There will be a partial air layer fabric loss of viscoelasticity

A melt index of polypropylene material used for flat yarn is approx value 2~6g/10min, it is inappropriate for the coating, the flow is too slow, prone to the phenomenon of uneven thickness. As the melt cast into the distance is a woven traction stretching process, there is some traction ratio, it requires a certain degree of melt strength to pull off without being pulled or broken. Thus, the choice of raw materials to pay attention to the performance of the following points:a) Need nice flowing propertiesGood flowability to a uniform film thickness of the coating is uniform. Special coating material, although the scope is small, but highly targeted, can be applied to substrates coated with specific characteristics and access it needs.b) Need high melt strengthMelt flowing out from the die to have a certain viscoelasticity, that is higher melt strength. The distance from the mold woven mouth, because inertia weight and traction speed die due to reasons, the melt flow properties can not be good, in order to avoid uneven vertical thickness of the film or the heap , so the resin melt index can not too high. However, the high temperature causes the polyolefin resin, particularly polypropylene, thermal aging. Divided into two china mattress fabric categories according to the type of raw materials, mainly are PP and PE. Because of the longer die coating, in particular coated on both sides at once folded length of die head, double head, with a die width tarpaulin, the material in the die of the melt flow a longer distance through a relatively long time, resistance in the die is large, a good resin flowability is not selected, it will cause uneven thickness of the film , the flow rate range, the die lip temperature is not such , there will be a partial air layer fabric suppliers loss of viscoelasticity cooling, and braid cloth adhesive is not strong. Such as low temperature coating materials, and anti-aging materials. And thus to choose a good thermal stability of the resin. According to the production process can be divided into homopolymers and copolymers.In PP and PE extrusion coating process,coating material is needed to be more stringent than which of yarn extrusion process, bad choice of raw materials, lack of liquidity and will produce insufficient peel strength. Melting the resin coating material in contact with air during the film, the surface oxidation reaction of a carbonyl group, to increase the adhesion capability. Flowability index is a measure of the melt index M1, generally speaking, the polyethylene is 4-15g/10min, polypropylene is 7-30g/10min. Domestic material coated with homopolymers based. Currently, due to the different coating materials and the second substrate, the coating material on the functional requirements are different, so we had to blend modified based special coating material. In principle, the substrate should be selected PP polypropylene woven material for the coating, the substrate is a woven polyethylene PE coating material should be selected.Types of coating materials market is currently more.c) Need good thermal stabilitySince the coating is carried out under high temperature conditions, the extrusion temperature is typically about 290 higher than yarn extrusion material