Joining method for thermoset FRP member and thermoplastic FRP member
A spacer-based method for joining thermosetting and thermoplastic FRP members controls heat conduction, preventing deformation and thermal degradation, enabling a stable joint.
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- IHI AEROSPACE CO LTD
- Filing Date
- 2024-12-19
- Publication Date
- 2026-06-25
AI Technical Summary
Existing methods for joining thermosetting FRP and thermoplastic FRP members fail due to excessive temperature rise in the thermosetting FRP, leading to deformation and thermal degradation during the welding process.
A method involving the use of a spacer made of thermoplastic FRP between the thermosetting and thermoplastic FRP members, where the spacer is integrally molded with a laminate of thermosetting FRP and then welded to the thermoplastic FRP member, controlling heat conduction to prevent excessive temperature rise.
Prevents deformation and thermal degradation of the thermosetting FRP by maintaining the temperature below its heat resistance, ensuring a stable joint without resin degradation.
Smart Images
Figure JP2024044971_25062026_PF_FP_ABST
Abstract
Description
Joining method for a member made of thermosetting FRP and a member made of thermoplastic FRP
[0001] The present disclosure relates to a method for joining a member made of FRP containing a thermosetting resin (thermosetting FRP) and a member made of FRP containing a thermoplastic resin (thermoplastic FRP).
[0002] As a method for joining members made of thermoplastic FRP, a method has been proposed in which two joined members are heated to melt the thermoplastic resin contained in both members, and the two members are joined through the melted thermoplastic resin, that is, direct heat welding.
[0003] Patent Document 1 proposes a method for joining a first member and a second member both made of a material containing a thermoplastic resin, in which the first member is placed on a first heat source, the second member is placed on the first member, and after positioning a second heat source above the second member, the second heat source is lowered and its lower surface is pressed against the upper surface of the second member. At this time, the temperature of the first heat source is set to a temperature lower than the melting point of the thermoplastic resin, while the temperature of the second heat source is set to a temperature higher than the melting point of the thermoplastic resin and lower than the thermal decomposition temperature.
[0004] By setting the temperatures of the first heat source and the second heat source as described above, in the joined members (the first member and the second member), the portion having a temperature equal to or higher than the melting point of the thermoplastic resin is limited to the second member and the vicinity of the joint surface of both members. That is, regarding the first member among the joined members, the temperature of the portion excluding the vicinity of the joint surface is suppressed to a temperature lower than the melting point of the thermoplastic resin. Therefore, welding is surely performed at the joint surface, while the flow of the thermoplastic resin is suppressed at other portions of the first member, and deformation of the joined members can be prevented.
[0005] International Publication No. 2024 / 214288
[0006] When joining two members made of FRP, if the FRP constituting both members is thermoplastic FRP, the method of Patent Document 1 can be applied. However, when one of the two members is thermoplastic FRP and the other is thermosetting FRP, as will be described below, the method of Patent Document 1 cannot be applied.
[0007] The minimum temperature at which super engineering plastics (super engineering plastics), which are widely used as thermoplastic resins in thermoplastic FRP due to their high heat resistance and mechanical strength, can be welded, such as their melting point or glass transition temperature, is generally 100°C or more higher than the heat resistance temperature of thermosetting resins. For example, while the heat resistance temperature of epoxy resin is 100 to 200°C, the crystalline melting point of PEEK (polyether ether ketone) is approximately 340°C or higher, and the glass transition temperature of PEI (polyether imide) is approximately 210°C or higher. Therefore, when attempting to join a member made of thermoplastic FRP containing super engineering plastic as a thermoplastic resin (thermoplastic FRP member) and a member made of thermosetting FRP (thermosetting FRP member) using the method described in Patent Document 1, during the joining process, the temperature of the thermosetting FRP member rises significantly above the heat resistance temperature of the thermosetting resin contained in the thermosetting FRP due to heat conduction from the heat source and the molten thermoplastic FRP member, leading to deformation of the thermosetting FRP and thermal degradation of the thermosetting resin. For this reason, the method described in Patent Document 1 cannot be applied to joining a thermosetting FRP member and a thermoplastic FRP member.
[0008] This disclosure has been made in view of the above-mentioned problems, and aims to provide a method for joining a member made of thermosetting FRP and a member made of thermoplastic FRP, which does not cause deformation of the thermosetting FRP or thermal degradation of the thermosetting resin contained in the thermosetting FRP.
[0009] To solve the above problems, the present disclosure provides a method for joining a member made of FRP containing a thermosetting resin and a member made of FRP containing a thermoplastic resin, comprising the steps of: (a) preparing a laminate that will become the first member by being molded using a prepreg containing the thermosetting resin; (b) preparing a spacer made of FRP containing a thermoplastic resin and having a first surface and a second surface, wherein the first surface is in close contact with the joining surface of the laminate and the second surface is in close contact with the joining surface of the second member; (c) integrally molding the laminate and the spacer with the joining surface of the laminate and the first surface of the spacer in close contact, thereby making the laminate the first member; and (d) welding the spacer and the second member with the second surface of the spacer integrated with the first member in step (c) in close contact with the joining surface of the second member.
[0010] According to this disclosure, when joining a member made of thermosetting FRP and a member made of thermoplastic FRP, it is possible to obtain excellent effects such as preventing deformation of the thermosetting FRP and thermal degradation of the thermosetting resin contained in the thermosetting FRP.
[0011] This is a schematic diagram showing the state immediately before implementing the method of the embodiment of this disclosure. This is a schematic diagram showing the state immediately before implementing the welding process in the method of the embodiment of this disclosure. This is a schematic diagram showing the state during and after the welding process in the method of the embodiment of this disclosure. This is a flowchart showing the method of the embodiment of this disclosure.
[0012] The embodiments of this disclosure will be described in detail below with reference to the drawings.
[0013] Figure 1 is a schematic diagram showing the state immediately before implementing the method of the embodiment of this disclosure, Figure 2 is a schematic diagram showing the state immediately before implementing the welding process in the method of the embodiment of this disclosure, and Figure 3 is a schematic diagram showing the state during and after the welding process in the method of the embodiment of this disclosure.
[0014] In the method of the embodiment of the present disclosure, a first member 10 made of FRP containing a thermosetting resin (thermosetting FRP) and a second member 20 made of FRP containing a thermoplastic resin (thermoplastic FRP) are joined together.
[0015] As mentioned above, the problem with joining the first member 10 and the second member 20 using the method described in Patent Document 1 is that the temperature of the first member 10 rises excessively during the welding process due to heat conduction from the heat source and the second member 20. Therefore, in the method of the embodiment of this disclosure, a spacer 30 is used, which is placed between the two members as described later, in order to suppress this heat conduction.
[0016] In carrying out the method of the embodiment of this disclosure, the three components shown in Figure 1 are prepared in advance.
[0017] 10' is a laminate obtained by cutting and laminating a prepreg made of thermosetting resin and reinforcing fibers. After being integrally molded with the spacer 30 as described later, the laminate 10' becomes the first member 10, which is one of the members to be joined.
[0018] The other member to be joined, the second member 20, is made of thermoplastic FRP and is obtained by cutting and laminating a prepreg made of thermoplastic resin and reinforcing fibers and then molding it.
[0019] The spacer 30 is a sheet-like member made of thermoplastic FRP, similar to the second member 20, and is obtained by cutting and laminating a prepreg made of thermoplastic resin and reinforcing fibers, and then molding it. The shape of the spacer 30 is such that its lower surface 30L (first surface) is in close contact with the upper surface 10U (joint surface) of the laminate 10', and its upper surface 30U (second surface) is in close contact with the lower surface 20L (joint surface) of the second member 20.
[0020] As will be described later, the spacer 30 is integrally molded with the laminate 10' and welded to the second member 20, thereby acting as a mediator in joining the first member 10 and the second member 20. In preparation for integral molding with the laminate 10', the lower surface 30L of the spacer 30 is subjected to a surface treatment to improve adhesion with the upper surface 10U of the laminate 10', as will be described later.
[0021] In the method of the embodiment of this disclosure, the first member 10 and the second member 20 are joined by welding the spacer 30 and the second member 20 together, but prior to this welding process, the laminate 10' and the spacer 30 are integrally molded.
[0022] That is, before carrying out the welding process in the method of the embodiment of this disclosure, as shown in Figure 2, the spacer 30 is placed on the laminate 10' (with the upper surface 10U of the laminate 10' and the lower surface 30L of the spacer 30 in close contact), and these are integrally molded. After this step, the laminate 10' becomes the first member 10.
[0023] Then, the second member 20 is placed on the spacer 30 which is integrated with the first member 10 (with the lower surface 20L of the second member 20 and the upper surface 30U of the spacer 30 in close contact), and the welding process of the spacer 30 and the second member 20 is carried out (see Figure 3).
[0024] In this way, the first member 10 and the second member 20 are joined via the spacer 30, by pre-forming the laminate 10' that will become the first member 10 and the spacer 30 as a single unit, and then welding the spacer 30 to the second member 20.
[0025] Next, each step of the method according to the embodiment of this disclosure will be described below with reference to the flowchart shown in Figure 4.
[0026] In step S100, a laminate 10' is prepared by cutting and laminating a prepreg made of thermosetting resin and reinforcing fibers.
[0027] In parallel with this, in step S200, a laminate to become the second member 20 is prepared by cutting and laminating a prepreg made of thermoplastic resin and reinforcing fibers. Note that this step may be omitted if injection molding is performed in the subsequent step S210.
[0028] The laminate that will become the second member 20 is formed into a predetermined shape and dimensions in the subsequent step S210 by an appropriate method such as press molding, autoclave molding, or injection molding, and becomes the second member 20.
[0029] Furthermore, in parallel with the above, in step S300, a laminate to be used as a spacer 30 is prepared by cutting and laminating a prepreg made of thermoplastic resin and reinforcing fibers. Note that this step may be omitted if injection molding is performed in the following step S310.
[0030] In the subsequent step S310, the laminate that will become the spacer 30 is formed into a predetermined shape and dimensions by an appropriate method such as press molding, autoclave molding, or injection molding, and becomes the spacer 30.
[0031] In the subsequent step S320, the molded spacer 30 has its lower surface 30L (the surface facing the upper surface 10U of the laminate 10') subjected to surface treatment. This surface treatment aims to improve the adhesion between the spacer 30 and the laminate 10'. In addition to surface cleaning, this surface treatment also serves to remove any remaining mold release agent if the spacer 30 was molded using a mold release agent. Specific methods include blasting, plasma treatment, corona treatment, and other appropriate methods. In cases where the lower surface 30L of the spacer 30 can be roughened (i.e., minute irregularities can be formed), a so-called anchoring effect can also be obtained. Furthermore, a primer or adhesive may be applied to improve the bonding strength between the spacer 30 and the laminate 10'.
[0032] Next, in step S400, the laminate 10' and the spacer 30 are integrally molded. Specifically, the spacer 30, whose lower surface 30L has been surface-treated, is placed on top of the laminate 10', and in this state, the laminate 10' and the spacer 30 are integrally molded by an appropriate molding method such as press molding or autoclave molding. During this integral molding process, the laminate 10' is heated to a temperature above the curing temperature of the thermosetting FRP that constitutes it, and becomes a first member 10 having a predetermined shape and dimensions.
[0033] Next, in step S330, the upper surface 30U of the spacer 30, which is integrated with the first member 10 (the surface facing the lower surface 20L of the second member 20), is subjected to surface treatment. This surface treatment aims to improve the adhesion between the spacer 30 and the second member 20. In addition to surface cleaning, this surface treatment also serves to remove any remaining mold release agent if the spacer 30 was molded using a mold release agent. Specific methods include blasting, plasma treatment, corona treatment, and other appropriate methods. In the case of a method that can roughen the upper surface 30U of the spacer 30 (i.e., create minute irregularities), a so-called anchoring effect can also be obtained. Note that the surface treatment in step S330 may also be performed in step S320 as described above.
[0034] Furthermore, if the spacer 30 is molded using a method that does not use a mold release agent, if the required bonding strength between the spacer 30 and the laminate 10' and the second member 20 is not high, or if the lower surface 30L and upper surface 30U of the spacer 30 can be roughened simultaneously with molding by ingenuity during the molding process, the surface treatment in steps S320 and S330 may be omitted.
[0035] Finally, in step S600, the second member 20 is placed on the spacer 30 which is integrated with the first member 10, and a welding process is performed between the spacer 30 and the second member 20. Specifically, one of the following methods can be used: resistance welding, ultrasonic welding, conduction welding, induction welding, or laser welding.
[0036] Through the above steps, the first member 10 and the second member 20 are joined together via the spacer 30. In the welding process between the spacer 30 and the second member 20 (step S600), the area near the contact surface (joining surface) between the two reaches the melting temperature of the thermoplastic resin. However, since the spacer 30 acts as a resistance to heat conduction from this area, the temperature of the area near the contact surface between the spacer 30 and the first member 10 (and consequently, the entire first member 10) is kept below the heat resistance temperature of the thermosetting resin, preventing thermal degradation of the resin and deformation of the thermosetting FRP.
[0037] Thus, according to the method of the embodiment of the present disclosure, a first member 10 made of thermosetting FRP and a second member 20 made of thermoplastic FRP can be joined without causing deformation of the thermosetting FRP contained in the thermosetting FRP or thermal degradation of the thermosetting resin.
[0038] Of the steps described above, S100, S200, S210, S300, and S310 can be considered as preparation steps (SP in Figure 4) of the method according to the embodiment of the present disclosure, and S320, S400, and S600 can be considered as the main steps (SM in Figure 4) of the method according to the embodiment of the present disclosure.
[0039] Furthermore, the thermal resistance of the spacer 30 (in other words, the temperature difference between the upper and lower surfaces of the spacer 30) can be adjusted by changing the thickness of the spacer 30. For example, by making the spacer 30 thicker, the temperature difference between the upper and lower surfaces of the spacer 30 becomes larger, and the overall temperature of the first member 10 can be kept lower.
[0040] Alternatively, the thermal resistance of the spacer 30 can also be adjusted by changing the material of the reinforcing fibers contained in the thermoplastic FRP that constitutes the spacer 30. For example, by changing the reinforcing fibers from carbon fibers to glass fibers, which have lower thermal conductivity, the temperature difference between the upper and lower surfaces of the spacer 30 becomes larger, and the overall temperature of the first member 10 can be kept lower.
[0041] Furthermore, the thermoplastic FRP constituting the spacer 30 and the thermoplastic FRP constituting the second member 20 may contain the same or different thermoplastic resins. However, if the thermoplastic resins contained in both FRPs are different, it is desirable that their minimum temperatures at which welding is possible, such as melting points or glass transition temperatures, do not differ significantly. This avoids the need to excessively heat the thermoplastic resin with the lower minimum welding temperature to a high temperature during the welding process.
[0042] Furthermore, the method of the embodiment of this disclosure can be implemented as long as the shape and dimensions of the first member 10 and the second member 20 are such that heating can be applied to the contact surface (joining surface) between the spacer 30 and the second member 20 in the welding process using any of the methods described above.
[0043] Furthermore, in Figures 1 to 3, the first member 10 is shown as having a flat plate shape, and the second member 20 is shown as having an L-shaped cross-section. However, the shapes of both members can be any shape as long as they can ensure surfaces that are in close contact with both sides of the spacer 30.
[0044] (Aspects of the Disclosure) A method according to a first aspect of the Disclosure is for joining a first member made of FRP containing a thermosetting resin and a second member made of FRP containing a thermoplastic resin, and includes, in this order: (a) preparing a laminate that will become the first member by being molded using a prepreg containing the thermosetting resin; (b) preparing a spacer made of FRP containing a thermoplastic resin and having a first surface and a second surface, wherein the first surface is in close contact with the joining surface of the laminate and the second surface is in close contact with the joining surface of the second member; (c) integrally molding the laminate and the spacer with the joining surface of the laminate and the first surface of the spacer in close contact, thereby making the laminate the first member; and (d) welding the spacer and the second member with the second surface of the spacer integrated with the first member in step (c) in close contact with the joining surface of the second member.
[0045] In the method according to the second aspect of the present disclosure, prior to the step (c), at least one surface treatment is performed on the first surface of the spacer formed in the step (b) for the purpose of removing a release agent adhered to the first surface, roughening the first surface, and improving the bonding strength between the first surface and the first member.
[0046] 10 First member 10' Laminate 10U Upper surface (bonding surface) of the first member 20 Second member 20L Lower surface (bonding surface) of the second member 30 Spacer 30L Lower surface of the spacer 30U Upper surface of the spacer
Claims
1. A method for joining a first member made of FRP containing a thermosetting resin and a second member made of FRP containing a thermoplastic resin, comprising the steps of: (a) preparing a laminate that will become the first member by being molded using a prepreg containing the thermosetting resin; (b) preparing a spacer made of FRP containing a thermoplastic resin and having a first surface and a second surface, wherein the first surface is in close contact with the joining surface of the laminate and the second surface is in close contact with the joining surface of the second member; (c) integrally molding the laminate and the spacer with the joining surface of the laminate and the first surface of the spacer in close contact, thereby making the laminate the first member; and (d) welding the spacer and the second member with the second surface of the spacer integrated with the first member in step (c) in close contact with the joining surface of the second member.
2. The method according to claim 1, wherein, prior to step (c), the first surface of the spacer formed in step (b) is subjected to a surface treatment aimed at at least one of the following: removal of mold release agent adhering to the first surface, roughening of the first surface, and improvement of the bonding strength between the first surface and the first member.