Substrate for fiber-reinforced plastic, fiber-reinforced plastic, and method for producing same

Abstract

To provide a substrate for a fiber-reinforced plastic having heightened reinforcement effect, without lowering heat resistance, the fiber-reinforced plastic and a manufacturing method thereof.SOLUTION: A substrate for fiber-reinforced plastics includes reinforcing fibers, as a matrix resin, a first matrix resin and a second matrix resin different from the first matrix resin. The first matrix resin is a super engineering plastic fiber, the second matrix resin is a thermoplastic engineering plastic fiber, and a volume ratio of the first matrix resin to the second matrix resin is 90:10 to 25:75. With the above structure, by using the matrix resin as two components, it is possible to realize a fiber-reinforced plastic with enhanced reinforcing effect without reducing heat resistance.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a substrate for fiber-reinforced plastic, a fiber-reinforced plastic, and a method for producing the same. [Background technology]

[0002] Fiber-reinforced plastics, which are composites of reinforcing fibers such as carbon fibers and a matrix resin, are used in a variety of fields. Thermosetting resins, such as epoxy resins and polyimide resins, are often used as the matrix resin. Because such fiber-reinforced plastics generally use thermosetting resins, they have issues such as long molding times. Therefore, fiber-reinforced plastics using thermoplastic resins as the matrix resin have been proposed. Generally, low-cost general-purpose plastics such as modified polypropylene and polyethylene terephthalate have been considered. Fiber-reinforced plastics using engineering plastics (engineering plastics) such as polyamide (PA) as the matrix resin have also been proposed. However, fiber-reinforced plastics using such resins have a problem of poor heat resistance. Therefore, in fields requiring higher heat resistance, the use of super-engineering plastics (super-engineering plastics) such as polyethyleneimide (PEI) and polyphenylene sulfide (PPS) as the matrix resin has been considered (e.g., Patent Documents 1 and 2).

[0003] However, when PEI or PPS is used as the matrix resin, the strength and elastic modulus are inferior to those of engineering plastics. Thus, it has been difficult for conventional fiber-reinforced plastics to achieve both heat resistance and strength. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 5949895 [Patent Document 2] Patent No. 6586773 Summary of the Invention [Problem to be solved by the invention]

[0005] An object of the present disclosure is to provide a substrate for fiber-reinforced plastics, a fiber-reinforced plastic, and a method for producing the same, which have an improved reinforcing effect without reducing heat resistance.

[0006] A fiber-reinforced plastic substrate according to a first aspect of the present invention includes reinforcing fibers and matrix resins, including a first matrix resin and a second matrix resin different from the first matrix resin, wherein the first matrix resin is a super engineering plastic fiber and the second matrix resin is a thermoplastic engineering plastic fiber, and the volume ratio of the first matrix resin to the second matrix resin is 90:10 to 25:75. With this configuration, by using a two-component matrix resin, a fiber-reinforced plastic with enhanced reinforcing effect can be realized without reducing heat resistance.

[0007] Furthermore, according to a second aspect of the present invention, in the substrate for fiber-reinforced plastics, the super engineering plastic fibers of the first matrix resin are at least one of polyetherimide fibers, polyphenylene sulfide fibers, polyetheretherketone fibers, polyetherketoneketone fibers, polyethersulfone fibers, thermoplastic polyimide fibers, polyvinylidene fluoride fibers, perfluoroalkoxyalkane fibers, liquid crystal polymer fibers, and polycarbonate fibers; the thermoplastic engineering plastic fibers of the second matrix resin are polyamide fibers; and the reinforcing fibers are any of carbon fibers, glass fibers, basalt fibers, silica fibers, Tyranno fibers, alumina fibers, and organic fibers.

[0008] Furthermore, according to a third aspect of the present invention, in the substrate for fiber-reinforced plastics according to any one of the above aspects, the melting point of the polyamide fibers is 170° C. or higher.

[0009] Furthermore, according to a fourth aspect of the present invention, in the substrate for fiber-reinforced plastics according to any one of the above aspects, the melting point of the polyamide fibers is 200°C to 270°C.

[0010] Furthermore, according to a fifth aspect of the present invention, in any of the above aspects, a test piece of 15 mm × 100 mm × 1 mm thick is heated in a thermostatic oven at 210°C for 20 minutes, and the thickness is measured at three points, one at the center and one at each end, and the average thickness is defined as thickness change rate [%] = (thickness after heating) / (thickness before heating) × 100, and is 140% or less.

[0011] Furthermore, according to a sixth aspect of the present invention, in the substrate for fiber-reinforced plastics in any of the above aspects, the polyamide fiber is either a recycled polyamide resin fiber or a plant-derived biomass polyamide fiber.

[0012] Furthermore, according to a seventh aspect of the present invention, in the substrate for fiber-reinforced plastics according to any one of the above aspects, the organic fiber of the reinforcing fiber is an aramid fiber.

[0013] Furthermore, according to an eighth aspect of the present invention, there is provided a substrate for fiber-reinforced plastics in any one of the above aspects, wherein the reinforcing fibers include recycled fibers.

[0014] Furthermore, according to a ninth aspect of the present invention, the substrate for fiber-reinforced plastic is any one of the above aspects, further comprising a binder resin, and the binder resin is a heat-and-moisture binder fiber.

[0015] Furthermore, according to a tenth aspect of the present invention, in the substrate for fiber-reinforced plastics in any one of the above aspects, the heat-and-moisture binder fiber is either a polyvinyl alcohol fiber or an ethylene-vinyl alcohol copolymer fiber.

[0016] Furthermore, a fiber-reinforced plastic molded article according to an eleventh aspect of the present invention is a fiber-reinforced plastic molded article obtained by hot-press molding the substrate for fiber-reinforced plastic according to any one of the above aspects.

[0017] Furthermore, a method for producing a fiber-reinforced plastic substrate according to a twelfth aspect of the present invention includes a step of molding a mixed mat material from a matrix resin containing a first matrix resin (super engineering plastic fiber) and a second matrix resin (thermoplastic engineering plastic fiber) in a volume ratio of 90:10 to 25:75, the matrix resin being one of carbon fiber, glass fiber, basalt fiber, silica fiber, Tyranno fiber, alumina fiber, and organic fiber as reinforcing fibers, and a binder resin (heat-and-moisture binder fiber). This two-component matrix resin makes it possible to realize a fiber-reinforced plastic with enhanced reinforcing effect without reducing heat resistance.

[0018] Furthermore, according to a thirteenth aspect of the present invention, in the method for producing a substrate for fiber reinforced plastics according to any one of the above aspects, the thickness of the mixed mat material after molding is 0.05 mm to 3.0 mm.

[0019] Furthermore, according to a fourteenth aspect of the present invention, a method for producing a fiber-reinforced plastic molded body includes a step of press-molding one or more mixed mat materials of a fiber-reinforced plastic substrate produced by the method for producing a fiber-reinforced plastic substrate according to any one of the above aspects. [Brief explanation of the drawings]

[0020] [Figure 1]1 is a graph showing the relationship between the proportion of PA6 and the tensile strength in the fiber-reinforced plastic molded articles according to Examples 1 to 4 and Comparative Examples 1 and 2. [Figure 2] 1 is a graph showing the relationship between the proportion of PA6 and tensile modulus in the fiber-reinforced plastic molded articles according to Examples 1 to 4 and Comparative Examples 1 and 2. [Figure 3] 1 is a graph showing the proportion of PA6 in the fiber-reinforced plastic molded articles according to Examples 1 to 4 and Comparative Examples 1 and 2, and the results of heat resistance tests. [Figure 4] 4 is a graph in which the vertical axis (rate of change in thickness) of the graph in FIG. 3 is enlarged in the range of 100 to 160%. DETAILED DESCRIPTION OF THE INVENTION

[0021] Embodiments of the present invention will be described below with reference to the drawings. However, the embodiments described below are merely examples for embodying the technical concept of the present invention, and the present invention is not limited thereto. Furthermore, this specification in no way specifies the components set forth in the claims as components of the embodiments. The dimensions, materials, shapes, and relative positions of components described in the embodiments are not intended to limit the scope of the present invention, and are merely illustrative unless otherwise specified. The size and relative positions of components shown in the drawings may be exaggerated for clarity. Furthermore, in the following description, the same names and symbols indicate identical or similar components, and detailed descriptions will be omitted as appropriate. Furthermore, the elements constituting the present invention may be configured with the same components, so that one component serves multiple functions, or conversely, the functions of one component may be shared among multiple components.

[0022] Fiber-reinforced plastics made with conventional thermoplastic resins have the problem of inferior heat resistance compared to those made with thermosetting resins. In contrast, fiber-reinforced plastics with excellent heat resistance can be obtained by using resins known as super engineering plastics, such as PEI. One way to increase the strength of fiber-reinforced plastics made with such super engineering plastics is to increase the amount of reinforcing fibers. However, increasing the amount of reinforcing fibers makes it difficult for the resin to penetrate between the reinforcing fibers, which increases the likelihood of voids (air gaps) forming.

[0023] In contrast, the substrate for fiber-reinforced plastics, fiber-reinforced plastics, and methods for manufacturing the same according to the present embodiment can provide a substrate for fiber-reinforced plastics, fiber-reinforced plastics, and methods for manufacturing the same, in which the strength of fiber-reinforced plastics using super engineering plastics is increased without changing the amount of reinforcing fiber. [Embodiment 1]

[0024] A fiber-reinforced plastic substrate according to a first embodiment of the present invention includes reinforcing fibers and a matrix resin. The matrix resin includes a first matrix resin and a second matrix resin different from the first matrix resin. The first matrix resin is a super engineering plastic fiber. The second matrix resin is a thermoplastic engineering plastic fiber.

[0025] The volume ratio of the first matrix resin to the second matrix resin is set to 90:10 to 25:75, and more preferably 90:10 to 50:50. By using two matrix resin components in this way, a fiber-reinforced plastic with improved reinforcing effect can be realized without reducing heat resistance. (First matrix resin)

[0026] The super engineering plastic fiber of the first matrix resin is at least one of polyetherimide (PEI)-based fiber, polyphenylene sulfide (PPS)-based fiber, polyether ether ketone (PEEK)-based fiber, polyether ketone ketone (PEKK)-based fiber, polyethersulfone (PES)-based fiber, thermoplastic polyimide (TPI)-based fiber, polyvinylidene fluoride (PVDF)-based fiber, perfluoroalkoxyalkane (PFA)-based fiber, liquid crystal polymer (LCP)-based fiber, and polycarbonate (PC)-based fiber. (Second matrix resin)

[0027] On the other hand, the thermoplastic engineering plastic fibers of the second matrix resin are polyamide fibers. The melting point of the polyamide fibers is 170°C or higher. Preferably, the melting point of the polyamide fibers is 200°C to 270°C. This allows the melting point to be matched with the molding temperature of the first matrix resin, and further provides advantages such as being able to obtain the reinforcing effect of the second matrix resin while maintaining the heat resistance of the first matrix resin. (reinforced fiber)

[0028] The reinforcing fibers are any of carbon fibers, glass fibers, basalt fibers, silica fibers, Tyranno fibers, alumina fibers, and organic fibers. Aramid fibers are preferably used as the organic reinforcing fibers. The reinforcing fibers may also contain recycled fibers recycled from used fiber-reinforced plastic molded bodies. This reduces the environmental impact. The fiber length of the reinforcing fibers is preferably about 6 mm. (binder resin)

[0029] Furthermore, the substrate for fiber-reinforced plastics according to the first embodiment preferably contains a binder resin. A heat-and-moisture binder fiber can be suitably used as the binder resin. The heat-and-moisture binder fiber is preferably either a polyvinyl alcohol (PVA)-based fiber or an ethylene-vinyl alcohol copolymer (EVOH)-based fiber. This provides advantages such as ensuring the strength of the substrate for fiber-reinforced plastics during the manufacturing process without affecting the physical properties of the fiber-reinforced plastic molded article. (Fiber reinforced plastic molding)

[0030] A fiber-reinforced plastic molded article can be obtained by hot-press molding such a substrate for fiber-reinforced plastics. In other words, the substrate for fiber-reinforced plastics is a precursor for obtaining a fiber-reinforced plastic molded article. [Method of manufacturing a substrate for fiber-reinforced plastics]

[0031] Here, a method for manufacturing a fiber-reinforced plastic substrate is described. First, one of carbon fiber, glass fiber, basalt fiber, silica fiber, Tyranno fiber, alumina fiber, and organic fiber is prepared as reinforcing fibers. On the other hand, super engineering plastic fiber is prepared as a first matrix resin. On the other hand, thermoplastic engineering plastic fiber is prepared as a second matrix resin. The first matrix resin fiber and the second matrix resin fiber are prepared in a volume ratio of 90:10 to 25:75, respectively. On the other hand, moist heat binder fiber is prepared as a binder resin. These reinforcing fibers, super engineering plastic fiber, engineering plastic fiber, and moist heat binder fiber are blended and molded into a blended mat material. The thickness of the blended mat material after molding is preferably 0.05 mm to 3.0 mm. [Method of manufacturing fiber-reinforced plastic molded body]

[0032] The fiber-reinforced plastic molded article can be obtained by press-molding one or more sheets of the mixed mat material for fiber-reinforced plastics obtained by the above method, preferably at a temperature of 250°C to 300°C, which is the molding temperature for super-engineering plastics and engineering plastics. [Examples 1 to 4, Comparative Examples 1 and 2]

[0033] Next, fiber-reinforced plastic substrates according to the examples and comparative examples were produced, and their properties were measured and compared. Here, the fiber-reinforced plastic substrates according to Examples 1 to 4 and Comparative Examples 1 and 2 used 25 vol% carbon fibers with a fiber length of 6 mm as the reinforcing fibers and 5 vol% PVA fibers as the binder. These were mixed with a matrix resin to obtain a mixed mat material with a thickness of 0.1 mm after molding. For the matrix resins, PEI fibers were used as the first matrix resin and PA (nylon 6) fibers were used as the second matrix resin. The volume ratio of the first matrix resin to the second matrix resin was varied in Examples 1 to 4 and Comparative Examples 1 and 2. Specifically, the ratio was 100:0 in Comparative Example 1, 90:10 in Example 1, 75:25 in Example 2, 50:50 in Example 3, 25:75 in Example 4, and 0:100 in Comparative Example 2.

[0034] Ten sheets of the mixed mat material for fiber-reinforced plastic substrate obtained as described above were stacked and subjected to heat and pressure molding at a molding temperature of 250°C and 12 MPa. When the temperature dropped to 70°C, the laminate was removed to obtain a fiber-reinforced plastic molded body. The thickness [mm], density [g / cm3] of this fiber-reinforced plastic molded body were measured. 3The fiber-reinforced plastic molded articles were also evaluated through tensile tests, bending tests, and heat resistance tests, and the tensile strength [MPa], tensile modulus [GPa], and thickness change rate [%] due to the heat resistance test were measured. Thickness and density measurements were performed in accordance with JIS P 8118 (2014). Tensile strength and tensile modulus measurements were performed using 15 mm x 200 mm x 1 mm thick test specimens with a support distance of 110 mm and a test speed of 2 mm / min, in accordance with JIS K 7164 (2005). The thickness change rate due to the heat resistance test, which should normally be evaluated based on the strength after several hundred hours, was instead evaluated by an accelerated test in which a 15 mm x 100 mm x 1 mm thick test specimen was heated to 210°C in a constant-temperature oven for 20 minutes, and the thickness was measured at three points (the center and both ends) and averaged to calculate the average value using the following formula:

[0035] Thickness change rate [%] = (thickness after heating) / (thickness before heating) x 100

[0036] These results are shown in Table 1. Graphs showing the relationship between the proportion of PA6 and tensile strength in the fiber-reinforced plastic molded articles of Examples 1 to 4 and Comparative Examples 1 and 2 are shown in Fig. 1, graphs showing the relationship between the proportion of PA6 and tensile elasticity are shown in Fig. 2, graphs showing the relationship between the proportion of PA6 and heat resistance test results are shown in Fig. 3, and a graph in which the vertical axis (thickness change rate) of the graph in Fig. 3 is enlarged in the range of 100 to 160% is shown in Fig. 4. In Figs. 1 to 4, the theoretical values ​​based on the rule of mixture for the volume ratios of the first and second matrix resins are shown with dashed lines.

[0037] [Table 1]

[0038] The results in Figure 1 show that all Examples exhibited tensile strengths higher than the theoretical value of the mixture rule. That is, according to the mixture rule, tensile strength increases in proportion to the volume fraction of the second matrix resin, but in all Examples, values ​​higher than the theoretical value were obtained. Although the cause of this has not been determined, it is presumed that the matrix resin was not made uniform, and the addition of the second matrix resin (nylon 6) made it non-uniform, resulting in changes in the properties.

[0039] 2, all Examples showed tensile modulus values ​​higher than the theoretical value of the rule of mixture. According to the rule of mixture, tensile modulus increases in proportion to the volume fraction of the second matrix resin. However, all Examples showed values ​​higher than the theoretical value, demonstrating an improvement regardless of the amount of second matrix resin added. The average value for each Example was 121% of the value for Comparative Example 1, where no second matrix resin was added.

[0040] On the other hand, the results in Figure 3 show that, according to the theoretical value of the rule of mixture, increasing the ratio of the second matrix resin would result in a deterioration in heat resistance, volume expansion, and an increase in the thickness change rate. However, in all Examples, the thickness change rate was suppressed, confirming that heat resistance was exhibited regardless of the ratio of the second matrix resin. Specifically, as shown in Table 1, while the thickness change rate was nearly 600% in Comparative Example 2 (volume ratio in the matrix resin: 0:100), it was suppressed to approximately 150% or less in each Example. In particular, in Examples 1 to 3, it was suppressed to 140% or less.

[0041] As described above, it was confirmed that the tensile strength, tensile modulus, and heat resistance of each example were superior to the theoretical values ​​of the composite rule. Although the reason for this is not clear, it is presumed that by reinforcing the reinforcing fibers with the second matrix and surrounding them with the first matrix, it is possible to achieve both strength and heat resistance. [Industrial Applicability]

[0042] The substrate for fiber-reinforced plastic, the fiber-reinforced plastic, and the method for producing the same according to the present invention can be suitably used as exterior or structural materials for automobiles, trains, ships, aircraft, etc.

Claims

1. A substrate for fiber reinforced plastics, Reinforced fibers and As a matrix resin, a first matrix resin; a second matrix resin different from the first matrix resin; Including, the first matrix resin is a super engineering plastic fiber, the second matrix resin is a thermoplastic engineering plastic fiber; a volume ratio of the first matrix resin to the second matrix resin is 90:10 to 25:75; the super engineering plastic fiber of the first matrix resin is a polyetherimide fiber; the thermoplastic engineering plastic fibers of the second matrix resin are polyamide fibers; the reinforcing fibers are any one of carbon fibers, glass fibers, basalt fibers, silica fibers, Tyranno fibers, alumina fibers, and organic fibers; A test piece of 15 mm x 100 mm x 1 mm thick was heated in a thermostatic oven at 210°C for 20 minutes, and the thickness was measured at three points at the center and both ends, and the average value was calculated. Thickness change rate [%] = (thickness after heating) / (thickness before heating) × 100 The thickness change rate defined by the formula (1) is 140% or less.

2. The substrate for fiber reinforced plastic according to claim 1, A substrate for fiber-reinforced plastics, wherein the melting point of the polyamide fiber is 170°C or higher.

3. The substrate for fiber reinforced plastic according to claim 1 or 2, The polyamide fiber has a melting point of 200°C to 270°C.

4. The substrate for fiber reinforced plastics according to any one of claims 1 to 3, The substrate for fiber-reinforced plastics, wherein the polyamide fibers are either recycled polyamide resin fibers or biomass polyamide resin fibers.

5. The substrate for fiber reinforced plastics according to any one of claims 1 to 4, The substrate for fiber-reinforced plastics is characterized in that the organic fiber of the reinforcing fiber is an aramid fiber.

6. The substrate for fiber reinforced plastics according to any one of claims 1 to 5, The substrate for fiber-reinforced plastics, wherein the reinforcing fibers comprise recycled fibers.

7. The substrate for fiber reinforced plastics according to any one of claims 1 to 6, further comprising: Contains a binder resin, The substrate for fiber-reinforced plastics, wherein the binder resin is a heat-and-moisture binder fiber.

8. The substrate for fiber reinforced plastic according to claim 7, The substrate for fiber-reinforced plastics, wherein the heat-and-moisture binder fiber is either a polyvinyl alcohol fiber or an ethylene-vinyl alcohol copolymer fiber.

9. A fiber-reinforced plastic molded body obtained by hot-press molding the fiber-reinforced plastic substrate according to any one of claims 1 to 8.

10. A method for producing a substrate for fiber reinforced plastics, As reinforcing fibers, carbon fiber, glass fiber, basalt fiber, silica fiber, Tyranno fiber, alumina fiber, or organic fiber, As a matrix resin, The first matrix resin is a super engineering plastic fiber; a second matrix resin, which contains a thermoplastic engineering plastic fiber and a second matrix resin in a volume ratio of 90:10 to 25:75; As a binder resin, a heat-and-moisture binder fiber and a step of molding the mixture into a mixed matte material; Including, the super engineering plastic fiber of the first matrix resin is a polyetherimide fiber; the thermoplastic engineering plastic fibers of the second matrix resin are polyamide fibers; the reinforcing fibers are any one of carbon fibers, glass fibers, basalt fibers, silica fibers, Tyranno fibers, alumina fibers, and organic fibers; A test piece of 15 mm x 100 mm x 1 mm thick was heated in a thermostatic oven at 210°C for 20 minutes, and the thickness was measured at three points at the center and both ends, and the average value was calculated. Thickness change rate [%] = (thickness after heating) / (thickness before heating) × 100 The method for producing a substrate for fiber reinforced plastics, wherein the thickness change rate defined by the above formula (1) is 140% or less.

11. The method for producing a substrate for fiber reinforced plastic according to claim 10, The method for producing a substrate for fiber-reinforced plastics, wherein the thickness of the mixed mat material after molding is 0.05 mm to 3.0 mm.

12. A method for producing a fiber-reinforced plastic molded article, comprising a step of press-molding one or more sheets of a mixed mat material for a fiber-reinforced plastic substrate produced by the method for producing a fiber-reinforced plastic substrate according to claim 10 or 11.

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