The surface of the pouch warped in the shape of a "lotus leaf"
As the material at the side seal is contracted by the heat of the sealing knife, the surface of the pouch is warped in the shape of "lotus leaf".
The structure of BOPP//PE and BOPP//CPP are easy to cause this phenomenon, especially the matte BOPP//CPP material, because the sealing temperature of CPP is higher than that of PE, and the heat resistance of the matte BOPP surface is not as good as ordinary BOPP, so it is difficult to balance the sealing performance and the flatness of the pouch surface during production. The surface material is PET, ONY or the middle layer is AL, PET structure material, so it is not so easy to shrink under the heat of the sealing knife.
When producing products with BOPP//PE and BOPP//CPP structures, the temperature of the sealing knife and the speed of pouch making should be well controlled, and the flatness of the bag surface can generally meet the quality requirements.
