PPA related knowledge

PPA classification:

There are two main types of fluoropolymers (Fluoropolymers), one is Fluororubber and the other is Fluoroplastics.

Fluororubber

Since the technology of PPA in the domestic market is almost always from the American 3M company in the early days, at that time, the type that 3M mainly introduced was fluororubber. Therefore, the fluororubber type PPA bloomed everywhere in the country.

However, since the fluororubber belongs to the rubber phase, there is a disadvantage that it can only be softened and melted at a high temperature, and in the production process, the substrate such as polyolefin is melted, and therefore, the softened PPA is in a molten state. Dispersion ratio in a substrate such as polyolefin

Poor, the fluorine utilization rate is low. If the PPA is not well dispersed, the softened PPA will agglomerate into a mass. After a long time of aggregation, it will be easily precipitated from the die and will form a wire drawing or broken wire on the surface of the product. The product produces defective products.

Fluoroplastics

Fluoroplastics are in the plastic phase. Therefore, when used, they melt together with a substrate such as polyolefin. Therefore, the dispersibility of the melted PPA and the melted polyolefin is very good, and the fluorine utilization rate is also improved. high.

Therefore, foreign PPA manufacturers, on some high-end brands, abandoned fluorine rubber and chose fluoroplastics, such as: DuPont's Z200, 3M company's 5911 is a type of fluoroplastic, in addition, the rest of the country The manufacturer's PPA is almost all fluororubber.

Interaction of PPA with other auxiliaries

The chemical properties of PPA itself are very stable and chemically inert (except for strong alkali conditions). In the case of plastic additives, it is basically not related to UV absorbers, antistatic agents, lubricants, etc. effect.

However, when used with the following additives, they have a mutual physical effect:

1: Positive effect with erucamide and some antioxidants (enhanced PPA effect)

2: Negative effects (attenuated PPA effect) with certain anti-caking aids, fillers, and inorganic pigments such as stearates, talc, silica, titania, and the like.

In addition, conventional PPA is basically acidic (pH is about 5-6.5), and some additives, such as: light stabilizer: 944, 622, 770, etc. are basically alkaline, therefore, If PPA is used with light stabilizers or other alkaline auxiliaries, PPA will destroy the activity of light stabilizers and other auxiliaries.

In the past, customers generally knew that certain flame retardants (acidic) were used together with light stabilizers. Flame retardants would destroy the activity of light stabilizers (acid-base neutralization), so customers basically avoided both. Since the amount of the flame retardant added is relatively large during use, the damage to the light stabilizer is obvious, and it can be found in a short period of time. Therefore, it can attract everyone's attention, and everyone can avoid both at the same time.

However, the amount of PPA added is relatively small. Relatively speaking, the destructiveness to light stabilizers is gradually emerging. It is not easy to find at the time. The longer the time, the greater the damage of PPA to light stabilizers, but in the middle and later stages of use, even It is found that the performance of the light stabilizer is degraded. Because of the inertia thinking, the customer will only find the light stabilizer manufacturer to solve the problem, and will not find the PPA manufacturer. Therefore, the PPA manufacturer will not actively identify such problems.