Photocurable resin composition and laminate

Abstract

To provide a photocurable resin composition that can form a coat having both hardness and adhesiveness and also having high weather resistance and a laminate including the coat.SOLUTION: A photocurable resin composition contains (A) an oligomer with a weight average molecular weight (Mw) of 600-4000 and a double bond content of 0.8-6.5 meq / g, and (B) a dialkyl (meth)acrylate monomer having a bridged ring hydrocarbon group.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a photocurable resin composition and a laminate. [Background technology]

[0002] Coatings are formed on the surfaces of articles to decorate and protect them, and photocurable resin compositions that are cured by light such as ultraviolet light are widely used as materials for these coatings.

[0003] For example, Patent Document 1 describes an active energy ray-curable composition containing an active energy ray-polymerizable compound having an unsaturated double bond, an ultraviolet absorber, and a photopolymerization initiator. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2018-131481 Summary of the Invention [Problem to be solved by the invention]

[0005] Photocurable resin compositions are typically applied to substrate surfaces at a film thickness of 1 to 20 μm. While it is possible to apply the composition at a film thickness of 100 μm or more, this is rarely used in practical applications. This is because a film thickness of 100 μm or more makes it difficult to achieve a trade-off between film hardness and adhesion (low curl). Furthermore, when used outdoors, weather resistance is also required for the film. Films made from photocurable resin compositions may yellow when exposed to sunlight or other sources. Thin films make this yellowing less noticeable, while thick films make the color of the film more noticeable. For products requiring depth and transparency in surface designs, thick films are formed, but the above-mentioned issues make it difficult to use photocurable resin compositions. The baking process required increases costs and is environmentally harmful.

[0006] The photocurable resin composition of the present disclosure has been made in view of these problems, and one of its purposes is to provide a photocurable resin composition that can achieve both hardness and adhesion of the coating and can realize a coating with excellent weather resistance, and a laminate including the coating. [Means for solving the problem]

[0007] The photocurable resin composition of the present disclosure comprises: (A) an oligomer having a weight average molecular weight (Mw) of 600 to 4000 and a double bond concentration of 0.8 to 6.5 meq / g; (B) a di(meth)acrylic acid alkyl ester monomer having a bridged ring hydrocarbon group; and Includes:

[0008] The laminate of the present disclosure comprises: A substrate and a coating formed on a surface of the substrate, The coating is formed from the above-mentioned photocurable resin composition. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 4 is a schematic cross-sectional view illustrating a laminate according to a second embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0010] (First embodiment) The photocurable resin composition of the first embodiment includes (A) an oligomer having a weight-average molecular weight (Mw) of 600 to 4000 and a double bond concentration of 0.8 to 6.5 meq / g, and (B) a di(meth)acrylic acid alkyl ester monomer having a bridged ring hydrocarbon group. Hereinafter, component (B) is also referred to as a reactive diluent. By using a reactive diluent such as component (B), it is possible to achieve both hardness and adhesion even when the coating obtained from the photocurable resin composition is thick. Furthermore, a coating made using the photocurable resin composition of this embodiment exhibits little yellowing and excellent weather resistance, even when the coating is 100 μm or thicker.

[0011] The oligomer of component (A) has a weight-average molecular weight (Mw) of 600 to 4000 and a double bond concentration of 0.8 to 6.5 meq / g. Here, the weight-average molecular weight is a polystyrene-equivalent value measured by gel permeation chromatography. The double bond concentration of the oligomer of component (A) can be calculated from the theoretical weight-average molecular weight and the number of functional groups.

[0012] Examples of the oligomer of component (A) include urethane acrylate, polyester acrylate, acrylic acrylate, and epoxy acrylate. Among these, urethane acrylate, polyester acrylate, and acrylic acrylate are preferred from the viewpoints of curl resistance and weather resistance. The oligomer of component (A) may be a known oligomer or a commercially available oligomer.

[0013] Examples of the di(meth)acrylic acid alkyl ester monomer having a bridged ring hydrocarbon group of component (B) include tricyclodecane dimethanol di(meth)acrylate, isobornyl di(meth)acrylate, and adamantyl di(meth)acrylate. The monomer of component (B) may be a known monomer or a commercially available monomer.

[0014] From the viewpoint of achieving desirable hardness, adhesion, and weather resistance of the coating, the mass of component (B) per 100 parts by mass of component (A) is preferably 150 to 700 parts by mass.

[0015] The photocurable resin composition of this embodiment may further contain a polyalkylene glycol di(meth)acrylate monomer as component (C). Like component (B), component (C) is also referred to as a reactive diluent. Component (C) has the effect of reducing the inhibition of curing of the coating film by oxygen, and the inclusion of component (C) can improve curability. The polyalkylene glycol di(meth)acrylate monomer as component (C) may be a known compound or a commercially available compound. From the viewpoint of curling resistance, the polyalkylene glycol di(meth)acrylate monomer as component (C) is preferably polyethylene glycol diacrylate represented by the following formula (1): [ka] In the formula, n is an integer between 6 and 12. be .

[0016] From the viewpoint of further improving the hardness, adhesion, and weather resistance of the coating, it is preferable that the mass of component (B) is 150 to 450 parts by mass per 100 parts by mass of component (A), and the mass of component (C) is 5 to 80 parts by mass per 100 parts by mass of component (B). More preferably, the mass of component (C) is 5 to 60 parts by mass per 100 parts by mass of component (B), and particularly preferably, the mass of component (C) is 5 to 40 parts by mass per 100 parts by mass of component (B).

[0017] The photocurable resin composition of this embodiment may further contain a photopolymerization initiator (D), a component. The photopolymerization initiator (D) is preferably a photoradical polymerization initiator, and from the viewpoint of further improving the weather resistance of the coating, an intramolecular hydrogen abstraction type photoradical polymerization initiator is more preferably used. Examples of intramolecular hydrogen abstraction type photoradical polymerization initiators include Omnirad 754 (manufactured by IGM Resins) and Omnirad MBF (manufactured by IGM Resins). From the viewpoints of weather resistance and curability, the mass of the photopolymerization initiator (D) is preferably 1 to 10 parts by mass, more preferably 3 to 7 parts by mass, per 100 parts by mass of the oligomer (A) and the reactive diluent (B) combined.

[0018] When the composition contains the (C) component, the mass of the photopolymerization initiator (D) is preferably 1 to 10 parts by mass, and more preferably 3 to 7 parts by mass, per 100 parts by mass of the oligomer (A), the reactive diluent (B), and the polyalkylene glycol di(meth)acrylate monomer (C) combined.

[0019] The photocurable resin composition of this embodiment may contain various additives in addition to the above-described components (A), (B), (C), and (D), depending on the intended use. Examples of such additives include surface conditioners, oxygen inhibitors, fillers, plasticizers, light stabilizers, antioxidants, and ultraviolet inhibitors. The photocurable resin composition of this embodiment can be cured in an oxygen-containing air atmosphere without the addition of an oxygen inhibitor or with the addition of only a small amount of an oxygen inhibitor.

[0020] The oxygen inhibition inhibitor may be, for example, an amine-based or thiol-based one. When an amine-based or thiol-based oxygen inhibition inhibitor is used, it is preferably contained in an amount of 10 parts by mass or less per 100 parts by mass of the total of components (A), (B), and (C), from the viewpoint of weather resistance.

[0021] The photocurable resin composition of this embodiment may be either a solvent-based resin composition diluted with an organic solvent such as thinner, or a solventless resin composition that is not diluted with an organic solvent. Solventless resin compositions are preferred because they leave no residual volatile organic compounds (VOCs), have minimal impact on the human body, and are environmentally friendly. The viscosity of the solventless resin composition can be adjusted to an appropriate level without adding an organic solvent by controlling the content of the reactive diluent component (B) or the content of components (B) and (C).

[0022] (Second embodiment) As shown in FIG. 1, a laminate 10 of the second embodiment includes a substrate 12 and a coating 14 formed on the surface of the substrate.

[0023] The type of material that constitutes the substrate 12 is not particularly limited, and examples thereof include plastic, metal, inorganic material other than metal, paper, wood, leather, and the like.

[0024] The coating 14 is formed from the photocurable resin composition of the first embodiment described above. The coating 14 has desirable hardness and adhesion and excellent weather resistance over a wide range of thicknesses (for example, 20 to 200 μm). The thickness of the coating 14 can be appropriately set depending on the type of substrate and the purpose of the laminate, etc. Even when the thickness of the coating 14 is relatively large, at 100 to 200 μm, the hardness, adhesion, and weather resistance can be maintained or improved without deterioration.

[0025] The coating 14 can be formed on the substrate 12 by applying a photocurable resin composition to the substrate 12 and curing it. Methods for applying the photocurable resin composition to the substrate 12 include, for example, hand coating, spray coating, a dip coater, a roll coater, a spin coater, a flow coater, electrostatic coating, and inkjet coating. The applied photocurable resin composition can be cured by irradiating it with ultraviolet light. The ultraviolet light irradiation required for curing can be performed by appropriately adopting known methods and curing conditions.

[0026] A top coat layer may be further formed on the surface of the coating 14. This allows various functions to be imparted to the surface of the laminate 10 while maintaining the design of the laminate 10. In particular, when an ultraviolet-curable top coat layer is used as the top coat layer, both the top coat layer and the coating 12 can be cured by a single photo-curing step, making it possible to produce the laminate 10 at low cost.

[0027] The laminate 10 can be suitably used in a wide range of applications due to the wide range of thicknesses of the coating 14. Examples of applications of the laminate 10 include decorative panels, flooring, and sashes. Furthermore, when manufacturing the laminate 10, the coating is light-cured without the need for baking, which reduces costs and the burden on the environment, and allows for the expression of designs with depth and transparency on the surface of even a substrate 12 that is sensitive to heat.

[0028] The present invention will be described in more detail below with reference to examples, but these examples are not intended to limit the present invention in any way. [Example]

[0029] Photocurable resin compositions of each example and comparative example were prepared according to the formulations shown in Tables 1 and 2 below. The photocurable resin compositions of each example and comparative example were solventless resin compositions that were not diluted with an organic solvent. The values ​​in the tables indicate parts by mass. [Table 1] [Table 2] *1 Tricyclodecane dimethanol diacrylate: Product name: A-DCP, manufactured by Shin-Nakamura Chemical Co., Ltd. *2 Polyethylene glycol diacrylate (Mn = 400) where n = 9 in the above general formula (1): Product name: NK Ester A-400, manufactured by Shin-Nakamura Chemical Co., Ltd. *3 1,6-Hexanediol diacrylate (HDDA): Product name: Viscoat #230, manufactured by Osaka Organic Chemical Industry Co., Ltd. *4 Intramolecular hydrogen abstraction type photoradical polymerization initiator: Product name: Omnirad754, manufactured by IGM Resins. *5 Amine-modified polyether acrylate: Product name: EBECRYL80, manufactured by Daicel Allnex Co., Ltd.

[0030] Details of the oligomers (A-1) to (A-7) in Tables 1 and 2 are shown in Table 3 below. [Table 3]

[0031] The method for preparing the photocurable resin composition will be described below. Example 1 100 parts by mass of oligomer (A-1) and 450 parts by mass of monomer B were weighed into a glass beaker and mixed and stirred for 5 minutes with a stirrer. To the homogenized mixture, 38.5 parts by mass of a polymerization initiator (7 parts by mass relative to the total of 100 parts by mass of oligomer (A-1) and monomer B) was added, and the mixture was mixed and stirred for 5 minutes with a stirrer to obtain a photocurable resin composition (Example 1).

[0032] Example 2 100 parts by mass of oligomer (A-1), 190 parts by mass of monomer B, and 10 parts by mass of monomer C were weighed into a glass beaker and mixed and stirred for 5 minutes with a stirrer. To the homogenized mixture, 21 parts by mass of a polymerization initiator (7 parts by mass relative to the total of 100 parts by mass of oligomer (A-1), monomer B, and monomer C) was added, and the mixture was mixed and stirred for 5 minutes with a stirrer to obtain a photocurable resin composition (Example 2).

[0033] Examples 3 to 8 Photocurable resin compositions (Examples 3 to 8) were obtained in the same manner as in Example 2, except that the content of each component was changed as shown in Table 1.

[0034] Example 9 100 parts by mass of oligomer (A-1), 300 parts by mass of monomer B, 100 parts by mass of monomer C, and 50 parts by mass of oxygen inhibition suppressor (10 parts by mass relative to 100 parts by mass of oligomer (A-1), monomer B, and monomer C combined) were weighed into a glass beaker and mixed and stirred for 5 minutes with a stirrer. To the homogenized mixture, 35 parts by mass of polymerization initiator (7 parts by mass relative to 100 parts by mass of oligomer (A-1), monomer B, and monomer C combined) was added, and the mixture was mixed and stirred for 5 minutes with a stirrer to obtain a photocurable resin composition (Example 9).

[0035] (Comparative Example 1) 100 parts by mass of oligomer (A-1) and 150 parts by mass of monomer C were weighed into a glass beaker and mixed and stirred for 5 minutes with a stirrer. To the homogenized mixture, 17.5 parts by mass of a polymerization initiator (7 parts by mass relative to the total of 100 parts by mass of oligomer (A-1) and monomer C) was added, and the mixture was mixed and stirred for 5 minutes with a stirrer to obtain a photocurable resin composition (Comparative Example 1).

[0036] (Comparative Example 2) 100 parts by mass of oligomer (A-1), 150 parts by mass of monomer C, and 300 parts by mass of HDDA were weighed into a glass beaker and mixed and stirred for 5 minutes with a stirrer. To the homogenized mixture, 38.5 parts by mass of a polymerization initiator (7 parts by mass relative to the total of 100 parts by mass of oligomer (A-1), monomer C, and HDDA) was added, and the mixture was mixed and stirred for 5 minutes with a stirrer to obtain a photocurable resin composition (Comparative Example 2).

[0037] (Examples 10 to 13 and Comparative Examples 3 and 4) Photocurable resin compositions (Examples 10 to 13 and Comparative Examples 3 and 4) were obtained in the same manner as in Example 5, except that the component (A) was changed to A-2 to A-7 in Table 2.

[0038] Example 14 A photocurable resin composition (Example 14) was obtained in the same manner as in Example 2, except that 1,3-adamantanediol diacrylate (manufactured by Daken Chemical Co.) was used as the component (B).

[0039] Example 15 A photocurable resin composition (Example 15) was obtained in the same manner as in Example 2, except that polyethylene glycol diacrylate (Mn=600) (trade name: NK Ester A-600, manufactured by Shin-Nakamura Chemical Co., Ltd.), in which n=14 in the above general formula (1), was used as component (C).

[0040] The photocurable resin compositions of each Example and Comparative Example were applied to a methacrylic resin substrate (Acrylite, 2 mm thick, white, manufactured by Mitsubishi Chemical Corporation) using an applicator to a thickness of 100 μm. Then, in the presence of air, an ultraviolet irradiation device (equipped with a metal halide lamp, manufactured by Eye Graphics Co., Ltd.) was used to apply the composition to a substrate with an integrated light intensity of 1000 mJ / cm at a wavelength of 365 nm. 2 The coating was then irradiated with ultraviolet light at 1000 kJ / min and photocured. In all of the examples and comparative examples, a cured coating was obtained. The hardness and weather resistance of the resulting coating were evaluated according to the following methods.

[0041] (scratch hardness) The hardness of the coating was evaluated by scratch hardness (pencil method). The scratch hardness of the coating was measured under a load of 750±10 g in accordance with JIS K5600-5-4. The measured scratch hardness was evaluated according to the following criteria. The evaluation results are shown in Table 5. Excellent: Scratch hardness is HB or higher Good: Scratch hardness is 2B or higher but lower than HB Poor: Scratch hardness is less than 2B

[0042] (color difference) The weather resistance of the coating was evaluated by color difference. Using a sunshine carbon arc lamp weather resistance tester specified in JIS B 7753, light irradiation was performed under the conditions specified in Table 4 below (old JIS K 5400). The irradiation time was 200 hours. In accordance with JIS K 5600-4-6, color coordinates were measured before and after irradiation using a CR-400 color difference meter (manufactured by Konica Minolta Japan, Inc.) to determine the color difference ΔE. The color difference ΔE was evaluated according to the following criteria. The evaluation results are shown in Table 5. Excellent: ΔE≦3.0 Good: 3.0<ΔE≦5.0 Defective: 5.0<ΔE [Table 4]

[0043] Furthermore, the adhesion of the coatings of the examples and comparative examples was evaluated according to the following method.

[0044] (Curling) The adhesion of the coating was evaluated by curling. The photocurable resin composition of each example and comparative example was applied to a hiding power measurement paper (manufactured by TP Giken Co., Ltd.) using an applicator to a film thickness of about 100 μm, and then exposed to a metal halide lamp with a wavelength of 365 nm and an integrated light intensity of 1000 mJ / cm. 2 The cured coating was irradiated with ultraviolet light at 100°C and photocured. A 7cm x 7cm test piece was cut from the cured coating and left to stand in an incubator set at 35°C for 1 hour, then removed and left to stand at room temperature for at least 1 hour. The test piece was then placed with the coating facing up on a flat surface, and the height of the raised corners (the height from the flat surface to the test piece) was measured at each of the four corners, and the arithmetic mean of the measured values ​​at the four corners was calculated. A smaller mean value indicates less deformation and better adhesion. The mean values ​​were evaluated according to the following criteria. The evaluation results are shown in Table 5. Excellent: average value 14mm or less Good: Average value is greater than 14 mm and less than 16 mm Poor: average value greater than 16 mm

[0045] [Table 5]

[0046] The evaluation results of each example and comparative example are explained below. When one or more of hardness, adhesion, and weather resistance are poor, it means that the product is difficult to use or has deteriorated properties compared to conventional products (comparative examples), and when all of hardness, adhesion, and weather resistance are good or better, it means that the product is usable and has improved properties (examples).

[0047] Examples 1 to 9 The composition of Example 1, which contained components (A) and (B) but did not contain component (C), had excellent hardness, good adhesion, and excellent weather resistance, and each evaluation was good or better. Examples 2 to 5, which contained components (A), (B), and (C) and in which the mass of component (C) was 5, 18, and 33 parts by mass per 100 parts by mass of component (B), respectively, were excellent in hardness, adhesion, and weather resistance. Examples 6 and 7, which contained components (A), (B), and (C) and in which the mass of component (C) was 54 parts by mass per 100 parts by mass of component (B), were inferior to Examples 2 to 5, but had good hardness, excellent adhesion, and excellent weather resistance, and each evaluation was good or better. Example 8, which contains components (A), (B), and (C), in which the mass of component (C) is 75 parts by mass per 100 parts by mass of component (B), is inferior to Examples 1 to 7, but has good hardness, excellent adhesion, and good weather resistance, and each evaluation was good or better. Example 9, in which an oxygen inhibition inhibitor was further added to Example 5, is inferior to Example 5, but has good hardness, excellent adhesion, and good weather resistance, and each evaluation was good or better.

[0048] Comparison Examples 1 and 2 Comparative Example 1, which contained components (A) and (C) but not component (B), had excellent adhesion but poor hardness and poor weather resistance. Comparative Example 2, which contained components (A) and (C), not component (B), and further contained HDDA, had good adhesion and good weather resistance but poor hardness.

[0049] Examples 10 to 13 In Examples 10 to 13, which used oligomers (A-2) to (A-5) having a weight-average molecular weight (Mw) of 600 to 4000 and a double bond concentration of 0.8 to 6.5 meq / g as component (A), the hardness was excellent in all cases, the weather resistance was excellent in all cases, and the adhesion was excellent in Examples 12 and good in Examples 10, 11, and 13, with each evaluation being good or better.

[0050] Comparative Examples 3 and 4 Comparative Example 3, in which an oligomer (A-6) having a weight-average molecular weight (Mw) of 5000 (>4000) and a double bond concentration of 0.4 meq / g (<0.8 meq / g) was used as component (A), exhibited excellent adhesion and weather resistance, but poor hardness. Comparative Example 4, in which an oligomer (A-7) having a double bond concentration of 7.5 meq / g (>6.5 meq / g) was used as component (A), exhibited excellent hardness and weather resistance, but poor adhesion.

[0051] Examples 14 and 15 Example 14, in which the tricyclodecane dimethanol diacrylate of Example 2 was changed to 1,3-adamantanediol diacrylate as the component (B), was excellent in all of the hardness, adhesion, and weather resistance, similar to Example 2. Example 15, in which the polyethylene glycol diacrylate (in general formula (1), n ​​= 9, Mn = 400) of Example 2 was changed to polyethylene glycol diacrylate (in general formula (1), n ​​= 14, Mn = 600) as the component (C), was excellent in all of the hardness, adhesion, and weather resistance, similar to Example 2.

[0052] The configuration of the present disclosure is not limited to the above-described embodiments, and many modifications and variations are possible. For example, each component can be changed or replaced as long as there is no logical contradiction. Hatching in the cross-sectional view does not limit the material of the hatched object. [Explanation of symbols]

[0053] 10 Laminate 12 Base material 14 Coating

Claims

1. (A) an oligomer having a weight average molecular weight (Mw) of 600 to 4000 and a double bond concentration of 0.8 to 6.5 meq / g; (B) a di(meth)acrylic acid alkyl ester monomer having a bridged ring hydrocarbon group; (C) polyethylene glycol diacrylate represented by the following formula (1), The mass of the (B) component per 100 parts by mass of the (A) component is 150 to 450 parts by mass, A photocurable resin composition characterized in that the mass of component (C) is 5 to 80 parts by mass per 100 parts by mass of component (B). 【Chemistry 1】 (wherein n is an integer from 6 to 12.)

2. 2. The photocurable resin composition according to claim 1, further comprising an amine-based or thiol-based oxygen inhibition suppressor in an amount of 10 parts by mass or less per 100 parts by mass of the total of the components (A), (B), and (C).

3. A substrate and a coating formed on a surface of the substrate, 3. A laminate, wherein the coating is formed from the photocurable resin composition according to claim 1.

4. 4. The laminate according to claim 3, wherein the thickness of the coating is 100 to 200 μm.

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