ASO Co., Ltd.

“Resin burn” refers to black or dark brown particulate contaminants formed when polyethylene resin is exposed to excessive heat during the film extrusion process, resulting in carbonization.

Unlike ordinary foreign particles such as insect fragments or paper dust, resin burn is caused by the degradation of the resin itself and is fully embedded within the film layers.
 Therefore, it cannot be removed by rubbing with a fingernail.

 Resin burn occurs through the following sequence:

(1)  Molecular chain scission due to excessive heating
 When polyethylene resin is heated above its optimal processing temperature, molecular chains break, resulting in lower molecular weight fragments.

(2)  Promotion of oxidation reactions
 In the presence of oxygen at high temperature, oxidation reactions are accelerated, generating functional groups such as aldehyde and carbonyl groups.

(3)  Dehydrogenation and cyclization reactions
 Simultaneously with chain scission, dehydrogenation occurs, forming unsaturated bonds. These unsaturated bonds react with each other to form cyclic structures.

 Continuous formation of cyclic structures leads to the generation of carbon-rich black residues, known as resin burn.

The occurrence of resin burn is highly dependent on both temperature and residence time:

Once formed, resin burn is difficult to completely remove and represents a critical quality defect that significantly diminishes product value.
 In food and pharmaceutical packaging, the presence of resin burn directly impacts product safety, making preventive measures essential.

A comprehensive approach based on temperature control, residence time management, and equipment maintenance enables stable supply of high-quality, resin burn-free film products.

Resin burn is one of the most significant foreign contaminant issues in polyethylene bag production.
 Understanding the formation mechanism and implementing appropriate countermeasures ensures stable product quality.