Manufacturing method for composite molded products

Abstract

This method for producing a composite molded article comprises: a step for preparing a plurality of UD tapes, each of which comprises a tape-like base material sheet that is formed of a thermoplastic resin, and reinforcing fibers that are impregnated into the base material sheet in such a manner that the reinforcing fibers are oriented in the same direction; and a step in which the prepared plurality of UD tapes are continuously introduced into a mold, while being stacked upon each other, and subsequently heated, thereby obtaining a composite molded article that has a predetermined cross-sectional shape. A UD tape which has a thickness of 20 μm to 80 μm, a width of 0.5 mm to 10 mm and a weight per square meter of the reinforcing fibers of 30 g / m2 to 95 g / m2 is used for the above-described UD tapes.

Description

[Technical Field]

[0001] The present invention relates to a method for producing a composite molded article in which reinforcing fibers are contained in a thermoplastic resin. [Background technology]

[0002] One method for producing such a composite molded product is known from Patent Document 1. The manufacturing method described in Patent Document 1 includes the steps of tearing a sheet-like prepreg (UD sheet) made of a thermoplastic resin containing reinforcing fibers into tape-like pieces, and introducing the resulting tape-like prepregs into a mold (the molding die of a pultrusion device) while arranging them in a cylindrical shape, and heating them. This results in a cylindrical composite molded product with a uniform ring-shaped cross section.

[0003] In Patent Document 1, a ring-shaped cavity (molding space) defined in a mold is divided into multiple regions in the circumferential direction, and tape-like prepregs are introduced one by one into each of these regions. For this reason, Patent Document 1 requires that the thickness of each tape-like prepreg be set to a relatively large value equal to or greater than the thickness of the molded product. However, if the thickness of each prepreg is large, the stiffness of each prepreg increases (shape conformability decreases), making it difficult to mold molded products with small cross-sectional sizes or complex cross-sectional shapes. Another problem is that voids (cavities) are likely to occur inside the molded product. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 05-269831 Summary of the Invention

[0005] The present invention has been made in view of the above circumstances, and has as its object to produce a composite molded article having a high degree of freedom in shape and few voids.

[0006] In order to solve the above problems, the method for producing a composite molded product of the present invention includes a first step of preparing a plurality of UD tapes, each of which includes a tape-shaped base sheet made of a thermoplastic resin and reinforcing fibers impregnated into the base sheet in a state where the reinforcing fibers are oriented in the same direction, and a second step of molding a composite molded product having a predetermined cross-sectional shape by stacking the plurality of prepared UD tapes and continuously introducing the stacked UD tapes into a mold and heating the stacked UD tapes, wherein the UD tapes have a thickness of 20 μm to 80 μm, a width of 0.5 mm to 10 mm, and a basis weight of the reinforcing fibers of 30 g / m. 2 More than 95g / m 2 It is characterized by using the following UD tape.

[0007] According to the manufacturing method of the present invention, a composite molded article having a high degree of freedom in shape and few voids can be manufactured. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a flowchart showing a schematic procedure of a method for manufacturing a composite molded product according to a first embodiment of the present invention. [Figure 2] FIG. 1 is a diagram showing a schematic configuration of an apparatus for manufacturing a UD sheet. [Figure 3] FIG. 10 is a diagram showing how a UD tape is cut out from a UD sheet. [Figure 4] FIG. 1 is a schematic cross-sectional view of a UD tape. [Figure 5] FIG. 1 is a diagram showing a schematic configuration of an apparatus for manufacturing a composite molded product from a UD tape. [Figure 6] FIG. 2 is a cross-sectional view showing the structure of a molding die and a composite molded product therein. [Figure 7] FIG. 5 is a view corresponding to FIG. 4, showing a modification of the first embodiment. [Figure 8] 1 is a table showing the characteristics of examples of the present invention and comparative examples. [Figure 9] FIG. 7 is a view corresponding to FIG. 6 for explaining a second embodiment of the present invention. [Figure 10] FIG. 10 is a cross-sectional view showing the structure of a composite molded product manufactured in a third embodiment of the present invention. [Figure 11] FIG. 10 is a diagram showing a schematic configuration of a manufacturing apparatus used in the third embodiment. [Figure 12] FIG. 2 is a cross-sectional view showing the structure of a molding die of the manufacturing apparatus. DETAILED DESCRIPTION OF THE INVENTION

[0009] (1) First embodiment FIG. 1 is a flowchart showing the outline of the steps of a method for manufacturing a composite molded article 20 (FIGS. 5 and 6) according to a first embodiment of the present invention. In this embodiment, the composite molded article 20 is a molded article made of a thermoplastic resin containing reinforcing fibers, and is manufactured by the steps (S1 to S3) shown in FIG. 1. That is, the composite molded article 20 of this embodiment is manufactured by a procedure including step S1 of molding a UD sheet 1 (FIG. 2), step S2 of cutting out a plurality of UD tapes 10 (FIG. 3) from the UD sheet 1, and step S3 of subjecting the plurality of UD tapes 10 to pultrusion molding to obtain the composite molded article 20 (FIGS. 5 and 6). Details of each step are as follows:

[0010] [UD sheet molding] As shown in Fig. 2, step S1 is a sheet forming step in which a UD sheet 1 is formed from a base sheet 2 and reinforcing fibers 3. Specifically, in this sheet forming step S1, a fiber reinforced plastic sheet (FRTP sheet) including a base sheet 2 made of a thermoplastic resin and a large number of reinforcing fibers 3 impregnated on both sides of the base sheet 2 while being oriented in the same direction is formed into the UD sheet 1.

[0011] Carbon fibers, glass fibers, aramid fibers, ceramic fibers, etc. can be used as the reinforcing fibers 3. Among them, carbon fibers are advantageous in improving the strength and corrosion resistance of the molded product. As the carbon fibers, it is preferable to use PAN (polyacrylonitrile)-based carbon fibers, which have particularly high strength.

[0012] The base sheet 2 is a sheet having a certain width and thickness, and is formed, for example, by extruding a thermoplastic resin into a sheet shape.

[0013] Examples of thermoplastic resins that are the material of the base sheet 2, i.e., the matrix resin of the UD sheet 1, include polyamide (particularly PA6, PA9T, PA12, and PA66), polyethylene, polypropylene, polyphenylene sulfide, polyolefin, polyester, polyacetal, polycarbonate, acrylic resin, acrylonitrile-butadiene-styrene copolymer (ABS), polyamideimide, polysulfone, polyphenylsulfone, polyetherimide, polyethersulfone, polyetheretherketone, polyetherketoneketone, polyimide, polyarylate, fluororesin, liquid crystal polymer, and thermoplastic epoxy resin. Alternatively, a polymer alloy, which is a mixture of two or more of these thermoplastic resins, may be used as the material of the base sheet 2.

[0014] The UD sheet 1 can be manufactured using, for example, a sheet manufacturing apparatus 50 shown in Fig. 2. This sheet manufacturing apparatus 50 is an apparatus that continuously manufactures the UD sheet 1 from a fiber bundle 3', which is a bundle of reinforcing fibers, and a thermoplastic base sheet 2.

[0015] Specifically, the sheet manufacturing apparatus 50 includes multiple pairs (here, two pairs) of heating rollers 51 arranged vertically, multiple pairs (here, two pairs) of cooling rollers 52 arranged vertically below the heating rollers 51, a pair of endless belts 54 looped between the heating rollers 51 and the cooling rollers 52, a pair of pull-out rollers 55 arranged below the endless belts 54, and a winding bobbin 56 arranged below the pull-out rollers 55.

[0016] On both sides of the uppermost heating roller 51, there are provided spreading mechanisms (not shown) that spread the fiber bundle 3' into a band shape. These spreading mechanisms continuously spread the fiber bundle 3', thereby making it possible to form a large number of continuous reinforcing fibers 3 spread into a thin band shape. Any mechanism capable of performing this process can be used as the spreading mechanism, and various mechanisms can be used, such as a mechanism that spreads the fiber bundle by beating it, a mechanism that spreads the fiber bundle by blowing air on it, or a mechanism that spreads the fiber bundle by applying ultrasonic waves to it.

[0017] 2, the fiber-spreading mechanism has a mechanism for supplying the spread reinforcing fibers 3 to one side of the base sheet 2, and a mechanism for supplying the spread reinforcing fibers 3 to the other side of the base sheet 2. The former mechanism is provided to introduce the reinforcing fibers 3 between one side of the base sheet 2 and the heating roller 51 in contact with that side, and the latter mechanism is provided to introduce the reinforcing fibers 3 between the other side of the base sheet 2 and the heating roller 51 in contact with that side.

[0018] The heating roller 51 is a high-temperature roller heated by an electric heater or a heating medium, etc. The heating roller 51 heats the base sheet 2 and the reinforcing fibers 3 introduced on both sides thereof while sandwiching them from both sides via the endless belt 54, thereby continuously impregnating the base sheet 2 with the reinforcing fibers 3. As a result, the base sheet 2 is impregnated with the reinforcing fibers 3 in a state where they are aligned in one direction (the vertical direction in FIG. 2 ).

[0019] The cooling roller 52 is a low-temperature roller cooled by a cooling medium or the like. The cooling roller 52 cools the base sheet 2 impregnated with the reinforcing fibers 3 while sandwiching it from both sides via the endless belt 54, thereby fixing the reinforcing fibers 3 to the base sheet 2. In this way, a UD sheet 1 in which the base sheet 2 (matrix resin) and the reinforcing fibers 3 are integrated is formed.

[0020] The pull-out roller 55 is a roller that applies tension to the formed UD sheet 1 and pulls it downward.

[0021] The winding bobbin 56 is a core material for winding up the UD sheet 1. The bobbin 56 is driven to rotate by a drive source such as a motor, and sequentially winds up the UD sheet 1 drawn out by the drawing roller 55, thereby gathering the UD sheet 1 into a roll.

[0022] [UD tape molding] Step S2 is a tape cutting step in which UD tapes 10 are cut out from the UD sheet 1 formed in the sheet forming step S1. In this tape cutting step S2, as shown in Fig. 3, a plurality of UD tapes 10 are cut out from the UD sheet 1 by forming a plurality of slits Q1 extending in the longitudinal direction in the UD sheet 1. Specifically, in the tape cutting step S2, while feeding the UD sheet 1 in the longitudinal direction, cutting is performed from position P1 along the feeding path, thereby forming a large number of slits Q1 extending in the longitudinal direction in the UD sheet 1. As a result, the UD sheet 1 is divided into small pieces in the width direction, and a plurality of UD tapes 10 each having a relatively small width and elongated in the longitudinal direction are formed.

[0023] The above-described incisions Q1 can be formed (cut) in the UD sheet 1 using, for example, a cutting device including multiple blades arranged at equal intervals across the width of the UD sheet 1. When using a cutting device including such equally spaced blades, it becomes possible to collectively form UD tapes 10 of the same width from the UD sheet 1. Note that a cutting device in which the spacing between adjacent blades varies depending on the combination of blades may also be used, and in this way, UD tapes 10 of various different widths can be formed from the UD sheet 1.

[0024] As described above, the original sheet from which the UD tape 10 is cut, i.e., the UD sheet 1, is a thermoplastic fiber-reinforced resin sheet in which a base sheet 2 is impregnated with reinforcing fibers 3. Therefore, each UD tape 10 cut out from the UD sheet 1 also has a base sheet 2 and reinforcing fibers 3. That is, as shown in the schematic cross-sectional view of Fig. 4, the UD tape 10 has a base sheet 2 made of a thermoplastic resin and reinforcing fibers 3 impregnated into the base sheet 2 while being oriented in the same direction.

[0025] More specifically, in this embodiment, the UD tape 10 is a semi-impregnated UD tape in which the reinforcing fibers 3 are partially impregnated on both sides of the base sheet 2. In other words, the UD tape 10 in this embodiment has a tape-shaped base sheet 2 and the reinforcing fibers 3 impregnated only in the surface layers on both sides of the base sheet 2. In this case, most of the reinforcing fibers 3 in the UD tape 10 are impregnated into the base sheet 2 in a state where they are partially exposed to the outside of the base sheet 2, and are not completely impregnated into the interior of the base sheet 2. In the sheet forming step S1 described above, the UD sheet 1 is formed so as to obtain a UD tape 10 having such a structure. That is, when the UD sheet 1 is formed using the sheet manufacturing apparatus 50 (FIG. 2), the pressure and heating temperature of the heating roller 51 (FIG. 2) are adjusted so that the reinforcing fibers 3 are impregnated only in the surface layers on both sides of the base sheet 2.

[0026] As shown in Figure 4, the thickness and width of the UD tape 10 are designated as t and w, respectively. The thickness t of the UD tape 10, i.e., the total thickness t including the base sheet 2 and the reinforcing fibers 3 on both sides thereof, is set to 20 μm to 80 μm, preferably 25 μm to 60 μm, and more preferably 30 μm to 55 μm. The width w of the UD tape 10 is set to 0.5 mm to 10 mm, preferably 1 mm to 5 mm, and more preferably 1.5 mm to 3 mm.

[0027] The weight of the reinforcing fibers 3 in the UD tape 10, that is, the weight of the reinforcing fibers 3 impregnated into the base sheet 2 per unit area, is 30 g / m 2 More than 95g / m 2 Less than 40 g / m 2 More than 90g / m 2 or less, more preferably 45 g / m 2 More than 85g / m 2 It is set as follows:

[0028] Table 1 below summarizes the specifications (thickness, width, and basis weight) of the UD tape 10 described above.

[0029] [Table 1]

[0030] The above-mentioned sheet forming step S1 and tape cutting step S2 are carried out in a manner that allows a UD tape 10 having the specifications shown in Table 1 to be obtained. That is, in the sheet forming step S1, a sheet having a basis weight (30 to 95 g / m) equivalent to the basis weight of the reinforcing fibers 3 in the UD tape 10 shown in Table 1 is cut out. 2 The density and other properties of the reinforcing fibers 3 supplied from the spreading mechanism to both sides of the base sheet 2 are adjusted so that a UD sheet 1 having a width w (0.5 to 10 mm) shown in Table 1 is obtained. In the sheet forming process S1, the thickness of the base sheet 2 and the fiber diameter of the reinforcing fibers 3 are adjusted so that a UD sheet 1 having a thickness (20 to 80 μm) equivalent to the thickness t of the UD tape 10 shown in Table 1 is obtained. In the tape cutting process S2, the pitch of the incisions Q1 (FIG. 3) formed in the UD sheet 1 is adjusted so that a plurality of UD tapes 10 having a width w (0.5 to 10 mm) shown in Table 1 is cut out from the UD sheet 1.

[0031] [Molding of composite molded products] Step S3 is a drawing step in which a composite molded product 20 is continuously formed from the plurality of UD tapes 10 formed in the tape cutting step S2 using a drawing device 60 shown in Fig. 5. Specifically, in this embodiment, in the drawing step S3, a round bar-shaped composite molded product 20 having a constant circular cross section along the axial direction is formed by continuous molding using the drawing device 60.

[0032] The drawing device 60 includes a tape feeder 61, a molding die 62, a cooler 63, a take-up machine 64, and a winder 65. The tape feeder 61 is a device that aggregates and feeds multiple UD tapes 10 downstream. The molding die 62 is a mold that receives the UD tape 10 fed from the tape feeder 61 and applies heat and pressure to it, transforming the received UD tape 10 into a composite molded article 20 with a circular cross section and discharging it downstream. The cooler 63 is a device that cools the composite molded article 20 discharged from the molding die 62. The take-up machine 64 is a device that takes up the composite molded article 20 discharged from the cooler 63 and sends it further downstream. The winder 65 is a device that winds up the composite molded article 20 fed from the take-up machine 64 into a roll.

[0033] The tape feed machine 61 includes a plurality of feed rollers 71 around which the UD tape 10 is wound, a plurality of guide rolls 72 that change the direction of the UD tape 10 fed by the rotation of the feed rollers 71 so that the UD tape 10 heads toward a desired position downstream, and a plurality of guides 73 that regulate the feed path of each UD tape 10 so that the plurality of UD tapes 10 gradually gather downstream of the group of guide rolls 72. The plurality of UD tapes 10 are gathered vertically and horizontally as they pass through all the guides 73, and are continuously introduced into the forming die 62 in a stacked state.

[0034] 6, the molding die 62 is a mold divided into two parts, an upper part and an lower part, having therein a cavity C1 having a circular cross section corresponding to the shape of the composite molded product 20. That is, the molding die 62 includes an upper part 81 and a lower part 82 that is placed below the upper part 81 in close contact with each other, and a semicircular recess is formed on each of the opposing surfaces of the upper part 81 and the lower part 82. The recesses of the upper part 81 and the lower part 82 are combined to form the cavity C1 having a circular cross section.

[0035] The molding die 62 has a built-in heating device. This heating device heats the UD tape 10 introduced into the cavity C1 of the molding die 62, softening the UD tape 10. The softened UD tape 10 is pressurized and deformed in the cavity C1, changing into a composite molded product 20 with a circular cross section corresponding to the cavity C1. The cross-sectional area of ​​this composite molded product 20 can be set in various ways, but it is preferably set to, for example, at least twice the cross-sectional area of ​​the UD tape 10. This is to ensure that the effects of the manufacturing method of this embodiment (e.g., suppression of voids, improvement of mechanical properties, etc.) described below are accurately obtained.

[0036] The cooler 63 is disposed adjacent to the downstream side of the forming die 62. The cooler 63 may have any structure as long as it can cool the high-temperature composite molded article 20 discharged from the forming die 62, but it may be, for example, a low-temperature mold having a cavity similar to that of the forming die 62 and into which a refrigerant such as cooling water is introduced. In this case, the forming die 62 and the cooler 63 may be configured as a single mold.

[0037] 6 is an enlarged view of a portion of the cross section of the composite molded product 20. As shown in this enlarged view, multiple UD tapes 10 are adhered to and fixed to one another in a stacked state inside the composite molded product 20. In other words, the composite molded product 20 is a fiber-reinforced composite molded product with a circular cross section formed by integrating multiple UD tapes 10, each including a base sheet 2 and reinforcing fibers 3, in a layered manner within the cavity C1.

[0038] The take-off machine 64 includes multiple pairs of rollers 91 and a pair of endless belts 92 that are arranged in a vertical direction and are wound around the rollers 91. The rollers 91 rotate while sandwiching the composite molded article 20 from above and below via the endless belts 92, thereby sending the composite molded article 20 discharged from the molding die 62 further downstream.

[0039] The winding machine 65 includes a rotatable winding roller 95. The winding roller 95 rotates in a direction to wind up the composite molded article 20, and sequentially winds up the composite molded article 20 delivered from the take-up machine 64 into a roll.

[0040] In the drawing step S3, the drawing device 60 having the above-described configuration is used to continuously form the composite molded article 20 having a circular cross section from the UD tape 10.

[0041] [Action and effect] As described above, in this embodiment, a plurality of UD tapes 10 each including a tape-shaped base sheet 2 and reinforcing fibers 3 impregnated in the base sheet 2 are prepared, and the prepared UD tapes 10 are stacked and continuously introduced into the molding die 62, where they are heated, to form a composite molded article 20 having a certain cross-sectional shape (here, a circular cross-section). In this way, this embodiment, in which the composite molded article 20 is continuously molded (pultrusion molded) from the UD tapes 10, has the advantage of being able to increase the degree of freedom in the shape of the composite molded article 20 while suppressing the generation of voids (cavities) inside the composite molded article 20.

[0042] Specifically, in this embodiment, the thickness t, width w, and basis weight of the reinforcing fibers 3 of the UD tape 10 are set as shown in Table 1 above, so that the UD tape 10 is endowed with appropriate flexibility while the reinforcing effect of the reinforcing fibers 3 can be sufficiently enhanced. This reduces the proportion of voids (cavities) generated inside the composite molded article 20, and sufficiently improves the mechanical properties (tensile strength, bending strength, etc.) of the composite molded article 20.

[0043] For example, the thickness t of the UD tape 10 is set to 80 μm or less (preferably 60 μm or less, more preferably 55 μm or less), which provides the UD tape 10 with appropriate flexibility and allows the UD tape 10 to be smoothly introduced into the molding die 62 while being appropriately deformed. This, combined with the width w of the UD tape 10 being set to 10 mm or less (preferably 5 mm or less, more preferably 3 mm or less), has the effect of preventing clogging of the UD tape 10 inside the molding die 62, making it possible to introduce a large number of UD tapes 10 into the molding die 62 in a sufficiently dense state. Therefore, even when molding a composite molded article 20 having a small cross-sectional size or a complex cross-sectional shape, the material can be filled at a high filling rate into the cavity C1 of the molding die 62 corresponding to the shape of the composite molded article 20, thereby producing a high-quality composite molded article 20 with few voids.

[0044] In addition, while the thickness of the UD tape 10 is reduced as described above, the weight of the reinforcing fiber 3 is 30 g / m 2 or more (preferably 40 g / m 2 More preferably, 45 g / m 2 Since the above conditions are ensured, the reinforcing fibers 3 can be dispersed relatively uniformly in the resin softened during molding, and the mechanical properties of the composite molded product 20 can be improved efficiently.

[0045] As shown in each example (FIG. 8) described later, according to the method of this embodiment for manufacturing a composite molded article 20 using a UD tape 10 having the specifications shown in Table 1, the proportion of voids (cavities) in the composite molded article 20, i.e., the void ratio, can be reduced to 15% or less. This, combined with the above-mentioned effect of uniformly dispersing the reinforcing fibers 3, makes it possible to sufficiently improve the mechanical strength of the composite molded article 20. The void ratio refers to the proportion of the cross-sectional area of ​​voids to the total cross-sectional area of ​​the composite molded article 20.

[0046] Furthermore, in this embodiment, a semi-impregnated UD tape in which the base sheet 2 is partially impregnated with the reinforcing fibers 3 is used as the UD tape 10 (see FIG. 4 ). This allows for greater flexibility of the UD tape 10 than when a fully impregnated UD tape in which the base sheet 2 is completely impregnated with the reinforcing fibers 3 is used (see FIG. 7 , which will be described later). This allows for a higher filling rate of the material filling the cavity C1 when the UD tape 10 is introduced into the molding die 62, and sufficiently reduces the proportion of voids that may occur in the composite molded product 20. Note that even when a semi-impregnated UD tape 10 is used as in this embodiment, the reinforcing fibers 3 are completely impregnated with the resin when the UD tape 10 is introduced into the molding die 62, so there is no particular problem with the quality of the composite molded product 20.

[0047] [Variations] In the first embodiment, the composite molded product 20 in the shape of a round rod having a circular cross section is molded from the UD tape 10, but the shape of the composite molded product that can be molded from the UD tape 10 is not limited to this, and composite molded products of various shapes can be molded from the UD tape 10. For example, it is possible to mold a composite molded product in the shape of a flat plate having a flat rectangular cross section.

[0048] In the first embodiment, a semi-impregnated UD tape 10 ( FIG. 4 ) in which the reinforcing fibers 3 are partially impregnated into the base sheet 2 was used. However, a fully impregnated UD tape 10A as shown in FIG. 7 can also be used. This UD tape 10A is a UD tape in which the reinforcing fibers 3 are completely impregnated into the base sheet 2, with substantially all of the reinforcing fibers 3 impregnated within the base sheet 2 so that almost none of the reinforcing fibers 3 are exposed outside the base sheet 2. When a composite molded product is formed using such a fully impregnated UD tape 10A, the reinforcing fibers 3 are less likely to come off the base sheet 2 before the UD tape 10A is introduced into the molding die 62, thereby sufficiently enhancing the reinforcing effect of the reinforcing fibers 3 on the composite molded product. The fact that either a semi-impregnated or fully impregnated UD tape can be used is the same in the second and third embodiments described below.

[0049] In the first embodiment described above, a winding machine 65 that winds up the composite molded product and assembles it into a roll is provided at the most downstream part of the drawing device 60 (see Figure 5), but instead of this winding machine 65, a cutting machine that cuts the composite molded product to a fixed length may be provided.

[0050] [Example] The results of actually manufacturing composite molded products using the manufacturing method of the first embodiment or its modified example described above are shown in Fig. 8 as Examples 1 to 8. That is, under various conditions with different specifications (thickness, width, basis weight) of the UD tape 10, flat plate-shaped or round bar-shaped composite molded products were manufactured according to the manufacturing method shown in Figs. 1 to 5, and the obtained results are referred to as Examples 1 to 8, respectively. The manufacturing conditions for each Example are as follows:

[0051] (Manufacturing conditions) (i) Flat plate-shaped molded products (Examples 1 to 7) Dimensions: Thickness x Width = 1mm x 10mm Matrix resin: PA6 Reinforced fiber: PAN-based carbon fiber Heating temperature: 250℃ Cooling temperature: 30℃ Line speed: 0.1m / min (ii) Round rod-shaped molded product (Example 8) Dimensions: 1.1mm diameter Matrix resin: PA6 Reinforced fiber: PAN-based carbon fiber Heating temperature: 280℃ Cooling temperature: 30℃ Line speed: 0.3m / min

[0052] In the above manufacturing conditions, the heating temperature refers to the heating temperature in the forming die 62 shown in Fig. 5, and the cooling temperature refers to the cooling temperature in the cooler 63 shown in Fig. 5. The linear speed refers to the speed at which the composite molded product is taken up by the take-up machine 64, in other words, the drawing speed at the forming die 62.

[0053] 8 also shows Comparative Examples 1 to 6. Comparative Examples 1 to 6 are the results obtained by molding flat composite molded products under the same manufacturing conditions as Examples 1 to 7 using UD tapes 10 whose thickness, width, or basis weight was outside the ranges in Table 1.

[0054] As shown in Figure 8, in Examples 1 to 8, where the specifications of the UD tape 10 were within the ranges listed in Table 1, the void fraction was kept below 15%. In contrast, in Comparative Examples 1 to 6, where the specifications of the UD tape 10 were outside the ranges listed in Table 1, the void fraction exceeded 15% or the required shape of the composite molded product (here, a flat plate shape with a cross section of 1 x 10 mm) could not be obtained. In Figure 8, cases where the required shape could not be obtained are marked as "unmoldable," and the causes are indicated as (I) to (III). Specifically, unmoldable (I) is a case where molding failure occurred due to tape breakage of the UD tape 10 during molding. Unmoldable (II) is a case where molding failure occurred due to resin outflow, where the resin separated from the reinforcing fibers and flowed out first. Unmoldable (III) is a case where molding failure occurred due to insufficient resin.

[0055] From a comparison between the above-mentioned Examples 1 to 8 and Comparative Examples 1 to 6, it is clear that there is an advantage in molding a composite molded product using the UD tape 10 having the thickness, width, and basis weight specified in Table 1.

[0056] (2) Second embodiment In the first embodiment, the solid composite molded product 20 is molded from the UD tape 10, but it is also possible to mold a hollow composite molded product instead of a solid one, an example of which will be described as a second embodiment.

[0057] FIG. 9 is a cross-sectional view showing the structure of a molding die 102 used in the second embodiment. As shown in this figure, in the second embodiment, a composite molded product 20A having a rectangular cross section is continuously molded from a UD tape 10 by pultrusion molding using the molding die 102. The molding die 102 includes an upper mold 111 and a lower mold 112 that are stacked one on top of the other, and a core mold 113 disposed between them. A cavity C2 having a rectangular cross section is formed inside the molding die 102, surrounded by these three molds 111-113. The UD tape 10 is the same as that used in the first embodiment, i.e., a UD tape having the thickness, width, and basis weight specified in Table 1 above. The UD tape 10 is fed into the molding die 102 from the tape feeder 61 shown in FIG. 5, introduced into the cavity C2 while being stacked, and then pulled out by the take-up machine 64. This results in a composite molded product 20A having a rectangular cross section corresponding to the shape of the cavity C2 being continuously molded.

[0058] As shown in FIG. 9, each corner of the composite molded product 20A is rounded. However, the radius of each rounding is relatively small, with the minimum radius set to 0.1 mm. Generally, the filling rate of material tends to decrease at such small-diameter corners. For this reason, the rectangular tubular composite molded product 20A has a problem in that it is difficult to ensure its molding quality. However, in the second embodiment (see Table 1), in which a flexible UD tape 10 with a relatively small thickness t and width w is used, even the rectangular tubular composite molded product 20A can be molded satisfactorily. In other words, the use of the flexible UD tape 10 facilitates the material to reach every corner of the cavity C2, allowing the material to be filled at a sufficient filling rate even at each small-diameter corner, resulting in a high-quality rectangular tubular composite molded product 20A.

[0059] (3) Third embodiment In the first and second embodiments, a composite molded product is formed by introducing a UD tape into a molding die, but a composite molded product with a two-layer structure can also be formed by introducing molten resin around the UD tape introduced into the molding die. An example of this will be described as the third embodiment.

[0060] FIG. 10 is a cross-sectional view showing the structure of a composite molded article 20B manufactured by the manufacturing method of the third embodiment. As shown in this figure, the composite molded article 20B includes a composite portion 21 and a surface portion 22. The composite portion 21 is a layer in which UD tapes 10 having the specifications shown in Table 1 are laminated. In other words, the composite portion 21 is made of a fiber-reinforced resin in which a base sheet 2 (matrix resin) made of a thermoplastic resin is mixed with reinforcing fibers 3. The surface portion 22 is a thermoplastic resin layer formed around the composite portion 21. Unlike the composite portion 21, the surface portion 22 does not contain reinforcing fibers. The composite portion 21 and the surface portion 22 are integrated with each other by the surface portion 22 being in close contact with the outer peripheral surface of the composite portion 21. The material of the surface portion 22 may be the same as or different from the matrix resin of the composite portion 21.

[0061] In the third embodiment, the composite molded product 20B is a flat plate-like molded product having a constant rectangular cross section along the axial direction. That is, the composite molded product 20B has a composite portion 21 having a flat rectangular cross section and a square cylindrical surface portion 22 surrounding the composite portion 21.

[0062] The composite molded product 20B is manufactured using a drawing device 160 shown in FIG. 11. As shown in this figure, the drawing device 160 includes a tape feeder 161, a molding die 162, an extruder 166, a cooler 163, a take-up machine 164, and a cutter 167. The tape feeder 161 is similar to the tape feeder 61 of the first embodiment (FIG. 5) and feeds a plurality of UD tapes 10 downstream while collecting them. The molding die 162 is a mold that receives the UD tape 10 fed from the tape feeder 161 and applies heat and pressure to the UD tape 10. The extruder 166 is a device that injects molten resin into the molding die 162. The cooler 163 is similar to the cooler 63 of the first embodiment and cools the composite molded product 20B discharged from the molding die 162. The take-up machine 164 is similar to the take-up machine 64 of the first embodiment, and takes up the composite molded product 20B discharged from the cooler 163 and sends it further downstream. The cutting machine 167 is a device including a cutter 167a that cuts the composite molded product 20B sent out from the take-up machine 164 to a predetermined length.

[0063] 12, the molding die 62 is a mold divided into two parts, an upper part and a lower part, and has therein a cavity C3 with a rectangular cross section corresponding to the shape of the composite molded product 20B. That is, the molding die 162 includes an upper mold 181 and a lower mold 182 that is placed below the upper mold 181 in close contact with the upper part, and the cavity C3 with a rectangular cross section is formed between the upper mold 181 and the lower mold 182.

[0064] The cross-sectional shape of the cavity C3 changes midway through the molding die 62. That is, the cavity C3 includes an upstream cavity C3a and a downstream cavity C3b that is slightly larger than the upstream cavity C3a. The upstream cavity C3a is a space with a rectangular cross section that corresponds to the composite portion 21 of the composite molded product 20B. The downstream cavity C3b is a relatively large space with a rectangular cross section that corresponds to the surface portion 22 of the composite molded product 20B, and is formed continuously downstream from the upstream cavity C3a.

[0065] 12, the extruder 166 includes a cylinder 166a connected to the upper mold 181 so as to communicate with the downstream cavity C3b, and a screw 166b arranged inside the cylinder 166a. The screw 166b melts and kneads the resin introduced into the cylinder 166a while pumping it into the lower cavity C3b.

[0066] A plurality of UD tapes 10 fed from the tape feeder 161 (FIG. 11) are introduced into the upstream cavity C3a and integrated through heating and pressurization within the upstream cavity C3a. As a result, a composite section 21 having a rectangular cross section corresponding to the upstream cavity C3a is formed. Then, molten resin discharged from the extruder 166 is supplied around the formed composite section 21. That is, by discharging the molten resin from the extruder 166 into the downstream cavity C3b, the gap between the outer peripheral surface of the composite section 21 introduced into the downstream cavity C3b and the inner peripheral surface of the downstream cavity C3b is filled with the molten resin. As a result, a surface section 22 (FIG. 10) is formed around the composite section 21, and a two-layered composite molded product 20B is molded by integrating the two.

[0067] In the third embodiment, as shown in Fig. 10, an example was described in which a two-layer composite molded product 20B was molded, which includes a fiber-reinforced resin composite portion 21, which is a mixture of a thermoplastic resin substrate sheet 2 (matrix resin) and reinforcing fibers 3, and a resin surface portion 22 (containing no reinforcing fibers) that covers the composite portion 21. However, it is also possible to mold a multilayer composite molded product having a different structure. For example, it is possible to mold a two-layer composite molded product in which a portion of the periphery of the fiber-reinforced resin composite portion is covered with a resin surface portion, or a three-layer composite molded product in which the periphery of the resin surface portion is further covered with fiber-reinforced resin. Alternatively, a two-layer composite molded product may be molded in which at least a portion of the periphery of a resin core material is covered with fiber-reinforced resin.

[0068] (4) Summary The above-described embodiments mainly include the following inventions.

[0069] A method for producing a composite molded product according to one aspect of the present invention includes a first step of preparing a plurality of UD tapes each comprising a tape-shaped base sheet made of a thermoplastic resin and reinforcing fibers impregnated in the base sheet in a state where the reinforcing fibers are oriented in the same direction, and a second step of forming a composite molded product having a predetermined cross-sectional shape by stacking the prepared UD tapes and continuously introducing them into a mold and heating them. The UD tapes have a thickness of 20 μm to 80 μm, a width of 0.5 mm to 10 mm, and a basis weight of the reinforcing fibers of 30 g / m. 2 More than 95g / m 2 The following UD tapes are used:

[0070] According to the present invention, the UD tape has a thickness of 80 μm or less, which provides the UD tape with adequate flexibility and allows it to be smoothly introduced into a mold while being appropriately deformed. This, combined with the UD tape width of 10 mm or less, prevents clogging of the UD tape in the mold, allowing multiple UD tapes to be introduced into the mold in a sufficiently dense state. Therefore, even when molding a composite molded product with a small cross-sectional size or a complex cross-sectional shape, the material can be filled into the mold cavity corresponding to the shape of the composite molded product at a high filling rate, resulting in a high-quality composite molded product with few voids.

[0071] In addition, while the thickness of the UD tape is reduced as mentioned above, the weight of the reinforcing fiber is 30 g / m 2 Since the above is ensured, the reinforcing fibers can be dispersed relatively uniformly in the resin softened during molding, and the mechanical properties of the composite molded product can be efficiently improved.

[0072] Preferably, the UD tape has a thickness of 25 μm or more and 60 μm or less, a width of 1 mm or more and 5 mm or less, and a weight of the reinforcing fibers of 40 g / m 2 More than 90g / m 2 Use the following UD tape.

[0073] In this way, the above-mentioned effects can be further enhanced.

[0074] More preferably, the UD tape has a thickness of 30 μm or more and 55 μm or less, a width of 1.5 mm or more and 3 mm or less, and a basis weight of the reinforcing fibers of 45 g / m 2 More than 85g / m 2 Use the following UD tape.

[0075] In this way, the above-mentioned effects can be further enhanced.

[0076] Preferably, the UD tape used is a semi-impregnated type UD tape in which the base sheet is partially impregnated with the reinforcing fibers.

[0077] In this way, the use of semi-impregnated UD tape can increase the flexibility of the UD tape compared to the use of fully impregnated UD tape, in which the reinforcing fibers are completely impregnated into the base sheet. This allows for a higher filling rate of the material that fills the cavity when the UD tape is introduced into the mold, and significantly reduces the rate of voids that may occur in the composite molded product.

[0078] Preferably, in the second step, a composite molded article having a cross-sectional area at least twice as large as the cross-sectional area of ​​the UD tape is molded.

[0079] In this way, the above-mentioned effects (such as suppression of voids and improvement of mechanical properties) can be obtained accurately.

[0080] The manufacturing method of the present invention may further include a third step of supplying a molten resin around the UD tape introduced into the mold.

[0081] In this way, it is possible to manufacture a composite molded product with a two-layer structure including a composite part in which UD tape is laminated and a resin surface part formed around it.

Claims

1. A first step of preparing a plurality of UD tapes each including a tape-shaped base sheet made of a thermoplastic resin and reinforcing fibers impregnated into the base sheet in a state where the reinforcing fibers are oriented in the same direction; a second step of successively stacking and introducing the prepared UD tapes into a mold and heating the laminated tapes to form a composite molded product having a predetermined cross-sectional shape; The UD tape has a thickness of 20 μm or more and 80 μm or less, a width of 0.5 mm or more and 10 mm or less, and a basis weight of the reinforcing fibers of 30 g / m ２ 95g / m or more ２ A method for producing a composite molded product, characterized by using the following UD tape:

2. The method for producing a composite molded product according to claim 1, The UD tape has a thickness of 25 μm or more and 60 μm or less, a width of 1 mm or more and 5 mm or less, and a basis weight of the reinforcing fibers of 40 g / m ２ 90g / m or more ２ A method for producing a composite molded product, characterized by using the following UD tape:

3. The method for producing a composite molded product according to claim 2, The UD tape has a thickness of 30 μm or more and 55 μm or less, a width of 1.5 mm or more and 3 mm or less, and a basis weight of the reinforcing fibers of 45 g / m ２ 85g / m or more ２ A method for producing a composite molded product, characterized by using the following UD tape:

4. In the method for producing a composite molded product according to any one of claims 1 to 3, A method for producing a composite molded product, characterized in that the UD tape is a semi-impregnated type UD tape in which the base sheet is partially impregnated with the reinforcing fibers.

5. The method for producing a composite molded product according to any one of claims 1 to 4, The method for producing a composite molded product, wherein the second step is to mold a composite molded product having a cross-sectional area at least twice as large as the cross-sectional area of ​​the UD tape.

6. The method for producing a composite molded product according to any one of claims 1 to 5, A method for manufacturing a composite molded product, further comprising a third step of supplying molten resin around the UD tape introduced into the mold.

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