Recyclable bio-based epoxy resins, methods of making and using the same

Abstract

The application discloses a recyclable bio-based epoxy resin and a preparation method and application thereof, and relates to the technical field of epoxy resin, and specifically discloses the following steps: adding cashew phenol, an acid binding agent, a polymerization inhibitor and a catalyst into a reaction container; under the protection of nitrogen, a bio-based diacyl chloride is added dropwise under the condition of an ice water bath; after the reaction is completed, a cashew phenol-based epoxy intermediate is obtained by filtering and washing the crude product with water; the obtained cashew phenol-based epoxy intermediate, formic acid, a catalyst and hydrogen peroxide are added into a reaction container, and the reaction is carried out at 50-100 DEG C; the crude product is separated, washed with water, dried, and the solvent is removed to obtain a multifunctional cashew phenol-based epoxy monomer EP; the multifunctional cashew phenol-based epoxy monomer is blended with a curing agent and an ester exchange catalyst, and is cured to prepare the recyclable bio-based epoxy resin. The recyclable bio-based epoxy resin prepared by the application has excellent thermodynamic performance, can be used for reinforcing carbon fiber composite materials, and can realize recycling of the composite materials.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of organic materials, and in particular relates to a recyclable bio-based epoxy resin and a preparation method and application thereof. BACKGROUND

[0002] As one of the most important thermosetting resins, epoxy resins are ubiquitous in industrial production and daily life, and have excellent thermal stability, dimensional stability, creep resistance, electrical insulation, and solvent resistance, and are widely used in the fields of automobiles, aerospace, transportation, construction, electronic and electrical equipment, etc. Among them, bisphenol A glycidyl ether is the most widely used, accounting for about 90% of the market share of epoxy resins. However, bisphenol A glycidyl ether is derived from petroleum-based compounds, and has potential toxicity and carcinogenicity, and its large-scale use will exacerbate the energy and environmental crisis. Therefore, it is of great practical significance to develop green and environmentally friendly epoxy resins to replace bisphenol A glycidyl ether.

[0003] At present, a large number of bio-based resources such as vegetable oil, lignin and cardanol have been used to prepare bio-based epoxy resins. Among them, cardanol is a renewable resource extracted from natural cashew nut shell oil, which has the advantages of abundant source, good biocompatibility, environmental protection, low price, etc., and can be used to prepare various bio-based materials such as epoxy resins, plasticizers, antioxidants, coatings, etc. However, most of the current bio-based epoxy resins have the problems of non-recyclability and non-repeated processing. By introducing dynamic bonds in the epoxy monomer or curing agent, the bio-based epoxy resin can realize degradation, reprocessing and other characteristics. In addition, epoxy resins are widely used to prepare carbon fiber reinforced composites (CFRCs), and the recyclable bio-based epoxy resin can also be used for CFRCs, which can realize the recycling of composite materials, effectively avoid the consumption of petrochemical energy, reduce environmental pollution problems caused by material waste, and provide a new strategy for the sustainable development of epoxy resins. SUMMARY

[0004] The technical problem to be solved is to solve the problem of difficult recycling and degradation of petroleum-based epoxy resins, and the present application provides a recyclable bio-based epoxy resin and a preparation method and application thereof, and is applied to carbon fiber reinforced composites, which has important significance for the development of bio-based epoxy resins.

[0005] Technical solution: a preparation method of a recyclable bio-based epoxy resin, comprising the following steps: (1) adding cashew phenol, acid-binding agent, polymerization inhibitor and catalyst into a reaction container, wherein the molar ratio of cashew phenol to acid-binding agent is 1:1-3, the amount of polymerization inhibitor is 0.4wt.%-1.5wt.%, and the amount of catalyst is 1.0wt.%-3.0wt.%; nitrogen protection is carried out, and bio-based diacyl chloride is added dropwise under ice water bath condition, the molar ratio of cashew phenol to bio-based diacyl chloride is (2-3):1, the reaction is carried out at 20-40℃ for 2-8h, and after the reaction is completed, the crude product is filtered and washed with water to obtain a cashew phenol-based epoxy intermediate; (2) adding the obtained cashew phenol-based epoxy intermediate, formic acid, catalyst and 30wt.% concentrated hydrogen peroxide into a reaction container, wherein the amount of formic acid is 0.5wt.%-1.5wt.%, the amount of catalyst is 1.5wt.%-3.5wt.%, and the amount of hydrogen peroxide is 60wt.%-90wt.%, the reaction is carried out at 50-100℃ for 3-8h, the crude product is separated, washed with water, dried, and the solvent is removed to obtain a multi-functionality cashew phenol-based epoxy monomer EP; (3) blending the multi-functionality cashew phenol-based epoxy monomer with a curing agent and an ester exchange catalyst, and curing to prepare a recyclable bio-based epoxy resin; the amount of the curing agent is 30wt.%-70wt.% of the epoxy resin, and the amount of the ester exchange catalyst is 2wt.%-6wt.% of the epoxy resin.

[0006] The bio-based diacyl chloride in step (1) is at least one of malonyl chloride, succinyl chloride, adipoyl chloride and furan diacyl chloride, and the molar ratio of cashew phenol to bio-based diacyl chloride is preferably 2:1.

[0007] The acid-binding agent in step (1) is at least one of triethylamine, pyridine, sodium hydroxide, sodium acetate and potassium carbonate; the polymerization inhibitor is at least one of 4-methoxyphenol, hydroquinone, p-tert-butyl hydroquinone, 1,4-naphthoquinone, diphenylamine and benzidine; and the catalyst is at least one of 4-dimethylaminopyridine, triphenylphosphine, tetrabutyl titanate and p-toluenesulfonic acid.

[0008] The catalyst in step (2) is at least one of concentrated sulfuric acid, p-toluenesulfonic acid, solid heteropoly acid, sodium hydroxide, aluminum chloride and tetrafluoroboric acid.

[0009] The curing agent in step (3) is at least one of 4-methyl-6-hydrophthalic anhydride, maleic anhydride, phthalic anhydride, ethylenediamine, hexanediamine, diethylenetriamine, triethylenetetramine, diethylaminopropylamine and m-phenylenediamine.

[0010] The ester exchange catalyst in step (3) is at least one of 1,5,7-triazabicyclo[4.4.0]dec-5-ene, zinc acetylacetonate and triphenylphosphine.

[0011] The recyclable bio-based epoxy resin prepared by the method.

[0012] The application of the recyclable bio-based epoxy resin in preparing carbon fiber reinforced composite materials or coatings.

[0013] The application method is that the multifunctional cardanol-based epoxy monomer is blended with a curing agent and an ester exchange catalyst, then is coated on carbon fibers layer by layer, and is heated in stages to prepare a cardanol-based carbon fiber reinforced composite material under the condition of 10-30 MPa.

[0014] The heating in stages is heating at 100 DEG C for 1-2 h, heating at 120 DEG C for 1-3 h, and heating at 150 DEG C for 4-7 h.

[0015] Beneficial effects: (1) the multifunctional cardanol-based epoxy monomer is synthesized through substitution reaction and epoxidation reaction, the bio-based content is 100%, the epoxy value is high, and the petroleum-based resources are effectively saved, and the requirement of sustainable development is met; (2) the recyclable bio-based epoxy resin prepared by the application has excellent thermodynamic performance, can be used for reinforcing carbon fiber composite materials, and realizes recycling of the composite materials. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 Infrared spectrum of the cardanol-based succinate epoxy monomer;

[0017] Figure 2 Microstructure diagram of the composite material;

[0018] Figure 3 Synthesis route diagram of the cardanol-based adipate epoxy monomer;

[0019] Figure 4 Microstructure diagram of the carbon fiber after chemical degradation. DETAILED DESCRIPTION

[0020] The following examples of the application are only used as further illustration of the content of the application, and cannot be used as limited content or range of the application. The application is further described in detail below in combination with detailed examples.

[0021] Example 1

[0022] (1) cardanol, an acid-binding agent triethylamine (molar ratio 1:1), a polymerization inhibitor hydroquinone (0.4% of the weight of the raw material), and a catalyst 4-dimethylaminopyridine (1.0% of the weight of the raw material) are added into a reaction container, nitrogen protection is carried out, succinyl chloride is added dropwise under the condition of ice water bath (the molar ratio of cardanol to succinyl chloride is 2:1), and reaction is carried out at 40 DEG C for 5 h. After the reaction is completed, the crude product is filtered and washed with water to obtain a cardanol-based succinate epoxy intermediate;

[0023] (2) The obtained cardanol-based succinic ester epoxy intermediate is added into a reaction bottle with formic acid (0.5% of the weight of the raw material), a catalyst p-toluenesulfonic acid (1.5% of the weight of the raw material), and 30% hydrogen peroxide (60% of the weight of the raw material), and reacted at 60°C for 5h. The obtained crude product is subjected to liquid separation, water washing, drying, and removal of the solvent to obtain a multifunctional cardanol-based succinic ester epoxy monomer EP. The infrared spectrum of the structure of the obtained product is shown in Figure 1

[0024] (3) The multifunctional cardanol-based succinic ester epoxy monomer is blended with a curing agent 4-methyl-6-hydrophthalic anhydride (35wt.%, 48wt.%, and 60wt.% of the epoxy resin), and an ester exchange catalyst 1,5,7-triazabicyclodec-5-ene (2wt.%, 3.5wt.%, and 5wt.%), and cured to prepare a recyclable cardanol-based succinic ester epoxy resin. The curing formula and the mechanical property test results are shown in Table 1.

[0025] Table 1

[0026]

[0027] (4) The multifunctional cardanol-based succinic ester epoxy monomer is blended with a curing agent 4-methyl-6-hydrophthalic anhydride (35wt.%, 48wt.%, and 60wt.% of the epoxy resin), and an ester exchange catalyst 1,5,7-triazabicyclodec-5-ene (2wt.%, 3.5wt.%, and 5wt.%), and cured to prepare a recyclable cardanol-based succinic ester epoxy resin. The curing formula and the mechanical property test results are shown in Table 1. Figure 2

[0028] Example 2

[0029] (1) Cardanol is added into a reaction container with an acid-binding agent pyridine (molar ratio 1:1.5), a polymerization inhibitor hydroquinone (0.5% of the weight of the raw material), and a catalyst triphenylphosphine (1.5% of the weight of the raw material), and protected by nitrogen gas. Hexanedioyl chloride is added dropwise under ice water bath conditions (molar ratio of cardanol to hexanedioyl chloride is 2.2:1), and reacted at 40°C for 5h. After the reaction is completed, the crude product is subjected to filtration and water washing to obtain a cardanol-based adipate ester epoxy intermediate;

[0030] ​​(2) The obtained cardanol-based adipate epoxy intermediate is added into a reaction bottle with formic acid (0.7% of the weight of the raw material), catalyst p-toluene sulfonic acid (2% of the weight of the raw material), 30% hydrogen peroxide (65% of the weight of the raw material), and is reacted at 50°C for 4h. The obtained crude product is subjected to liquid separation, water washing, drying, and removal of the solvent to obtain a multifunctional cardanol-based adipate epoxy monomer EP, and the synthesis route is as shown in Figure 3

[0031] (3) The multifunctional cardanol-based adipate epoxy monomer is blended with a curing agent maleic anhydride (37wt.%, 50wt.%, 62wt.% of the epoxy resin), and an ester exchange catalyst zinc acetylacetonate (2.2wt.%, 3.0wt.%, 3.7wt.%), and is cured to prepare a recyclable cardanol-based adipate epoxy resin, and the curing formula and mechanical property test results are shown in Table 2.

[0032] Table 2

[0033]

[0034] (4) The multifunctional cardanol-based adipate epoxy monomer is blended with a curing agent maleic anhydride (37wt.%, 50wt.%, 62wt.% of the epoxy resin), and an ester exchange catalyst zinc acetylacetonate (2.2wt.%, 3.0wt.%, 3.7wt.%), and is coated on carbon fibers layer by layer, and is subjected to stage heating, epoxy at 100°C for 2h, epoxy at 120°C for 1h, epoxy at 150°C for 2h, and is subjected to hot pressing at 20MPa to prepare a recyclable cardanol-based carbon fiber reinforced composite material.

[0035] Example 3

[0036] (1) Cardanol is added into a reaction container with an acid-binding agent sodium hydroxide (molar ratio 1:2), a polymerization inhibitor p-tert-butyl catechol (0.6% of the weight of the raw material), and a catalyst tetrabutyl titanate (1.5% of the weight of the raw material), and is dropped with furan dicarboxylic chloride (molar ratio of cardanol to furan carboxylic chloride is 2.1:1) under nitrogen protection and ice water bath conditions, and is reacted at 40°C for 6h. After the reaction is completed, the crude product is filtered and washed with water to obtain a cardanol-based furanate epoxy intermediate;

[0037] (2) The obtained cardanol-based furanate epoxy intermediate is added into a reaction bottle with formic acid (0.6% of the weight of the raw material), catalyst solid heteropoly acid (1.5% of the weight of the raw material), and 30% hydrogen peroxide (70% of the weight of the raw material), and is reacted at 50°C for 4h. The obtained crude product is subjected to liquid separation, water washing, drying, and removal of the solvent to obtain a multifunctional cardanol-based furanate epoxy monomer EP.

[0038] ​(3) The cardanol-based furanate epoxy monomer was blended with a curing agent phthalic anhydride (40 wt.%, 50 wt.%, 65 wt.% of the epoxy resin), an ester exchange catalyst 1,5,7-triazabicyclo[4.4.0]dec-5-ene (2.0 wt.%, 3.0 wt.%, 4.0 wt.%), and cured to prepare a cardanol-based furanate epoxy resin. The contact angle and solvent resistance of the obtained resin coating are shown in Table 3.

[0039] Table 3

[0040]

[0041] (4) After the cardanol-based furanate epoxy monomer was blended with a curing agent phthalic anhydride (40 wt.%, 50 wt.%, 65 wt.% of the epoxy resin), an ester exchange catalyst 1,5,7-triazabicyclo[4.4.0]dec-5-ene (2.0 wt.%, 3.0 wt.%, 4.0 wt.%), it was coated on carbon fibers layer by layer, and subjected to stage heating at 100°C for 1.5 h, at 120°C for 1.5 h, and at 150°C for 2.5 h, and hot pressing at 15 MPa to prepare a recyclable cardanol-based carbon fiber reinforced composite material.

[0042] Example 4

[0043] (1) Cardanol, an acid-binding agent sodium acetate (molar ratio 1:2.5), a polymerization inhibitor 1,4-naphthoquinone (0.7% of the weight of the raw material), and a catalyst p-toluenesulfonic acid (1.5% of the weight of the raw material) were added to a reaction vessel, and under nitrogen protection, malonyl chloride was added dropwise under ice water bath conditions (molar ratio of cardanol to malonyl chloride was 2.0:1), and the reaction was carried out at 20°C for 3 h. After the reaction was completed, the crude product was filtered and washed with water to obtain a cardanol-based malonate epoxy intermediate;

[0044] (2) The obtained cardanol-based malonate epoxy intermediate, formic acid (0.8% of the weight of the raw material), a catalyst sodium hydroxide (2.5% of the weight of the raw material), and 30% hydrogen peroxide (75% of the weight of the raw material) were added to a reaction bottle, and the reaction was carried out at 60°C for 4 h. The obtained crude product was separated, washed with water, dried, and the solvent was removed to obtain a multifunctional cardanol-based malonate epoxy monomer EP;

[0045] (3) The multifunctional cardanol-based malonate epoxy was blended with a curing agent hexamethylenediamine (35 wt.%, 48 wt.%, 60 wt.% of the epoxy resin), an ester exchange catalyst zinc acetylacetonate (2 wt.%, 3.5 wt.%, 5 wt.%), and cured to prepare a cardanol-based malonate epoxy resin. The performance of the cured resin coating film is shown in Table 4.

[0046] Table 4

[0047]

[0048] (4) The multifunctional cardanol-based malonate epoxy was blended with a curing agent, hexamethylene diamine (35 wt.%, 48 wt.%, 60 wt.% of the epoxy resin), and an ester exchange catalyst, zinc acetylacetonate (2 wt.%, 3.5 wt.%, 5 wt.%), and then coated on carbon fibers layer by layer. The temperature was raised in stages, and the sample was heated at 100°C for 1 h, at 120°C for 1.5 h, and at 150°C for 4.5 h. The sample was then hot-pressed at 25 MPa to prepare a recyclable cardanol-based carbon fiber-reinforced composite material.

[0049] Example 5

[0050] (1) Cardanol, an acid-binding agent, potassium carbonate (molar ratio 1:1.5), a polymerization inhibitor, diphenylamine (0.8% by weight of the raw material), and a catalyst, p-toluenesulfonic acid (2.2% by weight of the raw material), were added to a reaction vessel. Nitrogen was introduced into the reaction vessel, and succinyl chloride was added dropwise under ice water bath conditions (molar ratio of cardanol to succinyl chloride 2.4:1). The reaction was carried out at 35°C for 3 h. After the reaction was completed, the crude product was filtered and washed with water to obtain a cardanol-based succinate epoxy intermediate;

[0051] (2) The cardanol-based succinate epoxy intermediate obtained in step (1) was added to a reaction bottle along with formic acid (0.5% by weight of the raw material), a catalyst, aluminum trichloride (12.4% by weight of the raw material), and 30% hydrogen peroxide (80% by weight of the raw material). The reaction was carried out at 65°C for 5 h. The crude product obtained was separated, washed with water, dried, and the solvent was removed to obtain a multifunctional cardanol-based succinate epoxy monomer EP.

[0052] (3) The multifunctional cardanol-based succinate epoxy monomer was blended with a curing agent, diethylenetriamine (45 wt.% of the epoxy resin), and an ester exchange catalyst, zinc acetylacetonate (3.5 wt.%), and then cured to prepare a recyclable cardanol-based succinate epoxy resin. The tensile strength of the bio-based epoxy resin was 25.8 MPa, and the tensile strength of the recycled resin was 12.9 MPa.

[0053] (4) The multifunctional cardanol-based succinate epoxy monomer was blended with a curing agent, diethylenetriamine (45 wt.% of the epoxy resin), and an ester exchange catalyst, zinc acetylacetonate (3.5 wt.%), and then coated on carbon fibers layer by layer. The temperature was raised in stages, and the sample was heated at 100°C for 1 h, at 120°C for 1 h, and at 150°C for 4 h. The sample was then hot-pressed at 20 MPa to prepare a cardanol-based carbon fiber-reinforced composite material. The microstructure of the carbon fibers after degradation is shown in Figure 4 .

[0054] Example 6

[0055] (1) Cardanol was added to a reaction vessel with an acid-binding agent triethylamine (molar ratio 1:1.8), a polymerization inhibitor hydroquinone (0.8% by weight of the raw material), and a catalyst p-toluenesulfonic acid (2.5% by weight of the raw material), and nitrogen was introduced for protection. Hexanedioyl chloride was added dropwise under ice water bath conditions (molar ratio of cardanol to hexanedioyl chloride was 2.0:1), and the reaction was carried out at 35°C for 5h. After the reaction was completed, the crude product was filtered and washed with water to obtain a cardanol-based hexanedioate epoxy intermediate;

[0056] (2) The obtained cardanol-based hexanedioate epoxy intermediate was added to a reaction bottle with formic acid (0.6% by weight of the raw material), a catalyst tetrafluoroboric acid (1.8% by weight of the raw material), and 30% hydrogen peroxide (85% by weight of the raw material), and the reaction was carried out at 70°C for 5h. The obtained crude product was separated, washed with water, dried, and the solvent was removed to obtain a multifunctional cardanol-based hexanedioate epoxy monomer EP;

[0057] (3) The multifunctional cardanol-based hexanedioate epoxy monomer was blended with a curing agent m-phenylenediamine (50wt.% of the epoxy resin) and an ester exchange catalyst triphenylphosphine (2.5wt.%), and cured to prepare a bio-based epoxy resin. After the cured epoxy resin was cut, it was re-pressed and molded, and the recovery efficiency of the tensile strength could reach 67%;

[0058] (4) The multifunctional cardanol-based hexanedioate epoxy monomer was blended with a curing agent m-phenylenediamine (50wt.% of the epoxy resin) and an ester exchange catalyst triphenylphosphine (2.5wt.%), and then coated layer by layer on carbon fibers. Stage heating was carried out at 100°C for 1.5h, 120°C for 1.5h, and 150°C for 5h, and hot pressing was carried out at 25MPa to prepare a cardanol-based carbon fiber reinforced composite material.

[0059] Example 7

[0060] (1) Cardanol was added to a reaction vessel with an acid-binding agent pyridine (molar ratio 1:1.9), a polymerization inhibitor hydroquinone (0.4%-1.5% by weight of the raw material), and a catalyst 4-dimethylaminopyridine (1.5% by weight of the raw material), and nitrogen was introduced for protection. Furan diacid chloride was added dropwise under ice water bath conditions (molar ratio of cardanol to furan diacid chloride was 2.3:1), and the reaction was carried out at 25°C for 7h. After the reaction was completed, the crude product was filtered and washed with water to obtain a cardanol-based furanate epoxy intermediate;

[0061] (2) The obtained cardanol-based furanate epoxy intermediate was added with formic acid (0.8% of the weight of the raw material), catalyst concentrated sulfuric acid (1.5% of the weight of the raw material), 30% hydrogen peroxide (70% of the weight of the raw material) into a reaction bottle, and reacted at 50°C for 3h. The obtained crude product was separated by liquid-liquid extraction, washed with water, dried, and the solvent was removed to obtain a multifunctional cardanol-based furanate epoxy monomer EP;

[0062] (3) The multifunctional cardanol-based epoxy furanate epoxy monomer was blended with a curing agent 4-methyl-6-hydrophthalic anhydride (60wt.% of the epoxy resin), and an ester exchange catalyst zinc acetylacetate (1.5wt.%), and cured to prepare a bio-based epoxy resin. The scratch repair rate of the obtained resin coating can reach 89%;

[0063] (4) After the multifunctional cardanol-based epoxy furanate epoxy monomer was blended with a curing agent 4-methyl-6-hydrophthalic anhydride (60wt.% of the epoxy resin), and an ester exchange catalyst zinc acetylacetate (1.5wt.%), it was coated on carbon fibers layer by layer, and subjected to stage heating, heating at 100°C for 2h, heating at 120°C for 3h, and heating at 150°C for 6h. Hot pressing was performed at 25MPa to prepare a cardanol-based carbon fiber reinforced composite material. The mechanical and thermal properties are shown in Table 5.

[0064] Table 5

[0065]

[0066] Example 8

[0067] (1) Cardanol, an acid binding agent sodium hydroxide (molar ratio 1:1.2), a polymerization inhibitor p-tert-butyl catechol (1.4% of the weight of the raw material), and a catalyst tetrabutyl titanate (1.5% of the weight of the raw material) were added into a reaction container respectively, and nitrogen gas protection was performed. Malonyl chloride was added dropwise under ice water bath conditions (molar ratio of cardanol to malonyl chloride was 2.1:1), and the reaction was carried out at 30°C for 5h. After the reaction was completed, the crude product was filtered and washed with water to obtain a cardanol-based malonate epoxy intermediate;

[0068] (2) The obtained cardanol-based cardanol-based malonate epoxy intermediate was added with formic acid (1.2% of the weight of the raw material), a catalyst (3.5% of the weight of the raw material), and 30% hydrogen peroxide into a reaction bottle, and reacted at 65°C for 6h. The obtained crude product was separated by liquid-liquid extraction, washed with water, dried, and the solvent was removed to obtain a multifunctional cardanol-based malonate epoxy monomer EP;

[0069] (3) The multifunctional cardanol-based malonate epoxy monomer was blended with the curing agent maleic anhydride (the amount was 30 wt.%, 42 wt.%, 55 wt.% of the epoxy resin), the transesterification catalyst zinc acetylacetonate (1.0 wt.%, 2.0 wt.%, 2.5 wt.%), and then cured to prepare a bio-based epoxy resin. The solvent resistance of the obtained bio-based epoxy resin coating is shown in Table 6.

[0070] Table 6

[0071]

[0072] (4) The multifunctional cardanol-based malonate epoxy monomer was blended with the curing agent maleic anhydride (the amount was 30 wt.%, 42 wt.%, 55 wt.% of the epoxy resin), the transesterification catalyst zinc acetylacetonate (1.0 wt.%, 2.0 wt.%, 2.5 wt.%), and then coated on carbon fibers layer by layer, and then heated at 100°C for 2 h, 120°C for 2 h, and 150°C for 6 h, and then hot-pressed at 30 MPa to prepare a cardanol-based carbon fiber reinforced composite material.

[0073] Example 9

[0074] (1) Cardanol, an acid-binding agent potassium carbonate (molar ratio 1:1.4), a polymerization inhibitor diphenylamine (1.2% of the weight of the raw material), and a catalyst 4-dimethylaminopyridine (2.0% of the weight of the raw material) were added to a reaction vessel, and then succinyl chloride was added dropwise under nitrogen protection and ice water bath conditions (the molar ratio of cardanol to succinyl chloride was 2.4:1). The reaction was carried out at 35°C for 5 h. After the reaction was completed, the crude product was filtered and washed with water to obtain a cardanol-based succinate epoxy intermediate;

[0075] (2) The obtained cardanol-based succinate epoxy intermediate, formic acid (0.8% of the weight of the raw material), a catalyst tetrafluoroboric acid (1.7% of the weight of the raw material), and 30% hydrogen peroxide (85% of the weight of the raw material) were added to a reaction bottle, and then the reaction was carried out at 55°C for 5 h. The obtained crude product was separated, washed with water, dried, and then the solvent was removed to obtain a multifunctional cardanol-based succinate epoxy monomer EP;

[0076] (3) The multifunctional cardanol-based succinate epoxy monomer was blended with the curing agent triethylenetetramine (the amount was 48 wt.% of the epoxy resin), the transesterification catalyst triphenylphosphine (3.9 wt.%), and then cured to prepare a bio-based epoxy resin. The scratch self-repairing efficiency of the obtained bio-based epoxy resin coating can reach 92%.

[0077] (4) The multifunctional cardanol succinate epoxy monomer was blended with a curing agent triethylenetetramine (48 wt.% of the epoxy resin), an ester exchange catalyst triphenylphosphine (3.9 wt.%), and then coated on carbon fibers layer by layer, and then subjected to stage heating, heating at 100 °C for 1.5 h, heating at 120 °C for 2 h, heating at 150 °C for 5 h, and hot pressing under the condition of 10 MPa to prepare a cardanol-based carbon fiber reinforced composite material, and the tensile strength of the recovered carbon fiber can reach 150.8 MPa

[0078] Example 10

[0079] (1) Cardanol, an acid binding agent sodium hydroxide (molar ratio 1:1), a polymerization inhibitor benzidine (1.1% of the weight of the raw material), a catalyst, and triphenylphosphine (2.0% of the weight of the raw material) were added to a reaction vessel, and then hexanedioyl chloride was added dropwise under nitrogen protection and ice water bath conditions (the molar ratio of cardanol to hexanedioyl chloride was 2.2:1), and then the reaction was carried out at 40 °C for 3 h. After the reaction was completed, the crude product was filtered and washed with water to obtain a cardanol-based adipate epoxy intermediate;

[0080] (2) The obtained cardanol-based adipate epoxy intermediate, formic acid (0.7% of the weight of the raw material), a catalyst p-toluenesulfonic acid (2.5% of the weight of the raw material), and 30% hydrogen peroxide (90% of the weight of the raw material) were added to a reaction bottle, and then the reaction was carried out at 60 °C for 3.5 h. The obtained crude product was subjected to liquid separation, water washing, drying, and removal of the solvent to obtain a multifunctional cardanol-based adipate epoxy monomer EP;

[0081] (3) The multifunctional cardanol-based adipate epoxy monomer was blended with a curing agent 4-methyl-6-hydrophthalic anhydride (25 wt.%, 35 wt.%, and 45 wt.% of the epoxy resin) and an ester exchange catalyst zinc acetylacetonate (1.5 wt.%, 2.5 wt.%, and 3.5 wt.%), and then cured to prepare a bio-based epoxy resin, and the coating performance of which is shown in Table 7;

[0082] Table 7

[0083]

[0084] (4) The multifunctional cardanol-based adipate epoxy monomer was blended with a curing agent 4-methyl-6-hydrophthalic anhydride (25 wt.%, 35 wt.%, and 45 wt.% of the epoxy resin) and an ester exchange catalyst zinc acetylacetonate (1.5 wt.%, 2.5 wt.%, and 3.5 wt.%), and then coated on carbon fibers layer by layer, and then subjected to stage heating, heating at 100 °C for 1 h, heating at 120 °C for 1 h, heating at 150 °C for 4 h, and hot pressing under the condition of 15 MPa to prepare a recyclable cardanol-based carbon fiber reinforced composite material.

[0085] The present application is not limited to the above-described embodiments, and can be implemented as described in the summary and have the good effects described.

Claims

1. Process for the preparation of a recyclable bio-based epoxy resin, characterized in that, The method comprises the following steps: (1) adding cardanol, an acid-binding agent, a polymerization inhibitor and a catalyst into a reaction container, wherein the molar ratio of cardanol to the acid-binding agent is 1:1-3, the amount of the polymerization inhibitor is 0.4 wt.%-1.5 wt.%, and the amount of the catalyst is 1.0 wt.%-3.0 wt.%; under nitrogen protection, a biobased diacyl chloride is added dropwise under the condition of an ice water bath, the molar ratio of cardanol to the biobased diacyl chloride is (2-3):1, the reaction is carried out at 20-40℃ for 2-8 h, and after the reaction is completed, the crude product is filtered and washed with water to obtain a cardanol-based epoxy intermediate; (2) adding the obtained cardanol-based epoxy intermediate, formic acid, a catalyst and 30 wt.% hydrogen peroxide into a reaction container, wherein the amount of formic acid is 0.5 wt.%-1.5 wt.%, the amount of the catalyst is 1.5 wt.%-3.5 wt.%, and the amount of hydrogen peroxide is 60 wt.%-90 wt.%, the reaction is carried out at 50-100℃ for 3-8 h, the crude product is separated, washed with water, dried and the solvent is removed to obtain a multifunctional cardanol-based epoxy monomer EP; (3) blending the multifunctional cardanol-based epoxy monomer with a curing agent and an ester exchange catalyst, and curing to prepare a recyclable biobased epoxy resin, wherein the amount of the curing agent is 30 wt.%-70 wt.% of the epoxy resin, and the amount of the ester exchange catalyst is 2 wt.%-6 wt.% of the epoxy resin.

2. The method for preparing the recyclable bio-based epoxy resin according to claim 1, characterized in that, In step (1), the biobased diacyl chloride is at least one of malonyl chloride, succinyl chloride, adipoyl chloride and furan diacyl chloride, and the molar ratio of cardanol to the biobased diacyl chloride is 2:

1.

3. The method for preparing the recyclable bio-based epoxy resin according to claim 1, characterized in that, In step (1), the acid-binding agent is at least one of triethylamine, pyridine, sodium hydroxide, sodium acetate and potassium carbonate; the polymerization inhibitor is at least one of 4-methoxyphenol, hydroquinone, p-tert-butylcatechol, 1,4-naphthoquinone, diphenylamine and benzidine; and the catalyst is at least one of 4-dimethylaminopyridine, triphenylphosphine, tetrabutyl titanate and p-toluenesulfonic acid.

4. The method for preparing the recyclable bio-based epoxy resin according to claim 1, characterized in that, In step (2), the catalyst is at least one of concentrated sulfuric acid, p-toluenesulfonic acid, solid heteropoly acid, sodium hydroxide, aluminum chloride and tetrafluoroboric acid.

5. The method for preparing the recyclable bio-based epoxy resin according to claim 1, characterized in that, In step (3), the curing agent is at least one of 4-methyl-6-hydrophthalic anhydride, maleic anhydride, phthalic anhydride, ethylenediamine, hexanediamine, diethylenetriamine, triethylenetetramine, diethylaminopropylamine and m-phenylenediamine.

6. The method for preparing the recyclable bio-based epoxy resin according to claim 1, characterized in that, In step (3), the ester exchange catalyst is at least one of 1,5,7-triazabicyclo[4.4.0]dec-5-ene, zinc acetylacetonate and triphenylphosphine.

7. The recyclable biobased epoxy resin prepared by the method of any one of claims 1-6.

8. The use of the recyclable biobased epoxy resin of claim 7 in the preparation of carbon fiber reinforced composites or coatings.

9. Use according to claim 8, characterized in that, After the multifunctional cardanol-based epoxy monomer is blended with the curing agent and the ester exchange catalyst, the mixture is coated on carbon fibers layer by layer, and is heated in stages and hot-pressed at 10-30 MPa to prepare a cardanol-based carbon fiber reinforced composite material.

10. Use according to claim 9, characterized in that, The heating in stages comprises heating at 100℃ for 1-2 h, heating at 120℃ for 1-3 h and heating at 150℃ for 4-7 h.

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