Infrared-cutting hard coat resin composition, and hard coat film using the same

Abstract

The present invention provides an infrared-cutting hard coat resin composition that has equivalent appearance and optical properties even without containing PFAS, and exhibits good adhesion to a polycarbonate substrate, as well as a hard coat film using the same. [Solution] An infrared-cutting hard coat resin composition comprising a polyfunctional (meth)acrylate monomer, an infrared-absorbing component, a silicone-based leveling agent, and a photopolymerization initiator, wherein the silicone-based leveling agent comprises a hydroxyl group-containing silicone-modified acrylic, and the photopolymerization initiator comprises an oxime ester type.

Description

Technical Field

[0001] The present invention relates to a hard coat resin composition having an infrared cut function and a hard coat film using the same.

Background Art

[0002] In recent years, there has been an increasing interest in head-up displays (hereinafter referred to as HUDs) that display driving support information for drivers as images on the front glass of automobiles, and some vehicle models have been equipped with them. The most common method of realizing a HUD is a form in which an image is reflected and projected from a display unit onto the front glass. However, in this method, since sunlight from the front glass is condensed on the display unit, there is a problem that an image display device such as an LCD element constituting the display unit tends to become high in temperature and is liable to thermally deteriorate. Therefore, heat insulation for the display unit is required.

[0003] Here, the image data projected from the image display device is reflected and enlarged by a magnifying lens through a diffusion plate and displayed on the front glass through a cover film. Therefore, it is useful as a heat insulation measure to use an infrared cut film in which a composition that absorbs infrared rays as a material having heat ray shielding is applied to such a cover film.

[0004] As such a heat insulation film, for example, a heat insulation film provided with an infrared absorption layer containing an oxide having infrared absorption ability, an acrylic compound not containing fluorine, and an acrylic compound containing fluorine on a transparent substrate having a retardation value of 100 nm or less has been proposed (Patent Document 1). However, the resin composition used for this film does not have sufficient heat-resistant adhesion when the substrate is polycarbonate. For example, when left in an environment of 85°C for 24 hours, the adhesion may not be sufficient.

[0005] Furthermore, in recent years, the perfluorinated compounds (hereinafter referred to as PFAS) used here have become a concern due to their poor biodegradability and bioaccumulation potential, and there are movements, mainly in Europe, to restrict their use. Therefore, there has been a need for an infrared-cutting hard coat resin composition that can obtain equivalent levels of appearance and optical properties without using PFAS, and that has good adhesion to polycarbonate substrates. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Patent No. 7241324 [Overview of the Initiative] [Problems that the invention aims to solve]

[0007] The present invention aims to provide an infrared-cutting hard coat resin composition that does not contain PFAS and has good adhesion to a polycarbonate substrate, and a hard coat film using the same. [Means for solving the problem]

[0008] To solve the above problems, the invention described in claim 1 provides an infrared-cutting hard coat resin composition comprising a polyfunctional (meth)acrylate monomer (A), an infrared-absorbing component (B), a silicone-based leveling agent (C), and a photopolymerization initiator (D), wherein (C) comprises a hydroxyl group-containing silicone-modified acrylic, and (D) comprises an oxime ester type.

[0009] Furthermore, the invention described in claim 2 provides the infrared-cutting hard coat resin composition according to claim 1, characterized in that it further comprises a stabilizer (E).

[0010] Furthermore, the invention described in claim 3 provides a hard coat film having a cured layer of the infrared-cutting hard coat resin composition described in either claim 1 or 2.

[0011] Furthermore, the invention described in claim 4 provides a head-up display device using the hard coat film described in claim 3. [Effects of the Invention]

[0012] The infrared-cutting hard coat resin composition of the present invention has an equivalent level of appearance and optical properties even without containing PFAS, and also has good adhesion to polycarbonate (hereinafter referred to as PC) substrates, making it useful as a hard coat (hereinafter referred to as HC) resin for environmentally friendly infrared-cutting hard coat films. [Modes for carrying out the invention]

[0013] The present invention will be described in detail below.

[0014] The infrared-cutting HC resin composition of the present invention (hereinafter referred to as "this composition") comprises a polyfunctional (meth)acrylate monomer (A), an infrared-absorbing component (B), a silicone-based leveling agent (C), and a photopolymerization initiator (D). In this specification, (meth)acrylate includes both acrylate and methacrylate. Furthermore, "PFAS-free" means excluding the intentional incorporation of PFAS into the HC resin composition for the purpose of imparting desired properties, and does not mean the removal of even trace amounts of impurities contained in each component of the HC resin composition.

[0015] The polyfunctional (meth)acrylate monomer (A) used in this invention is a binder for the infrared absorbing component (B) and is also a major component of the film. Examples include (meth)acrylates having functional groups such as aliphatic, alicyclic, polyether skeletons, hydroxyl groups, and amino groups, as well as acrylamide compounds, which can be used alone or in combination of two or more. Examples of oligomers include urethane (meth)acrylate, epoxy (meth)acrylate, polyester (meth)acrylate, polycarbonate (meth)acrylate, acrylic (meth)acrylate, diene (meth)acrylate, etc.

[0016] The above (A) preferably contains an aliphatic chain (meth)acrylate (a1) for the purpose of improving reaction curability. Examples include pentaerythritol triacrylate, pentaerythritol tetraacrylate, dipentaerythritol tetraacrylate, dipentaerythritol pentaacrylate, and dipentaerythritol hexaacrylate (hereinafter referred to as DPHA). Among these, trifunctional or higher is preferred in terms of reactivity, tetrafunctional or higher is more preferred, hexafunctional or higher is particularly preferred, and the inclusion of highly reactive DPHA is most preferred.

[0017] The above (A) preferably contains an alicyclic (meth)acrylate (a2) for the purpose of improving the heat resistance of the cured film and the adhesion to the PC substrate. Examples include dimethylol tricyclodecanediaacrylate, hydrogenated bisphenol A di(meth)acrylate, and alkylene oxide adducts thereof. Among these, dimethylol tricyclodecanediaacrylate is particularly preferred because it has good adhesion to the PC substrate.

[0018] The amount of (A), which is the sum of (a1) and (a2), is preferably 20 to 50% by weight, more preferably 30 to 45% by weight, and particularly preferably 33 to 40% by weight, relative to the total solid content. A concentration of 20% by weight or more ensures sufficient film cohesiveness, while a concentration of 50% by weight or less maintains a good balance between optical properties and infrared absorption performance.

[0019] The amount of (a1) is preferably 5 to 40% by weight, more preferably 10 to 35% by weight, and particularly preferably 15 to 30% by weight, based on the total amount of solids. Similarly, the amount of (a2) is preferably 5 to 40% by weight, more preferably 10 to 35% by weight, and particularly preferably 15 to 30% by weight, based on the total amount of solids. By keeping the amounts within this range, a good balance can be maintained between curability, adhesion to the PC substrate, and infrared absorption performance.

[0020] The blending amount of (a1) with respect to (A) is preferably 15 to 85% by weight, more preferably 20 to 80% by weight, and particularly preferably 25 to 75% by weight. Also, the blending amount of (a2) with respect to (A) is preferably 15 to 85% by weight, more preferably 20 to 80% by weight, and particularly preferably 25 to 75% by weight. By setting it within this range, sufficient curability and adhesion to the PC substrate can be ensured.

[0021] The infrared absorption component (B) used in the present invention mainly selectively absorbs a specific wavelength region in the near-infrared region (750 to 1000 nm), and when blended with a binder, it refers to a component that exhibits a strong absorption and shielding effect against heat. Examples include cesium tungstate, indium tin oxide, antimony tin oxide, lanthanum hexaboride, diimonium salts, and the like. Among these, cesium tungstate, which has a relatively low cost and a high absorption coefficient, is preferred.

[0022] Cesium tungstate strongly absorbs the infrared region particularly at 800 nm to 1200 nm, and is an inorganic nano-particle generally represented by the chemical formula Cs 0.33 WO3. The average particle size is preferably 1 to 50 nm, and more preferably 5 to 35 nm. By setting it within this range, a high visible light transmittance and infrared absorption performance can be maintained in a good balance. Examples of commercially available cesium tungstate-based infrared absorbers include YMF02 (trade name: manufactured by Sumitomo Metal Mining Co., Ltd., average particle size 15 nm, solid content 18.5%). The average particle size can be measured by a particle size distribution measuring device based on the dynamic light scattering method using laser light.

[0023] The blending amount of (B) with respect to the total solid content is preferably 10 to 75% by weight, more preferably 30 to 70% by weight, and particularly preferably 50 to 65% by weight. By setting it at 10% by weight or more, a heat shielding effect due to infrared cut can be obtained, and by setting it at 75% by weight or less, sufficient adhesion to the PC substrate can be ensured.

[0024] The silicone leveling agent (C) used in the present invention is blended for the purpose of improving the leveling characteristics during coating and improving the scratch resistance and water repellency of the cured film. PFAS exhibits the same effects even with a small amount of addition. On the other hand, through repeated trial and error, the applicant found that by including hydroxyl group-containing silicone-modified acrylic as (C), the dispersibility of (B) was significantly improved, a leveling effect equivalent to that of PFAS during coating was obtained, and equivalent optical properties (total light transmittance, haze) were also obtained in the cured film.

[0025] The blending amount with respect to the total solid content of (C) is preferably 0.05 to 3.0% by weight, more preferably 0.1 to 2.0% by weight, and particularly preferably 0.2 to 1.0% by weight. By setting it at 0.05% by weight or more, the appearance after curing can be improved due to the improved leveling property during coating, and by setting it at 3.0% by weight or less, over-addition does not occur and good appearance and optical properties can be ensured.

[0026] The photoinitiator (D) used in the present invention generates radicals upon irradiation with ultraviolet rays, electron beams, etc., and these radicals serve as the trigger for the polymerization reaction, and contains at least an oxime ester type photoinitiator. The oxime ester type is a photoinitiator with extremely high sensitivity, and by including it, it becomes possible to significantly improve the heat-resistant adhesion to the PC substrate. Examples include ethanone, 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazol-3-yl]-, 1-(O-acyloxime), and 1,2-octadiene, 1-[4-(phenylthio)phenyl]-, 2-(o-benzoyloxime), and commercially available products include Irgacure OXE01, OXE02, OXE03, OXE04 (trade name: manufactured by BASF Japan Ltd.), etc.

[0027] Examples of photopolymerization initiators other than oxime esters include benzyl ketal-based, acetophenone-based, and phosphine oxide-based initiators. By arbitrarily selecting the light absorption wavelength of the polymerization initiator, curability can be imparted over a wide wavelength range from the ultraviolet region to the visible light region. Specifically, examples include 2,2-dimethoxy-1,2-diphenylethane-1-one as a benzyl ketal, 1-hydroxycyclohexyl-phenyl-ketone and 1-[4-(2-hydroxyethoxy)-phenyl]-2-hydroxy-2-methyl-1-propane-1-one as α-hydroxyacetophenones, 2-methyl-1-(4-methylthiophenyl)-2-morpholinopropane-1-one as an α-aminoacetophenone, and 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide and bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide as acylphosphine oxides, which can be used individually or in combination of two or more. Among these, it is preferable to include an α-hydroxyacetophenone that is less prone to yellowing, and commercially available products include Omnirad 184 and 2959 (product names: manufactured by BASF Japan, α-hydroxyacetophenone type).

[0028] The ratio of the UV-curing resin component of (D) to 100 parts by weight is preferably 1 to 15 parts by weight, and more preferably 3 to 10 parts by weight. A ratio of 1 part by weight or more allows for good curing properties, while a ratio of 15 parts by weight or less prevents excessive addition, thus preventing yellowing of the coating film and a decrease in shelf life. Furthermore, the ratio of the oxime ester type initiator to the total (D) is preferably 10 to 100% by weight, and more preferably 15 to 100% by weight. This range ensures sufficient heat-resistant adhesion to the PC substrate.

[0029] Preferably, the composition further contains a light stabilizer (E). The inclusion of (E) can reduce the degradation of the cured film due to radiant heat. Examples include a radical scavenger (e1) that efficiently traps alkyl radicals and peroxy radicals generated from polymers photodegraded by ultraviolet light, and an ultraviolet absorber (e2) that suppresses polymer decomposition by converting the absorbed ultraviolet energy into thermal energy.

[0030] Examples of (e1) include hindered amines (hereinafter referred to as HALS), hindered phenols, aromatic amines, etc., which can be used alone or in combination of two or more. Among these, HALS are preferred because they have high radical scavenging efficiency even at low concentrations. The amount of (e1) added is preferably 0.3 to 3.0% by weight, and more preferably 0.5 to 2.0% by weight, relative to the total amount of solids. This range ensures sufficient photostability. Examples of commercially available HALS are Tinuvin 123 and Tinuvin 249 (product name: manufactured by BASF Japan).

[0031] (e2) is a radical chain initiation inhibitor having an absorption band in the high-energy, harmful ultraviolet region, and when used in combination with (e1), it is possible to further improve and stabilize weather resistance. Examples include benzotriazole, triazine, and benzophenone types, which can be used alone or in combination of two or more. Among these, hydroxyphenyltriazine types that can strongly absorb the long-wavelength portion of ultraviolet light are preferred. The amount of (e2) added is preferably 0.05 to 2.0% by weight, and more preferably 0.1 to 1.0% by weight, based on the total amount of solids. By setting it within this range, sufficient ultraviolet absorption characteristics can be ensured. Examples of commercially available hydroxyphenyltriazine types include Tinuvin 460 and 477 (product name: manufactured by BASF Japan).

[0032] Furthermore, the amount of (E), which is the sum of (e1) and (e2), is preferably 0.5 to 5.0% by weight, more preferably 0.8 to 3.0% by weight, and particularly preferably 1.0 to 2.0% by weight, relative to the total amount of solids. An amount of 0.5% by weight or more can be expected to improve weather resistance, while an amount of 5.0% by weight or less avoids excessive blending and ensures sufficient adhesion to the substrate.

[0033] Furthermore, this composition may be used in combination with additives such as monofunctional (meth)acrylate monomers, anti-fingerprint agents, sensitizers, flame retardants, fillers, organic fine particles, inorganic fine particles, dispersants, silane coupling agents, defoamers, antistatic agents, antibacterial agents, antiviral agents, polymerization inhibitors, colorants such as pigments, dyes, and dyes, and plasticizers, as needed, within limits that do not impair its performance.

[0034] To improve the coating properties of this composition on a substrate film, the solid content is diluted with a solvent to 10-70%. Examples of solvents include alcohol-based solvents such as ethanol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, isobutyl alcohol, and diacetone alcohol; ketone-based solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; ester-based solvents such as methyl acetate, butyl acetate, and propylene glycol monomethyl ether acetate; and ether-based solvents such as propylene glycol monomethyl ether (hereinafter referred to as PGM), diethyl ether, and diisopropyl ether. These can be used individually or in combination of two or more types.

[0035] The substrate film used in the HC film of the present invention preferably has a retardation value of 100 nm or less, and more preferably 50 nm or less. Setting it to 100 nm or less makes it less likely for rainbow unevenness to occur in the transmitted and projected image, and also stabilizes the brightness. Note that a retardation value of 100 nm or less for a transparent substrate means that it is 100 nm or less in the thickness direction, width direction, and length direction of the transparent substrate.

[0036] Examples of the above-mentioned base films include acrylic (PMMA) film, polycarbonate film (hereinafter referred to as PC), cycloolefin (co)polymer film, and composite films thereof. Among these, PC film and PMMA / PC composite film are preferred due to their excellent weather resistance, transparency, and flame retardancy. In particular, in the case of composite films, it is preferable to use the PMMA side, which has excellent weather resistance and hardness, on the windshield side, and the PC side, which has excellent heat resistance and mechanical strength, on the image element device side.

[0037] There is no particular requirement for the thickness of the above-mentioned base film, and it can be selected at any time, but 30 to 500 μm is preferred in terms of ease of handling and strength, and 50 to 400 μm is particularly preferred. Commercially available PC films include Carboglass Film (product name: Asahi Glass Co., Ltd.), Panlite Film (product name: Teijin Corporation), and Lexan (product name: SABIC Corporation), while PMMA / PC laminated films include Technoloy (product name: Sumitomo Chemical Co., Ltd.) and Yupiron (product name: Mitsubishi Gas Chemical Corporation).

[0038] The above-mentioned base film can be subjected to surface treatments such as primer treatment, corona treatment, surface roughening treatment by sandblasting or solvent treatment, chromic acid treatment, or surface oxidation treatment by ozone or ultraviolet irradiation treatment, in order to improve adhesion with the composition.

[0039] Methods for applying this composition to a substrate film include known methods such as bar coating, applicator coating, curtain coating, roll coating, gravure coating, reverse coating, comma coating, lip coating, and die coating. While a dry film thickness of 1 to 20 μm is generally exemplified, there are no specific requirements, and the thickness can be selected as needed.

[0040] After applying this composition, it is dried at 60-120°C to evaporate the solvent, and then cured using an ultraviolet irradiation device. Any known light source can be used, such as high-pressure mercury lamps, medium-pressure mercury lamps, low-pressure mercury lamps, metal halide lamps, xenon lamps, LED lamps, or electrodeless ultraviolet lamps. The ultraviolet irradiation condition is 500 mW / cm². 2 ~3,000 mW / cm² 2 With this irradiation intensity, the integrated light dose is 100 mJ / cm². 2 ~2,000 mJ / cm 2 This can be used as an example.

[0041] The present invention will be described in detail below based on examples and comparative examples, but these are merely examples and not limiting. The amounts are given in parts by weight, and unless otherwise specified, measurements were taken under conditions of 25°C and 65% relative humidity. [Examples]

[0042] Examples In a light-shielding bottle, (a1) DPHA (dipentaerythritol hexaacrylate), (a2) DCP-A (product name: manufactured by Kyoeisha Chemical Co., Ltd., dimethylol-tricyclodecane diacrylate), (B) YFM02A (product name: manufactured by Sumitomo Metal Mining Co., Ltd., solids content 28.4% by weight, cesium tungsten oxide content 18.5% by weight), and (C) SILCLEAN 3700 (product name: BYK, hydroxyl group-containing silicone-modified acrylic, solids content 25% by weight) was used as (d1) IrgacureOxe04 (product name: BASF Japan, oxime ester type), (d2) Omnirad2959 (product name: BASF Japan, α-hydroxyacetophenone type), (e1) Tinuvin249 (product name: BASF Japan, solids content 100% by weight, HALS type), and (e2) Tinuvin477 (product name: BASF Japan, solids content 80% by weight, hydroxyphenyltriazine type). The amounts shown in Table 1 were added, diluted with PGM to a solids content of 45% by weight, and stirred for 15 minutes or more using a stirring and degassing machine until homogeneous to prepare the infrared-cutting hard coat resin composition of the example.

[0043] Comparative Example In addition to the materials used in the examples, the following silicone-based leveling agents were used: SILCLEAN 3720 (product name: BYK Corporation, hydroxyl group-containing polyalkylsiloxane, solids content 25% by weight), BYK-322 (product name: BYK Corporation, aralkyl-modified polysiloxane, solids content 100% by weight), BYK-349 (product name: BYK Corporation, polyether-modified polysiloxane, solids content 100% by weight), and X-71-1203M (product name: Shin-Etsu Chemical Co., Ltd., fluorine-based leveling agent, solids content 20% by weight). The amounts shown in Table 2 were added, diluted with PGM to a solids content of 45% by weight, and stirred for at least 15 minutes using a stirring and degassing machine until homogeneous to prepare the infrared-cut hard coat resin composition of the comparative example. Comparative Example 5 is a comparative (reference) example using PFAS.

[0044] Table 1 JPEG2026109793000001.jpg109135

[0045] Table 2 JPEG2026109793000002.jpg110135

[0046] Hard coat film creation An infrared-cutting hard coat resin composition was applied to the PMMA side of a Yupiron DF02U (product name: manufactured by Mitsubishi Gas Chemical Co., Ltd., PMMA / PC composite film, thickness 375 μm, retardation value less than 50 nm) to a dry film thickness of 3 μm. After drying in a constant temperature bath at 80°C for 1 minute, ultraviolet irradiation was performed using a metal halide lamp at an output of 1,000 mW / cm2 and an integrated light amount of 150 mJ to create an infrared-cutting hard coat film.

[0047] The evaluation method was as follows:

[0048] Appearance: The appearance of the hard coat film described above was visually inspected. A circle (○) indicated a uniform coating, while a cross (×) indicated defects such as orange peel texture, white haze, or streaks.

[0049] Total light transmittance: The above hard coat film was measured using a Haze-GARD2 haze meter manufactured by Toyo Seiki Seisakusho in accordance with JIS K7361-1. The evaluation was as follows: over 80% was marked with ◎, 78-80% with ○, and less than 78% with ×.

[0050] Haze: The above hard coat film was measured using a HAZE-GARDi haze meter manufactured by Vic Gardner in accordance with JIS K7136. The evaluation method was as follows: less than 0.8% was marked with ◎, 0.8 to 1.1% with ○, and more than 1.1% with ×.

[0051] Pencil hardness was measured using a pencil scratch coating hardness tester (model P) manufactured by Toyo Seiki Seisakusho Co., Ltd., under a 500g load, in accordance with JIS K5600-5-4 (1999 edition). The evaluation method was as follows: ◎ for above 4H, ○ for 3H to 4H, and × for below 3H.

[0052] Heat-resistant adhesion: The hard coat film was placed in a constant temperature bath at 85°C for 24 hours, then returned to room temperature before evaluating its adhesion and checking the degree of delamination of the coating. When cellophane tape attached to the coating was peeled off, a score of ◎ was given if 0 squares were peeled off, a score of ○ was given if fewer than 10 squares were peeled off, and a score of × was given if 10 to 99 squares were peeled off.

[0053] Evaluation results Table 3 JPEG2026109793000003.jpg80135

[0054] Table 4 JPEG2026109793000004.jpg81135

[0055] Each of the infrared-cutting hard coat films in the example and comparative example 5 containing PFAS obtained good results in all evaluation items, including appearance, total light transmittance, haze, pencil hardness, and heat adhesion resistance.

[0056] On the other hand, Comparative Example 1, which did not contain the oxime ester type, had poor heat resistance and adhesion, and Comparative Examples 2 to 4, which differed in (C), all had poor appearance and high haze, and none of them were suitable for the present invention.

Claims

1. An infrared-cutting hard coat resin composition comprising a polyfunctional (meth)acrylate monomer (A), an infrared-absorbing component (B), a silicone-based leveling agent (C), and a photopolymerization initiator (D), wherein (C) contains a hydroxyl group-containing silicone-modified acrylic, and (D) contains an oxime ester type.

2. The infrared-cutting hard coat resin composition according to claim 1, further characterized by containing a stabilizer (E).

3. A hard coat film having a cured layer of the infrared-cutting hard coat resin composition according to claim 1 or 2.

4. A head-up display device using the hard coat film described in claim 3.

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