Frequent Problems in the PVC Foam Board Production
In the PVC foam sheet extrusion process, the basic problems encountered can be grouped into four categories: first, the stability; second, the melt strength issues; third, lubrication problem; Fourth dispersion issues. In these four categories of issues, especially the first three categories of issues are mutual restraint, and influence crossly, while it is sometimes difficult to immediately distinguish from the surface phenomena of pvc foam board. Lack of stability will affect the entire board, and the foam board will be yellow with large brittleness. The deficiency of melt strength can lead to huge cell in the foam sheet and long longitudinal section bubble. The most direct way to determine whether the melt strength is insufficient is to press sheet wrapping the roller with your fingers and you can feel elasticity in the excellent melt strength. If it is difficult to bounce after the press, which means the poor melt strength.
Lubricant for the PVC material
We need to ensure good melt strength in the PVC materials, order to obtain uniform products in PVC Celuka Foam Board.The foaming agent is developed to solve this problem of the foamed article, and can effectively improve the quality of the foam pipe. Lubricant is divided into external lubricants and internal lubricants, and outer lubricant is good for releasing, which is beneficial on the surface finish. Inner lubricant is good for plasticization and the melt fluidity and it is difficult to control the thickness of the plate with insufficient inner lubricant, resulting in both sides are thin and the middle plate is thick; while if inner lubricant is too much which is prone to the phenomenon of high confluence core temperature. Poor dispersion will bring the phenomenon of unsmooth plate surface.
The process temperature control of PVC board
The above four problems are the fundamental, basic and deep-seated problem. While relative to the four questions above, the process temperature control will be more intuitive and this is the surface problem. The poor temperature control may give rise to the emergence of the fundamental problems. Improving the processing temperature will reduce the stability of material and the original lubrication balance will be broken, with the general performance of the poor external lubrication, especially the late external lubrication, and it is needed to improve the amount of external lubrication. In addition, the increase in temperature will lead to the decrease of melt strength, increase cell foam sheet, to reduce the number of cell and the sheet is easy to be broken. The raise in the temperature will also reduce the melt strength and the melt viscosity, the viscosity decreases shear dispersing reduced ability, for the screw with poor dispersion, sometimes will be dispersed unevenly.
www.potentech.com Potentech employs well-known professors and technical experts in the plastics industry to form an Expert Committee, professionally to develop and produce: PVC foam boards and sheets, PVC mouldings and Modified Engineering Plastic (granules). Poten Cellular (PTJ series) is the real Cellular PVC foam sheet, Production of Cellular technology.