Foaming regulator is a high-molecular polymer formed by multi-stage emulsion polymerization of a variety of acrylic monomers. It has the functions of improving melt elasticity, enhancing melt elongation and increasing melt strength, which is beneficial to encapsulating bubbles and inhibiting bubble merger and rupture.
Polyvinyl chloride resin is a straight-chain molecule, with short molecular chain and low melt strength, and the molecular weight of polyvinyl chloride resin used in the foaming of rigid plastic-wood composite low-foaming products is generally very low, which is insufficient to cover bubbles and gas. Easy to overflow and merge into large bubbles. In the formulation of rigid plastic wood low-foaming products, after adding the foaming regulator, due to the increase in molecular weight, the long molecular chains are entangled and adhered to the PVC molecules to form a network structure, which greatly improves the melt strength of PVC and can Keep the bubbles entering the melt to achieve a uniform honeycomb structure, so that the product cells are small and many, the cell structure is more reasonable, and the low-density foam material is obtained. Since the gas will not overflow from the melt, the surface of the material is smoother, Shiny.
During the foaming process of the material, the gas decomposed by the foaming agent forms bubbles in the melt. Among these bubbles, there is a tendency for small cells to expand to larger cells. The size and number of bubbles are not only related to the amount of foaming agent added, but also to the melt strength of the polymer. When there is no foaming regulator or the addition amount of the foaming regulator is less than 3 parts, the number of bubbles in the melt increases correspondingly with the increase of the foaming amount, and the pressure also increases gradually. When the bubble bursts or multiple small bubbles form a large bubble, the density of the product increases.
As the foaming agent increases, the foaming regulator polyethylene wax should also be added accordingly. In the foaming process, the cell wall can withstand the pressure of the gas in the cell, and it will not be broken due to insufficient strength, so that the product cells are small and many, and the cell structure is more uniform and reasonable, thereby reducing the density of the foam. If too much foaming regulator is used blindly, the strength of the melt will be too high, so that the bubbles in the melt cannot expand, which will not only increase the density of the product, but also cause the melt to be extruded from the die lip, and the discharge speed will be slow. All, there are leucorrhea, bright bands, vertical grooves, and even the thickness of the board surface is uneven and uneven.
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