The main reason is that the dosage of
Stabilizer is not enough or grade is not good, should still have the phenomenon of redness. It's possible that a particularly bad stabilizer was used.
But most of the cases are lubrication imbalance caused by the problem, lubrication is too little, especially the outer slip is too little, too plasticizing caused by pipe discoloration, brittle...
Can add
Titanium Dioxide, see if it can cover, if there is no try to add stabilizer or change, if it is calcium zinc stabilizer should pay more attention to the adjustment of sliding agent.
In addition, lubricants affect plasticization,
Calcium Carbonate is added whitening agent, and so on, there is
PVC Resin, other conditions are the same, with bad PVC will become more yellow, need more stabilizer.
In general, will think of the problem of stabilizer, in fact, in the case of sufficient stability, lubrication is also a very important factor. In addition, if the calcium powder is damp, it will also affect the plasticization.
The stabilizer is usually the first consideration, but the problem can generally be solved by adjusting the lubrication system properly. Eliminate the problem of stabilizer, then focus on sliding agent, dynamic balance. Stabilizers referred to in the industry generally do not contain antioxidants. But calcium zinc stabilizers generally contain antioxidants.
The rutile type has a reddish background, while the anatase type has a bluish background. Rutile is better, but more expensive.
Whether rutile type or anatase type titanium dioxide, in the visible wavelength range (400-700nm), their reflectance of light is very high, so they have a good whiteness. But in less than the visible light range such as 300-400 nm UV wavelength range, the performance of the two different crystal types of titanium dioxide is very different.
For
Rutile Titanium Dioxide (red line) in the UV - A band with strong lethality (350-400nm) it is far lower than the blue
Titanium Dioxide Anatase, in other words, its UV absorption rate is significantly higher than the blue titanium dioxide anatase.
In this case, it is around the film of organic resin to share the UV light is much less, so the service life of these organic matter is also long. This is why the rutile type of titanium self-powder, as we commonly call it, has much better weather resistance than the anatase type. These properties are innate.
In extrusion is the type of titanium dioxide base color affects the color of the product, in the later use, titanium dioxide on ultraviolet absorption of different effects on the weatherability of the product to affect its color. Actually, rutile type titanium white just than sharp titanium type slightly yellow not turn yellow, the problem is stabilizer was more likely, it is possible that the use of the composite stabilizer, the current domestic some manufacturer of composite stabilizer added a large amount of lubricant to reduce cost, reduce the dosage of effective components, stability is slightly less than under the same weight.
The temperature is too high, the compression ratio of the mold is too large, the amount of stabilizer added is not enough, the lubrication system has problems, the stability of the resin itself is not enough, the calcium powder tide, the gap between the screw and the barrel has problems, the shear is too large, there are many reasons, but also according to the actual situation!!
We have done chemical products for over 30years. Our main products include PVC RESIN, CPE , TIO2 ,PE WAX, Paraffin Wax, STABILIZER ETC.
