Hard coat resin composition and hard coat film

Abstract

To provide a hard coat (HC) resin and a HC film featuring sufficiently good appearance as a HC film, as well as high pencil hardness and superior scratch resistance.SOLUTION: A hard coat resin composition comprises: a binder resin having a polymerizable functional group; inorganic nano fine particles surface-modified with an organic compound containing a polymerizable unsaturated group; a leveling agent; and a photopolymerization initiator, wherein the inorganic nano fine particles include silica fine particles and alumina fine particles.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a photocurable hard coat resin composition and a hard coat film using the same.

Background Art

[0002] Acrylic photocurable resins are used in many fields to impart functionality to the surfaces of plastic films and plastic moldings. For example, a hard coat (hereinafter referred to as HC) film having high hardness by coating on a PET (polyethylene terephthalate) film is widely used as a film for touch panels and a film for molding.

[0003] Particularly, in the case of touching the image display surface with a finger or inputting with a touch pen as in a touch panel, higher hardness and excellent scratch resistance are required. A method of blending inorganic fillers such as silica and alumina is known to make the hard coat layer have high hardness. For example, in the past, the applicant has proposed a composition containing a polyfunctional (meth) acrylate oligomer having six or more (meth) acryloyl groups obtained by reacting specific components and nano fine particles composed of alumina particles or silica particles as a resin for an HC film excellent in hardness, abrasion resistance, and moldability (Patent Document 1).

[0004] This composition had a balance between pencil hardness and scratch resistance, and also had a high elongation at break and excellent moldability. However, it could not be said that the pencil hardness and scratch resistance sufficiently reached the levels required by the market. Therefore, there was room for improvement to obtain a sufficient appearance as an HC film and to further improve the HC film to have higher hardness and excellent scratch resistance.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] The problem of the present invention is to provide an HC resin and an HC film that have a sufficient appearance as an HC film and have a high pencil hardness and excellent scratch resistance.

Means for Solving the Problems

[0007] In order to solve the above problems, the invention of claim 1 according to the present application includes a binder resin (A) having a polymerizable functional group, inorganic nano fine particles (B) surface-modified with an organic compound containing a polymerizable unsaturated group, a leveling agent (C), and a photopolymerization initiator (D), and the (B) includes silica fine particles (b1) and alumina fine particles (b2), and provides a hard coat resin composition.

[0008] The invention of claim 2 provides the hard coat resin composition according to claim 1, wherein the average particle diameter of the (b1) is 5 to 50 nm and the average particle diameter of the (b2) is 10 to 100 nm.

[0009] The invention of claim 3 provides the hard coat resin composition according to claim 1, wherein the blending amount of the (B) is 5 to 90 parts by weight with respect to 100 parts by weight of the (A).

[0010] The invention of claim 4 provides a hard coat film having a cured layer of the hard coat resin composition according to any one of claims 1 to 3 on a transparent plastic substrate.

Effects of the Invention

[0011] The resin composition of the present invention has an excellent appearance after being coated on a film and has a high pencil hardness and excellent scratch resistance, and is therefore useful as an HC resin for an HC film.

Modes for Carrying Out the Invention

[0012] The present invention will be described in detail.

[0013] The HC resin composition of the present invention contains a binder resin (A) having a polymerizable functional group, inorganic nanoparticles (B), a leveling agent (C), and a photopolymerization initiator (D). In this specification, (meth)acrylate includes both acrylate and methacrylate.

[0014] The binder resin (A) having a polymerizable functional group used in the present invention disperses the inorganic nanoparticles (B) and is a main component constituting the HC resin. There is no particular limitation on the (A) used, and examples include radical polymerization-based acrylic resin binders and cationic polymerization-based epoxy resin binders. Among these, acrylic resin binders are preferred in terms of curing speed. Examples of oligomers of acrylic resin binders include urethane (meth)acrylate (hereinafter referred to as ureac), epoxy (meth)acrylate, polyester (meth)acrylate, polycarbonate (meth)acrylate, acrylic (meth)acrylate, diene (meth)acrylate, etc., and they can be used alone or in combination of two or more.

[0015] As a component other than the oligomer, a low molecular weight binder may be used. For example, (meth)acrylates having functional groups such as aliphatic, alicyclic, polyether skeletons, hydroxyl groups and amino groups, and acrylamide compounds can be mentioned, and they can be used alone or in combination of two or more. In terms of the number of functional groups, it is preferably polyfunctional in terms of reactivity. For example, in the case of difunctional, ethylene glycol di(meth)acrylate, (poly)ethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, (poly)propylene glycol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate and the like can be mentioned. In the case of trifunctional or more, pentaerythritol triacrylate, trimethylolpropane triacrylate, pentaerythritol tetraacrylate, dipentaerythritol pentaacrylate (hereinafter referred to as DPPA), dipentaerythritol hexaacrylate (hereinafter referred to as DPHA) and the like can be mentioned.

[0016] The blending ratio with respect to the total solid content of the above (A) is preferably 45 to 90% by weight, more preferably 60 to 88% by weight, and particularly preferably 70 to 87% by weight. By setting it to 45% by weight or more, sufficient scratch resistance can be ensured, and by setting it to 90% by weight or less, curling can be suppressed and sufficient pencil hardness can be ensured.

[0017] The inorganic nanoparticles (B) used in the present invention are blended for the purpose of obtaining high pencil hardness. (B) is surface-modified with an organic compound containing a polymerizable unsaturated group capable of polymerizing with (A), and includes silica fine particles (b1) and alumina fine particles (b2). When (b1) and (b2) are not used in combination, the pencil hardness may decrease. In particular, when (b2) is blended alone, the refractive index increases and rainbow unevenness and the like are likely to occur.

[0018] As the polymerizable unsaturated group capable of undergoing a polymerization reaction for modifying the surface of (B), it is preferably the same functional group as (A), and a (meth)acryloyl group is preferred in terms of reactivity. When using nano-particles without surface treatment instead, the dispersibility decreases, and when applied to a film, there are many lumps due to secondary aggregation, and the appearance tends to deteriorate. Also, when the surface is subjected to a hydrophobic treatment with no reactivity, the pencil hardness tends to decrease.

[0019] The blending ratio with respect to the total solid content of (B) is preferably 5 to 50% by weight, more preferably 8 to 45% by weight, and particularly preferably 10 to 25% by weight. By setting it at 5% by weight or more, sufficient pencil hardness can be ensured, and by setting it at 50% by weight or less, sufficient abrasion resistance can be ensured.

[0020] The silica fine particles (b1) contained in (B) improve the surface hardness by suppressing the detachment from the coating film surface because the functional groups on the silica surface strongly bond to the functional groups of (A). The average particle diameter is preferably 5 to 50 nm, more preferably 10 to 40 nm, and particularly preferably 12 to 35 nm. By setting it at 5 nm or more, sufficient pencil hardness can be ensured, and by setting it at 50 nm or less, sufficient total light transmittance can be ensured. The average particle diameter is the median diameter (d = 50) measured by the laser diffraction / scattering method in accordance with JIS Z8825-1.

[0021] The blending ratio of (b1) in (B) is preferably 20 to 80% by weight, more preferably 40 to 60% by weight. Also, the blending ratio with respect to the total solid content is preferably 2 to 30% by weight, more preferably 3 to 25% by weight. Examples of commercially available (b1) include PGM-AC-2140Y (trade name: manufactured by Nissan Chemical Industries, Ltd., solid content 42% by weight, average particle diameter 12 nm) and SIRPGM30WT%-H55 (trade name: manufactured by CIK Nanotech Co., Ltd., solid content 30% by weight, average particle diameter 30 nm).

[0022] The alumina fine particles (b2) used in the present invention, like (b1), have functional groups on the surface of the alumina fine particles firmly bonded to the functional groups of (A), so that the peeling from the coating film surface is suppressed, thereby improving the surface hardness. The average particle size is preferably 10 to 100 nm, more preferably 20 to 90 nm, and particularly preferably 25 to 85 nm. By setting it to 10 nm or more, sufficient pencil hardness can be ensured, and by setting it to 100 nm or less, sufficient total light transmittance can be ensured without increasing the haze.

[0023] The blending ratio of (b2) in (B) is preferably 20 to 80% by weight, and more preferably 40 to 60% by weight. Also, the blending ratio based on the total solid content is preferably 2 to 30% by weight, and more preferably 3 to 25% by weight. Examples of commercially available (b2) include ALMIBK-M47 (trade name: manufactured by CIK Nanotech Co., Ltd., solid content 30%, average particle size 30 nm) and ALMIBK-N13 (trade name: manufactured by CIK Nanotech Co., Ltd., solid content 30%, average particle size 80 nm).

[0024] The leveling agent (C) used in the present invention is blended for the purpose of improving the leveling property during coating to stabilize the surface appearance, and at the same time improving the slip property of the HC layer to improve the wear resistance. For example, silicone-based, fluorine-based, acrylic-based, etc. can be mentioned. It is preferable to have a reactive functional group that can polymerize with (A) and (B) to form a cured coating film in that it can maintain the effect for a long time without dropping out over time due to bleeding or the like from the cured film. In particular, fluorine-based silicone compounds are preferable in that they are likely to segregate on the coating film surface after coating to drying due to their low surface free energy, and can stabilize the wear resistance and antifouling property over a long period.

[0025] The compounding amount with respect to the total solid content of (C) is preferably 0.05 to 3.0% by weight, more preferably 0.1 to 1.0% by weight, and particularly preferably 0.2 to 0.5% by weight. By setting it at 0.05% by weight or more, it is expected to improve the leveling property and abrasion resistance, and by setting it at 3.0% by weight or less, sufficient curability can be ensured. As a commercially available product, X-71-1203M (trade name: manufactured by Shin-Etsu Chemical Co., Ltd., solid content 20%, fluorine-based silicone compound having reactive functional groups) can be mentioned.

[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. General-purpose photoinitiators such as benzyl ketal-based, acetophenone-based, and phosphine oxide-based can be used. By arbitrarily selecting the light absorption wavelength of the photoinitiator, curability can be imparted over a wide wavelength range from the ultraviolet region to the visible light region. Specifically, 2,2-dimethoxy-1,2-diphenylethane-1-one as a benzyl ketal-based, 1-hydroxy-cyclohexyl-phenyl-ketone and 1-[4-(2-hydroxyethoxy)-phenyl]-2-hydroxy-2-methyl-1-propan-1-one as an α-hydroxyacetophenone-based, 2-methyl-1-(4-methylthiophenyl)-2-morpholinopropan-1-one as an α-aminoacetophenone-based, 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide and bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide as an acylphosphine oxide-based, etc. are available, and they can be used alone or in combination of two or more. Among these, it is preferable to contain an α-hydroxyacetophenone-based which is less likely to cause yellowing. As commercially available products, there are Omnirad 184 and the same 2959 (trade name: manufactured by iGM Co., Ltd., α-hydroxyacetophenone-based), etc.

[0027] The ratio to 100 parts by weight of the photocurable resin component (D) is preferably 0.5 to 10 parts by weight, more preferably 2 to 8 parts by weight. By setting it to 0.5 parts by weight or more, sufficient curability can be exhibited, and by setting it to 10 parts by weight or less, over-addition can be avoided, and yellowing of the coating film and deterioration of storage stability can be prevented.

[0028] In addition, an ultraviolet absorber, an antioxidant, a colorant, an antifoaming agent, a thickener, a precipitation inhibitor, an antistatic agent, an antifogging agent, an antibacterial agent, an antiviral agent, organic fine particles, etc. may be added to the hard coat resin of the present invention as needed.

[0029] The HC resin composition of the present invention may be diluted with a solvent so that the solid content is 10 to 70% in order to improve the coatability on the substrate. Examples of the solvent include alcohol solvents such as ethanol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, isobutyl alcohol, and diacetone alcohol, ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone, ester solvents such as methyl acetate and butyl acetate, and ether solvents such as propylene glycol monomethyl ether, diethyl ether, and diisopropyl ether. These can be used alone or in combination of two or more.

[0030] Examples of the transparent plastic substrate to which the HC resin composition of the present invention is applied include PET film, polyethylene film, polypropylene film, diacetyl cellulose film, triacetyl cellulose film, acetyl cellulose butyrate film, polyvinyl chloride film, polyvinylidene chloride film, polyvinyl alcohol film, ethylene vinyl alcohol film, polystyrene film, polycarbonate film, polymethylpentene film, polysulfone film, polyetheretherketone film, polyethersulfone film, polyetherimide film, polyimide film, fluororesin film, nylon film, acrylic film, cycloolefin (co)polymer film, and the like. Among these, a biaxially stretched PET film is preferably used from the viewpoints of price, processability, dimensional stability, etc. The thickness of the film is not particularly limited, and for example, 23 μm to 250 μm can be exemplified.

[0031] The method for applying the HC resin composition of the present invention is not particularly limited, and known coating methods such as spray coating, roll coating, die coating, air knife coating, blade coating, spin coating, reverse coating, gravure coating, wire bar, etc. or gravure printing, screen printing, offset printing, inkjet printing, etc. can be used. The dry film thickness is preferably 0.5 μm to 10 μm.

[0032] After applying the HC resin composition of the present invention, it is dried at 60 to 120 °C and cured using an ultraviolet irradiation machine. Examples of the light source when irradiating ultraviolet rays include low-pressure mercury lamps, high-pressure mercury lamps, ultra-high-pressure mercury lamps, carbon arc lamps, xenon lamps, metal halide lamps, electrodeless ultraviolet lamps, etc. The curing conditions are an irradiation intensity of 500 mW / cm 2 ~3000 mW / cm 2 and an integrated light amount of 50 to 2,000 mJ / cm 2 are exemplified. The atmosphere for irradiation may be in air or in an inert gas such as nitrogen or argon.

[0033] Hereinafter, the present invention will be described in detail based on examples and comparative examples. However, these are merely specific examples and are not particularly limited thereto. When there is no notation, the measurement was carried out under the conditions of room temperature of 25°C and relative humidity of 65%. The blending amounts are shown in parts by weight in terms of solid content.

Examples

[0034] Example 1 (A) is DPHA (trade name: manufactured by Nippon Kayaku Co., Ltd., a mixture of DPPA and DPHA), (b1) is SIRPGM30WT%-H55 (trade name: manufactured by CIK Nanotech Co., Ltd., average particle size 30 nm, methacryl-modified silica, solid content 30% by weight), (b2) is ALMIBK30WT%-M47 (trade name: manufactured by CIK Nanotech Co., Ltd., average particle size 30 nm, methacryl-modified alumina, solid content 30% by weight), (C) is X-71-1203M (trade name: manufactured by Shin-Etsu Chemical Co., Ltd., solid content 20%, fluorine-based silicone compound having reactive functional groups), (D) is Omnirad2959 (trade name: manufactured by iGM Co., Ltd.). MEK was blended as a diluting solvent so that the solid content became 30%, and the mixture was stirred until it was uniformly dissolved and dispersed in the formulation described in Table 1 to prepare Example 1, which is an HC resin composition.

[0035] Examples 2 to 6 In addition to the materials used in Example 1, (b1) is PGM-AC-2140Y (trade name: manufactured by Nissan Chemical Industries, Ltd., average particle size 20 nm, methacryl-modified silica, PGM dispersion, solid content 42% by weight), (b2) is ALMIBK30WT%-N13 (trade name: manufactured by CIK Nanotech Co., Ltd., average particle size 80 nm, methacryl-modified alumina, solid content 30% by weight). MEK was blended as a diluting solvent so that the solid content became 30%, and the mixture was stirred until it was uniformly dissolved and dispersed in the formulation described in Table 1 to prepare Examples 2 to 6, which are HC resin compositions.

[0036] Comparative Examples 1 to 5 In addition to the materials used in the examples, MEK-ST-L (trade name: manufactured by Nissan Chemical Industries, Ltd., average particle diameter 45 nm, MEK-dispersed, solid content 30% by weight) was used as surface-untreated silica fine particles, and NANOBYK-3611 (trade name: manufactured by BYK, average particle diameter 20 nm, solid content 30% by weight) was used as surface-untreated alumina fine particles. MEK was blended as a diluting solvent so that the solid content was 30%, and stirring was carried out until uniform dissolution and dispersion were achieved with the formulation described in Table 2, to prepare Comparative Examples 1 to 5 of the HC resin composition.

[0037] Adjustment of HC film Two types were coated on a 75U403 PET film (trade name: manufactured by Toray Industries, Inc., 75 μm, with easy-adhesion layers on both sides) of A4 size so that the film thickness during curing would be 5 μm and 10 μm. After drying at 80 °C for 1 minute in a constant-temperature bath, ultraviolet curing was performed using an electrodeless UV irradiation device F300S / LC-6B manufactured by Fusion UV Systems Japan with an output of 1300 mW / cm2 and an integrated light quantity of 150 mJ / cm2 using an H bulb.

[0038] Table 1 JPEG2025091849000001.jpg85135

[0039] Table 2 JPEG2025091849000002.jpg116162

[0040] The evaluation method was as follows.

[0041] Pencil hardness: Using the HC film (coated with 10 μm) adjusted above, in accordance with JIS K5600-5-4 (1999 edition), measurement was carried out at a load of 750 g using a pencil scratch film hardness tester (model P) manufactured by Toyo Seiki Seisakusho. The evaluation was based on the hardness at which no more than 3 scratches occurred, with 5H being ◎, 4H being ○, and less than 4H being ×.

[0042] Scratch resistance: Using the HC film (coated with 10 μm) adjusted above, on a steel wool #0000 with a contact area of φ25 mm in diameter, a load of 2000 g was placed on a wear tester manufactured by Toyo Seiki Co., Ltd., and it was reciprocated 100 times and 1000 times at a reciprocating speed of 100 times / min. The presence or absence of scratches was confirmed by visual observation. When there were no scratches, it was marked as ○, and when scratches were present, the number was confirmed. The evaluation was marked as ◎ when there were no scratches after 1000 reciprocations, ○ when there were no scratches after 100 reciprocations, and × when there were scratches after 100 reciprocations.

[0043] Rainbow unevenness: A black PTE film was laminated on the back surface of the HC film (coated with 10 μm), and when visually confirmed at an angle of 45° facing directly below an LED-type fluorescent lamp, when there was no occurrence of rainbow unevenness, it was marked as ○, and when there was, it was marked as ×.

[0044] Curling resistance: Using the HC film (coated with 5 μm), a film cut to a size of 100 mm × 100 mm was placed on a flat plate, and the average value of the warping at the four ends was measured. The evaluation was marked as ◎ when the average value was less than 20 mm, ○ when it was less than 20 - 24 mm, and × when it was 24 mm or more.

[0045] Results of the examples JPEG2025091849000003.jpg72135

[0046] Results of the comparative examples JPEG2025091849000004.jpg98158

[0047] In the examples, there were no problems in terms of pencil hardness, scratch resistance, rainbow unevenness, and curling resistance, and the results were good.

[0048] On the other hand, in Comparative Example 1 where (b1) was not blended, rainbow unevenness occurred. In Comparative Example 2 where non-reactive alumina was blended instead of (b2), and in Comparative Example 3 where non-reactive silica was blended instead of (b1), the pencil hardness was low in both cases. Also, in Comparative Example 4 where (C) was removed, the scratch resistance was inferior, and in Comparative Example 5 where (B) was removed, the pencil hardness was low and the warping was large, and none of them were suitable for the invention of the present application. ​

Claims

1. A hard coat resin composition comprising a binder resin (A) having a polymerizable functional group, inorganic nanoparticles (B) surface-modified with an organic compound containing a polymerizable unsaturated group, a leveling agent (C), and a photopolymerization initiator (D), wherein the (B) contains silica fine particles (b1) and alumina fine particles (b2).

2. The hard coat resin composition according to claim 1, wherein the average particle diameter of the (b1) is 5 to 50 nm, and the average particle diameter of the (b2) is 10 to 100 nm.

3. The hard coat resin composition according to claim 1, wherein the blending amount of the (B) is 5 to 90 parts by weight with respect to 100 parts by weight of the (A).

4. A hard coat film having a cured layer of the hard coat resin composition according to any one of claims 1 to 3 on a transparent plastic substrate.

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