Modification of Epoxy Resin
Aug 29, 2023
By reacting phenyltrialkoxysilane with β- The hydrolysis polycondensation reaction of 3,4-epoxycyclohexyethyltrimethoxysilane (A186), or the hydrosilylation addition reaction of semi enclosed cage type tris (dimethylhydrosilyl) heptadimethylsilsesquioxane T7 3H with allyl glycidyl ether (AGE), etc., respectively, produced cage or semi enclosed cage type POSS (referred to as EP-POSS) with three epoxy groups in two structures, which were used for the modification of epoxy resins such as E51, Under the action of curing agent diaminodiphenylmethane (DDM) or dicyandiamide, not only can EPPOSS hybrid epoxy resin coating be cured, but the surface hydrophobicity of the resulting hybrid coating is enhanced, the water contact angle is increased, and the tensile strength, elongation at break, impact strength, and heat stability of the coating are also significantly improved; Based on this, the modified coating can be modified with cyclotetrasiloxane oligomers containing long-chain fluoroalkyl/trialkoxysilyl ethyl groups, which can further improve the hydrophobic effect of the coating surface and increase the water contact angle of the epoxy coating surface from 78 ° to 106 °~120 °.
A nucleophilic substitution reaction between chloromethyl cage silsesquioxane (CMPOSS) and ethylenediamine was used to prepare silsesquioxane (POSS-NH2) with multiple amino groups in its structure. Then, an amino POSS hybrid epoxy coating was prepared by combining POSS-NH2 with epoxy resin (E-51)/diaminodiphenyl sulfone (DDS). It has been experimentally proven that POSS-NH2 can crosslink with epoxy resin, and its curing activation energy is higher than that of the reference epoxy resin. Therefore, as the content of POSS-NH2 in the epoxy resin coating increases, the thermal decomposition temperature of the hybrid resin coating increases, and the heat resistance improves.
The epoxy/phenyl POSS derivatives synthesized by chemical reactions, namely single fold half siloxane (single fold DDSQ) and poly double fold half siloxane (poly DDSQ), were used together with diaminodiphenylsulfone (DDS) to prepare hybrid epoxy resin coatings. The results showed that the toughening effect of double layer poly double fold half siloxane DDSQs on modified thermosetting epoxy resin was significant, while poly DDSQ had good thermal resistance performance, which can endow epoxy resin with better thermal stability, In addition, the phenyl siloxane chains in DDSQ can transform the surface of epoxy materials from hydrophilicity to hydrophobicity.
Cage like γ- Aminopropyl polysilsesquioxane (POSS-NH2) reacted with diluents n-butylglycidyl ester (nBGE) and 1,4-butanediol diglycidyl ester (BDGE) to produce POSS-NH2 hybrid inorganic organic hybrid material. Then, the hybrid material was filled into epoxy resin (E51) to prepare a modified epoxy resin composite coating. The results indicate that the nanoscale effect of cage shaped POSS and the anchoring effect between hybrid POSS-NH2 and epoxy resin can significantly improve the toughness and thermal properties of cured epoxy resin coatings. Based on similar principles, Yang Zhiyou et al. [47] γ- The synergistic use of amino hexahedral oligomeric silsesquioxane and low branched polyester liquid crystal polymer (LLCP) for the modification of epoxy resin resulted in a composite coating with good toughness and heat resistance.
Other modifications
Under the action of stannous octanoate catalyst, the first step is to α,ω- Polycondensation of poly (3,3,3-trifluoropropyl) siloxane (PTFPMS) terminated with disiloxy groups and 2,3-epoxypropropyltrimethoxysilane (KH-560) involves the condensation reaction between Si OCH3 in the KH-560 structure and Si OH at the end of PTFPMS, resulting in the end groups of PTFPMS having strong reactivity and adhesion to epoxy groups. Then, the epoxy modified polysiloxane is compounded with epoxy resin and cured with organic amines, Not only did the fluorinated organosilicon segments be successfully introduced into the epoxy resin system, but due to the flexibility of the PTFPMS segments, the impact strength of the fluorinated silicone modified epoxy resin was significantly improved, and the bending strength and hardness were correspondingly reduced, with a slight decrease in Tg. However, researchers have also found that if the introduction amount of PTFPMS segments in the epoxy system is too high, its hydrophobicity will inevitably lead to poor compatibility between PTFPMS and epoxy resin, and a decrease in impact strength.
GNP-NS loaded polydimethylsiloxane (PDMS) epoxy resin nanocomposites were synthesized using a solvent-free method. The introduction of PDMS modified epoxy resin, improving its hydrophobicity, and increasing its contact angle from 50 ° to 110 °. Moreover, the prepared epoxy resin nanocomposite material coating has better protective performance than pure epoxy resin coating, with significant improvements in wear resistance, tensile performance, anti-corrosion performance, mechanical strength, and hydrophobicity.
By combining diphenylsilanediol with γ- The condensation reaction of aminopropyltriethoxysilane first produces a silicone resin containing amino/phenyl groups in the structure, and then uses it as a reinforcing and reactive curing component to modify and cure epoxy resin in combination with organic amines. The results showed that epoxy resin modified with amino/phenyl silicone resin had higher thermal decomposition resistance, and the introduction of diphenylsiloxane structure in the epoxy resin could endow the modified epoxy resin with higher Tg and effectively improve the mechanical properties of the cured coating; In addition, the organic combination of flexible - (ph2SiO) n - and high bond energy Si-O bonds can also improve the toughness, tensile modulus, and tensile strength of the cured product.
The 3,4-epoxy epoxy ethyl silane (ECTS) and diphenylsilanediol (DPSD) were first condensed into epoxy phenyl oligomer (CAEO) by sol gel method, and then blended with alicyclic epoxy resin and steric hindered phenol to form a UV curing system. Under the action of cationic photoinitiator, not only the rapid curing of epoxy silicone hybrid epoxy resin coating at room temperature can be achieved, but also the coating has good light transmittance and high heat resistance, It has a wide range of potential applications in LED encapsulation adhesives and electronic component packaging.
In recent years, the research progress of organic silicon modified epoxy resin has been achieved through physical or chemical methods, which can significantly improve the heat resistance, flexibility, weather resistance, and mechanical properties of epoxy resin. Among them, phenyl containing polysiloxane or silicone resin and bisphenol A type epoxy resin are modified based on the principle of "similar solubility", and the modification effect of epoxy resin is good. In addition, introducing functionalized nanoparticles such as nano SiO2/TiO2, nano silver, etc. into the epoxy resin system can effectively improve the water and oil repellency, corrosion resistance, and other properties of the epoxy resin.
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