A brief description of the synthesis of bisphenol A epoxy resins

1, synthetic principle
Bisphenol A epoxy resin is composed of diphenol-based propane (bisphenol A) and epoxy chloropropane condensed under the action of alkaline catalyst (usually with NaOH)The course of its reaction is different, there is no conclusion, this book does not discussIn general, however, the main reactions during the synthesis process may be as follows:(1) under alkali catalysis, the hydroxyl hydroxyl of BPA reacts with the epoxy-propylene epoxy reaction of epoxy chloropropane, resulting in a compound-open-loop reaction at the end of hydroxyl chloride(2) chlorinated hydroxylreacts react with NaOH, and the epoxy-closed-loop reaction is re-formed(3) the newly generated epoxy-based reaction of bpd-open-loop reaction with bisphenol A(4) end-of-hydroxycompound reacts with epoxy chloropropane to produce end-chlorinated hydroxyl compound-open ring reaction(5) of the chlorinated hydroxyl reacts with NaOH, de-HCl and then produces an epoxy-closed-loop reactionin the case of excess epoxy chloropropane, the above-mentioned open-open-loop-closed-loop reaction, and finally the second-end base is epoxy-based BPA epoxy resinthe above reaction is the main reaction in the condensation processThere may also be undesirable side effects, such as epoxy hydrolysis reactions, cultural reactions, abnormal addition reactions between phenolic hydroxyl and epoxyIf the appropriate reaction conditions (e.gfeeding ratio, NaOH dosage, concentration and feeding method, reaction temperature, feeding order, water content, etc.) can be strictly controlled), the side reaction can be controlled to a minimumIn order to obtain a predetermined relative molecular mass, the end-based epoxy-based line epoxy resin can be obtainedadjust the dosage ratio of bpa A and epoxy chloropropane, epoxy resins with average relative molecular mass can be producedBpa A epoxy resins can be divided into:liquid BPA epoxy resins (low relative molecular mass epoxy resins, soft resins) according to the average relative molecular massThe average relative molecular mass is low, and the average polymerization is n -0 to 1.8At n-0 to l, it is a liquid at room temperature, such as EP0144l-310 (E-51), EP0l451-310 (E-44), EP01551-310 (E-42), etcSemi-solid, softened point 55 degrees C, e.esolid-state bpsorAverage relative molecular mass is highn s 1.8 to 19Medium relative molecular mass epoxy resin sin is given when n is 1.8 to 5The softening point is 55 to 95 degrees CSuch as EP0l661-310 (E-20), EP01617-310 (E-12) etcHigh relative molecular mass epoxy resin sinSoftening point s100CSuch as EP0l68l-410 (E-06), EP0l69l-410 (E-03) etcusually epoxy resinn's n-0 to 19, its relative molecular mass of 6000, is a low polymerIf n 100, it has a high polymer performanceSuch resins are specifically named benzoic resins (phenoxyesin) to distinguish them from general epoxy resins The relative molecular mass of benzene-based resin is large, usually 3 to 40,000, and the epoxy content is very small In fact, it is a thermoplastic polymer, and its final use does not need to be provided by the curing of the epoxy-based However, it contains a large amount of hydroxyl, which can be used as a chemical modification point and cross-linking point For example, it can be reacted with isocyanate or melamine-formaldehyde resin 2, synthesis method
(1) liquid bisphenol A epoxy resin synthesis method is summarized in general two kinds: one-step and two-step method The one-step method can be divided into one-time alkali-adding method and the second-base-alkali method The two-step method can be divided into intermittent and continuous step-by-step process is to shrink bpa A and epoxy chloropropane under NaOH action, i.e open and closed-loop reactions under the same reaction conditions At present, the largest domestic production of E-44 epoxy resin is the use of one-step process synthesis two-step process is bisphenol A and epoxy chloropropane under the action of catalyst (e.g seasonal ammonium salt), the first step is to generate diphenol-based propane chloroollene ether intermediates by adding reaction, and the second step is to carry out a closed-loop reaction under NaOH's presence to produce epoxy resin The advantages of the two-step method are: short reaction time, stable operation, small temperature fluctuation, easy to control, short alkali age, can avoid a large number of hydrolysis of epoxy chloropropane, good and stable product quality, high yield Domestic E-51, E-54 epoxy resin is the use of two-step process synthesis (2) the synthesis method of solid-state BPA epoxy resin can be divided into two main types: one-step and two-step Step-by-step method can be divided into washing method, solvent extraction method and solvent method The two-step method can be divided into onto-the-body polymerization and catalytic polymerization the -step process (known as the Taffy method abroad) is to reduce bpa A and epoxy chloropropane under NaOH action for the manufacture of solid epoxy resins of medium relative molecular mass The domestic production of E-20, E-14, E-12 and other epoxy resins are basically using this method Among them, the washing method is to first dissolve BPA in 10% Of NaOH aqueous solution, at a certain temperature at a time quickly added epoxy chloropropane to make it react, temperature control After the reaction is complete, it is set aside, washed with boiling water more than a dozen times after removing the upper alkali water, and removing the residual alkalis and by-product salts from the resin Then dewater to get the finished product Solvent extraction is basically the same as water washing, except that organic solvent extraction resin is added after the removal of upper alkali water in the post-treatment process Can significantly improve the effect of washing (wash 3 to 4 times can be) Then by washing, filtration, desolvent to get the finished product This method of product impurities less, good transparency of resin, domestic production plants more used Solvent method is the first bisphenol A, epoxy chloropropane and organic solvent into the reactor stirring, heating dissolved Then add NaOH aqueous solution to the water solution at 50 to 75 degrees C to make it react (the catalyst can also be added to the open loop ether, and then the NaOH solution is added for the de-HCl closed-loop reaction) Reach the end of the reaction and then add a large number of organic solvents for extraction, and then by washing, filtration, desolvent to get the finished product The reaction temperature of this method is easy to control, the finished resin is transparent, the impurities are less, and the yield is high The key is the choice of solvent two-step method (foreignly known as the mment method) process is the low relative molecular mass liquid E-type epoxy resin and bisphenol A heating dissolved, in high temperature or catalyst action to add the reaction, constantly expand the chain, and finally form a high relative molecular mass of solid epoxy resin, such as E-10, E-06, E-03, etc are synthesized by this method There are two methods in the two-step process The ontomatic polymerization method is the liquid bisphenol A epoxy resin and bisphenol A in the reactor first heated dissolved, and then at 200 degrees C high temperature reaction 2h can be obtained products This method reacts at high temperatures, so there are many side reactions, and there is a branch chain structure in the generating material Not only is the epoxy value low, but also the solubility is very poor, and even the reaction will coagulate the pot The catalytic polymerization method is to heat liquid bisphenol A epoxy resin and bps A in the reactor to 80 to 120 degrees C to dissolve it, and then add a catalyst to make it react, so that it heats up naturally Heat ingress cold to 150 to 170 degrees C reaction 1 5h, the finished product is finished by filtration one-step synthesis, the reaction is performed in a lotion in water In the preparation of high relative molecular mass resin, post-treatment is more difficult The resulting resin has a wide distribution relative to the molecular mass and high organochlorine content Products with high epoxy value and high softening points are not easily available to meet the requirements of powder coatings When the two-step synthesis, the reaction is homogeneous, the chain growth reaction is more stable, so the resulting resin relative molecular mass distribution is narrow, the content of organochlorine is low, the epoxy value and softening point can be controlled and regulated by ratio and reaction temperature With simple process, easy to operate, less equipment, short working hours, no three waste, a reaction can be, product quality easy to control and adjust, etc , so more and more attention 3, structural and performance characteristics
in the various applications of epoxy resin, its final use performance is provided by epoxy curings The performance of epoxy curings depends on the molecular structure of the curing The molecular structure and formation of the curing material depend on the structure and performance of epoxy resin, the structure and performance of curing agent, the structure and performance of additives, and the curing process of epoxy resin Here, the structure of bps A epoxy resin on the effect of epoxy resin and its curing properties is introduced (1) the macromolecular structure of bisphenol A epoxy resin has the following characteristics: 1) the two ends of the macromolecule are epoxy-based, which is highly responsive 2) There are many ether bonds in the main chain of molecules, which are a line-type polyether structure 3)n the larger resin molecular chain has a regular, far away from the emergence of many mid-hydroxyls, can be regarded as a long-chain polyol 4) there are also large quantities of benzene, submethyl and isopropyl sylph on the main chain (2) The structural units of bisphenol A epoxy resins give the resin the following functions: epoxy and hydroxyl given resin reactivity, so that the resin curing material has a strong cohesion and adhesion Ether and hydroxyl are polar groups that help to improve leaching and adhesion The ether and C-C bonds make the macromolecules soft The benzene ring gives the polymer heat resistance and rigidity Isopropion also gives a certain degree of rigidity to the macromolecules The C-O-key has a high key energy, which improves resistance to alkalinity Therefore, the molecular structure of bps A epoxy resin determines that its performance has the following characteristics: 1) is thermoplastic resin, but has thermoset properties, can form a variety of curing agents, catalysts and additives with a variety of high-performance curing salutations, almost to meet a variety of use requirements 2) Good process of resin When curing basically does not produce small molecule volatiles, can be low-pressure molding It can be dissolved in a variety of solvents 3) Curing material has a high strength and bonding strength 4) Curing material has high corrosion resistance and electrical properties 5) Curing material has a certain toughness and heat resistance 6) the main disadvantages are: heat resistance and toughness is not high, heat resistance and weather resistance is poor