Light-transmitting decorative sheet, method for manufacturing a light-transmitting decorative sheet, decorative molded product, and method for manufacturing a decorative molded product

Abstract

The objective is to provide a light-transmitting decorative sheet with good moldability during injection molding, and a decorative molded product using the decorative sheet. [Solution] The light-transmitting decorative sheet (10) comprises a multilayer base sheet (20) in which a first polycarbonate resin layer (22) is disposed between a first acrylic resin layer (21) and a second acrylic resin layer (23), a gravure printing layer (30) having a pattern layer (31), a light-transmitting pattern layer (32) having a light-transmitting pattern, and a multilayer backer sheet (60). The multilayer backer sheet (60) includes a first backer sheet (40) made of ABS resin or polypropylene resin, and a second backer sheet (50) made of a third acrylic resin layer (51) and a second polycarbonate resin layer (52). The bottom layer of the multilayer backer sheet (60) is the second polycarbonate resin layer (52).

Description

Technical Field

[0001] The present invention relates to a light-transmissive decorative sheet, a method for manufacturing the light-transmissive decorative sheet, a decorated molded article, and a method for manufacturing the decorated molded article.

Background Art

[0002] Conventionally, for interior and exterior parts of vehicles, interior materials for building materials, home appliances, etc., decorated molded articles in which a decorative sheet is laminated on the surface of a resin molded article have been used. With the recent trend of consumers' pursuit of luxury and the multifunctionalization of products, there is a demand for decorated molded articles that transmit visible light. For example, in Patent Document 1, a multilayer film in which a polycarbonate resin layer is disposed between two acrylic resin layers, a gravure printing layer, a first backing film made of an ABS resin, a second backing film in which a polycarbonate resin is disposed between two acrylic resin layers, and a light transmission pattern layer are provided, and a decorative film for insert molding that transmits visible light is disclosed.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the decorative film for insert molding disclosed in Patent Document 1, due to the heat and pressure during injection molding, the second backing film may melt, and "backing flow" may occur, where traces of the melted and flowed backing remain on the resin molded article. Further, when manufacturing the decorative film for insert molding disclosed in Patent Document 1, when thermally laminating the multilayer film, the first backing film, and the second backing film, if the heating body directly touches the second backing film, the second backing film may melt. Therefore, it was necessary to provide a peeling film on the surface of the second backing film that comes into contact with the heating body.

[0005] The object of the present invention is to provide a light-transmitting decorative sheet that suppresses the melting of the backer film and the occurrence of backer flow during the manufacturing of decorative molded products. [Means for solving the problem]

[0006] To achieve the above objective, the first invention provides a light-transmitting decorative sheet comprising: a visible light-transmitting multilayer substrate sheet having a first main surface and a second main surface, with a first polycarbonate resin layer made of polycarbonate resin disposed between a first acrylic resin layer and a second acrylic resin layer made of acrylic resin; a visible light-transmitting gravure printing layer disposed on the side of the first main surface of the multilayer substrate sheet and having a pattern layer containing a gravure printing pattern; a multilayer backer sheet disposed on the opposite side of the gravure printing layer from the multilayer substrate sheet; and a light-transmitting pattern layer formed on the multilayer backer sheet or the multilayer substrate sheet and having a light-transmitting pattern that transmits visible light. The multilayer backer sheet includes a first backer sheet and a second backer sheet, the first backer sheet being made of ABS resin or polypropylene resin and being a visible light-transmitting sheet. The second backer sheet consists of a third acrylic resin layer made of acrylic resin and a second polycarbonate resin layer made of polycarbonate resin, and is positioned on the opposite side of the gravure printing layer of the first backer sheet, and is a sheet that transmits visible light. In a multilayer backer sheet, when the side on which the multilayer substrate sheet is placed is considered upwards, the second polycarbonate resin layer is positioned as the bottom layer of the multilayer backer sheet.

[0007] With this configuration, the second polycarbonate resin layer, made of heat-resistant polycarbonate resin, adheres to the molten resin during injection molding. This suppresses the melting of the multilayer backer sheet and the occurrence of backer flow during injection molding.

[0008] The second invention is the first invention wherein the ratio of the thickness of the resin layer made of polycarbonate resin in the multilayer backer sheet to the thickness of the multilayer backer sheet is 9% or more and 19% or less.

[0009] This configuration reduces the rigidity of the multilayer backer sheet, making it possible to provide a light-transmitting decorative sheet with excellent shapeability.

[0010] The third invention is that, in the first invention, the thickness of the multilayer backer sheet is 400 μm or more and 600 μm or less.

[0011] This configuration allows for both the flexibility of the multilayer backer sheet and the strength required for processing, thus providing a light-transmitting decorative sheet with excellent moldability.

[0012] The fourth invention is the first invention wherein the total light transmittance of the first backer sheet is 30% or more and 60% or less.

[0013] With this configuration, the first backer sheet diffuses light from the light source, making it difficult to see pinholes in the light-transmitting pattern layer and design layer, thus making the pinholes less noticeable.

[0014] The fifth invention further comprises, in the first invention, a matte layer formed on the second main surface of a multilayer substrate sheet and a matte pattern layer formed on the matte layer. The matte layer comprises a first binder resin and a first matte material, and the matte pattern layer comprises a second binder resin and a second matte material. The first binder resin and the second binder resin are two-component curable urethane resins which are cured products of a polyol and an isocyanate-based curing agent, and the ratio (NCO / OH) of isocyanate groups in the isocyanate-based curing agent to hydroxyl groups in the polyol is 1.1 to 2.0.

[0015] With this configuration, the appropriate cross-linking reaction of the two-component curable urethane resin forming the matte layer and the matte pattern layer proceeds, making it possible to provide a light-transmitting decorative sheet with excellent moldability and chemical resistance.

[0016] The sixth invention is a method for manufacturing a light-transmitting decorative sheet, comprising: a gravure printing step of forming a gravure-printed layer that transmits visible light on the first main surface of a multilayer substrate sheet by gravure printing; a thermal lamination step of thermally laminating a first backer sheet, a second backer sheet, and the multilayer substrate sheet on which the gravure-printed layer is formed; and a light-transmitting pattern layer formation step of forming a light-transmitting pattern that transmits visible light on the second backer sheet or the multilayer substrate sheet. In the gravure printing step, a gravure-printed layer that transmits visible light is formed on the first main surface of a multilayer substrate sheet on which a first polycarbonate resin layer made of polycarbonate resin is arranged between a first acrylic resin layer and a second acrylic resin layer made of acrylic resin and which transmits visible light. In the thermal lamination step, the first backer sheet and the second backer sheet are thermally laminated with the multilayer substrate sheet on which the gravure-printed layer is formed. The first backer sheet is made of an ABS resin or a polypropylene resin that transmits visible light. The second backer sheet consists of a third acrylic resin layer made of acrylic resin and a second polycarbonate resin layer made of polycarbonate resin, and transmits visible light. In the thermal lamination process, the second polycarbonate resin layer of the second backer sheet is in contact with the first contact heating element, the first backer sheet is in contact with the second backer sheet, and the multilayer substrate sheet on which the gravure printing layer is formed is in contact with the first backer sheet. The second backer sheet, the first backer sheet, and the multilayer substrate sheet are thermally laminated by heat supplied from the first contact heating element. In the light-transmitting pattern layer formation process, a light-transmitting pattern that transmits visible light is formed on the second backer sheet or the multilayer substrate sheet by gravure printing or screen printing.

[0017] In the manufacturing method of the light-transmitting decorative sheet configured in this way, the second polycarbonate resin layer, which has excellent heat resistance, comes into contact with the contact heating element during the thermal lamination process. Therefore, even if the contact heating element comes into direct contact with the multilayer backer sheet, backer flow is unlikely to occur. Since there is no need to prevent the contact heating element from coming into direct contact with the multilayer backer sheet, it can be manufactured without using a release film.

[0018] The seventh invention is a method for manufacturing a decorated molded product, comprising: a shaping step of forming a light-transmitting decorative sheet described in any of the first to fifth inventions into a three-dimensional shape; a trimming step of trimming and removing unnecessary parts of the light-transmitting decorative sheet; a step of setting the light-transmitting decorative sheet in a mold; and an injection molding step of injecting a polycarbonate-based resin into the mold to form a resin molded body, while simultaneously fixing the surface of the resin molded body to the second polycarbonate resin layer, which is the bottom layer of the multilayer backer sheet of the light-transmitting decorative sheet.

[0019] This manufacturing method allows for the production of decorative molded parts with complex shapes through insert molding and in-mold molding. Furthermore, the reduction in manufacturing steps leads to lower production costs and shorter production times.

[0020] The eighth invention is a decorative molded article comprising a resin molded article and a light-transmitting decorative sheet formed on the resin molded article. The light-transmitting decorative sheet includes a multilayer backer sheet, a multilayer base sheet formed on the multilayer backer sheet, a gravure printing layer formed on the multilayer base sheet side facing the multilayer backer sheet, and a light-transmitting pattern layer formed on the multilayer backer sheet or multilayer base sheet having a light-transmitting pattern that transmits visible light. The multilayer base sheet comprises an acrylic resin and a polycarbonate resin. The multilayer backer sheet comprises a first backer sheet and a second backer sheet. The first backer sheet is made of an ABS resin or a polypropylene resin and is a sheet that transmits visible light. The second backer sheet is a sheet made of a third acrylic resin layer made of an acrylic resin and a second polycarbonate resin layer made of a polycarbonate resin, with the second polycarbonate resin layer fixed to the resin molded article.

[0021] With this configuration, the second polycarbonate resin layer, which has excellent heat resistance, is fixed to the resin molded body, thus suppressing the melting of the multilayer backer sheet due to the heat during injection molding. As a result, a decorative molded product with a beautiful appearance can be obtained. [Effects of the Invention]

[0022] According to the present invention, it is possible to provide a light-transmissive decorative sheet in which the generation of a backing flow due to the melting of a backing sheet during injection molding is suppressed. Further, according to the method for manufacturing a light-transmissive decorative sheet according to the present invention, it is possible to suppress the occurrence of a backing flow during the manufacture of the light-transmissive decorative sheet without using a release sheet.

Brief Description of the Drawings

[0023] [Figure 1] It is a front view of a door of an automobile to which a light-transmissive decorative film according to the first embodiment of the present invention is applied. [Figure 2] It is a schematic cross-sectional view of a decorative molded article according to the first embodiment of the present invention. [Figure 3] It is a schematic cross-sectional view showing a method for manufacturing a decorative molded article according to the first embodiment of the present invention. [Figure 4] It is a schematic cross-sectional view of a light-transmissive decorative sheet according to the first embodiment of the present invention. [Figure 5] It is a schematic cross-sectional view showing an example of the configuration of a multilayer base material sheet on which a gravure printing layer is printed. [Figure 6] It is a schematic cross-sectional view for explaining a first thermal lamination step of thermally laminating a first backing sheet and a second backing sheet. [Figure 7] It is a schematic cross-sectional view for explaining a second thermal lamination step of thermally laminating the entire light-transmissive decorative sheet. [Figure 8] It is a schematic cross-sectional view of a decorative molded article according to the second embodiment of the present invention. [Figure 9] It is a schematic cross-sectional view of a light-transmissive decorative sheet according to the second embodiment of the present invention. [Figure 10] It is a schematic cross-sectional view showing an example of the configuration of a multilayer base material sheet on which a gravure printing layer is printed. [Figure 11] It is a schematic cross-sectional view for explaining a second thermal lamination step of thermally laminating the entire light-transmissive decorative sheet. [Figure 12] It is a schematic cross-sectional view showing another example of the configuration of a multilayer film on which a gravure printing layer is printed. [Figure 13] This is a schematic cross-sectional view showing another example of a multilayer backer sheet configuration. [Figure 14] This is a schematic diagram showing the step of cutting a component of a light-transmitting decorative sheet. [Modes for carrying out the invention]

[0024] A light-transmitting decorative sheet 10 according to the first embodiment of this invention will be described with reference to the figures.

[0025] <First Embodiment> (1) Application of light-transmitting decorative sheets Figures 1(a) and 1(b) show an automobile door 100 to which a light-transmitting decorative sheet is applied. As can be seen by comparing Figures 1(a) and 1(b), the door 100 is configured so that a five-stripe pattern 120 can be displayed in visible light on the inner door trim 110. This door trim 110 is a decorative molded product decorated with a light-transmitting decorative sheet. On the back side of the door trim 110 on which the pattern 120 is provided, a lighting device (not shown), such as an LED, which is controlled on and off by the automobile's system (not shown), is placed as a light source. The portion of the door trim 110 on which the pattern 120 is formed is manufactured, for example, by injection molding of a polycarbonate resin. The pattern 120 on the door 100 is formed on the door trim 110 by a light-transmitting decorative sheet, which will be described later. When light is supplied from the back of the door trim 110 by a lighting device, the five-stripe pattern 120, which is a light-transmitting design, is displayed by visible light. (1-1) Structure of molded product using light-transmitting decorative sheet As shown in Figure 2, the decorative molded product 12 has a structure in which a light-transmitting decorative sheet 10 is laminated on a resin molded body 11. The light-transmitting decorative sheet 10 comprises a multilayer base sheet 20, a gravure printing layer 30, a first backer sheet 40, and a second backer sheet 50. The gravure printing layer 30 has a pattern layer 31, a light-transmitting pattern layer 32, and an adhesive layer 33. The first figure 36 formed on the pattern layer 31 is placed at a predetermined position on the door trim 110, which is a decorative molded product having a three-dimensional shape. The light-transmitting pattern 37 of the light-transmitting pattern layer 32 is arranged so that visible light Li is transmitted around the first figure 36 or the area around the first figure 36. Each component of the light-transmitting decorative sheet 10 will be described later in the section "(3) Configuration of the light-transmitting decorative sheet 10".

[0026] (2) Method for manufacturing a decorated molded product using a light-transmitting decorative sheet The manufacturing method for the decorated molded product 12 will be explained with reference to Figure 3. First, the light-transmitting decorative sheet 10 is placed on the jig 92 and preheated using a heat source 91 (see Figure 3(a)). As the heat source 91, an infrared heater, electric heater, high-frequency induction, halogen lamp, microwave, high-temperature derivative such as steam, or a laser can be used. The temperature of the heat applied to the light-transmitting decorative sheet 10 by the heat source 91 can be 100 to 250°C. Next, the light-transmitting decorative sheet 10, which has been softened by heating, is pressed into contact with the jig 92 and shaped (see Figure 3(b)). As a method of pressing it into contact, for example, air can be drawn between the light-transmitting decorative sheet 10 and the jig 92 through a suction hole (not shown) provided in the jig 92, or compressed air can be sent from the decorative sheet 10 side to press the light-transmitting decorative sheet 10 into contact with the jig 92. Next, unnecessary parts of the light-transmitting decorative sheet 10 are trimmed (see Figure 3(c)). This makes it possible to obtain a light-transmitting decorative sheet 10 that is shaped to match the outer surface of the decorated molded product. For trimming, for example, a die-cutting machine or a laser is used. The trimmed decorative sheet 10 is placed on the cavity surface of the first mold 81 so that the multilayer backer sheet 60, described later, faces the cavity surface of the second mold 82. The light-transmitting decorative sheet 10 is fixed in place by a method such as sucking air from a suction hole (not shown) provided in the first mold 81 (see Figure 3(d)). Next, the first mold 81 and the second mold 82 are clamped together to form a cavity between the first and second molds, and molten resin is injected into the cavity from the gate 83 to form a resin molded body 11, at the same time as fixing the resin molded body 11 and the light-transmitting decorative sheet 10 (see Figure 3(e)). At this time, the surface of the resin molded body 11 is fixed to the second polycarbonate layer 52 of the light-transmitting decorative sheet 10. As the molten resin, the same resin as described above for the resin molded body 11 can be used, for example, a polycarbonate resin can be used. The general molding temperature (molten resin temperature) for resin molded bodies containing polycarbonate resin is 260°C to 320°C. The light-transmitting decorative sheet 10 of the first embodiment can be molded at a molding temperature of 300°C or higher. The mold is opened and the decorative molded product 12, in which the light-transmitting decorative sheet 10 and the resin molded body 11 are integrated, is removed (see Figure 3(f)).

[0027] In the above-described manufacturing method, the light-transmitting decorative sheet 10 was molded in close contact with the jig 92 and trimmed before injection molding. However, trimming of the light-transmitting decorative sheet 10 may also be performed after injection molding. In that case, the light-transmitting decorative sheet 10 can be molded in close contact with the molding surface of the first mold 81, the decorated molded product in which the light-transmitting decorative sheet 10 and the resin molded body 11 are integrated by injection molding can be removed, and the unnecessary portion of the light-transmitting decorative sheet 10 can be trimmed. As a method for ensuring close contact with the molding surface of the first mold 81, a method can be used in which air is sucked between the light-transmitting decorative sheet 10 and the molding surface through suction holes provided in the first mold 81. Furthermore, in the above-described manufacturing method, the gate 83 is located in the second mold 82, but the gate 83 may also be located in the first mold. Also, the light-transmitting decorative sheet 10 only needs to be positioned so that the second polycarbonate layer 52 faces the cavity surface of the mold where the gate is located, and may be positioned on either the cavity surface of the first mold 81 or the second mold 82. When referring to the bonding of the surface of the resin molded body 11 to the second polycarbonate resin layer 52, this includes the case where a light-transmitting pattern layer 71 or adhesive layer 72 is formed on the side of the second polycarbonate resin layer 52 that bonds to the resin molded body 11.

[0028] (3) Composition of the light-transmitting decorative sheet 10 As shown in Figure 4, the light-transmitting decorative sheet 10 comprises a multilayer base sheet 20, a gravure printing layer 30, a first backer sheet 40, and a second backer sheet 50. The first figure 36 formed on the pattern layer 31 of the gravure printing layer 30 is placed at a predetermined position on the door trim 110, which is a decorative molded product having a three-dimensional shape. The light-transmitting pattern 37 of the light-transmitting pattern layer 32 is positioned so that visible light Li passes through the first figure 36 or around the first figure 36. In other words, the light-transmitting pattern 37 is positioned so that visible light passes through predetermined locations of the pattern on the pattern layer 31. The light-transmitting pattern 37 is the pattern of the light-transmitting portion 32a, which will be described later. The misalignment between the first figure 36 and the light-transmitting pattern 37 is preferably ±0.6 mm or less. (3-1) Multilayer base sheet 20 The multilayer substrate sheet 20 has a first main surface 20a and a second main surface 20b. The multilayer substrate sheet 20 transmits visible light. The thickness of the multilayer substrate sheet 20 is, for example, 30 μm to 150 μm. A multilayer substrate sheet 20 with a thickness of 30 μm to 150 μm is suitable for gravure printing. In this first embodiment, the thickness of the multilayer substrate sheet 20 is set to, for example, 50 μm. The multilayer substrate sheet 20 has a first polycarbonate resin layer 22 disposed between a first acrylic resin layer 21 and a second acrylic resin layer 23. The exposed surface of the first acrylic resin layer 21 is the first main surface 20a, and the exposed surface of the second acrylic resin layer 23 is the second main surface 20b. The first acrylic resin layer 21 and the second acrylic resin layer 23 are made of acrylic resin. An example of the acrylic resin used in the first acrylic resin layer 21 and the second acrylic resin layer 23 is PMMA. In this disclosure, when the first acrylic resin layer 21 and the second acrylic resin layer 23 are made of acrylic resin, this includes not only cases where these layers are composed solely of acrylic resin, but also cases where additives are added to the acrylic resin. The first polycarbonate resin layer 22 is made of a polycarbonate resin. In the present invention, when the first polycarbonate resin layer 22 is made of a polycarbonate resin, this includes not only cases where the layer is made of only a polycarbonate resin, but also cases where additives are added to the polycarbonate resin. The thickness of the first polycarbonate resin layer 22 is preferably 10 μm to 105 μm. The glass transition temperature (Tg) of the first polycarbonate resin layer 22 is, for example, 120°C to 200°C. To obtain high heat resistance, a higher glass transition temperature (Tg) is preferable, preferably 150°C to 200°C, and more preferably 170°C to 200°C. The glass transition temperature (Tg) is measured in accordance with JIS 7121. Preferably, the multilayer substrate sheet 20 has a shrinkage rate during gravure printing that is kept within the range of -0.20% to +0.20% in both the feeding direction and the width direction of the multilayer substrate sheet 20, and more preferably, the shrinkage rate is kept within the range of -0.15% to +0.15%.

[0029] (3-2) Gravure printing layer 30 The gravure printing layer 30 is located on the side of the first main surface 20a of the multilayer substrate sheet 20. More specifically, the gravure printing layer 30 is formed by printing on the first main surface 20a (the exposed surface of the first acrylic resin layer 21) of the multilayer substrate sheet 20. The gravure printing layer 30 has a pattern layer 31, a light-transmitting pattern layer 32, and an adhesive layer 33. The pattern layer 31 and the light-transmitting pattern layer 32 are formed using conventional gravure inks. Gravure inks contain a binder resin, a solvent, and a colorant. Examples of binder resins include vinyl chloride vinyl acetate copolymer resin, acrylic resin, polyester resin, and polyurethane resin. The solvent is used to dissolve the resin and is selected according to the resin. Examples of solvents for gravure inks include toluene, methyl ethyl ketone, ethyl acetate, and isopropyl alcohol. The light-transmitting pattern layer 32 has a shielding portion 32b that blocks visible light formed by gravure printing, and the portion where the shielding portion 32b is not printed becomes the light-transmitting portion 32a. The light-transmitting pattern layer 32 is aligned with the design layer 31 during printing. This alignment allows visible light passing through the light-transmitting pattern layer 32 to pass through predetermined locations on the design layer 31. The adhesive layer 33 is a layer for bonding to the first backer sheet 40. The adhesive layer 33 is a layer that transmits visible light. Examples of adhesives that make up the adhesive layer 33 include vinyl chloride vinyl acetate copolymer resin, acrylic resin, polyester resin, and polyurethane resin.

[0030] (3-3) Multilayer backing sheet 60 The multilayer backer sheet 60 includes a first backer sheet 40 and a second backer sheet 50. The first backer sheet 40 and the second backer sheet 50 are bonded together by heat lamination. The first backer sheet 40 is made of a visible light-transmitting ABS resin or a visible light-transmitting polypropylene resin. Examples of visible light-transmitting ABS resins include visible light-transmitting ABS resin and visible light-transmitting MABS (methyl methacrylate-acrylonitrile-butadiene-styrene) resin. In this disclosure, when the first backer sheet 40 is made of a visible light-transmitting ABS resin, this includes not only cases where the sheet is made of ABS resin alone, but also cases where additives are added to the ABS resin, for example, a smoke-colored ABS resin in which a black pigment is added to the ABS resin. Examples of visible light-transmitting polypropylene resins include visible light-transmitting polypropylene. The total light transmittance of the first backer sheet 40 is preferably 30% or more and 60% or less. In this disclosure, total light transmittance refers to the value measured using a haze meter (manufactured by Nippon Denshoku Industries Co., Ltd.) in accordance with JIS K7361-1:1997, under the conditions of light source D65 and temperature 25°C. If the total light transmittance of the first backer sheet is 30% or more, the light-transmitting design is clearly displayed. If the total light transmittance of the first backer sheet is 60% or less, the light from the light source diffuses within the first backer sheet, making it difficult to visually inspect pinholes that may form in the light-transmitting pattern layer or design layer due to thermal damage during shaping or injection molding. The specific heat of the first backer sheet 40 is between 1.3 × 10³ J / (kg·K) and 1.7 × 10³ J / (kg·K). The specific heat measurement method is carried out in accordance with JIS K7123. A higher specific heat of the first backer sheet 40 is preferable because it can suppress the temperature rise of the gravure printing layer 30. However, if the specific heat is too high, the material will be difficult to heat up and soften, which may prevent proper adhesion between layers. The thickness of the first backer sheet 40 is, for example, 250 μm to 450 μm. From the viewpoint of reducing thermal damage during injection molding, the thickness of the first backer sheet 40 is preferably 300 μm to 450 μm, and more preferably 350 μm to 450 μm.

[0031] The second backer sheet 50 is positioned on the opposite side of the first backer sheet 40 from the multilayer substrate sheet 20. The thickness of the second backer sheet 50 is, for example, 40 μm to 200 μm. The second backer sheet 50 consists of a third acrylic resin layer 51 and a second polycarbonate resin layer 52 arranged in layers. The third acrylic resin layer 51 is made of an acrylic resin. An example of an acrylic resin used in the third acrylic resin layer 51 is PMMA. In this disclosure, when the third acrylic resin layer 51 is said to be made of an acrylic resin, this includes not only cases where these layers are made of acrylic resin alone, but also cases where additives are added to the acrylic resin. The second polycarbonate resin layer 52 is made of a polycarbonate-based resin. An example of the polycarbonate-based resin used in the second polycarbonate resin layer 52 is polycarbonate resin. In this disclosure, when the second polycarbonate resin layer 52 is said to be made of a polycarbonate-based resin, this includes not only cases where the layer is composed solely of polycarbonate-based resin, but also cases where additives are added to the polycarbonate-based resin. The thickness of the second polycarbonate resin layer 52 is, for example, 30 μm to 150 μm. To achieve both heat resistance and shapeability, the thickness of the second polycarbonate resin layer 52 is preferably 40 μm to 150 μm, and more preferably 40 μm to 100 μm. Furthermore, the glass transition temperature (Tg) of the first polycarbonate resin layer 22 is, for example, 120°C to 200°C. From the viewpoint of heat resistance, the glass transition temperature (Tg) is preferably 150°C to 200°C, and more preferably 170°C to 200°C. In a multilayer backer sheet, with the side containing the multilayer base sheet facing upwards, the second polycarbonate resin layer 52 is provided as the bottom layer of the multilayer backer sheet 60. During injection molding, the second polycarbonate resin layer, made of heat-resistant polycarbonate resin, adheres to the molten resin, thus suppressing the melting of the multilayer backer sheet by the heat generated during injection molding. The multilayer backer sheet may include sheets other than the first backer sheet 40 and the second backer sheet 50.

[0032] The thickness of the multilayer backer sheet 60 is preferably 400 μm to 600 μm from the viewpoint of achieving both flexibility and the strength required for processing. Furthermore, the ratio of the thickness of the polycarbonate resin layer in the multilayer backer sheet to the thickness of the multilayer backer sheet is preferably 5% to 19%, and more preferably 5% to 13%. If it is 5% or more, the multilayer backer sheet can be given the strength required for processing. If it is 19% or less, the formability can be improved, making it easier to form even with a vacuum forming machine with low suction capacity. Improved formability allows for forming at low temperatures, reducing the thermal damage to the light-transmitting decorative sheet during forming, and thus suppressing the occurrence of pinholes. In particular, if it is 13% or less, the specific heat of the multilayer backer sheet increases, suppressing the temperature rise of the multilayer backer sheet during forming and injection molding, and thus suppressing the occurrence of pinholes in the light-transmitting pattern layer and design layer of gravure printing during forming and injection molding.

[0033] (4) Method for manufacturing the light-transmitting decorative sheet 10 of the first embodiment An example of a method for manufacturing the light-transmitting decorative sheet 10 is shown in Figures 5 to 7. The method for manufacturing the light-transmitting decorative sheet 10 comprises a gravure printing step, a thermal lamination step, and a light-transmitting pattern layer formation step. As shown in Figure 5, in the gravure printing step, a gravure printed layer 30 is formed on the first main surface 20a side of the multilayer substrate sheet 20 by gravure printing. First, a pattern layer 31 is printed on the multilayer substrate sheet 20 by gravure printing. Next, in the light-transmitting pattern layer formation step, the pattern layer 31 is aligned, and a shielding portion 32b is printed by gravure printing to form a light-transmitting pattern layer 32 that transmits visible light at a predetermined location on the pattern layer 31. In other words, the light-transmitting portion 32a of the light-transmitting pattern layer 32 is formed at a predetermined location on the pattern layer 31. Furthermore, an adhesive is printed on the light-transmitting pattern layer 32 by gravure printing to form an adhesive layer 33. In the gravure printing process, after printing the gravure printing layer 30, heat treatment is performed at a temperature higher than the evaporation temperature of the solvent in the gravure ink used to form the gravure printing layer 30. This heat treatment reduces the residual solvent in the gravure ink compared to before the heat treatment. The thermal lamination process includes a first thermal lamination step shown in Figure 6 and a second thermal lamination step shown in Figure 7. In the first heat lamination step, the first backer sheet 40 is brought into contact with the heating drum 420, which is a second contact heating element, and the second backer sheet 50 is brought into contact with the first backer sheet 40. The first backer sheet 40 and the second backer sheet 50 are then heat-laminated to form a multilayer backer sheet 60 (see Figure 6). The temperature of the heating drum 420 is, for example, 170°C. Heat is transferred from the heating drum 420 to the second backer sheet 50 via the first backer sheet 40. In the first heat lamination step, since the first backer sheet 40 is in contact with the heating drum 420, the first backer sheet 40 does not strongly adhere to the heating drum 420 during heat lamination.

[0034] In the second heat lamination step, the multilayer backer sheet 60 and the multilayer base sheet 20 are heat-laminated by heat supplied from the heating drum 410, which is the first contact heating element. The temperature of the heating drum 410 is, for example, 170°C. The heating drum 410 is brought into contact with the surface of the multilayer backer sheet 60 on which the second polycarbonate resin layer 52 is located, and heat lamination is performed with the multilayer base sheet 20, on which the gravure printing layer 30 is formed, in contact with the first backer sheet 40 of the multilayer backer sheet 60. In the second heat lamination step, since the second polycarbonate resin layer, which has excellent heat resistance, is in contact with the contact heating element, backer flow is unlikely to occur even if the contact heating element directly contacts the multilayer backer sheet. Since there is no need to prevent the contact heating element from directly contacting the multilayer backer sheet, manufacturing can be done without using a release sheet. The same drum may be used for heating drum 410 and heating drum 420. Furthermore, although heating drum 410 was used for the first contact heating element and heating drum 420 for the second contact heating element in this example, heating drums are not the only suitable components for the first and second contact heating elements. The first and second contact heating elements can be any components capable of applying heat and pressure to the sheet being laminated while in contact with it. <Second Embodiment>

[0035] (5) Application of light-transmitting decorative sheets The light-transmitting decorative sheet 10 of the second embodiment, like the light-transmitting decorative sheet of the first embodiment, can be applied to, for example, an automobile door 100. (5-1) Structure of molded product using light-transmitting decorative sheet As shown in Figure 8, the decorative molded product 12 has a structure in which a light-transmitting decorative sheet 10 is laminated on a resin molded body 11. The light-transmitting decorative sheet 10 comprises a multilayer base sheet 20, a gravure printing layer 30, a first backer sheet 40, a second backer sheet 50, and a screen printing layer 70. The gravure printing layer 30 has a pattern layer 31 and an adhesive layer 33. The screen printing layer 70 has a light-transmitting pattern layer 71 and an adhesive layer 72. The first figure 36 formed on the pattern layer 31 is placed at a predetermined position on the door trim 110, which is a decorative molded product having a three-dimensional shape. The light-transmitting pattern 77 of the light-transmitting pattern layer 71 is arranged so that visible light Li is transmitted around the first figure 36 or the area surrounding the first figure 36. Each component of the light-transmitting decorative sheet 10 will be described later in the section "(7) Configuration of the light-transmitting decorative sheet 10". (6) Method for manufacturing a decorated molded product using a light-transmitting decorative sheet The decorated molded product using the light-transmitting decorative sheet of the second embodiment can also be manufactured in the same way as the first embodiment, for example, by the method for manufacturing a decorated molded product shown in Figure 3.

[0036] (7) Composition of the light-transmitting decorative sheet 10 As shown in Figure 9, the light-transmitting decorative sheet 10 comprises a multilayer substrate sheet 20, a gravure printing layer 30, a first backer sheet 40, a second backer sheet 50, and a screen printing layer 70. In the light-transmitting decorative sheet 10 of the second embodiment, the first figure 36 formed on the pattern layer 31 of the gravure printing layer 30 is positioned at a predetermined location on the door trim 110, which is a decorative molded product having a three-dimensional shape. The light-transmitting pattern 77 of the light-transmitting pattern layer 71 is positioned so that visible light Li passes through the first figure 36 or around the first figure 36. In other words, the light-transmitting pattern 77 is positioned so that visible light passes through predetermined locations of the pattern on the pattern layer 31. The light-transmitting pattern 77 is the pattern of the light-transmitting portion 71a, which will be described later. The misalignment between the first figure 36 and the light-transmitting pattern 77 is preferably ±5 mm or less. (7-1) Multilayer substrate sheet 20 The multilayer substrate sheet 20 of the second embodiment has the same configuration as the multilayer substrate sheet 20 of the first embodiment. Therefore, a description of the configuration of the multilayer sheet 20 of the second embodiment will be omitted here. (7-2) Gravure printing layer 30 The gravure printing layer 30 of the second embodiment is also located on the side of the first main surface 20a of the multilayer sheet 20. More specifically, the gravure printing layer 30 is formed by printing on the first main surface 20a (the exposed surface of the first acrylic resin layer 21) of the multilayer sheet 20. The gravure printing layer 30 has a pattern layer 31 and an adhesive layer 33. Compared to the gravure printing layer 30 of the first embodiment, the gravure printing layer 30 of the second embodiment does not have a light-transmitting pattern layer 32. In the gravure printing layer 30 of the second embodiment, the pattern layer 31 and the adhesive layer 33 are adjacent to each other. In other words, after the pattern layer 31 is formed on the multilayer sheet 20, the adhesive layer 33 is printed on the pattern layer 31. Since the pattern layer 31 and adhesive layer 33 of the second embodiment are the same as those of the pattern layer 31 and adhesive layer 33 of the first embodiment, a description of the pattern layer 31 and adhesive layer 33 of the second embodiment will be omitted here. (7-3) Multilayer backing sheet 60 The light-transmitting decorative sheet 10 of the second embodiment also has a multilayer backer sheet 60. The multilayer backer sheet 60 of the second embodiment also includes a first backer sheet 40 and a second backer sheet 50, similar to the multilayer backer sheet of the first embodiment. Since the first backer sheet 40 and the second backer sheet 50 of the second embodiment are the same as the first backer sheet 40 and the second backer sheet 50 of the first embodiment, a description of the multilayer backer sheet 60 of the second embodiment will be omitted here. (7-4) Screen printing layer 70 The screen-printed layer 70 is located on the side of the second polycarbonate resin layer 52 of the second backer sheet 50 of the multilayer backer sheet 60. More specifically, the screen-printed layer 70 is formed by printing on the exposed surface of the second polycarbonate resin layer 52. The screen-printed layer 70 has a light-transmitting pattern layer 71 and an adhesive layer 72. The light-transmitting pattern layer 71 is formed using conventional screen printing inks. Screen printing inks contain a binder resin, a solvent, and a colorant. Examples of binder resins include vinyl chloride vinyl acetate copolymer resin, acrylic resin, polyester resin, and polyurethane resin. The solvent is used to dissolve the resin and is selected according to the resin. Examples of solvents for screen printing inks include toluene, methyl ethyl ketone, ethyl acetate, and isopropyl alcohol. The light-transmitting pattern layer 71 has a shielding portion 71b that blocks visible light formed by screen printing, and the portion where the shielding portion 71b is not printed becomes the light-transmitting portion 71a. The light-transmitting pattern layer 71 is aligned with the pattern layer 31 that forms the gravure printing layer during printing. This alignment allows visible light passing through the light-transmitting pattern layer 71 to pass through predetermined locations on the pattern layer 31. The adhesive layer 72 is a layer for bonding with the resin molded article. The adhesive layer 72 is a layer that transmits visible light. Examples of adhesives that make up the adhesive layer 72 include vinyl chloride vinyl acetate copolymer resin, acrylic resin, polyester resin, and polyurethane resin. In this disclosure, when referring to the bonding of the surface of the resin molded article to the second polycarbonate resin layer 52, it also includes cases where a light-transmitting pattern layer 71 or an adhesive layer 72 is formed on the second polycarbonate resin layer 52.

[0037] (8) Method for manufacturing the light-transmitting decorative sheet 10 of the second embodiment An example of a manufacturing method for the light-transmitting decorative sheet 10 of the second embodiment is shown in Figures 10 to 11. Similar to the first embodiment, the manufacturing method for the light-transmitting decorative sheet 10 of the second embodiment also comprises a gravure printing step, a thermal lamination step, and a light-transmitting pattern layer formation step. Figures 10 and 11 show a cross-section of a portion of a long sheet. First, as shown in Figure 10, in the gravure printing step, a gravure printing layer 30 is formed on the first main surface 20a side of the multilayer substrate sheet 20 by gravure printing. First, a pattern layer 31 is printed on the multilayer substrate sheet 20 by gravure printing. Next, an adhesive is printed on the pattern layer 31 by gravure printing to form an adhesive layer 33. In the gravure printing process, after printing the gravure printing layer 30, heat treatment is performed at a temperature higher than the evaporation temperature of the solvent in the gravure ink used to form the gravure printing layer 30. This heat treatment reduces the residual solvent in the gravure ink compared to before the heat treatment. The thermal lamination process includes a first thermal lamination step shown in Figure 6 and a second thermal lamination step shown in Figure 11, similar to the first embodiment. In the first heat lamination step, the first backer sheet 40 comes into contact with the heating drum 420, which is the second contact heating element, and the second backer sheet 50 comes into contact with the first backer sheet 40. In this state, the first backer sheet 40 and the second backer sheet 50 are heat-laminated to form a multilayer backer sheet 60 (see Figure 11). The temperature of the heating drum 420 is, for example, 170°C.

[0038] As shown in Figure 11, in the second heat lamination step of the second embodiment, the multilayer backer sheet 60 and the multilayer base sheet 20 are heat-laminated by heat supplied from the heating drum 410, which is the first contact heating element, similar to the second lamination step of the first embodiment. The temperature of the heating drum 410 is, for example, 170°C. The heating drum 410 is brought into contact with the surface of the multilayer backer sheet 60 on which the second polycarbonate resin layer 52 is placed, and heat lamination is performed with the multilayer base sheet 20, on which the gravure printing layer 30 is formed, in contact with the first backer sheet 40 of the multilayer backer sheet 60. The second heat lamination step of the second embodiment is carried out in the same way as the second lamination step of the first embodiment, except that the configuration of the gravure printing layer 30 is different. Immediately after heat lamination, the component 11 is in a state similar to the roll 500 shown in Figure 14. In the next step, as shown in Figure 14, a sheet 510 of component 11 is created from the roll 500 of component 11. For example, slitting or cutting is used to create the sheet 510. In other words, the long component 11 of the roll 500 is cut into short sheets 510 of a predetermined length. In the next step of forming the light-transmitting pattern layer, a screen-printed layer 70 is formed on the second backer sheet 50. Using conventional screen printing inks, a light-transmitting pattern layer 71 is printed on the second polycarbonate resin layer 52 of the second backer sheet 50 by screen printing. In the light-transmitting pattern layer 71, a shielding portion 71b that blocks visible light is formed by screen printing, and the portion where the shielding portion 71b is not printed becomes the light-transmitting portion 71a. When printing the light-transmitting pattern layer 71, alignment of the pattern of the light-transmitting pattern layer 71 with the design layer 31 is performed. Furthermore, an adhesive layer 72 is printed on the light-transmitting pattern layer 71 by screen printing. Materials used to form the adhesive layer 72 include, for example, vinyl chloride vinyl acetate copolymer resin, polyester resin, and acrylic resin.

[0039] (9) Variant (9-1) Variation A In the first and second embodiments described above, the case in which the surface (second main surface 20b) of the multilayer film 20 is exposed was explained. However, as shown in Figure 12, a matte layer 24 and a matte pattern layer 25 that transmit visible light may be provided as surface layers on the second main surface 20b of the multilayer film 20. Openings may be provided in the matte layer 24 and the matte pattern 25 in order to transmit visible light. The matte layer 24 is a layer that gives the light-transmitting decorative sheet 10 a three-dimensional appearance due to the difference in gloss and uneven shape compared to the matte pattern layer 25. The matte pattern layer 25 is partially provided on top of the matte layer 24. Therefore, the matte pattern layer 25 is the outermost layer of the light-transmitting decorative sheet 10 in the areas where the matte pattern layer 25 is provided, and the matte layer 24 is the outermost layer in the areas where the matte pattern layer 25 is not provided. The matte layer 24 contains a first binder resin and a first matting agent, and the matte pattern layer 25 contains a second binder resin and a second matting agent. The first binder resin and the second binder resin are thermosetting resins, specifically two-component curable urethane resins. Two-component curable urethane resins are resins that are cured by adding an isocyanate curing agent to a polyol main component, and forming a cross-linked structure by the generation of urethane bonds between the hydroxyl groups in the polyol and the isocyanate groups in the isocyanate curing agent. There are no particular limitations on the two-component curable urethane resin, but examples include those containing a polyol component having hydroxyl groups as the main component (acrylic polyol, polyester polyol, polyether polyol, epoxy polyol, etc.) and an isocyanate component as the curing agent (toluylene diisocyanate, hexamethylene diisocyanate, metaxylene diisocyanate, etc.). Of these, from the viewpoint of achieving both light resistance and processability, it is preferable to use acrylic polyol as the main component and metaxylene diisocyanate as the curing agent. Furthermore, the first binder resin and the second binder resin may be two-component curable urethane resin used alone, or a two-component curable urethane resin may be mixed with other resins. Examples of other resins include acrylic resins, urethane resins, thermoplastic polyester resins, and nitrated cotton. Plasticizers, stabilizers, catalysts, and curing agents may also be added as appropriate.

[0040] The NCO / OH ratio, which is the ratio of isocyanate groups in the isocyanate-based curing agent to hydroxyl groups in the polyol, of the two-component curable urethane resins forming the first and second binder resins is 1.1 to 2.0. If the NCO / OH ratio is 2.0 or less, excessive crosslinking reaction is suppressed, the hardness of the matte layer does not become too high, and the decorative sheet becomes less prone to cracking during three-dimensional molding. On the other hand, if the NCO / OH ratio is 1.1 or higher, the crosslinking reaction is promoted, improving the chemical resistance of the matte layer. By appropriately advancing the crosslinking reaction of the two-component curable urethane resin, a light-transmitting decorative sheet with excellent moldability and chemical resistance can be provided. Note that the main component and curing agent of the second binder resin and the first binder resin may be the same or different. Also, the NCO / OH ratio may be the same or different.

[0041] Examples of the first matting material include inorganic particles and resin particles. The matting material allows for adjustment of gloss and creates a gloss difference between the matting layer 24 and the matting pattern layer 25. It also improves scratch resistance. As inorganic particles, amorphous silica, spherical silica, alumina, kaolinite, calcium carbonate, barium sulfate, glass, etc., can be used. Of these, amorphous silica is preferred from the viewpoint of scratch resistance and printability. Inorganic particles may be used individually or in combination of two or more types. The particle size of the inorganic particles used as the first matting agent is preferably 1 μm to 10 μm, and more preferably 2 μm to 8 μm. If the particle size is 1 μm or larger, some of the inorganic particles are easily exposed from the surface of the layer, resulting in a good matting effect. If the particle size is 2 μm or larger, scratch resistance is improved. If the particle size is 10 μm or smaller, moldability is excellent, and if the particle size is 8 μm or smaller, the inorganic particles are distributed across the entire surface, resulting in a good matting effect and improved scratch resistance. In this disclosure, the average particle diameter is a volume-based average arithmetic value obtained by laser diffraction and scattering, and includes not only the primary particle diameter but also the secondary particle diameter, which is an aggregate of particles. The inorganic particle content is not particularly limited, but in the first matting agent, it is preferably 20 parts by mass or more and 70 parts by mass or less, and more preferably 40 parts by mass or more and 60 parts by mass or less, per 100 parts by mass of the first binder resin described above. If it is 20 parts by mass or more, improved scratch resistance can be obtained. If it is 40 parts by mass or more, the inorganic particles will spread throughout the entire surface and a good matting effect can be obtained. If it is 70 parts by mass or less, the occurrence of cracks during shaping will be suppressed, and if it is 60 parts by mass or less, good moldability will be maintained. As resin particles, organic beads such as urethane resin, acrylic resin, polycarbonate resin, polyamide (nylon) resin, urea resin, and silicon resin can be used. Resin particles may be used individually or in combination of two or more types. The average particle size of the resin particles can be in the range of 5 μm to 30 μm, for example. The resin particle content is not particularly limited, but for example, in the first matte material, it can be in the range of 5 parts by mass or more and 25 parts by mass or less per 100 parts by mass of the first binder resin mentioned above. If it is 5 parts by mass or more, it will be easy to feel, and if it is 25 parts by mass or less, good moldability will be obtained. Examples of the second matting material include inorganic particles and resin particles, and the same material as the first matting material of the matting layer 24 can be used. It is preferable that the second matting material contains resin particles. Resin particles can improve tactile feel and scratch resistance. The particle size of the resin particles used as the second matting agent is preferably 5 μm to 50 μm, and more preferably 10 μm to 30 μm, from the viewpoint of printability and tactile feel. If the particle size is 5 μm or larger, a good matting effect can be obtained. If it is 10 μm or larger, some of the resin particles will be exposed from the surface of the matting layer, resulting in a good tactile feel. Furthermore, if the particle size is 50 μm or smaller, a good coating film appearance can be obtained, and if it is 30 μm or smaller, the resin particles will be distributed across the entire surface, resulting in a good matting effect and improved scratch resistance. The content of resin particles is not particularly limited, but in the second matting agent, from the viewpoint of imparting tactile properties, it is preferable that the content be 5 parts by mass or more and 30 parts by mass or less, and more preferably 10 parts by mass or more and 20 parts by mass or less, per 100 parts by mass of the second binder resin. If it is 5 parts by mass or more, improved scratch resistance is obtained, if it is 10 parts by mass or more, the resin particles spread throughout the entire surface, and a good matting effect and tactile properties are obtained. If it is 30 parts by mass or less, cracking during shaping is suppressed, and if it is 20 parts by mass or less, good moldability is maintained. Instead of the matte layer 24 and the matte pattern layer 25, other pattern layers may be formed on the second main surface 20b of the multilayer film 20 by gravure printing. In this case, it is preferable that the gravure printed layer formed on the second main surface 20b of the multilayer film 20 is formed at the same time as the gravure printed layer 30 formed on the first main surface 20a. Furthermore, it is preferable that the second figure of the pattern layer formed on the second main surface 20b of the multilayer film 20 is positioned based on the first figure 36 of the pattern layer 31 of the gravure printed layer 30 formed on the first main surface 20a.

[0042] (9-2) Variation B In the first and second embodiments described above, the case in which the multilayer backer sheet 60 is composed of a first backer sheet 40 and a second backer sheet 50 was described. However, the multilayer backer sheet 60 may include sheets other than the first backer sheet 40 and the second backer sheet 50, as long as the second polycarbonate resin layer 52 of the second backer sheet 50 is the bottom layer. For example, as shown in Figure 13(a), a third backer sheet 61 may be placed between the first backer sheet 40 and the second backer sheet 50. Also, as shown in Figure 13(b), a multilayer backer sheet 62 consisting of a fourth backer sheet 63 and a fifth backer sheet 64 may be placed between the first backer sheet 40 and the second backer sheet 50. The materials for the third backer sheet 61, the fourth backer sheet 63, and the fifth backer sheet 64 can be the same as the materials used for the first or second backer sheet.

[0043] (9-3) Modification C In the first and second embodiments described above, a case was described in which the heat lamination process for manufacturing the light-transmitting decorative sheet 10 is configured to include a first heat lamination step (see Figure 6) and a second heat lamination step (see Figure 7 or Figure 11). However, if the feed rolls are three-axis, the heat lamination process may be configured such that, in a single heat lamination, the second polycarbonate resin layer 52 of the second backer sheet 50 comes into contact with the heating drum 410, the first backer sheet 40 comes into contact with the second backer sheet 50, and the multilayer sheet 20 on which the gravure printing layer 30 is formed comes into contact with the first backer sheet 40, and the second backer sheet 50, the first backer sheet 40, and the multilayer sheet 20 are heat-laminated by the heat supplied from the heating drum 410. The difference from the manufacturing method of the light-transmitting decorative sheet 10 in the first embodiment is that the first backer sheet 40 and the second backer sheet 50 remain separated until the heat lamination in which the heating drum 410 comes into contact with the second backer sheet 50.

[0044] (9-4) Modification D In the second embodiment described above, the case in which a screen-printed layer 70 is formed by screen printing after cutting the sheet 510 into individual sheets was explained. However, the screen printing for forming the screen-printed layer may also be performed using a roll-to-roll method. In the roll-to-roll method as well, a light-transmitting pattern layer 71 is printed on the second polycarbonate resin layer 52 of the second backer sheet 50 by screen printing. Furthermore, in the roll-to-roll method, an adhesive layer 72 is printed on the light-transmitting pattern layer 71 by screen printing.

[0045] (9-5) Modification E Furthermore, although the decorated molded product according to the first embodiment described above was manufactured by simultaneously molding the resin molded body 21 and laminating the decorative sheet 10, these processes may be carried out separately. In other words, the preformed decorative sheet 10 may be bonded to the molded resin molded body 21.

[0046] Furthermore, the light-transmitting decorative sheet or decorative molded product disclosed herein may be applied to applications other than automobile door rims. Furthermore, in the light-transmitting decorative sheet or decorative molded article of this disclosure, the adhesive layer 32 or adhesive layer 72 can have any configuration.

[0047] (10) Features (10-1) In the light-transmitting decorative sheet 10 described above, the multilayer sheet 20 has a configuration in which a first polycarbonate resin layer 22 is arranged between a first acrylic resin layer 21 and a second acrylic resin layer 23, and the second backer sheet 50 has a configuration in which a third acrylic resin layer 51 and a second polycarbonate resin layer 52 are arranged. In this light-transmitting decorative sheet 10, the multilayer structure of the multilayer sheet 20 and the second backer sheet 50 suppresses the shrinkage of the material during printing and drying when forming the gravure printing layer 30 to, for example, ±0.15%, and also suppresses the shrinkage of the material during heat lamination. As a result, the dimensional accuracy of the gravure printing pattern layer 31 and the light-transmitting pattern layer 32, or the dimensional accuracy of the gravure printing pattern layer 31 and the screen printing light-transmitting pattern layer 71 is improved. Furthermore, the heat resistance of the multilayer backer sheet 60 is improved by including a second backer sheet 50 having a multilayer structure and arranging a second polycarbonate resin layer 52 at the bottom layer of the multilayer backer sheet 60. As a result, even when molten resin reaching, for example, around 300°C comes into contact with the light-transmitting decorative sheet 10 during the manufacturing of the decorative molded product 12, the backer flow of the multilayer backer sheet and the ink flow of gravure printing can be suppressed. In addition, in this light-transmitting decorative sheet 10, the heat damage to the gravure ink can be reduced because the first backer sheet 40 is made of ABS resin or polypropylene resin. Furthermore, the strength of the light-transmitting decorative sheet 10 is improved by the second polycarbonate resin layer 52, making it less likely for cracks to occur in the light-transmitting decorative sheet 10 during shaping and molding. Backer flow or ink flow refers to the phenomenon where high temperatures cause the backer sheet or the resin used for printing to melt, leaving a trace of the molten backer on the molded resin product.

[0048] (10-2) When the ratio of the thickness of the polycarbonate resin layer in the multilayer backer sheet to the total thickness of the light-transmitting decorative sheet 10 described above is 5% to 19%, a light-transmitting decorative sheet can be obtained that achieves both the strength necessary for processing and good formability. This makes it possible to form the sheet using a vacuum forming machine with low suction capacity. The improved formability allows for forming at lower temperatures, reducing the thermal damage inflicted on the light-transmitting decorative sheet during forming. In particular, when the ratio is 5% to 13%, the specific heat of the multilayer backer sheet increases, suppressing the temperature rise of the multilayer backer sheet and preventing the occurrence of pinholes in the light-transmitting pattern layer or design layer of gravure printing during forming or injection molding.

[0049] (10-3) When the thickness of the multilayer backer sheet 60 of the light-transmitting decorative sheet 10 described above is between 400 μm and 600 μm, it is possible to achieve both the strength required for processing and good formability. If the thickness is 400 μm or more, the strength required for processing is obtained, and if it is 600 μm or less, good formability is obtained.

[0050] (10-4) When the total light transmittance of the first backer sheet 40 of the light-transmitting decorative sheet 10 described above is between 30% and 60%, the first backer sheet diffuses the light from the light source, making it difficult to see pinholes that may form in the light-transmitting pattern layer or design layer due to thermal damage during shaping or injection molding.

[0051] (10-5) When a matte layer 24 and a matte pattern 25 that transmit visible light are provided as surface layers on the second main surface 20b of the multilayer film 20 of the light-transmitting decorative sheet 10 described above, a three-dimensional feel and tactile feel can be imparted to the light-transmitting decorative sheet. In particular, when the matte layer contains a first binder resin and a first matte material, and the matte pattern layer contains a second binder resin and a second matte material, and the first and second binder resins are two-component curable urethane resins which are cured products of a polyol and an isocyanate-based curing agent, and the ratio of isocyanate groups in the isocyanate-based curing agent to hydroxyl groups in the polyol (NCO / OH) is 1.1 to 2.0, an appropriate cross-linking reaction of the two-component curable urethane resins forming the matte layer and the matte pattern layer proceeds, resulting in a light-transmitting decorative sheet with excellent moldability and chemical resistance.

[0052] (10-6) The glass transition temperature of the polycarbonate resin in the first polycarbonate resin layer 22 and the second polycarbonate resin layer 52 of the light-transmitting decorative sheet 10 described above is between 120°C and 200°C. Because the glass transition temperature of the polycarbonate resin in the first polycarbonate resin layer 22 and the second polycarbonate resin layer 52 is high, the heat resistance of the multilayer sheet 20 and the multilayer backer sheet 60 is improved. The gravure printing layer 30 sandwiched between the multilayer sheet 20 and the multilayer backer sheet 60, which have such improved heat resistance, is less prone to ink flow in the gravure printing layer 30 even when inserted during the manufacturing of the decorative molded product 12 in which molten polycarbonate resin at around 300°C is injected.

[0053] (10-7) The first backer sheet 40 of the light-transmitting decorative sheet 10 described above is configured to have a specific heat of 1.3 × 10³ J / (kg·K) or more and 1.7 × 10³ J / (kg·K) or less. By increasing the specific heat of the first backer sheet 40 in this way, damage to the gravure printing layer caused by heat can be reduced.

[0054] (10-8) In the light-transmitting decorative sheet 10 of the first embodiment described above, if the light-transmitting pattern layer 32 is included in the gravure printing layer 30, shrinkage of the material during the formation of the gravure printing layer 30 and during heat lamination is suppressed. As a result, the dimensional accuracy of the light-transmitting pattern layer 32 of the gravure printing layer 30 is improved.

[0055] (10-9) In the light-transmitting decorative sheet of the second embodiment described above, if the light-transmitting pattern layer 71 is formed on the second backer sheet 50, the light-transmitting pattern layer 71 is formed after heat lamination. As a result, the light-transmitting pattern layer 71 is prevented from being affected by heat lamination.

[0056] (10-10) In the manufacturing method of the light-transmitting decorative sheet 10 of the first or second embodiment described with reference to Figures 5 to 7 or Figures 10 to 11, the second polycarbonate resin layer 52 of the second backer sheet 50 comes into contact with the heating drum 410, which is the first contact heating element, during the heat lamination process (see Figure 7 or Figure 11). Since the second polycarbonate resin layer 52 has excellent heat resistance, even if the heating drum 410 comes into direct contact with the multilayer backer sheet 60, the melting of the backer sheet can be suppressed. Therefore, the light-transmitting decorative sheet 10 can be manufactured without using a release film. (10-11) The manufacturing method for the light-transmitting decorative sheet 10 of the first or second embodiment, as described with reference to Figures 5 to 7 or Figures 10 to 11, is configured to include a first thermal lamination step (see Figure 6) and a second thermal lamination step (see Figure 7 or Figure 11). By separating the lamination steps, the number of feed rolls used in the laminator can be reduced.

[0057] (10-12) In the manufacturing method of the light-transmitting decorative sheet 10 described above, the gravure printing process may include a heat treatment at a temperature higher than the evaporation temperature of the solvent of the gravure ink used to form the gravure printing layer 30 after printing the gravure printing layer 30. When such a heat treatment is performed, the residual solvent in the gravure printing layer 30 can be reduced, and foaming during shaping can be suppressed. (10-13) In the manufacturing method of the decorated molded product 12 described with reference to Figure 3, the multilayer backer sheet 60 includes a second backer sheet 50 having a multilayer structure, and in the multilayer backer sheet, when the side on which the multilayer base sheet is placed is considered upward, the second polycarbonate resin layer 52 is placed at the bottom layer of the multilayer backer sheet, thereby improving the heat resistance of the multilayer backer sheet 60. As a result, when manufacturing the decorated molded product 12 in which molten resin at around 300°C is injected, even if molten resin reaching around 300°C comes into contact with the light-transmitting decorative sheet 10, the backer flow of the multilayer backer sheet and the ink flow of gravure printing are suppressed. Furthermore, since the first backer sheet 40 is made of ABS resin or polypropylene resin, heat damage to the gravure printing layer 30 gravure ink can be reduced. Although the first and second embodiments of the present invention have been described above, the present invention is not limited to the first and second embodiments, and various modifications are possible without departing from the spirit of the invention. In particular, the multiple embodiments and modifications described herein can be arbitrarily combined as needed. [Examples]

[0058] (Example 1) A multilayer substrate sheet was prepared, consisting of a sheet in which a first polycarbonate resin layer made of polycarbonate resin was placed between a first acrylic resin layer and a second acrylic resin layer made of acrylic resin (first acrylic resin layer: 15 μm, first polycarbonate resin layer: 20 μm, second acrylic resin layer: 15 μm). A gravure printed layer was formed on one surface of the multilayer substrate sheet by laminating in the following order using gravure printing: a pattern layer made of acrylic resin / vinyl chloride-vinyl acetate copolymer (thickness: 2-5 μm), a light-transmitting pattern layer made of acrylic resin / vinyl chloride-vinyl acetate copolymer (thickness: 2-5 μm), and an adhesive layer made of vinyl chloride-vinyl acetate copolymer (thickness: 2-5 μm). Next, a multilayer backer sheet consisting of a first backer sheet and a second backer sheet was prepared. As the first backer sheet, a sheet made of ABS resin that transmits visible light (thickness: 380 μm) was prepared. As the second backer sheet, a sheet was prepared in which a third acrylic resin layer made of acrylic resin (thickness: 60 μm) and a second polycarbonate resin layer made of polycarbonate resin (thickness: 140 μm) were arranged. The first backer sheet was laminated onto the surface of the third acrylic resin layer of the second backer sheet to form a multilayer backer sheet. A multilayer substrate sheet was laminated on top of the multilayer backer sheet so that the adhesive layer of the gravure printing layer was in contact with the first backer sheet side of the multilayer backer sheet, and a light-transmitting decorative sheet was created.

[0059] (Examples 2-4) Using a sheet with a different film thickness than that of Example 1 (Table 1), a light-transmitting decorative sheet having the layer structure shown in Figure 4 was prepared using the same method as in Example 1.

[0060] (Comparative Example 1) A multilayer substrate sheet and a gravure printing layer were formed using the same method as in Example 1. A multilayer backer sheet consisting of a first backer sheet and a second backer sheet was prepared. As the first backer sheet, a sheet made of ABS resin that transmits visible light (thickness: 150 μm) was prepared. As the second backer sheet, a sheet was prepared in which a second polycarbonate resin layer (thickness: 200 μm) made of polycarbonate resin was placed between a third acrylic resin layer (thickness: 50 μm) made of acrylic resin and a fourth acrylic resin layer (thickness: 50 μm) made of acrylic resin. The first backer sheet was laminated on the second backer sheet so that the fourth acrylic resin layer of the second backer sheet was exposed to form a multilayer backer sheet. A multilayer substrate sheet was laminated on the multilayer backer sheet so that the adhesive layer of the gravure printing layer was in contact with the first backer sheet side of the multilayer backer sheet to create a light-transmitting decorative sheet.

[0061] (Comparative Example 2) A multilayer substrate sheet and a gravure printing layer were formed using the same method as in Example 1. A multilayer backer sheet consisting of a first backer sheet, a second backer sheet, and a third backer sheet was prepared. As the first backer sheet, a sheet made of ABS resin that transmits visible light (thickness: 100 μm) was prepared. As the second backer sheet, a sheet was prepared in which a second polycarbonate resin layer (thickness: 200 μm) made of polycarbonate resin was placed between a third acrylic resin layer (thickness: 50 μm) made of acrylic resin and a fourth acrylic resin layer (thickness: 50 μm) made of acrylic resin. As the third backer sheet, a sheet made of ABS resin that transmits visible light (thickness: 100 μm) was prepared. The first backer sheet, the second backer sheet, and the third backer sheet were laminated in this order to form a multilayer backer sheet. A light-transmitting decorative sheet was created by laminating a multilayer substrate sheet on top of a multilayer backer sheet so that the adhesive layer of the gravure printing layer was in contact with the first backer sheet side of the multilayer backer sheet.

[0062] (Comparative Example 3) A light-transmitting decorative sheet was prepared using a sheet with a different film thickness than that of Comparative Example 2 (Table 1), in the same manner as in Comparative Example 2.

[0063] [Table 1]

[0064] The light-transmitting decorative sheets obtained in the examples and comparative examples were subjected to the following tests to evaluate their moldability and the presence or absence of backer flow during injection molding. The results are shown in Table 2 below.

[0065] (Formability) Light-transmitting decorative sheets were heated to 140°C or 160°C and then shaped using a jig. Those that could be shaped were marked with ○, those that could be shaped to some extent were marked with △, and those that could not be shaped were marked with ×.

[0066] (Presence or absence of pinholes during excipient formation) The frequency of pinhole occurrence in the gravure printed layer was evaluated when light-transmitting decorative sheets were heated to 140°C or 160°C and shaped using a jig. ◎ indicated almost no pinholes, ○ indicated a few pinholes, △ indicated about 10 pinholes, and × indicated many pinholes. However, this evaluation was omitted for samples that could not be shaped during the shapeability evaluation.

[0067] (Backer flow during injection molding) Injection molding was performed using a light-transmitting decorative sheet, and the presence or absence of backer flow on the light-transmitting decorative sheet was visually checked. A circle (○) indicated no abnormalities, while a cross (×) indicated traces of backer flow.

[0068] (Trimming capability) The decorative sheets were trimmed using a trimming die. A circle (○) was used if the decorative sheet did not crack when trimmed at room temperature, and a cross (×) was used if it did crack.

[0069] [Table 2]

[0070] As can be seen from Table 2, no backer flow occurred during injection molding in Examples 1-4. Furthermore, the light-transmitting decorative sheets in Examples 2-4 showed excellent formability. In particular, the light-transmitting decorative sheets in Examples 3 and 4 could be formed at low temperatures (140°C), and the occurrence of pinholes during forming was suppressed. In contrast, backer flow occurred during injection molding in Comparative Examples 1-3. Moreover, forming was difficult even at high temperatures (160°C) in Comparative Examples 1-3.

[0071] In Examples 1 to 4, the multilayer backer sheet includes a second backer sheet 50 having a multilayer structure. In the multilayer backer sheet, when the side with the multilayer base sheet is placed facing upwards, a second polycarbonate resin layer 52 with excellent heat resistance is placed at the bottom of the multilayer backer sheet. This is thought to have suppressed the melting of the backer sheet due to thermal damage during injection molding. In Examples 2 to 4, the ratio of the thickness of the resin layer made of polycarbonate resin in the multilayer backer sheet to the thickness of the multilayer backer sheet is 19% or less, which is thought to have improved the shapeability of the light-transmitting decorative sheet. In Examples 3 and 4, the ratio of the thickness of the resin layer made of polycarbonate resin in the multilayer backer sheet to the thickness of the multilayer backer sheet is 13% or less. This increases the specific heat of the multilayer backer sheet, suppresses the temperature rise of the multilayer backer sheet during shaping, and is thought to have suppressed the occurrence of pinholes in the light-transmitting pattern layer and design layer of gravure printing.

[0072] In Examples 1 to 4, backer flow during injection molding was suppressed. The light-transmitting decorative sheet in Example 1 did not exhibit good formability, but it can be applied to molded products with shallow drawing processes that do not require a shaping process. The light-transmitting decorative sheets in Examples 2 to 4 exhibit good formability and can therefore be applied to molded products with deep drawing processes. [Explanation of symbols]

[0073] 10 Light-transmitting decorative sheet 20 Multilayer Substrate Sheets 21. First acrylic resin layer 22 First polycarbonate resin layer 23. Second Acrylic Resin Layer 24 Matte layer 25 Matte pattern layer 30 Gravure Printing Layers 31 Pattern Layers 32 Light-transmitting pattern layer 40. First backer seat 50 Second Backer Seat 51 Third Acrylic Resin Layer 52 Second polycarbonate resin layer 53. Fourth Acrylic Resin Layer 60 Multilayer Backer Sheets 71 Light-transmitting pattern layer 410 Heating drum (Example of a first contact heating element)

Claims

1. A multilayer substrate sheet that transmits visible light, having a first main surface and a second main surface, with a first polycarbonate resin layer made of polycarbonate resin disposed between a first acrylic resin layer and a second acrylic resin layer made of acrylic resin, Displaced on the first main surface side of the multilayer substrate sheet, the gravure printing layer has a pattern layer containing a gravure printed pattern and transmits visible light, A multilayer backer sheet is arranged on the opposite side of the multilayer substrate sheet of the gravure printing layer, The multilayer backer sheet or the multilayer substrate sheet comprises a light-transmitting pattern layer having a light-transmitting pattern that transmits visible light, The aforementioned multilayer backer sheet includes a first backer sheet and a second backer sheet. The first backer sheet is made of ABS resin or polypropylene resin and is a sheet that transmits visible light. The second backer sheet consists of a third acrylic resin layer made of acrylic resin and a second polycarbonate resin layer made of polycarbonate resin, and is positioned on the opposite side of the first backer sheet from the gravure printing layer, and is a sheet that transmits visible light. A light-transmitting decorative sheet in which, when the side on which the multilayer base sheet is arranged is considered upward, the second polycarbonate resin layer is arranged as the bottom layer of the multilayer backer sheet.

2. The decorative sheet according to claim 1, wherein the ratio of the thickness of the resin layer made of polycarbonate resin in the multilayer backer sheet to the thickness of the multilayer backer sheet is 9% or more and 19% or less.

3. The light-transmitting decorative sheet according to claim 1, wherein the thickness of the multilayer backer sheet is 400 μm or more and 600 μm or less.

4. The light-transmitting decorative sheet according to claim 1, wherein the total light transmittance of the first backer sheet is 30% or more and 60% or less.

5. A matte layer formed on the second main surface of the multilayer substrate sheet, The matte pattern layer formed on the aforementioned matte layer further comprises The matte layer comprises a first binder resin and a first matte material. The aforementioned matte pattern layer comprises a second binder resin and a second matte material. The light-transmitting decorative sheet according to claim 1, wherein the first binder resin and the second binder resin are two-component curable urethane resins which are cured products of a polyol and an isocyanate-based curing agent, and the ratio (NCO / OH) of isocyanate groups in the isocyanate-based curing agent to hydroxyl groups in the polyol is 1.1 to 2.

0.

6. A gravure printing process is performed on the first main surface of a multilayer substrate sheet having a first main surface and a second main surface, wherein a first polycarbonate resin layer made of polycarbonate resin is disposed between the first acrylic resin layer and the second acrylic resin layer made of acrylic resin, and the first main surface is transparent to visible light, and a gravure printing layer that transmits visible light is formed by gravure printing. A heat lamination step is performed in which a first backer sheet made of a visible light-transmitting ABS resin or polypropylene resin, a second backer sheet made of a visible light-transmitting acrylic resin layer and a second polycarbonate resin layer made of a polycarbonate resin, and a second backer sheet that transmits visible light is heat-laminated with the multilayer substrate sheet on which the gravure printing layer is formed. The process includes a light-transmitting pattern layer formation step, in which a light-transmitting pattern that transmits visible light is formed on the second backer sheet or the multilayer substrate sheet, A method for manufacturing a light-transmitting decorative sheet, wherein in the heat lamination step, the second polycarbonate resin layer of the second backer sheet is in contact with a first contact heating element, the first backer sheet is in contact with the second backer sheet, and the multilayer substrate sheet on which the gravure printing layer is formed is in contact with the first backer sheet, and the second backer sheet, the first backer sheet, and the multilayer substrate sheet are heat-laminated by heat supplied from the first contact heating element.

7. A shaping step for forming a light-transmitting decorative sheet according to any one of claims 1 to 5 into a three-dimensional shape, A trimming step is performed to trim and remove the unnecessary portion of the light-transmitting decorative sheet. The process of setting the light-transmitting decorative sheet into the mold, A method for manufacturing a decorated molded product, comprising an injection molding step of injecting a polycarbonate resin into the mold to form a resin molded body, and simultaneously fixing the surface of the resin molded body to the second polycarbonate resin layer of the light-transmitting decorative sheet.

8. A resin molded body and The resin molded body comprises a light-transmitting decorative sheet formed on the resin molded body, The aforementioned light-transmitting decorative sheet is Multilayer backer sheet and A multilayer base sheet formed on the multilayer backing sheet, A gravure printing layer formed on the multilayer backer sheet side of the multilayer substrate sheet, The multilayer backer sheet or the multilayer substrate sheet comprises a light-transmitting pattern layer having a light-transmitting pattern that transmits visible light, The aforementioned multilayer substrate sheet has an acrylic resin and a polycarbonate resin. The aforementioned multilayer backer sheet comprises a first backer sheet and a second backer sheet. The first backer sheet is made of ABS resin or polypropylene resin and is a sheet that transmits visible light. The second backer sheet consists of a third acrylic resin layer made of acrylic resin and a second polycarbonate resin layer made of polycarbonate resin. A decorative molded product in which the second polycarbonate resin layer is fixed to the resin molded body.

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