Wind power generation is an encouraged and urgently needed energy conservation and environmental protection project. Wind turbine blades working in the open air have high requirements on bearing strong wind load, sand scouring, ultraviolet radiation, atmospheric oxidation and corrosion, acid salt corrosion, material cost, etc. At present, carbon fiber reinforced epoxy resin composite material has been used for megawatt fan blades. The required epoxy resin has low viscosity, good fiber permeability, high impact resistance and good toughness. The general epoxy resin has high viscosity, poor impact resistance and weather resistance, and the paint film is prone to be powdered and tarnished outdoors, so it is not suitable for outdoor coating and adhesive. It is of great significance to develop new epoxy resin for wind turbine blades. The new bisphenol F epoxy resin has the advantages of low viscosity, strong solvent resistance, high impact resistance, good fiber impregnation and composite performance with glass fiber reinforced plastic, and low use cost, so it is expected to be used to manufacture basic materials for wind turbine blades. The main raw material bisphenol F has been produced abroad, but there are problems such as high phenol formaldehyde ratio, low content of para isomers with performance, low yield, complex post-treatment of products, etc., and large cycle evaporation is applied, and reaction is conducted under heating conditions, resulting in high production costs. However, the price of imported bisphenol F is too high, resulting in few large-scale production of bisphenol F epoxy resin in China. Firstly, bisphenol F was prepared by electrophilic substitution reaction in the presence of phosphoric acid catalyst and methanol solvent, Under this reaction condition, the yield of bisphenol F product is 92.2% (calculated as per mole of bisphenol F available), and the content of 4,4 '- isomer in the obtained bisphenol F product is 73.2%. Then, bisphenol F and epichlorohydrin are etherified in the presence of catalyst tetramethyl, and then solid sodium hydroxide is added for epoxidation dechlorination reaction, and then refined to obtain bisphenol F epoxy resin. The effects of raw material ratio, reaction time and temperature on the chlorine content and epoxy value of the product were studied, and the appropriate process conditions were determined: epichlorohydrin/bisphenol F (mol)=10:1, dichloropropanol/epichlorohydrin=0.2, tetramethyl dosage of 2% (mol/BPF), etherification temperature of 80 ℃, time of 5h, epoxidation catalyst of powdered sodium hydroxide, excess of 2%, closed-loop temperature of 70 ℃, and time of 1.5-2.0h. The bisphenol F epoxy resin prepared under this process condition is light yellow and transparent, with good low-temperature fluidity. The yield is 91%, the epoxy value is 0.57, the organic chlorine is 2.110-4, and the inorganic chlorine is 1.310-4. The product was preliminarily confirmed as bisphenol F epoxy resin by Fourier transform infrared spectroscopy and nuclear magnetic resonance analysis.
Cyclosulfide resin is very similar to epoxy resin in structure, but because of its structural properties, in addition to some advantages of epoxy resin, it can also be cured quickly at low temperature, has good bonding with metal, high refractive index, etc., so it has good applications in the fields of rapid curing at low temperature, substrate bonding, optical resin materials, etc, The study of cyclosulfide/epoxy resin has broad application prospects. During the experiment, the bisphenol F cyclosulfide/epoxy resin system with low viscosity was prepared, which effectively avoided the shortcomings of high viscosity and poor fluidity of the resin system in operation. Two kinds of curing agents, amine and anhydride, were selected to explore the resin/curing agent system in detail. The main work of this paper is as follows: First, bisphenol F ring epoxy resin was prepared with bisphenol F epoxy resin and potassium thiocyanate as the main raw materials. The structure of the synthetic product was characterized by FTIR, 1HNMR, element analysis and other means, and two analytical methods, infrared working curve and nuclear magnetic spectrum, were established to quantitatively analyze the content of cyclic sulfur in the synthetic product. Among them, the epoxy conversion rate of the synthesized product is 67%. Secondly, compared with epoxy resin, cyclosulfide resin has greater ring tension, so it is more active, easier to open the ring and has polymerization reaction.
Main characteristics of epoxy resin mortar:
1. Good thixotropic property: the thixotropic property is excellent, and the material is in a gelatinous state that is not easy to flow when standing. Even if the material is smeared in the grooves and holes on the top or side, it will not produce deformation, sagging and other phenomena, which is easy for construction quality; When subjected to shear forces such as mixing and extrusion, it has good fluidity flow and is easy to operate.
2. Good self leveling property: shrinkage cavity, scratch and other defects generated during construction can self heal during its curing process, which is easy for construction quality.
3. Good bonding performance: the main mechanical properties are excellent, and the bonding with concrete is firm, so it is not easy to crack on the bonding surface.
4. Good compatibility with concrete: it has low elastic modulus and good flexibility, can improve the impact resistance of the curing system, resist deformation caused by external forces, and is not easy to brittle failure.
5. : Material, meeting environmental protection requirements.
Select epoxy resin from the use
It is better to select resin with medium epoxy value (0.25-0.45) as adhesive, high epoxy value (>0.40) as castable, and low epoxy value (<0.25) as coating.
Select epoxy resin from operation requirements
It does not need high temperature resistance and has little requirement for strength. It is hoped that the epoxy resin can dry quickly and is not easy to lose. The resin with lower epoxy value can be selected. If you want good permeability and strength, you can choose the resin with higher epoxy value.
The epoxy resin curing system has polar groups such as epoxy group, hydroxyl group, ether bond, amine bond and ester bond, which endows the adhesive strength of epoxy curing products. It has high bonding strength and other mechanical properties, so it can be used as structural adhesive.
