Classifications

• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
  • C09D11/00—Inks
  • C09D11/02—Printing inks
  • C09D11/03—Printing inks characterised by features other than the chemical nature of the binder
  • C09D11/037—Printing inks characterised by features other than the chemical nature of the binder characterised by the pigment
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
  • C09D11/00—Inks
  • C09D11/02—Printing inks
  • C09D11/10—Printing inks based on artificial resins
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
  • C09D11/00—Inks
  • C09D11/02—Printing inks
  • C09D11/10—Printing inks based on artificial resins
  • C09D11/102—Printing inks based on artificial resins containing macromolecular compounds obtained by reactions other than those only involving unsaturated carbon-to-carbon bonds
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
  • C09D11/00—Inks
  • C09D11/02—Printing inks
  • C09D11/10—Printing inks based on artificial resins
  • C09D11/102—Printing inks based on artificial resins containing macromolecular compounds obtained by reactions other than those only involving unsaturated carbon-to-carbon bonds
  • C09D11/104—Polyesters
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B5/00—Optical elements other than lenses

Definitions

• This disclosure relates to an ink for forming a low-reflection layer, a low-reflection laminate, and a method for forming a low-reflection layer.
• 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 excellent low reflectivity and light-shielding properties on the surface of the low-reflection layer, and a method for forming a low-reflection layer.
• low-reflective black ink is applied to the sides and edges of lenses to remove unnecessary incident and reflected light and suppress the occurrence of flare and ghosting, which are factors that reduce image quality.
• ToF Time of Flight
• low-reflective paint is applied around the light source to suppress internal reflections of the light source laser.
• low-reflectivity colored inks are expected to add design appeal in the field of packaging for consumer goods.
• low reflectivity is also required for green screens used as backgrounds for subjects to improve image quality.
• Patent Document 1 a surface anti-reflective coating film that uses a surface anti-reflective paint for mist application that contains a binder resin, carbon black, hydrophobically treated dry silica, roughening particles, dyes, and solvents.
• this method imparts black color by using carbon black in combination with a dye, but since the dye has low light resistance, there is a concern that the low reflectivity will deteriorate over time.
• this composition is for mist 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 and low reflectivity is difficult to obtain.
• the amount of silica as a matting agent is excessive, and there is a possibility that scratch resistance and reverse gloss will be inferior.
• Patent Documents 2 and 3 describe a low-reflection film using carbon black, and an optical sensing kit and low-reflection molded body using the same.
• the average particle size (D50) of the colorant carbon black is small at 25 nm, and it has high transparency in the visible light region, so there is concern that the light blocking properties may be insufficient.
• the content of the acrylic resin, which is the binder resin is low, so there are problems with adhesion to the substrate, etc. Therefore, a technology that satisfies the characteristics of a low-reflection laminate has not yet been obtained.
• JP 2020-97730 A WO2020/195693 JP 2021-140072 A
• the present disclosure aims to provide an ink for forming a low-reflective layer that has excellent light-blocking properties and low reflectivity, as well as excellent adhesion to a substrate, scratch resistance, and moist heat resistance, a low-reflective laminate, and a method for forming a low-reflective layer.
• the present disclosure relates to an ink for forming a low-reflection layer, which contains a binder resin, a colorant, fine particles (except when the fine particles are the colorant) and an organic solvent, in which 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.
• the present disclosure also relates to the ink for forming a low-reflection layer, in which the binder resin contains at least one resin selected from the group consisting of acrylic resin, polyester resin, and urethane resin.
• the present disclosure also relates to the ink for forming the low-reflection layer, in which the colorant contains at least carbon black.
• the present disclosure also relates to the ink for forming a low-reflective layer, in which the binder resin has a hydroxyl value of 10 to 50 mgKOH/g.
• the present disclosure also relates to the ink for forming a low-reflection layer, in which the total mass of the colorant and the fine particles is 40 to 55 mass% of the total mass of the ink solids.
• the present disclosure also relates to the ink for forming a low-reflective layer, in which the average particle size of the microparticles is 0.5 to 15 ⁇ m.
• the present disclosure also relates to the ink for forming a low-reflection layer, in which the fine particles are resin fine particles, and the resin fine particles include at least one type selected from the group consisting of polyester resin fine particles and acrylic resin fine particles.
• the present disclosure also relates to the ink for forming the low-reflective layer, in which the mass ratio of colorant to microparticles (microparticles/colorant) is in the range of 3 to 5.
• the present disclosure also relates to the ink for forming a low-reflective layer, in which the organic solvent contains 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.
• organic solvent A
• B organic solvent
• the present disclosure also relates to the ink for forming a low-reflective layer, in which the difference in boiling point between organic solvent (A) and organic solvent (B) is 35 to 80°C.
• the present disclosure also relates to a low-reflection laminate having a low-reflection layer made of the ink for forming a low-reflection layer on a substrate.
• 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, the ink being the low-reflection layer-forming ink described above, and which includes a drying step for volatilizing the organic solvent.
• This disclosure makes it possible to provide an ink for forming a low-reflective layer that has excellent light-blocking properties and low reflectivity, as well as excellent adhesion to a substrate, scratch resistance, and moist heat resistance, a low-reflective laminate, and a method for forming a low-reflective layer.
• low reflection is synonymous with “anti-reflection” as described in the prior art, and refers to a lower reflectance than the layer before improvement.
• the "low reflection laminate” may be simply referred to as the “laminate”
• the "ink for forming a low reflection layer” may be simply referred to as the “printing ink” or “ink,” but they are synonymous.
• 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 based on 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.
• the binder resin content in the ink within the above range, the ink layer formed after drying has good adhesion to the substrate, scratch resistance, and moist heat resistance.
• the ink fluidity is maintained good while the light shielding property and low reflectivity are improved, so that the ink layer formed has low reflection and can satisfy light shielding property, substrate adhesion property, scratch resistance, and moist heat resistance.
• a low-reflection laminate including a low-reflection layer made of the ink for forming a low-reflection layer of the present disclosure inside the lens barrel of a camera module for a smartphone or an in-vehicle sensor or around an image sensor, it can contribute to suppressing phenomena such as ghosts and flares.
• this function is based on consideration and does not particularly limit the present disclosure.
• 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 obtained print becomes a low reflection laminate.
• the binder resin refers to a resin that can function as a binding agent in the ink, and is preferably a thermoplastic resin.
• the thermoplastic resin include acrylic resin, polyester resin, urethane resin, vinyl chloride-vinyl acetate copolymer resin, epoxy resin, styrene-based resin, rosin-based resin, styrene-maleic acid resin, dammar resin, polycarbonate resin, rosin-modified maleic acid resin, rosin ester resin, and terpene resin. These resins may be used in combination as long as the effects of the present disclosure are not impaired. 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.
• 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.
• the content of the binder resin in the ink is excessive, the uneven shape of the low reflection layer surface is likely to be flattened, which may cause a decrease in low reflectivity.
• 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.
• Acrylic resin is a binder resin that has excellent environmental resistance and scratch resistance, but it has slightly poor adhesion to the substrate and tends to be difficult to form uneven surfaces.
• 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 the uneven surface shape and obtain good low reflectivity while obtaining sufficient adhesion to the substrate.
• the uneven surface shape of the low reflection layer can be more appropriately formed during the ink layer formation process, making it possible to further improve low reflectivity.
• the amount of hydroxyl groups in the binder resin in order to provide adhesion of the ink layer to the substrate. Since the average particle size of the colorant and the amount of binder resin contained in the ink are appropriately controlled, it is possible to suppress a decrease in low reflectivity even when the amount of hydroxyl groups in the binder resin is within a range suitable for substrate adhesion.
• the binder resin content is in the range of more than 30% by mass and not more than 55% by mass, preferably in the range of 32-55% by mass, and even more preferably in the range of 35-50% by mass, of the total mass of the ink solids.
• 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 value of 10 mgKOH/g or more provides good adhesion to the substrate, and a value of 50 mgKOH/g or less provides good resistance to moist heat.
• the hydroxyl value of the binder resin is the amount of hydroxyl groups in 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 is a value measured in accordance with JIS K0070.
• 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.
• a weight average molecular weight of 5,000 or more improves printability, and a weight average molecular weight of 120,000 or less improves scratch resistance.
• the weight average molecular weight is a polystyrene-equivalent value measured by GPC (gel permeation chromatography).
• 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.
• colorants used in the present disclosure include various organic pigments, inorganic pigments, dyes, etc., and these can be used in combination within a range that does not impair the effects of the present disclosure. However, it is preferable to use carbon black from the viewpoints of light blocking properties and low reflectivity.
• 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. By making it 50 nm or more, the fluidity of the ink is improved, and by making it 250 nm or less, the light blocking property and low reflectance are improved.
• the average particle size refers to the D50 particle size of the volume integrated value measured by dynamic light scattering, and can be measured, for example, by a Microtrack (manufactured by Microtrack Bell, product name "MT3300EXII"). Measurement samples can be prepared appropriately depending on the measurement device, but for example, a particle dispersion is prepared by diluting it 100 times by weight with a measurement solvent.
• Carbon black used in the present disclosure may be any known one, and examples of such carbon black include C.I. Pigment Black 7, as indicated by the C.I. number of the Color Index International (abbreviated as C.I.).
• the oil absorption of the carbon black is preferably in the range of 10 to 150 cm3 /100g, and more preferably in the range of 20 to 100 cm3 /100g. By setting the oil absorption in this range, sufficient density of the printed matter can be obtained and the light blocking properties are good.
• the oil absorption is measured according to JIS K6221, and is the amount of DBP (dibutyl phthalate) absorbed by 100 g of carbon black.
• the specific surface area of the carbon black (as measured by nitrogen adsorption) is preferably in the range of 5 to 200 m 2 /g, and more preferably in the range of 10 to 150 m 2 /g. By setting the specific surface area within this range, the printability is improved.
• carbon black examples 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.), SUNBLACK 235, Asahi #8, and Asahi #15 (manufactured by Asahi Carbon Co., Ltd.).
• organic pigments other than the above carbon black that can be preferably used as colorants, listed by color index number.
• Yellow pigments include C.I. 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, 1 25, 126, 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,
• Red pigments include C.I. 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 preferably used.
• C.I. 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.
• C.I. Pigment Orange 36, 38, 43, 51, 55, 59, 61, 71, 73, etc. can be suitably used.
• C.I. Pigment Green 7, 10, 36, 37, 58, 62, 63, etc. can be suitably used as green pigments.
• C.I. Pigment Violet 1 19, 27, 29, 30, 32, 37, 40, 42, 50, etc. can be suitably used.
• 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, and iron black. Inorganic pigments are preferably used in combination with organic pigments to ensure good coatability, sensitivity, developability, and other properties while maintaining a balance between saturation and brightness.
• the colorant content is preferably in the range of 5 to 15% by mass, and more preferably in the range of 7 to 12% by mass, based on the total mass of the ink solids.
• a content of 5% by mass or more improves the light blocking properties, while a content of 15% by mass or less improves adhesion to the substrate and scratch resistance.
• 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 the case where the extender pigment and/or resin fine particles are slightly colored.
• the average particle size of the microparticles is preferably in the range of 0.5 to 15 ⁇ m, and more preferably in the range of 2 to 10 ⁇ m.
• the average particle size 0.5 ⁇ m 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 ⁇ m or less, the scratch resistance of the low-reflection layer surface is good.
• the refractive index of the fine particles used in this 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, low reflectivity is further improved.
• the content of the fine particles is preferably in the range of 25 to 50% by mass of the total mass of the ink solids, and more preferably in the range of 35 to 45% by mass.
• a content ratio of 25% by mass or more improves low reflectivity, and a content ratio of 50% by mass or less improves scratch resistance.
• the extender pigment for example, one or more of the following may be used, but is not limited to: silica fine particles, alumina fine particles, talc fine particles, calcium carbonate fine particles, kaolin fine particles, precipitated barium sulfate fine particles, etc.
• resin microparticles examples include polyester resin microparticles, acrylic resin microparticles, melamine resin microparticles, melamine-benzoguanamine resin microparticles, benzoguanamine-formaldehyde condensed resin microparticles, fluororesin microparticles, urethane resin microparticles, and cellulose resin microparticles.
• polyester resin microparticles and/or acrylic microparticles are preferred, and polyester resin microparticles are even more preferred.
• one or more types may be used, and the resin microparticles applicable to the present disclosure are not limited to these.
• polyester resin microparticles examples include polyester resin microparticles made of polyhydroxyalkanoic acid, polyester resin microparticles made of a condensate of dibasic acid and diol, and polylactic acid resin microparticles. Of these, polyester resin microparticles made of polyhydroxyalkanoic acid and polyester resin microparticles made of a condensate of dibasic acid and diol are preferred, and polyester resin microparticles made of polyhydroxyalkanoic acid are more preferred. In addition, it is also preferred to use polyester resin microparticles made of biodegradable resin as the polyester resin microparticles.
• polyester resin microparticles include the Techpolymer TP-MG series (manufactured by Sekisui Chemical Co., Ltd.). Methods for producing polyester microparticles include the methods described in JP-A-2007-191617 and JP-A-5-194141.
• 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.), etc.
• 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 the melamine-benzoguanamine resin fine particles is Eposter M30 (manufactured by Nippon Shokubai Co., Ltd.).
• benzoguanamine-formaldehyde condensation resin microparticles include Eposter MS and Eposter L15 (manufactured by Nippon Shokubai Co., Ltd.).
• 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 the melamine-benzoguanamine resin fine particles is Eposter M30 (manufactured by Nippon Shokubai Co., Ltd.).
• benzoguanamine-formaldehyde condensation resin microparticles include Eposter MS and Eposter L15 (manufactured by Nippon Shokubai Co., Ltd.).
• fluororesin microparticles include KTL-1N, KTL-2N, KTL-8N (manufactured by Kitamura Co., Ltd.), Shamrock SST-3D, Shamrock SST-4MG (manufactured by Shamrock Technologies), etc.
• urethane microparticles include cross-linked 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 Industries Co., Ltd.).
• the total amount of colorant and fine particles is preferably in the range of 40 to 55% by mass of the total mass of the ink solids, and more preferably in the range of 45 to 50% by mass.
• a content of 40% by mass or more provides good light blocking properties and low reflectivity, while a content of 55% by mass or less provides good adhesion to the substrate, scratch resistance, and moist heat resistance.
• 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.
• the ratio 3 or more good low reflectivity is achieved, and by making it 5 or less, good light blocking properties are achieved.
• the printing ink preferably contains an organic solvent.
• the organic solvent include glycol ether-based organic solvents, ester-based organic solvents, aliphatic organic solvents, aromatic organic solvents, alcohol-based organic solvents, and ketone-based organic solvents.
• the two or more organic solvents have different boiling points.
• the low boiling point solvent volatilizes on the substrate surface, followed by the high boiling point solvent, resulting in a difference in drying speed.
• This difference in drying speed makes it possible to obtain a more appropriate low reflectivity in the obtained low reflection layer.
• one index of low reflectivity is the surface roughness Ra.
• the uneven shape of the surface of the low-reflection layer can be suitable for low reflectivity, as described above.
• the low-reflection layer obtained using the ink for forming a low-reflection layer preferably has a surface roughness Ra of 3 to 5 ⁇ m.
• organic solvent (A) and organic solvent (B) are used, it is preferable that the boiling point of organic solvent (A) is higher than that of organic solvent (B).
• organic solvent (B) with a low boiling point volatilizes first, and then organic solvent (A) tends to volatilize.
• the binder resin dissolved in organic solvent (A) encapsulates the colorant and fine particles, and the colorant and fine particles can be more uniformly fixed to the substrate on the surface of the substrate.
• the surface roughness Ra of the obtained low reflection layer can be set to a more appropriate range, for example, 3 to 5 ⁇ m.
• 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.
• cyclic ketone-based organic solvents are preferable because they have a higher boiling point than other ketone-based solvents and are excellent in printability.
• cyclic ketone-based organic solvents are preferable because they can increase the boiling point difference with respect to the organic solvent (B), and the effect of forming the unevenness of the low reflection layer due to the boiling point difference is high.
• 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.
• 6-membered cyclic ketone organic solvent examples 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.
• Examples of the ketone solvent not having a cyclic skeleton include acetone, methyl ethyl ketone, methyl isobutyl ketone, and diisobutyl ketone.
• the organic solvent (A) may be one type, or two or more types may be combined. In the case of a combination of two or more types, the organic solvent (A) is preferably a single type of cyclic ketone organic solvent, or may be a combination of a cyclic ketone organic solvent and another organic solvent (A).
• 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. Being in this range improves printability and low reflectivity.
• 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.
• the organic solvent (B) includes at least one selected from glycol ether-based organic solvents, ester-based organic solvents, aliphatic organic solvents, and aromatic organic solvents. Among them, from the viewpoint of printability, it is preferable to include a glycol ether-based organic solvent or an ester-based organic solvent. However, the organic solvent (B) does not include the organic solvent (A).
• 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.
• 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.
• Aliphatic organic solvents include normal paraffin solvents, isoparaffin solvents, cycloparaffin solvents, etc.
• aromatic organic solvents examples include toluene, xylene, ethylbenzene, naphthalene, tetralin, and solvent naphtha, as well as aromatic-rich solvents such as 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 Corporation).
• the organic solvent (B) may be one type, or a combination of two or more types.
• the organic solvent (B) is preferably one of a glycol ether-based organic solvent and an ester-based organic solvent used alone, or may be a combination of one of a glycol ether-based organic solvent and an ester-based organic solvent with another organic solvent (B).
• 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.
• 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 applied to the substrate surface, and then organic solvent (B) is volatilized and removed, allowing the binder resin, colorant, and fine particles to be encapsulated in organic solvent (A) and fixed to the substrate surface in a uniform state.
• the boiling point of the organic solvent (B) is preferably 100 to 270°C, more preferably 120 to 250°C, and even more preferably 140 to 230°C. Being in this range improves printability and low reflectivity.
• the organic solvent (B) contains at least one of a glycol ether-based organic solvent and an ester-based organic solvent
• the boiling points of the glycol ether-based organic solvent and the ester-based organic solvent are preferably 100 to 200°C, 100 to 180°C, 100 to 160°C, or 100 to 150°C, respectively, from the viewpoint of ensuring the uneven shape of the low-reflection layer depending on the drying speed, and more preferably 110 to 160°C, or 110 to 150°C.
• organic solvent (B) has a low boiling point, and it is preferable that the boiling point difference between organic solvent (A) and organic solvent (B) satisfies the following range.
• 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.
• 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, based on the total mass of the ink for forming a low reflection layer, in order to improve the solubility of the resin.
• the organic solvent (A) and the organic solvent (B) can be mixed 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.
• a polyisocyanate-type curing agent can be appropriately blended in the ink for forming the low reflection layer as long as the object of the present disclosure is not impaired.
• the content of the hardener is preferably such that the ratio NCO/OH of the amount of effective isocyanate in the hardener to the amount of hydroxyl groups in the binder resin in the ink solids is in the range of 0.5 to 1.5, and more preferably in the range of 0.75 to 1.25.
• the ink for forming the low reflection layer may contain additives such as dispersants, defoamers, leveling agents, wetting and penetrating agents, antiskinning agents, UV absorbers, antioxidants, crosslinking agents, preservatives, antifungal agents, viscosity adjusters, and pH adjusters, as necessary, within a range that does not impair the object of the present disclosure.
• additives such as dispersants, defoamers, leveling agents, wetting and penetrating agents, antiskinning agents, UV absorbers, antioxidants, crosslinking agents, preservatives, antifungal agents, viscosity adjusters, and pH adjusters, as necessary, within a range that does not impair the object of the present disclosure.
• the ink for forming a low-reflection layer used in the present disclosure can be produced by mixing the required amounts of a binder resin, a colorant, fine particles, an organic solvent, and, if necessary, a curing agent and/or additives, and thoroughly stirring the mixture with a stirrer or the like, or by first preparing a dispersion containing a colorant, a dispersant, and an organic solvent, and then mixing the required amounts of a binder resin, an organic solvent, a curing agent, and/or additives, and thoroughly stirring the mixture with a stirrer or the like.
• printing methods for forming a low reflection layer on a substrate include screen printing, roll coater, dispenser coating, dip coating, brush coating, etc., among which screen printing is preferred.
• a cylinder press printing machine or a semi-automatic printing machine is preferably used, and as the printing plate, a resin material such as nylon or polyester, or a resin material such as stainless steel is preferably used.
• Screen printing is a technique that uses a screen made of chemical fibers such as polyester or nylon or stainless steel as a plate, patterns the areas where the ink passes through and the areas where it does not pass through using a photosensitive emulsion on the plate, and then transfers the ink to the substrate by pressing and moving the ink on the inner surface of the screen with a spatula-shaped rubber plate called a squeegee.
• the angle of the weave direction of the mesh with respect to the screen frame is called the bias angle.
• the thickness of the printed ink can be adjusted by the 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.
• the ink can be fixed to the substrate by evaporating the solvent in the ink using a hot air oven.
• the present disclosure relates to 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, the ink comprising a binder resin, a colorant, fine particles, and an organic solvent.
• the content of the binder resin is 30 to 55% by mass based on the total mass of the ink solids
• the average particle size of the colorant is 50 to 250 nm
• the method includes a drying step of volatilizing the organic solvent.
• the segregated fine particles form an uneven shape on the surface of the low reflection layer, and the low reflection layer can be formed. Furthermore, due to the above-mentioned drying mechanism of the organic solvent, This makes it possible to effectively segregate the fine particles.
• the surface roughness Ra of the low-reflection layer is preferably 3 to 5 ⁇ m, and more preferably 3.5 to 5 ⁇ m. If the surface roughness Ra is in the above range, there is an advantage that the low reflectivity is improved.
• Surface roughness Ra is the arithmetic average roughness, and refers to the measured value according to the JIS B0601:2001 method using a shape analysis laser microscope.
• the low-reflectivity layer is preferably formed by printing the low-reflectivity layer-forming ink on the substrate 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.
• 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.
• the film thickness of the low-reflection layer is preferably 5 ⁇ m or more, more preferably 7 ⁇ m or more, and particularly preferably 10 ⁇ m or more.
• the transmission density is 3 or more, and the light blocking properties are good.
• the transmission density is a value measured using an optical densitometer, and is expressed as a logarithm of the ratio when a vertical transmitted light beam is irradiated onto the laminate and when there is no laminate.
• Ra becomes the above value, and low reflectivity is further improved, which is preferable.
• the film thickness of the low-reflection layer may be 5 ⁇ m to 500 ⁇ m, 7 ⁇ m to 100 ⁇ m, or 10 ⁇ m to 50 ⁇ m.
• the substrate used to form the laminate is not particularly limited, and examples thereof include various types of glass 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, polyethylene, polypropylene, ethylene-vinyl acetate, and other polyolefin substrates, nylon substrates such as polyamide, acrylic substrates, polyvinyl chloride substrates, polycarbonate substrates, urethane substrates, and resin substrates such as epoxy substrates. A laminate using such substrates may also be used.
• glass 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, polyethylene, polypropylene, ethylene-vinyl acetate, and other polyolefin substrate
• a deposition substrate in which an inorganic compound such as silica, alumina, or aluminum is deposited on the substrate may also be used, and the deposition-treated surface may be further subjected to a coating treatment with polyvinyl alcohol or the like. Corona treatment, frame treatment, and stretching treatment may also be performed. Of the above, an inorganic material substrate such as glass is preferable.
• ⁇ Dry film thickness> The dry film thickness of the low reflective layer after drying was measured using a contact film thickness meter DigiMicro (manufactured by Nikon Corporation).
• ⁇ OD value> The transmission density (OD value) was measured using a transmission densitometer Gretag Macbeth TD-931.
• the reflectance was measured in an integrating sphere mode using a UV-visible spectrophotometer V-760 (manufactured by JASCO Corporation) with a barium sulfate white plate as a reference, and evaluated as an average value in the wavelength range of 430 nm to 620 nm.
• the average particle size of the colorant was determined as the D50 particle size, which is a volume-integrated value in the measurement by dynamic light scattering, by measuring the pigment dispersion diluted 100 times by weight with a measurement solvent using a Microtrack (manufactured by Microtrack-Bell Corporation, product name "MT3300EXII").
• the average particle diameter of the microparticles was determined as the D50 particle diameter of the volume integrated value in the dynamic light scattering measurement, and was measured using a Microtrac (manufactured by Microtrac Bell, product name "MT3300EXII") in a state where the microparticles were diluted 100 times by weight using a measurement solvent.
• Example 1 Preparation of ink for forming low reflection layer
• 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.) were charged, and stirred at 80 ° C. for 2 hours to obtain an acrylic resin varnish with a solid content of 32.7% by mass.
• 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 beads mill dispersion was performed using glass beads.
• 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 printed portion was produced by screen printing on a soda glass substrate having a thickness of 1.1 mm 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, thereby forming a low-reflection layer on the substrate and producing a laminate.
• 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 procedure as in Example 1 was carried out to obtain inks for forming low reflective layers of Examples 2 to 29 and Comparative Examples 1 to 6. In the tables, values without unit notation represent parts, and blanks represent no blend.
• 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.
• Acrylic resin 1 hydroxyl value 30 mg KOH/g, weight average molecular weight Mw 42,000 Polyester resin 1: hydroxyl value 30 mgKOH/g, weight average molecular weight Mw 12000 Acrylic resin 2: hydroxyl value 48 mg KOH/g, weight average molecular weight Mw 43,000 Vinyl chloride-vinyl acetate copolymer resin 1: hydroxyl value 30 mg KOH/g, weight average molecular weight Mw 24,000 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 48,000 ⁇ Carbon black 1: average particle diameter 150 nm, oil absorption 40 cm 3 /100 g, specific surface area 15 m 2 /g ⁇ Carbon black 2: average particle diameter 75 nm, oil absorption 78 cm 3 /100g,
• Polyester resin particles 1 average particle diameter 5 ⁇ m, refractive index 1.48
• Polyester resin particles 2 average particle diameter 1 ⁇ m, refractive index 1.48
• Polyester resin particles 3 average particle diameter 12 ⁇ m, refractive index 1.48
• Acrylic resin particles 1 average particle diameter 6 ⁇ m, refractive index 1.49
• Benzoguanamine-formaldehyde condensation resin microparticles 1 average particle size 5 ⁇ m, refractive index 1.66
• Polyester resin particles 4 average particle size 0.3 ⁇ m, refractive index 1.48
• Polyester resin particles 5 average particle size 18 ⁇ m, refractive index 1.48
• Spherical silica 1 average particle size 4 ⁇ m, refractive index 1.46
• Isophorone boiling point 215.2°C
• Cyclohexanone boiling point 155.6°C
• Propylene glycol monomethyl ether acetate boiling point 146.0°C
• Toluene boiling point 110.6°C
• Dispersant SOLSPERSE 24000 GR, manufactured by
• a checkerboard peel test tool was used to make 100 cross-cuts of 1 mm2 on the low reflection layer. Thereafter, adhesive tape (LP24, manufactured by Nichiban Co., Ltd.) was applied onto the cross-cut area and peeled off at an angle of 90 degrees, and the number of remaining cross-cut marks in the cured film was counted. 5 (Excellent): 96-100 pieces 4 (Good): 91-95 pieces 3 (Fair): 86-90 pieces 2 (Unacceptable): 81-85 pieces 1 (Poor): 80 pieces or less Practical usable ratings are 3, 4 and 5.
• Grayscale grade 5 (Excellent): Grayscale grade 5 4 (Good): Between grayscale grades 4 and 5 3 (Fair): Grayscale grade 4 2 (Unacceptable): Between grayscale grades 3 and 4 1 (Poor): Grayscale grade 3 or below Practical usable ratings are 3, 4 and 5.
• Comparative Example 1 which does not contain extender pigments and/or resin particles
• Comparative Examples 2 and 3 which do not contain binder resins in the range of 30-55% by mass of the total ink solids
• Comparative Examples 4 and 5 which use colorants with average particle sizes not in the range of 50-250 nm, all showed poor light blocking, low reflectivity, substrate adhesion, scratch resistance, and moist heat resistance.
• Comparative Example 6 showed poor low reflectivity due to the composition of organic solvent (A) and organic solvent (B).
• This disclosure makes it possible to provide a low-reflectivity laminate that has excellent light-blocking properties, low reflectivity, adhesion to substrates, scratch resistance, and moist heat resistance.
• An ink for forming a low reflection layer comprising a binder resin, a colorant, fine particles, and an organic solvent, except when 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 based on the total mass of the ink solids, the colorant has an average particle size of 50 to 250 nm, the fine particles include at least one selected from the group consisting of an extender pigment and a resin fine particle, the organic solvent includes 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) includes a cyclic ketone-based organic solvent.
• (Item 2) 2. The ink for forming a low reflection layer according to item 1, 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. (Item 3) 3. The ink for forming a low reflection layer according to item 1 or 2, wherein the colorant contains at least carbon black. (Item 4) Item 4. The ink for forming a low reflective layer according to any one of Items 1 to 3, wherein the binder resin has a hydroxyl value of 10 to 50 mgKOH/g. (Item 5) Item 6.
• Item 6 Item 6.
• Item 7 Item 7.
• Item 8 Item 8.
• (Item 9) 3.
• (Item 10) Item 10.
• Item 11 Item 11.
• a low-reflection laminate comprising a substrate and a low-reflection layer formed on the substrate and made of the ink for forming a low-reflection layer according to any one of Items 1 to 10.
• (Item 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, the ink being the low-reflection layer-forming ink according to any one of items 1 to 10, and comprising a drying step of volatilizing the organic solvent.

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