Production method

Abstract

To provide a method for producing a resin molded product that does not require a heating step after molding.SOLUTION: A production method includes: a coating step of coating a resin containing a UV curable resin and a thermosetting resin on a thermoplastic resin sheet to form a resin layer; a heating step of heating the resin layer so that the thermosetting resin becomes a cured state; a first irradiation step of irradiating the resin layer with UV so that the UV curable resin becomes a semi-cured state; a molding step of molding the thermoplastic resin sheet on which the resin layer is formed; and a second irradiation step of irradiating the resin layer with UV so that the UV curable resin becomes a cured state, after the molding step. The first irradiation step and the heating step are performed until molding at the molding step is completed.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a method of manufacture. [Background technology]

[0002] Conventionally, there is a manufacturing method for a product in which a base material is coated, in which a plate-shaped base material is coated and then the base material is shaped. In this manufacturing method, pressure is applied to the coated surface in a process after coating, and marks may remain on the coated surface. Therefore, there is a technique for suppressing marks formed when pressure is applied. For example, Patent Document 1 discloses a precoated steel sheet in which a clear coating film for absorbing pressure is provided on the non-coated surface of the steel sheet, which is the base material. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 05-185030 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the case of a manufacturing method in which a substrate is painted and then molded, there is another problem that molding is difficult in the molding process because the substrate already has a painted surface formed on it. Note that these problems are common not only when the substrate is a steel plate but also when the substrate is a resin sheet. [Means for solving the problem]

[0005] The present disclosure can be realized in the following forms.

[0006] (1) According to one embodiment of the present disclosure, a method for manufacturing a resin molded product is provided. This manufacturing method includes a coating step of coating a thermoplastic resin sheet with a resin containing a UV curable resin and a thermosetting resin to form a resin layer, a heating step of heating the resin layer so that the thermosetting resin is in a cured state, a first irradiation step of irradiating the resin layer with UV light so that the UV curable resin is in a semi-cured state, a molding step of molding the thermoplastic resin sheet on which the resin layer is formed, and a second irradiation step of irradiating the resin layer with UV light after the molding step so that the UV curable resin is in a cured state, and the first irradiation step and the heating step are performed until the molding step is completed. According to this embodiment, the resin layer contains a UV curable resin and a thermosetting resin, and the heating step and the first irradiation step are performed to impart extensibility and a desired hardness to the resin layer. Therefore, in the molding step, the thermoplastic resin sheet on which the resin layer is formed can be appropriately molded, and in the steps after the molding step, even if pressure is applied to the resin layer, it is difficult to leave a mark. (2) In the manufacturing method of the above aspect, an integrated amount of UV light in the first irradiation step may be smaller than an integrated amount of UV light in the second irradiation step. According to this aspect, the UV curable resin can be brought into a semi-cured state in the first irradiation step, and the UV curable resin can be brought into a cured state in the second irradiation step. (3) In the manufacturing method according to the above aspect, the integrated light amount of the UV in the first irradiation step is A1 [mW / cm 2 ], the integrated light amount of the UV in the second irradiation step is A2 [mW / cm 2 ], formula (1) may be satisfied. A2 / 100≦A1≦A2 / 10 (1) According to this aspect, the UV curable resin can be brought into a semi-cured state in the first irradiation step, and the UV curable resin can be brought into a cured state in the second irradiation step. (4) In the manufacturing method of the above embodiment, the illuminance of the UV in the first irradiation step may be the same as the illuminance of the UV in the second irradiation step, and the irradiation time of the UV in the first irradiation step may be shorter than the irradiation time of the UV in the second irradiation step. According to this embodiment, by setting the illuminance of UV to be the same in the first irradiation step and the second irradiation step, but setting the irradiation times to be different from each other, it is possible to make the integrated light amount of UV in the first irradiation step smaller than the integrated light amount of UV in the second irradiation step. (5) In the manufacturing method of the above embodiment, the heating step and the first irradiation step may be performed before the molding step. According to this embodiment, the resin layer can be made to have a low fluidity before the molding step, so that the thermoplastic resin sheet on which the resin layer is formed can be easily handled in the molding step. (6) In the manufacturing method of the above aspect, the first irradiation step may be performed after the heating step. According to this aspect, the UV in the first irradiation step can be blocked by the cured thermosetting resin, and the UV curable resin can be put into a semi-cured state. (7) In the manufacturing method of the above aspect, when a reaction force when scratching the resin layer after the first irradiation step is measured using an Erichsen hardness tester, the reaction force may be 0.3 N or more and 1.0 N or less. This makes it possible to impart extensibility and a desired hardness to the resin layer. The present disclosure may be realized in various forms other than the manufacturing method, for example, in the form of a resin molded product. [Brief description of the drawings]

[0007] [Figure 1] 1 is a flowchart showing the steps of a manufacturing process for a resin molded product. [Diagram 2] 1A to 1C are schematic diagrams illustrating each step of a manufacturing process. [Diagram 3] 1A and 1B are diagrams illustrating the relationship between UV irradiation and the cured state of a UV curable resin. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] A. Embodiment: Fig. 1 is a flow chart showing the procedure of the manufacturing process for achieving the method for manufacturing the resin molded product 1. Fig. 2 is a schematic diagram for explaining each step of the manufacturing process.

[0009] As shown by "S20" in FIG. 2, the resin molded product 1 manufactured in this manufacturing process mainly includes a thermoplastic resin sheet 10 and a resin layer 20 disposed on the thermoplastic resin sheet 10. The resin molded product 1 in this embodiment is used for the interior or exterior of a vehicle. The interior of a vehicle is, for example, an automobile seat. The resin layer 20 can impart scratch resistance, chemical resistance, and weather resistance to the resin molded product 1.

[0010] However, if the resin layer 20 is made of a thermosetting resin and the resin layer 20 is thermally cured after the thermoplastic resin sheet 10 is molded, it is necessary to prepare a heating furnace capable of accommodating a molded product having a large volume. The larger the heating furnace, the greater the energy required for heating. Therefore, in this embodiment, before the thermoplastic resin sheet 10 is molded, the resin layer 20 is formed on the thermoplastic resin sheet 10 and the resin layer 20 is cured. This allows the heating furnace for thermally curing the resin layer 20 to be compact, reducing the energy consumption and the CO2 emissions.

[0011] In the case of a manufacturing method in which the thermoplastic resin sheet 10 is molded after the resin layer 20 is formed on the thermoplastic resin sheet 10, the resin layer 20 also needs to be deformable along the mold. In other words, the resin layer 20 is required to have extensibility. In addition, the resin layer 20 is required to have a hardness such that no trace is left on the resin layer 20 even when pressure is applied to the resin layer 20 in a process after molding.

[0012] The inventors have found that by using a resin 30 containing a UV curable resin 31 and a thermosetting resin 32 as a resin material for forming the resin layer 20, and by heating the resin layer 20 and irradiating it with UV (ultraviolet rays) so that the integrated light amount is within a specific range before molding, the resin layer 20 can be adjusted to a desired hardness while having extensibility. They have also found that by irradiating the resin layer 20 with UV again after molding, the resin layer 20 can be given appropriate scratch resistance, chemical resistance, and weather resistance. This will be described in detail below.

[0013] Hereinafter, steps in the manufacturing process will be referred to as "S". In S10 as an application step in FIG. 1, resin 30 is applied to thermoplastic resin sheet 10 to form resin layer 20. In this embodiment, the thickness of resin layer 20 is about 5 μm or more and 25 μm or less. As shown in "S10" in FIG. 2, resin 30 includes UV curable resin 31 and thermosetting resin 32. Thermosetting resin 32 is in the form of particles and is dispersed in UV curable resin 31. In this embodiment, resin 30 is transparent, but colored resin 30 may be used.

[0014] AES resin can be used as the material of the thermoplastic resin sheet 10. Acrylic resin can be used as the UV curable resin 31. Acrylic urethane resin can be used as the thermosetting resin 32. In the following description, "thermoplastic resin sheet 10 on which the resin layer 20 is formed" may be referred to as "laminated sheet LS." A roll coater, a slit coater, or the like can be used as a device for applying the resin 30 to the thermoplastic resin sheet 10.

[0015] 1, the laminated sheet LS is heated in a heating furnace so that the thermosetting resin 32 contained in the resin layer 20 is cured. In this embodiment, the heating temperature is about 90° C. or more and 120° C. or less. In this embodiment, the heating time is about 5 minutes or more and 20 minutes or less.

[0016] 1, the laminated sheet LS is irradiated with UV so that the UV-curable resin 31 contained in the resin layer 20 is in a semi-cured state. This makes it possible to impart extensibility and hardness to the resin layer 20 such that it is unlikely to leave a mark when pressure is applied. Specifically, in S14 of this embodiment, the illuminance is 250 mW / cm 2 of UV, with an integrated light intensity of 20 mJ / cm 2 In this embodiment, the laminated sheet LS is irradiated with UV light using a UV light so that the laminated sheet LS is irradiated with UV light.

[0017] In this manufacturing process, there are two steps of irradiating UV to harden the UV curable resin 31: S14 and S20, which will be described later. Comparing S14 and S20, the integrated amount of UV light in S14 is smaller than the integrated amount of UV light in S20. The integrated amount of UV light in S14 is A1 [mW / cm 2 ], and the cumulative amount of UV light at S20 is A2 [mW / cm 2 ], A1 and A2 satisfy the following formula (1). A2 / 100≦A1≦A2 / 10 (1)

[0018] Here, the semi-cured state is a state before reaching a cured state. When the UV curable resin 31 contained in the resin layer 20 is continuously irradiated with UV of a certain illuminance, it changes from an initial state having fluidity to a cured state as the irradiation time becomes longer. The state of the UV curable resin 31 can be evaluated by the hardness of the resin layer 20. When the relationship between the irradiation time and the hardness is examined, and the state in which the rate of change in hardness, which is the amount of change in hardness per unit irradiation time of UV, is equal to or less than a reference value is defined as the cured state, the semi-cured state refers to a state in which the rate of change in hardness is greater than the reference value. In this embodiment, the semi-cured state of the UV curable resin 31 is evaluated by the hardness of the resin layer 20. Then, in S14 in which the UV curable resin 31 is brought into the semi-cured state, the irradiation conditions of the UV are adjusted so that the hardness of the resin layer 20 falls within a predetermined hardness range. Specifically, the hardness range is a range in which the reaction force measured when the resin layer 20 after S14 is scratched using an Erichsen hardness tester is 0.3 N or more and 1.0 N or less.

[0019] The state of the UV curable resin 31 can also be evaluated by the viscosity of the resin layer 20. As in the case of hardness described above, when the relationship between irradiation time and viscosity is examined and the cured state is defined as a state in which the rate of change in viscosity, which is the amount of change in viscosity per unit UV irradiation time, is equal to or less than a reference value, the semi-cured state is a state in which the rate of change in viscosity is greater than the reference value.

[0020] FIG. 3 is a diagram for explaining the relationship between UV irradiation and the cured state of the UV curable resin 31 in S14. When UV is irradiated to the resin 30 including the thermosetting resin 32 and the UV curable resin 31, it is considered that the UV is blocked by the thermosetting resin 32, and the curing of the UV curable resin 31 is inhibited. Furthermore, it is considered that the closer to the thermoplastic resin sheet 10 in the resin layer 20, the more difficult it is for the UV to reach the position, and the curing is inhibited. In this way, by using the resin 30 including not only the UV curable resin 31 but also the thermosetting resin 32, the UV curable resin 31 can be brought into a semi-cured state. Note that the content of the UV curable resin 31 and the content of the thermosetting resin 32 in the resin 30 are specified and adjusted in advance by experiments, etc., so that the semi-cured state is realized in S12.

[0021] The inventors have confirmed that when UV is applied to a resin layer 20 that does not contain a thermosetting resin 32 and contains only a UV-curable resin 31, it is not easy to bring the resin layer 20 into a semi-cured state even if the UV illuminance and irradiation time are limited. That is, in this manufacturing method, by using a resin 30 that contains a thermosetting resin 32 and a UV-curable resin 31, and adjusting the UV irradiation conditions, it is possible to bring the resin 30 into a semi-cured state.

[0022] 1, a laminate sheet LS is formed by a vacuum forming method in S16 as a forming step. Specifically, as shown in "S16" in Fig. 2, in a state where the laminate sheet LS including the thermoplastic resin sheet 10 plasticized by heating is placed on a vacuum forming mold 81, the inside of the vacuum forming mold 81 is suctioned by vacuum. As a result, the laminate sheet LS is formed along the vacuum forming mold 81.

[0023] As described above, the UV curable resin 31 is in a semi-cured state. Furthermore, the thermosetting resin 32 of this embodiment has a property of being deformable by an external force even after curing. Therefore, in S16, the laminated sheet LS can be deformed along the vacuum forming die 81. When the deformation of the laminated sheet LS is completed, the laminated sheet LS is cooled until the thermoplastic resin sheet 10 is in a solidified state. Thereafter, the laminated sheet LS is removed from the vacuum forming die 81.

[0024] 1, the foam layer 40 is formed. Specifically, the molded laminated sheet LS is fitted into the upper die 82. Here, the hardness of the resin layer 20 is within a predetermined hardness range. Therefore, even when the laminated sheet LS is fitted into the upper die 82, a mold mark is prevented from remaining on the resin layer 20.

[0025] After the molded laminate sheet LS is fitted into the upper die 82, the upper die 82 with the laminate sheet LS fitted therein is placed on a lower die 83. An internal space 84 is formed between the molded laminate sheet LS and the lower die 83. A foaming resin material is injected into the internal space 84 through a flow path (not shown). As a result, the internal space 84 is filled with the foaming resin material, and a foam layer 40 is formed under the laminate sheet LS. In this embodiment, the material of the foaming layer 40 is foamed polyurethane.

[0026] In S20 as a second irradiation step in FIG. 1, UV is irradiated onto the resin layer 20 so that the UV curable resin 31 is in a cured state, and this manufacturing process is completed.

[0027] As described above, the integrated amount of UV light in S20 is greater than the integrated amount of UV light in S14. Specifically, in the S20 of this embodiment, the illuminance is 250 mW / cm 2 The UV has an accumulated light intensity of 2000mJ / cm 2 As a result, the UV curable resin 31 is cured, and the resin molded product 1 is endowed with appropriate scratch resistance, chemical resistance, and weather resistance.

[0028] According to the embodiment described above, the manufacturing process of the resin molded product 1 includes S10, S12, S14, S16, and S20. In S10, the resin 30 containing the UV curable resin 31 and the thermosetting resin 32 is applied to the thermoplastic resin sheet 10 to form the resin layer 20. In S12, the resin layer 20 is heated so that the thermosetting resin 32 is in a cured state. In S14, UV is irradiated to the resin layer 20 so that the UV curable resin 31 is in a semi-cured state. S12 and S14 are performed before the molding of the thermoplastic resin sheet 10 in S16 is completed. Note that "the molding in S16 is completed" means that "after the thermoplastic resin sheet 10 is molded, the thermoplastic resin sheet 10 is cooled to be in a solidified state." By performing S12 and S14, it is possible to impart extensibility and a desired hardness to the resin layer 20. Therefore, in S16, the laminate sheet LS can be appropriately molded, and even when the molded laminate sheet LS is fitted into the upper die 82 in S18, it is possible to make it difficult for a mold mark to remain on the resin layer 20.

[0029] The integrated amount of UV light in S14 is smaller than the integrated amount of UV light in S20. 2 ], and the cumulative amount of UV light at S20 is A2 [mW / cm 2 ], formula (1) is satisfied. As a result, the UV curable resin 31 can be brought into a semi-cured state in S14, and the UV curable resin 31 can be brought into a cured state in S20.

[0030] The UV illuminance in S14 is the same as the UV illuminance in S20. The UV irradiation time in S14 is shorter than the UV irradiation time in S20. Therefore, by setting the UV illuminance to be the same in S14 and S20 but setting the irradiation times to be different from each other, it is possible to make the integrated amount of UV light in S14 smaller than the integrated amount of UV light in S20.

[0031] Moreover, S12 and S14 are performed before S16. The resin 30 in the initial state has fluidity. Therefore, before molding in S16, the UV curable resin 31 is put into a semi-cured state and the thermosetting resin 32 is put into a cured state. This makes it possible to easily handle the laminated sheet LS in S16 where molding is performed. Moreover, S14 is performed after S12. This makes it possible to block the irradiated UV by the cured thermosetting resin 32 in S14.

[0032] B. Other embodiments: (B1) In the above embodiment, S12, which heats the laminated sheet LS, is performed before S14, which irradiates the laminated sheet LS with UV. The order of S12 and S14 is not limited to this. For example, S14 may be performed before S12, or S12 and S14 may be performed in parallel. The thermosetting resin 32 blocks the irradiated UV even in the initial state before it is cured. For this reason, the UV curable resin 31 can be made semi-cured by using the resin 30. In addition, the heat for plasticizing the thermoplastic resin sheet 10 in S16 may be used as the heat for curing the thermosetting resin 32. That is, S12 and S16 may be performed in parallel. By curing the thermosetting resin 32 before the molding of the laminated sheet LS is completed, it is possible to avoid using a large heating furnace for heating the molded product of the laminated sheet LS, thereby reducing CO2 emissions.

[0033] (B2) In the above embodiment, the integrated amount of UV light in S14 and the integrated amount of UV light in S20 satisfy the formula (1). The integrated amount of UV light in S14 and S20 is not limited to this. The integrated amount of UV light in S14 and S20 may be appropriately set according to the characteristics of the resin 30.

[0034] (B3) In the above embodiment, the UV illuminance in S14 is the same as the UV illuminance in S20, and the UV irradiation time in S14 is shorter than the UV irradiation time in S20. The UV irradiation conditions in S14 and S20 are not limited to this. For example, the UV irradiation time in S14 and the UV irradiation time in S20 may be set to be the same, and the UV illuminance in S14 may be set to be smaller than the UV illuminance in S20. In addition, both the UV illuminance and the irradiation time may be set to be different between S14 and S20. By setting the integrated amount of UV light in S14 to be smaller than the integrated amount of UV light in S20, the UV curable resin 31 can be easily adjusted to a semi-cured state in S14.

[0035] (B4) In the above embodiment, the resin molded product 1 includes the foam layer 40, but the present manufacturing method can also be applied to a resin molded product 1 that does not include the foam layer 40. In the process after S16, the laminated sheet LS is grasped and transported, for example, by a robot. When being grasped, pressure is applied to the laminated sheet LS. Here, the desired hardness is imparted to the resin layer 20 by S12 and S14. Therefore, even when pressure is applied by grasping, it is possible to make it difficult for a trace of grasping to remain on the resin layer 20.

[0036] The present disclosure is not limited to the above-mentioned embodiment, and can be realized in various configurations without departing from the spirit of the present disclosure. For example, the technical features of the embodiments corresponding to the technical features in each aspect described in the Summary of the Invention can be appropriately replaced or combined to solve some or all of the above-mentioned problems or to achieve some or all of the above-mentioned effects. Furthermore, if a technical feature is not described as essential in this specification, it can be appropriately deleted. [Explanation of symbols]

[0037] Reference Signs List 1... resin molded product, 10... thermoplastic resin sheet, 20... resin layer, 30... resin, 31... UV cured resin, 32... thermosetting resin, 40... foam layer, 81... vacuum forming mold, 82... upper mold, 83... lower mold, 84... internal space, LS... laminated sheet

Claims

1. A method for manufacturing a resin molded product, comprising the steps of: A coating step of coating a resin including a UV curable resin and a thermosetting resin on a thermoplastic resin sheet to form a resin layer; a heating step of heating the resin layer so that the thermosetting resin is in a cured state; a first irradiation step of irradiating the resin layer with UV light so that the UV curable resin is in a semi-cured state; A molding step of molding the thermoplastic resin sheet on which the resin layer is formed; A second irradiation step of irradiating the resin layer with UV light after the molding step so that the UV curable resin is in a cured state, The manufacturing method, wherein the first irradiation step and the heating step are performed until molding in the molding step is completed.

2. The method according to claim 1, A manufacturing method, wherein an integrated amount of UV light in the first irradiation step is smaller than an integrated amount of UV light in the second irradiation step.

3. The method according to claim 2, The integrated amount of UV light in the first irradiation step is A1 [mW / cm ２ ], the integrated light amount of the UV in the second irradiation step is A2 [mW / cm ２ ] satisfies formula (1). A2 / 100≦A1≦A2 / 10...(1)

4. The method according to claim 2, The irradiance of the UV in the first irradiation step is the same as the irradiance of the UV in the second irradiation step; A manufacturing method, wherein the UV irradiation time in the first irradiation step is shorter than the UV irradiation time in the second irradiation step.

5. The method according to claim 1, The manufacturing method, wherein the heating step and the first irradiation step are performed before the molding step.

6. The method according to claim 5, The manufacturing method, wherein the first irradiation step is performed after the heating step.

7. The method according to claim 6, further comprising the steps of: the reaction force when scratched is measured using an Erichsen hardness tester on the resin layer after the first irradiation step, and the reaction force is 0.3 N or more and 1.0 N or less.

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