Epoxy fiber composite material for wind turbine blades and method of making

Abstract

The wind power blade epoxy fiber composite material and preparation method relate to material technology and environmental protection technology, and the preparation method comprises the following steps: (1) preparation of glycidyl ester type epoxy resin: after mixing, the low molecular weight glycidyl ester type epoxy resin is reacted with a chain extender modifier, and the low molecular weight glycidyl ester type epoxy resin molecules are combined into high molecular weight glycidyl ester type epoxy resin molecules; (2) preparation of an epoxy resin composition: the glycidyl ester type epoxy resin prepared in the step (1) is uniformly mixed with an amine curing agent at room temperature to obtain the epoxy resin composition; (3) the epoxy resin composition is impregnated into inorganic fibers, and after drying, the wind power blade epoxy composite material is obtained. The wind power blade material has good mechanical properties, high heat resistance, low production cost, and is easy to recycle.

Description

TECHNICAL FIELD

[0001] The present application relates to material technology and environmental protection technology, in particular to a blade material of a wind power generator. BACKGROUND

[0002] With the increasing demand for clean energy, wind power has developed rapidly in recent years. Wind power blades are an important part of wind power generators, and their main materials are composed of resins (thermosetting resins: epoxy resin, unsaturated polyester, and thermoplastic resins: polyethylene terephthalate, polybutylene terephthalate, nylon, etc.) and reinforcing materials (glass fiber, carbon fiber, etc.). Among them, the epoxy resin / glass fiber composite material system has high mechanical properties, heat resistance, creep resistance, and low production cost, and is the largest system used in wind power blades.

[0003] The current ordinary thermosetting epoxy resin / glass fiber composite material system for wind power blades has the problems of difficult melting and difficult dissolution, making it difficult to recycle after retirement, causing serious waste of resources and environmental pollution. The main treatment methods for thermosetting plastics at present are landfill, grinding, burning and pyrolysis, which consume a large amount of energy and have poor economic benefits for recycling.

[0004] In order to explore the recycling scheme of blades, domestic and foreign researchers have proposed two solutions from the perspectives of raw materials and recycling technology: using thermoplastic resins and synthesizing new thermosetting resins containing degradable groups or structures.

[0005] Using thermoplastic resins: such as Cyclics' CBT 200 thermoplastic resin PBT (polybutylene terephthalate), Delft University of Technology's nylon 6, Arkema's Elium acrylic-based thermoplastic resin, Wanhua Chemical's "CN201811322671.4 A kind of thermoplastic epoxy resin composition and its application", "CN201911078712.4 A kind of crystalline thermoplastic epoxy resin curing product and its preparation method", etc. However, due to the relatively high viscosity of thermoplastic resins, the wettability of glass fiber or carbon fiber is not high, and the content of fiber reinforced materials is low, so the mechanical strength and other properties are insufficient.

[0006] Synthesizing new thermosetting resins containing degradable groups or structures: refers to synthesizing new thermosetting resins containing degradable groups or structures, mainly including introducing dynamic covalent bonds and degradable groups into thermosetting resins.

[0007] The introduced dynamic covalent bonds include ester bonds, imine bonds, acetal bonds, disulfide bonds, borate bonds, DA addition, etc. For example, Ludwik Leibler et al. reacted epoxy prepolymers with fatty acids or anhydrides to form ester bonds in the crosslinked network of epoxy resin, and the ester exchange reaction at high temperature changed and rearranged the topology of the network, thereby making the material have viscoelasticity and "flowability" (plasticity, reworkability). Ludwik Leibler defines the thermoset material with flow properties as "Vitrimer". Since the Vitrimer does not change the crosslinking point density during processing, its properties are similar to inorganic glass at high temperature, so Academician Zhang Xi of Tsinghua University named it "glass-like polymer"; Based on dynamic ester bonds, disulfide bonds, aromatic disulfide bonds, and D-A bonds, Chen Mao et al. constructed recyclable epoxy vitrimer materials, and their related patents include "CN201910974144.X A method for regulating the stress relaxation and reprocessing forming temperature of glass-like polymer materials by dynamic bond content", "CN201910974152.4 A preparation method of high-strength solvent-resistant fast disassemblable and recyclable epoxy fiber composite material", "CN201910059771.0 A preparation method of thermosetting polymer that can be welded, repaired and reprocessed at medium temperature", "CN202110483313.7 A fiber-reinforced epoxy glass-like polymer composite material wound and formed", "CN202110205291.8 An optoelectromagnetic response epoxy glass-like polymer", "CN202110205702.3 A medium-low temperature curing type epoxy glass-like polymer", etc.; Ma Songqi et al. from Ningbo Institute of Materials of Chinese Academy of Sciences studied itaconic acid-based epoxy, vanillin-based epoxy, eugenol-based epoxy, and epoxy resin glass-like polymer vitrimers (crosslinked network with exchangeable bonds), and applied for patents including invention "CN201810885870.X A degradable epoxy resin modified by spiral ring acetal and its preparation method and application", "CN201910202650.7 An epoxy monomer based on acetal structure and its preparation method and application", "CN109320918.A Recyclable carbon fiber reinforced epoxy resin composite material, its preparation method and application", etc. Professor Yao Zhen of College of Chemistry and Life Science of Zhejiang University "CN201810093351.X Method for preparing reusable epoxy resin by using bulk click chemistry reaction", "CN201810092901.6 Method for preparing reversible crosslinking toughened epoxy resin by using bulk click chemistry reaction": Click reaction has fast speed and high selectivity, which is an effective method for precise control of polymer chain structure.The method comprises the following steps: 1) obtaining an intermediate with a furan functional group at the end by click reaction of a multifunctional epoxy resin and furfuryl mercaptan under the action of a tertiary amine catalyst; and 2) Diels-Alder reaction of the intermediate and a crosslinking agent containing a maleimide group to form a reversibly crosslinked epoxy resin. CN108129638A A recyclable epoxy resin and a preparation method published by Wang Dong et al. of Aerospace Special Material and Process Technology Research Institute discloses that an amine curing agent with a dynamic imine bridge bond is synthesized and cured with an epoxy resin to prepare an epoxy resin with a dynamic bond. CN112608452A A high-performance recyclable and easily repaired epoxy resin and a preparation method discloses that an epoxy resin containing a dynamic borate bond is prepared by reaction of an organic amine molecule with a benzene boronic acid group at one end and a polyhydric alcohol molecule or by reaction of an organic amine molecule with a single diol group at one end and a polyhydric benzene boronic acid molecule.

[0008] In comparison, introducing a dynamic bond into an epoxy resin or curing the epoxy resin by using a reversible reaction is an effective method to solve the problem of recycling of the epoxy resin. However, the currently reported degradable and recyclable epoxy resins still have insufficient mechanical properties, heat resistance and other properties relative to ordinary epoxy resins, have high production costs, and many epoxy systems have high curing temperatures and large creep, which limits their application in the field of wind turbine blades. SUMMARY

[0009] The technical problem to be solved by the present application is to provide an easily recyclable epoxy fiber composite material for wind turbine blades to solve the problems of the prior art.

[0010] The technical solution adopted by the present application to solve the technical problem is that the epoxy fiber composite material for wind turbine blades comprises 10-30 parts by weight of an epoxy resin cured product, 70-90 parts by weight of inorganic fibers,

[0011] The inorganic fibers include any one of glass fibers, carbon fibers and basalt fibers;

[0012] The epoxy resin cured product includes any one of the following compounds:

[0013]

[0014]

[0015]

[0016] The R1 is a phenyl group, a cycloalkyl group or an alkyl group;

[0017] The R2 is a phenyl group, a cycloalkyl group or an alkyl group;

[0018] R3 is phenyl, cycloalkyl or alkyl;

[0019] R4 is phenyl, cycloalkyl or alkyl;

[0020] R5 is phenyl, cycloalkyl or alkyl;

[0021] R6 is phenyl, cycloalkyl or alkyl;

[0022] R7 is phenyl, cycloalkyl or alkyl;

[0023] R8 is phenyl, cycloalkyl or alkyl;

[0024] R9 is phenyl, cycloalkyl or alkyl;

[0025] R 10 is phenyl, cycloalkyl or alkyl.

[0026] The epoxy resin cured product is obtained by reacting glycidyl ester type epoxy resin with amine curing agent;

[0027] The glycidyl ester type epoxy resin is obtained by mixing 80wt%-98wt% of low molecular weight glycidyl ester type epoxy resin with 2wt%-20wt% of chain extender modifier and then reacting;

[0028] The low molecular weight glycidyl ester type epoxy resin is any one of tetrahydrophthalic glycidyl ester, hexahydrophthalic glycidyl ester or 4,5-epoxyhexane-1,2-diglycidyl ester,

[0029] The chain extender modifier is any one of amine chain extender, acid chain extender or alcohol chain extender.

[0030] The inorganic fiber includes at least two of glass fiber, carbon fiber and basalt fiber;

[0031] The amine curing agent includes any one of isophorone diamine, triethylene tetramine or 4,4-diamino diphenyl sulfone.

[0032] The application also provides a preparation method of the epoxy fiber composite material for wind power blades, including the following steps:

[0033] (1) Preparation of glycidyl ester type epoxy resin: after mixing the low molecular weight glycidyl ester type epoxy resin with the chain extender modifier and then reacting, the low molecular weight glycidyl ester type epoxy resin molecules are combined into high molecular weight glycidyl ester type epoxy resin molecules;

[0034] The low molecular weight glycidyl ester type epoxy resin is any one of tetrahydrophthalic glycidyl ester, hexahydrophthalic glycidyl ester or 4,5-epoxyhexane-1,2-diglycidyl ester,

[0035] The chain-extending modifier is an amine chain-extending modifier, an acid chain-extending modifier or an alcohol chain-extending modifier.

[0036] (2) Preparation of the epoxy resin composition: the glycidyl ester type epoxy resin prepared in step (1) is mixed with the amine curing agent at room temperature to obtain the epoxy resin composition;

[0037] (3) The inorganic fiber is impregnated with the epoxy resin composition, and after drying, the epoxy composite material for wind power blades is obtained.

[0038] In step (1), the viscosity of the mixture is controlled in the range of 3000-5000 mPa.s;

[0039] In step (2), the viscosity of the mixture is controlled in the range of 200-300 mPa.s.

[0040] Further, step (3) is: the inorganic fiber is impregnated with the epoxy resin composition under the pressure of 0.01-0.02 MPa, and then is placed under the pressure greater than 0.2 MPa, and after drying, the epoxy composite material for wind power blades is obtained.

[0041] In step (1), the low molecular weight glycidyl ester type epoxy resin is mixed in the proportion of 80wt%-98wt% and the chain-extending modifier is mixed in the proportion of 2wt%-20wt%.

[0042] The amine curing agent includes any one of isophorone diamine, triethylene tetramine and 4,4-diamino diphenyl sulfone.

[0043] The wind power blade material of the present application has good mechanical properties, high heat resistance and low production cost. The present application uses small molecules of low molecular weight to chain-extend into macromolecular structures, which increases the gel reaction time and provides great convenience for construction.

[0044] In particular, the wind power blade using the present application is easy to recycle. The epoxy resin / glass fiber composite material is degraded by high-boiling-point alcohol such as ethylene glycol, the glass fiber is separated, the degraded ethylene glycol epoxy solution is purified and separated, the dihydric alcohol part is used to synthesize epoxy resin again, and the polyhydric alcohol part is used as a flame retardant additive.

[0045] In summary, the recycling process of the present application is simple, has high recycling rate, no "three wastes" emission, is green and environmentally friendly, has low recycling cost and high economic efficiency. BRIEF DESCRIPTION OF DRAWINGS

[0046] Figure 1 is the heat resistance curve of the epoxy composition of the present application. DETAILED DESCRIPTION

[0047] The present application first utilizes low-cost glycidyl ester epoxy to prepare an epoxy resin composition, and uses the same to prepare an epoxy resin / glass fiber composite material.

[0048] The principle of the present application is:

[0049] First, a chain extension reaction is performed on glycidyl esters such as tetrahydrophthalic acid glycidyl ester and hexahydrophthalic acid glycidyl ester using an amine containing two active hydrogens such as aniline, an acid containing two carboxyl groups such as tetrahydrophthalic acid and hexahydrophthalic acid, or an alcohol containing two hydroxyl groups such as ethylene glycol and butanediol. By adjusting the molecular weight and reactivity of the glycidyl ester, the gel reaction time and reaction heat in the later stage can be adjusted, the workable time is increased, and the thermal stress is reduced.

[0050] Then, the chain-extended product is mixed with an amine curing agent such as isophorone diamine, p-phenylenediamine, polyether amine, and imidazole in a proper proportion, and a diluent such as epoxy propane butyl ether can be added to adjust the viscosity, to obtain an epoxy composition. Finally, the epoxy composition is combined with glass fiber cloth by a vacuum pressure infusion process to obtain a new type of epoxy fiber composite material.

[0051] The wind power blade material of the present application can be fully and low-cost recycled. The new epoxy / glass fiber composite material is cut into blocks, mixed with ethylene glycol, and heated to reflux, so that the epoxy resin in the material is degraded into an ethylene glycol solution, the main components of which are dihydroxy esters of tetrahydrophthalic acid and hexahydrophthalic acid, and nitrogen-containing polyols. The glass fiber in the composite material can be extracted by filtration. After the ethylene glycol solution is heated and concentrated, NaOH solution is added to hydrolyze the dihydroxy esters of tetrahydrophthalic acid and hexahydrophthalic acid into sodium salts of tetrahydrophthalic acid and hexahydrophthalic acid, then hydrochloric acid is added to convert the sodium salts into acids, and then the characteristics of tetrahydrophthalic acid and hexahydrophthalic acid that are insoluble in water and ethylene glycol are used to extract the tetrahydrophthalic acid and hexahydrophthalic acid by filtration. Then, epoxy chloropropane and quaternary ammonium salt are added to synthesize tetrahydrophthalic acid glycidyl ester and hexahydrophthalic acid glycidyl ester from the tetrahydrophthalic acid and hexahydrophthalic acid, so that the epoxy resin can be recycled. The remaining nitrogen-containing polyols can be used as flame retardant additives.

[0052] Embodiment of the preparation method:

[0053] The present application provides a preparation method of an epoxy composite material for wind power blades, comprising the following steps:

[0054] (1) Preparation of glycidyl ester type epoxy resin: first mix the low molecular weight glycidyl ester type epoxy resin with a modifier at room temperature, and place for 2 h, then react at 80℃ for 8 h, and control the viscosity of the mixture in the range of 3000-5000 mPa.s;

[0055] (2) Preparation of the epoxy resin composition: the glycidyl ester type epoxy resin prepared in step (1) is mixed with an amine curing agent, a diluent, a toughening agent at room temperature to form a mixture with a viscosity of 200-300 mPa.s;

[0056] (3) Preparation of the epoxy / fiber composite material: inorganic fibers are stacked in a vacuum pressure tank, vacuum is applied, and the vacuum pressure is controlled at 0.01-0.02 MPa. The epoxy resin composition prepared in step (2) is injected into the vacuum pressure tank, and is allowed to stand for 1-2 h. Then, the pressure of the vacuum pressure tank is raised to 0.4 MPa by high-pressure nitrogen, and is allowed to stand for 1-8 h. Finally, the temperature is raised to 80℃, and is allowed to stand for 1-8 h for curing.

[0057] The glycidyl ester type epoxy resin is prepared by mixing 80wt%-98wt% of a low molecular weight glycidyl ester type epoxy resin with 2wt%-20wt% of a modifier,

[0058] The low molecular weight glycidyl ester type epoxy resin is tetrahydrophthalic acid diglycidyl ester, hexahydrophthalic acid diglycidyl ester or 4,5-epoxyhexane-1,2-dicarboxylic acid diglycidyl ester,

[0059] The modifier is any one of aniline, tetrahydrophthalic acid, hexahydrophthalic acid.

[0060] The inorganic fibers include at least two of glass fibers, carbon fibers, basalt fibers.

[0061] The amine curing agent includes any one of isophorone diamine, triethylene tetramine, 4,4-diamino diphenyl sulfone.

[0062] Example 1

[0063] In this example, tetrahydrophthalic acid diglycidyl ester is used as a raw material, chain extension is first performed, an amine curing agent is added, etc. to form an epoxy mixture, and then the epoxy mixture is combined with inorganic fibers to be cured and formed to obtain a wind turbine blade material.

[0064] Chain extension can be achieved by using an amine chain extender, an acid chain extender or an alcohol chain extender, which are described as follows:

[0065] Reactant: tetrahydrophthalic acid diglycidyl ester, with the following structure:

[0066]

[0067] (A1) Chain extension is performed using an amine chain extender H2N-R1, with the following reaction formula:

[0068]

[0069] R1 is phenyl, cycloalkyl, alkyl, etc.

[0070] The product after chain extension reacts with an amine curing agent to form an epoxy cured product, and the reaction formula is as follows:

[0071]

[0072] R2 is phenyl, cycloalkyl, alkyl, etc.

[0073] (A2) Chain extension reaction with an acid chain extender:

[0074]

[0075] R3 is phenyl, cycloalkyl, alkyl, etc.

[0076] The product after chain extension reacts with an amine curing agent to form an epoxy cured product, and the reaction formula is as follows:

[0077] (A3) Chain extension reaction with an alcohol chain extender:

[0078]

[0079] R4 is phenyl, cycloalkyl, alkyl, etc.

[0080] The product after chain extension reacts with an amine curing agent to form an epoxy cured product, and the reaction formula is as follows:

[0081]

[0082] Example 2

[0083] In this example, hexahydrophthalic acid diglycidyl ester is used as raw material, chain extension is first performed, an amine curing agent is added, etc., to form an epoxy mixed solution, which is then compounded with inorganic fibers, cured and formed to obtain a wind turbine blade material.

[0084] Chain extension can be achieved by an amine chain extender, an acid chain extender or an alcohol chain extender, which are described as follows:

[0085] Reactant: hexahydrophthalic acid diglycidyl ester, with the structure

[0086]

[0087] (B1) Chain extension with an amine chain extender, with the reaction formula as follows:

[0088]

[0089] R5 is phenyl, cycloalkyl, alkyl, etc.

[0090] The chain-extended product is reacted with an amine curing agent to form an epoxy cured product, and the reaction formula is as follows:

[0091] (B2) chain extension reaction with an acid chain extender:

[0092]

[0093] R6 is phenyl, cycloalkyl, alkyl, etc.

[0094] The chain-extended product is reacted with an amine curing agent to form an epoxy cured product, and the reaction formula is as follows:

[0095]

[0096] (B3) chain extension reaction with an alcohol chain extender:

[0097]

[0098] R7 is phenyl, cycloalkyl, alkyl, etc.

[0099] The chain-extended product is reacted with an amine curing agent to form an epoxy cured product, and the reaction formula is as follows:

[0100]

[0101] Example 3

[0102] In this embodiment, 4,5-epoxyhexane-1,2-dicarboxylic acid diglycidyl ester is used as raw material, chain extension is first carried out, an amine curing agent is added, etc., to form an epoxy mixed solution, which is then compounded with inorganic fibers, and cured and formed to obtain a wind turbine blade material.

[0103] Chain extension can be achieved by amine chain extender, acid chain extender or alcohol chain extender, which is described as follows:

[0104] Reactant: 4,5-epoxyhexane-1,2-dicarboxylic acid diglycidyl ester, structural formula:

[0105]

[0106] (C1) chain extension with an amine chain extender, and the reaction formula is as follows:

[0107]

[0108] R8 is phenyl, cycloalkyl, alkyl, etc.

[0109] The chain-extended product is reacted with an amine curing agent to form an epoxy cured product, and the reaction formula is as follows:

[0110] (C2) Chain extension reaction with acid chain extender:

[0111]

[0112] R9 is phenyl, cycloalkyl, alkyl, etc.

[0113] The chain-extended product is reacted with an amine curing agent to form an epoxy cured product, and the reaction formula is as follows:

[0114]

[0115] (C3) Chain extension reaction with alcohol chain extender:

[0116]

[0117] R 10 is phenyl, cycloalkyl, alkyl, etc.

[0118] The chain-extended product is reacted with an amine curing agent to form an epoxy cured product, and the reaction formula is as follows:

[0119]

[0120] The epoxy / fiber composite material of the present application can be recycled and utilized at low cost: after crushing the epoxy / fiber composite material and adding ethylene glycol, high temperature reaction is carried out, then the inorganic fiber and ethylene glycol solution are separated, the inorganic fiber is dried to obtain surface-modified inorganic fiber, realizing the recycling and cyclic utilization of inorganic fiber in the composite material; the ethylene glycol filtrate is concentrated and then NaOH solution is added, and 12 mol / L concentrated hydrochloric acid solution is added after heating, and then filtered after cooling to room temperature, and the filtrate is separated by rectification to obtain ethylene glycol and water, and the remaining substance is a nitrogen-containing polyol which can be used as a flame retardant additive; the insoluble substance produced by filtration is dried, and the main components are dibasic acid and part of NaCl. After mixing the dried insoluble substance with epichlorohydrin and benzyl ammonium chloride, heating and refluxing, and then cooling and filtering to remove insoluble NaCl, the filtrate is added to NaOH solution, reacted, separated to remove the lower aqueous phase, and the upper organic phase is heated to 117°C to remove epichlorohydrin to obtain a low molecular weight glycidyl ester, realizing the complete recycling and cyclic utilization of the epoxy resin.

[0121] Experimental data:

[0122] 1. Tetrahydrophthalic glycidyl ester epoxy resin is cured with isophorone diamine (epoxy composition), and the curing conditions are: the mixture product is placed for 24 h, and cured at 80°C for 6 h;

[0123] (1) Mechanical properties of the epoxy composition body:

[0124]

[0125]

[0126]

[0127]

[0128] (2) Heat resistance see Figure 1 .

[0129] 2. Epoxy composition + glass fiber cloth (FRP plate): (1) Mechanical properties

[0130]

[0131]

[0132]

[0133]

Claims

1. A method of preparing an epoxy fiber composite material for wind turbine blades, characterized in that, The method comprises the following steps: (1) Preparation of high molecular weight glycidyl ester type epoxy resin: 80wt%-98wt% of low molecular weight glycidyl ester type epoxy resin is mixed with 2wt%-20wt% of chain extender modifier, and the mixture is reacted to control the viscosity in the range of 3000-5000 mPa·s, to obtain high molecular weight glycidyl ester type epoxy resin; The low molecular weight glycidyl ester type epoxy resin is tetrahydrophthalic glycidyl ester, and the chain extender modifier is amine chain extender, acid chain extender or alcohol chain extender; (2) Preparation of epoxy resin cured product: the high molecular weight glycidyl ester type epoxy resin prepared in step (1) is mixed with amine curing agent at room temperature to control the viscosity of the mixture in the range of 200-300 mPa·s, to obtain the epoxy resin cured product; (3) The epoxy resin cured product is impregnated with inorganic fibers under the air pressure of 0.01-0.02 MPa, and then is placed under the air pressure greater than 0.2 MPa, to obtain the epoxy composite material for wind power blades after drying; The weight ratio of the epoxy resin cured product to the inorganic fibers is 10-30 parts of the epoxy resin cured product to 70-90 parts of the inorganic fibers; the inorganic fibers include any one of glass fibers, carbon fibers and basalt fibers; the epoxy resin cured product includes any one of the following compounds: ； The R1 is phenyl, cycloalkyl or alkyl; The R2 is phenyl, cycloalkyl or alkyl; The R3 is phenyl, cycloalkyl or alkyl; The R4 is phenyl, cycloalkyl or alkyl.

2. The method for preparing epoxy fiber composite material for wind turbine blades as described in claim 1, characterized in that, The amine curing agent includes any one of isophorone diamine, triethylene tetramine and 4,4-diamino diphenyl sulfone.

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