Photocurable resin composition, hard coat film, and plastic molded article using the same

Abstract

To provide a photocurable resin composition suitable for molding operations including insert molding, having high elongation at break and high moldability as well as superior wear resistance and chemical resistance, and a hard coat film and a plastic molding including the photocurable resin composition.SOLUTION: A photocurable resin composition comprises: a urethane methacrylate oligomer, which is a product from the reaction of an ethylene glycol, an isophorone diisocyanate, and a polyfunctional methacrylate having a glycerol skeleton; and a photopolymerization initiator.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a photocurable resin composition, a hard coat film having a cured resin layer thereof, and a plastic molded article using the same. [Background technology]

[0002] Acrylic photocurable resins are used in many fields to impart special properties to the surfaces of plastic films and plastic moldings. For example, hard-coated films, which are applied to PET (polyethylene terephthalate) films to impart high hardness, are used in large quantities as films for touch panels and molding films.

[0003] Among these, insert films are well known for use in molding. A design is printed on the film surface, and then the film is softened by heating and molded into a three-dimensional shape. However, if the hard coat resin layer applied to the film is hardened, microcracks tend to form on the curved surface when the film is processed into a three-dimensional shape, limiting the shape that can be processed. For this reason, the applicant previously invented a hard coat agent containing a triazine ring-containing (meth)acrylate prepolymer and organic fine particles with an average primary particle diameter of 80 to 500 nm as a hard coat resin for insert molding that combines surface hardness and moldability (Patent Document 1). This hard coat agent was excellent, achieving both sufficient flexibility and surface properties at a film thickness of 1 to 10 μm.

[0004] While selecting hard coating agents suitable for these molding applications has alleviated some of the processing constraints, they may still lack elongation in applications requiring deep drawing, and in applications where they are frequently touched by hands, such as in the field of automobile interiors, there is the issue that hand cream on the surface of the hands can attack the hard coating surface film, causing it to peel off over long periods of use. Furthermore, in recent years, concerns about the depletion of petroleum resources and the problem of increased carbon dioxide in the air, which causes global warming and climate change, have led to a great deal of attention being paid to biomass resources, which do not rely on petroleum resources as raw materials and are carbon-neutral, meaning that they do not increase carbon dioxide when burned. In addition to the properties of achieving both good processing properties (elongation) and chemical resistance, there is also a growing demand for biomass-based hard coating agents themselves. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 4848200 Summary of the Invention [Problem to be solved by the invention]

[0006] An object of the present invention is to provide a photocurable resin composition that has high breaking elongation and good moldability, as well as excellent abrasion resistance and chemical resistance, and is suitable for molding applications such as insert molding, and to provide a molding hard coat film and a plastic molded product using the same. [Means for solving the problem]

[0007] In order to solve the above problem, the invention of claim 1 is as follows: A diisocyanate obtained by reacting only ethylene glycol and isophorone diisocyanate is further treated with glycerin polyfunctional (meth)acrylate (a1). The present invention provides a photocurable resin composition comprising a reacted urethane (meth)acrylate oligomer (A) and a photopolymerization initiator (B).

[0008] A second aspect of the present invention provides the photocurable resin composition according to the first aspect, wherein the (a1) is a biomass (meth)acrylate using plant-derived raw materials.

[0009] The invention of claim 3 provides the photocurable resin composition according to claim 1 or 2, further comprising an antiviral agent (C).

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

[0011] The invention of claim 5 is the same as that of claim 4. A hard coat film for molding, characterized in that the plastic substrate is a biomass polycarbonate film. to provide. [Effects of the Invention]

[0012] The photocurable resin composition of the present invention has high breaking elongation and good moldability, as well as excellent abrasion resistance and chemical resistance, and is useful as a hard coat resin to be applied to molding films used in insert molding and the like. BEST MODE FOR CARRYING OUT THE INVENTION

[0013] The photocurable resin composition of the present invention is formed by reacting ethylene glycol and isophorone diisocyanate (hereinafter referred to as IPDI). Respond The diisocyanate thus obtained is further reacted with a polyfunctional (meth)acrylate (a1) having a glycerin skeleton to form a urethane (meth)acrylate (A), and a photopolymerization initiator (B). In this specification, the term "(meth)acrylate" encompasses both acrylate and methacrylate.

[0014] The polyfunctional (meth)acrylate (a1) having a glycerin skeleton used in the synthesis of (A) is preferably a biomass (meth)acrylate. For example, it may be an ester compound of plant-derived (poly)glycerin and (meth)acrylic acid. Compared to non-biomass, petroleum-derived polyfunctional glycerin (meth)acrylates, it has high sensitivity and reactivity, and the cured coating tends to have high hardness and excellent abrasion resistance.

[0015] Examples of the (a1) include: Glycerin di(meth)acrylate, diglycerin di(meth)acrylate, diglycerin tri(meth)acrylate, etc. These can be used alone or in combination of two or more. Of these, glycerin diacrylate (hereinafter referred to as GDA) is preferred because it is readily available, has relatively little shrinkage on cure, and produces a cured film with high hardness and good scratch resistance.

[0016] In addition, the alicyclic diisocyanate IPDI used in the synthesis of (A) does not yellow and has excellent weather resistance, while also being highly rigid, allowing for increased hardness of the cured product. Reacting it with ethylene glycol, which has a very short carbon chain, increases the concentration of urethane bonds within the molecule, forming a highly rigid, linear main skeleton with excellent chemical resistance. Using polyethylene glycol (hereinafter referred to as PEG) instead of ethylene glycol tends to decrease the concentration of urethane bonds, resulting in reduced fabric abrasion resistance and chemical resistance.

[0017] The synthesis method for (A) is not particularly limited, and known methods can be used. The reaction can be carried out without a solvent. However, as the molecular weight of (A) increases, stirring can become difficult. Therefore, ketones such as butanone, aromatic inert solvents such as xylene, etc., can be used. Furthermore, it is preferable to use a catalyst for the reaction between the hydroxyl groups of ethylene glycol and (a1) and the isocyanate groups. Examples of such a catalyst include tin-based catalysts such as dibutyltin dilaurate and metal alkoxide-based catalysts such as cobalt naphthenate. The reaction temperature can be set as appropriate, but is preferably 40 to 120°C, more preferably 60 to 100°C.

[0018] The Mw of (A) is preferably 1,500 to 30,000, more preferably 2,000 to 15,000, and particularly preferably 3,000 to 10,000. A Mw of 1,500 or more ensures sufficient elongation at break, while a Mw of 30,000 or less facilitates adjustment to a viscosity that is easy to work with. The Mw of (A) can be adjusted by the molar ratio of ethylene glycol and IPDI to be reacted; the closer the molar ratio of IPDI to ethylene glycol, the higher the Mw tends to be. The Mw was measured and calculated by gel permeation chromatography using a column packed with a styrene-divinylbenzene base material and a tetrahydrofuran eluent, relative to standard polystyrene.

[0019] The blending amount of (A) is preferably 60 to 99% by weight, more preferably 70 to 98% by weight, and particularly preferably 75 to 97% by weight, based on the total solid content. By making it 60% by weight or more, sufficient breaking strength can be ensured, and by making it 99% by weight or less, sufficient curability can be ensured.

[0020] The photopolymerization initiator (B) used in the present invention generates radicals upon irradiation with ultraviolet light or an electron beam, and these radicals trigger the polymerization reaction, and general-purpose photopolymerization initiators such as benzyl ketals, acetophenones, and phosphine oxides can be used. By arbitrarily selecting the light absorption wavelength of the polymerization initiator, it is possible to impart curability over a wide wavelength range from the ultraviolet region to the visible light region. Specifically, benzyl ketals include 2,2-dimethoxy-1,2-diphenylethan-1-one, α-hydroxyacetophenones include 1-hydroxy-cyclohexyl-phenyl-ketone and 1-[4-(2-hydroxyethoxy)-phenyl]-2-hydroxy-2-methyl-1-propan-1-one, α-aminoacetophenones include 2-methyl-1-(4-methylthiophenyl)-2-morpholinopropan-1-one, and acylphosphine oxides include 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide and bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide, which can be used alone or in combination of two or more.

[0021] Among these, it is preferable to use an α-hydroxyacetophenone-based resin that is less prone to yellowing, and examples of commercially available products include Omnirad 127, 184, and 2959 (trade names: manufactured by IGM Resins Co., Ltd.) The amount of (B) added per 100 parts by weight of the radically polymerizable component is preferably 0.5 to 10 parts by weight, more preferably 1 to 8 parts by weight.

[0022] The composition of the present invention may further contain an antiviral agent (C). (C) generally has antiviral properties and includes inorganic compounds containing copper, silver, titanium, tin, iron, nickel, zinc, etc., as well as organic materials such as quaternary ammonium salt compounds, hydroxyapatite, and polymers containing sulfonic acid groups or their salts. However, the manifestation of antiviral properties varies greatly depending on the manufacturing process and the combination with the binder. Furthermore, the addition of antiviral agents may cause changes in appearance, such as increased haze or coloration, so it is necessary to select an antiviral agent that is appropriate for the intended product. Quaternary ammonium-based agents are preferred for (A) of the present invention because of their compatibility and good antiviral properties.

[0023] The blending amount of (C) is preferably 1.0 to 10.0% by weight, more preferably 3.0 to 8.0% by weight, based on the total solid content. A blending amount of 1.0% by weight or more ensures sufficient antiviral properties, while a blending amount of 10.0% by weight or less ensures sufficient elongation at break. Commercially available products include Suranimo D100 (trade name: manufactured by Osaka Gas Chemicals Co., Ltd.) and Marukaside V-1 (trade name: manufactured by Osaka Kasei Co., Ltd.).

[0024] To the composition of the present invention, reactive diluents, surface conditioners, ultraviolet absorbers, adhesion promoters, antioxidants, bluing agents, pigments, defoamers, thickeners, anti-precipitation agents, antistatic agents, anti-fogging agents, antibacterial agents, waxes, matting agents, hydrophilic agents, water-repellent agents, inorganic fillers, organic fine particles, and the like may be added as needed, provided that the performance is not impaired.

[0025] The reactive diluent is blended to reduce viscosity and improve reactivity. A (meth)acrylate monomer is preferred, with a polyfunctional (meth)acrylate being even more preferred. Blending a large amount of monofunctional (meth)acrylate alone tends to result in a cured product with a low molecular weight and a low elongation at break and chemical resistance. The blending amount is preferably 25% by weight or less, more preferably 15% by weight or less, based on the total solid content. By blending an amount of 25% by weight or less, sufficient elongation at break can be ensured without excessive curing. Trifunctional or higher functional diluents are particularly preferred, as they improve reactivity even with small additions. Examples include pentaerythritol triacrylate (hereinafter referred to as PET3A), pentaerythritol tetraacrylate, and dipentaerythritol hexaacrylate (hereinafter referred to as DPHA). These can be used alone or in combination of two or more.

[0026] The surface conditioner is added to improve the appearance and slipperiness of the cured product surface, thereby reducing the coefficient of friction and thereby improving fabric abrasion resistance. Examples include polyether-modified polydimethylsiloxane, polyester-modified polydimethylsiloxane, aralkyl-modified polymethylalkylsiloxane, modified polyether, and fluorine-based polymers, which can be used alone or in combination of two or more. Among these, polydimethylsiloxane copolymers with polyether groups introduced into the side chains and fluorine-based polymers are preferred, as they have good compatibility with (A) and are highly effective even with a small amount added.

[0027] The amount of the surface conditioner is preferably 0 to 3.0% by weight, more preferably 0.3 to 2.0% by weight, based on the total solid content. Amounts of 0.3% or more ensure sufficient appearance and abrasion resistance, while amounts of 3.0% by weight or less ensure sufficient elongation at break without excessive addition. Commercially available products include BYK-UV3500 (product name: BYK, silicone-based) and KY-1203 (product name: Shin-Etsu Chemical Co., Ltd., fluorosilicone-based).

[0028] The inorganic filler is blended to increase the hardness of the cured coating. Examples include silica and alumina, which can be used alone or in combination of two or more. The average particle size is preferably 1 to 200 nm, more preferably 5 to 100 nm, and particularly preferably 10 to 80 nm. By keeping the average particle size within this range, it is expected that the hardness of the cured coating will be improved without significantly affecting the optical properties. Surface treatment is preferred in terms of dispersibility with the binder (A). In particular, in the case of silica, acryloyl group-coated nanosilica is preferred because it can bond firmly with the acryloyl groups in (A).

[0029] The amount of the inorganic filler is preferably 30% by weight or less, more preferably 20% by weight or less, and particularly preferably 10% by weight or less, based on the total solid content. By using an amount of 30% by weight or less, sufficient elongation at break can be ensured. The average particle size is the median diameter (d=50) measured by a laser diffraction / scattering method in accordance with JIS Z 8825-1.

[0030] When applying the photocurable resin composition of the present invention (hereinafter referred to as the present resin composition) to a plastic substrate, it may be diluted with a solvent to improve coating properties. Examples of solvents that can be used 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 (hereinafter referred to as MEK), methyl isobutyl ketone (hereinafter referred to as MIBK), and cyclohexanone; ester-based solvents such as methyl acetate and butyl acetate; and ether-based solvents such as propylene glycol monomethyl ether (hereinafter referred to as PGM), diethyl ether, and diisopropyl ether. These solvents can be used alone or in combination of two or more. The solids content when diluted is typically 10 to 60%, but there are no particular restrictions and can be appropriately selected to achieve a viscosity that is easy to apply.

[0031] Examples of plastic substrates onto which the photoresist composition is applied include polyester films, triacetyl cellulose films, polycarbonate (hereinafter referred to as PC) films, polysulfone films, nylon films, cycloolefin films, acrylic films, polyimide films, ABS films, polyolefin films, PVC films, and PVA films. Among these, biaxially oriented polyester films are preferred in terms of weather resistance, processability, dimensional stability, and the like. Furthermore, PMMA films and PC films are preferred for automotive interior decoration, and laminated films thereof are also acceptable. The film thickness may be approximately 25 μm to 500 μm.

[0032] For the purpose of improving adhesion to the resin composition, the plastic substrate may be subjected to a surface treatment such as a primer treatment, a surface roughening treatment using a sandblasting method, a solvent treatment, or a surface oxidation treatment such as a corona discharge treatment, a chromic acid treatment, an ozone or ultraviolet irradiation treatment, etc. Conversely, for the purpose of improving releasability for use in transfer applications, a primer treatment using a release agent such as a silicone resin or a fluorine-based resin may be performed.

[0033] The method for applying the present resin composition is not particularly limited, and it can be formed by known coating methods such as spray coating, roll coating, die coating, air knife coating, blade coating, spin coating, reverse coating, gravure coating, wire bar coating, etc., or printing methods such as gravure printing, screen printing, offset printing, inkjet printing, etc. The thickness of the coated film when dry can be, for example, 1 μm to 10 μm, but is not limited to this.

[0034] The light source for UV irradiation used to cure the resin composition includes low-pressure mercury lamps, high-pressure mercury lamps, ultra-high-pressure mercury lamps, carbon arc lamps, xenon lamps, metal halide lamps, LED lamps, and electrodeless UV lamps. The irradiation atmosphere may be air or an inert gas such as nitrogen or argon. Furthermore, the curing property can be further improved by heating the coating film during UV irradiation using a back roll or an IR heater. The irradiation conditions are an irradiation intensity of 500 mW / cm. 2 ~3000mW / cm 2 , exposure dose 50-400mJ / cm 2 are exemplified, but are not limited to these.

[0035] The hard coat film obtained by applying the present resin composition to a plastic substrate and curing it preferably has a breaking elongation of 50% or more, more preferably 100% or more, and particularly preferably 150% or more, in an atmosphere of 130° C. By ensuring that the breaking elongation is 50% or more, it is expected that cracks will be prevented from occurring during molding, even in applications that require deep drawing.

[0036] The present invention will be described in detail below with reference to examples and comparative examples, but these are given as specific examples and are not intended to limit the scope of the present invention. Unless otherwise specified, measurements were carried out at a room temperature of 25°C and a relative humidity of 65%. The units in the recipe tables are parts by weight converted into solid content.

[0037] Preparation of urethane acrylate (hereinafter referred to as urea) 1 200 parts by weight of ethylene glycol (EG) and 786 parts by weight of IPDI (37.5% NCO group) were added to a catalyst in MEK solvent (50% solids) and stirred at 90°C for 120 minutes. The reaction was terminated when the isocyanate group peak reached a predetermined level by infrared absorption analysis. Next, 136 parts by weight of M-920 (product name: Toagosei Co., Ltd., hydroxyl value 240 mg KOH / g, biomass glycerin di / triacrylate) (a1) was added dropwise over 60 minutes at 70°C or below and stirred and reacted. The mixture was then stirred and reacted for 300 minutes at 80°C. Infrared absorption analysis confirmed the disappearance of the isocyanate groups. After cooling, the solids content was adjusted to 50% with MEK to obtain urea 1 (GDA-(IPDI-EG)n-IPDI-GDA) with a molecular weight of 4,000.

[0038] In addition to the above, Ureacs 2 to 7 having the following compositions were prepared. Urea 2: GDA-(IPDI-EG)n-IPDI-GDA, Mw 8,000 Urea 3: GDA-(IPDI-EG)n-IPDI-GDA, Mw 2,000 Ureac 4:PET3A-(IPDI-EG)n-IPDI-PET3A,Mw4,000 Urea 5: GDA-IPDI-PEG-IPDI-GDA, Mw 5,000 UREAC6: GDA-IPDI-GDA, UREAC7: GDA-HDI-GDA,

[0039] Example 1 Urea 1 as (A), Omnirad 2959 (trade name: manufactured by IGM Resins) as (B), and DPHA as a reactive diluent were mixed in the formulation shown in Table 1 until they were uniformly dissolved and dispersed, and PGM was further added thereto so that the solid content became 30%, followed by dilution and stirring to obtain a photocurable resin composition of Example 1.

[0040] Examples 2 to 10 In addition to the materials used in Example 1, Ureac 2 and 3 were used as (A), Suranimo D100 (trade name: manufactured by Osaka Gas Chemicals Co., Ltd., quaternary ammonium salt type) and Marukaside V-1 (trade name: manufactured by Osaka Kasei Co., Ltd., quaternary ammonium salt type) were used as (C), BYK-UV3500 (trade name: manufactured by BYK, silicone-based leveling agent) and KY-1203 (trade name: manufactured by Shin-Etsu Chemical Co., Ltd., fluorine silicone-based leveling agent) were used as surface conditioners, and ALMIBK30WT%-M47 (product name: manufactured by CIK Nanotech Co., Ltd., alumina particles, average particle size 30 nm, surface treated) and PGM-AC-2140Y (product name: manufactured by Nissan Chemical Industries, Ltd., average particle size 10 to 15 nm, acryloyl group surface treatment) were used as organic fillers, and the mixture was stirred until uniformly dissolved and dispersed in the formulation shown in Table 1. PGM was then added to the mixture so that the solid content was 30%, and the mixture was diluted and stirred to obtain the photocurable resin compositions of Examples 2 to 10.

[0041] Comparative Examples 1 to 4 In addition to the materials used in the examples, the above-mentioned Ureacs 4 to 7 were used as oligomers, and the mixture was stirred until uniformly dissolved and dispersed in the formulation shown in Table 1. PGM was then added to the mixture so that the solid content was 30%, and the mixture was diluted and stirred to obtain photocurable resin compositions for Comparative Examples 1 to 4.

[0042] Table 1 JPEG0007748836000001.jpg77135

[0043] The evaluation method was as follows.

[0044] Creating evaluation film The photocurable resin compositions prepared in the examples and comparative examples were coated onto DKW#200KK (trade name: manufactured by Keiwa Co., Ltd., a 200 μm thick biomass PC film made from Mitsubishi Chemical Corporation's Durabio) so that the dry film thickness was 3 μm. The film was then dried in a thermostatic chamber at 80°C for 1 minute, and then irradiated with ultraviolet light from a high-pressure mercury lamp at an output of 1300 mW / cm2 and an accumulated light amount of 200 mJ to prepare a film for evaluation.

[0045] Adhesion: According to the cross-cut method of JIS K 5600-5-6, a 10x10 grid was created with 1mm intervals on the coated surface, and cellophane tape CT-24 (product name: manufactured by Nichiban Co., Ltd.) was applied and pulled upward to check the peeling status. No peeling: 100 / 100 was rated as ◯, and peeling: 0 / 100 to 99 / 100 was rated as ×.

[0046] Breaking elongation: The hard-coated film was cut into a piece 25 mm wide x 50 mm long, and a tensile test was performed using a TechnoGraph TGI-1KN manufactured by Minebia at an ambient temperature of 130°C and a pulling speed of 300 mm / min. Cracks were checked visually, and an elongation rate of less than 50% was marked as ×, 50 to 100% as ○, and over 100% as ◎. Calculation formula: Calculate how many mm it has stretched based on 50 mm. (Stretched length (mm) / 50mm) x 100 = Stretch rate %

[0047] Fabric abrasion resistance: After a surface friction test using 100% cotton fabric (load 200 gf / cm², stroke width 50 mm, 10 round trips), the presence or absence of scratches was evaluated by visual inspection. No scratches were evaluated as ○, scratches were evaluated as ×, and ○ was evaluated as pass.

[0048] Chemical resistance: Hand cream Neutrogena SPF45 (trade name: Johnson & Johnson) was applied to the cured film and left at 80°C for 24 hours, then returned to room temperature and wiped off, after which the surface was observed. ○ indicates no trace of application, × indicates trace of application.

[0049] Antiviral activity value: Measured by the plaque assay method of ISO 21702:2019. Influenza A virus and feline calicivirus were used as test viruses, and the virus infectivity after 24 hours was measured. The difference in virus infectivity from the blank film was evaluated as the antiviral activity value, with a value of over 2.0 being evaluated as ◯ and a value of 2.0 or less being ×. This evaluation was performed only on Examples 3 and 4, which contained (C).

[0050] Evaluation results Table 2 JPEG0007748836000002.jpg48135

[0051] The Examples were satisfactory with no problems in terms of adhesion, elongation at break, fabric abrasion resistance, and chemical resistance, and Examples 3 and 4, which contained (C), showed good antiviral activity values.

[0052] On the other hand, Comparative Example 1, in which PET3A was used instead of (a1), had poor adhesion, Comparative Example 2, in which PEG was used instead of EO, had poor abrasion resistance and chemical resistance, and Comparative Examples 3 and 4, in which GDA was directly reacted with polyisocyanate, had low elongation at break, and none of these were suitable for the present invention.

Claims

1. A photocurable resin composition characterized by comprising: a urethane (meth)acrylate oligomer (A) obtained by further reacting a diisocyanate obtained by reacting only ethylene glycol and isophorone diisocyanate with a glycerin polyfunctional (meth)acrylate (a1); and a photopolymerization initiator (B).

2. 2. The photocurable resin composition according to claim 1, wherein the (a1) is a biomass (meth)acrylate using a plant-derived material.

3. 3. The photocurable resin composition according to claim 1, further comprising an antiviral agent (C).

4. A molding hard coat film comprising a plastic substrate and a cured layer of the photocurable resin composition according to any one of claims 1 to 3 on the plastic substrate.

5. 5. A hard coat film for molding, wherein the plastic substrate according to claim 4 is a biomass polycarbonate film.

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