the die is cast how to choose the coating material of pp/pe woven fabric?

by:Hanway     2019-08-21
In the PP and PE extrusion coating process, coating materials need to be stricter than the yarn extrusion process. The choice of raw materials is not good, the fluidity is insufficient, and the peel strength is insufficient.Therefore, the choice of raw materials should pay attention to the following properties: a) good flow performance is required, good fluidity, so that the film thickness of the coating is uniform.Due to the longer die head coating, especially with the die width waterproof oil cloth once coated on both sides of the folding length of the die head and the double head, the material in the mold flows through a relatively long distance, the resistance in the mold is large and there is no selected resin fluidity, which will cause uneven film thickness and large flow rate range. the mold lip temperature is not like this, and there will be some loss of viscous elastic cooling, and the stickiness of the fabric is not strong.The liquidity index is an indicator to measure the melting index M1, in general, polyethylene is 4-15g/10 min, polypropylene is 7-30g/10min.B) the melt that needs to flow out of the mold with a high melting strength has a certain viscosity elasticity, that is, a higher melting strength.Since the distance of the investment die is a weaving traction and stretching process, there is a certain traction ratio, which requires a certain investment die strength to be pulled and not broken.The distance of the die port, due to the inertia weight and traction speed, can the melt fluidity of the die port be very good, in order to avoid uneven vertical thickness of the film or pile, so the melting index of resin cannot be too high.The melt index of polypropylene material used for flat yarn is about 2 ~ 6g/10 minutes, it is not suitable for coating, the flow is too slow, and the thickness is not uniform.C) good thermal stability is required because the coating is carried out under high temperature conditions and the extrusion temperature is usually about 290 higher than that of the yarn extrusion material.
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