According to the above mechanism, the structure of the plasticizer preferably has two parts: polar and non-polar. , the polar part is often composed of polar groups, and the non-polar part is often an alkyl group with a certain length. Commonly used polar groups are energetic groups, chlorine atoms, epoxy groups, etc.. Compounds containing different groups Have different characteristics. For example, phthalic acid has good compatibility, plasticizing effect, and comprehensive performance, and is often used as the main plasticizer.
Phosphate esters and vaporized compounds are flame retardant; epoxy compounds have good heat resistance; aliphatic dibasic acid esters have excellent cold resistance, etc. Of course, in addition to the polar group of environmentally friendly plasticizers, the structure of other parts of the plasticizer molecule also has a great impact on the performance of the plasticizer.
Take vinegar plasticizers as an example. Esters containing aromatic ring structures have better compatibility than aliphatic esters, but their cold resistance is worse than aliphatic esters. The ring family is centered.
If the number of carbon atoms in the alkyl group is 4 or more, the cold resistance gradually increases. The longer the carbon chain of the environmentally friendly plasticizer, the better the cold resistance; but When the number of carbon atoms exceeds 12, the compatibility and plasticizing effect will decrease. The longer the carbon chain, the smaller the volatility and mobility. The plasticity and cold resistance of linear alkyl groups are good. As the alkyl branch increases, the cold resistance becomes worse and the plasticizing effect also decreases.
Ester groupThere is not much difference in the plasticizer performance of the structure. The number of ester groups is usually 2 to 3. Generally, there are more ester groups, and the mixability and transparency are good.
Compared with esters synthesized from primary alcohols, esters synthesized from secondary alcohols have poorer compatibility, plasticizing effect, cold resistance, and heat resistance. .
In addition, plasticizationagentThe size of the molecular weight should be appropriate. If it is too small, the volatility will be high. If it is too large, the plasticizing effect will be reduced and processing difficulties will occur. The molecular weight of better plasticizers is generally between 300 and 500.
