So far, the unsaturated polyester (resin) matrix used as the matrix of composite materials at home and abroad is basically phthalic acid type (abbreviated as orthophthalic type), isophthalic type (abbreviated as isophthalic type), vinyl ester type resin, etc. .
Orthophthalic unsaturated polyester and isophthalic unsaturated polyester
Phthalic acid and isophthalic acid are isomers of each other. The molecular chains of unsaturated polyester synthesized from them are o-phthalic and isophthalic, respectively. Although their molecular chains are similar in chemical structure, the isophthalic is unsaturated Compared with ortho-phthalic unsaturated polyester, polyester has the following characteristics: ①Isophthalic unsaturated polyester with higher molecular weight can be prepared with isophthalic acid, so that the cured product has better mechanics Performance, toughness, heat resistance and corrosion resistance; ②The purity of isophthalic acid polyester is high, and there are no residual isophthalic acid and low molecular weight isophthalate impurities in the resin; ③Isophthalic acid polyester The ester bond on the ester molecular chain is protected by the steric hindrance effect of isophthalic acid. The ester bond on the phthalic acid polyester molecular chain is more susceptible to attack by water and other corrosive media. Use isophthalic acid polyester The glass fiber reinforced plastic made of resin still has quite high performance after being soaked in saturated sodium chloride solution at 71°C for one year.
Vinyl resin
Vinyl resin, also known as epoxy acrylic resin, is a new type of resin developed in the 1960s, which is characterized by terminal unsaturated double bonds in the polymer.
Vinyl resin has good overall performance: ①Because the unsaturated double bond is located at the end of the polymer molecular chain, the double bond is very active and will not be affected by steric obstacles during curing. It can pass through the The adjacent molecular chains are cross-linked and cured, and it can also be cured with monomer styrene; ②The R group in the resin chain can shield the ester bond and improve the chemical resistance and hydrolysis stability of the ester bond; ③Vinyl resin Among them, the ester bond per unit relative molecular weight is about 35%-50% less than that of ordinary unsaturated polyester, which improves the hydrolytic stability of the resin in acid and alkali solutions; ④The secondary hydroxyl group on the resin chain The wettability and adhesion with glass fiber or other fibers can improve the strength of the composite material; ⑤The epoxy resin main chain, which can impart the toughness of the vinyl resin, and the ether bond in the molecular main chain can make the resin have excellent acid resistance sex.
The variety and performance of vinyl resin vary widely with the different raw materials used. The molecular structure can be designed according to the requirements of composite materials for resin performance.