PVC processing additive is acrylate copolymer (ACR). The basic function of PVCprocessing aid is to improve the processing performance of PVC, promote PVC mixture of plastic, in order to obtain good plasticity material at temperatures as low as possible, improve the quality of the products. We focused on the need of different products, processing aids developed the following five types of.
1, general purpose: promote material plasticization.
2, lubrication type: in addition to promote plastic material, has the effect of preventing the adhesion of metal strip, melt and metal surface, prolong the operating period.
3, bright type: in addition to promote plastic material, can significantly increase thesurface brightness of light products, suitable for the surface finish of products require a higher.
4, super plasticizer type: the promotion of ability than other types of plastic material,suitable for material formulation difficult plasticization, such as calcium carbonatecomponent is high, a large amount of lubricant or adding carbon black, fiber andmodified formula.
5, super melt strength type: in addition to promote plastic material, can greatly increase the melt strength of materials, improve production stability, extend the production cycle, improve the mechanical properties, especially suitable for high content of calcium carbonate (more than wt30%) products.
One, improve plasticizing mechanism
No matter what kind of PVC processing form, are required to make PVC mixtureevenly plasticizing, only the uniform plasticizing good material, the product has good appearance and mechanical properties.
But compared with other general plastics, non plasticized PVC only at highertemperature and shear conditions to plasticization, but PVC under high temperatureeasy decomposition, in order to ensure uniform plasticizing, improve the quality ofhard PVC products, should be in the processing temperature as low as possible andas large as possible under the shear stress, the plastic material. In general, PVCprocessing aid must have the following properties, it can promote the plasticizationfunction.
1, the melting temperature is lower than PVC, in the process before PVC melting.
2, because it has good compatibility with PVC, melting in the machining process canincrease PVC particle adhesion, friction, improve the shear torque, generating heat,the temperature distribution of material of uniform, uniform plasticizing degree, so as to promote the PVC material uniform plasticizing.
3, processing aids with molecular sufficiently large amount, in the process ofincreasing the melt viscosity (or intensity), improved melt pressure, to prevent slippingmaterials so as to improve the shearing torque, melt and metal surface friction heatincreases greatly, promoted PVC mixture of the degree of mixing and plasticizing the degree of.
Two, the use of methods
The essence of processing aid ACR as solid plasticizer. If the melting point of ACR,then lower molecular weight down, will eventually become a plasticizer. In the study found, processing aids, low melting point (including plasticizer plasticized melt) speed,good fluidity, but low melt viscosity, low melt strength, melt pressure is low; high melting processing auxiliary plasticizing slower, melt fluidity, but melt viscosity, melt pressure high, the melt high strength, strong ability of late plasticization. The former reduces mechanical properties and durability of PVC material, but the latter almost does not affect the mechanical properties of PVC materials, and to improve theweatherability.
Some processing type ACR good plasticization effect, on a PVC formulation of current and torque greatly improve the extruder, improve the plasticizing degree of PVC, but for another PVC formula may make PVC products become darker in color and color.Sometimes a processing type ACR is suitable for rapid extruder, but at a slow extruderis not necessarily appropriate, and vice versa. Therefore, in order to make a kind ofprocessing type ACR to meet different formulations, different products, different processing equipment requirements is almost impossible. Similarly, the traditionalprocessing aid ACR, not only to meet the fast plastics, but also to meet the processing requirements of melt strength, melt pressure high is impossible. In order to . In order to meet the requirements of individual customers, we developed a series of new with different promote plasticizing properties and different other characteristics ofprocessing aids, to meet the needs of users, the performance of some products can completely replace some imported products, we for the processing aids and the use of the performance are studied in detail, as long as the customer specific requirementsof their own, our new materials research center can recommend the application of theproduct type, dosage and usage to you.
