Laminated preform

Abstract

The present invention addresses the problem of providing a laminated preform having excellent shaping properties and handleability suitable for press molding and stamping molding. Provided is a laminated preform in which a plurality of sheet-shaped composite materials including continuous reinforcing fibers and a thermoplastic resin as a matrix resin are laminated. In the plurality of sheet-shaped composite materials, adjacent sheet-shaped composite materials in the thickness direction have joint portions and non-joint portions and are joined at the joint portions, and in each sheet-shaped composite material, the ratio of the total area of the joint portions on the front and back surfaces to the total area of the non-joint portions on the front and back surfaces (total area of the joint portions / total area of the non-joint portions) is 5 / 95 to 40 / 60 when the sum of the total area of the joint portions and the total area of the non-joint portions is 100.

Description

Laminated Preform

[0001] The present invention relates to a laminate preform.

[0002] Fiber-reinforced composite materials are materials that combine reinforcing fibers with a matrix resin, and because they are lightweight and have excellent strength and rigidity, they are used in a wide range of applications, including aerospace, transportation and mobility, and civil engineering and construction. Currently, most fiber-reinforced composite materials combine reinforcing fibers with thermosetting resins, but the development of composite materials that use thermoplastic resins as the matrix resin is accelerating from the perspectives of recyclability, short molding cycles, post-processing such as welding, and improved impact resistance of molded products.

[0003] In particular, continuous fiber-reinforced composite materials using thermoplastic resins are often molded by laminating multiple sheets of composite material to form a preform with a predetermined fiber orientation, and then using press molding or stamping to obtain a molded product. The quality of the laminated preform is important in ensuring the ease of handling and transport of the preform during molding.

[0004] For example, when performing stamping molding, if a laminate preform is preheated to a predetermined temperature using an infrared heater and then transported to a press molding die using an automatic process, it would be inconvenient if the laminate of the laminate preform collapsed and fell off during transport, preventing good molding. Furthermore, it is preferable to allow any gas remaining in the laminate preform to easily escape so that no air bubbles (voids) remain inside during press molding. Furthermore, when shaping a laminate preform by press molding, it is preferable that it can smoothly follow bending deformation and drawing deformation according to the desired shape.

[0005] Patent Document 1 discloses a thermoplastic resin multilayer reinforced sheet material in which multiple thermoplastic resin reinforced sheet materials are laminated together, and also mentions a state in which the thermoplastic resin sheet materials are partially heat-sealed and laminated. It is stated that by doing so, a high-quality thermoplastic resin multilayer reinforced sheet material with excellent mechanical properties and drapeability can be obtained. However, there is no disclosure regarding the ratio of heat-sealed joints to non-bonded joints or the bonding strength of the heat-sealed joints. Therefore, proposals for laminated preforms with excellent handleability are anticipated.

[0006] Patent Document 2 discloses a multilayer reinforcing sheet material in which a plurality of thermoplastic resin reinforcing sheet materials, each of which is provided with an adhesive thermoplastic resin having a melting point lower than that of the matrix resin, are laminated on a reinforcing fiber sheet substrate made of reinforcing fibers and a thermoplastic matrix resin, and partially bonded together, and describes that the shapeability and drapeability are improved while maintaining the cohesion of the multilayer sheet. However, this document also does not disclose the ratio of heat-sealed joints to non-jointed parts or the bonding strength of the heat-sealed joints, and a proposal for a laminate preform with excellent handleability is expected.

[0007] JP 2006-76158 A JP 2008-149708 A

[0008] In view of the above background, an object of the present invention is to provide a laminate preform that is excellent in handleability and formability.

[0009] The present invention employs the following means to solve the above problems. [1] A laminated preform formed by laminating a plurality of sheets of a composite material containing continuous reinforcing fibers and a thermoplastic resin as a matrix resin, wherein adjacent sheets of the composite material in the thickness direction have joints and non-joined parts and are joined at the joints, and in each of the composite material sheets, the ratio of the total area of ​​the joints on the front and back surfaces to the total area of ​​the non-joined parts on the front and back surfaces (total area of ​​joints / total area of ​​non-joined parts) is 5 / 95 to 40 / 60, where the sum of the total area of ​​the joints and the total area of ​​the non-joined parts is 100. [2] The laminated preform has a plurality of joints in each of the composite material sheets, and the joint area of ​​each joint is 1 mm ２ Over 400mm ２ [3] The laminated preform according to [1], wherein the bonding strength of one of the bonded portions is 1 MPa or more and 30 MPa or less. [4] The laminated preform according to [2] or [3], wherein the plurality of bonded portions are evenly distributed within the surface of the sheet-like composite material. [5] The laminated preform according to any one of [1] to [4], wherein the laminated preform is shaped and the shaped portion does not have any bonded portions. [6] The laminated preform according to any one of [1] to [5], wherein the void content of the sheet-like composite material is 5% or less. [7] The laminated preform according to any one of [1] to [6], wherein the thickness of the sheet-like composite material is 10 μm or more and 500 μm or less. [8] The laminated preform according to any one of [1] to [7], wherein the continuous reinforcing fibers are carbon fibers. [9] In the sheet-like composite material, the thermoplastic resin is at least one selected from polypropylene resin, polyamide resin, polyphenylene sulfide resin, polyether ether ketone resin, polyether ketone ketone resin, and aromatic polyether ketone resin. The laminated preform according to any one of [1] to [8].

[0010] According to the present invention, it is possible to provide a fiber-reinforced thermoplastic resin laminate preform that is excellent in handleability and shapeability.

[0011] 10 is a development view illustrating an example of a laminated preform in which four sheets of sheet-like composite material are laminated; 11 is a development view illustrating another example of a laminated preform in which four sheets of sheet-like composite material are laminated; 12 is a schematic cross-sectional view of an example of a laminated preform in which four sheets of sheet-like composite material are laminated; 13 is a diagram illustrating a method for measuring the maximum height of wrinkles in an L-shaped bent molded product; 14 is a schematic top view of a sheet-like composite material illustrating an example of the arrangement of joints; 15 is a schematic top view of a sheet-like composite material illustrating another example of the arrangement of joints, (a) is an example in which the arrangement direction of the joints is orthogonal, (b) is an example in which the arrangement direction of the joints forms an angle of 60 °. 16 is an example of the shape of a shaped molded product, (a) is a perspective view, (b) is a three-sided view, and (c) is a view emphasizing the curved surface-imparted portion. 17 is a top view showing an example of the arrangement of joints in the laminated preform of the present invention to obtain the molded product of FIG. 10; 18 is a diagram illustrating a T-shaped hat-shaped molded product molded in Example 7, (a) is a perspective view, and (b) is a dimensional drawing.

[0012] The laminated preform according to the present invention is a laminated preform in which a plurality of sheet-like composite materials containing continuous reinforcing fibers and a thermoplastic resin as a matrix resin are laminated together.

[0013] Here, a sheet-like composite material containing continuous reinforcing fibers and a thermoplastic resin as a matrix resin is a sheet-like composite material in which continuous reinforcing fibers are embedded within the matrix resin, and the matrix resin is reinforced by the reinforcing fibers. The continuous reinforcing fibers can take the form of a plurality of multifilaments arranged in one direction for reinforcement, or a woven fabric or braid. Here, "continuous" refers to reinforcing fibers with a length of at least 100 mm or more, and it is preferable to use single fibers with a length of 100 m or more. Furthermore, it is preferable that the single fibers contained in the bundle of reinforcing fibers do not have any cut portions within the sheet-like composite sheet.

[0014] In the present invention, glass fibers, organic fibers, metal fibers, etc. can be used as reinforcing fibers, but carbon fibers are preferred to obtain a lightweight sheet-shaped composite material with excellent strength and rigidity. The type of carbon fiber used can be selected based on its strength and elastic modulus depending on the application and required properties, but polyacrylonitrile-based carbon fibers are preferred from the viewpoint of mechanical properties.

[0015] In the present invention, it is important to use a thermoplastic resin as the matrix resin because it has excellent characteristics such as recyclability, a short molding cycle, post-processing properties such as welding, and improved impact resistance of molded products. Examples of thermoplastic resins that can be used depending on the required performance include polypropylene resin, polyamide resin, polyphenylene sulfide (PPS) resin, polyether ether ketone (PEEK) resin, polyether ketone ketone (PEKK) resin, and aromatic polyether ketone (PAEK) resin. Among these, at least one resin selected from the group consisting of PPS resin, PEEK resin, PEKK resin, and PAEK resin, which also have excellent heat resistance and flame retardancy, is preferably used. The thermoplastic resin used as the matrix resin may be a mixture of multiple resins.

[0016] Furthermore, in the laminated preform of the present invention, a plurality of sheet-like composite materials are used, and the reinforcing fibers and the thermoplastic resin matrix resin of each sheet-like composite material may be the same as or different from those of other sheet-like composite materials in terms of the composition of the matrix resin, the type and arrangement of the reinforcing fibers.

[0017] The laminated preform of the present invention is a laminated preform formed by laminating multiple sheets of sheet-like composite material. Here, "multiple sheets" means two or more sheets. When using a sheet-like composite material (conveniently referred to as a "unidirectional reinforced sheet") reinforced in one direction by arranging multiple multifilaments as reinforcing fibers, in order to uniformly reinforce the fiber direction, the laminated preform can be formed by laminating the sheets so that the orientation direction of the reinforcing fibers is shifted by 45° relative to the orientation direction of the reinforcing fibers of adjacent unidirectional reinforced sheets. For example, when the orientation direction of the reinforcing fibers of the unidirectional reinforced sheet laminated on top is 0°, the orientation direction of the reinforcing fibers of the next unidirectional reinforced sheet is +45°, the orientation direction of the reinforcing fibers of the next unidirectional reinforced sheet is +90°, and the orientation direction of the reinforcing fibers of the next unidirectional reinforced sheet is -45°. This is a preferred embodiment. Such an embodiment can be expressed as a laminate configuration of the composite material such as [0° / 45° / 90° / -45°], and a preferred embodiment can be exemplified by a laminate of eight unidirectional reinforcing sheets in such a manner that the orientation directions of the reinforcing fibers are symmetrical in the thickness direction, such as [0° / 45° / 90° / -45° / -45° / 90° / 45° / 0°], for the purpose of suppressing the occurrence of warpage in the laminated preform.

[0018] In the multiple sheet-like composite materials of the laminated preform of the present invention, it is important that adjacent sheet-like composite materials in the thickness direction have a joint and a non-joined portion and are joined at the joint. That is, adjacent sheet-like composite materials are not joined over the entire surface (note that sheet-like composite materials have a front and a back surface, but when describing the joined surface, the joined surface will be referred to as the front surface). A specific explanation will be given using FIG. 1. FIG. 1 shows an example of a laminated preform of the present invention in which four sheet-like composite materials are stacked. Note that the figure shows gaps between the sheet-like composite materials to facilitate understanding of the stacked state. The sheet-like composite material has a joint portion, indicated by reference numeral 3, where adjacent sheet-like composite materials are joined, and a non-joined portion, indicated by reference numeral 4. The joint portion can be formed by welding using a heating means such as a heater or laser. It is also possible to form the joint portion by applying an adhesive to the area to be joined, but using an adhesive to join may not result in sufficient bonding, which is not preferable as it may lead to a decrease in the performance of the laminated preform. For this reason, it is preferable to form the joint portion by welding.

[0019] It is important that the ratio (AA / NA) of the total area (AA) of the bonded portions on the front and back surfaces to the total area (NA) of the non-bonded portions on the front and back surfaces of each sheet-like composite material is 5 / 95 to 40 / 60, where the sum of the total area of ​​the bonded portions and the total area of ​​the non-bonded portions is 100. By setting AA / NA in this range, the laminated layers of the laminated preform will not collapse and fall off. Furthermore, when the laminated preform is shaped during press molding, it can be well adapted to bending deformation and drawing deformation according to the desired shape. AA / NA is more preferably 10 / 90 to 35 / 65, and even more preferably 15 / 85 to 30 / 70.

[0020] The area and ratio of the bonded and non-bonded portions can be calculated by observing the laminated preform with X-ray CT. Specifically, one method is to quantify the area by image analysis, using contrast between the gaps between the sheets in the non-bonded portions and the bonded portions. Another method involves peeling a sheet-like composite material from the laminated preform, observing the peeled surface, and quantifying the area by image analysis. A simple method involves observing the cross section of the laminated preform, measuring the length observed as the bonded portion between adjacent sheets of composite material, and the length observed as the non-bonded portion, i.e., the portion that is not a bonded portion. This measurement is performed at several cross sections, at least five or more locations, and the arithmetic average of the length ratio is used to determine the area ratio. Figure 3 shows a cross section of an example of a laminated preform made of four laminated sheets of composite material. Note that this figure shows the bonding at the bonded portion in a schematic manner to facilitate understanding. The portion indicated by La in Figure 3 is the joint where adjacent sheet-like composite materials are joined, and the length of the joint ΣLa is the sum of all the lengths of the joints on the front and back surfaces of each sheet-like composite material in the cross section of the laminated preform (La in the example of Figure 3). The portion indicated by Lb is a non-joined portion where adjacent sheet-like composite materials are not joined, and the length of the non-joined portion ΣLb is the sum of all the lengths of the joints on the front and back surfaces of each sheet-like composite material in the cross section of the laminated preform (Lb in the example of Figure 3). The ratio of ΣLa to ΣLb is calculated by setting ΣLa + ΣLb to 100, and the area ratio of the joints to the non-joined portions is determined. The cross-sectional range of the laminated preform to be observed can be, for example, 10 mm in the thickness direction and 100 mm in the length direction.

[0021] Furthermore, it is preferable that the laminated preform of the present invention has a plurality of bonded portions in each sheet-like composite material. In the example of the laminated preform shown in Figure 2, the bonded portions 3 are arranged so as to overlap, resulting in the presence of a single bonded portion. On the other hand, there are a plurality of independent non-bonded portions 5 surrounded by bonded portions. In this embodiment, when press-molding the laminated preform, there is a possibility that gas will not completely escape from the non-bonded portions 5 surrounded by bonded portions 3 and remain as voids. Therefore, it is preferable that the number of non-bonded portions surrounded by bonded portions is small, and more preferably, there are no non-bonded portions.

[0022] In the laminated preform of the present invention, when each sheet-like composite material has a plurality of joints, the joint area of ​​each joint is 1 mm ２ Over 400mm ２ By setting the thickness within this range, the lamination of the laminated preform will not collapse and fall off, and when the laminated preform is shaped during press molding, it can be well adapted to bending deformation and drawing deformation according to the shape of the intended molding, and further, when press molding, internal air bubbles are expelled, making it difficult for voids to remain in the molded product, which is preferable. The bonding area of ​​each bonding portion is more preferably 5 mm ２ More than 200 mm ２ Less than 10 mm, more preferably ２ More than 100 mm ２ The area of ​​the bonded portion can be measured by observing the laminated preform with an X-ray CT to create contrast between the gaps between the sheets in the non-bonded portion and the bonded portion, and quantifying the area by image analysis, or by peeling off the sheet-like composite material from the laminated preform, observing the peeled surface, and quantifying the area by image analysis.

[0023] In the laminated preform of the present invention, the sheet-like composite material preferably has a plurality of joints, and the joint strength of each joint is preferably 1 MPa to 30 MPa. By setting the joint strength within this range, the laminated state of the laminated preform is sufficiently maintained and it does not collapse and fall off, which is preferable. Furthermore, in order to easily follow bending deformation and drawing deformation according to the desired shape during press molding while sufficiently maintaining the laminated state, the joint strength of each joint is more preferably 2 MPa to 20 MPa, and even more preferably 3 MPa to 10 MPa. The joint strength can be measured by adhering a laminated preform cut out at a portion including the joint to a metal jig with an adhesive and conducting a peel test.

[0024] Furthermore, in the laminated preform of the present invention, when the sheet-like composite material has a plurality of bonding portions, it is preferable that the bonding portions are uniformly distributed in the plane. A uniform distribution state is preferable because the laminated state of the laminated preform is sufficiently maintained and it does not collapse and fall off, and it is easy to follow bending deformation and drawing deformation according to the shape of the target molding during press molding. Here, "evenly distributed bonded portions" means that, assuming a circle with the smallest radius (the radius of this circle is "radius r") passing from the center of gravity of a bonded portion to the center of gravity of an adjacent bonded portion on the surface of the sheet-like composite material, at all bonded portions except for those forming the outer periphery of the bonded portion (when no bonded portion is provided in the shaped portion, as described below, the bonded portion adjacent to the shaped portion is considered to be a bonded portion on the outer periphery), there are two or more center of gravity of other bonded portions within a ring bounded by a circle with a radius of r x 0.95 and a circle with a radius of r x 1.05, preferably a ring bounded by a circle with a radius of r x 0.99 and a circle with a radius of r x 1.01. The number of center of gravity of other bonded portions that satisfy this condition is 4 in the example of Figure 5, 2 in the example of Figure 6(a), and 6 in the example of Figure 6(b). It is assumed that the centers of gravity of all the joints forming the periphery of the joint group are located within the area of ​​the ring from the other joints. That is, in the case of the distribution of joints shown in Fig. 5, when d1 to d4 are equal (square lattice), joints B to D are joints included in the area of ​​the ring when viewed from joint A. In the case of the distribution of joints shown in Fig. 6(a), when the distances (distances d) between joints in the short side direction of the sheet are equal and the distance between joints in the long side direction of the sheet is longer than the distance d between joints between the short sides, adjacent joints in the short side direction are joints included in the ring. In the case of the distribution of joints shown in Fig. 6(b), when the distances (distances d) between adjacent joints are all equal, adjacent joints are located at the vertices of a regular hexagon.

[0025] Furthermore, when the number of bonded points included in the ring is two and the two bonded points and the base bonded point are on a straight line (for example, when the bonded points are distributed in a rectangular lattice pattern ( FIG. 6( a))), when a circle having the second longest length among the circles passing through the center of gravity of a certain bonded point and the center of gravity of an adjacent bonded point (the radius of this circle is taken as "radius r'") is imagined, it is preferable that at all bonded points on the surface of the sheet-like composite material except for the bonded points forming the outer periphery of the group of bonded points, two or more centers of gravity of other bonded points exist in a region of a ring surrounded by a circle of [radius r' x 0.95] and a circle of [radius r' x 1.05] from the center of gravity of the bonded point, preferably a ring surrounded by a circle of [radius r' x 0.99] and a circle of [radius r' x 1.01].

[0026] The term "evenly distributed" means that 95% or more of all the joints satisfy the above relationship, preferably 99% or more, and most preferably all the joints satisfy the above relationship. In this case, the joints for determining r or r' are selected from the joints that satisfy the above relationship.

[0027] Furthermore, since the laminate preform of the present invention is intended to be shaped and used to produce molded articles, it is preferable that the shaped portion of the laminate preform (the portion in the laminate preform referred to as the "curved surface shape imparted portion") when shaped does not have a joint in order to better express the shapeability during molding. This is because it is preferable that the portion where the curved surface shape of the molded article exists minimize interference between the sheet-like composite materials of the laminate preform in order to favorably shape the laminate preform during molding. Curved surface shapes imparted during shaping include single curved surfaces (curved surfaces with a Gaussian curvature of 0) typified by bent shapes, and double curved surfaces (with positive or negative Gaussian curvature) typified by box shapes and saddle shapes. Here, the portion corresponding to the curved surface shape imparted portion is understood to be a region where the direction of the normal vector at a point on the surface of the molded article changes continuously. Specific examples of curved surface shapes are shown in Figure 7. This example is a T-shaped hat shape, and the portion corresponding to the curved surface shape imparted portion in this shape is shaded in black (see Figure 7(c)). 8 shows an example of a laminated preform viewed from vertically above the lamination surface, which does not include the joints in the area corresponding to the curved surface of the T-shaped hat-shaped molded product. In this example, the laminated preform does not include any joints in the area surrounded by the dashed line, which includes the curved surface of the T-shaped molded product, ensuring good shaping properties.

[0028] The sheet-like composite material used in the present invention can be obtained, for example, by impregnating parallel-aligned reinforcing fibers with a thermoplastic resin as a matrix resin. Examples of resin impregnation methods include the film method, in which a film-like thermoplastic resin is melted and pressurized to impregnate the reinforcing fiber bundle with the thermoplastic resin; the commingle method, in which a fibrous thermoplastic resin is blended with the reinforcing fiber bundle, and then the fibrous thermoplastic resin is melted and pressurized to impregnate the reinforcing fiber bundle with the thermoplastic resin; the powder method, in which a powdered thermoplastic resin is dispersed into the gaps between the fibers in the reinforcing fiber bundle, and then the powdered thermoplastic resin is melted and pressurized to impregnate the reinforcing fiber bundle with the thermoplastic resin; and the pultrusion method, in which the reinforcing fiber bundle is immersed in the molten thermoplastic resin and then pressurized to impregnate the reinforcing fiber bundle with the thermoplastic resin.

[0029] Furthermore, from the viewpoint of preventing voids from remaining in the molded product during press molding, the void content of the sheet-like composite material is preferably 5% or less. If voids remain in the sheet-like composite material, the portion where the voids exist may expand after molding, resulting in defects such as wrinkles in the molded product. It is more preferable that the void content be 3% or less, and even more preferably 1% or less. The void content can be determined by observing the cross section of the sheet-like composite material, measuring the area of ​​the void-containing portion by image analysis, and dividing the area of ​​the void-containing portion by the cross-sectional area of ​​the sheet-like composite material. Effective methods for reducing the void content include increasing the pressure, increasing the melting temperature of the thermoplastic resin to reduce the melt viscosity, and extending the time for resin impregnation.

[0030] The thickness of the sheet-like composite material used in the present invention is preferably 10 μm or more and 500 μm or less. By setting it in this range, the thickness of the laminated preform can be adjusted without increasing the number of sheets of the sheet-like composite material required to produce a laminated preform of a predetermined thickness, and further, when the laminated preform is press-molded, it is preferable because it can easily follow bending deformation and drawing deformation according to the desired shape. The thickness of the sheet-like composite material is more preferably 50 μm or more and 400 μm or less, and even more preferably 100 μm or more and 300 μm or less.

[0031] The present invention will be explained in more detail below with reference to examples, but the present invention should not be construed as being limited to the descriptions in the examples section.

[0032] The obtained laminated preform was subjected to the following evaluations, and the results are summarized in Tables 1 and 2.

[0033] (Bonding strength of laminated preform joints) A 20 mm square sample including one joint was cut out from the prepared laminated preform, metal blocks were attached to the front and back sides, and the metal blocks were pulled to perform a peel test on the laminated preform. The maximum load during the test was measured by observing the fracture surface after the test, and the bonding area was calculated by dividing the maximum load by the bonding area. Note that if a sample of 20 mm square size cannot be cut out, for example, because the distance between adjacent joints is less than 20 mm, a sample with the largest area including one joint was cut out.

[0034] (Evaluation of transportability) The produced laminated preform was allowed to freely drop from a height of 2 m with a corner facing downwards, and this action was repeated five times, and the state of the laminated preform was visually observed and evaluated using the following four levels: A indicates no peeling or falling off of the sheet-like composite material, B indicates partial peeling but no falling off, C indicates peeling but no falling off, and D indicates peeling and falling off, with ratings A, B, and C being considered to be good results in transportability.

[0035] (Evaluation of formability) The prepared preform was heated to 340 ° C. with an IR heater and transferred to an L-shaped mold with an inner corner R of 3 mm, the temperature of which was adjusted to 150 ° C., and press-molded at a pressure of 5 MPa for 10 minutes to remove the molded product. The cross section of the obtained molded product near the L-shaped bent portion was observed to check for the presence or absence of wrinkles. For those with wrinkles, the maximum height at which the wrinkles reached their maximum height was measured and evaluated on the following four levels. A was assigned for no wrinkles, B for a maximum wrinkle height of less than 1 mm, C for a maximum wrinkle height of 1 mm or more but less than 2 mm, and D for a maximum wrinkle height of 2 mm or more. Evaluations A, B, and C were deemed acceptable. Figure 4 shows an example of measuring the maximum wrinkle height of an L-shaped bent molded product. The maximum wrinkle height was measured on the cut surface, and the cutting positions were set at a total of three positions in the longitudinal direction of the L-shaped bent portion: the center between the ends and halfway from the center to the ends, and the maximum was designated as the maximum wrinkle height. The maximum height of the wrinkles was determined as the distance 7 between the surface of the preform and a plane horizontal to the surface and in contact with the apex of the wrinkles 6 .

[0036] (Void content) The cross section of the obtained molded article was observed to determine whether voids were present. If voids were present, the area of ​​the void portion was divided by the total measured cross-sectional area of ​​the molded article to calculate the void content. The measurement was carried out at three locations on the same cross section as used for the formability evaluation, with the location corresponding to the curved shape imparted portion being used as the measured cross-sectional area, and the average of the three locations was calculated, and the evaluation was made on the following four levels: A: a void content of less than 1%, B: a void content of 1% or more but less than 3%, C: a void content of 3% or more but less than 5%, and D: a void content of 5% or more. Note that A is the best.

[0037] (Example 1) Carbon fiber bundles: Toray Industries, Inc. ("Torayca" (registered trademark)) T700S-12K were continuously fed out in one direction and impregnated with polyphenylene sulfide ("Torelina" (registered trademark) manufactured by Toray Industries, Inc.) to obtain a sheet-like composite material (CFRP1) with a void content of 5%. The weight of the carbon fibers was 190 g / m. ２ The resulting composite sheet was cut into a 300 mm square piece, and the fiber orientation direction of the outermost layer was set to 0°, followed by 90° for the next layer, then 0° for the next layer, and so on, until a total of 15 sheets were laminated. ２ A circular heated metal iron was applied with a load of 300 g to weld the lattice points of the square lattice to produce a laminated preform. The welding point distance of the square lattice to be welded was adjusted so that the area ratio of the bonded portion to the non-bonded portion would be the value shown in Table 1.

[0038] Example 2 A laminated preform was produced in the same manner as in Example 1, except that the spacing between the bonded portions was changed to adjust the number of bonded portions per unit area, and the area ratio of the bonded portions to the non-bonded portions was set to 10 / 90.

[0039] Example 3 A laminated preform was produced in the same manner as in Example 1, except that the spacing between the bonded portions was changed to adjust the number of bonded portions per unit area, and the area ratio of the bonded portions to the non-bonded portions was set to 20 / 80.

[0040] Example 4 A laminate preform was produced in the same manner as in Example 3, except that the load when the heated metal iron was applied was changed to 1000 g.

[0041] (Example 5) The area per joint is 10 mm ２ A laminated preform was produced in the same manner as in Example 4, except that the above-mentioned

[0042] Example 6 A laminated preform was produced in the same manner as in Example 5, except that the same materials as in Example 1 were used, but a sheet-like composite material (CFRP2) with a void content of 1% was used.

[0043] (Example 7) A laminated preform was produced in the same manner as in Example 6. In this example, molding was carried out using a mold for a T-shaped hat-shaped molded article as shown in Fig. 9, and evaluation was carried out. However, the evaluation of formability was carried out by observing the cross section near the T-shaped part of the molded article.

[0044] Example 8 A laminated preform was produced in the same manner as in Example 7, except that a laminated preform was produced that did not include a joint at a location corresponding to the portion to be given a curved surface shape to the molded article, and evaluation was carried out.

[0045] Comparative Example 1 A laminated preform was produced in the same manner as in Example 1, except that no joints were provided. However, the sheet-like composite material peeled off, making it impossible to evaluate the formability.

[0046] Comparative Example 2 A laminated preform was produced in the same manner as in Example 1, except that the area ratio of the bonded portion to the non-bonded portion was set to 1 / 99.

[0047] Comparative Example 3 A laminated preform was produced in the same manner as in Example 1, except that the area ratio of the bonded portion to the non-bonded portion was set to 100 / 0.

[0048] Comparative Example 4 A laminated preform was produced in the same manner as in Example 1, except that the area ratio of the bonded portion to the non-bonded portion was set to 50 / 50.

[0049] The results are shown in Tables 1 and 2. In Example 1, a laminated preform with excellent transportability and shapability was obtained. In Example 2, in which the area ratio of the bonded portions to the non-bonded portions was adjusted to a more preferred range, the transportability of the laminated preform was improved. In Example 3, in which the area ratio of the bonded portions to the non-bonded portions was adjusted to an even more preferred range, the void content of the molded product was even better. In Example 4, in which the bonding strength of the bonded portions was adjusted to a preferred range by applying a heated metal iron with a load of 1000 g, the transportability was further improved. In Example 5, in which the area per bonded portion was adjusted to a preferred range, the shapability was further improved. In Example 6, the void fraction of the sheet-like composite material was set to 1%, which allowed the void content of the resulting molded product to be reduced.

[0050] As shown in Example 7, good results were obtained in terms of formability using the laminated preform of the present invention. Furthermore, as shown in Example 8, by using a laminated preform that did not include a joint at the portion corresponding to the curved surface shape imparted portion, the formability was further improved.

[0051] On the other hand, in Comparative Example 1, no bonded portions were provided, so the sheet-like composite material easily peeled off. In Comparative Example 2, in which the area ratio of bonded portions to non-bonded portions was 1 / 99, the sheet-like composite material also easily peeled off. In Comparative Example 3, in which the area ratio of bonded portions to non-bonded portions was 100 / 0, bonding was performed over the entire surface, which resulted in poor movement of the sheet-like composite material in the laminated preform and poor formability.

[0052]

[0053]

[0054] The laminated preform according to the present invention is a fiber-reinforced thermoplastic resin laminated preform that is excellent in handleability and shapeability, and can be suitably used for press molding or stamping molding.

[0055] 1: Laminated preform 2: Sheet-like composite material 3: Joint section 4: Non-joined section 5: Independent non-joined section surrounded by joint section 6: Wrinkles in molded product 7: Maximum wrinkle height of molded product

Claims

1. A laminated preform formed by laminating a plurality of sheets of a composite material containing continuous reinforcing fibers and a thermoplastic resin as a matrix resin, wherein adjacent sheets of the composite material in the thickness direction have joints and non-joined sections and are joined at the joints, and wherein, for each sheet of composite material, the ratio of the total area of ​​the joints on the front and back surfaces to the total area of ​​the non-joined sections on the front and back surfaces (total area of ​​joints / total area of ​​non-joined sections) is 5 / 95 to 40 / 60, where the sum of the total area of ​​the joints and the total area of ​​the non-joined sections is 100.

2. The laminated preform has a plurality of joints in each sheet-like composite material, and the joint area of ​​each joint is 1 mm ２ Over 400mm ２ 2. The laminate preform according to claim 1, wherein:

3. The laminated preform according to claim 2, wherein the bonding strength of one of the bonding portions is 1 MPa or more and 30 MPa or less.

4. The laminated preform according to claim 2, wherein the plurality of bonding portions are uniformly distributed within the surface of the sheet-like composite material.

5. The laminated preform according to claim 1, characterized in that the laminated preform is shaped and has no joints in the shaped portion.

6. The laminate preform according to claim 1, wherein the void content of said sheet-like composite material is 5% or less.

7. The laminate preform according to claim 1, wherein the thickness of said sheet-like composite material is 10 μm or more and 500 μm or less.

8. The laminate preform according to claim 1, wherein said continuous reinforcing fibers are carbon fibers.

9. The laminated preform according to claim 1, wherein in the sheet-like composite material, the thermoplastic resin is at least one selected from the group consisting of polypropylene resin, polyamide resin, polyphenylene sulfide resin, polyether ether ketone resin, polyether ketone ketone resin, and aromatic polyether ketone resin.

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