Selection of other additives for PVC blown film
selection of other additives for PVC blown film
(1) Chelating agent: chelating agent general is refers to the triphenyl phosphite. It is only used as an auxiliary stabilizer and cannot be used alone. When Ba and Cd soap stabilization systems are used together, the initial color of the product can be improved, and the thermal stability of the product can also be improved. Its weight is 0. 5 parts is more appropriate. When the weight is increased again, there is no synergistic effect on thermal coloring, while its stickiness is easy to bring adverse consequences to the processing process.
(2) Ultraviolet absorbent: agricultural films are often used under sunlight, so it is necessary to add appropriate ultraviolet absorbent. Commonly used UV absorbers UV-9 and UV-24. The test proves that the amount of people added is about 0. At 2 portions, the exposure time of selenium can be extended from three months to about one year (Depending on the specific formula)At the same time, there is no adverse effect on crops.
(3) Fillers, surfactants, foaming agents: the viscosity of the film increases with the increase of plasticizer content. Due to the technological limitation of blown film, it cannot be solved by engraving. In order to improve the viscosity, appropriate fillers are often added to the formula. Fillers include talcum powder, titanium dioxide, calcium carbonate, etc. Talcum powder has little effect on transparency. The addition of filler must consider its fineness. If the fineness does not meet the requirements, it will cause stiffness and cause the blown film to rupture during the blowing process. The proportion of filler should be properly controlled, generally no more than 3 parts, so as not to affect the strength.
surfactants, such as stearic acid monoglyceride, xylitol stearate, etc. , also have the effect of improving viscosity, but the addition amount should not be too much, otherwise there will be precipitation phenomenon.
foaming agent can also be added to produce foam blow molding thin touch, so that the surface of the film is rough and the adhesion is improved, and the film is elastic. However, at this time, attention must be paid to mastering the blow molding process so that the foaming process does not occur in the extruder, but is evenly foamed in the die to obtain the ideal product.
In short, in the formula of blown film, Ba- Cd metal soap is used as a stabilizer, plus a stabilizer system composed of superfluous mixture, epoxy ester and ultraviolet absorber. Its aging resistance is excellent. When designing the formula, the proportion of various additives should be fully considered, not only considering the superior anti-aging performance of the film, but also considering the characteristics of blow molding process, it is necessary to consider that the film has a certain degree of softness and low temperature toughness, and it is also necessary to consider that the film should not be too sticky to avoid affecting the use. Related articles: Formulation Design of PVC blown film