Gas checks are visible fleck‐shaped defects that occur on the surface of poly(vinyl chloride) (PVC) films during industrial calendering. Films containing these surface defects often do not meet minimum product specifications and therefore must be disposed of or recycled, resulting in increased cost and material waste. Currently, gas checks are controlled by keeping film gauge low and through trial‐and‐error modifications of processing parameters by calender operators. In this work, our group developed a series of chemical additives that can be blended with PVC to prevent the formation of gas check defects. We found that a series of poly(caprolactone) (PCL)‐based compounds with diester linkers and alkyl chain cappers were all effective at preventing the formation of gas checks during calendering, with additive concentrations as low as 8 phr producing films with no gas checks. We found that the blends produced with our additives had higher melt viscosities than those produced with additives that do not remove gas checks, suggesting that viscosity plays an important role in preventing gas check defects.

中文翻译：

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防止聚氯乙烯压延过程中形成表面缺陷的添加剂

气体检查是在工业压延过程中出现在聚氯乙烯（PVC）薄膜表面上的可见斑点状缺陷。包含这些表面缺陷的薄膜通常不符合最低产品规格要求，因此必须进行处理或回收，这会导致成本增加和材料浪费。目前，气体检查是通过保持菲林尺低和通过压延机操作人员对试验参数进行反复试验来控制的。在这项工作中，我们小组开发了一系列可与PVC混合的化学添加剂，以防止形成气体检查缺陷。我们发现一系列带有二酯连接基和烷基链封端基的聚己内酯（PCL）基化合物都能有效地防止压延过程中形成气体检查，添加剂浓度低至8 phr的生产薄膜，无气体检查。我们发现，用我们的添加剂生产的共混物的熔体粘度高于不除去气阻的添加剂所产生的共混物的粘度，这表明粘度在防止气阻缺陷方面起着重要的作用。