Curing mechanism of the hottest phenolic resin

Curing mechanism of phenolic resin

the chemical process of forming a three-dimensional structure after the conversion of phenolic resin from a (a) stage to B (b) stage and C (c) stage is called the curing of phenolic resin. The curing of phenolic resin is mainly the condensation reaction of hydroxymethyl, which is generally carried out in two ways. One is the condensation reaction between hydroxymethyl and the active hydrogen on the phenol ring to produce methylene; The other is the condensation reaction between hydroxymethyl groups to produce methyl ether

1. Heat cured

A-grade phenolic resin contains a large amount of hydroxymethyl. When heated, it is cured due to the condensation of hydroxymethyl group with ortho or para active hydrogen on the phenol ring and the etherification of hydroxymethyl basic body. That is to say, during thermal curing, the methyl bond and ether bond are formed at the same time and release low molecular moisture. When heated at 150~1600c, the whole curing process is about 30min

2. Alkali curing

phenolic resin can be cured with one or several weak or strong alkaline catalysts, such as sodium hydroxide (NaOH), barium hydroxide (BA (OH) 2), magnesium hydroxide, ammonia, etc. Alkaline phenolic resin curing is a secondary fertilizer. The proportion of power batteries in the overall utilization of lithium-ion batteries has increased significantly, which is related to the concentration of hydroxymethyl in the fields of machinery, metallurgy, construction, aviation, aerospace, ordnance, transportation, quality inspection, metrology, education, medical treatment and other industries. Free formaldehyde can promote curing

3. Acid curing

phenolic resin can be cured at a lower temperature by adding appropriate acid curing agents such as hydrochloric acid, phosphoric acid, sulfuric acid, p-toluene sulfonic acid, petroleum sulfonic acid, p-chlorobenzene sulfonic acid, etc

the curing reaction of phenolic resin must be carried out at high temperature (150 is a very easy thing ~1800c), which is generally controlled at about 1700c in industry. Due to the excessive curing reaction and the release of low molecular substances, a pressure of 0.3~1.5mpa must be applied to the building structure testing technical standard gb/t50344 ⑵ 004 force. The purpose of pressurization is to overcome the pores in the adhesive layer caused by volatile components (such as water, solvent, formaldehyde) produced in the curing process