Prepreg, multilayer body, molded article, flange, and prepreg production method

Abstract

Provided are: a new prepreg using a mixed fiber yarn; a multilayer body; a molded article; a flange; and a prepreg production method. A prepreg according to the present disclosure comprises: a base material; a mixed fiber yarn provided on the substrate; and a shape-retaining yarn that retains the mixed fiber yarn on the base material. The mixed fiber yarn includes thermoplastic resin fibers and reinforcing fiber bundles, and is regularly arranged radially around an arbitrary point on the base material. The greatest inter-reinforcing fiber bundle distance between adjacent reinforcing fiber bundles in the prepreg satisfies formula (A). Inter-reinforcing fiber bundle distance (mm) = [thickness (tex) of reinforcing fiber bundles] / [10 × reinforcing fiber bundle density (g / cm3) × molded article thickness (mm) × reinforcing fiber volume (vol%) in molded article with respect to molded article volume]

Description

Prepreg, multilayer body, molded article, flange, and method for manufacturing prepreg

[0001] The present invention relates to a prepreg, a multilayer body, a molded article, a flange, and a method for producing a prepreg.

[0002] In recent years, fiber-reinforced thermoplastic resin materials (FRPs) composed of fibers and thermoplastic resins have attracted attention (see Patent Documents 1 to 4). FRPs are widely used in a variety of applications due to their light weight and high strength. A typical example of FRP is a fiber-reinforced thermoplastic resin material in which fibers are impregnated into a thermoplastic resin. Such FRPs are typically used as prepregs, which are formed by heating and bonding multiple sheets of fiber-reinforced thermoplastic resin material in which fibers are impregnated into a thermoplastic resin. These prepregs are further heated and processed into a shape appropriate for the desired application. The present applicant has also disclosed a blended fiber yarn whose fiber components are composed of continuous thermoplastic resin fibers and continuous reinforcing fibers. Furthermore, stitching (embroidery) using such blended fiber yarns has also been investigated (see Patent Document 5). This type of stitching is called tailored fiber placement (TFP).

[0003] JP 2011-207198 A JP 2014-169411 A JP 2010-017934 A JP 2014-173196 A WO 2016 / 159340

[0004] As mentioned above, tailored fiber placement processing using prepregs and commingled yarns has been studied, but the scope of its application is expanding. For example, there is also a demand for prepregs for molding cylindrical molded products. In this situation, an object of the present invention is to provide a new prepreg using commingled yarns, as well as a method for manufacturing a multilayer body, a molded product, a flange, and a prepreg.

[0005] Under these circumstances, the above-mentioned problem has been solved by the following means: [1] A prepreg comprising a substrate, a mixed fiber yarn provided on the substrate, and a shape-retaining yarn that retains the shape of the mixed fiber yarn on the substrate, wherein the mixed fiber yarn comprises thermoplastic resin fibers and reinforcing fiber bundles and is regularly arranged radially around an arbitrary point on the substrate as a center, wherein the distance between adjacent reinforcing fiber bundles in the prepreg, the widest distance between reinforcing fiber bundles, satisfies the following formula (A): Formula (A) Distance between reinforcing fiber bundles (mm) = [thickness of reinforcing fiber bundle (tex)] / [10 × density of reinforcing fiber bundle (g / cm ３) × thickness (mm) of molded article × volume of reinforcing fibers in the molded article relative to the volume of the molded article (volume %)] (In formula (A), the molded article is obtained by press-molding the prepreg at a temperature of the melting point of the thermoplastic resin resin contained in the thermoplastic resin fiber + 40°C and a pressure of 2 MPa for 15 minutes. The thickness of the molded article is 0.05 to 1 mm.) [2] The prepreg according to [1], wherein the reinforcing fibers contained in the mixed yarn are arranged at an angle of more than 0° and not more than 10° with respect to a line passing through the center of the substrate. [3] The prepreg according to [1], wherein the reinforcing fibers contained in the mixed yarn are arranged at an angle of more than 10° and less than 90° with respect to a line passing through the center of the substrate. [4] The prepreg according to any one of [1] to [3], wherein the substrate is a resin film and the shape-retaining yarn is a thermoplastic resin yarn, and the difference in melting point between the substrate, the thermoplastic resin fiber, and the thermoplastic resin yarn is within 10°C. [5] A prepreg comprising a substrate, a mixed yarn continuously provided on the substrate, and a shape-retaining yarn that retains the shape of the mixed yarn on the substrate, wherein the mixed yarn comprises a thermoplastic resin fiber and a reinforcing fiber bundle, and is regularly arranged radially around an arbitrary point on the substrate. [6] The prepreg according to any one of [1] to [5], wherein the mixed yarn is a single yarn. [7] The prepreg according to any one of [1] to [6], wherein the prepreg is a fiber placement prepreg. [8] The prepreg according to any one of [1] to [7], wherein circular stitching centered on the center of the substrate is provided by a shape-retaining yarn. [9] A multilayer body having two or more plies of the prepreg according to any one of [1] to [8], wherein the centers of the two or more plies of prepregs are on the same axis.

[10] The multilayer body according to [9], wherein one or more plies of the prepreg are arranged at an angle of more than 0° and not more than 10° relative to a line passing through the center of the substrate, and one or more other plies of the prepreg are arranged at an angle of more than 10° and less than 90° relative to a line passing through the center of the substrate.

[11] A molded product obtained by heat processing the multilayer body according to [9] or

[10] .

[12] A flange obtained by heat processing the multilayer body according to [9] or

[10] .

[13] A method for producing a prepreg, comprising: subjecting a mixed yarn to tailored fiber placement processing on a substrate using a shape-retaining yarn so that the mixed yarn is regularly arranged radially around an arbitrary point on the substrate as a center; wherein the mixed yarn contains the thermoplastic resin fiber and reinforcing fiber.

[0006] The present invention makes it possible to provide a new prepreg using a mixed fiber yarn, as well as a multilayer body, a molded article, a flange, and a method for manufacturing a prepreg.

[0007] 7 is a schematic diagram of a first example of a prepreg of this embodiment. FIG. 1 is a partially enlarged view of FIG. 1. A photograph of a prepreg produced according to the schematic diagram of FIG. 1 is shown. A partially enlarged view of FIG. 1. A schematic diagram showing a state in which a mixed yarn is shape-retained by a shape-retaining yarn. A partially enlarged view of FIG. 1. A schematic diagram of a second example of a prepreg of this embodiment. FIG. 7 is a photograph (plan view) of a prepreg produced according to the schematic diagram of FIG. 7. A photograph (bottom view) of a prepreg produced according to the schematic diagram of FIG. 7. A photograph (front view) of a prepreg produced according to the schematic diagram of FIG. 7. A photograph (back view) of a prepreg produced according to the schematic diagram of FIG. 7. A photograph (left side view) of a prepreg produced according to the schematic diagram of FIG. 7. A photograph (right side view) of a prepreg produced according to the schematic diagram of FIG. 7. A partially enlarged view of FIG. 8. A schematic diagram showing the layer structure of a multilayer body of this embodiment. A diagram showing an example of image processing in a method for measuring the degree of dispersion. A diagram showing the results of an investigation into the relationship between the widest distance between reinforcing fibers and the thickness of a molded product, carried out in Example 3.

[0008] Hereinafter, a mode for carrying out the present invention (hereinafter simply referred to as "the present embodiment") will be described in detail. Note that the following present embodiment is an example for explaining the present invention, and the present invention is not limited to this embodiment. Note that in this specification, the term "to" is used to mean that the numerical values ​​before and after it are included as the upper and lower limits. "A to B" means A or more and B or less. Furthermore, any combination of the upper and lower limit values ​​of numerical values ​​in this specification can be cited as an example of this embodiment. In this specification, various physical property values ​​and characteristic values ​​are those at 23°C unless otherwise specified.

[0009] In this specification, unless otherwise specified, the number average molecular weight is a value measured by the following method. The number average molecular weight (Mn) is measured using gel permeation chromatography (GPC) measurement, using a standard polymethyl methacrylate (PMMA) equivalent value. Two columns packed with a styrene polymer are used as the packing material, and hexafluoroisopropanol (HFIP) with a sodium trifluoroacetate concentration of 2 mmol / L is used as the solvent. The resin concentration is 0.02 mass%, the column temperature is 40 ° C, the flow rate is 0.3 mL / min, and the measurement is performed using a refractive index detector (RI). In addition, the calibration curve is measured by dissolving six levels of PMMA in HFIP.

[0010] In this specification, the melting point (Tm) is measured using a differential scanning calorimeter (DSC), using a sample amount of approximately 1 mg, flowing nitrogen as the atmospheric gas at 30 mL / min, and heating at a rate of 10°C / min from room temperature to a temperature above the expected melting point, and the melting point (Tm) is determined from the peak top temperature of the endothermic peak observed when the sample is melted. The unit is °C. The differential scanning calorimeter (DSC) used is a "DSC-7020" manufactured by Hitachi High-Tech Science Corporation.

[0011] In this specification, the term "step" includes not only independent steps but also steps that are not clearly distinguishable from other steps, as long as the intended effect of the step is achieved. All steps described in this specification can be performed in any suitable order unless otherwise specified in the specification or clearly contradicted by the context. If the measurement methods, etc. described in the standards shown in this specification change from year to year, they will be based on the standards in effect as of January 1, 2024, unless otherwise specified. If the measurement methods, etc. described in the standards shown in this specification are discontinued as of January 1, 2024, they will be based on the standards in effect at the time of discontinuation. The drawings may not be to scale or the like.

[0012] Hereinafter, an embodiment of the present invention will be described in detail, but the description of the constituent elements described below is one example of an embodiment of the present invention and is not limited to these contents. The prepreg of this embodiment includes a substrate, a mixed fiber yarn provided on the substrate, and a shape-retaining yarn that retains the shape of the mixed fiber yarn on the substrate, the mixed fiber yarn including thermoplastic resin fiber and reinforcing fiber bundles, and is a prepreg that is regularly arranged radially around an arbitrary point on the substrate as a center, and is characterized in that the widest distance between adjacent reinforcing fiber bundles in the prepreg satisfies the following formula (A): Formula (A) Distance between reinforcing fiber bundles (mm) = [thickness of reinforcing fiber bundle (tex)] / [10 × density of reinforcing fiber bundle (g / cm ３ ) × thickness of molded article (mm) × volume of reinforcing fibers in the molded article relative to the volume of the molded article (volume %)] (In formula (A), the molded article is a molded article obtained by press-molding the prepreg at a temperature of the melting point of the thermoplastic resin contained in the thermoplastic resin fiber + 40°C and a pressure of 2 MPa for 15 minutes. The thickness of the molded article is 0.05 to 1 mm.)

[0013] By arranging the mixed yarns radially and regularly around an arbitrary point on the substrate, carbon fibers can be distributed in multiple directions, thereby reducing stress. Conventionally, unidirectional tapes (UD tapes) have been layered in place of the prepreg having the above-described shape. However, with UD tapes, the thickness of the overlapping portions of the tapes increases. Furthermore, the ends of the reinforcing fibers are cut off, resulting in a weakened strength of the resulting molded article. In this embodiment, the mixed yarns are radially and regularly arranged, eliminating thickness variations due to overlapping of the reinforcing fibers and further reducing the number of reinforcing fiber ends. Furthermore, the thickness of the resulting molded article can be made more uniform, resulting in a molded article with superior strength. In particular, by laminating prepregs of this embodiment with different mixed yarn arrangements, the reinforcing fibers are distributed in more directions in the resulting molded article, resulting in a molded article with superior strength. Furthermore, when the mixed yarns are radially and regularly arranged, the proportion of the mixed yarn decreases toward the radial outside, resulting in resin pools forming in the molded article. On the other hand, shortening the distance between the mixed yarns (especially the distance between the reinforcing fibers) increases the thickness. When using a laminate of multiple plies of prepregs, it is desirable that each prepreg is thin. Furthermore, the prepreg of this embodiment is less likely to have uneven thickness, and is therefore excellent for forming a multilayer body by laminating multiple plies of prepregs. The configuration of this embodiment will be described below with reference to the drawings. It goes without saying that this embodiment is not limited to the form shown in the drawings.

[0014] FIG. 1 is a schematic diagram showing a first example of a prepreg of this embodiment, in which 1 indicates a substrate, 2 indicates a mixed fiber yarn provided on the substrate, and 3 indicates the center of the substrate. The shape-retaining yarn is not shown. Also, reference numerals 4, 5, and 6 in FIG. 1 indicate circular stitching centered at center 3 on the substrate. Note that the same reference numerals are used throughout the drawings to indicate the same components unless otherwise specified. The substrate 1 is not particularly limited as long as it can retain the shape of the mixed fiber yarn 2 on the substrate 1 with the shape-retaining yarn, and a wide variety of known substrates can be used. An example of the substrate 1 is a resin film. Details of the resin film, mixed fiber yarn, and shape-retaining yarn will be described later. The shape of the mixed fiber yarn 2 is preferably retained by stitching it onto the surface of the substrate 1. An example of this stitching method is tailored fiber placement processing. In this embodiment, the use of mixed fiber yarn 2 enables tailored fiber placement processing, which allows the mixed fiber yarn 2 to be regularly arranged radially from any point on the substrate 1 as center 3. That is, the prepreg of this embodiment is preferably a fiber placement prepreg.

[0015] In the prepreg of this embodiment, the mixed yarns 2 are regularly arranged radially with any one point on the base material 1 as the center 3. The position of the center 3 is not particularly determined as long as it is a position where the mixed yarns 2 can be arranged. From the viewpoint of saving materials, the base material 1 is preferably a regular polygon or a circle, and the center 3 is preferably located at the same position as the center of gravity of the regular polygon that is the base material or the center of the circle. In the prepreg of this embodiment, the mixed yarns 2 are regularly arranged radially with the center 3 of the base material 1 as the center. "Radial" means a shape that spreads in all directions from the center 3. However, it is not essential that the stitching of the mixed yarns 2 spread outward from the center 3. "Regular" means that a pattern made of the mixed yarns 2 is formed with a certain regularity. It goes without saying that the terms "radial" and "regular" do not require geometric accuracy and include errors within the normal range in the technical field of the present invention. In addition, as shown in Figure 6, etc., it may also include areas where the mixed yarns are not regularly arranged radially, such as the shape-retaining start point and shape-retaining end point of the mixed yarns. Hereinafter, angles etc. will be interpreted in the same way.

[0016] In one example of the arrangement of the mixed yarn 2 in this embodiment, as shown in Figure 1, the reinforcing fibers contained in the mixed yarn 2 are arranged at an angle of more than 0° and not more than 10° with respect to a line passing through the center 3 on the substrate 1. That is, Figure 2 is a partial enlarged view of Figure 1, and the angle α in Figure 2 is more than 0° and not more than 10° with respect to the line passing through the center 3 on the substrate 1. More specifically, in Figure 2, the angle α formed by the line 7 passing through the center 3 on the substrate 1 and the arrangement direction 8 of the mixed yarn 2 is an angle of more than 0° and not more than 10°. Such an angle is also called a roving angle in fiber placement prepregs.

[0017] The prepreg in FIG. 1 comprises a substrate 1, a mixed yarn 2 continuously provided on the substrate 1, and a shape-retaining yarn (not shown) that retains the shape of the mixed yarn 2 on the substrate 1. The mixed yarn 2 preferably comprises a thermoplastic resin fiber and a reinforcing fiber bundle, and is regularly arranged radially from a center 3 of an arbitrary point on the substrate 1. Here, the mixed yarn 2 is preferably continuous on the substrate 1. The continuous length of the mixed yarn 2 is preferably 10 cm or more, and it is also preferable that the entire prepreg in one ply is continuous, i.e., it is a single mixed yarn. By using a single mixed yarn in this way, productivity when molding a preform by TFP tends to be further improved. Furthermore, the strength of the resulting molded product tends to be further improved.

[0018] FIG. 3 shows a photograph of the prepreg prepared according to the schematic diagram of FIG.

[0019] On the other hand, in the prepreg of the present embodiment, the widest distance between adjacent reinforcing fiber bundles in the prepreg satisfies the following formula (A): Distance between reinforcing fiber bundles (mm) = [thickness of reinforcing fiber bundle (tex)] / [10 × density of reinforcing fiber bundle (g / cm ３ ) × thickness of molded article (mm) × volume of reinforcing fibers in the molded article relative to the volume of the molded article (volume %)] (In formula (A), the molded article is a molded article obtained by press-molding the prepreg at a temperature of the melting point of the thermoplastic resin contained in the thermoplastic resin fiber + 40°C and a pressure of 2 MPa for 15 minutes. The thickness of the molded article is 0.05 to 1 mm.)

[0020] That is, when the mixed yarns are arranged regularly in a radial pattern, there are regions on the surface of the substrate where there are many mixed yarns and regions where there are few mixed yarns. For example, in Figure 3, the distance between the mixed yarns increases from the center outward. Therefore, when the prepreg of this embodiment is processed by heating and pressure, the resin in the mixed yarns spreads, but the reinforcing fibers do not spread as much as the resin, so resin pools form and the strength of these areas becomes weaker than other areas. In addition, thickness unevenness occurs when the prepreg is processed by heat. Therefore, in this embodiment, the prepreg is configured to satisfy the above formula (A). Here, the thickness of the reinforcing fiber bundles (tex, i.e., the mass (g) of the reinforcing fiber bundles per 1 m) and the density of the reinforcing fiber bundles (g / cm) in the prepreg state are considered. ３ ), the distance between reinforcing fibers (mm), and the thickness (mm) of a molded article obtained by press-molding the prepreg at a temperature of the melting point of the thermoplastic resin fiber + 40°C and a pressure of 2 MPa for 15 minutes. By satisfying formula (A), a molded article without resin pools can be obtained.

[0021] In formula (A), the widest distance between the reinforcing fiber bundles is preferably 1.5 mm or more, more preferably 1.7 mm or more, even more preferably 1.9 mm or more, still more preferably 2.1 mm or more, still more preferably 2.5 mm or more, and preferably 5.0 mm or less, even more preferably 4.5 mm or less, still more preferably 4.2 mm or less, still more preferably 3.8 mm or less, still more preferably 3.5 mm or less.

[0022] In formula (A), the volume of the reinforcing fibers in the molded article relative to the volume of the molded article is preferably 35% by volume or more, more preferably 40% by volume or more, and even more preferably 45% by volume or more. By setting it to the lower limit or more, the mechanical strength of the obtained molded article tends to be further improved. The volume of the reinforcing fibers in the molded article relative to the volume of the molded article is preferably 65% ​​by volume or less, more preferably 60% by volume or less, even more preferably 55% by volume or less, even more preferably 58% by volume or less, and even more preferably 53% by volume or less. Only one type of reinforcing fiber bundle may be used, or two or more types may be used. When two or more types are used, it is preferable that the total amount is within the above range.

[0023] In formula (A), the thickness of the molded article is 0.05 mm or more, preferably 0.07 mm or more, more preferably 0.1 mm or more, even more preferably 0.13 mm or more, still more preferably 0.15 mm or more, and 1 mm or less, preferably 0.5 mm or less, even more preferably 0.45 mm or less, still more preferably 0.4 mm or less. Note that formula (A) is an index determined to increase the strength of a molded article obtained from the prepreg of this embodiment, and it goes without saying that it is not essential that a molded article formed from the prepreg of this embodiment satisfy the above thickness.

[0024] On the other hand, the widest distance between adjacent reinforcing fiber bundles in a prepreg is, for example, the widest part of the distance between lines 7 and 8 in Fig. 2 (i.e., part 9 in Fig. 4). An enlarged view of this is shown in Fig. 4. Furthermore, the widest distance between adjacent reinforcing fiber bundles in a prepreg in a second example described later is, for example, the part indicated by arrow 12 in Fig. 14.

[0025] The thickness and density of the reinforcing fiber bundles, as well as the distance between the reinforcing fiber bundles, refer to the actual values ​​in the prepreg before press molding. The distance between the reinforcing fiber bundles is an actually measured value.

[0026] In this embodiment, the mixed yarn is shape-retained by a shape-retaining yarn. The shape-retaining yarn is, for example, a yarn that retains the shape of the mixed yarn 2 on a substrate (not shown) as shown in Figure 5. In the prepreg before heating and pressing, the shape-retaining yarn 10 retains the shape of the mixed yarn 2. The shape of the mixed yarn 2 is preferably maintained by the shape-retaining yarn 10 through fiber placement prepreg processing. Details of the shape-retaining yarn will be described later.

[0027] In the prepreg of this embodiment, it is preferable that at least one circular stitching (4, 5, 6 in Figures 1 and 2) centered on the center 3 on the base material 1 is provided using a shape-retaining yarn. By providing such stitching 4, 5, 6, the prepreg can be easily cut. More specifically, the circular stitching 4 centered on the center 3 on the base material 1 is used as a hole for passing a central axis when stacking multiple plies of prepreg. In other words, by providing the circular stitching 4, the circular stitching 4 acts as a perforation. As a result, when a central axis is passed through the prepreg, the portion of the base material 1 inside the circular stitching 4 is easily cut from the prepreg. In addition, multiple plies of prepreg can be stacked with high precision. More specifically, this will be explained using Figure 6. Figure 6 shows an enlarged view of the vicinity of the center 3 in Figure 1. As shown in Figure 6, the stitching 4 is formed so as to surround the periphery of the center 3 in Figure 1. Reference numeral 11 in Figure 6 denotes the shape-retaining start point 11 of the mixed yarn 2. It is usually preferable that the circular stitching 4 is provided inside the mixed yarn 2 which is regularly arranged radially and formed by the mixed yarn 2. Furthermore, when the stitching 4 is provided, it is preferable that the shape-retaining start point 11 of the mixed yarn 2 is provided outside the circular stitching 4 (opposite the center). With this configuration, even if the inner part (substrate) of the circular stitching 4 before heat and pressure processing is cut, the mixed yarn 2 is less likely to peel off from the substrate 1. Therefore, it is preferable that no material other than the substrate 1 exists inside the circular stitching 4. Similarly, it is preferable that the shape-retaining end point of the mixed yarn 2 is provided outside the circular stitching 4.

[0028] In this embodiment, it is also preferable that circular stitching 5 is provided in a portion closer to the side farther from the center 3 of the prepreg (the end of the prepreg). The circular stitching 5 is a portion that is cut before or after the heat processing of the preform, and serves as a marker and also serves to facilitate cutting like a perforation. The circular stitching 5 is usually provided on the mixed yarn 2 of the prepreg, in a portion closer to the end. For example, it is preferable that the circular stitching 5 is provided at a position 0.1 to 10 from the end of the mixed yarn 2, when the distance from the end to the center of the mixed yarn 2 is 100.

[0029] In this embodiment, it is preferable that circular stitching 6 is also provided in a portion closer to the center 3 than the circular stitching 5. The circular stitching 6 is also a portion to be cut before or after the heat processing of the preform, and serves as a marker for the cut, and also serves to facilitate cutting like a perforation. The circular stitching 6 is usually provided on the mixed yarn 2 of the prepreg, in a portion closer to the center 3. For example, when the distance from the center 3 to the end of the mixed yarn 2 is taken as 100, the circular stitching 6 is preferably provided at a position 0.1 to 10 from the center. The diameter of the circular stitching 5 is, for example, 160 to 300 mm, and the diameter of the circular stitching 6 is, for example, 50 to 150 mm. In addition, it is preferable that the difference in diameter between the circular stitching 5 and the circular stitching 6 is 50 to 150 mm.

[0030] The presence of the circular stitchings 5 ​​and 6 makes it possible to easily form cylindrical or ring-shaped molded articles such as flanges. For example, when a cylindrical molded article is formed by stacking multiple plies of the prepreg of this embodiment, it is preferable that the stitching 5 is located on the outside of the cylindrical molded article and the stitching 6 is located on the inside of the cylinder. In this case, it is preferable that the central axis of the cylinder coincides with the center 3. These details will be described later.

[0031] In the prepreg of this embodiment, it is also possible to further stitch mixed yarns in areas where resin pools are likely to form. By using such a configuration, thickness unevenness of the obtained prepreg can be effectively suppressed.

[0032] Next, the resin film used as the substrate will be described. The resin film used in this embodiment is preferably a thermoplastic resin film, and more preferably a crystalline thermoplastic resin film. A resin film typically comprises 30 to 100% by mass of resin (preferably a thermoplastic resin, more preferably a crystalline thermoplastic resin), preferably 50 to 100% by mass of resin, more preferably 80 to 100% by mass of resin, and even more preferably 90 to 100% by mass of resin. Examples of thermoplastic resins that can be used include polyolefin resins such as polyethylene and polypropylene, polyester resins such as polyamide resins, polyethylene terephthalate and polybutylene terephthalate, polycarbonate resins, polyoxymethylene resins, polyether ketone, polyether ether ketone, polyether ketone ketone, polyether ether ketone ketone, polyether sulfone resins, polyether sulfide resins, thermoplastic polyetherimides, thermoplastic polyamideimides, wholly aromatic polyimides, and semi-aromatic polyimides, and the like. A polyamide resin is preferred. The type of polyamide resin used in this embodiment is not particularly limited, and may be an aliphatic polyamide resin or a semi-aromatic polyamide resin, but is more preferably a semi-aromatic polyamide resin.

[0033] Examples of aliphatic polyamide resins include polyamide 4, polyamide 46, polyamide 6, polyamide 66, polyamide 666, polyamide 610, polyamide 11, and polyamide 12. Polyamide 6, polyamide 66, and polyamide 666 are preferred, with polyamide 66 being more preferred. As described above, the polyamide resin used in this embodiment preferably contains a semi-aromatic polyamide resin. For example, it is more preferred that 90% by mass or more of the polyamide resin contained in the resin film is a semi-aromatic polyamide resin. Here, a semi-aromatic polyamide resin refers to a polyamide resin composed of diamine-derived structural units and dicarboxylic acid-derived structural units, in which 20 to 80 mol % (preferably 30 to 80 mol %, more preferably 40 to 70 mol %) of the total structural units of the diamine-derived structural units and the dicarboxylic acid-derived structural units contain aromatic rings.

[0034] Examples of semi-aromatic polyamide resins include terephthalic acid-based polyamide resins (polyamide 6T, polyamide 9T, polyamide 10T) and xylylenediamine-based polyamide resins, which will be described later.

[0035] The polyamide resin used in this embodiment may be a recycled polyamide resin product (including recovered products, material recycled products, chemical recycled products, etc.), a rejected product, or scrap material generated when molding a molded product from a resin composition.

[0036] In this embodiment, a polyamide resin containing diamine-derived structural units and dicarboxylic acid-derived structural units, in which 70 mol% or more of the diamine-derived structural units are derived from xylylenediamine (hereinafter sometimes referred to as a "xylylenediamine-based polyamide resin") is preferred.

[0037] The diamine-derived structural units of the xylylenediamine-based polyamide resin are more preferably 75 mol% or more, even more preferably 80 mol% or more, even more preferably 90 mol% or more, still more preferably 95 mol% or more, and particularly preferably 99 mol% or more, of xylylenediamine (preferably paraxylylenediamine and / or metaxylylenediamine).

[0038] The xylylenediamine is preferably paraxylylenediamine and / or metaxylylenediamine. The xylylenediamine preferably contains 0 to 100 mol % metaxylylenediamine and 100 to 0 mol % paraxylylenediamine (provided that the total of metaxylylenediamine and paraxylylenediamine does not exceed 100 mol %), more preferably 10 to 90 mol % metaxylylenediamine and 90 to 10 mol % paraxylylenediamine, even more preferably 20 to 90 mol % metaxylylenediamine and 80 to 10 mol % paraxylylenediamine, still more preferably 40 to 90 mol % metaxylylenediamine and 60 to 10 mol % paraxylylenediamine, and even more preferably 60 to 80 mol % metaxylylenediamine and 40 to 20 mol % paraxylylenediamine. In the xylylenediamine-based polyamide resin, the total of the constitutional units derived from paraxylylenediamine and the constitutional units derived from metaxylylenediamine preferably accounts for 80 mol % or more, more preferably 85 mol % or more, even more preferably 90 mol % or more, still more preferably 95 mol % or more, still more preferably 98 mol % or more, and still more preferably 99 mol % or more of the constitutional units derived from diamine. The upper limit of the total of the constitutional units derived from paraxylylenediamine and the constitutional units derived from metaxylylenediamine is 100 mol %.

[0039] Diamines other than metaxylylenediamine and paraxylylenediamine that can be used as raw diamine components for xylylenediamine-based polyamide resins include aliphatic diamines such as tetramethylenediamine, pentamethylenediamine, 2-methylpentanediamine, hexamethylenediamine, heptamethylenediamine, octamethylenediamine, nonamethylenediamine, decamethylenediamine, dodecamethylenediamine, 2,2,4-trimethyl-hexamethylenediamine, and 2,4,4-trimethylhexamethylenediamine; 1,3-bis( Examples of the diamine include alicyclic diamines such as bis(aminomethyl)cyclohexane, 1,4-bis(aminomethyl)cyclohexane, 1,3-diaminocyclohexane, 1,4-diaminocyclohexane, bis(4-aminocyclohexyl)methane, 2,2-bis(4-aminocyclohexyl)propane, bis(aminomethyl)decalin, and bis(aminomethyl)tricyclodecane; and diamines having an aromatic ring such as bis(4-aminophenyl)ether, paraphenylenediamine, and bis(aminomethyl)naphthalene, and these can be used alone or in combination of two or more.

[0040] On the other hand, the dicarboxylic acid-derived constituent units of the xylylenediamine-based polyamide resin are preferably 70 mol% or more, more preferably 75 mol% or more, even more preferably 80 mol% or more, still more preferably 90 mol% or more, even more preferably 95 mol% or more, and particularly preferably 99 mol% or more, of which the dicarboxylic acid-derived constituent units are preferably derived from an α,ω-linear aliphatic dicarboxylic acid having 4 to 20 carbon atoms (preferably adipic acid).

[0041] Examples of α,ω-linear aliphatic dicarboxylic acids having 4 to 20 carbon atoms that are preferably used as the raw dicarboxylic acid component of the xylylenediamine-based polyamide resin include aliphatic dicarboxylic acids such as succinic acid, glutaric acid, adipic acid, azelaic acid, sebacic acid, undecanedioic acid, and 1,12-dodecanedioic acid. These can be used alone or in combination of two or more. Among these, at least one of adipic acid, sebacic acid, and 1,12-dodecanedioic acid is preferred, as the melting point of the polyamide resin falls within a range suitable for molding and processing. Adipic acid and / or sebacic acid is more preferred, and sebacic acid is even more preferred.

[0042] Examples of dicarboxylic acid components other than those mentioned above include phthalic acid compounds such as isophthalic acid, terephthalic acid, and orthophthalic acid, and isomers of naphthalenedicarboxylic acid such as 1,2-naphthalenedicarboxylic acid, 1,3-naphthalenedicarboxylic acid, 1,4-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, 1,6-naphthalenedicarboxylic acid, 1,7-naphthalenedicarboxylic acid, 1,8-naphthalenedicarboxylic acid, 2,3-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, and 2,7-naphthalenedicarboxylic acid, and these can be used alone or in combination of two or more.

[0043] Although the xylylenediamine-based polyamide resin is primarily composed of diamine-derived structural units and dicarboxylic acid-derived structural units, other structural units are not completely excluded. It goes without saying that the resin may contain structural units derived from lactams such as ε-caprolactam and laurolactam, and aliphatic aminocarboxylic acids such as aminocaproic acid and aminoundecanoic acid. Here, "major component" refers to the structural units constituting the xylylenediamine-based polyamide resin in which the combined number of diamine-derived structural units and dicarboxylic acid-derived structural units is the largest among all structural units. In this embodiment, the combined total of the diamine-derived structural units and dicarboxylic acid-derived structural units in the xylylenediamine-based polyamide resin preferably accounts for 90% by mass or more of all structural units, more preferably 95% by mass or more, even more preferably 97% by mass or more, and even more preferably 99% by mass or more.

[0044] It is also preferable to use a polyamide resin produced using biomass raw materials (biomass polyamide resin) as the xylylenediamine-based polyamide resin. The use of biomass polyamide resin can reduce the environmental impact. Bioadipic acid can be used as the biomass raw material in the xylylenediamine-based polyamide resin. Mass balance certified (ISCC PLUS) adipic acid can also be used. Mass balance certification means that the amount of renewable raw materials or bio-based raw materials used at each factory or production facility, and the amount of products produced or shipped are quantified, and the quality is guaranteed.

[0045] The melting point of the polyamide resin is preferably 150°C or higher, more preferably 180°C or higher, and even more preferably 200°C or higher, and is preferably 350°C or lower, more preferably 330°C or lower, and even more preferably 300°C.

[0046] The polyamide resin preferably has a lower limit of number average molecular weight (Mn) of 6,000 or more, more preferably 8,000 or more, and even more preferably 10,000 or more, and is preferably 100,000 or less, more preferably 50,000 or less. Within such ranges, the heat resistance, elastic modulus, dimensional stability, and moldability are improved.

[0047] In addition to the resin, the resin film may contain additives such as elastomers, antioxidants, stabilizers such as heat stabilizers, hydrolysis resistance improvers, weathering stabilizers, matting agents, UV absorbers, nucleating agents, plasticizers, dispersants, flame retardants, antistatic agents, coloring inhibitors, antigelling agents, colorants, and release agents, as long as they do not deviate from the spirit of the present invention. For details, see paragraphs 0130-0155 of Japanese Patent No. 4,894,982 and paragraphs 0047-0103 of International Publication No. 2021 / 241471, the contents of which are incorporated herein by reference. The total amount of these additives is preferably 0% by mass or more and less than 10% by mass of the resin film, more preferably 0% by mass or more and less than 5% by mass, even more preferably 0% by mass or more and less than 3% by mass, and even more preferably 0% by mass or more and less than 1% by mass.

[0048] Next, the size of the substrate will be described. The thickness of the substrate used in this embodiment is not particularly limited as long as stitching is possible, but is preferably 200 μm or less, more preferably 175 μm or less, even more preferably 150 μm or less, and preferably 20 μm or more, more preferably 30 μm or more, and even more preferably 40 μm or more. By making it below the upper limit value, it becomes easier for the needle to penetrate during stitching, and it becomes easier to stitch multiple layers of reinforcing fibers together. Furthermore, by making it above the lower limit value, it is possible to make the substrate less likely to break during processing.

[0049] The size of the substrate in this embodiment is not specified, but the surface area of ​​one side of the film is 4 m ２ Preferably, it is 3 m or less. ２ More preferably, it is 2 m or less. ２ It is more preferable that the thickness is 0.01 m or less. ２ It is preferable that the thickness is 0.02 m or more. ２ More preferably, it is 0.03 m or more. ２It is more preferable that the thickness is equal to or greater than the upper limit. By setting the thickness equal to or less than the upper limit, it is possible to continuously produce multiple preforms during TFP processing without replacing the substrate after producing one preform, which tends to improve processing efficiency. Furthermore, by setting the thickness equal to or greater than the lower limit, the length of the preform cut to the size to be set in the molding die after production becomes shorter, which tends to shorten the processing time.

[0050] The shape of the substrate in this embodiment is not particularly limited, but is preferably a regular polygon or a circle. In this embodiment, the mixed yarns are arranged radially and regularly, so these shapes can reduce the amount of material used. In this embodiment, the center of the substrate is preferably the center of gravity of the regular polygon or the center of the circle.

[0051] The mixed yarn used in this embodiment contains reinforcing fiber bundles and thermoplastic resin fibers, and typically 90% by mass or more (preferably 95% by mass or more, more preferably 99% by mass or more) of the mixed yarn is made up of reinforcing fiber bundles and thermoplastic resin fibers.

[0052] Next, the reinforcing fiber bundles contained in the mixed yarn used in this embodiment will be described. The reinforcing fiber bundles used in this embodiment are preferably continuous reinforcing fiber bundles. Continuous reinforcing fiber bundles refer to fibers with a number average fiber length of more than 6 mm, preferably 5 cm or more, more preferably 10 cm or more, and even more preferably 1 m or more. There is no particular upper limit for the continuous reinforcing fiber bundle, but if one ply of prepreg contains one mixed yarn, the upper limit will be the length corresponding to the length of that mixed yarn. The cross section of the reinforcing fiber bundle may be circular or flat.

[0053] Examples of the reinforcing fibers constituting the reinforcing fiber bundle used in this embodiment include inorganic fibers such as glass fibers, carbon fibers, alumina fibers, boron fibers, ceramic fibers, and metal fibers (steel fibers, etc.), and organic fibers such as plant fibers (including kenaf and bamboo fibers), aramid fibers, polyoxymethylene fibers, aromatic polyamide fibers, polyparaphenylene benzobisoxazole fibers, and ultra-high molecular weight polyethylene fibers. Among these, it is preferable to include at least one of carbon fibers, aramid fibers, and glass fibers, more preferably to include at least one selected from carbon fibers and glass fibers, and even more preferably to include carbon fibers.

[0054] The reinforcing fiber bundles used in a preferred embodiment of this embodiment are preferably treated with a treatment agent. Examples of such treatment agents include sizing agents and surface treatment agents, and those described in paragraphs 0093 and 0094 of Japanese Patent No. 4,894,982 are preferably used, the contents of which are incorporated herein by reference.

[0055] Examples of surface treatment agents include functional compounds such as epoxy compounds, acrylic compounds, isocyanate compounds, silane compounds, and titanate compounds, and examples of such agents include silane coupling agents and titanate coupling agents, with silane coupling agents being preferred.

[0056] The sizing agent is preferably at least one of an epoxy resin, a urethane resin, a silane compound, an isocyanate compound, a titanate compound, and a polyamide resin, more preferably at least one of an epoxy resin, a urethane resin, a silane coupling agent, a water-insoluble polyamide resin, and a water-soluble polyamide resin, even more preferably at least one of an epoxy resin, a urethane resin, a water-insoluble polyamide resin, and a water-soluble polyamide resin, and even more preferably a water-soluble polyamide resin.

[0057] The amount of the treatment agent is preferably 0.001 to 1.5% by mass, more preferably 0.1 to 1.2% by mass, and even more preferably 0.3 to 1.1% by mass of the reinforcing fiber bundle.

[0058] A known method can be used to treat the reinforcing fiber bundle with a treatment agent. For example, the reinforcing fiber bundle can be immersed in a solution in which the treatment agent is dissolved, and the treatment agent is adhered to the surface of the reinforcing fiber bundle. The treatment agent can also be air-blowed onto the surface of the reinforcing fiber bundle. Furthermore, a reinforcing fiber bundle that has already been treated with a surface treatment agent or a treatment agent may be used, or a commercially available surface treatment agent or a treatment agent may be washed off and then the surface may be treated again to obtain the desired amount of treatment agent.

[0059] The density of the reinforcing fiber bundle used in this embodiment (the density of the reinforcing fiber bundle in formula (A)) is 1.5 g / cm ３ It is preferable that the density is 1.7 g / cm or more. ３ More preferably, it is 1.75 g / cm or more. ３ More preferably, it is 3.0 g / cm or more. ３ It is preferable that the density is 2.8 g / cm or less. ３ More preferably, it is 2.7 g / cm or less. ３ More preferably, it is 2.0 g / cm or less. ３ It is more preferable that the density is equal to or less than the upper limit. By setting the density equal to or less than the upper limit, the weight of the molded product tends to be reduced. When two or more types of reinforcing fibers are contained, the density is the sum (weighted average value) of the values ​​obtained by multiplying the density of each reinforcing fiber by the mass fraction of each reinforcing fiber.

[0060] The thickness of the reinforcing fiber bundle used in this embodiment (thickness of the reinforcing fiber bundle in formula (A)) is preferably 500 tex or more, more preferably 700 tex or more, and preferably 2500 tex or less, more preferably 2000 tex or less, even more preferably 1500 tex or less, and even more preferably 1000 tex or less. By setting it to the lower limit value or more, when producing a preform of the same trajectory, the number of fibers is large, so that the TFP processing time tends to be shorter than when there are fewer fibers. Furthermore, by setting it to the upper limit value or less, there is a tendency that a preform having finer portions can be produced. When two or more types of reinforcing fibers are contained, the sum (weighted average value) of the values ​​obtained by multiplying the thickness of each reinforcing fiber by the mass fraction of each reinforcing fiber is used.

[0061] In this embodiment, the proportion of reinforcing fiber bundles in the mixed yarn is preferably 35% by volume or more, more preferably 40% by volume or more, even more preferably 45% by volume or more, and even more preferably 48% by volume or more. By making it equal to or greater than the above-mentioned lower limit, the mechanical strength of the obtained molded product tends to be further improved. The proportion of the reinforcing fiber bundles in the mixed yarn is preferably 65% ​​by volume or less, more preferably 60% by volume or less, even more preferably 55% by volume or less, even more preferably 58% by volume or less, and even more preferably 53% by volume or less. By making it equal to or less than the above-mentioned upper limit, the press moldability of the obtained prepreg tends to be better. Only one type of reinforcing fiber bundle may be used, or two or more types may be used. When two or more types are used, it is preferable that the total amount is within the above-mentioned range.

[0062] Next, the thermoplastic resin fiber contained in the mixed yarn will be described. The thermoplastic resin fiber used in this embodiment is preferably composed of a thermoplastic resin composition containing a thermoplastic resin (the thermoplastic resin composition may consist only of a thermoplastic resin). The thermoplastic resin fiber used in this embodiment is preferably a thermoplastic resin fiber bundle. The thermoplastic resin fiber is preferably a continuous thermoplastic resin fiber. Continuous thermoplastic resin fiber refers to a fiber having a number average fiber length of more than 6 mm, preferably 5 cm or more, more preferably 10 cm or more, and even more preferably 1 m or more. There is no particular upper limit for the continuous thermoplastic resin fiber, but if one ply of prepreg contains one mixed yarn, the upper limit will be the length corresponding to the length of that mixed yarn. The cross section of the continuous thermoplastic resin fiber may be circular or flat.

[0063] The thickness of the thermoplastic resin fiber (preferably a thermoplastic resin fiber bundle) used in this embodiment is preferably 40 to 600 dtex, more preferably 50 to 500 dtex, and even more preferably 100 to 400 dtex. The thermoplastic resin fiber used in this embodiment can be formed from a thermoplastic resin composition. The thermoplastic resin composition may consist of only one or more thermoplastic resins, or may contain other components.

[0064] The thermoplastic resin is preferably a crystalline thermoplastic resin. Examples of the thermoplastic resin include polyolefin resins such as polyethylene and polypropylene, polyester resins such as polyamide resins, polyethylene terephthalate and polybutylene terephthalate, polycarbonate resins, polyoxymethylene resins, polyetherketone, polyetheretherketone, polyetherketoneketone, polyetheretherketoneketone, and other polyetherketone resins, polyethersulfone resins, polyethersulfide resins, thermoplastic polyetherimides, thermoplastic polyamideimides, wholly aromatic polyimides, and thermoplastic polyimide resins such as semi-aromatic polyimides. The polyamide resin used in this embodiment is not particularly limited in type, and may be either an aliphatic polyamide resin or a semi-aromatic polyamide resin, but is more preferably a semi-aromatic polyamide resin. The preferred range of the polyamide resin is the same as that of the polyamide resin described in the section on the resin film as the substrate.

[0065] In addition to the thermoplastic resin, the thermoplastic resin fiber may contain additives such as elastomers, antioxidants, stabilizers such as heat stabilizers, hydrolysis resistance improvers, weathering stabilizers, delustering agents, UV absorbers, nucleating agents, plasticizers, dispersants, flame retardants, antistatic agents, coloring inhibitors, antigelling agents, colorants, and release agents, as long as they do not deviate from the spirit of the present invention. For details, see paragraphs 0130-0155 of Japanese Patent No. 4,894,982 and paragraphs 0047-0103 of International Publication No. WO 2021 / 241471, the contents of which are incorporated herein by reference. The total amount of these additives is preferably 0% to less than 10% by weight of the resin film, more preferably 0% to less than 5% by weight, even more preferably 0% to less than 3% by weight, and even more preferably 0% to less than 1% by weight.

[0066] In this embodiment, an example is given in which 80% by mass or more (preferably 90% by mass or more, more preferably 95% by mass or more, and even more preferably 98% by mass or more) of the thermoplastic resin fibers is a thermoplastic resin (preferably a polyamide resin).

[0067] The thermoplastic resin fiber in this embodiment is preferably a continuous thermoplastic resin fiber having a treatment agent on its surface. For details, please refer to paragraphs 0064 to 0065 of WO 2016 / 159340, the contents of which are incorporated herein by reference. By including a surface treatment agent in the thermoplastic resin fiber, breakage of the thermoplastic resin fiber during processing can be more effectively suppressed. The amount of the surface treatment agent in the thermoplastic resin fiber is, for example, 0.1 to 2.0 mass% of the thermoplastic resin fiber. The lower limit is preferably 0.5 mass% or more, more preferably 0.8 mass% or more. The upper limit is preferably 1.8 mass% or less, more preferably 1.5 mass% or less. By setting the amount within this range, the dispersion of the thermoplastic resin fiber is improved. The type of surface treatment agent is not particularly limited, as long as it has the function of converging the thermoplastic resin fiber. As the treatment agent, ester-based compounds, alkylene glycol-based compounds, polyolefin-based compounds, phenyl ether-based compounds, polyether-based compounds, silicone-based compounds, polyethylene glycol-based compounds, amide-based compounds, sulfonate-based compounds, phosphate-based compounds, carboxylate-based compounds, and combinations of two or more of these are preferred, and ester-based compounds are more preferred.

[0068] The thermoplastic resin fiber preferably has a moisture regain of 5% or less, more preferably 4.5% or less, even more preferably 4% or less, even more preferably 3% or less, and even more preferably 2% or less, as measured in accordance with JIS L 1096. The lower limit may be 0%, but a value of 0.001% or more is practical. The moisture regain is measured in accordance with JIS L 1096.

[0069] The method of treating thermoplastic resin fibers with a surface treatment agent is not particularly limited as long as the intended purpose can be achieved. For example, a solution of the surface treatment agent may be added to the thermoplastic resin fibers to adhere the treatment agent to the surface of the thermoplastic resin fibers. Alternatively, the treatment agent may be applied to the surface of the thermoplastic resin fibers by air blowing.

[0070] In this embodiment, the proportion of thermoplastic resin fibers in the mixed yarn is preferably 15% by mass or more, more preferably 20% by mass or more, even more preferably 25% by mass or more, and even more preferably 30% by mass or more. By setting the proportion at or above the lower limit, the abrasion resistance tends to be better. The proportion of thermoplastic resin fibers in the mixed yarn is preferably 80% by mass or less, more preferably 75% by mass or less, even more preferably 70% by mass or less, even more preferably 65% ​​by mass or less, and even more preferably 60% by mass or less. By setting the proportion at or below the upper limit, the mechanical strength of the obtained molded product tends to be further improved. Only one type of thermoplastic resin fiber may be used, or two or more types may be used. When two or more types are used, the total amount is preferably within the above range. In the mixed yarn of this embodiment, the total of the reinforcing fibers and the thermoplastic resin fibers preferably accounts for 90% by mass or more of the mixed yarn, more preferably 95% by mass or more, even more preferably 97% by mass or more, and even more preferably 99% by mass or more.

[0071] The impregnation rate of the mixed yarn used in this embodiment is preferably 10% or less, more preferably 5% or less, and even more preferably 3% or less. The lower limit of the impregnation rate of the mixed yarn is 0% or more. The lower the impregnation rate of the mixed yarn, the higher the proportion of the thermoplastic resin fiber that does not melt and remains in a fibrous state. In contrast, the impregnation rate of a UD tape is usually 100%. The impregnation rate of the mixed yarn is measured by the following method.

[0072] <Method for measuring the impregnation rate of a mixed yarn> The mixed yarn is embedded in epoxy resin, the surface corresponding to the cross section of the mixed yarn is polished, and the cross section is photographed using an ultra-deep color 3D shape measuring microscope. The cross section of the region corresponding to the mixed yarn of the epoxy resin-embedded sample is observed using a digital microscope. From the obtained cross section photograph, the region where the thermoplastic resin has impregnated between the continuous carbon fibers in the mixed yarn is selected using image analysis software ImageJ, and its area is measured. The impregnation rate is expressed as the region where the resin has impregnated into the continuous reinforcing fibers / cross-sectional area (unit: %). The ultra-deep color 3D shape measuring microscope used is a VK-9500 (controller unit) / VK-9510 (measurement unit) (manufactured by Keyence Corporation).

[0073] The dispersity of the mixed yarn used in this embodiment is preferably 50% or more, more preferably 80% or more, and even more preferably 90% or more. The upper limit of the dispersity of the mixed yarn is 100%. The higher the dispersity of the mixed yarn, the more evenly the thermoplastic resin fibers are distributed within a single mixed yarn, without any regions biased toward thermoplastic resin fibers or regions biased toward thermoplastic resin fibers. The dispersity of the mixed yarn is measured by the following method.

[0074] <Method for measuring the degree of dispersion of a mixed yarn> The mixed yarn is embedded in epoxy resin, and a cross section perpendicular to the longitudinal direction of the mixed yarn is polished. The cross section of the part corresponding to the mixed yarn is photographed using an ultra-deep color 3D shape measuring microscope. As shown in Figure 16, six auxiliary lines are drawn radially at equal intervals on the photographed image, and the length of the reinforcing fiber region in the mixed yarn on each auxiliary line is measured as a1, a2, a3... ai (i = n). In addition, the length of the thermoplastic resin fiber region on each auxiliary line is measured as b1, b2, b3... bi (i = m). Based on the results, the degree of dispersion is calculated using the following formula. The ultra-deep color 3D shape measuring microscope used is VK-9500 (controller unit) / VK-9510 (measuring unit) (manufactured by Keyence).

[0075] Next, the shape-retaining yarn will be described. The shape-retaining yarn used in this embodiment is not particularly limited in type, provided that it is capable of retaining the shape of the mixed yarn in the base material. However, it is preferably a thermoplastic resin yarn, and more preferably a crystalline thermoplastic resin fiber yarn. Examples of the thermoplastic resin contained in the thermoplastic resin yarn include polyolefin resins such as polyethylene and polypropylene, polyester resins such as polyamide resin, polyethylene terephthalate and polybutylene terephthalate, polycarbonate resin, polyoxymethylene resin, polyetherketone, polyetheretherketone, polyetherketoneketone, polyetheretherketoneketone, and other polyetherketone resins, polyethersulfone resin, polyethersulfide resin, thermoplastic polyetherimide, thermoplastic polyamideimide, fully aromatic polyimide, semi-aromatic polyimide, and other thermoplastic polyimide resins. A polyamide resin is preferred. The type of polyamide resin used in this embodiment is not particularly limited, and it may be an aliphatic polyamide resin or a semi-aromatic polyamide resin, but a semi-aromatic polyamide resin is more preferred. The preferred range of polyamide resin is the same as that of the polyamide resin described in the section on resin film as a substrate. In addition to the thermoplastic resin, the thermoplastic resin yarn may contain additives such as elastomers, antioxidants, stabilizers such as heat stabilizers, hydrolysis resistance improvers, weathering stabilizers, matting agents, UV absorbers, nucleating agents, plasticizers, dispersants, flame retardants, antistatic agents, coloring inhibitors, antigelling agents, colorants, and release agents, within the scope of the present invention. For details, please refer to the descriptions in paragraphs 0130 to 0155 of Japanese Patent No. 4,894,982 and the descriptions in paragraphs 0047 to 0103 of International Publication No. 2021 / 241471, the contents of which are incorporated herein by reference. The total amount of these components is preferably 0% by mass or more and less than 10% by mass of the thermoplastic resin yarn, more preferably 0% by mass or more and less than 5% by mass, even more preferably 0% by mass or more and less than 3% by mass, and even more preferably 0% by mass or more and less than 1% by mass.

[0076] In this embodiment, 80% by mass or more (preferably 90% by mass or more, more preferably 95% by mass or more, and even more preferably 98% by mass or more) of the thermoplastic resin yarn is a thermoplastic resin (preferably a polyamide resin). The thickness of the shape-retaining yarn can be, for example, 10 to 200 dtex, preferably 50 to 150 dtex, and more preferably 100 to 150 dtex.

[0077] In the prepreg of this embodiment, the substrate is a resin film, the shape-retaining yarn is a thermoplastic resin yarn, and the difference in melting point between the substrate, the thermoplastic resin fiber, and the thermoplastic resin yarn is preferably within 10°C. This configuration allows for uniform molding by heat processing. The difference in melting point is preferably within 8°C, more preferably within 5°C. Furthermore, it is preferable that 80% by mass or more of the composition constituting the resin film, the thermoplastic resin fiber, and the thermoplastic resin yarn is common, more preferably 90% by mass or more, even more preferably 95% by mass or more, and even more preferably 99% by mass or more. This configuration allows for a molded product with a better appearance to be obtained.

[0078] FIG. 7 is a schematic diagram showing a second example of a prepreg of this embodiment. The second example is preferably similar to the first example unless otherwise specified. In the prepreg in FIG. 7 , the mixed yarn 2 (and further the reinforcing fibers in the mixed yarn) is arranged at an angle of approximately 60° with respect to a line passing through the center of the substrate. In this embodiment, a prepreg of this shape can also be manufactured using a single mixed yarn. The prepreg shown in FIG. 7 can also be made into a disk-shaped prepreg by cutting the interior and edges. The prepreg shown in FIG. 7 also preferably has circular stitchings 4, 5, and 6 formed with a shape-retaining yarn, centered on the center 3 of the substrate 1. In particular, by providing circular stitchings 5 ​​and 6, the interior and edges of the prepreg can also be easily cut.

[0079] In the case of the prepreg shown in Fig. 7, the fibers are arranged at an angle α of more than 10° and less than 90° with respect to a line passing through the center of the substrate. Here, the angle α in the prepreg of Fig. 7 is preferably 20° or more, and may be 25° or more, 30° or more, or 40° or more, and is preferably 80° or less, and may be 75° or less, 70° or less, 60° or less, or 50° or less.

[0080] Figures 8 to 13 show photographs of the prepreg produced according to the schematic diagram of Figure 7. Starting from Figure 8, they are a plan view, a bottom view, a front view, a back view, a left side view, and a right side view, in that order.

[0081] Figure 14 is a partially enlarged photograph of the prepreg of Figure 8. 12 indicates the widest distance between reinforcing fiber bundles.

[0082] Next, the multilayer body of this embodiment will be described. The multilayer body of this embodiment is a multilayer body having two or more plies of the prepreg of this embodiment, and the centers of the two or more plies of prepreg are on the same axis. Figure 15 is a schematic diagram showing an example of the multilayer body of this embodiment, where (a) is a view of the stacked prepregs as seen from the thickness direction of the prepregs, and (b) is a view as seen from above when (a) is a side view. In Figure 15, reference numeral 13 indicates an axis, and 14 indicates a prepreg. In Figure 15(a), multiple plies of prepreg 14 are passed through the axis 13, and these prepregs are stacked so that they are on the same axis. Here, the axis 13 corresponds to the position of the center 3 of the base material of the prepreg 14.

[0083] In the embodiment of Fig. 15, as shown in Fig. 15(b), the diameter of the shaft 13 is preferably sized to fit into the hole cut by the circular stitching 4. This configuration allows the shafts to be neatly aligned, allowing the prepregs 14 to be stacked more precisely. Furthermore, when threading the prepregs 14 onto the shaft 13, the perforations in the circular stitching 4 make it easy to cut the interior of the circular stitching 4 (substrate 1).

[0084] 15 is cut at the circular stitching 5 and the circular stitching 6. That is, it is preferable that the positions of the circular stitching 5 and the circular stitching 6 of all prepregs constituting the multilayer body are the same in the direction perpendicular to the lamination direction of the multilayer body (the direction as viewed from FIG. 15(b)). Cutting may be performed before or after the heat and pressure processing.

[0085] In the multilayer body of this embodiment, it is preferable that one or more plies of prepreg 14 are arranged at an angle greater than 0° and less than 10° relative to a line passing through the center of the substrate, and one or more other plies of prepreg 14 are arranged at an angle greater than 10° and less than 90° relative to a line passing through the center of the substrate. For example, a multilayer body in which both the first example prepreg and the second example prepreg are laminated can be exemplified. This configuration allows the reinforcing fibers to spread in multiple directions, resulting in a molded product with higher strength in multiple directions. It is also possible to laminate a prepreg in which the mixed fiber yarn is arranged at a 90° angle relative to a line passing through the center of the substrate. In the multilayer body of this embodiment, it is preferable to laminate four or more plies of prepreg, more preferably five or more plies, even more preferably eight or more plies, even more preferably ten or more plies, and preferably 20 or less plies.

[0086] It is preferable that the prepreg lamination structure is symmetrical in the lamination direction with respect to the center of the lamination direction. For example, as shown in Figure 15(a), it is preferable that the layer structure of the prepreg multilayer body is prepreg A / prepreg B / prepreg C / prepreg D / prepreg E / prepreg F / prepreg F / prepreg E / prepreg D / prepreg C / prepreg B / prepreg A. In this case, the prepregs A are prepregs (usually the same prepreg) in which the mixed yarns are arranged at the same angle with respect to a line passing through the center of the base material. The same applies to prepregs B to F. Also, for example, prepregs B and C may be the same prepreg. It is preferable that the prepregs constituting the multilayer body are composed of at least four or more types (preferably eight or less types, more preferably six or less types) of prepregs having different angles α at which the mixed yarns are arranged. All of the prepregs constituting the multilayer body of this embodiment may be the prepregs of this embodiment, or a portion of the prepregs may contain other prepregs.

[0087] The prepreg and multilayer body of this embodiment are preferably heat-processed and used as a molded article. The molded article is preferably cylindrical or ring-shaped, and specific examples include flanges. The thickness of the molded article of the prepreg of this embodiment, in the case of a molded article of one prepreg ply, is preferably 0.05 mm or more, more preferably 0.07 mm or more, even more preferably 0.1 mm or more, still more preferably 0.13 mm or more, and even more preferably 0.15 mm or more, and is preferably 10 mm or less, more preferably 5 mm or less, still more preferably 3 mm or less, still more preferably 1 mm or less, and even more preferably 0.5 mm or less.

[0088] The thickness of the flange of the molded article obtained by heat processing the multilayer molded article of this embodiment is preferably 0.1 mm or more, more preferably 0.5 mm or more, and preferably 5 mm or less, more preferably 4 mm or less. The outer diameter of the cylindrical or ring-shaped molded article of this embodiment is preferably 150 mm or more, more preferably 200 mm or more, and preferably 300 mm or less, more preferably 280 mm or less. The inner diameter of the cylindrical or ring-shaped molded article of this embodiment is preferably 50 mm or more, more preferably 70 mm or more, and preferably 140 mm or less, more preferably 120 mm or less. The heating temperature of the prepreg and the multilayered article is preferably 10 to 60°C above the melting point of the thermoplastic resin fiber contained in the prepreg. Furthermore, when pressure is applied, pressure is preferably applied at 1 to 10 MPa. The heating time and pressure application time are each 1 minute to 1 hour, and heating and pressure application may be performed simultaneously or separately.

[0089] The present invention will be explained in more detail below with reference to examples. The materials, amounts used, ratios, treatment contents, treatment procedures, etc. shown in the following examples can be changed as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention is not limited to the specific examples shown below. If the measuring instruments used in the examples are difficult to obtain due to discontinuation or the like, measurements can be made using other instruments with equivalent performance.

[0090] <Thermoplastic Resin> <<Synthesis Example 1: MPXD10>> A reaction vessel equipped with a stirrer, a partial condenser, a total condenser, a thermometer, a dropping funnel, a nitrogen inlet tube, and a strand die was charged with 10 kg (49.4 mol) of sebacic acid (TA grade, manufactured by Ito Oil Mills, Ltd.) and 11.66 g of sodium acetate / sodium hypophosphite monohydrate (molar ratio=1 / 1.5). The atmosphere was thoroughly replaced with nitrogen, and then the system was heated to 170°C and melted under a small amount of nitrogen flow while being stirred. 6.647 kg of a mixed xylylenediamine (34.16 mol of metaxylylenediamine, 14.64 mol of paraxylylenediamine, manufactured by Mitsubishi Gas Chemical Co., Inc.) with a molar ratio of 70 / 30 (34.16 mol of metaxylylenediamine, 14.64 mol of paraxylylenediamine) was added dropwise to molten sebacic acid under stirring, and the resulting condensed water was discharged from the system while the internal temperature was continuously raised to 240 ° C over 2.5 hours. After the dropwise addition was completed, the internal temperature was increased, and when it reached 250 ° C, the pressure inside the reaction vessel was reduced, and the internal temperature was further increased to 255 ° C for 20 minutes, and the melt polycondensation reaction was continued. Thereafter, the system was pressurized with nitrogen, and the resulting polymer was removed from the strand die and pelletized to obtain polyamide resin MPXD10. The melting point of the resulting polyamide resin was 213 ° C and the number average molecular weight was 15,400.

[0091] <Continuous reinforcing fiber> <<Continuous carbon fiber (CF)>> Mitsubishi Rayon Co., Ltd., Pyrofil-TR-50S-12000-AD, 800 tex, 12,000 fiber count, density 1.76 g / cm ３ The surface is treated with epoxy resin.

[0092] <Production of Continuous Thermoplastic Resin Fiber> The MPXD10 obtained in Synthesis Example 1 above was melt-extruded using a single-screw extruder having a screw diameter of 30 mm, extruded into a strand shape from a die with 60 holes, and stretched while being wound on a roll, and a continuous thermoplastic resin fiber bundle of 800 m was wound onto a winder. The melting temperature was the melting point of MPXD10 + 15°C.

[0093] <Production of Thermoplastic Resin Film> The MPXD10 obtained in Synthesis Example 1 above was melt-extruded using a single-screw extruder with a 30 mm diameter screw, extruded from a 1.5 m wide die, stretched while being wound on a roll, and wound into a 50 m long roll. After winding, both edges were cut to obtain a 1.0 m wide film. The melting temperature was set to the melting point of MPXD10 + 15°C.

[0094] <Production of mixed yarn> The mixed yarn was produced according to the following method. Fibers were pulled out from a continuous thermoplastic resin fiber winding and a continuous carbon fiber winding, and then spread by air blowing while passing through multiple guides. While spreading, the continuous thermoplastic resin fiber and continuous carbon fiber were bundled together, and further, air blowing was applied while passing through multiple guides to promote homogenization, thereby obtaining a mixed yarn. The obtained mixed yarn had a pick-up rate of 3% or less and a degree of dispersion of 90% or more.

[0095] Example 1: The mixed yarn obtained above was stitched onto the surface of the thermoplastic resin film obtained above using a shape-retaining yarn by tailored fiber placement processing, as shown in the schematic diagram in Figure 1, to obtain a prepreg. The shape-retaining yarn was the continuous thermoplastic resin fiber bundle obtained above. Figure 3 shows a photograph of the obtained prepreg. The widest distance between reinforcing fibers in the prepreg was measured and found to be 3.7 mm. Circular stitching 4 could be easily cut by piercing it with a metal rod. Circular stitchings 5 ​​and 6 could also be easily cut. The obtained prepreg was sandwiched between metal plates and press-molded at a temperature of the melting point of MPXD10 + 40°C and a pressure of 2 MPa for 15 minutes, resulting in a molded product with a thickness of 0.23 mm. The volume of the reinforcing fibers in the molded product relative to the volume of the molded product was 48.7% by volume.

[0096] Example 2 The same procedure as in Example 1 was carried out except that TFP processing was performed in accordance with the schematic diagram shown in Figure 7 instead of the schematic diagram shown in Figure 1. Photographs of the resulting prepreg are shown in Figures 8 to 13. Furthermore, as shown in Figure 14, the widest distance between reinforcing fibers in the prepreg was measured. The widest distance between reinforcing fibers was 2.9 mm. The resulting prepreg was sandwiched between metal plates and press-molded at a temperature of the melting point of MPXD10 + 40 ° C and a pressure of 2 MPa for 15 minutes to obtain a molded product with a thickness of 0.32 mm. The volume of reinforcing fibers in the molded product relative to the volume of the molded product was 48.7 vol%.

[0097] Example 3: In Example 1, prepregs were produced with the widest inter-fiber distance varied from 0.3 mm to 4.0 mm in 0.1 mm increments, and the thickness of the resulting molded article was measured. When the widest inter-fiber distance was between 2.3 mm and 4.0 mm, the thickness was between 0.406 mm and 0.223 mm, resulting in prepregs capable of providing molded articles with a good balance between strength and thickness unevenness. Detailed results are shown in Figure 17. The horizontal axis, Roving distance, indicates the maximum inter-fiber distance, and Layer thickness indicates the thickness of the molded article.

[0098] Although the present invention has been described in detail with reference to specific embodiments, it will be apparent to those skilled in the art that various modifications can be made without departing from the spirit and scope of the invention.

[0099] REFERENCE SIGNS LIST 1 Base film 2 Blended fiber yarn 3 Center 4 Circular stitching 5 Circular stitching 6 Circular stitching 9 Widest distance between reinforcing fiber bundles 10 Shape-retaining yarn 11 Shape-retaining start point 12 Widest distance between reinforcing fiber bundles 13 Axis 14 Prepreg

Claims

1. A prepreg comprising a substrate, a mixed fiber yarn provided on the substrate, and a shape-retaining yarn that retains the shape of the mixed fiber yarn on the substrate, wherein the mixed fiber yarn comprises a thermoplastic resin fiber and a reinforcing fiber bundle, and is regularly arranged radially around an arbitrary point on the substrate, and wherein the distance between adjacent reinforcing fiber bundles in the prepreg, which is the widest distance between reinforcing fiber bundles, satisfies the following formula (A): Formula (A) Distance between reinforcing fiber bundles (mm) = [thickness of reinforcing fiber bundle (tex)] / [10 × density of reinforcing fiber bundle (g / cm ３ ) × thickness of molded article (mm) × volume of reinforcing fibers in the molded article relative to the volume of the molded article (volume %)] (In formula (A), the molded article is a molded article obtained by press-molding the prepreg at a temperature of the melting point of the thermoplastic resin contained in the thermoplastic resin fiber + 40°C and a pressure of 2 MPa for 15 minutes. The thickness of the molded article is 0.05 to 1 mm.) 2. The prepreg according to claim 1, wherein the reinforcing fibers contained in the mixed yarn are arranged at an angle of more than 0° and not more than 10° relative to a line passing through the center of the substrate.

3. The prepreg according to claim 1, wherein the reinforcing fibers contained in the mixed yarn are arranged at an angle of more than 10° and less than 90° with respect to a line passing through the center of the substrate.

4. A prepreg according to any one of claims 1 to 3, wherein the substrate is a resin film, the shape-retaining yarn is a thermoplastic resin yarn, and the difference in melting point between the substrate, the thermoplastic resin fiber, and the thermoplastic resin yarn is within 10°C.

5. A prepreg comprising a substrate, a mixed yarn continuously provided on the substrate, and a shape-retaining yarn that retains the shape of the mixed yarn on the substrate, wherein the mixed yarn comprises a thermoplastic resin fiber and a reinforcing fiber bundle and is regularly arranged radially around an arbitrary point on the substrate as a center.

6. A prepreg according to any one of claims 1 to 5, wherein the mixed yarn is a single yarn.

7. The prepreg according to any one of claims 1 to 6, which is a fiber placement prepreg.

8. A prepreg according to any one of claims 1 to 7, wherein circular stitching centered on the center of the substrate is provided by a shape-retaining thread.

9. A multilayer body having two or more plies of the prepreg according to any one of claims 1 to 8, wherein the centers of the two or more plies of prepreg are on the same axis.

10. The multilayer body according to claim 9, wherein one or more plies of the prepreg are oriented at an angle greater than 0° and less than 10° relative to a line passing through the center of the substrate, and one or more other plies of the prepreg are oriented at an angle greater than 10° and less than 90° relative to a line passing through the center of the substrate.

11. A molded product obtained by heat processing the multilayer body according to claim 9 or 10.

12. A flange obtained by heat processing the multilayer body according to claim 9 or 10.

13. A method for producing a prepreg, comprising: subjecting a mixed fiber yarn to tailored fiber placement processing on a substrate using a shape-retaining yarn so that the mixed fiber yarn is regularly arranged radially from an arbitrary point on the substrate as a center; wherein the mixed fiber yarn contains the thermoplastic resin fiber and reinforcing fiber.

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