Illustrate the weldability of PVC film
The welding strength of polyvinyl chloride film shall be measured in the welding performance test. The test shall be carried out on test equipment that can be adjusted and controlled at will. The highest temperature at the weld can be measured with an automatic thermometer. The general situation of welding temperature is as follows:
hard polyvinyl chloride film 150 ~ 170 ℃
soft PVC film 120 ~ 170 ℃
heat sealing film 90 ~ 120 ℃
pull the welded plastic film sample hard by hand, the weld itself should not crack, and the crack must be next to the weld. This is a sign to judge the quality of welds.
cut the weld vertically, and the obtained cross section and Figure 3-Cross-sectional drawings in 49 are compared. Figure 3- The section of 49e is the normal section of high frequency Weld, thus reasonable welding conditions can be determined.
The thickness of the weld seam can only be at most 1/2 of the total thickness of the original two films. The circular flange weld marks on both sides of the weld shall be uniform, symmetrical and free of bubbles.
The symmetry and uniformity of high-frequency welds are closely related to whether the weld strength presents a maximum value.