The unsaturated polyester resin and the crosslinking monomer also undergo slow polymerization in the absence of any initiator, thus rendering the resin unusable. Like a monomer such as styrene, some anti-polymerization agents or retarders are often added to the unsaturated polyester resin to prevent the polymerization of the resin during storage and transportation, and have certain stability. Generally, 0.01% to 0.05% of a polymerization inhibitor is added to the synthesis of the resin. Extend the storage period of the molding compound by one week or even two months.
The polymerization inhibitor is a substance which reacts with chain radicals to form a non-radical substance or can no longer be initiated, and the polymerization rate is reduced to zero. A distinct feature is the generation of an induction period. The retarder is a substance which reacts with a radical to lower the polymerization rate and the degree of polymerization. The effects of the polymerization inhibitor and the retarder are only different in degree, and there is no qualitative difference. There are many substances that have both cation polymerization and retardation. For example, nitrosotoluene produces an induction period, and after the induction period, the polymerization rate is lowered. The polymerization inhibitor and retarder are as important in the unsaturated polyester resin as the initiator.
In fact, the stability of unsaturated polyester resins can be classified into three types.
Stabilization of the polymerization process is used to prevent unwanted products, cross-linking, discoloration or other side reactions during or during the polymerization.
The stability of the resin product acts as a polymerization inhibitor at low temperatures, but at a certain molding temperature, the polymerization inhibition can be removed, and the resin is rapidly cured, which requires a certain storage period of the polyester resin.
Stabilization of resin curing Under the action of initiator, accelerator and polymerization inhibitor, although the resin can obtain the parameters such as gel time and exothermic peak time, it is inevitable that the parameter will drift with the extension of the standing time. A specific stabilizer required to prevent this change in gel properties.
QuanZhou Neweco High Polymer Material Co.,Ltd.
Neweco is one of the leading unsaturated polyester resin manufacturers and suppliers,widely used in automobiles, ships, rail transit, wind power generation, pipe cans, heat and corrosion protection, building materials, stone repair, sanitary ware, artificial stone and other industries. Suitable for hand lay-up, spray, pultrusion, winding, molding, vacuum introduction / RTM, casting and other molding processes. Neweco Resin is committed to excellence and focuses on the application of composite materials to provide customers with comprehensive solutions.