., Ltd.).

[0061] In the present disclosure, the total amount of colorant and fine particles is preferably in the range of 40 to 55% by mass, more preferably 45 to 50% by mass, of the total mass of the ink solids. A content of 40% by mass or more improves light blocking properties and low reflectivity, while a content of 55% by mass or less improves substrate adhesion, scratch resistance, and moist heat resistance.

[0062] In the present disclosure, the ratio of colorant to fine particles (fine particles / colorant) in the low-reflection layer is preferably in the range of 3 to 5, more preferably in the range of 3.5 to 5, and even more preferably in the range of 4 to 4.8. When the ratio is 3 or more, good low reflectivity is achieved, and when it is 5 or less, good light-blocking properties are achieved.

[0063] (organic solvent) The printing ink preferably contains an organic solvent. Examples of the organic solvent include glycol ether organic solvents, ester organic solvents, aliphatic organic solvents, aromatic organic solvents, alcohol organic solvents, and ketone organic solvents. Among these, the printing ink preferably contains an organic solvent (A) consisting of a ketone organic solvent and at least one organic solvent (B) selected from glycol ether organic solvents, ester organic solvents, aliphatic organic solvents, and aromatic organic solvents. More preferably, a ketone organic solvent, which has good solubility for the binder resin, and a glycol ether organic solvent or an ester organic solvent, which has good printability, are used.

[0064] It is preferable to use two or more organic solvents in combination. The two or more organic solvents preferably have different boiling points. By using organic solvents with different boiling points, the low-boiling solvent volatilizes on the substrate surface, followed by the high-boiling solvent, resulting in a difference in drying speed. This difference in drying speed allows the resulting low-reflection layer to have more appropriate low reflectivity. Although not limited to the reason, it is believed that on the substrate surface, while the low-boiling solvent volatilizes, the fine particles aggregate appropriately, and then while the high-boiling solvent volatilizes, the fine particles remain in an appropriately aggregated state, causing the fine particles to segregate on the surface of the low-reflection layer, resulting in the uneven shape of the surface of the low-reflection layer being suitable for low reflectivity.

[0065] In a low-reflection layer, surface roughness Ra is one index of low reflectivity. When two or more organic solvents with different boiling points are used, the uneven shape of the surface of the low-reflection layer can be made suitable for low reflectivity, as described above. In this case, for example, the low-reflection layer obtained using the ink for forming a low-reflection layer preferably has a surface roughness Ra of 3 to 5 μm.

[0066] When organic solvents (A) and (B) are used, it is preferable that the boiling point of organic solvent (A) is higher than that of organic solvent (B). On the substrate surface, the organic solvent (B), which has a lower boiling point, volatilizes first, followed by organic solvent (A). In this case, since the binder resin is easily soluble in organic solvent (A), after organic solvent (B) volatilizes on the substrate surface, the binder resin dissolved in organic solvent (A) encapsulates the colorant and fine particles, allowing the colorant and fine particles to be more uniformly fixed to the substrate surface. This results in the formation of an appropriate uneven shape on the surface of the low-reflection layer, enabling the low reflectivity of the low-reflection layer to be more appropriately adjusted. When organic solvents (A) and (B) are used in consideration of the difference in boiling points, the surface roughness Ra of the resulting low-reflection layer can be adjusted to a more appropriate range, for example, 3 to 5 μm.

[0067] (Organic solvent (A)) The organic solvent (A) is a ketone-based organic solvent. Ketone-based organic solvents can be classified into cyclic ketone-based organic solvents having a cyclic skeleton and ketone-based organic solvents not having a cyclic skeleton. Among them, it is preferable to use a cyclic ketone-based organic solvent from the viewpoint of printability. Furthermore, cyclic ketone-based organic solvents are preferred because they have a higher boiling point than other ketone-based solvents and are excellent in printability. Furthermore, cyclic ketone-based organic solvents are preferred because they can increase the boiling point difference with respect to the organic solvent (B), and the boiling point difference enhances the effect of forming unevenness in the low-reflection layer.

[0068] The cyclic ketone organic solvent is preferably an organic solvent containing a 5- to 7-membered cyclic ketone structure in the molecule. Examples of the 5-membered cyclic ketone organic solvent include cyclopentanone, 2-methyl-2-cyclopenten-1-one, 2-methylcyclopentanone, 3-methylcyclopentanone, 2-ethylcyclopentanone, 3-ethylcyclopentanone, 2,2-dimethylcyclopentanone, and 2,4,4-trimethylcyclopentanone. Examples of the 6-membered cyclic ketone organic solvent include cyclohexanone, isophorone, 2-cyclohexen-1-one, 2-methylcyclohexanone, 3-methylcyclohexanone, 4-methylcyclohexanone, 4-ethylcyclohexanone, 2,6-dimethylcyclohexanone, and 2,2-dimethylcyclohexanone. Examples of the seven-membered cyclic ketone organic solvent include cycloheptanone and 2-cycloheptan-1-one.

[0069] Examples of the ketone solvents not having a cyclic skeleton include acetone, methyl ethyl ketone, methyl isobutyl ketone, and diisobutyl ketone. The organic solvent (A) may be one kind or a combination of two or more kinds. In the case of a combination of two or more kinds, the organic solvent (A) is preferably a cyclic ketone organic solvent used alone, or may be a combination of a cyclic ketone organic solvent with another organic solvent (A).

[0070] The boiling point of the organic solvent (A) is preferably 100 to 270°C, more preferably 120 to 250°C, and even more preferably 140 to 230°C. Having a boiling point within this range improves printability and low reflectivity. When the organic solvent (A) contains a cyclic ketone organic solvent, the boiling point of the cyclic ketone organic solvent is preferably 150 to 270°C or 155 to 270°C, and more preferably 200 to 270°C or 210 to 270°C, from the viewpoint of ensuring the uneven shape of the low-reflection layer depending on the drying speed.

[0071] (Organic solvent (B)) In the present disclosure, the organic solvent (B) contains at least one selected from glycol ether-based organic solvents, ester-based organic solvents, aliphatic organic solvents, and aromatic organic solvents. Among these, from the viewpoint of printability, it is preferable to contain a glycol ether-based organic solvent or an ester-based organic solvent. However, the organic solvent (B) does not contain the organic solvent (A).

[0072] Examples of glycol ether organic solvents include ethylene glycol dibutyl ether, ethylene glycol monobutyl ether, ethylene glycol monohexyl ether, ethylene glycol monomethoxymethyl ether, diethylene glycol ethyl methyl ether, diethylene glycol dimethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, diethylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol monobutyl ether, dipropylene glycol monomethyl ether, triethylene glycol dimethyl ether, triethylene glycol monomethyl ether, tripropylene glycol monomethyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, and propylene glycol monobutyl ether.

[0073] Examples of ester-based organic solvents include gamma-butyrolactone, cellosolve acetate, propylene glycol monomethyl ether acetate, ethylene glycol diacetate, ethylene glycol monoacetate, ethylene glycol monobutyl ether acetate, diethylene glycol diacetate, diethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether acetate, and propylene carbonate.

[0074] Examples of the aliphatic organic solvent include normal paraffin solvents, isoparaffin solvents, and cycloparaffin solvents.

[0075] Aromatic organic solvents include toluene, xylene, ethylbenzene, naphthalene, tetralin, solvent naphtha, and aromatic sex Examples of solvents rich in hydroxybenzoates include Swazol (manufactured by Cosmo Oil Co., Ltd. and Maruzen Petrochemical Co., Ltd.), Solvesso (manufactured by Exxon Mobil Corp.), and Cactus Fine (manufactured by Japan Energy Corp.). The organic solvent (B) may be one type or a combination of two or more types. In the case of a combination of two or more types, it is preferable to use one of a glycol ether-based organic solvent and an ester-based organic solvent alone as the organic solvent (B), or one of a glycol ether-based organic solvent and an ester-based organic solvent may be combined with another organic solvent (B).

[0076] Organic solvent (B) tends to be compatible with organic solvent (A) and has a relatively low viscosity, which makes it possible to improve the coatability of an ink containing organic solvent (A) and a binder resin. When the boiling point of organic solvent (A) is higher than the boiling point of organic solvent (B), the ink containing organic solvent (A) and organic solvent (B) is uniformly coated on the surface of the substrate, and then organic solvent (B) is volatilized and removed, leaving behind the organic solvent (A) that was included in the ink. can This allows the binder resin, colorant, and fine particles to be fixed uniformly to the surface of the substrate.

[0077] The boiling point of the organic solvent (B) is preferably 100 to 270°C, more preferably 120 to 250°C. 、 It is more preferably 140 to 230°C. Within this range, printability and low reflectivity are improved. When the organic solvent (B) contains at least one of a glycol ether organic solvent and an ester organic solvent, the boiling points of the glycol ether organic solvent and the ester organic solvent are preferably 100 to 200°C, 100 to 180°C, 100 to 160°C, or 100 to 150°C, and more preferably 110 to 160°C, or 110 to 150°C, from the viewpoint of ensuring the uneven shape of the low reflectivity layer depending on the drying speed.

[0078] It is believed that if the boiling point of the organic solvent (B) is high, the drying rate on the substrate surface will be slower, potentially improving the coatability of the ink. It is also believed that a smaller difference in boiling point between the organic solvents (A) and (B) will synchronize the timing of the volatilization of multiple types of organic solvents, potentially improving the coatability of the ink. On the other hand, in the present disclosure, from the viewpoint of the low reflectivity of the low-reflection layer, in order to ensure an uneven shape on the surface of the low-reflection layer, it is preferable that the organic solvent (B) has a low boiling point, and it is preferable that the boiling point difference between the organic solvents (A) and (B) satisfies the following range:

[0079] In the present disclosure, the difference in boiling point between the organic solvent (A) and the organic solvent (B) is preferably 1°C or more, 5°C or more, 10°C or more, or 20°C or more. The difference in boiling point between the organic solvent (A) and the organic solvent (B) is preferably 35 to 80°C, more preferably in the range of 40 to 70°C. By using multiple organic solvents with a difference in boiling point within the above range, the organic solvents are gradually evaporated in the drying step, which makes it easier for fine particles to segregate on the surface of the low-reflection layer. As a result, an uneven shape can be more effectively formed on the surface of the low-reflection layer, improving low reflectivity. Furthermore, when printing the ink for forming the low reflection layer, it is preferable to dry it at a temperature of 80° C. or higher. A short drying time makes it possible to efficiently form the uneven shape.

[0080] The content of the organic solvent is preferably in the range of 35 to 80% by mass, and more preferably in the range of 40 to 70% by mass, relative to the total mass of the ink for forming a low reflection layer, because this improves the solubility of the resin. The organic solvent (A) and the organic solvent (B) can be blended in any ratio, but the mass ratio of organic solvent (A) / organic solvent (B) is preferably in the range of 90 / 10 to 50 / 50, and more preferably in the range of 80 / 20 to 55 / 45. Within these ranges, the surface irregularities of the low-reflection layer can be made more appropriate, and low reflectivity can be further improved.

[0081] (hardening agent) If necessary, the ink for forming the low-reflection layer may be appropriately blended with a polyisocyanate-type curing agent within a range that does not impair the object of the present disclosure.

[0082] The content of the curing agent is preferably such that the ratio NCO / OH, which is the ratio of the amount of available isocyanate in the curing agent to the hydroxyl groups in the binder resin in the ink solids, is in the range of 0.5 to 1.5, more preferably 0.75 to 1.25. By making the NCO / OH ratio 0.5 or more, substrate adhesion and scratch resistance are improved, and by making it 1.5 or less, moist heat resistance is improved.

[0083] (additives) The ink for forming the low-reflection layer may contain additives such as dispersants, antifoaming agents, leveling agents, wetting and penetrating agents, antiskinning agents, ultraviolet absorbers, antioxidants, crosslinking agents, preservatives, antifungal agents, viscosity adjusters, and pH adjusters, as needed, within a range that does not impair the object of the present disclosure.

[0084] <Production of ink for forming low-reflection layer> The ink for forming a low-reflection layer used in the present disclosure can be produced by mixing the required amounts of binder resin, colorant, fine particles, organic solvent, and, if necessary, curing agent and / or additives, and stirring thoroughly with a stirrer or the like, or by first preparing a dispersion containing colorant, dispersant, and organic solvent, and then mixing the required amounts of binder resin, organic solvent, curing agent, and / or additives, and stirring thoroughly with a stirrer or the like.

[0085] <Formation of low-reflection layer> In the present disclosure, printing methods for forming a low-reflection layer on a substrate include screen printing, roll coating, dispenser coating, dip coating, brush coating, etc., and among these, screen printing is preferred. As the printing machine, a cylinder press printing machine or a semi-automatic printing machine is used, and as the printing plate, a resin material such as nylon or polyester, stainless steel, etc. is used. Source of It is preferable to use materials.

[0086] <Screen printing> Screen printing is a technique that uses a screen made of synthetic fibers such as polyester or nylon, or a stainless steel screen, and then uses a photosensitive emulsion on the screen to pattern areas where the ink will pass through and areas where it will not, and then transfers the ink to the substrate by pressing and moving the ink against the inner surface of the screen with a spatula-shaped rubber plate called a squeegee.The angle of the weave direction of the mesh relative to the screen frame is called the bias angle.The thickness of the printed ink film can be adjusted by the film thickness of the photosensitive emulsion applied to the substrate surface. During printing, the angle between the substrate and the squeegee in the printing direction is called the attack angle. After printing, the ink can be fixed to the substrate by volatilizing the solvent in the ink using a hot air oven.

[0087] <Low reflective layer formation method> The present disclosure relates to a method for forming a low-reflection layer by printing a low-reflection layer-forming ink on a substrate to form a low-reflection layer, the ink containing a binder resin, a colorant, fine particles, and an organic solvent, the binder resin content being 30 to 55 mass% of the total mass of the ink solids, the colorant having an average particle diameter of 50 to 250 nm, and the method including a drying step of volatilizing the organic solvent. By setting the binder resin content and the average particle diameter of the colorant in the ink within the above ranges, the colorant dispersion stability is improved, making it possible to effectively segregate only the fine particles in the drying step. As a result, the segregated fine particles form an uneven shape on the surface of the low-reflection layer, allowing the formation of a low-reflection layer. Furthermore, the drying mechanism of the organic solvent described above makes it possible to more effectively segregate the fine particles.

[0088] As an index of the uneven shape formed by the fine particles segregated on the surface of the low-reflection layer, the surface roughness Ra of the low-reflection layer is preferably 3 to 5 μm, and more preferably 3.5 to 5 μm. A surface roughness Ra in the above range has the advantage of improving low reflectivity. The surface roughness Ra is the arithmetic mean roughness, and is a value measured in accordance with the JIS B0601:2001 method using a shape analysis laser microscope.

[0089] In the low-reflectivity laminate of the present disclosure, a low-reflectivity layer is preferably formed on a substrate by printing a low-reflectivity layer-forming ink by screen printing. The printing speed is preferably in the range of 50 to 300 mm / sec, more preferably in the range of 100 to 250 mm / sec. The drying temperature after printing is preferably 40 to 120°C, more preferably 60 to 120°C, and even more preferably 80 to 100°C. This improves low reflectivity. Furthermore, the viscosity of the ink during printing is preferably in the range of 700 to 12,000 cps, and more preferably in the range of 1,000 to 8,000 cps.

[0090] In the present disclosure, the film thickness of the low-reflection layer is preferably 5 μm or more, more preferably 7 μm or more, and particularly preferably 10 μm or more. When the film thickness is 5 μm or more, the transmission density is 3 or more, resulting in good light-blocking properties. The transmission density here is a value measured using an optical densitometer, and is expressed as a logarithm of the ratio of a perpendicular transmitted light beam irradiated onto the laminate to a state in which the laminate is not present. Furthermore, when the film thickness is 5 μm or more, Ra reaches the above-mentioned value, which is preferable because it further improves low reflectivity. For example, the film thickness of the low-reflection layer may be 5 μm to 500 μm, 7 μm to 100 μm, or 10 μm to 50 μm.

[0091] <Base material> In the present disclosure, the substrate used for forming the laminate is not particularly limited, and examples include various glasses such as soda glass, alkali-free glass, borosilicate glass, white plate glass, AR-coated glass, and UVIR-coated glass, inorganic material substrates such as quartz, polyester substrates such as polyethylene terephthalate, polyolefin substrates such as polyethylene, polypropylene, ethylene-vinyl acetate, and others, nylon substrates such as polyamide, acrylic substrates, polyvinyl chloride substrates, polycarbonate substrates, urethane substrates, and resin substrates such as epoxy substrates. Further, a laminate using such a substrate may also be used. A vapor-deposited substrate obtained by vapor-depositing an inorganic compound such as silica, alumina, or aluminum on the substrate can also be used, and the vapor-deposited surface may be coated with polyvinyl alcohol or the like. Further, corona treatment, frame treatment, or stretching treatment may be performed. Among these, it is preferable that the substrate is an inorganic material substrate such as glass.

Example

[0092] Hereinafter, the present disclosure will be specifically described as examples, but the present disclosure is not limited to the following examples. In the present disclosure, unless otherwise specified, "parts" represents "parts by mass" and "%" represents "% by mass".

[0093] <Dry film thickness> The dry film thickness of the low-reflection layer after drying was measured using a contact-type film thickness meter DigiMicro (manufactured by Nikon Corporation).

[0094] <OD value> The transmission density (OD value) was measured using a transmission densitometer Gretag Macbeth TD-931.

[0095] <Reflectance> Using an ultraviolet-visible spectrophotometer V-760 (manufactured by JASCO Corporation), the reflectance was measured in an integrating sphere mode with a barium sulfate white plate as a reference, and evaluated based on the average value in the wavelength range of 430 nm to 620 nm.

[0096] <Average particle diameter of colorant> The average particle size of the colorant was measured as the D50 particle size, which is the volume-integrated value measured by dynamic light scattering, using a Microtrac (manufactured by Microtrac-Bell Corporation, product name "MT3300EXII"), after diluting the pigment dispersion 100 times by weight with the measurement solvent.

[0097] <Average particle size of fine particles> The average particle size of the microparticles was measured as the D50 particle size of the volume integrated value in dynamic light scattering measurements using a Microtrac (manufactured by Microtrac-Bell Corporation, product name "MT3300EXII") in a state where the microparticles were diluted 100 times by weight with the measurement solvent.

[0098] <Hydroxyl value of binder resin> It was determined according to the method described in JIS K0070.

[0099] <Surface roughness Ra> Using a shape analysis laser microscope VK-X100 (manufactured by Keyence Corporation), an image of the low-reflection layer of the laminate was captured with an objective lens at 50x magnification, and then the arithmetic mean roughness Ra (μm) of the entire screen area was measured using the JIS B0601:2001 method.

[0100] <Example 1: Preparation of ink for forming low reflection layer> A 0.3L glass flask equipped with a stirrer and thermometer was charged with 22.4 parts of the following acrylic resin 1, 30.0 parts of isophorone (boiling point 215.2 ° C), and 16.0 parts of propylene glycol monomethyl ether acetate (boiling point 146.0 ° C). The mixture was stirred at 80 ° C for 2 hours to obtain an acrylic resin varnish with a solids content of 32.7% by mass. Next, 68.4 parts of the obtained acrylic resin varnish, 4.7 parts of the following carbon black 1, and 1.9 parts of the following dispersant were placed in a metal sealed container and dispersed using glass beads in a bead mill. 75.0 parts of the obtained carbon black dispersion were charged with 22.0 parts of the following polyester resin microparticles 1, 0.5 parts of the following defoamer, and 2.5 parts of a polyisocyanate curing agent, and the mixture was stirred with a disperser to obtain the low-reflection layer-forming ink of Example 1.

[0101] <Example 1: Preparation of laminate> Using the ink for forming a low-reflection layer obtained by the above procedure, a 5 cm x 5 cm print was produced by screen printing on a 1.1 mm thick soda glass substrate under the following screen printing conditions: After screen printing, the substrate was placed in an oven at 80°C for 1 hour to dry the ink, forming a low-reflection layer on the substrate and producing a laminate.

[0102] (Screen printing conditions) A 20 μm-thick emulsion layer made of photosensitive emulsion was formed on a polyester mesh with a mesh count of 250 mesh / inch, and the plate was made so that the bias angle was 22.5°. A urethane squeegee with a durometer A hardness of 80 was used. Screen printing was carried out at an attack angle of 75° and a squeegee speed of 100 mm / sec.

[0103] <Examples 2 to 29 and Comparative Examples 1 to 6: Preparation of ink for forming low-reflection layer> Using the raw materials and compositions shown in Tables 1 and 2, the same procedures as in Example 1 were carried out to obtain inks for forming low-reflection layers of Examples 2 to 29 and Comparative Examples 1 to 6. In the tables, values ​​without units indicate parts, and blank spaces indicate that no ingredients were blended.

[0104] <Examples 2 to 29 and Comparative Examples 1 to 6: Preparation of Laminates> Using the inks for forming low reflection layers obtained by the above procedure, laminates were produced in the same manner as in Example 1 using the inks for forming low reflection layers of Examples 2 to 29 and Comparative Examples 1 to 6.

[0105] [Table 1-1]

[0106] [Table 1-2]

[0107] [Table 2]

[0108] Acrylic resin 1: hydroxyl value 30 mg KOH / g, weight average molecular weight Mw 42000 Polyester resin 1: hydroxyl value 30 mg KOH / g, weight average molecular weight Mw 12000 Acrylic resin 2: hydroxyl value 48 mg KOH / g, weight average molecular weight Mw 43000 Vinyl chloride-vinyl acetate copolymer resin 1: hydroxyl value 30 mg KOH / g, weight average molecular weight Mw 24000 Urethane resin 1: hydroxyl value 30 mg KOH / g, weight average molecular weight Mw 80,000 Acrylic resin 3: hydroxyl value 5 mg KOH / g, weight average molecular weight Mw 40,000 Acrylic resin 4: hydroxyl value 70 mg KOH / g, weight average molecular weight Mw 48000 Carbon black 1: average particle size 150 nm, oil absorption capacity 40 cm 3 / 100g, specific surface area 15m 2 / g Carbon black 2: Average particle size 75 nm, oil absorption 78 cm 3 / 100g, specific surface area 25m 2 / g Carbon Black 3: Average particle size 220 nm, oil absorption 32 cm 3 / 100g, specific surface area 15m 2 / g Carbon Black 4: Average particle size 30 nm, oil absorption 113 cm 3 / 100g, specific surface area 76m 2 / g Carbon Black 5: Average particle size 350 nm, oil absorption 21 cm 3 / 100g, specific surface area 8m 2 / g CI Pigment Green 7: Average particle size 220nm Polyester resin microparticles 1: average particle diameter 5 μm, refractive index 1.48 Polyester resin microparticles 2: average particle diameter 1 μm, refractive index 1.48 Polyester resin microparticles 3: average particle diameter 12 μm, refractive index 1.48 Acrylic resin particles 1: average particle diameter 6 μm, refractive index 1.49 Benzoguanamine-formaldehyde condensation resin microparticles 1: average particle size 5 μm, refractive index 1.66 Polyester resin microparticles 4: average particle size 0.3 μm, refractive index 1.48 Polyester resin microparticles 5: average particle diameter 18 μm, refractive index 1.48 Spherical silica 1: average particle size 4 μm, refractive index 1.46 Isophorone: boiling point 215.2°C Cyclohexanone: boiling point 155.6℃ Propylene glycol monomethyl ether acetate: boiling point 146.0°C Toluene: boiling point 110.6℃ Dispersant: SOLSPERSE 24000 GR, manufactured by Lubrizol, 100% solids Antifoaming agent: DOWIL SH5500 Antifoam Compound, manufactured by Dow Chemical Japan, 100% solids Polyisocyanate hardener: Coronate HX, manufactured by Tosoh Corporation, NCO ratio 20.5%, solids content 100%

[0109] <Evaluation> The laminates obtained in the above Examples and Comparative Examples were evaluated as follows. The evaluation results are shown in Tables 1 and 2.

[0110] <Light blocking property> The evaluation was based on the transmittance density (OD value) measured by the above method, and the evaluation criteria were as follows: 5 (Excellent): OD value 4.5 or higher 4 (Good): OD value 3.8 or more, less than 4.5 3 (Acceptable): OD value 3.0 or more, less than 3.8 2 (Not acceptable): OD value 2.2 or more, less than 3.0 1 (poor): OD value less than 2.2 Practical ratings are 3, 4 and 5.

[0111] <Low reflectivity> The evaluation was based on the reflectance measured by the above method, and the evaluation criteria were as follows: 5 (Excellent): Less than 2.4% 4 (Good): 2.4% or more, less than 2.8% 3 (Acceptable): 2.8% or more, less than 3.2% 2 (unacceptable): 3.2% or more, less than 3.6% 1 (poor): 3.6% or more Practical ratings are 3, 4 and 5.

[0112] <Adhesion to substrate> A checkerboard peel test jig was used on the low-reflection layer to measure 1 mm 2 100 cross-cuts of this size were made. Thereafter, adhesive tape (LP24, manufactured by Nichiban Co., Ltd.) was applied to the cross-cut area and peeled off at a 90-degree angle, and the number of remaining cross-cut marks on the cured film was counted. The evaluation criteria were as follows: 5 (excellent): 96~100 pieces 4 (good): 91~95 pieces 3 (acceptable): 86~90 pieces 2 (not allowed): 81~85 pieces 1 (poor): 80 pieces or less Practical ratings are 3, 4 and 5.

[0113] <Scratch resistance> Evaluation was performed using a Gakushin-type rubbing fastness tester at 25°C and 50% humidity. A white cotton cloth was attached to the tip of a friction probe (20mm x 20mm, R45mm), and the friction probe was placed on the low-reflection layer under a load of 200gf and moved back and forth 10 times at a speed of 30 times / minute. After 10 times, the degree of rubbing off of the ink used to form the low-reflection layer was evaluated as the coloring on the white cotton cloth. The degree of coloring on the white cotton cloth was evaluated using a staining gray scale based on JIS L 0805. The evaluation criteria are as follows: 5 (Excellent): Grayscale Level 5 4 (Good): Between grayscale level 4 and 5 3 (Acceptable): Grayscale Level 4 2 (Not acceptable): Between grayscale levels 3 and 4 1 (poor): Grayscale level 3 or below Practical ratings are 3, 4 and 5.

[0114] <Moisture and heat resistance> The laminate was boiled in boiling water for 60 minutes, then removed from the hot water and allowed to stand at room temperature for 10 minutes, after which the adhesion to the substrate was evaluated by the method described above. The evaluation criteria are as follows: 5 (excellent): 96~100 pieces 4 (good): 91~95 pieces 3 (acceptable): 86~90 pieces 2 (not allowed): 81~85 pieces 1 (poor): 80 pieces or less Practical ratings are 3, 4 and 5.

[0115] Comparative Example 1, which did not contain any extender pigment and / or resin fine particles, Comparative Examples 2 and 3, in which the binder resin was not in the range of 30 to 55 mass% of the total mass of the ink solids, and Comparative Examples 4 and 5, in which a colorant with an average particle size not in the range of 50 to 250 nm was used, resulted in poor light-shielding properties, low reflectivity, substrate adhesion, scratch resistance, and moist heat resistance. In Comparative Example 6, the composition of organic solvent (A) and organic solvent (B) affected the surface roughness Ra, resulting in poor low reflectivity.

[0116] The present disclosure makes it possible to provide a low-reflectivity laminate that is excellent in light-blocking properties, low reflectivity, substrate adhesion, scratch resistance, and moist heat resistance.

[0117] The present disclosure includes the following embodiments. (Section 1) an ink for forming a low-reflection layer, the ink comprising a binder resin, a colorant, fine particles, and an organic solvent, except when the fine particles are the colorant; the content of the binder resin is more than 30% by mass and not more than 55% by mass of the total mass of the ink solids; the colorant has an average particle diameter of 50 to 250 nm; the fine particles comprise at least one selected from the group consisting of an extender pigment and a resin fine particle; the organic solvent comprises an organic solvent (A) consisting of a ketone-based organic solvent, and an organic solvent (B) consisting of at least one selected from the group consisting of a glycol ether-based organic solvent, an ester-based organic solvent, an aliphatic organic solvent, and an aromatic organic solvent; and the organic solvent (A) comprises a cyclic ketone-based organic solvent. (Section 2) Item 2. The ink for forming a low-reflection layer according to Item 1, wherein the binder resin comprises at least one selected from the group consisting of an acrylic resin, a polyester resin, and a urethane resin. (Section 3) Item 3. The ink for forming a low-reflection layer according to Item 1 or 2, wherein the colorant contains at least carbon black. (Section 4) 4. The ink for forming a low reflection layer according to any one of items 1 to 3, wherein the binder resin has a hydroxyl value of 10 to 50 mgKOH / g. (Section 5) The total mass of the colorant and the fine particles is 40 to 55 mass % of the total mass of the ink solids. 4 10. The ink for forming a low reflection layer according to claim 9. (Section 6) Item 6. The ink for forming a low reflection layer according to any one of items 1 to 5, wherein the fine particles have an average particle size of 0.5 to 15 μm. (Section 7) Item 7. The ink for forming a low-reflection layer according to any one of items 1 to 6, wherein the fine particles are resin fine particles, and the resin fine particles include at least one selected from the group consisting of polyester resin fine particles and acrylic resin fine particles. (Section 8) Item 8. The ink for forming a low reflection layer according to any one of items 1 to 7, wherein a mass ratio of the colorant to the fine particles (fine particles / colorant) is in the range of 3 to 5. (Section 9) Item 3. The ink for forming a low-reflection layer according to Item 1 or 2, wherein the boiling point of the organic solvent (A) is higher than the boiling point of the organic solvent (B). (Section 10) Item 10. The ink for forming a low reflection layer according to any one of items 1 to 9, wherein the difference in boiling point between the organic solvent (A) and the organic solvent (B) is 35 to 80°C. (Section 11) Item 11. A low-reflection laminate comprising a substrate and a low-reflection layer provided on the substrate and made of the ink for forming a low-reflection layer according to any one of items 1 to 10. (Section 12) A method for forming a low-reflection layer, which includes printing a low-reflection layer-forming ink on a substrate to form a low-reflection layer, wherein the ink for forming a low-reflection layer is the ink for forming a low-reflection layer according to any one of items 1 to 10, and the method for forming a low-reflection layer includes a drying step of volatilizing the organic solvent.

[0118] The disclosure of this application is related to the subject matter described in Japanese Patent Application No. 2022-202075 filed on December 19, 2022 and Japanese Patent Application No. 2023-082715 filed on May 19, 2023, the entire disclosures of which are incorporated herein by reference.

Claims

1. An ink for forming a low-reflection layer, comprising a binder resin, a colorant, fine particles, and an organic solvent, excluding the case where the fine particles are the colorant, wherein the content of the binder resin is more than 30% by mass and not more than 55% by mass of the total mass of the ink solids, the average particle diameter of the colorant is 50 to 250 nm, the fine particles comprise at least one selected from the group consisting of extender pigments and resin fine particles, the organic solvent comprises an organic solvent (A) consisting of a ketone-based organic solvent, and an organic solvent (B) consisting of at least one selected from the group consisting of glycol ether-based organic solvents, ester-based organic solvents, aliphatic organic solvents, and aromatic organic solvents, and the organic solvent (A) comprises a cyclic ketone-based organic solvent.

2. The ink for forming a low reflection layer according to claim 1, wherein the binder resin comprises at least one resin selected from the group consisting of acrylic resin, polyester resin, and urethane resin.

3. The ink for forming a low reflection layer according to claim 1 or 2, wherein the colorant contains at least carbon black.

4. The ink for forming a low reflection layer according to claim 1 or 2, wherein the hydroxyl value of the binder resin is 10 to 50 mgKOH / g.

5. The ink for forming a low-reflection layer according to claim 1 or 2, wherein the total mass of the colorant and the fine particles is 40 to 55 mass % of the total mass of the ink solids.

6. The ink for forming a low reflection layer according to claim 1 or 2, wherein the average particle diameter of the fine particles is 0.5 to 15 μm.

7. The ink for forming a low reflection layer according to claim 1 or 2, wherein the fine particles are resin fine particles, and the resin fine particles include at least one kind selected from the group consisting of polyester resin fine particles and acrylic resin fine particles.

8. The ink for forming a low reflection layer according to claim 1 or 2, wherein the mass ratio of the colorant to the fine particles (fine particles / colorant) is in the range of 3 to 5.

9. The ink for forming a low reflection layer according to claim 1 or 2, wherein the boiling point of the organic solvent (A) is higher than the boiling point of the organic solvent (B).

10. The ink for forming a low reflection layer according to claim 1 or 2, wherein the difference in boiling point between the organic solvent (A) and the organic solvent (B) is 35 to 80°C.

11. A low-reflection laminate comprising a substrate and a low-reflection layer provided on the substrate and made of the ink for forming a low-reflection layer according to claim 1 or 2.

12. A method for forming a low-reflection layer, which comprises printing an ink for forming a low-reflection layer on a substrate to form a low-reflection layer, wherein the ink for forming a low-reflection layer is the ink for forming a low-reflection layer according to claim 1 or 2, and the method for forming a low-reflection layer comprises a drying step of volatilizing the organic solvent.

Images