Main heat stabilizer

PVC stabilizers mainly include lead salts, fatty acid metal salts, and organic tins.

1. Lead salts include all lead salts except lead soap, most of which contain lead salts of lead monoxide (PbO). Lead salt stabilizers are the most commonly used and most effective stabilizers for PVC, but they are not suitable for transparent products; lead salt stabilizers have gradually withdrawn from the market in recent years due to their greater toxicity.

2. Mostly fatty acid (lauric acid, stearic acid, etc.) metal (barium, cadmium, lead, zinc, calcium, magnesium) salts. Its general formula is (RCOO) nM. In addition to interacting with HCl, its main function is to replace active allyl chloride atoms. The stabilizing effect of metal soaps is general, transparent, toxic or non-toxic. They are rarely used alone, and are generally used in combination, mainly for soft products.

3. The general formula of organotin is RmSnY4-m (R is an alkyl group, and Y is a group connected to Sn through an oxygen atom or a sulfur atom). According to the difference of Y, there are three main types of organotin stabilizers: fatty acid salt type, maleate type and thiolate type. Organotins have good stabilizing effects, are suitable for transparent products, and have non-toxic specifications; but their prices are more expensive.

Auxiliary heat stabilizer

1. Epoxy compound

Epoxy compounds are important auxiliary heat stabilizers for PVC. They can enhance the heat resistance and weather resistance of the main heat stabilizers. They are mainly divided into two categories: plasticized type and resin type.
The plasticizing type is mainly epoxy compounds such as epoxy soybean oil, epoxy linseed oil, epoxy butyl stearate, and octyl ester.
The main resin type is epichlorohydrin bisphenol A epoxy resin.
2. Phosphite compounds

There are many types of phosphite compounds, including trialkyl phosphites, triaryl esters, mixed alkyl aryl esters, trithioalkyls, bisphosphites, and polymerizable phosphites.

3. Organic phosphite compound

Organic phosphites are peroxide decomposers, widely used as auxiliary antioxidants in polyolefins and synthetic rubbers, and as chelating agents in PVC. When used together with a metal stabilizer, it can bind metal ions to prevent the catalytic degradation of metal ions, thereby improving the heat resistance and weather resistance of PVC.

4. Polyol

Polyols can improve the thermal stability of PVC and improve the color. It is currently believed that the addition of polyols can absorb impurity ions and inhibit its catalytic degradation and conductivity. The main varieties are pentaerythritol, xylitol, mannitol, sorbitol and so on.