Decorative film, method for manufacturing a decorative film, and method for manufacturing a decorative molded product

Abstract

This invention provides a technology that can suppress the occurrence of air trapped during lamination in decorative films used in decorative molding. [Solution] The decorative film 1 for insert molding comprises a base film 20, an adhesive layer 30, and a backer film 40. The base film 20 has design layers 22 and 23 on at least one of its first surface 201 and second surface 202. The adhesive layer 30 is provided on the second surface 202 of the base film 20. The backer film 40 has a surface 401 that is adhered to the second surface 202 of the base film 20 via the adhesive layer 30. The surface 401 of the backer film 40 has fine irregularities over its entire surface. This suppresses the occurrence of air trapped between the surface 401 of the backer film 40 and the adhesive layer 30.

Description

Technical Field

[0001] The present invention relates to a molding die used for decorative molding and a method for manufacturing a decorative molded product.

Background Art

[0002] Conventionally, a decorative molding technique is known in which injection molding is performed with a decorative film inserted into a mold, so that decoration is applied to the surface of a molded product simultaneously with resin molding. A conventional decorative molding technique is described in, for example, Patent Document 1.

[0003] As described in Patent Document 1, the decorative film is formed by laminating a backer film that serves to maintain the shape of the base film onto a base film having a design layer (a multilayer film in Patent Document 1). Then, after the decorative film is three-dimensionally shaped, injection molding is performed with the decorative film inserted, whereby a resin molded product with the decorative film exposed on the surface can be obtained.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] During the production of such a decorative film, the base film and the backer film may be laminated by a dry lamination method. At this time, air bubbles may enter between the base film and the backer film, which is so-called air entrapment.

[0006] While air trapped in the mold often disappears during subsequent aging processes, not all air trapped air necessarily disappears, and some air may remain. In particular, when a decorative layer with irregularities is formed on the surface of the substrate film, air trapped air is more likely to occur along these irregularities, and the air is more likely to remain even after aging. If air remains, it can be heated during subsequent shaping and injection molding processes, causing it to expand and potentially adversely affecting the appearance and physical properties of the finished decorative molded product.

[0007] Therefore, the present invention aims to provide a technology that can suppress air trapped during lamination in decorative films used in decorative molding. [Means for solving the problem]

[0008] One aspect of the present invention is a decorative film for insert molding, comprising: a base film having a first surface and a second surface, with a design layer provided on at least one of the first surface and the second surface; an adhesive layer provided on the second surface of the base film; and a backer film having a front surface and a back surface, the front surface being bonded to the second surface of the base film via the adhesive layer, wherein the front surface of the backer film has fine irregularities over its entire surface.

[0009] A printed design layer formed by a printing process may be provided on the second surface of the substrate film.

[0010] The first surface of the substrate film may be provided with a textured design layer having irregularities.

[0011] When the uneven design layer is provided on the first surface, it is desirable that the surface roughness of the fine irregularities on the backer film is smaller than the surface roughness of the uneven design layer.

[0012] The surface roughness of the fine irregularities of the backer film is preferably such that the maximum height roughness Rz, measured by a stylus-type surface roughness measuring instrument in accordance with ISO 4288:1996, is 2.5 μm or more and 25.0 μm or less.

[0013] The glossiness of the fine irregularities of the backer film is preferably such that the specular gloss 60° gloss value, measured by a gloss meter in accordance with ISO 2813:2014, is 0.1 GU or more and 30 GU or less.

[0014] Another aspect of the present invention is a method for manufacturing a decorative film for insert molding, comprising: a) forming a design layer on at least one of the first and second surfaces of a substrate film having a first surface and a second surface; b) applying an adhesive to the second surface of the substrate film to form an adhesive layer; and c) bonding the surface of a backer film having a front surface and a back surface to the second surface of the substrate film via the adhesive layer, wherein the surface of the backer film has fine irregularities over its entire surface.

[0015] Another aspect of the present invention is a method for manufacturing a decorative molded article, comprising: A) a step of manufacturing a decorative film using the method for manufacturing a decorative film described above; and B) a step of filling a mold in which the decorative film is placed with molten resin and curing it to obtain a molded article comprising the decorative film and a resin part. [Effects of the Invention]

[0016] According to this disclosure, it is possible to suppress the occurrence of air trapped during lamination in decorative films used in decorative molding. [Brief explanation of the drawing]

[0017] [Figure 1] This is a perspective view of a molded product with a decorative film. [Figure 2] This is a cross-sectional view of the molded product. [Figure 3] This is a cross-sectional view showing the layer structure of the decorative film. [Figure 4] This is a flowchart showing the manufacturing procedure of a molded article. [Figure 5] This is a flowchart showing the manufacturing procedure of a decorative film. [Figure 6] This is a diagram showing the state of heating during shaping of the decorative film. [Figure 7] This is a diagram showing the state of forming during shaping of the decorative film. [Figure 8] This is a diagram showing the state of trimming after shaping the decorative film. [Figure 9] This is a diagram showing a state where the decorative film is inserted into a molding die. [Figure 10] This is a diagram showing the state of injection molding. [Figure 11] This is a diagram showing the state of releasing the molded article from the molding die. [Figure 12] This is an SEM observation image of the surface of the backer film. [Figure 13] This is a photographed image of the decorative film. [Mode for Carrying Out the Invention]

[0018] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. Note that in each drawing of the present disclosure, the dimensions of respective parts may be depicted in an exaggerated manner for ease of understanding.

[0019] <1. Decorative Molded Article> Figure 1 is a perspective view of a molded article 100 provided with a decorative film 1 according to one embodiment. Figure 2 is a cross-sectional view of the molded article 100. This molded article 100 is a resin product partially decorated with the decorative film 1. The decorative film 1 is a film for insert molding. The molded article 100 is used, for example, as an exterior panel of an automobile. However, the molded article 100 may also be used for automobile interiors or applications other than automobiles.

[0020] As shown in Figures 1 and 2, the molded product 100 has a decorative film 1 and a resin part 101. The decorative film 1 covers part or all of the surface of the resin part 101. During the manufacturing of the molded product 100, the decorative film 1 is inserted into the mold, and molten resin is injected into the mold. The resin part 101 is then molded by curing the resin in the mold. The decorative film 1 is fixed to the surface of the resin as the resin hardens in the mold. The detailed manufacturing procedure for the molded product 100 will be described later.

[0021] Figure 3 is a cross-sectional view showing the layer structure of the decorative film 1. As shown in Figure 3, the decorative film 1 has a base film 20, an adhesive layer 30, and a backer film 40.

[0022] The base film 20 is a layer for adding decorations such as patterns and colors to the molded product 100. The base film 20 has a base film body 21, a textured design layer 22, and a printed design layer 23. The base film 20 has a first surface 201 that is exposed to the outside of the resin part 101 and a second surface 202 that faces the resin part 101.

[0023] The first surface 201 of the base film 20 is provided with a textured design layer 22 having irregularities. The second surface 202 of the base film 20 is provided with a printed design layer 23 formed by a printing process. The base film 20 in this embodiment has both the textured design layer 22 and the printed design layer 23, but the present invention is not limited thereto. The base film 20 may have only one of the textured design layer 22 or the printed design layer 23.

[0024] The base film body 21 is formed from a transparent material. The textured design layer 22 is also formed from a transparent material. This allows the printed design layer 23, which is provided on the second surface 202 of the base film 20, to be visible from the first surface 201 side.

[0025] The base film body 21 can be made of, for example, PMMA (polymethyl methacrylate) or a mixed resin containing PVDF (polyvinylidene fluoride) and PMMA (polymethyl methacrylate). However, the base film body 21 may be made of other resins. The thickness of the base film body 21 is, for example, 30 μm to 150 μm.

[0026] The textured design layer 22 is formed by printing on the surface of the base film body 21 on the first surface 201 side. The textured design layer 22 is formed, for example, using gravure ink. Gravure ink contains 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 used in gravure inks include toluene, methyl ethyl ketone, ethyl acetate, and isopropyl alcohol.

[0027] The surface roughness of the uneven surface of the uneven design layer 22 is made small when the surface texture is a matte finish that has a visual effect but little tactile effect, and large when the surface texture is a highly uneven finish that makes the unevenness perceived both visually and tactilely. In the case of a matte finish, the surface roughness of the uneven surface of the uneven design layer 22 is such that the maximum height roughness Rz measured by a stylus-type surface roughness measuring instrument in accordance with ISO 4288:1996 is less than 20 μm. In the case of a highly uneven finish, the surface roughness of the uneven surface of the uneven design layer 22 is such that the maximum height roughness Rz measured by a stylus-type surface roughness measuring instrument in accordance with ISO 4288:1996 is 20 μm or more.

[0028] The printed design layer 23 is formed by printing on the second surface 202 side of the base film body 21. The printed design layer 23 is formed, for example, by gravure printing using gravure ink. However, the printed design layer 23 may be formed by printing methods other than gravure printing. Furthermore, the printed design layer 23 may have a primer layer provided on top of the design layer formed by gravure printing to protect the design layer. In that case, the primer layer is transparent and is formed from, for example, vinyl chloride vinyl acetate copolymer resin, acrylic resin, polyester resin, or polyurethane resin.

[0029] The adhesive layer 30 is a layer of adhesive interposed between the base film 20 and the backer film 40. The adhesive layer 30 adheres the second surface 202 of the base film 20 to the surface 401 of the backer film 40, which will be described later. The adhesive constituting the adhesive layer 30 can be, for example, a two-component curing urethane resin, a two-component curing polyester-urethane resin, or a two-component curing ester resin. These adhesives are suitable for dry lamination at low temperatures of 100°C or below.

[0030] The backer film 40 is a resin-based base film. The backer film 40 plays a role in maintaining the shape of the decorative film 1. The thickness of the backer film 40 is, for example, 150 μm to 250 μm. For the material of the backer film 40, for example, a polycarbonate-based resin is used. However, polyester-based resins, vinyl chloride-based resins, acrylic-based resins, polypropylene-based resins, polyethylene-based resins, polyurethane-based resins, polystyrene-based resins, acetate-based resins, polyamide-based resins, etc. may also be used as the material of the backer film 40. Furthermore, the backer film 40 may be a mixture of two or more of these materials.

[0031] The backer film 40 has a front surface 401 and a back surface 402. The front surface 401 is bonded to the second surface 202 of the base film 20 via an adhesive layer 30. The back surface 402 is fixed to the resin part 101 by insert molding. The front surface 401 of the backer film 40 has fine irregularities over its entire surface. As a result, the texture of the front surface 401 is a matte finish.

[0032] <2. Method for manufacturing decorative molded products> Next, we will explain the manufacturing method for the molded product 100 having the decorative film 1 described above. Figure 4 is a flowchart showing the manufacturing procedure for the molded product 100. Figure 5 is a flowchart showing the manufacturing procedure for the decorative film 1. Figures 6 to 11 show the process of manufacturing the molded product 100.

[0033] As shown in Figure 4, when manufacturing the molded product 100, the first step is to manufacture the decorative film 1 (step S1). Specifically, as shown in Figure 3, first, a printed design layer 23 is formed on the second surface of the base film body 21 by gravure printing (step S101). Subsequently, a textured design layer 22 is formed on the first surface of the base film body 21 by gravure printing (step S102). This results in a base film 20 having a textured design layer 22 on the first surface 201 and a printed design layer 23 on the second surface 202.

[0034] Note that the order of steps S101 and S102 may be reversed. Also, if the base film 20 has only one of the textured design layer 22 and the printed design layer 23, one of steps S101 and S102 may be omitted.

[0035] Next, adhesive is applied to the second surface 202 of the base film 20 (step S103). This laminates the adhesive layer 30 onto the second surface 202 of the base film 20.

[0036] Subsequently, the substrate film 20 having the adhesive layer 30 and the backer film 40 are laminated at a low temperature of 100°C or less using a dry lamination method (step S104). This produces the decorative film 1.

[0037] In step S1, the base film body 21 and the backer film 40 are long, strip-shaped substrates. Therefore, the gravure printing, adhesive application, and lamination in steps S101 to S104 are performed using a roll-to-roll method. Upon completion of step S104, the long, strip-shaped decorative film 1 is wound around the core in a roll shape.

[0038] Finally, the decorative film 1 is cut into short sheets of a predetermined length (step S105). In this way, the decorative film 1 is manufactured. At this time, the cutting length of the decorative film 1 is set to a length suitable for the subsequent shaping process (step S2).

[0039] After the decorative film 1 is manufactured in step S1, the planar decorative film 1 is then shaped into a three-dimensional shape (step S2). In step S2, first, the decorative film 1 is heated by a heater 90, as shown in Figure 5. This softens the decorative film 1. Then, as shown in Figure 7, the decorative film 1 is shaped into a predetermined shape by vacuum forming or pressure forming. After that, as shown in Figure 8, the unnecessary portion of the outer periphery of the shaped decorative film 1 is trimmed by a cutter 80.

[0040] Next, the formed decorative film 1 is inserted into the molding die 70 (step S3). As shown in Figure 9, the molding die 70 has a first die 71 and a second die 72. The decorative film 1 is positioned along the concave surface that forms the cavity 73 of the first die 71. Then, as shown in Figure 9, the first die 71 and the second die 72 are clamped together. This forms a cavity 73 between the first die 71 and the second die 72, and the decorative film 1 is inserted into this cavity 73.

[0041] In this state, injection molding is performed using the molding die 70 (step S4). Specifically, as shown in Figure 10, molten resin injected from the gate 74 provided in the second mold 72 fills the cavity 73. Then, the resin part 101 is formed by curing the molten resin in the molding die 70. The decorative film 1 is fixed to the surface of the resin when the resin hardens in the mold.

[0042] Subsequently, as shown in Figure 11, the first mold 71 and the second mold 72 are opened, and the molded product 100 is released from the molding die 70. This yields a molded product 100 equipped with a resin part 101 and a decorative film 1.

[0043] <3. Regarding air bubbles> In the procedure described above, when laminating the base film 20 and the backer film 40 in step S104, air trapped (residual air bubbles) may occur between the base film 20 and the backer film 40, that is, between the adhesive layer 30 and the backer film 40.

[0044] In particular, if the base film 20 has an uneven design layer 22, or if some unevenness occurs depending on the type of pattern printed in the printed design layer 23, air is more likely to get trapped between the adhesive layer 30 and the backer film 40.

[0045] While air trapped in the mold often disappears during subsequent aging processes, not all air trapped in the mold disappears, and some air may remain. If air remains, it may be heated during the subsequent shaping process (step S2) and injection molding process (step S4), causing the air to expand and potentially adversely affecting the appearance and physical properties of the finished molded product 100.

[0046] As described above, in this decorative film 1, the surface 401 of the backer film 40 has fine irregularities over its entire surface. In other words, the surface 401 has a so-called matte finish or non-glossy finish.

[0047] Figure 12 shows images obtained by observing the surface 401 of the backer film 40 with an SEM (scanning electron microscope). The upper panel of Figure 12 shows the observation image at an acceleration voltage of 20kV and a magnification of 250x, and the lower panel shows the observation image at an acceleration voltage of 20kV and a magnification of 750x.

[0048] The surface roughness of the fine irregularities of the backer film 40 is less than the surface roughness of the textured design layer 22. The surface roughness of the fine irregularities of the backer film 40 has a maximum height roughness Rz of 2.5 μm or more and 25.0 μm or less, as measured by a stylus-type surface roughness measuring instrument in accordance with ISO 4288:1996. In addition, the glossiness of the fine irregularities of the backer film 40 has a specular gloss 60° gloss value of 0.1 GU or more and 30 GU or less, as measured by a gloss meter in accordance with ISO 2813:2014.

[0049] In this way, the surface 401 of the backer film 40 has fine irregularities, which suppresses the occurrence of air trapped during the lamination process (step S104).

[0050] Figure 13 shows an example of an image of the decorative film 1 taken from the back surface 402 side of the backer film 40. The upper part of Figure 13 shows an image of the decorative film 1 when the surface 401 of the backer film 40 has fine irregularities. The lower part of Figure 13 shows an image of the decorative film 1 when the surface 401 of the backer film 40 is smooth.

[0051] In the upper image of the decorative film 1 in Figure 13, a fine linear pattern can be seen extending from the lower left to slightly to the upper right. This linear pattern is due to fine linear irregularities on the base film 20. The several white, granular objects visible are air bubbles B. On the other hand, in the lower image of the decorative film 1 in Figure 13, numerous white, granular air bubbles can be seen along the fine linear pattern extending from the lower left to slightly to the upper right. From this, it can be seen that air is less likely to be trapped when the surface 401 of the backer film 40 has fine irregularities.

[0052] If the surface 401 of the backer film 40 is smooth, when the surface 401 comes into contact with the adhesive layer 30 during lamination, the contact area immediately adheres. Therefore, as the substrate film 20 and the backer film 40 gradually come into contact from the upstream side, if an air bubble remains between the adhesive layer 30 and the backer film 40, the area around the air bubble will adhere before the air bubble can escape to the downstream side. However, some of the air bubble will move outwards due to the lamination pressure, pulling the adhesive area apart again, and disappear. However, some of the remaining air bubble will not escape and will remain. This is why air is trapped in the lamination.

[0053] On the other hand, if the surface 401 of the backer film 40 has fine irregularities, during lamination, first the convex portions of the fine irregularities on the surface 401 come into contact with the adhesive layer 30, and then the entire surface 401, including the concave portions, adheres to the adhesive layer 30. At this time, as the substrate film 20 and the backer film 40 gradually come into contact from the upstream side, if air bubbles are likely to remain between the adhesive layer 30 and the backer film 40, the area around the air bubbles (especially the downstream side) will have contact with the adhesive layer 30 and adhesion will begin, but the concave portions will not yet be completely bonded, resulting in a weak adhesion state. When the air bubbles are pushed from the upstream side to the downstream side by the lamination pressure, the substrate can move downstream from areas where the concave portions are continuous, or it can move while pulling away the weakly bonded areas consisting only of convex portions. For this reason, when the surface 401 has fine irregularities, air bubbles are less likely to remain and air trapping can be suppressed compared to when the surface 401 is smooth.

[0054] <4. Variation> Although one embodiment has been described above, this disclosure is not limited to the above embodiment.

[0055] In the above embodiment, the decorative film 1 was shaped. However, the decorative film 1 may be used without being shaped.

[0056] Furthermore, in the above embodiment, the decorative film 1 covered only a portion of the surface of the molded product 100. However, the decorative film 1 may cover the entire surface of the molded product 100.

[0057] Furthermore, the elements appearing in the above embodiments and modifications may be combined or partially deleted to the extent that no inconsistencies arise. In addition, known elements may be added to the configurations appearing in the above embodiments and modifications as appropriate. [Explanation of symbols]

[0058] 1: Decorative film 20: Substrate film 21: Base film body 22: Textured design layer 23: Printed design layer 30: Adhesive layer 40: Backer film 100: Molded product 101: Resin part 201: 1st page 202: 2nd side 401 :Surface 402: Back side

Claims

1. A decorative film for insert molding, A substrate film having a first surface and a second surface, wherein a design layer is provided on at least one of the first surface and the second surface, An adhesive layer provided on the second surface of the substrate film, A backer film having a front surface and a back surface, wherein the front surface is bonded to the second surface of the substrate film via the adhesive layer, Equipped with, The surface of the backer film is a decorative film having fine irregularities over its entire surface.

2. The decorative film according to claim 1, wherein a printed design layer formed by a printing process is provided on the second surface of the substrate film.

3. The decorative film according to claim 1, wherein the first surface of the substrate film is provided with a textured design layer having irregularities.

4. The decorative film according to claim 3, wherein the surface roughness of the fine irregularities of the backer film is smaller than the surface roughness of the irregular design layer.

5. The decorative film according to any one of claims 1 to 3, wherein the surface roughness of the fine irregularities of the backer film is such that the maximum height roughness Rz, measured by a stylus-type surface roughness measuring instrument in accordance with ISO 4288:1996, is 2.5 μm or more and 25.0 μm or less.

6. The decorative film according to any one of claims 1 to 3, wherein the glossiness of the fine irregularities of the backer film is such that the specular gloss 60° gloss value measured by a gloss meter in accordance with ISO 2813:2014 is 0.1 GU or more and 30 GU or less.

7. A method for manufacturing decorative films for insert molding, a) A step of forming a design layer on at least one of the first surface and the second surface of a substrate film having a first surface and a second surface, b) A step of applying adhesive to the two surfaces of the substrate film to form an adhesive layer, c) A step of bonding the front surface of a backer film having a front surface and a back surface to the second surface of the substrate film via the adhesive layer, It has, A method for manufacturing a decorative film, wherein the surface of the backer film has fine irregularities over its entire surface.

8. A method for manufacturing a decorated molded product, A) A step of manufacturing the decorative film using the method for manufacturing the decorative film described in claim 7, B) A step of obtaining a molded product comprising the decorative film and the resin part by filling a mold in which the decorative film is placed inside with molten resin and curing it, A method for manufacturing a decorative molded product having the following characteristics.

Images