Prepreg and composite board

Abstract

The invention relates to a prepreg and a composite board, the prepreg comprises plant fiber cloth and a resin composition attached to the plant fiber cloth, the resin composition comprises thermoplastic resin, thermosetting resin and a curing agent, and the electronegativity difference value of atoms in polar groups at the tail end of a main chain of the thermoplastic resin is 0.4-1.7. The composite board prepared from the prepreg can be recycled, and has excellent mechanical properties and damp-heat aging resistance at the same time.

Description

Technical Field

[0001] The present invention relates to the technical field of the electronics industry, and particularly to prepregs and composite boards. Background Art

[0002] At present, commercially available resin-based composite materials are mainly glass fiber reinforced epoxy resin composite materials, but they have the problem of being unable to be recycled. Plant fiber reinforced composite materials have been widely used in fields such as aerospace, automotive, and consumer electronics due to their many advantages such as recyclability and environmental friendliness. However, as a biomass material, plant fibers have a large number of hydroxyl groups on the surface, resulting in a relatively high surface polarity and poor compatibility with the resin matrix, so that the bonding between plant fibers and the resin matrix is poor, resulting in low mechanical properties of the manufactured composite materials; at the same time, due to the high water absorption characteristics of plant fibers themselves, the manufactured composite materials have poor resistance to hygrothermal aging. Summary of the Invention

[0003] Based on this, in view of the above problems, it is necessary to provide a prepreg and a composite board, and the composite board prepared from the prepreg can be recycled, and at the same time has excellent mechanical properties and resistance to hygrothermal aging.

[0004] A prepreg includes a plant fiber cloth and a resin composition attached to the plant fiber cloth. The resin composition includes a thermoplastic resin, a thermosetting resin, and a curing agent. Among them, the electronegativity difference of atoms in the polar group at the end of the main chain of the thermoplastic resin is 0.4 - 1.7.

[0005] In one embodiment, the electronegativity difference of atoms in the polar group at the end of the main chain of the thermoplastic resin is 0.6 - 1.7.

[0006] In one embodiment, the thermoplastic resin is selected from at least one of acrylonitrile-butadiene-styrene terpolymer, polycarbonate resin, polyvinyl chloride resin, phenoxy resin, and polyamide resin.

[0007] In one embodiment, the microfibril angle of the plant fiber cloth is 4° - 15°;

[0008] and / or, the areal density of the plant fiber cloth is 90 g / m 2 -160 g / m 2 .

[0009] In one embodiment, the content of active hydroxyl groups on the surface of the plant fiber cloth is 80 gKOH / g - 200 mgKOH / g.

[0010] In one embodiment, the thermosetting resin has reactive groups, and the reactive groups form chemical bonds with the surface of the plant fiber cloth. The reactive groups are selected from at least one of epoxy groups, ester groups, or carboxyl groups.

[0011] In one embodiment, the thermosetting resin is selected from at least one of epoxy resins, polyester resins, or phenolic resins.

[0012] In one embodiment, the curing agent structure contains at least one of hexahydrotriazine bonds, disulfide bonds, unsaturated six-membered rings, or acetal bonds.

[0013] In one embodiment, the curing agent is selected from at least one of trifunctional amine curing agents containing a hexahydrotriazine structure, curing agents containing an unsaturated six-membered ring, amine curing agents containing a disulfide bond, or amine curing agents containing an acetal structure.

[0014] In one embodiment, the thermoplastic resin is 40 parts by weight - 70 parts by weight, the thermosetting resin is 30 parts by weight - 60 parts by weight, and the curing agent is 0.1 parts by weight - 5 parts by weight.

[0015] In one embodiment, the resin composition further includes a filler, and the filler is 10 parts by weight - 20 parts by weight.

[0016] In one embodiment, the filler is selected from hydrophobic fillers, and the contact angle of the hydrophobic filler is greater than 100°.

[0017] A composite board prepared by using the prepreg as described above.

[0018] In the present invention, using the plant fiber cloth as the reinforcing material, by using the thermoplastic resin and the thermosetting resin in combination, the prepared composite board can be recycled; at the same time, by using the thermoplastic resin and the thermosetting resin in combination and defining the electronegativity difference of the atoms in the polar groups at the end of the main chain of the thermoplastic resin, the thermoplastic resin has a high polarity, which can effectively improve the bonding property between the thermoplastic resin and the plant fiber cloth, thereby improving the mechanical properties and the resistance to damp heat aging of the composite board. Therefore, the composite board of the present invention can be recycled and has excellent mechanical properties and resistance to damp heat aging. Detailed Embodiments

[0019] To facilitate the understanding of the present invention, the present invention will be described in more detail below. However, it should be understood that the present invention can be implemented in many different forms and is not limited to the embodiments or examples described herein. On the contrary, the purpose of providing these embodiments or examples is to make the understanding of the disclosure of the present invention more thorough and comprehensive.

[0020] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the technical field to which this invention belongs. The terms used in the description of the present invention herein are for the purpose of describing specific embodiments or examples only, and are not intended to limit the present invention.

[0021] A prepreg provided by the present invention includes a plant fiber cloth and a resin composition attached to the plant fiber cloth. The resin composition includes a thermoplastic resin, a thermosetting resin, and a curing agent. Among them, the electronegativity difference of atoms in the polar group at the end of the main chain of the thermoplastic resin is 0.4 - 1.7.

[0022] In the present invention, using a plant fiber cloth instead of a glass fiber cloth as a reinforcing material can make the prepared composite board have recyclable and environmentally friendly properties.

[0023] The thermoplastic resin has good toughness, recyclability, and recyclability. However, the thermoplastic resin layer has poor rigidity. At the same time, the polarity difference between the thermoplastic resin and the surface of the plant fiber cloth is large. Moreover, the abundant hydroxyl groups and intramolecular hydrogen bonds in the plant fiber will cause uneven distribution in the thermoplastic resin matrix during heating, resulting in poor hygrothermal aging resistance and mechanical properties of the composite board; while the thermosetting resin has excellent hygrothermal aging resistance and relatively good mechanical properties, but the adhesion between the thermosetting resin and the plant fiber cloth is poor, resulting in poor mechanical properties of the composite board.

[0024] Therefore, in the resin composition of the present invention, the thermoplastic resin and the thermosetting resin are used in combination. Among them, the thermosetting resin forms a polymer with a dense three-dimensional network cross-linked structure under the action of a curing agent, so as to synergistically utilize the characteristics of the two resins and improve the mechanical properties and hygrothermal aging resistance of the composite board.

[0025] Moreover, by defining the electronegativity difference of atoms in the polar group at the end of the main chain of the thermoplastic resin to be 0.4 - 1.7, the thermoplastic resin has a higher polarity, reducing the polarity difference between the thermoplastic resin and the surface of the plant fiber cloth, improving the compatibility between the thermoplastic resin and the plant fiber cloth, thereby improving the bonding force between the thermoplastic resin and the plant fiber cloth, and further improving the mechanical strength and hygrothermal aging resistance of the composite board.

[0026] Therefore, the composite board of the present invention can be recycled, and at the same time has excellent mechanical properties and hygrothermal aging resistance.

[0027] It can be understood that the electronegativity difference of atoms in the polar group at the end of the main chain of the thermoplastic resin in the present invention refers to the electronegativity difference between different atoms in the terminal polar group. For example, when the terminal polar group is -OH, the electronegativity difference of atoms in the terminal polar group refers to the electronegativity difference between the oxygen atom and the hydrogen atom.

[0028] Understandably, each atom has a corresponding electronegativity value, and it can be directly obtained from the electronegativity data table of atoms disclosed in the prior art. Therefore, the electronegativity difference of the atoms in the polar group at the end of the main chain of the thermoplastic resin in the present invention can be directly calculated through the corresponding electronegativity values of the atoms. Optionally, the electronegativity difference of the atoms in the polar group at the end of the main chain of the thermoplastic resin is 0.6 - 1.7, which can further improve the polarity of the thermoplastic resin, making the binding force between the thermoplastic resin and the polar groups such as hydroxyl, carboxyl, amino, and thiol groups on the surface of the plant fiber more significant, thereby further improving the binding force between the thermoplastic resin and the surface of the plant fiber cloth and improving the mechanical properties of the composite board.

[0029] Optionally, the thermoplastic resin is selected from at least one of acrylonitrile - butadiene - styrene terpolymer, polycarbonate resin, polyvinyl chloride resin, phenoxy resin, and polyamide resin.

[0030] Optionally, the microfibril angle of the plant fiber cloth is 4° - 15°. With such a setting, while further improving the binding property between the plant fiber and the thermoplastic resin and the thermosetting resin, the tensile strength of the composite board can be improved, thereby improving the mechanical properties of the composite board.

[0031] It should be noted that the test method for the microfibril angle of the plant fiber cloth in the present invention: it is tested by X - ray diffraction method.

[0032] Optionally, the basis weight of the plant fiber cloth is 90 g / m 2 -160 g / m 2 . With such a setting, while further improving the structural strength of the composite board, the adhesion of the resin composition on the surface of the plant fiber cloth can be improved, thereby improving the binding force between the thermoplastic resin and the thermosetting resin and the plant fiber, and thus improving the mechanical properties and the resistance to damp - heat aging performance of the composite board.

[0033] In one embodiment, the plant fiber cloth is selected from at least one of ramie cloth, jute cloth, bamboo fiber cloth, hemp fiber cloth, nettle fiber cloth, wood fiber cloth, or linen cloth. Among them, ramie fiber has relatively excellent tensile properties. Therefore, ramie cloth is preferably used in the present invention.

[0034] Optionally, the content of active hydroxyl groups on the surface of the plant fiber cloth is 80 mgKOH / g - 200 mgKOH / g. With such a setting, by controlling the content of active hydroxyl groups on the surface of the plant fiber cloth, the polarity difference between the surface of the plant fiber cloth and the thermoplastic resin and the thermosetting resin can be further controlled, and at the same time, the water absorption of the plant fiber cloth itself can be controlled, so as to better improve the mechanical properties and the resistance to damp - heat aging performance of the composite board.

[0035] It should be noted that the content of active hydroxyl groups on the surface of the plant fiber cloth itself in the present invention is 80mgKOH / g - 200mgKOH / g. Alternatively, the content of active hydroxyl groups on the surface of the plant fiber cloth can be controlled to be 80mgKOH / g - 200mgKOH / g by means of surface treatment.

[0036] In one embodiment, the surface treatment method can be any one of an alkali treatment method, a plasma surface treatment method, a silane coupling agent treatment method, or an isocyanate treatment method.

[0037] Considering the bonding force between the thermosetting resin and the surface of the plant fiber cloth, the present invention preferably has the thermosetting resin having reactive functional groups, and the reactive functional groups form chemical bond bonding with the surface of the plant fiber cloth, and the reactive functional groups are selected from at least one of an epoxy group, an ester group, or a carboxyl group. With such a setting, the active group can react with groups such as hydroxyl groups on the surface of the plant fiber to form chemical bonds, thereby enabling chemical bond connection between the resin matrix and the plant fiber cloth, further improving the bonding force between the resin matrix and the plant fiber cloth, and improving the mechanical properties and moisture and heat aging resistance of the composite board.

[0038] Furthermore, the thermosetting resin is selected from at least one of an epoxy resin, a polyester resin, or a phenolic resin, wherein the epoxy resin is selected from at least one of a bisphenol A epoxy resin, a bisphenol F epoxy resin, a polyphenolic glycidyl ether epoxy resin, or an aliphatic glycidyl ether epoxy resin.

[0039] In the present invention, a corresponding curing agent can be selected according to the system of the thermosetting resin. At the same time, considering that conventional thermosetting resins, such as epoxy resins, are difficult to be degraded due to their dense three-dimensional network structure and will affect the recovery rate of the composite board, in the present invention, the curing agent structure contains at least one of a hexahydrotriazine bond, a disulfide bond, an unsaturated six-membered ring, or an acetal bond.

[0040] Furthermore, the curing agent is selected from at least one of a trifunctional amine curing agent containing a hexahydrotriazine structure, a diamine curing agent containing an unsaturated six-membered ring, an amine curing agent containing a disulfide bond, or an amine curing agent containing an acetal structure.

[0041] In one embodiment, the curing agent can also be modified from a conventional curing agent (such as dicyandiamide, phenol formaldehyde, diaminodiphenyl sulfone), that is, introducing a hexahydrotriazine bond, a disulfide bond, an unsaturated six-membered ring, or an acetal bond.

[0042] With such a setting, a specific curing agent is selected according to the system of the thermosetting resin to modify the thermosetting resin, so that the modified thermosetting resin contains structures such as hexahydrotriazine bonds and disulfide bonds and has degradability, thereby further improving the recovery rate of the composite board.

[0043] Optionally, by weight, the thermoplastic resin is 40 parts by weight - 70 parts by weight, the thermosetting resin is 30 parts by weight - 60 parts by weight, and the curing agent is 0.1 parts by weight - 5 parts by weight. By controlling the amounts of the thermoplastic resin, the thermosetting resin, and the curing agent, the mechanical properties of the composite board can be further improved while the moisture and heat aging resistance of the composite board is improved.

[0044] Optionally, the resin composition further includes a filler, and the filler is 10 parts by weight - 20 parts by weight. With such a setting, the mechanical properties of the composite board can be further improved.

[0045] Further, the filler is selected from hydrophobic fillers, and the contact angle of the hydrophobic filler is greater than 100°, preferably 120° - 180°. The addition of this hydrophobic filler, on the one hand, can reduce the rate of water diffusing into the plant fiber cloth and the resin matrix, avoid the cleavage between the plant fiber cloth and the resin matrix caused by the absorption of water by the plant fiber cloth, and thus improve the moisture and heat aging resistance of the composite board; on the other hand, it enables more polar groups (such as hydroxyl groups) in the plant fiber to combine with the resin matrix, thereby further improving the mechanical properties of the composite board.

[0046] It should be noted that in the present invention, the test method for the contact angle is the dynamic contact angle measurement method, that is, using a high-speed camera instrument to record the process of the liquid droplet spreading and contracting on the surface of the object to obtain the contact angle.

[0047] Further, the hydrophobic filler is selected from silica powder and / or silicon carbide powder.

[0048] Meanwhile, the present invention also provides a composite board prepared by using the above-mentioned semi-curing. This composite board can be recycled and has excellent mechanical properties and moisture and heat aging resistance.

[0049] In one embodiment, the preparation method of the composite board of the present invention includes:

[0050] S1, providing at least one semi-cured sheet, and the semi-cured sheet is the above-mentioned semi-cured sheet;

[0051] S2, stacking at least one semi-cured sheet to form a prefabricated board;

[0052] S3, respectively disposing release films on the two opposite surfaces of the prefabricated board, then disposing a substrate on the surface of the release film, and removing the substrate and the release film after hot pressing to obtain the composite board.

[0053] In step S1, the preparation method of the prepreg includes the following steps:

[0054] S11, provide a plant fiber cloth;

[0055] S12, mix the resin composition and the solvent evenly to obtain a glue solution, wherein the resin composition includes a thermoplastic resin, a thermosetting resin, and a curing agent;

[0056] S13, attach the glue solution to the surface of the plant fiber cloth, and obtain a prepreg after drying, wherein the drying temperature is 100°C - 220°C, and the drying time is 1 min - 5 min.

[0057] In an embodiment, in step S12, the solvent is N,N-dimethylformamide (DMF) solvent.

[0058] In step S12, by weight, the thermoplastic resin is 40 parts by weight - 70 parts by weight, the thermosetting resin is 30 parts by weight - 60 parts by weight, and the curing agent is 0.1 part by weight - 5 parts by weight.

[0059] Optionally, in step S12, a filler is further added, and the filler is 10 parts by weight - 20 parts by weight.

[0060] It can be understood that in step S2, the prefabricated board can be formed by selecting one prepreg according to actual needs, such as according to factors such as the required thickness of the composite board, or can be formed by stacking 2, 3, or 4 or more prepregs.

[0061] In step S3, the substrate is preferably a stainless steel plate.

[0062] It should be noted that the release film refers to a film with a separating property on the surface. The release film has no adhesiveness or has slight adhesiveness after contacting with a specific material under limited conditions. For example, the release film can be a PET polyester transparent anti-adhesive film, etc.

[0063] In step S3, the hot pressing temperature is 100°C - 170°C, the hot pressing pressure is 1 MPa - 4 MPa, and the hot pressing time is 0.5 h - 2 h.

[0064] Hereinafter, the prepreg and the composite board will be further described through the following specific examples.

[0065] At the same time, it should be noted that the raw materials involved in the examples and comparative examples in the present invention can all be obtained through market purchase.

[0066] Example 1

[0067] Mix 60 parts by weight of acrylonitrile-butadiene-styrene terpolymer (ABS) resin (model A304890, manufacturer is Aladdin Biochemical Technology Co., Ltd., the electronegativity difference of atoms in the terminal cyano group is 0.5), 40 parts by weight of 901 epoxy resin, 2.6 parts by weight of curing agent dicyandiamide (DCD), 15 parts by weight of silicon carbide micropowder (contact angle is 112°), and 40 parts by weight of DMF solvent to obtain a glue solution.

[0068] Coat the glue solution on the surface of ramie cloth (microfibril angle is 7.5°, surface density is 130 g / m 2 , and the content of surface-active hydroxyl groups is 105 mg KOH / g), and dry it at 170 °C for 2 min to obtain a semi-cured sheet.

[0069] Take 3 pieces of the semi-cured sheets obtained above and stack them to form a prefabricated board. Attach release films to two opposite surfaces of the prefabricated board, then stack stainless steel plates on the release films, and then place them in a laminating press. After pressing at a temperature of 150 °C and a pressure of 2.5 MPa for 1 h, remove the stainless steel plates and release films to obtain a composite board.

[0070] Example 2

[0071] Mix 50 parts by weight of polycarbonate resin (model P858524, manufacturer is Shanghai Macklin Biochemical Technology Co., Ltd., the electronegativity difference of atoms in the terminal ester group is 0.89), 50 parts by weight of polyester resin (model H997295, manufacturer is Shanghai Macklin Biochemical Technology Co., Ltd.), 3 parts by weight of curing agent dicyandiamide (DCD), 18 parts by weight of silicon carbide micropowder (contact angle is 112°), and 45 parts by weight of DMF solvent to obtain a glue solution.

[0072] Coat the glue solution on the surface of linen cloth (microfibril angle is 2.9°, surface density is 147 / m 2 , and the content of surface-active hydroxyl groups is 155 mg KOH / g), and dry it at 150 °C for 3 min to obtain a semi-cured sheet.

[0073] Take 3 pieces of the semi-cured sheets obtained above and stack them to form a prefabricated board. Attach release films to two opposite surfaces of the prefabricated board, then stack stainless steel plates on the release films, and then place them in a laminating press. After pressing at a temperature of 120 °C and a pressure of 2 MPa for 1.5 h, remove the stainless steel plates and release films to obtain a composite board.

[0074] Example 3

[0075] Mix 70 parts by weight of polyamide (model P111447, manufactured by Shanghai Aladdin Biochemical Technology Co., Ltd., with an electronegativity difference of 1.4 among the atoms in the terminal hydroxyl groups), 30 parts by weight of phenolic resin (model M87518-500G, manufactured by Shanghai Merck Chemical Technology Co., Ltd.), 0.5 part by weight of curing agent 3,3'-diaminodiphenyl sulfone (DDS), 12 parts by weight of silica powder (contact angle of 112°), and 20 parts by weight of DMF solvent to obtain a glue solution.

[0076] Coat the glue solution on the surface of jute cloth (microfibril angle of 8°, surface density of 156 g / m 2 , and the content of surface-active hydroxyl groups is 174 mg KOH / g), and dry it at 120 °C for 4 min to obtain a prepreg.

[0077] Take 3 pieces of the prepregs obtained above and stack them to form a prefabricated board. Attach release films to two opposite surfaces of the prefabricated board, then stack stainless steel plates on the release films, and then place them in a laminating press. After pressing at a temperature of 170 °C and a pressure of 2 MPa for 0.5 h, remove the stainless steel plates and release films to obtain a composite board.

[0078] Example 4

[0079] Compared with Example 1, Example 4 is only different in that the microfibril angle of ramie cloth is 4.2°, the surface density is 130 g / m 2 , and the content of surface-active hydroxyl groups is 98 mg KOH / g. The other conditions are the same, and a composite board is obtained.

[0080] Example 5

[0081] Compared with Example 1, Example 5 is only different in that the microfibril angle of ramie cloth is 8.9°, the surface density is 130 g / m 2 , and the content of surface-active hydroxyl groups is 136 mg KOH / g. The other conditions are the same, and a composite board is obtained.

[0082] Example 6

[0083] Compared with Example 1, Example 6 is only different in that the microfibril angle of ramie cloth is 20°, the surface density is 130 g / m 2 , and the content of surface-active hydroxyl groups is 174 mg KOH / g. The other conditions are the same, and a composite board is obtained.

[0084] Example 7

[0085] Compared with Example 1, Example 7 is only different in that the surface density of ramie cloth is 70 g / m 2 , and the other conditions are the same, and a composite board is obtained.

[0086] Example 8

[0087] Example 8 is different from Example 1 only in that the areal density of the ramie cloth is 180 g / m 2 , and the other conditions are the same, obtaining a composite board.

[0088] Example 9

[0089] Example 9 is different from Example 1 only in that the ramie cloth is treated with alkali and the content of surface active hydroxyl groups is 84 mgKOH / g, and the other conditions are the same, obtaining a composite board.

[0090] Example 10

[0091] Example 10 is different from Example 1 only in that polybutadiene is used to replace 901 epoxy resin, and the other conditions are the same, obtaining a composite board.

[0092] Example 11

[0093] Example 11 is different from Example 1 only in that hexahydro-s-triazine tris(p-benzamidofatty amine) is used to replace the curing agent dicyandiamide (DCD), and the other conditions are the same, obtaining a composite board.

[0094] Example 12

[0095] Example 12 is different from Example 1 only in that 2,2-bis[4-(4-aminophenoxy)phenyl]propane is used to replace the curing agent dicyandiamide (DCD), and the other conditions are the same, obtaining a composite board.

[0096] Example 13

[0097] Example 13 is different from Example 1 only in that 4,4'-dithiobisbenzeneamine is used to replace the curing agent dicyandiamide (DCD), and the other conditions are the same, obtaining a composite board.

[0098] Example 14

[0099] Example 14 is different from Example 1 only in that calcium carbonate (contact angle of 90°) is used to replace silicon carbide micropowder (contact angle of 112°), and the other conditions are the same, obtaining a composite board.

[0100] Example 15

[0101] Example 15 is different from Example 1 only in that the filler silicon carbide micropowder is not added, and the other conditions are the same, obtaining a composite board.

[0102] Example 16

[0103] Example 16 is different from Example 2 only in that the filler silicon carbide micropowder is not added, and the other conditions are the same, obtaining a composite board.

[0104] Comparative Example 1

[0105] Compared with Example 1, Comparative Example 1 is different only in that 901 epoxy resin is not added, and 100 parts by weight of acrylonitrile-butadiene-styrene terpolymer (ABS) resin is used, and the remaining conditions are the same, and a composite board is obtained.

[0106] Comparative Example 2

[0107] Compared with Example 1, Comparative Example 2 is different only in that polyphenylene ether resin (model SA9000, manufacturer is Sabic) is used to replace acrylonitrile-butadiene-styrene terpolymer (ABS) resin. Among them, the electronegativity difference of atoms in the aromatic ring group at the main chain end of the polyphenylene ether resin is 0, and the remaining conditions are the same, and a composite board is obtained.

[0108] Comparative Example 3

[0109] Compared with Example 1, Comparative Example 3 is different only in that polyether resin (model 300N, manufacturer is Nantong Zimeng Chemical Co., Ltd.) is used to replace acrylonitrile-butadiene-styrene terpolymer (ABS) resin. Among them, the electronegativity difference of atoms in the aromatic group at the main chain end of the polyether resin is 1.9, and the remaining conditions are the same, and a composite board is obtained.

[0110] Comparative Example 4

[0111] Compared with Example 1, Comparative Example 4 is different only in that acrylonitrile-butadiene-styrene terpolymer (ABS) resin is not added, and 100 parts by weight of 901 epoxy resin is used, and the remaining conditions are the same, and a composite board is obtained.

[0112] The performance tests were carried out on the composite boards obtained in Examples 1-16 and Comparative Examples 1-4. The test results are shown in Table 1, where

[0113] Mechanical properties: The mechanical properties of the composite board are characterized by the tensile strength and peel strength under normal conditions; the tensile strength is tested according to GB / T 1447-2005; the peel strength is tested according to GB / T2792-1998;

[0114] Moisture and heat aging resistance performance: The moisture and heat aging resistance performance is characterized by the change value of the tensile strength under normal conditions and the tensile strength after aging treatment, that is, the change value of the tensile strength before and after aging;

[0115] Among them, the tensile strength after aging treatment: After the test sample is aged for 6 weeks under the conditions of 85 °C and 85% relative humidity, the tensile strength is tested according to the method of GB / T 1447-2005;

[0116] Recovery rate: Benzyl alcohol was selected as the solvent, NaOH provided the alkaline condition, and ZnCl2 was used as the promoter. Degradation was carried out under normal pressure at 190 °C. The specific process was as follows: First, NaOH and ZnCl2 were mixed in proportion and added to a three-necked flask, and then an appropriate amount of benzyl alcohol was added. Then, the condensate water switch was turned on, and the liquid in the flask was heated to boiling with a heating mantle until it reached 190 °C, and then the test sample was added to the reactor for degradation.

[0117] Table 1

[0118]

[0119]

[0120] Comparing the data of Examples 1-16 and Comparative Examples 1-4 in Table 1, it can be seen that in the present invention, plant fiber cloth is used as the reinforcing material, and by using thermoplastic resin and thermosetting resin in combination, the prepared composite board can be recycled; at the same time, by using thermoplastic resin and thermosetting resin in combination and limiting the electronegativity difference of atoms in the polar group at the end of the main chain of the thermoplastic resin, the thermoplastic resin has a higher polarity, which can effectively improve the bonding property between the thermoplastic resin and the plant fiber cloth, thereby improving the mechanical properties and moisture and heat aging resistance of the composite board, so that the composite board can reach a recovery rate of ≥ 60%, a tensile strength of ≥ 155 MPa under normal conditions, a peel strength of ≥ 4.0 N / cm, and a tensile change value before and after aging of ≤ 25 MPa.

[0121] The technical features of the above embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope described in this specification.

[0122] The above embodiments only represent several implementation manners of the present invention, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the invention patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several deformations and improvements can still be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the present invention patent should be subject to the appended claims.

Claims

1. A prepreg, characterized in that, It includes a plant fiber cloth and a resin composition attached to the plant fiber cloth. The resin composition includes a thermoplastic resin, a thermosetting resin, and a curing agent. Among them, the electronegativity difference of atoms in the polar group at the end of the main chain of the thermoplastic resin is 0.4 - 1.

7.

2. The prepreg according to claim 1, wherein The electronegativity difference of atoms in the polar group at the end of the main chain of the thermoplastic resin is 0.6 - 1.

7.

3. The prepreg according to claim 1, characterized in that, The thermoplastic resin is selected from at least one of acrylonitrile - butadiene - styrene terpolymer, polycarbonate resin, polyvinyl chloride resin, phenoxy resin, and polyamide resin.

4. The prepreg according to claim 1, characterized in that, The microfibril angle of the plant fiber cloth is 4° - 15°; And / or, the basis weight of the plant fiber cloth is 90 g / m 2 -160 g / m 2 .

5. The prepreg according to claim 1, wherein The content of surface - active hydroxyl groups on the plant fiber cloth is 80mgKOH / g - 200mgKOH / g.

6. The prepreg according to claim 1, wherein The thermosetting resin has reactive groups, and the reactive groups form chemical - bond bonding with the surface of the plant fiber cloth. The reactive groups are selected from at least one of epoxy groups, ester groups, or carboxyl groups.

7. The prepreg according to claim 6, wherein The thermosetting resin is selected from at least one of epoxy resins, polyester resins, or phenolic resins.

8. The prepreg according to claim 1, characterized in that, The curing agent structure contains at least one of hexahydro - s - triazine bonds, disulfide bonds, unsaturated six - membered rings, or acetal bonds.

9. The prepreg according to claim 8, wherein, The curing agent is selected from at least one of trifunctional amine curing agents containing a hexahydro - s - triazine structure, diamine curing agents containing an unsaturated six - membered ring, amine curing agents containing disulfide bonds, or amine curing agents containing an acetal structure.

10. The prepreg according to claim 1, wherein, By weight, the thermoplastic resin is 40 parts by weight - 70 parts by weight, the thermosetting resin is 30 parts by weight - 60 parts by weight, and the curing agent is 0.1 part by weight - 5 parts by weight.

11. The prepreg according to any one of claims 1-10, characterized in that, The resin composition further includes a filler, and the filler is 10 parts by weight - 20 parts by weight.

12. The prepreg according to claim 11, wherein The filler is selected from hydrophobic fillers, and the contact angle of the hydrophobic filler is greater than 100°.

13. A composite board prepared by using the prepreg according to any one of claims 1 - 12.

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