Fiber reinforced composite material and preparation method thereof

Abstract

The invention relates to a fiber reinforced composite material and a preparation method thereof, the composite material comprises a resin matrix and one or more layers of fiber fabrics arranged on the resin matrix, and the resin matrix comprises polyamide resin; wherein the polyamide resin has a viscosity of 1000 Pa.s or less under the conditions of 200 to 340 DEG C and a shear rate of 1 s <-1 >. According to the fiber reinforced composite material provided by the embodiment of the invention, the polyamide sheet and the fiber fabric with specific viscosity are adopted as the lamination raw materials, so that the composite material has excellent mechanical properties.

Description

Technical Field

[0001] This invention relates to composite materials, and more particularly to a fiber-reinforced polyamide composite material. Background Technology

[0002] With the continuous pursuit of lightweighting in industries such as automotive and aerospace, high-performance fiber-reinforced composite materials are widely favored due to their lightweight, high strength, high modulus, and designable structural characteristics. Compared to traditional thermosetting resin-based composite materials, thermoplastic resin-based composite materials not only have higher fracture toughness and longer storage time, but also exhibit shorter manufacturing cycles, reprocessability, and better chemical corrosion resistance.

[0003] In the industrial continuous production of polyamide continuous fiber composites, the high viscous resistance of the resin matrix during impregnation of continuous fibers is a significant problem. This viscous resistance not only affects the impregnation effect, increases porosity, and consequently affects the final mechanical properties of the composite material, but also reduces production efficiency, becoming a key factor restricting the production process and product quality. Summary of the Invention

[0004] To overcome at least one of the defects of the prior art, in a first aspect, one embodiment of the present invention provides a fiber-reinforced composite material, comprising a resin matrix and one or more layers of fiber fabric disposed on the resin matrix, wherein the resin matrix comprises a polyamide resin; wherein the polyamide resin is subjected to a shear rate of 1 s at a temperature of 200–340°C. -1 The viscosity under the given conditions is below 1000 Pa·s.

[0005] In a second aspect, one embodiment of the present invention provides a method for preparing the above-mentioned fiber-reinforced composite material, comprising molding a multilayer structure to obtain the fiber-reinforced composite material; wherein the multilayer structure comprises one or more polyamide sheets and one or more fiber fabrics.

[0006] Thirdly, one embodiment of the present invention provides the application of polyamide sheets in the preparation of fiber-reinforced composite materials, wherein the fiber-reinforced composite material is prepared by a lamination molding process, and the polyamide sheet is subjected to a shear rate of 1 second at 200–340°C. -1 The viscosity under the given conditions is below 1000 Pa·s.

[0007] Fourthly, one embodiment of the present invention provides a polyamide board comprising the fiber-reinforced composite material described above or the fiber-reinforced composite material prepared by the above preparation method.

[0008] Fifthly, one embodiment of the present invention provides a product comprising the polyamide board described above.

[0009] The fiber-reinforced composite material of one embodiment of the present invention achieves excellent mechanical properties by using polyamide sheets and fiber fabrics of specific viscosities as laminating materials. Attached Figure Description

[0010] The accompanying drawings are for illustrative purposes only and are not intended to limit the scope of the invention. Wherein:

[0011] Figure 1 This is a schematic diagram of the multilayer structure of Embodiment 1 of the present invention;

[0012] The annotations in the attached figures are explained as follows:

[0013] 100, First surface layer; 101, First intermediate layer; 102, Second intermediate layer; 200, Second surface layer. Detailed Implementation

[0014] Typical embodiments embodying the features and advantages of the present invention will be described in detail in the following description. It should be understood that the present invention can have various variations in different embodiments without departing from the scope of the present invention, and the description herein is for illustrative purposes only and not intended to limit the present invention.

[0015] One embodiment of the present invention provides a fiber-reinforced composite material, comprising a resin matrix and one or more layers of fiber fabric disposed in the resin matrix, wherein the resin matrix comprises polyamide resin; wherein the polyamide resin is subjected to a shear rate of 1 s at a temperature of 200–340°C. -1 The viscosity (or shear viscosity) under the specified conditions is below 1000 Pa·s.

[0016] In one embodiment, the fiber-reinforced composite material is obtained by laminating a multilayer structure, the multilayer structure including one or more polyamide sheets and one or more fiber fabrics, wherein one or more fiber fabrics are disposed between the multilayer polyamide sheets; after lamination, one or more polyamide sheets form a resin matrix, and one or more fiber fabrics are located in the resin matrix.

[0017] In one embodiment, the polyamide sheet is prepared by using a polyamide resin or a composition thereof.

[0018] In one embodiment, the viscosity of the polyamide sheet or polyamide resin is tested at a temperature between the melting point of the sheet or resin and 100°C above the melting point, and may further be 200–340°C, for example 220°C, 240°C, 250°C, 280°C, 290°C, 300°C, 310°C, 320°C, or 330°C.

[0019] In one embodiment, the viscosity of the polyamide sheet or polyamide resin can be directly obtained using a rotational rheometer. Further, a rotational rheometer of the Anton Paar MCR302 is used to measure the melt viscosity of the polyamide sheet, with a shear rate set to 1 s. -1 The frequency was 1 Hz, the heating rate was 3℃ / s, and the test temperature was from the melting point of the polyamide sheet or polyamide resin to 20-100℃ above the melting point, and further to 30-90℃ above the melting point.

[0020] In one embodiment, the polyamide sheet or polyamide resin is subjected to a shear rate of 1 second at a temperature of 200–340°C. -1 The viscosity under these conditions is 350–900 Pa·s, for example 400 Pa·s, 410 Pa·s, 415 Pa·s, 420 Pa·s, 450 Pa·s, 500 Pa·s, 510 Pa·s, 515 Pa·s, 520 Pa·s, 550 Pa·s, 600 Pa·s, 650 Pa·s, 690 Pa·s, 695 Pa·s, 700 Pa·s, 750 Pa·s, 800 Pa·s, 850 Pa·s, 880 Pa·s, 885 Pa·s, and 890 Pa·s.

[0021] In one embodiment, the melting point of the polyamide sheet or polyamide resin can be 150–320°C, more specifically 180–320°C, and even more specifically 200–320°C, for example 190°C, 195°C, 197°C, 200°C, 250°C, 260°C, 265°C, 266°C, 270°C, 290°C, 295°C, 298°C, 300°C, or 310°C.

[0022] In one embodiment, the polyamide sheet or polyamide resin has a melting point of 150–240°C, and its melting point is 230–280°C with a shear rate of 1 second. -1 The viscosity under these conditions is 350–700 Pa·s, and further 505–525 Pa·s.

[0023] In one embodiment, the polyamide sheet or polyamide resin has a melting point of 190–200°C, and its shear rate is 1 second at 278–280°C. -1 The viscosity under these conditions is 350–700 Pa·s, and further 505–525 Pa·s.

[0024] In one embodiment, the polyamide sheet or polyamide resin has a melting point of 240–270°C, and its shear rate is 1 second at 280–330°C. -1 The viscosity under the given conditions is 400–700 Pa·s, and further 400–450 Pa·s.

[0025] In one embodiment, the polyamide sheet or polyamide resin has a melting point of 260–270°C, and its shear rate is 1 second at 328–330°C. -1 The viscosity under the given conditions is 400–700 Pa·s, and further 400–450 Pa·s.

[0026] In one embodiment, the polyamide sheet or polyamide resin has a melting point of 270–320°C, and its melting point is 300–340°C with a shear rate of 1 second. -1 The viscosity under these conditions is 700–900 Pa·s, and further 870–895 Pa·s.

[0027] In one embodiment, the polyamide sheet or polyamide resin has a melting point of 295–300°C, and its melting point is 338–340°C with a shear rate of 1 second. -1 The viscosity under these conditions is 700–900 Pa·s, and further 870–895 Pa·s.

[0028] In one embodiment, the viscosity of the polyamide sheet can be adjusted by modifying the polyamide sheet manufacturing process and the viscosity of the polyamide resin used as the raw material. Furthermore, the viscosity of the polyamide resin can be controlled by solid-phase thickening, adjusting resin synthesis parameters, etc.

[0029] In one embodiment, the thickness of the polyamide sheet is 0.05–1 mm, more preferably 0.05–0.3 mm, and even more preferably 0.05–0.1 mm, for example 0.06 mm, 0.08 mm, 0.1 mm, 0.12 mm, 0.15 mm, 0.2 mm, 0.25 mm, 0.5 mm, or 0.8 mm. Sheets with a thickness of 0.5 mm or less may also be referred to as "films".

[0030] In one embodiment, the density of the polyamide sheet is 1.0–1.2 g / cm³. 3 For example, 1.05 g / cm³ 3 1.1g / cm 3 1.14 g / cm 3 1.15g / cm 3 1.17g / cm 3 .

[0031] In one embodiment, the moisture content of the polyamide sheet is below 500 ppm, and may further be 50 to 500 ppm, such as 100 ppm, 150 ppm, 200 ppm, 250 ppm, 300 ppm, 350 ppm, 400 ppm, or 450 ppm.

[0032] In one embodiment, the method for preparing polyamide sheets includes: heating and melting polyamide resin or a composition thereof; casting the resulting polyamide melt (e.g., through a T-die) onto a cooling roller, and then drawing and winding it to obtain a polyamide cast sheet. Further, the surface temperature of the cooling roller can be, for example, 50°C.

[0033] In one embodiment, when the thickness of the polyamide sheet is 0.05 to 0.3 mm, it can be prepared by coating, blown film blowing or calendering.

[0034] In one embodiment, the polyamide sheet is made from a polyamide resin or a composition thereof, wherein the monomers for preparing the polyamide resin include a diamine and a diacid, the diamine including pentanediamine; and the diacid including one or more of an aliphatic diacid having 4 to 18 carbon atoms and an aromatic diacid having 8 to 10 carbon atoms (e.g., 9).

[0035] In one embodiment, the molar ratio of the diamine and the diacid used to prepare the polyamide resin can be (1 to 1.05):1, for example, 1.01:1, 1.02:1, 1.03:1, or 1.04:1.

[0036] In one embodiment, the diamine includes pentanediamine and other diamines, wherein the other diamines may be one or more aliphatic diamines (excluding pentanediamine) having 4 to 16 carbon atoms; further, the other diamines may be one or more of butanediamine, hexanediamine, heptadecanediamine, octanediamine, nonanediamine, decanedanediamine, undecanediamine, dodecanediamine, tridecanediamine, tetradecanediamine, pentadecanediamine, and hexadecanediamine.

[0037] In one embodiment, the aliphatic dicarboxylic acid having 4 to 18 carbon atoms can be one or more of the following: succinic acid, glutaric acid, adipic acid, pimelic acid, octanoic acid, azelaic acid, sebacic acid, undecanoic acid, dodecanoic acid, tridecanoic acid, tetradecanoic acid, pentadecanoic acid, hexadecanoic acid, heptadecanoic acid, and octadecanoic acid.

[0038] In one embodiment, the aromatic dicarboxylic acid may be one, two, or three of terephthalic acid, isophthalic acid, and phthalic acid.

[0039] In one embodiment, the polyamide resin is obtained by copolymerization of pentanediamine and a long-chain dicarboxylic acid, and its melting point is 190-220°C; the long-chain dicarboxylic acid is selected from one or more of sebacic acid, undecanoic acid, dodecanoic acid, tridecanoic acid, tetradecanoic acid, pentadecanoic acid, hexadecanoic acid, heptadecanoic acid, and octadecanoic acid.

[0040] In one embodiment, the polyamide resin is obtained by copolymerization of pentanediamine, long-chain dicarboxylic acid and terephthalic acid, and has a melting point of 190-320°C; the long-chain dicarboxylic acid is selected from one or more of sebacic acid, undecanoic acid, dodecanoic acid, tridecanoic acid, tetradecanoic acid, pentadecanoic acid, hexadecanoic acid, heptadecanoic acid and octadecanoic acid.

[0041] In one embodiment, the polyamide resin is obtained by copolymerization of pentanediamine, adipic acid and terephthalic acid, and has a melting point of 240–320°C.

[0042] In one embodiment, the polyamide resin is obtained by copolymerization of pentanediamine, hexamethylenediamine, adipic acid and terephthalic acid, and has a melting point of 230–320°C.

[0043] In one embodiment, the polyamide resin includes a diamine structural unit and a diacid structural unit. The diamine structural unit includes -NH(CH2)5NH-, and the diacid structural unit is derived from a diacid, which includes one or more aliphatic diacids having 4 to 18 carbon atoms and aromatic diacids having 8 to 10 carbon atoms.

[0044] In one embodiment, the diamine structural unit includes -NH(CH2)5NH- and -NH(CH2). m NH-, m is selected from 4 to 16 and m is not equal to 5. For example, m can be 4, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15 or 16.

[0045] In one embodiment, the dicarboxylic acid structural unit includes -CO(CH2). n CO-, n is selected from 2 to 16, and n can be 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15 or 16.

[0046] In one embodiment, the pentanediamine is bio-based pentanediamine, which refers to pentanediamine synthesized from compounds derived from biomass, such as glucose and lysine, through enzyme reactions, yeast reactions, or fermentation reactions during the monomer synthesis process.

[0047] In one embodiment, the polyamide resin is a bio-based polyamide resin, such as selected from bio-based polyamide PA56, bio-based polyamide PA510, bio-based polyamide PA511, bio-based polyamide PA512, bio-based polyamide PA513, bio-based polyamide PA514, bio-based polyamide PA515, and bio-based polyamide PA516, bio-based polyamide PA56 / 5T, bio-based polyamide PA510 / 5T, bio-based polyamide PA511 / 5T, bio-based polyamide PA512 / 5T, bio-based polyamide PA513 / 5T, bio-based polyamide PA514 / 5T, bio-based polyamide PA515 / 5T, bio-based polyamide PA516 / 5T, bio-based polyamide PA56 / 5I, and commercially available polyamides.

[0048]

[0049]

[0050]

[0051] Any one or more of the following.

[0052] In one embodiment, the polyamide resin composition for preparing polyamide sheets includes a polyamide resin and functional additives, said functional additives including one or more of antioxidants, heat stabilizers, lubricants, flame retardants, inorganic fillers, flow modifiers, and antistatic agents, such as commercially available antioxidant 168 and flow modifiers of aliphatic dicarboxylic acids having 12 to 16 carbon atoms.

[0053] In one embodiment, the amount of the functional additive added is 0.001 to 15 wt% of the total mass of the polyamide resin composition.

[0054] In one embodiment, the polyamide sheet may be the polyamide 56 resin film disclosed in patent application CN111763313A, the raw material of which is bio-based polyamide resin obtained by copolymerization of bio-based pentanediamine and adipic acid.

[0055] In one embodiment, a bio-based polyamide resin, such as The fact that some of the raw materials for the product series are derived from renewable plant resources further enhances its commercial potential and scientific research value as a matrix resin for composite materials.

[0056] In one embodiment, the thickness of the fiber fabric used to prepare the fiber-reinforced composite material can be 0.05 to 0.5 mm, for example, 0.09 mm, 0.2 mm, or 0.3 mm.

[0057] In one embodiment, the thickness of the fiber fabric used to prepare the fiber-reinforced composite material can be 0.08 to 0.4 mm, more specifically 0.3 to 0.4 mm, for example 0.1 mm, 0.2 mm, or 0.35 mm.

[0058] In one embodiment, the thickness of the fiber fabric used to prepare the fiber-reinforced composite material can be 0.05 to 0.1 mm, for example, 0.06 mm, 0.07 mm, 0.08 mm, or 0.09 mm.

[0059] In one embodiment, the basis weight of the fiber fabric can be 650 g / m². 2 The following values ​​can be further increased to 50–650 g / m³. 2 For example, 70g / m 2 104g / m 2 200g / m 2 300g / m 2 400g / m 2 500g / m 2 550g / m 2 580g / m 2 600g / m 2 620g / m 2 .

[0060] In one embodiment, the fiber fabric (i.e., continuous fiber fabric) includes continuous fibers, which include one or more of glass fibers, carbon fibers, basalt fibers, aramid fibers, polyolefin fibers, and natural fibers.

[0061] In one embodiment, the fibrous fabric includes continuous fibrous cloth and / or continuous fibrous yarn.

[0062] In one embodiment, the fiber fabric includes one or more of checkered fabric, non-crimped fabric, and three-dimensional fabric. Further, the checkered fabric may be selected from one or more of plain weave, twill weave, and satin weave; the non-crimped fabric may be selected from one or more of uniaxial, biaxial, triaxial, and quadriaxial structures; and the three-dimensional fabric may be selected from three-dimensional orthogonal structures and / or three-dimensional interlocking structures.

[0063] In one embodiment, the orientation of continuous fibers in the fibrous fabric is crossed at 0 to 90°, preferably 90° and / or 45°.

[0064] In one embodiment, the fiber fabric is a biaxial glass fiber fabric, wherein the continuous fiber orientation is 0° / 90° or +45° / -45°.

[0065] In one embodiment, the fiber fabric is a plain weave glass fiber cloth, wherein the continuous fiber orientation is 0° / 90° or +45° / -45°.

[0066] In one embodiment, the fiber fabric is a twill-weave glass fiber cloth, wherein the continuous fiber orientation is 0° / 90° or +45° / -45°.

[0067] In one embodiment, based on the total weight of the polyamide sheet and fiber fabric used to prepare the fiber-reinforced composite material, the mass content of the fiber fabric can be 50% to 85%, for example, 55%, 60%, 65%, 70%, 75%, or 80%.

[0068] In one embodiment, the mass content of the fiber fabric can be 70-80%, for example, 70%, 77%, 78%, or 79%, based on the total weight of the polyamide sheet and fiber fabric used to prepare the fiber-reinforced composite material.

[0069] In one embodiment, based on the total weight of the polyamide sheet and fiber fabric used to prepare the fiber-reinforced composite material, the mass content of the fiber fabric can be 55-70%, more specifically 58-62%, for example 59%, 60%, or 61%.

[0070] In one embodiment, based on the total volume of the polyamide sheet and fiber fabric used to prepare the fiber-reinforced composite material, the volume content of the fiber fabric can be 30% to 72%, for example, 35%, 40%, 45%, 50%, 55%, 60%, 65%, or 70%; or, based on the total volume of the fiber-reinforced composite material, the volume of the fiber fabric is 30% to 72% of the total volume of the composite material, for example, 35%, 40%, 45%, 50%, 55%, 60%, 65%, or 70%.

[0071] In one embodiment, based on the total volume of the polyamide sheet and fiber fabric used to prepare the fiber-reinforced composite material (or based on the total volume of the fiber-reinforced composite material), the volume content of the fiber fabric can be 55% to 65%, more preferably 58% to 62%, for example 56%, 57%, 58%, 59%, 60%, 61%, 62%, 63%, or 64%.

[0072] In one embodiment, the volume content of the fiber fabric can be 35% to 45%, more preferably 38% to 42%, for example 36%, 37%, 38%, 39%, 40%, 41%, 42%, 43%, or 44%, based on the total volume of the polyamide sheet and fiber fabric used to prepare the fiber-reinforced composite material (or based on the total volume of the fiber-reinforced composite material).

[0073] In one embodiment, the porosity of the fiber-reinforced composite material can be 0.1% to 0.5%, for example, 0.28%, 0.29%, 0.3%, 0.32%, 0.33%, 0.35%, 0.36%, 0.37%, or 0.38%.

[0074] In one embodiment, the porosity of the fiber-reinforced composite material can be 0.2–0.38%, and more preferably 0.25–0.38%.

[0075] In one embodiment, the fiber-reinforced composite material exists in the form of a fiber-reinforced composite board, the thickness of which can be an ultra-thin polyamide composite board of 0.3 to 0.6 mm, such as 0.3 mm, 0.4 mm, or 0.5 mm.

[0076] In one embodiment, the fiber-reinforced composite material exists in the form of a fiber-reinforced composite board, the thickness of which can be a polyamide composite board of 1 to 20 mm, such as 2 mm, 4 mm, 8 mm, or 20 mm.

[0077] In one embodiment, the fiber-reinforced composite material (or fiber-reinforced composite board) has a thickness of 4 mm and a fiber fabric mass content of 70-80% (or a fiber fabric volume content of 55-65%), and its flexural strength can be 620-720 MPa, for example 624 MPa, 625 MPa, 630 MPa, 650 MPa, 660 MPa, 669 MPa, 670 MPa, 674 MPa, 675 MPa, 678 MPa, 679 MPa, 680 MPa, 700 MPa, 710 MPa, 716 MPa, and 717 MPa.

[0078] In one embodiment, the fiber-reinforced composite material (or fiber-reinforced composite board) has a thickness of 4 mm and a fiber fabric mass content of 70-80% (or a fiber fabric volume content of 55-65%), and its interlaminar shear strength can be 50-80 MPa, for example 52 MPa, 53 MPa, 54 MPa, 60 MPa, 65 MPa, 68 MPa, 69 MPa, 70 MPa, 71 MPa, 74 MPa, or 75 MPa.

[0079] In one embodiment, the fiber-reinforced composite material (or fiber-reinforced composite board) has a thickness of 0.4 mm and a fiber fabric mass content of 55-65% (or a fiber fabric volume content of 35-45%), and its tensile strength can be 300-500 MPa, such as 305 MPa, 320 MPa, 340 MPa, 380 MPa, 400 MPa, 420 MPa, 480 MPa, and 495 MPa.

[0080] In one embodiment, a multilayer structure comprising polyamide sheets and fiber fabrics is laminated to obtain a fiber-reinforced composite material (or a fiber-reinforced composite laminate); wherein the multilayer structure comprises one or more layers (e.g., two layers) of polyamide sheets and one or more layers of fiber fabrics stacked together, that is, the multilayer structure is formed by laying up (e.g., alternatingly laying) one or more layers of polyamide sheets and one or more layers of fiber fabrics. For example, the multilayer structure used for lamination may include two layers of polyamide sheets and two layers of fiber fabrics, arranged from top to bottom as: polyamide sheet, fiber fabric, polyamide sheet, fiber fabric, or in the following order: polyamide sheet, fiber fabric, fiber fabric, polyamide sheet.

[0081] In one embodiment, one or more layers of polyamide sheets and one or more layers of fiber fabrics are alternately arranged in the multilayer structure, that is, the polyamide sheets and the fiber fabrics are adjacent to or connected to each other.

[0082] In one embodiment, the multilayer structure for lamination includes a first surface layer, at least one intermediate layer, and a second surface layer arranged sequentially, wherein the first and second surface layers are both polyamide sheets, and the at least one intermediate layer comprises a fibrous fabric. For example, the multilayer structure may include three layers, in the following order: a first surface layer (polyamide sheet), an intermediate layer (fibrous fabric), and a second surface layer (polyamide sheet). Alternatively, the multilayer structure may include five layers, in the following order: a first surface layer (polyamide sheet), a first intermediate layer (fibrous fabric), a second intermediate layer (polyamide sheet), a third intermediate layer (fibrous fabric), and a second surface layer (polyamide sheet).

[0083] In one embodiment, at least one intermediate layer of the multilayer structure comprises one or more layers of fibrous fabric and at least one or more layers of polyamide sheet.

[0084] One embodiment of the present invention provides a method for preparing the above-mentioned fiber-reinforced composite material, comprising hot pressing (molding) a multilayer structure to obtain a fiber-reinforced composite material; wherein the multilayer structure comprises one or more polyamide sheets and one or more fiber fabrics.

[0085] In one embodiment, the molding process includes: preheating the laminated structure at 0-1 MPa (e.g., 0.1 MPa, 0.2 MPa, 0.5 MPa, 0.6 MPa, 0.8 MPa) for 5-10 minutes, followed by degassing, and maintaining the pressure at 5-8 MPa for 6-9 minutes. The temperature during the molding process (i.e., the temperature of the molding machine) is maintained at 20-100°C (e.g., 30°C, 40°C, 50°C, 60°C, 70°C, 80°C, 90°C) above the melting point of the polyamide sheet.

[0086] In one embodiment, the polyamide sheet is dried to a moisture content of less than 1000 ppm, for example, 100 to 500 ppm, before compression molding.

[0087] In one embodiment, the polyamide sheet has a melting point of 150–240°C, and the molding temperature is controlled at 230–280°C. It is preheated at 0–1 MPa for 5–10 min, vented, and held at 8 MPa pressure for 6–9 min.

[0088] In one embodiment, the polyamide sheet has a melting point of 190-200°C, and the molding temperature is controlled at 278-280°C. It is preheated at 0-1MPa for 5-10 minutes, vented, and held at 8MPa pressure for 6-9 minutes.

[0089] In one embodiment, the polyamide sheet has a melting point of 240–270°C, and the temperature is controlled at 280–330°C during compression molding. It is preheated for 5–10 minutes under 0–1 MPa conditions, vented, and held at 8 MPa pressure for 6–9 minutes.

[0090] In one embodiment, the polyamide sheet has a melting point of 260-270°C, and the molding temperature is controlled at 328-330°C. It is preheated at 0-1MPa for 5-10 minutes, vented, and held at 8MPa pressure for 6-9 minutes.

[0091] In one embodiment, the polyamide sheet has a melting point of 270–320°C, and the temperature is controlled at 300–340°C during compression molding. It is preheated for 5–10 minutes under 0–1 MPa conditions, vented, and held at 8 MPa pressure for 6–9 minutes.

[0092] In one embodiment, the polyamide sheet has a melting point of 295–300°C, and the molding temperature is controlled at 338–340°C. The sheet is preheated at 0–1 MPa for 5–10 minutes, vented, and held at 8 MPa pressure for 6–9 minutes.

[0093] In one embodiment, the apparatus used for compression molding can be a double steel strip compression molding machine or a flat vulcanizing machine.

[0094] One embodiment of the present invention provides the application of the above-mentioned polyamide sheet in the preparation of fiber-reinforced composite materials, wherein the fiber-reinforced composite materials are obtained by a lamination molding process.

[0095] In one embodiment of the present invention, the fiber-reinforced composite material exists in the form of a fiber-reinforced composite panel.

[0096] The fiber-reinforced composite material (or fiber-reinforced composite board) of one embodiment of the present invention can be used in new energy vehicles, wind power generation, building formwork, aerospace and other fields.

[0097] One embodiment of the present invention provides a polyamide board (or fiber-reinforced composite board) comprising the above-described fiber-reinforced composite material.

[0098] One embodiment of the present invention provides a product comprising the polyamide sheet described above. Further, the product may be a molded article.

[0099] One embodiment of the fiber-reinforced composite material of the present invention is obtained by hot pressing (e.g., molding) polyamide sheets and fiber fabrics. During the molding process, the resin sheet impregnates the fiber fabric layer. The use of polyamide sheets with a specific viscosity can significantly improve the molding and impregnation effect, resulting in a laminate composite material with excellent mechanical properties. This not only benefits sustainable development planning but also meets the design requirements for energy conservation, emission reduction, and lightweighting in various fields. Specifically, ultra-thin polyamide composite sheets with a thickness of 0.3–0.6 mm are mainly used in 3C (computer, communication, and consumer electronics), copper-clad laminates, and aerospace fields, while polyamide composite sheets with a thickness of 1–20 mm are mainly used in transportation and logistics, new energy, construction, and aerospace fields.

[0100] The present invention discloses a method for preparing fiber-reinforced composite materials, which is simple to operate and can obtain composite materials with good impregnation effect and excellent mechanical properties.

[0101] The preparation of a fiber-reinforced composite material according to one embodiment of the present invention will be further described below with reference to the accompanying drawings and specific embodiments. In each embodiment and comparative example, the molding machine used for compression molding is a flat vulcanizing machine, and all raw materials are dried to a moisture content of less than 500 ppm before use. The raw materials and testing methods involved in each embodiment are as follows.

[0102] raw material

[0103] The viscosity of the polyamide resin used as the raw material for polyamide sheets was adjusted by solid-phase thickening. The solid-phase thickening temperature was 120–200℃, and the time was 4–24 h.

[0104] Plain weave fiberglass cloth (hereinafter referred to as plain weave fiberglass cloth): thickness 0.35mm, face weight 600g / m² 2 The continuous fiber orientation is 0° / 90°; the raw material glass fiber is China Jushi E6DR17-1200-352B; the plain weave glass fiber cloth is EWR600T plain weave, purchased from Taian Juli Co., Ltd.

[0105] Ultra-thin plain weave fiberglass cloth (hereinafter referred to as plain weave electronic cloth): thickness 0.07mm, basis weight 104g / m² 2 The continuous fiber orientation is 0° / 90°; the raw material glass fiber is Chongqing International EC E225 1 / 0; the plain weave electronic cloth grade is L2116-50FE plain weave, purchased from Chongqing Tianhuan Materials Technology Co., Ltd.

[0106] Twill fiberglass cloth (hereinafter referred to as twill fiberglass cloth): thickness 0.35mm, face weight 600g / m² 2 The continuous fiber orientation is 0° / 90°. The raw material glass fiber is China Jushi E6DR17-1200-352B; the twill glass fiber cloth is EWR600T twill and was purchased from Taian Juli Co., Ltd.

[0107] Test methods

[0108] 1. Viscosity

[0109] The viscosity of the polyamide sheet was measured using an Anton Paar MCR302 rheometer, with a shear rate of 1 s⁻¹. -1 The frequency is 1Hz and the heating rate is 3℃ / s.

[0110] 2. Mechanical properties

[0111] The flexural strength of the composite material (or composite laminate) was measured according to ASTM D7264, the interlaminar shear strength according to ASTM D2344, the tensile strength according to ASTM D3039, and the tensile modulus according to ASTM D3039.

[0112] 3. Fiber content test

[0113] The fiber content of the composite material (or composite laminate) was measured according to the national standard GB / T 9345.1-2008, after calcination at 700℃ for two hours.

[0114] Preparation Example 1

[0115] Bio-based polyamide resin A1 (melting point 197℃) is heated and melted, and the resulting melt is cast through a T-die onto a cooling roller with a surface temperature of 50℃. Then, it is drawn and wound to obtain polyamide sheet A1. The bio-based polyamide resin A1 is obtained by copolymerizing bio-based 1,5-pentanediamine and tridecanoic acid, with an amino acid molar ratio of 1.05:1.

[0116] The obtained polyamide sheet A1 has a thickness of 0.1 mm and a density of 1.17 g / cm³. 3 Its melting point is 197℃, and it is at 280℃ with a shear rate of 1s. -1The viscosity at that time was 515 Pa·s.

[0117] Preparation Example 2

[0118] Polyamide sheet B1 (melting point 266°C) was prepared using the same process as in Preparation Example 1, except that the raw material used was bio-based polyamide resin B1. Bio-based polyamide resin B1 was obtained by copolymerizing bio-based 1,5-pentanediamine, 1,6-hexanediamine, adipic acid, and terephthalic acid in a molar ratio of 5.05:5:4:6.

[0119] The resulting polyamide sheet B1 has a thickness of 0.1 mm and a density of 1.17 g / m³. 3 Its melting point is 266℃, and it withstands temperatures of 330℃ and shear rates of 1 second. -1 The viscosity at that time was 413 Pa·s.

[0120] Preparation Example 3

[0121] Polyamide sheet C1 (melting point 298°C) was prepared using the same process as in Preparation Example 1, except that the raw material used was bio-based polyamide resin C1. Bio-based polyamide resin C1 was obtained by copolymerizing bio-based 1,5-pentanediamine, dodecanoic acid, and terephthalic acid in a molar ratio of 1:0.34:0.66.

[0122] The obtained polyamide sheet C1 has a thickness of 0.1 mm and a density of 1.14 g / cm³. 3 Its melting point is 298℃, and it withstands temperatures of 340℃ and shear rates of 1 second. -1 The viscosity at that time was 881 Pa·s.

[0123] Preparation Example 4

[0124] Polyamide sheet A4 (melting point 197°C) was prepared using the same raw materials (bio-based polyamide resin A1) and process as in Preparation Example 1, the only difference being that the thickness of the polyamide sheet A4 was 0.06 mm.

[0125] The obtained polyamide sheet A4 has a thickness of 0.06 mm and a density of 1.17 g / cm³. 3 Its melting point is 197℃, and it is at 280℃ with a shear rate of 1s. -1 The viscosity at that time was 515 Pa·s.

[0126] Preparation Example 5

[0127] Polyamide sheet B3 (melting point 266°C) was prepared using the same raw materials (bio-based polyamide resin B1) and process as in Preparation Example 2, the only difference being that the thickness of the polyamide sheet B3 was 0.06 mm.

[0128] The resulting polyamide sheet B3 has a thickness of 0.06 mm and a density of 1.17 g / m³. 3 Its melting point is 266℃, and it withstands temperatures of 330℃ and shear rates of 1 second. -1 The viscosity at that time was 413 Pa·s.

[0129] Preparation Example 6

[0130] Polyamide sheet C3 (melting point 298°C) was prepared using the same raw materials (bio-based polyamide resin C1) and process as in Preparation Example 3, the only difference being that the thickness of the polyamide sheet C3 was 0.06 mm.

[0131] The obtained polyamide sheet C3 has a thickness of 0.06 mm and a density of 1.14 g / cm³. 3 Its melting point is 298℃, and it withstands temperatures of 340℃ and shear rates of 1 second. -1 The viscosity at that time was 881 Pa·s.

[0132] Preparation Example 7

[0133] Polyamide sheet A3 (melting point 197°C) was prepared using the same process as in Preparation Example 1, except that the raw material used was bio-based polyamide resin A1 that had undergone solid-phase thickening.

[0134] The resulting polyamide sheet A3 has a thickness of 0.1 mm and a density of 1.17 g / cm³. 3 Its melting point is 197℃, and it is at 280℃ with a shear rate of 1s. -1 The viscosity at that time was 697 Pa·s.

[0135] Preparation Example 8

[0136] Polyamide sheet B4 (melting point 266°C) was prepared using the same raw material (bio-based polyamide resin B3) and process as in Preparation Example 5, the only difference being that the raw material used was bio-based polyamide resin B3 that had undergone solid-phase thickening.

[0137] The obtained polyamide sheet B4 has a thickness of 0.06 mm and a density of 1.17 g / m³. 3 Its melting point is 266℃, and it withstands temperatures of 330℃ and shear rates of 1 second. -1 The viscosity at that time was 450 Pa·s.

[0138] Preparation Example 9

[0139] Polyamide sheet B5 (melting point 266°C) was prepared using the same raw material (bio-based polyamide resin B3) and process as in Preparation Example 5, the only difference being that the raw material used was bio-based polyamide resin B3 that had undergone solid-phase thickening.

[0140] The resulting polyamide sheet B5 has a thickness of 0.06 mm and a density of 1.17 g / m³. 3 Its melting point is 266℃, and it withstands temperatures of 330℃ and shear rates of 1 second. -1 The viscosity at that time was 500 Pa·s.

[0141] Preparation Example 10

[0142] Polyamide sheet B6 (melting point 266°C) was prepared using the same raw material (bio-based polyamide resin B3) and process as in Preparation Example 5, the only difference being that the raw material used was bio-based polyamide resin B3 that had undergone solid-phase thickening.

[0143] The obtained polyamide sheet B6 has a thickness of 0.06 mm and a density of 1.17 g / m³. 3 Its melting point is 266℃, and it withstands temperatures of 330℃ and shear rates of 1 second. -1 The viscosity at that time was 600 Pa·s.

[0144] Comparative Preparation Example 1

[0145] Polyamide sheet A2 (melting point 197°C) was prepared using the same process as in Preparation Example 1, except that the raw material used was bio-based polyamide resin A1 that had undergone solid-phase thickening.

[0146] The resulting polyamide sheet A2 has a thickness of 0.1 mm and a density of 1.17 g / cm³. 3 Its melting point is 197℃, and it is at 280℃ with a shear rate of 1s. -1 The viscosity at that time was 1351 Pa·s.

[0147] Comparative Preparation Example 2

[0148] Polyamide sheet B2 (melting point 266°C) was prepared using the same process as in Preparation Example 1, the only difference being that the raw material used was bio-based polyamide resin B1 that had undergone solid-phase thickening.

[0149] The resulting polyamide sheet B2 has a thickness of 0.1 mm and a density of 1.17 g / m³. 3 Its melting point is 266℃, and it withstands temperatures of 330℃ and shear rates of 1 second. -1 The viscosity at that time was 1944 Pa·s.

[0150] Comparative preparation example 3

[0151] Polyamide sheet C2 (melting point 298°C) was prepared using the same process as in Preparation Example 1, the only difference being that the raw material used was bio-based polyamide resin C1 that had undergone solid-phase thickening.

[0152] The obtained polyamide sheet C2 has a thickness of 0.1 mm and a density of 1.14 g / cm³. 3 Its melting point is 298℃, and it withstands temperatures of 340℃ and shear rates of 1 second. -1 The viscosity at that time was 1083 Pa·s.

[0153] Comparative preparation example 4

[0154] Polyamide sheet B7 (melting point 266°C) was prepared using the same raw material (bio-based polyamide resin B3) and process as in Preparation Example 5, the only difference being that the raw material used was bio-based polyamide resin B3 that had undergone solid-phase thickening.

[0155] The resulting polyamide sheet B7 has a thickness of 0.06 mm and a density of 1.17 g / m³. 3 Its melting point is 266℃, and it withstands temperatures of 330℃ and shear rates of 1 second. -1 The viscosity at that time was 900 Pa·s.

[0156] Comparative preparation example 5

[0157] Polyamide sheet B8 (melting point 266°C) was prepared using the same raw material (bio-based polyamide resin B3) and process as in Preparation Example 5, the only difference being that the raw material used was bio-based polyamide resin B3 that had undergone solid-phase thickening.

[0158] The obtained polyamide sheet B8 has a thickness of 0.06 mm and a density of 1.17 g / m³. 3 Its melting point is 266℃, and it withstands temperatures of 330℃ and shear rates of 1 second. -1 The viscosity at that time was 1200 Pa·s.

[0159] Comparative preparation example 6

[0160] Polyamide sheet B9 (melting point 266°C) was prepared using the same raw material (bio-based polyamide resin B3) and process as in Preparation Example 5, the only difference being that the raw material used was bio-based polyamide resin B3 that had undergone solid-phase thickening.

[0161] The resulting polyamide sheet B9 has a thickness of 0.06 mm and a density of 1.17 g / m³. 3 Its melting point is 266℃, and it withstands temperatures of 330℃ and shear rates of 1 second. -1 The viscosity at that time was 1500 Pa·s.

[0162] Example 1

[0163] S1: Cut multiple polyamide sheets A1 and multiple twill fiberglass cloths to the size of the mold. Place a release cloth on the upper and lower layers of the mold, and then place polyamide sheets A1 and twill fiberglass cloths in the middle. Polyamide sheets A1 are used as the first surface layer 100, twill fiberglass cloth is laid on the first surface layer 100 as the first intermediate layer 101, and polyamide sheets A1 are laid on the first intermediate layer 101 as the second intermediate layer 102. The twill fiberglass cloth and polyamide sheets A1 are laid alternately in the same manner, with the last polyamide sheet A1 laid as the second surface layer 200, resulting in a multi-layer structure comprising 19 layers (see [link]). Figure 1 The polyamide sheet A1 consists of 9 layers, the twill fiberglass cloth consists of 10 layers, and the two polyamide sheets A1 are located at both ends, serving as the first surface layer 100 and the second surface layer 200.

[0164] S2: The multi-layer structure from step S1 is molded on a flat vulcanizing machine. The temperature of the molding machine is controlled at 280℃. The machine is preheated at 1MPa for 8 minutes, the air is vented, and the pressure is maintained at 8MPa for 6 minutes to prepare a fiber-reinforced polyamide composite laminate with a thickness of 4mm and 10 layers of fiber fabric.

[0165] Example 2

[0166] S1: Prepare a multilayer structure using the same method as step S1 in Example 1: the only difference being that polyamide sheet B1 is used instead of polyamide sheet A1.

[0167] S2: The multi-layer structure from step S1 is molded on a flat vulcanizing machine. The temperature of the molding machine is controlled at 330℃. The machine is preheated at 1MPa for 8 minutes, the air is vented, and the pressure is maintained at 8MPa for 8 minutes to prepare a fiber-reinforced polyamide composite laminate with a thickness of 4mm and 10 layers of fiber fabric.

[0168] Example 3

[0169] S1: Prepare a multilayer structure using the same method as step S1 in Example 1: the only difference being that polyamide sheet C1 is used instead of polyamide sheet A1.

[0170] S2: The multi-layer structure from step S1 is molded on a flat vulcanizing machine. The temperature of the molding machine is controlled at 340℃. The machine is preheated at 1MPa for 10 minutes, the air is vented, and the pressure is maintained at 8MPa for 9 minutes to prepare a fiber-reinforced polyamide composite laminate with a thickness of 4mm and 10 layers of fiber fabric.

[0171] Example 4

[0172] The fiber-reinforced polyamide composite laminate was prepared using the same method as in Example 1, except that plain fiberglass cloth was used instead of twill fiberglass cloth.

[0173] Example 5

[0174] The fiber-reinforced polyamide composite laminate was prepared using the same method as in Example 1, except that polyamide sheet A3 was used instead of polyamide sheet A1.

[0175] Example 6

[0176] S1: The multilayer structure is prepared using the same method as step S1 in Example 1, except that: polyamide sheet A4 is used instead of polyamide sheet A1; plain weave electronic cloth is used instead of twill fiberglass cloth; a multilayer structure including 9 layers is obtained; wherein, there are 5 layers of polyamide sheet A4 and 4 layers of plain weave electronic cloth, and the two polyamide sheets A4 are located at both ends, serving as the first surface layer 100 and the second surface layer 200.

[0177] S2: The multi-layer structure from step S1 is molded on a flat vulcanizing machine. The temperature of the molding machine is controlled at 280℃. It is preheated at 1MPa for 8 minutes, the air is vented, and it is held at 8MPa pressure for 6 minutes to prepare a fiber-reinforced polyamide composite laminate with a thickness of 0.4mm and 4 layers of fiber fabric.

[0178] Example 7

[0179] S1: The multilayer structure is prepared using the same method as step S1 in Example 6, except that polyamide sheet B3 is used instead of polyamide sheet A4.

[0180] S2: The multi-layer structure from step S1 is molded on a flat vulcanizing machine. The temperature of the molding machine is controlled at 330℃. It is preheated at 1MPa for 8 minutes, the air is vented, and it is held at 8MPa pressure for 8 minutes to prepare a fiber-reinforced polyamide composite laminate with a thickness of 0.4mm and 4 layers of fiber fabric.

[0181] Example 8

[0182] S1: The multilayer structure was prepared using the same method as step S1 in Example 6, except that polyamide sheet C3 was used instead of polyamide sheet A4.

[0183] S2: The multi-layer structure from step S1 is molded on a flat vulcanizing machine. The temperature of the molding machine is controlled at 340℃. It is preheated at 1MPa for 10 minutes, the air is vented, and it is held at 8MPa for 9 minutes to obtain a fiber-reinforced polyamide composite laminate with a thickness of 0.4mm and 4 layers of fiber fabric.

[0184] Example 9

[0185] S1: The multilayer structure is prepared using the same method as step S1 in Example 7, except that polyamide sheet B4 is used instead of polyamide sheet B3.

[0186] S2: The multi-layer structure from step S1 is molded on a flat vulcanizing machine. The temperature of the molding machine is controlled at 330℃. It is preheated at 1MPa for 10 minutes, the air is vented, and it is held at 8MPa for 8 minutes to obtain a fiber-reinforced polyamide composite laminate with a thickness of 0.4mm and 4 layers of fiber fabric.

[0187] Example 10

[0188] S1: The multilayer structure is prepared using the same method as step S1 in Example 7, except that polyamide sheet B5 is used instead of polyamide sheet B3.

[0189] S2: The multi-layer structure from step S1 is molded on a flat vulcanizing machine. The temperature of the molding machine is controlled at 330℃. It is preheated at 1MPa for 10 minutes, the air is vented, and it is held at 8MPa for 8 minutes to obtain a fiber-reinforced polyamide composite laminate with a thickness of 0.4mm and 4 layers of fiber fabric.

[0190] Example 11

[0191] S1: The multilayer structure is prepared using the same method as step S1 in Example 7, except that polyamide sheet B6 is used instead of polyamide sheet B3.

[0192] S2: The multi-layer structure from step S1 is molded on a flat vulcanizing machine. The temperature of the molding machine is controlled at 330℃. It is preheated at 1MPa for 10 minutes, the air is vented, and it is held at 8MPa for 8 minutes to obtain a fiber-reinforced polyamide composite laminate with a thickness of 0.4mm and 4 layers of fiber fabric.

[0193] Comparative Example 1

[0194] The fiber-reinforced polyamide composite laminate was prepared using the same method as in Example 1, except that polyamide sheet A2 was used instead of polyamide sheet A1.

[0195] Comparative Example 2

[0196] The fiber-reinforced polyamide composite laminate was prepared using the same method as in Example 2, except that polyamide sheet B2 was used instead of polyamide sheet B1.

[0197] Comparative Example 3

[0198] The fiber-reinforced polyamide composite laminate was prepared using the same method as in Example 3, except that polyamide sheet C2 was used instead of polyamide sheet C1.

[0199] Comparative Example 4

[0200] The fiber-reinforced polyamide composite laminate was prepared using the same method as in Example 7, except that polyamide sheet B7 was used instead of polyamide sheet B3.

[0201] Comparative Example 5

[0202] The fiber-reinforced polyamide composite laminate was prepared using the same method as in Example 7, except that polyamide sheet B8 was used instead of polyamide sheet B3.

[0203] Comparative Example 6

[0204] The fiber-reinforced polyamide composite laminate was prepared using the same method as in Example 7, except that polyamide sheet B9 was used instead of polyamide sheet B3.

[0205] According to the aforementioned method, the composite materials prepared in each embodiment and comparative example were subjected to relevant performance tests, and the results are shown in Table 1-2.

[0206] Table 1

[0207]

[0208]

[0209] Table 2

[0210]

[0211] As shown in Table 1, Examples 1 to 8 of this invention, by using polyamide sheets of specific viscosities as raw materials, can prepare composite materials with excellent mechanical properties. Moreover, the preparation method is simple to operate and has great potential for industrial scale-up applications, meeting the needs of energy conservation, emission reduction, and lightweight design in various fields. Examples 6 to 8, in particular, use ultra-thin plain-weave glass fiber cloth as reinforcing material to prepare thin composite materials with excellent mechanical properties, meeting the requirements of some 3C products and expanding the application of fiber-reinforced polyamide composite materials in mid-to-high-end fields.

[0212] The difference between Example 1 and Comparative Example 1 is that the viscosity of the polyamide sheet used is different. The polyamide sheet A1 in Example 1 was viscosed at 280°C and a shear rate of 1 s. -1The viscosity of the composite material in Example 1 was 515 Pa·s, while the corresponding viscosity of Comparative Example 1 was 1351 Pa·s. According to the results in Table 1, the mechanical properties of the composite material in Example 1, such as flexural strength and interlaminar shear strength, are significantly higher than those of the material in Comparative Example 1. The mechanical properties of materials determine the load-bearing capacity and stability of components and structures in fields such as automobiles and aerospace. Lower mechanical properties are detrimental to the safety, performance, and durability of materials in subsequent applications.

[0213] The performance comparison results of the composite materials of Example 2 and Comparative Example 2, and Example 3 and Comparative Example 3, are similar to those of Example 1 and Comparative Example 1. Therefore, by using polyamide sheets with a viscosity below 1000 Pa·s under specific conditions to prepare fiber-reinforced composite materials while maintaining the melting point of the polyamide sheet as constant, the mechanical properties of the material can be improved. Furthermore, the difference between Example 1 and Example 4 is that the fiber fabric used in Example 1 is twill fiberglass cloth, while that used in Example 4 is plain fiberglass cloth. According to the results in Table 1, the mechanical properties of the composite material of Example 1 are significantly better than those of Example 4.

[0214] Unlike other embodiments, the fiber fabric used in embodiments 6 to 8 is plain weave electronic cloth. According to the results in Table 1, the tensile strength can reach more than 350 MPa when the continuous fiber weight content is about 60%.

[0215] Unless otherwise specified, the terms used in this invention have the meanings commonly understood by those skilled in the art.

[0216] The embodiments described in this invention are for illustrative purposes only and are not intended to limit the scope of protection of this invention. Those skilled in the art can make various other substitutions, changes and improvements within the scope of this invention. Therefore, this invention is not limited to the above embodiments, but is only defined by the claims.

Claims

1. A fiber reinforced composite material comprising a resin matrix and one or more layers of a fiber fabric disposed in the resin matrix, the resin matrix comprising a polyamide resin; wherein, The polyamide resin has a viscosity of 1000 Pa-s or less at 200 to 340°C under a shear rate of 1 s -1 -1.

2. The composite material according to claim 1, which is produced by laminating a multi-layer structure comprising one or more polyamide sheets and one or more fiber fabrics disposed between the one or more polyamide sheets; and / or, The viscosity is obtained by a rotational rheometer.

3. The composite material of claim 2, wherein, The polyamide sheet or polyamide resin has a viscosity of 350 to 900 Pa-s under the conditions of 200 to 340°C and a shear rate of 1 s -1 -1. The melting point of the polyamide sheet or polyamide resin is 150-320°C; and / or, The thickness of the polyamide sheet is 0.05-1 mm; and / or, The thickness of the fiber fabric is 0.05-0.5 mm; and / or, The face weight of the fiber fabric is 650 g / m 2 The following.

4. The composite material of claim 2, wherein, The polyamide sheet or polyamide resin has a melting point of 150 to 240°C, and a viscosity of 350 to 700 Pa-s, further 505 to 525 Pa-s, at 230 to 280°C under a shear rate of 1 s -1 -1. The polyamide sheet or polyamide resin has a melting point of 240 to 270°C, a viscosity of 400 to 700 Pa-s, further 400 to 450 Pa-s, at 280 to 330°C under a shear rate of 1 s -1 -1, and a tensile strength of 50 to 100 MPa, further 60 to 90 MPa. The polyamide sheet or polyamide resin has a melting point of 270 to 320°C, a viscosity of 700 to 900 Pa-s, further 870 to 895 Pa-s, at 300 to 340°C, and a shear rate of 1 s -1 -1 under the conditions of a temperature of 300 to 340°C and a shear rate of 1 s"1. The thickness of the polyamide sheet is 0.05-0.3 mm; and / or, The thickness of the fiber fabric is 0.3-0.4 mm; and / or, The face weight of the fiber fabric is 50-650 g / m 2 .

5. The composite material of claim 2, wherein, The thickness of the polyamide sheet is 0.05-0.1 mm; and / or, The thickness of the fiber fabric is 0.05-0.1 mm; and / or, The mass content of the fiber fabric is 50-85% based on the total weight of the polyamide sheet and the fiber fabric; and / or, The volume of the fiber fabric is 30-72% of the total volume of the composite material.

6. The composite material of claim 2, wherein, The mass content of the fiber fabric is 70-80% based on the total weight of the polyamide sheet and the fiber fabric; and / or, The volume of the fiber fabric is 55-65% of the total volume of the composite material; and / or, The polyamide resin comprises a diamine structural unit and a diacid structural unit, the diamine structural unit comprises -NH(CH2)5NH-; the diacid structural unit is derived from a diacid, the diacid comprises one or more of aliphatic diacids with carbon atom number of 4-18 and aromatic diacids with carbon atom number of 8-10.

7. The composite material of claim 2, wherein, The fiber fabric comprises continuous fiber cloth and / or continuous fiber yarn; and / or, The fiber fabric comprises continuous fibers, the continuous fibers comprise one or more of glass fibers, carbon fibers, basalt fibers, aramid fibers, polyolefin fibers, natural fibers; and / or, The fiber fabric comprises one or more of check fabric, non-crimp fabric, three-dimensional fabric; and / or, The continuous fibers in the fiber fabric are crossed at 0-90°; and / or, The mass content of the fiber fabric is 55-65% based on the total weight of the polyamide sheet and the fiber fabric; and / or, The volume of the fiber fabric is 35-45% of the total volume of the composite material; and / or, The porosity of the fiber-reinforced composite material is 0.1-0.5%; and / or, The density of the polyamide sheet is 1.0 to 1.2 g / cm 3 ; and / or, The water content of the polyamide sheet is 500 ppm or less; and / or, The preparation monomers of the polyamide resin comprise diamines and diacids, the diamines comprise pentanediamine; the diacids comprise one or more of aliphatic diacids with carbon atom number of 4-18 and aromatic diacids with carbon atom number of 8-10.

8. The composite material of claim 7, wherein, The water content of the polyamide sheet is 50-500 ppm; and / or, the diamine includes pentanediamine and other diamines, the other diamines include one or more of aliphatic diamines with carbon atom number of 4-16, the aliphatic diamines with carbon atom number of 4-16 do not include pentanediamine; and / or, the aliphatic diacid with carbon atom number of 4-18 includes one or more of succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid, tridecanedioic acid, tetradecanedioic acid, pentadecanedioic acid, hexadecanedioic acid, heptadecanedioic acid and octadecanedioic acid; and / or, the aromatic diacid includes one, two or three of terephthalic acid, isophthalic acid and phthalic acid; or, the polyamide resin is obtained by copolymerization of pentanediamine and long carbon chain diacid, and has a melting point of 190-220℃; the long carbon chain diacid includes one or more of sebacic acid, undecanedioic acid, dodecanedioic acid, tridecanedioic acid, tetradecanedioic acid, pentadecanedioic acid, hexadecanedioic acid, heptadecanedioic acid and octadecanedioic acid; or, the polyamide resin is obtained by copolymerization of pentanediamine, long carbon chain diacid and terephthalic acid, and has a melting point of 190-320℃; the long carbon chain diacid is selected from one or more of sebacic acid, undecanedioic acid, dodecanedioic acid, tridecanedioic acid, tetradecanedioic acid, pentadecanedioic acid, hexadecanedioic acid, heptadecanedioic acid and octadecanedioic acid.

9. The composite material of claim 8, wherein, the other diamines include one or more of butanediamine, hexanediamine, heptanediamine, octanediamine, nonanediamine, decanediamine, undecanediamine, dodecanediamine, tridecanediamine, tetradecanediamine, pentadecanediamine, hexadecanediamine; or, the polyamide resin is obtained by copolymerization of pentanediamine, adipic acid and terephthalic acid, and has a melting point of 240-320℃; or, the polyamide resin is obtained by copolymerization of pentanediamine, hexanediamine, adipic acid and terephthalic acid, and has a melting point of 230-320℃.

10. A method of producing the fiber-reinforced composite material according to any one of claims 1 to 9, comprising molding a plurality of layers to produce the fiber-reinforced composite material; wherein, the multilayer structure includes one or more layers of polyamide sheet and one or more layers of fiber fabric.

11. The production method according to claim 10, wherein the compression molding process includes preheating the multilayer structure at 0-1 MPa for 5-10 min, followed by exhaust, and maintaining at a pressure of 5-8 MPa for 6-9 min, wherein the temperature during the compression molding process is maintained at 20-100℃ above the melting point of the polyamide sheet; and / or, the multilayer structure includes a first skin layer, at least one intermediate layer and a second skin layer arranged in sequence, the first skin layer and the second skin layer are both polyamide sheets, and the at least one intermediate layer includes fiber fabric.

12. Use of a polyamide sheet in the preparation of a fibre-reinforced composite material, wherein, The fiber-reinforced composite is produced by a laminate molding process, and the polyamide sheet has a viscosity of 1000 Pa-s or less at 200 to 340°C under a shear rate of 1 s -1 -1.

13. A polyamide plate comprising the fiber-reinforced composite material of any one of claims 1 to 9 or prepared by the method of claim 10 or 11.

14. A product comprising the polyamide plate of claim 13.

15. The product of claim 14, which is a molded article.

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