Laminated sheet

Abstract

To provide a laminated sheet exhibiting superior hardness as well as high glossiness.SOLUTION: A laminated sheet 1 comprises a substrate 2 and a surface layer 3 provided on a surface of the substrate 2, the surface layer 3 containing a urethane acrylate having a functionality of three or less, an acrylate having a functionality of three or more, and zinc acrylate. The content of zinc acrylate relative to the total content of the urethane acrylate having a functionality of three or less, the acrylate having a functionality of three or more, and the zinc acrylate in the surface layer 3 is 5 mass% or more and 95 mass% or less.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a laminated sheet. [Background technology]

[0002] Laminated sheets are used to enhance gloss and scratch resistance in a variety of applications, including wall materials, fixtures, building materials such as fittings, surface decoration for furniture, and decorative sheets for mobility-related applications and window materials for mobility.

[0003] As this laminated sheet, there is known one in which a hard coat layer is provided on the surface of the substrate to prevent scratches.

[0004] For example, a decorative sheet has been proposed that includes a substrate and a curable resin layer containing an uncured or semi-cured curable component provided on one side of the substrate, the substrate being composed of an amorphous resin having a glass transition temperature of 90° C. or higher. It is also described that a decorative sheet can be provided that includes a hard coat layer formed from an uncured or semi-cured curable component, and that has a pencil hardness of H or higher (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-121178 Summary of the Invention [Problem to be solved by the invention]

[0006] Here, the decorative sheet described in Patent Document 1 above has a hard coat layer, but the coated decorative sheet has an uncured or semi-cured curable resin layer that requires post-curing, so there is a problem in that sufficient hardness cannot be obtained unless post-curing is performed, in which the uncured or semi-cured curable component is three-dimensionally processed and then cured.

[0007] The present invention has been made in view of the above problems, and has as its object to provide a laminate sheet that has excellent hardness and high gloss even without post-curing. [Means for solving the problem]

[0008] In order to achieve the above object, the laminate sheet of the present invention comprises a substrate and a surface layer provided on the surface of the substrate and containing a urethane acrylate having a functionality of 3 or less, an acrylate having a functionality of 3 or more, and zinc acrylate, and is characterized in that the content of zinc acrylate in the surface layer relative to the total content of the urethane acrylate having a functionality of 3 or less, the content of the acrylate having a functionality of 3 or more, and the content of the zinc acrylate is 5% by mass or more and 95% by mass or less. [Effects of the Invention]

[0009] According to the present invention, it is possible to provide a laminate sheet that is excellent in hardness and has high gloss. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a cross-sectional view showing a laminate sheet according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0011] The laminate sheet of the present invention will be specifically described below. Note that the present invention is not limited to the following embodiments, and can be appropriately modified and applied within the scope of the present invention.

[0012] <Laminated sheet> As shown in FIG. 1, the laminate sheet 1 of the present invention includes a substrate 2 and a surface layer 3 provided on a surface 2 a of the substrate 2 .

[0013] <Base material> The substrate 2 is made of, for example, a thermoplastic resin sheet, and as this thermoplastic resin sheet, any of those typically used for the substrate in the laminate sheet 1 can be used. Specific examples include polyvinyl chloride (PVC) sheets, glycol-modified polyethylene terephthalate (PETG) sheets, amorphous crystalline polyester resin (APET) sheets, polyolefin sheets (polyethylene sheets, polypropylene sheets, etc.), acrylonitrile-butadiene-styrene resin (ABS) sheets, polycarbonate sheets, acrylic resin (PMMA) sheets, etc. Furthermore, examples of amorphous crystalline polyester resin (APET) sheets used for the substrate 2 include recycled polyethylene terephthalate (RPET) sheets made from PET bottles and the like.

[0014] The thermoplastic resin sheet is preferably a resin that can be easily processed into a quadratic curved surface and has excellent three-dimensional formability.

[0015] The thermoplastic resin sheet may be a stretched sheet or an unstretched sheet, and may contain additives such as colorants, ultraviolet absorbers, light stabilizers, antioxidants, antistatic agents, storage stabilizers, lubricants, and fillers, as needed.

[0016] The thickness of the substrate 2 is not particularly limited, but is preferably 0.05 mm to 30 mm, and more preferably 0.25 to 10 mm. If the thickness of the substrate 2 is 0.05 mm or more, the mechanical strength and hiding power can be sufficiently improved. Furthermore, if the thickness of the substrate 2 is 30 mm or less, the substrate can be produced continuously by extrusion molding.

[0017] <Surface layer> The surface layer 3 is a coating film of a paint whose main component is urethane acrylate. This surface layer 3 can be formed by applying the paint to the surface 2a of the substrate 2 and curing it, and the surface layer 3 is formed from the cured paint.

[0018] The urethane acrylate used may be a trifunctional or lower functional urethane acrylate, such as an aliphatic urethane acrylate or an aromatic urethane acrylate. Commercially available products such as UV-6640B, UV-7000B, UV-3000B, UV-6630B, EBECRYL8465, EBECRYL4740, EBECRYL270, EBECRYL9260, EBECRYL8402, EBECRYL8701, EBECRYL8409, EBECRYL8804, KRM7735, and EBECRYL8809 (all trade names) can also be used. These urethane acrylates may be used alone or in combination of two or more.

[0019] Furthermore, the weight average molecular weight (Mw) of the tri- or lower functional urethane acrylate of the present invention is at least 1000. If the weight average molecular weight is at least 1000, the flexibility of the coating film is improved, making three-dimensional molding possible.

[0020] The term "weight average molecular weight" used herein refers to the weight average molecular weight calculated in terms of polystyrene obtained by gel permeation chromatography (GPC) measurement.

[0021] Furthermore, the surface layer 3 contains a tri- or higher functional acrylate as the polyfunctional (meth)acrylate. The use of this tri- or higher functional acrylate makes it possible to improve the hardness of the coating film.

[0022] The term "polyfunctional (meth)acrylate" used herein refers to a (meth)acrylic acid ester monomer containing two or more (meth)acryloyl groups.

[0023] Examples of tri- or higher functional acrylates include trimethylolpropane triacrylate, trimethylolpropane ethoxy triacrylate, glycerin propoxy triacrylate, pentaerythritol (tri / tetra)acrylate, pentaerythritol alkoxytetraacrylate, pentaerythritol ethoxytetraacrylate, ditrimethylolpropane tetraacrylate, and dipentaerythritol hexaacrylate. Commercially available products such as TMPTA, DPHA, PETA, PETIA, PETRA, EBECRYL895, EBECRYL160S, EBECRYL40, EBECRYL50, EBECRYL140, EBECRYL1140, EBECRYL896, and EBECRYL1142 (all trade names) can also be used. These tri- or higher functional acrylates may be used alone or in combination of two or more.

[0024] Furthermore, from the viewpoint of imparting hardness to the surface layer 3 and improving the hardness of the coating film, the weight average molecular weight (Mw) of the tri- or higher functional acrylate of the present invention is preferably less than 1,000.

[0025] The blending ratio of the tri- or lower functional urethane acrylate to the tri- or higher functional acrylate in the surface layer 3 is not particularly limited as long as it does not impair the characteristics of the laminate sheet 1 of the present invention, but the mass ratio of the tri- or lower functional urethane acrylate to the tri- or higher functional acrylate is preferably in the range of 3:1 to 200:1. This is because a high mass ratio of the tri- or lower functional urethane acrylate may result in a coating film with poor hardness, and a high mass ratio of the tri- or higher functional acrylate may result in a coating film with poor three-dimensional formability.

[0026] Here, the present inventors have found that by incorporating zinc acrylate into the surface layer 3 of the laminate sheet 1, the hardness of the laminate sheet 1 can be improved.

[0027] More specifically, by using zinc acrylate, the zinc acrylate acts as a crosslinking agent for the resin components (the above-mentioned trifunctional or lower urethane acrylates and trifunctional or higher acrylates), improving the crosslink density of the resin components and making the coating film stronger, which ultimately makes it possible to improve the hardness of the surface layer 3.

[0028] Furthermore, the content of zinc acrylate relative to the total of the tri- or less functional urethane acrylate content, the tri- or more functional acrylate content, and the zinc acrylate content in the surface layer 3 (i.e., the content of zinc acrylate [% by mass] when the total of the tri- or less functional urethane acrylate content, the tri- or more functional acrylate content, and the zinc acrylate content in the surface layer is taken as 100% by mass; hereinafter, referred to as the "content of zinc acrylate in the surface layer") is 5% by mass or more and 95% by mass or less. This is because if the content of zinc acrylate in the surface layer is less than 5% by mass, the hardness may not be sufficiently improved, and if the content of zinc acrylate in the surface layer is more than 95% by mass, although the hardness is improved, the coating film may become too brittle, resulting in cracks on the surface.

[0029] That is, in the present invention, the surface layer 3 contains a urethane acrylate with three or fewer functionalities, an acrylate with three or more functionalities, and zinc acrylate, and the content of zinc acrylate in the surface layer 3 is 5% by mass or more and 95% by mass or less, thereby making it possible to improve the hardness of the laminate sheet 1.

[0030] Furthermore, the thickness of the surface layer 3 is not particularly limited, but is preferably 0.01 to 30 μm, because if the thickness of the surface layer 3 is greater than 30 μm, cracks may occur during secondary molding.

[0031] Furthermore, the coating material may contain other components in addition to the tri- or lower functional urethane acrylate, the tri- or higher functional acrylate, and the zinc acrylate, as long as the effects of the invention are not impaired. Examples of such other components include photopolymerization initiators, colorants, UV absorbers, light stabilizers, antioxidants, antistatic agents, storage stabilizers, plasticizers, lubricants, and fillers.

[0032] As the photopolymerization initiator, for example, an alkylphenone-based initiator, an acylphosphine oxide-based initiator, a cationic initiator, or the like can be used.

[0033] <Manufacturing method> When producing the laminate sheet 1 of the present invention, first, a substrate 2 made of, for example, the above-mentioned thermoplastic resin sheet is prepared. This thermoplastic resin sheet may be a commercially available one, or may be produced by a known production method such as a calendar method or an extrusion molding method.

[0034] Next, a coating material containing, for example, the above-mentioned trifunctional or lower urethane acrylate, trifunctional or higher acrylate, zinc acrylate, and a photopolymerization initiator added to a solvent such as methyl ethyl ketone is applied to the surface 2a of the substrate 2, to form a coating film that will become the surface layer 3 on the surface 2a of the substrate 2.

[0035] The coating method is not particularly limited, and examples thereof include cast coating, die coating, gravure coating, roll knife coating, reverse roll coating, roll coating, comma coating, dip coating, and flow coating.

[0036] Then, the coating is cured by irradiating it with ultraviolet light (350 to 450 nm), thereby producing a laminate sheet 1 having a surface layer 3 formed on the surface 2a of the substrate 2 as shown in FIG.

[0037] Furthermore, in the laminate sheet 1 of the present invention, the glossiness of the surface 3a of the surface layer 3 (that is, the surface opposite to the substrate 2 side) is 50 or more, so that high glossiness can be achieved.

[0038] From the viewpoint of improving high gloss, the gloss of the surface 3a of the surface layer 3 is preferably 50 or more, and more preferably 80 or more.

[0039] Furthermore, the term "glossiness" as used herein refers to the 60° glossiness measured in accordance with JIS Z 8741:1997, which is calculated based on the results of measurement using a photodetector installed in the direction of the reflection angle when light is incident at an incident angle of 60° on the measurement surface (surface 3a of the surface layer 3) of the laminated sheet 1.

[0040] Furthermore, in the laminate sheet 1 of the present invention, as described above, the use of zinc acrylate can improve the hardness of the surface layer 3, making it possible to obtain a good pencil hardness. From the viewpoint of use as a decorative sheet for the mobility-related decorative sheet described above in addition to decorative sheets that are building materials, the pencil hardness of the surface layer 3 is preferably HB or higher, and more preferably F or higher.

[0041] The "pencil hardness" referred to here refers to the pencil hardness (750 g load) measured in accordance with JIS K5600-5-4 (1999).

[0042] As described above, the present invention makes it possible to provide a laminate sheet that is excellent in hardness and has high gloss. [Example]

[0043] The present invention will be described below based on examples. However, the present invention is not limited to these examples, and these examples can be modified or changed based on the spirit of the present invention, and such modifications are not excluded from the scope of the present invention.

[0044] The materials used to prepare the laminated sheet are listed below. (1) Urethane acrylate - 1: Difunctional urethane acrylate (weight average molecular weight: 5000, manufactured by Mitsubishi Chemical Corporation, trade name: UV-6640B) (2) Urethane acrylate-2: Difunctional urethane acrylate (weight average molecular weight: 3500, manufactured by Mitsubishi Chemical Corporation, product name: UV-7000B) (3) Urethane acrylate-3: Trifunctional urethane acrylate (weight average molecular weight: 1400, manufactured by Daicel Allnex Co., Ltd., trade name: EBECRYL8465) (4) Multifunctional (meth)acrylate - 1:3 functional acrylate (acrylic equivalent: 95, weight average molecular weight: 286, manufactured by Daicel Allnex Co., Ltd., trade name: trimethylolpropane triacrylate (TMPTA)) (5) Multifunctional (meth)acrylate - 2:6 functional acrylate (acrylic equivalent: 87), weight average molecular weight: 520, manufactured by Daicel Allnex Co., Ltd., trade name: dipentaerythritol hexaacrylate (DPHA) (6) Zinc acrylate (zinc content: 10.6% by mass, manufactured by Asada Chemical Industry Co., Ltd., product name: ZN-AP-M2) (7) Initiator: alkylphenone-based photopolymerization initiator (manufactured by IGM Resins BV, trade name: Omnirad1173)

[0045] Example 1 <Production of laminated sheets> First, a PVC substrate having a thickness of 250 μm was prepared. Next, the materials shown in Table 1 were blended to prepare a coating material of Example 1 having the composition (parts by mass) shown in Table 1. This coating material was applied to the surface of the substrate using a bar coater to form a coating film that would become a surface layer on the surface of the substrate.

[0046] Next, the coating film was irradiated with ultraviolet light (dominant wavelength: 365 nm) using an ultraviolet irradiation device (4 kW ultraviolet curing high-pressure mercury lamp (H04-L41) manufactured by Eye Graphics Co., Ltd.) to photo-cure the coating film, thereby forming a surface layer on the surface of the substrate and producing a laminated sheet. The ultraviolet light irradiation was performed under conditions of an irradiation distance of 15 cm, a lamp movement speed of 0.50 m / min, and an irradiation dose of 250 mJ / cm. 2 It was decided.

[0047] <Thickness measurement> Next, the thickness of the surface layer (coating film) of the prepared laminated sheet was measured using a digital microscope (Keyence Corporation, product name: VHX-5000) or a field emission scanning electron microscope (SEM) (Hitachi High-Technologies Corporation, product name: S-4800).

[0048] More specifically, the sheet was cut to expose the cross section, and the thickness [μm] was measured when the cross section was observed using a digital microscope (measurement magnification: 500x) or a field emission scanning electron microscope (measurement magnification: 1000x), and the average value was calculated. The above measurement was performed three times, and the average value of the coating film heights for the three measurements was calculated and used as the thickness of the surface layer. The results are shown in Table 1.

[0049] <Gloss measurement> The 60° gloss of the surface layer of the prepared laminate sheet was measured in accordance with JIS Z 8741:1997 using a gloss meter (manufactured by Horiba, Ltd., product name: Gloss Checker IG-320). The measurement was performed three times, and the average value of the three gloss values ​​was calculated and used as the gloss of the surface layer. The results are shown in Table 1.

[0050] <Pencil hardness measurement> In accordance with JIS K5600-5-4 (1999), the pencil hardness of the surface layer of the prepared laminate sheet was measured using a pencil hardness tester (manufactured by Shinto Scientific Co., Ltd., product name: HEIDON-14DR) under conditions of a load of 750 g, a speed of 1 mm / sec, and a pencil (manufactured by Mitsubishi Pencil Co., Ltd., product name: uni) angled at 45° to the laminate sheet. The pencil hardness was determined as the hardest pencil hardness that did not cause scratches on the surface of the surface layer when scratched with pencils of each hardness. The results are shown in Table 1.

[0051] <Evaluation of paint appearance> The surface of the coating film (coating film that becomes the surface layer) applied to the surface of the substrate was visually observed, and the coating appearance was evaluated based on the following criteria. The results are shown in Table 1.

[0052] The painted surface is smooth, crack-free, and glossy: ○ Cracks on the painted surface: ×

[0053] (Examples 2 to 8, Comparative Examples 1 and 2) A laminate sheet was produced in the same manner as in Example 1 above, except that the composition of the coating components was changed to the composition (parts by mass) shown in Table 1.

[0054] Then, the thickness, gloss, and pencil hardness were measured, and the coating appearance was evaluated in the same manner as in Example 1. The results are shown in Tables 1 and 2.

[0055] [Table 1]

[0056] [Table 2]

[0057] As shown in Table 1, the laminate sheets of Examples 1 to 8, in which the surface layer contains a urethane acrylate with three or fewer functionalities, an acrylate with three or more functionalities, and zinc acrylate, and the content of zinc acrylate in the surface layer is 5% by mass or more and 95% by mass or less, have a glossiness of 50 or more in the surface layer, and therefore have high gloss. Furthermore, the laminate sheets of Examples 1 to 8 have a pencil hardness of HB or more, and therefore have excellent hardness. [Industrial Applicability]

[0058] As described above, the present invention is suitable for laminated sheets. [Explanation of symbols]

[0059] 1. Laminated sheet 2 Base material 2a Surface of the substrate 3 Surface layer 3a Surface of the surface layer

Claims

1. A substrate; a surface layer provided on the surface of the substrate, the surface layer containing a tri- or less functional urethane acrylate, a tri- or more functional acrylate, and zinc acrylate; Equipped with A laminated sheet characterized in that the content of the zinc acrylate in the surface layer relative to the total content of the urethane acrylate having a functionality of three or less, the content of the acrylate having a functionality of three or more, and the content of the zinc acrylate is 5% by mass or more and 95% by mass or less.

2. 2. The laminate sheet according to claim 1, wherein the surface layer has a pencil hardness (750 g load) of HB or more as measured in accordance with JIS K5600-5-4 (1999).

3. 3. The laminate sheet according to claim 1, wherein the surface layer has a glossiness of 50 or more.

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