A multi-scale fiber-reinforced thermoplastic composite board and its manufacturing method

Abstract

A multi-scale fiber-reinforced thermoplastic composite plate and its manufacturing method, comprising an upper surface layer and a lower surface layer formed by at least one layer of unidirectional continuous fiber-reinforced thermoplastic composite prepreg, and an intermediate layer connected between the upper surface layer and the lower surface layer and formed by at least one layer of discontinuous long fiber-reinforced composite slices; the layup structure of one or more layers of unidirectional continuous fiber-reinforced thermoplastic composite prepregs in the upper surface layer and the layup structure of one or more layers of unidirectional continuous fiber-reinforced thermoplastic composite prepregs in the lower surface layer are in a mirror-symmetric structure; when the intermediate layer is formed by laying multiple layers of discontinuous long fiber-reinforced composite slices, the multiple layers of discontinuous long fiber-reinforced composite slices are in a mirror-symmetric structure, and in the direction from the surface of the plate to its core, the width and length of each layer of discontinuous long fiber-reinforced composite slices decrease in sequence. This plate has high strength, high rigidity, small porosity and high production efficiency.

Description

Technical Field

[0001] The present invention relates to a multi-scale fiber-reinforced thermoplastic composite plate and a manufacturing method thereof. Background Art

[0002] Fiber-reinforced thermoplastic composite plates have the characteristics of light weight, high stiffness, high toughness, and recyclability, and are widely used in many fields such as the automotive industry, aerospace, military, and electronics. As described in Chinese Patent CN109318509A for a discontinuous long-line-length fiber-reinforced thermoplastic composite compression molding preform, it includes slices made by cutting continuous fiber-reinforced thermoplastic composite prepreg sheets / yarns, and the slices are transported, mixed, spread, hot-pressed, cooled, and cut to form a compression molding preform. It has high tensile strength and bending strength in all directions, but its impact strength is not high and the porosity is large. Summary of the Invention

[0003] The present invention aims to provide a multi-scale fiber-reinforced thermoplastic composite plate with high impact strength, small porosity, and high production efficiency, and a manufacturing method thereof.

[0004] A multi-scale fiber-reinforced thermoplastic composite plate according to the present invention includes an upper surface layer and a lower surface layer formed by at least one layer of unidirectional continuous fiber-reinforced thermoplastic composite prepreg sheets, and an intermediate layer connected between the upper surface layer and the lower surface layer and formed by at least one layer of discontinuous long-line-length fiber-reinforced composite slices; the ply structure of one or more layers of unidirectional continuous fiber-reinforced thermoplastic composite prepreg sheets in the upper surface layer is mirror-symmetric with the ply structure of one or more layers of unidirectional continuous fiber-reinforced thermoplastic composite prepreg sheets in the lower surface layer; when the intermediate layer is formed by laying multiple layers of discontinuous long-line-length fiber-reinforced composite slices, the multiple layers of discontinuous long-line-length fiber-reinforced composite slices are mirror-symmetric, and in the direction from the surface of the plate to its core, the width and length of each layer of discontinuous long-line-length fiber-reinforced composite slices decrease in sequence.

[0005] A manufacturing method of a multi-scale fiber-reinforced thermoplastic composite plate according to the present invention includes the following steps:

[0006] 1) Preparation of the upper surface layer and the lower surface layer: An extrusion die extrudes molten resin and coats it on unidirectional continuous fibers passing through the extrusion die, so that the unidirectional continuous fibers are fully impregnated, and then cooled to form unidirectional continuous fiber-reinforced thermoplastic composite prepreg sheets; when there are multiple layers of unidirectional continuous fiber-reinforced thermoplastic composite prepreg sheets in the upper surface layer and the lower surface layer respectively, after the multiple layers of unidirectional continuous fiber-reinforced thermoplastic composite prepreg sheets are laid in a layered manner at a specified laying angle, they are hot-pressed and compounded to form the upper surface layer and the lower surface layer;

[0007] 2) Preparation of the intermediate layer: The melt resin is extruded through an extrusion die head and coated on the unidirectional continuous fibers or unidirectional continuous fiber bundles passing through the extrusion die head, so that the unidirectional continuous fibers or unidirectional continuous fiber bundles are fully impregnated. Subsequently, it is cooled and made into a prepreg sheet of unidirectional continuous fiber reinforced thermoplastic resin composite or a prepreg yarn of unidirectional continuous fiber reinforced thermoplastic resin composite. Then, the prepreg sheet of unidirectional continuous fiber reinforced thermoplastic resin composite or the prepreg yarn of unidirectional continuous fiber reinforced thermoplastic resin composite is cut or severed online or by winding and unwinding offline to make discontinuous long fiber length fiber reinforced composite slices. When there are multiple layers of discontinuous long fiber length fiber reinforced composite slices in the intermediate layer, after the multiple layers of discontinuous long fiber length fiber reinforced composite slices are laid and stacked, they are made into the intermediate layer after hot pressing, compounding and cooling;

[0008] 3) Lay half of the intermediate layer on the lower surface layer and the other half of the intermediate layer on the upper surface layer, and evenly sprinkle fibers on the surface of the intermediate layer on the upper surface layer or the surface of the intermediate layer on the lower surface layer that has been laid through at least one spreading head. After hot pressing and cooling, it is cut or wound to form a semi-finished product of a multi-scale fiber reinforced thermoplastic composite board;

[0009] 4) Stack the two semi-finished products obtained in step 3) and form the finished product of the multi-scale fiber reinforced thermoplastic composite board after hot pressing and cooling.

[0010] For a multi-scale fiber reinforced thermoplastic composite board and its manufacturing method according to the present invention, since the laying structure of one or more layers of unidirectional continuous fiber reinforced thermoplastic resin composite prepreg sheets in the upper surface layer and the laying structure of one or more layers of unidirectional continuous fiber reinforced thermoplastic resin composite prepreg sheets in the lower surface layer are in a mirror-symmetrical structure, when the intermediate layer is formed by laying multiple layers of discontinuous long fiber length fiber reinforced composite slices, the multiple layers of discontinuous long fiber length fiber reinforced composite slices are in a mirror-symmetrical structure, and in the direction from the surface of the board to its core, the width and length of each layer of discontinuous long fiber length fiber reinforced composite slices decrease in sequence. Combined with evenly sprinkling fibers during the production process, the fibers can interpenetrate with each other to fill the voids, effectively reducing the porosity, making the fibers evenly distributed in all directions, enabling the board to greatly improve the impact strength on the premise of ensuring sufficient tensile strength, bending strength and rigidity, and making the mechanical properties of the board in all directions maintain uniformity; and the fiber length in the intermediate layer is retained relatively long, effectively ensuring the dimensional stability of the product and reducing the warping risk of secondary processing on the premise of ensuring mechanical strength and interlayer strength; and the above processing method has low production cost and high production efficiency. Brief Description of the Drawings

[0011] Figure 1 It is a schematic exploded view of the present invention.

[0012] Figure 2 This is a processing step diagram of the semi-finished product of the present invention. Detailed implementation mode

[0013] A multi-scale fiber-reinforced thermoplastic composite material plate, as Figure 1 shown, includes an upper surface layer 1 and a lower surface layer 2 formed by at least one layer of unidirectional continuous fiber-reinforced thermoplastic composite prepreg sheets. An intermediate layer 3 formed by at least one layer of discontinuous long fiber length fiber-reinforced composite material slices is connected between the upper surface layer 1 and the lower surface layer 2; the ply structure of one or more layers of unidirectional continuous fiber-reinforced thermoplastic composite prepreg sheets in the upper surface layer 1 and the ply structure of one or more layers of unidirectional continuous fiber-reinforced thermoplastic composite prepreg sheets in the lower surface layer 2 are in a mirror-symmetrical structure; when the intermediate layer 3 is formed by laying multiple layers of discontinuous long fiber length fiber-reinforced composite material slices, the multiple layers of discontinuous long fiber length fiber-reinforced composite material slices are in a mirror-symmetrical structure, and in the direction from the surface of the plate to its core, the width and length of each layer of discontinuous long fiber length fiber-reinforced composite material slices decrease in sequence. The ply structure of the multi-scale fiber-reinforced thermoplastic composite material plate is divided into [A / B / A’] ns or [A / BC…X X…CB / A’] ns and other symmetrical structure forms. A and A’ respectively represent the upper surface layer and the lower surface layer, while BC…X X…CB represents the intermediate layer 3 formed by discontinuous long fiber length fiber-reinforced composite material slices. It can also be seen from the above ply structure formula that when the intermediate layer 3 is formed by laying multiple layers of discontinuous long fiber length fiber-reinforced composite material slices, the multiple layers of discontinuous long fiber length fiber-reinforced composite material slices are in a mirror-symmetrical structure; the ply structure of one layer of unidirectional continuous fiber-reinforced thermoplastic composite prepreg sheet in the upper surface layer 1 and the ply structure of one layer of unidirectional continuous fiber-reinforced thermoplastic composite prepreg sheet in the lower surface layer 2 are in a mirror-symmetrical structure. For example, both the upper surface layer 1 and the lower surface layer 2 are laid in the 0° direction; and the ply structure of multiple layers of unidirectional continuous fiber-reinforced thermoplastic composite prepreg sheets in the upper surface layer 1 and the ply structure of multiple layers of unidirectional continuous fiber-reinforced thermoplastic composite prepreg sheets in the lower surface layer 2 are in a mirror-symmetrical structure. For example, if there are two layers of unidirectional continuous fiber-reinforced thermoplastic composite prepreg sheets in both the upper surface layer 1 and the lower surface layer 2, the upper surface layer 1 can be laid in the 0° / 90° direction, while the lower surface layer 2 can be laid in the 90° / 0° direction, and vice versa; in addition, the n in the lower right corner of the above ply structure represents the unit cycle number, that is, the cycle number of the ply structure. According to the required thickness of the plate, the cycle number of the ply structure is set, and n≥1.

[0014] When the intermediate layer 3 is formed by laying multiple layers of discontinuous long-fiber-reinforced composite material slices, at least one layer of unidirectional continuous fiber-reinforced thermoplastic composite material prepreg sheet 4 can also be provided at the central position of the intermediate layer 3 formed by the multiple layers of discontinuous long-fiber-reinforced composite material slices; when there are multiple layers of unidirectional continuous fiber-reinforced thermoplastic composite material prepreg sheets at the central position of the intermediate layer 3, the ply structure of the multiple layers of unidirectional continuous fiber-reinforced thermoplastic composite material prepreg sheets is a mirror-symmetric structure; one layer or multiple layers of unidirectional continuous fiber-reinforced thermoplastic composite material prepreg sheets 4 at the central position of the intermediate layer 3 divide the intermediate layer 3 into left and right parts, and the left and right parts of the intermediate layer 3 are mirror-symmetric structures. That is, the ply structure of the multi-scale fiber-reinforced thermoplastic composite material plate can also be divided into [A / BC…X A0 X …CB / A’] ns Or [A / B A0B / A’] ns And other symmetric structural forms. A0 represents one layer or multiple layers of unidirectional continuous fiber-reinforced thermoplastic composite material prepreg sheets at the central position of the intermediate layer. The laying methods of one layer or multiple layers of unidirectional continuous fiber-reinforced thermoplastic composite material prepreg sheets can be laying methods such as 0°, 0° / 90° / 0°, 90° / 0° / 90°, or 0° / 90° / 90° / 0°.

[0015] The width of the discontinuous long-fiber-reinforced composite material slice is 2 mm to 30 mm, the length is 5 mm to 200 mm, and the slice angle is 0° < θ ≤ 90°.

[0016] The unidirectional continuous fiber-reinforced thermoplastic composite material prepreg sheet is composed of unidirectional continuous fibers and resin. Based on the total weight of the unidirectional continuous fiber-reinforced thermoplastic composite material prepreg sheet, the weight percentage of the unidirectional continuous fibers is 40 wt% to 80 wt%; the discontinuous long-fiber-reinforced composite material slice is formed by compounding unidirectional continuous fibers or unidirectional continuous fiber tows and resin and then cutting or slicing. Based on the total weight of the discontinuous long-fiber-reinforced composite material slice, the weight percentage of the reinforcing fibers is 20 wt% to 90 wt%.

[0017] The unidirectional continuous fibers or unidirectional continuous fiber tows are carbon fibers or glass fibers, etc.

[0018] The resin is formed by combining thermoplastic resin, additives, and fillers in any ratio.

[0019] The thermoplastic resin is one or more of PE, PP, PA, PET, ABS, or PC combined in any ratio.

[0020] The additives are one or more of compatibilizers, antioxidants, lubricants, or ultraviolet stabilizers combined in any ratio.

[0021] The filler is one or more of silicone masterbatch, calcium carbonate, mica powder or color powder in any ratio combination.

[0022] A method for manufacturing a multi-scale fiber reinforced thermoplastic composite board, such as Figure 2As shown, it includes the following steps: (1) Preparation of the upper surface layer and the lower surface layer: The melt resin is extruded from an extrusion die head and coated on the unidirectional continuous fibers passing through the extrusion die head, so that the unidirectional continuous fibers are fully impregnated, and then cooled to form a unidirectional continuous fiber-reinforced thermoplastic composite prepreg sheet. When there are multiple layers of unidirectional continuous fiber-reinforced thermoplastic composite prepreg sheets on the upper surface layer and the lower surface layer respectively, after the multiple layers of unidirectional continuous fiber-reinforced thermoplastic composite prepreg sheets are laid in a layered manner at a specified laying angle, they are hot-pressed and compounded to form the upper surface layer and the lower surface layer; (2) Preparation of the intermediate layer: The melt resin is extruded from an extrusion die head and coated on the unidirectional continuous fibers passing through the extrusion die head or the unidirectional continuous fiber tow, so that the unidirectional continuous fibers or the unidirectional continuous fiber tow are fully impregnated, and then cooled to form a unidirectional continuous fiber-reinforced thermoplastic resin composite prepreg sheet or a unidirectional continuous fiber-reinforced thermoplastic resin composite prepreg yarn. Then, the unidirectional continuous fiber-reinforced thermoplastic resin composite prepreg sheet or the unidirectional continuous fiber-reinforced thermoplastic resin composite prepreg yarn is cut or severed online or by winding offline to form a discontinuous long-line-length fiber-reinforced composite slice. When there are multiple layers of discontinuous long-line-length fiber-reinforced composite slices in the intermediate layer, after the multiple layers of discontinuous long-line-length fiber-reinforced composite slices are stacked and laid, they are hot-pressed, compounded and cooled to form the intermediate layer; (3) Lay half of the intermediate layer (i.e., BC…X) on the lower surface layer and the other half of the intermediate layer (i.e., BC…X) on the upper surface layer, and evenly sprinkle fibers on the surface of the intermediate layer 3 on the upper surface layer or the surface of the intermediate layer 3 on the lower surface layer that has been laid through at least one spreading head 5. After hot pressing and cooling, it is cut or wound to form a semi-finished product of a multi-scale fiber-reinforced thermoplastic composite board. Among them, the sprinkled fibers can be short fibers, long fibers, or a mixture of short fibers and long fibers. By evenly sprinkling fibers, the voids on the intermediate layer can be filled to the greatest extent, and the porosity can be reduced to the greatest extent. And the spreading head 5 can have one, two, three, four, etc., and is added according to actual production needs; (4) Stack the two semi-finished products obtained in step (3) and form a finished product of a multi-scale fiber-reinforced thermoplastic composite board after hot pressing and cooling. When there is at least one layer of unidirectional continuous fiber-reinforced thermoplastic composite prepreg sheet at the center position of the intermediate layer of the finished product of the multi-scale fiber-reinforced thermoplastic composite board, in step (4), before the finished product is hot-pressed, first lay one or more layers of unidirectional continuous fiber-reinforced thermoplastic composite prepreg sheets on the surface of the intermediate layer on the upper surface layer or the surface of the intermediate layer on the lower surface layer, and then stack them according to step (4), and form a finished product of a multi-scale fiber-reinforced thermoplastic composite board after hot pressing, compounding and cooling.

[0023] The present invention will be further described below through specific embodiments. The following embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited by the following embodiments.

[0024] Example 1

[0025] In the multi-scale fiber-reinforced thermoplastic composite material plate of the present invention, the plate thickness is 3 mm. The upper surface layer and the lower surface layer are respectively formed by laying two layers of unidirectional continuous glass fiber-reinforced PP thermoplastic composite prepreg sheets. The upper surface layer is laid at 0° / 90°, and the lower surface layer is laid at 90° / 0°. Based on the total weight of the unidirectional continuous glass fiber-reinforced PP thermoplastic composite prepreg sheet, the weight percentage of the unidirectional continuous glass fiber is 70 wt%. The middle layer is formed by compounding six layers of discontinuous long-line fiber-reinforced composite material slices. Among them, the discontinuous long-line fiber-reinforced composite material slices are formed by compounding unidirectional continuous glass fibers or unidirectional continuous glass fiber tows and PP resin and then cutting or severing. Based on the total weight of the discontinuous long-line fiber-reinforced composite material slices, the weight percentage of the reinforcing fiber is 70 wt%. The lay-up structure of the upper surface layer, the lower surface layer, and the middle layer is [A / B / C / D / D / C / B / A']. In the direction from the surface of the plate to its core, the widths of the discontinuous long-line fiber-reinforced composite material slices of each layer B, C, and D are 20 mm, 9 mm, and 6 mm in sequence, the lengths are 30 mm, 15 mm, and 10 mm in sequence, and the slice angle is θ = 90°. Through the above manufacturing method, and by uniformly spreading fibers in sequence and hot-pressing and compounding, a multi-scale fiber-reinforced thermoplastic composite material plate is formed.

[0026] Comparative Example 1

[0027] A discontinuous long-line fiber-reinforced thermoplastic composite material compression molding preform with a plate thickness of 3 mm is formed by hot-pressing after mixing GF / PP slices and CF / PP prepreg yarn slices. Among them, based on the total weight of the unidirectional continuous glass fiber (GF)-reinforced PP thermoplastic composite prepreg sheet, the weight percentage of the unidirectional continuous glass fiber (GF) is 70 wt%. And based on the total weight of the CF-reinforced PP composite material slices, the weight percentage of the reinforcing fiber is 70 wt%. The lengths of the GF / PP slices and the CF / PP prepreg yarn slices are all 5 mm, 10 mm, 15 mm, and 35 mm. The width of the GF / PP slices is 12.7 mm, and the width of the CF / PP prepreg yarn slices is a mixture of 3.2 mm and 6.4 mm. All slice angles are θ = 90°.

[0028] Example 2

[0029] Based on Example 1, at the central position of the middle layer, there is an A0 layer formed by three layers of unidirectional continuous fiber-reinforced thermoplastic composite prepregs, and its layup pattern is 0° / 90° / 0°. The unidirectional continuous fiber-reinforced thermoplastic composite prepreg is composed of unidirectional continuous glass fibers and PP resin. Based on the total weight of the unidirectional continuous glass fiber-reinforced PP thermoplastic composite prepreg, the weight percentage of the unidirectional continuous glass fibers is 70wt%. The layup structures of the upper surface layer, the lower surface layer, and the middle layer are [A / B / C / D / A0 / D / C / B / A'], and the rest of the content is the same as that of Example 1.

[0030] Perform performance tests on Example 1 to Example 2 and Comparative Example 1, and the results are as follows:

[0031] Test item Unit Example 1 Comparative Example 1 Example 2 Porosity % 0.13 0.19 0.11 Izod impact strength - vertical direction <![CDATA[KJ / m 2 > 195 150 210 Izod impact strength - parallel direction <![CDATA[KJ / m 2 > 154 120 172

[0032] As can be seen from the above table, the porosity and impact resistance of the multi-scale fiber-reinforced thermoplastic composite board in the present invention are superior to those of the boards in the comparative examples.

Claims

1. A multi-scale fiber-reinforced thermoplastic composite plate, comprising an upper surface layer (1) and a lower surface layer (2) formed by multiple layers of unidirectional continuous fiber-reinforced thermoplastic composite prepregs, characterized in that: An intermediate layer (3) formed by multiple layers of discontinuous long-line-length fiber-reinforced composite material slices is connected between the upper surface layer (1) and the lower surface layer (2); the lay-up structure of the multi-layer unidirectional continuous fiber-reinforced thermoplastic composite prepreg in the upper surface layer (1) and the lay-up structure of the multi-layer unidirectional continuous fiber-reinforced thermoplastic composite prepreg in the lower surface layer (2) are in a mirror-symmetric structure; the multi-layer discontinuous long-line-length fiber-reinforced composite material slices are in a mirror-symmetric structure, and in the direction from the surface of the plate to its core, the width and length of each layer of discontinuous long-line-length fiber-reinforced composite material slices decrease in sequence. At least one layer of unidirectional continuous fiber-reinforced thermoplastic composite prepreg (4) is arranged at the central position of the intermediate layer (3) formed by the multi-layer discontinuous long-line-length fiber-reinforced composite material slices; when there are multiple layers of unidirectional continuous fiber-reinforced thermoplastic composite prepregs (4) at the central position of the intermediate layer (3), the lay-up structure of the multi-layer unidirectional continuous fiber-reinforced thermoplastic composite prepregs is in a mirror-symmetric structure; one layer or multiple layers of unidirectional continuous fiber-reinforced thermoplastic composite prepregs (4) at the central position of the intermediate layer (3) divide the intermediate layer (3) into upper and lower parts, and the upper and lower parts of the intermediate layer (3) are in a mirror-symmetric structure. The width of the discontinuous long-line-length fiber-reinforced composite material slice is 2 mm to 30 mm, the length is 5 mm to 200 mm, and the slice angle is 0° < θ < 90°. The discontinuous long-line-length fiber-reinforced composite material slice is formed by compounding unidirectional continuous fibers and resin and then cutting or severing.

2. The multi-scale fiber-reinforced thermoplastic composite material plate according to claim 1, wherein: The unidirectional continuous fiber-reinforced thermoplastic composite prepreg is formed by compounding unidirectional continuous fibers and resin. Based on the total weight of the unidirectional continuous fiber-reinforced thermoplastic composite prepreg, the weight percentage of the unidirectional continuous fibers is 40 wt% to 80 wt%; based on the total weight of the discontinuous long-line-length fiber-reinforced composite material slice, the weight percentage of the unidirectional continuous fibers therein is 20 wt% to 90 wt%.

3. The multi-scale fiber reinforced thermoplastic composite plate according to claim 2, wherein: The unidirectional continuous fiber is carbon fiber or glass fiber.

4. A multi-scale fiber-reinforced thermoplastic composite board according to claim 2, characterized in that: The resin is formed by combining thermoplastic resin, additives, and fillers in any ratio.

5. The multi-scale fiber-reinforced thermoplastic composite plate according to claim 4, characterized in that: The thermoplastic resin is one or more combinations in any ratio of PE, PP, PA, PET, ABS, or PC.

6. The multi-scale fiber-reinforced thermoplastic composite board according to claim 4, wherein: The additives are one or more combinations in any ratio of compatibilizer, antioxidant, lubricant, or ultraviolet stabilizer; the fillers are one or more combinations in any ratio of silicone masterbatch, calcium carbonate, mica powder, or color powder.

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