Film-bonded resin plate and method for manufacturing film-bonded resin plate

Abstract

A film-bonded resin plate (10) includes a laminate (12) having: a resin plate (11) made of polycarbonate; a functional film (31); and an adhesive (21) that forms a layer interposed between the resin plate (11) and the functional film (31), and that bonds the functional film (31) to a first main surface (11a) of the resin plate (11). The adhesive (21) has an adhesive force higher than the saturated water vapor pressure at a first upper limit temperature, which is the upper limit of a heat-resistance temperature required in the use environment of the film-bonded resin plate (10).

Description

Film-laminated resin plate and method for manufacturing film-laminated resin plate

[0001] The present invention relates to a film-laminated resin plate and a method for manufacturing a film-laminated resin plate.

[0002] A film-laminated resin plate is manufactured, for example, by laminating a functional film having functions such as heat insulation and gas barrier properties to the surface of a resin plate. Resin plates made of, for example, polycarbonate are known. The functional film is laminated to one side of the resin plate with an adhesive layer. A method for manufacturing a film-laminated resin plate is disclosed, for example, in Patent Document 1. In the method disclosed in Patent Document 1, an adhesive is first interposed between the resin plate and the functional film to produce a laminate in which the resin plate, adhesive layer, and functional film are laminated in this order. This laminate is then pressed to produce a laminate in which the resin plate and the functional film are laminated together with the adhesive.

[0003] Japanese Patent Application Laid-Open No. 2013-4902

[0004] Depending on the type of adhesive used in the film-laminated resin plate, the adhesive strength between the resin plate and the functional film may decrease if the film-laminated resin plate is used in a high-temperature environment. This decrease in adhesive strength is undesirable because it may cause air bubbles to form between the resin plate and the functional film.

[0005] The film-laminated resin plate for solving the above problem is a film-laminated resin plate including a laminate having a resin plate made of polycarbonate, a functional film, and an adhesive that forms a layer interposed between the resin plate and the functional film and bonds the functional film to one side of the resin plate, and is characterized in that the adhesive has an adhesive strength higher than the saturated water vapor pressure at a first upper limit temperature, which is the upper limit of the heat resistance temperature required in the usage environment of the film-laminated resin plate.

[0006] A method for manufacturing a film-laminated resin plate to solve the above problem is a method for manufacturing a film-laminated resin plate including a laminate having a resin plate made of polycarbonate, a functional film, and an adhesive that forms a layer interposed between the resin plate and the functional film and bonds the functional film to one side of the resin plate, and is characterized in that the adhesive has an adhesive strength higher than the saturated water vapor pressure at a first upper limit temperature, which is the upper limit of the heat resistance temperature required in the usage environment of the film-laminated resin plate.

[0007] According to the above configuration and method, even when the temperature of the film-laminated resin plate reaches the first upper limit temperature, which is the upper limit of the heat resistance temperature required in the usage environment of the film-laminated resin plate, the moisture contained in the resin plate and the adhesive is unlikely to evaporate, and therefore, the generation of bubbles between the resin plate and the functional film due to the evaporation of the moisture contained in the resin plate and the adhesive can be suppressed.

[0008] The method for manufacturing a film-laminated resin plate may include a bending step in which the laminate is heated and bent, and the adhesive may have an adhesive strength higher than the saturated water vapor pressure at a second upper limit temperature, which is the upper limit temperature of the laminate in the bending step and is higher than the first upper limit temperature.

[0009] According to the above method, even when the temperature of the film-laminated resin plate reaches the second upper limit temperature, which is the upper limit of the temperature of the laminate during the bending process, the moisture contained in the resin plate and the adhesive is unlikely to evaporate. Therefore, even when the film-laminated resin plate is bent, the generation of bubbles between the resin plate and the functional film due to the evaporation of the moisture contained in the resin plate and the adhesive can be suppressed.

[0010] According to this invention, it is possible to suppress the generation of bubbles between the resin plate and the functional film, which would otherwise occur due to evaporation of water contained in the resin plate or adhesive.

[0011] Fig. 1 is a cross-sectional view showing a film-laminated resin plate. Fig. 2 is a schematic side view for explaining a peel test. Fig. 3 is a schematic top view for explaining a peel test. Fig. 4 is a table showing the adhesive strength of an adhesive and the results of an air bubble test. Fig. 5 is a graph showing the relationship between temperature and saturated water vapor pressure.

[0012] Hereinafter, an embodiment embodying a film-laminated resin plate and a method for manufacturing the film-laminated resin plate will be described with reference to the drawings. The film-laminated resin plate is useful for various applications, such as automobile parts, electronic devices, office automation equipment, machine parts, agricultural materials, fishing materials, transport containers, packaging containers, play equipment, and miscellaneous goods. The film-laminated resin plate in this embodiment is exemplified as a vehicle window member used as an automobile part. Specific examples of vehicle window members include back door windows, sunroofs, and roof panels. The film-laminated resin plate also has a three-dimensional shape.

[0013] 1 , a film-laminated resin plate 10 includes a laminate 12 having a resin plate 11, a functional film 31, and an adhesive 21. The adhesive 21 forms a layer interposed between the resin plate 11 and the functional film 31.

[0014] <Resin Plate> The resin plate 11 is made of polycarbonate. The resin plate 11 is manufactured by, for example, extrusion molding or injection molding. The resin plate 11 has a first main surface 11a and a second main surface 11b that are opposite to each other in the plate thickness direction. Of the first main surface 11a and the second main surface 11b, the first main surface 11a is the surface that faces the exterior side of the vehicle window member in which the film-laminated resin plate 10 is used, and the second main surface 11b is the surface that faces the interior side of the vehicle window member.

[0015] <Functional Film> Examples of the types of functional film 31 include a heat ray reflective film, a barrier film, a light control film, a Low-E film, a conductive film-forming film, a screen film, a perovskite solar cell, etc. In short, the type of functional film 31 is not limited as long as the functional film 31 imparts a function to the resin plate 11 by being attached to the resin plate 11.

[0016] <Adhesive> The adhesive 21 bonds the functional film 31 to the first main surface 11a, which is one surface of the resin plate 11. In other words, the functional film 31 is bonded to the first main surface 11a of the resin plate 11 by the adhesive 21.

[0017] The adhesive 21 is made of, for example, a thermosetting resin. For example, the adhesive 21 is primarily composed of an epoxy resin. The adhesive 21 may be composed solely of an epoxy resin, or may be primarily composed of a resin other than an epoxy resin. The epoxy resin may be a one-component type or a two-component type. Examples of resins other than epoxy resin include polyurethane resin, acrylic resin, and polyester resin. The thermosetting resin adhesive 21 softens when heated and then hardens through a crosslinking reaction. Such adhesive 21 is applied in advance to the entire surface of one side of the functional film 31 before being bonded to the resin plate 11. Therefore, the functional film 31 before being bonded to the resin plate 11 integrally contains the adhesive 21. The thermosetting resin adhesive 21 does not generate adhesive force at room temperature but can deform integrally with the functional film 31. Furthermore, when the thermosetting resin adhesive 21 is heated to a predetermined temperature, the adhesive 21 begins to generate adhesive force. As the adhesive 21 is further heated, the cross-linking reaction progresses, and the adhesive 21 strongly bonds the objects together.

[0018] Although not shown, a hard coat or a decorative layer may be provided on at least one surface of the laminate 12 in the stacking direction. Examples of the decorative layer include a decorative layer with good adhesion to the resin, such as black printing. When only one of the hard coat and the decorative layer is provided on the laminate 12, the one surface of the laminate 12 in the stacking direction corresponds to the second main surface 11b of the resin plate 11. The other surface of the laminate 12 in the stacking direction corresponds to the surface of both sides of the functional film 31 on which the adhesive 21 is not provided. When both a hard coat and a decorative layer are provided on the laminate 12, for example, the decorative layer may be provided on the hard coat. In this case, for example, the one surface of the laminate 12 in the stacking direction corresponds to the surface of the hard coat provided on the second main surface 11b of the resin plate 11. The other surface of the laminate 12 in the stacking direction corresponds to the surface of the hard coat provided on the functional film 31.

[0019] <Adhesive Strength of Adhesive> The adhesive 21 has an adhesive strength higher than the saturated water vapor pressure at a first upper limit temperature T1. The first upper limit temperature T1 is the upper limit of the heat resistance temperature required in the usage environment of the film-laminated resin plate 10. In this embodiment, it is the upper limit of the heat resistance temperature required in the operating environment of the vehicle in which the film-laminated resin plate 10 is used. The first upper limit temperature T1 is, for example, 120°C.

[0020] Furthermore, the adhesive 21 in this embodiment has an adhesive strength higher than the saturated water vapor pressure at a second upper limit temperature T2 that is higher than the first upper limit temperature T1. The second upper limit temperature T2 is the upper limit of the temperature of the laminate 12 in a bending process (described later) that is performed when manufacturing the film-laminated resin plate 10. The second upper limit temperature T2 is, for example, 150°C.

[0021] <Method for manufacturing film-laminated resin plate> The method for manufacturing the film-laminated resin plate 10 is a method for manufacturing the laminate 12 by laminating a functional film 31 having an adhesive 21 to one side of the resin plate 11, that is, a first main surface 11a. Then, the thermosetting adhesive 21 of the laminate 12 is cured, thereby completing the film-laminated resin plate 10.

[0022] The manufacturing method of the film-laminated resin plate 10 in this embodiment includes a lamination step. In the lamination step, for example, first, at least one of the resin plate 11 and the functional film 31 integrated with the adhesive 21 is heated. While this heating is being performed, the functional film 31 is laminated to the first main surface 11a of the resin plate 11. As a result, in the lamination step, a laminate 12 is manufactured in which the adhesive 21 is interposed between the resin plate 11 and the functional film 31. Note that the manufacturing method of the film-laminated resin plate 10 does not have to include the lamination step. In this case, the film-laminated resin plate 10 is manufactured using an already manufactured laminate 12.

[0023] The manufacturing method of the film-laminated resin plate 10 includes a bending process. The bending process is a process of bending the laminate 12 while heating it. Specifically, in the bending process, the laminate 12 is heated and deformed so that the laminate 12 is curved in the plate thickness direction of the resin plate 11. At this time, the laminate 12 may be supported by support members (not shown) from both sides in the stacking direction. These support members may apply pressure to the laminate 12 in the stacking direction. In the bending process, the temperature of the laminate 12 is set to a temperature at which the resin plate 11, which is made of polycarbonate, can be deformed. This temperature is set to, for example, 120°C or higher and 150°C or lower.

[0024] In the bending process, the laminate 12 is bent while being heated, so that the laminate 12 is bent with the functional film 31 bonded to the first main surface 11a of the resin plate 11. When the bending process is completed, a curved film-laminated resin plate 10 is manufactured. Thereafter, the thermosetting adhesive 21 of the laminate 12 is cured, thereby completing the curved film-laminated resin plate 10. This film-laminated resin plate 10 is used as a window member for a vehicle.

[0025] <Comparison with Comparative Examples> The inventors conducted a peel test on a number of thermosetting test adhesives. This test was conducted using five types of thermosetting adhesives, namely, Adhesive A, Adhesive B, Adhesive C, Adhesive D, and Adhesive E. Adhesive A and Adhesive B are thermosetting adhesives made from epoxy resin. Adhesive C is a thermosetting adhesive made from polyester resin. Adhesive D and Adhesive E are thermosetting adhesives made from acrylic resin.

[0026] 2 and 3 , the peel test was performed using a test laminate 112 including a test resin plate 111, a test functional film 131, and a test adhesive 121. The test adhesive 121 is a layer interposed between the test resin plate 111 and the test functional film 131. The test resin plate 111 has a test first main surface 111a as one side and a test second main surface 111b as the other side. The test adhesive 121 bonds the test functional film 131 to the test first main surface 111a, which is one side of the test resin plate 111.

[0027] In the test laminate 112 used in the peel test, the test resin plate 111 was the same as the above-mentioned resin plate 11 except for its shape. The test functional film 131 was the same as the above-mentioned functional film 31 except for its shape. Then, a peel test was performed on each test laminate 112 using adhesive A, adhesive B, adhesive C, adhesive D, and adhesive E as the test adhesive 121.

[0028] In the test laminate 112 used in the peel test, the test resin plate 111, the test functional film 131, and the test adhesive 121 each have a rectangular flat plate shape. The test resin plate 111, the test functional film 131, and the test adhesive 121 all have the same width W. Note that the width W is, for example, the dimension in the direction in which the short edge of each of the test resin plate 111, the test functional film 131, and the test adhesive 121 extends. For example, the width W is 10 mm.

[0029] In the peel test, the test resin plate 111 and the test functional film 131 were first pulled in opposite directions along the direction of their long edges, as shown by the white arrows in Figure 2. The load pulling the test functional film 131 was then gradually increased, and the load acting on the test functional film 131 was measured when the test functional film 131 peeled off the test resin plate 111. The magnitude of the load thus measured was taken as the adhesive strength of each of adhesives A, B, C, D, and E. Note that this adhesive strength is the load (N) when the width W is 10 mm, and therefore the adhesive strength is expressed in units of "N / 10 mm."

[0030] 4 and 5, the peel test was carried out under the condition that the test laminate 112 was at 120° C. The results showed that under the condition that the test laminate 112 was at 120° C., adhesives A and B made of epoxy resins had greater adhesive strength than adhesive C made of polyester resin and adhesives D and E made of acrylic resin.

[0031] Additionally, in conjunction with the peel test conducted under conditions where the test laminate 112 was at 120°C, a bubble test was conducted to check whether bubbles were generated in the test adhesive 121. No bubbles were observed in the test adhesive 121 using adhesive A and adhesive B, but bubbles were observed in the test adhesive 121 using adhesive C, adhesive D, and adhesive E. From the results of this bubble test, it can be determined that adhesives C, adhesive D, and adhesive E, which are made of resins other than epoxy resins, showed an earlier decrease in adhesive strength, causing bubbles to be generated, compared to adhesives A and B, which are made of epoxy resins.

[0032] Here, assuming that the test adhesive 121 is adhered to the test resin plate 111 under conditions of a width W of 10 mm and a length of 1 mm, for example, the saturated water vapor pressure of the test adhesive 121 with an adhesive strength of 5 N / 10 mm can be estimated to be 0.5 MPa. Therefore, from the test results shown in Figure 4, when the test laminate 112 is at 120°C, the saturated water vapor pressure of adhesive A, which had an adhesive strength of 3.14 N / 10 mm, can be estimated to be 0.314 MPa. When the test laminate 112 is at 120°C, the saturated water vapor pressure of adhesive B, which had an adhesive strength of 2.89 N / 10 mm, can be estimated to be 0.289 MPa.

[0033] The saturated water vapor pressure can be calculated as e(T) using the Tetens equation, Equation 1 below. A graph of the saturated water vapor pressure calculated using Equation 1 is shown in FIG.

[0034]

[0035] 5, if the temperature is lower than the saturated water vapor pressure, the water contained in the test resin plate 111 and the test adhesive 121 will evaporate, which may cause air bubbles to form between the test resin plate 111 and the test functional film 131. From FIG. 5, it can be seen that the saturated water vapor pressure at a temperature of 120°C is 0.2 MPa, and the saturated water vapor pressure at a temperature of 150°C is 0.5 MPa.

[0036] As described above, when the test laminate 112 was heated to 120°C, the saturated water vapor pressure of adhesive A was estimated to be 0.314 MPa, and the saturated water vapor pressure of adhesive B was estimated to be 0.289 MPa. Therefore, both adhesive A and adhesive B exceed the saturated water vapor pressure of 0.2 MPa at a temperature of 120°C. Therefore, it can be determined that air bubbles are unlikely to form between the test resin plate 111 and the test functional film 131 in the test laminate 112 using either adhesive A or adhesive B when the test laminate 112 is heated to 120°C. Therefore, the adhesive 21 has an adhesive strength higher than the saturated water vapor pressure at the first upper limit temperature T1, which is the upper limit of the heat resistance temperature required in the usage environment of the film-laminated resin plate 10.

[0037] [Operations and Effects of the Embodiment] The operations and effects of the present embodiment will be described. (1) The film-laminated resin plate 10 includes a laminate 12 having a resin plate 11 made of polycarbonate, a functional film 31, and an adhesive 21. The adhesive 21 forms a layer interposed between the resin plate 11 and the functional film 31, and bonds the functional film 31 to a first main surface 11a, which is one side of the resin plate 11. The adhesive 21 has an adhesive strength higher than the saturated water vapor pressure at a first upper limit temperature T1, which is the upper limit of the heat resistance temperature required in the usage environment of the film-laminated resin plate 10. Therefore, even if the temperature of the film-laminated resin plate 10 reaches the first upper limit temperature T1, which is the upper limit of the heat resistance temperature required in the usage environment of the film-laminated resin plate 10, moisture contained in the resin plate 11 and the adhesive 21 is unlikely to evaporate. Therefore, the generation of air bubbles between the resin plate 11 and the functional film 31 due to evaporation of moisture contained in the resin plate 11 and the adhesive 21 can be suppressed.

[0038] (2) The manufacturing method of the film-laminated resin plate 10 includes a bending step in which the laminate 12 is heated and bent. The adhesive 21 has an adhesive strength higher than the saturated water vapor pressure at a second upper limit temperature T2, which is the upper limit temperature of the laminate 12 during the bending step and is higher than the first upper limit temperature T1. Therefore, even when the temperature of the film-laminated resin plate 10 reaches the second upper limit temperature T2, which is the upper limit temperature of the laminate 12 during the bending step, the moisture contained in the resin plate 11 and the adhesive 21 is unlikely to evaporate. Therefore, even when the film-laminated resin plate 10 is bent, the generation of air bubbles between the resin plate 11 and the functional film 31 due to the evaporation of the moisture contained in the resin plate 11 and the adhesive 21 can be suppressed.

[0039] [Modifications] The embodiment can be modified as follows: The embodiment and the following modifications can be combined with each other within the scope of technical compatibility.

[0040] The second upper limit temperature T2 may be lower than 150°C or higher than 150°C. In other words, the second upper limit temperature T2 may be any temperature higher than the first upper limit temperature. The manufacturing method for the film-laminated resin plate 10 does not have to include the bending step. In this case, the film-laminated resin plate 10 may be, for example, flat and not curved.

[0041] When the manufacturing method for the film-laminated resin plate 10 does not include a bending step as in the above modified example, the adhesive 21 does not need to have an adhesive strength higher than the saturated water vapor pressure at the second upper limit temperature T2. In this case, the adhesive 21 only needs to have an adhesive strength higher than the saturated water vapor pressure at the first upper limit temperature T1.

[0042] Of the first main surface 11a and the second main surface 11b, the first main surface 11a may be the surface facing the inside of the vehicle in the vehicle window member in which the film-laminated resin plate 10 is used, and the second main surface 11b may be the surface facing the outside of the vehicle in the vehicle window member.

[0043] T1: First upper limit temperature T2: Second upper limit temperature 10: Film-laminated resin plate 11: Resin plate 11a: First main surface (as one side) 12: Laminate 21: Adhesive 31: Functional film

Claims

1. A film-laminated resin plate including a laminate having: a resin plate made of polycarbonate; a functional film; and an adhesive that forms a layer between the resin plate and the functional film and bonds the functional film to one side of the resin plate, wherein the adhesive has an adhesive strength higher than the saturated water vapor pressure at a first upper limit temperature, which is the upper limit of the heat resistance temperature required in the usage environment of the film-laminated resin plate.

2. A method for manufacturing a film-laminated resin plate including a laminate having a resin plate made of polycarbonate, a functional film, and an adhesive that forms a layer between the resin plate and the functional film and bonds the functional film to one side of the resin plate, wherein the adhesive has an adhesive strength higher than the saturated water vapor pressure at a first upper limit temperature, which is the upper limit of the heat resistance temperature required in the usage environment of the film-laminated resin plate.

3. A method for manufacturing a film-laminated resin plate as described in claim 2, further comprising a bending process of heating and bending the laminate, wherein the adhesive has an adhesive strength higher than the saturated water vapor pressure at a second upper limit temperature, which is the upper limit temperature of the laminate in the bending process and is higher than the first upper limit temperature.

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