PVC cable material is a particle prepared by mixing, kneading and extruding polyvinyl chloride as the base resin, adding stabilizers, lubricants and inorganic fillers. Although its intermediate performance is general and not environmentally friendly enough, its price is low and the process is simple; PVC cable material is still one of the most widely used cable materials. When using PVC cable material, there may be pores, rough surface, brittleness, etc. Let's discuss in detail how these phenomena are caused:
one. Cable material air hole problem
There are two main reasons for this problem, one is the problem of moisture, and the other is the problem of degradation.
1. The moisture content of the raw material is high. The raw materials that may have excessive moisture content are PVC resin, plasticizer, filler and stabilizer. Due to the relatively large amount of addition, PVC resin and filler should be the focus of inspection. This situation is generally manifested in the kneading process and the vacuuming of the extruder.
2. The stability of the formula system is poor or the high temperature residence time of the material is too long, and the material is decomposed, resulting in the appearance of pores. When this problem is severe, it is usually accompanied by a color change.
two. Rough surface of cable material
There are two kinds of rough surface, one is pimple and the other is pitting.
1. Pimple phenomenon
Mainly: it is formed in the cable material by some powder aggregates that are not uniformly dispersed during mixing, which cannot be plasticized during the extrusion process.
Fish eyes of PVC resin and PVC resin particles that do not fully absorb plasticizers can also cause pimples, but they are generally small.
Today's formulas pursue finer and more fillers. If the surface of the fillers is not handled well, the mixing effect will be poor, and the probability of agglomeration will be relatively large. Just the size of the agglomeration and whether the performance in the cable material is serious? Has it become a problem?
2. Pock problem
Pockmarks are relatively complicated, and are generally considered to be related to the small molecular substances running out of the material. These small molecular substances come from the resin itself, plasticizers, and lubricants.
Since it is necessary to vacuumize when extruding and granulating to produce cable materials, it is reasonable to extract these small molecular substances, but why do they still appear? Pass
After analysis, it is found that in fact, these small molecular substances are mostly produced in the material after vacuuming, and many of them come from a small amount of lubricants, and of course plasticizers.
three. Poor insulation of PVC cable material
Due to the limitation of PVC material and the influence of additives such as plasticizers, the insulation of PVC cable materials has a certain limit. For ordinary cable materials, if the insulation is obviously deviated, there are mainly the following reasons:
1. Too many impurities
The mixing of impurities will adversely affect the cable material, and excessive impurities will cause insulation problems. These impurities may come from PVC resin and various additives, or from the mixing and feeding process.
2. The powder particles are too coarse
The powder additives in the cable material are generally used after grinding. If it is easy to save trouble or some mechanical failure, the added powdery material particles are too thick, which will adversely affect the insulation of the cable material.
3. The problem of heavy metals in colorants
Many pigments are heavy metal salts. These heavy metal ions will improve the electrical conductivity of the cable material and reduce its insulation. So the choice of cable material pigment is very important.
Four. Cable material damp problem
Because there is a certain proportion of fillers in the cable material, and some also have a certain proportion of low-grade plasticizers (or substitutes for plasticizers), cable materials that are not prone to moisture will also have such problems in certain seasons.
The moisture of the cable material has a lot to do with the packaging process and the packaging. Drying should be strengthened to cool it to a certain temperature and then seal it. In addition, the packaging should be improved and moisture-proof measures should be added.
At the same time, attention should also be paid to the phenomenon of false damping caused by potential degradation and surface coating.
five. Cable material brittle problem
The problem of the brittleness of the cable material is generally related to the formula components such as the type of PVC resin, plasticizers, lubricants, and fillers.
1. Select a high model
If the PVC resin is selected with a high model, the performance of the cable material will be brittle due to the short PVC molecular chain. The amount of plasticizer added is small, and the cable material is hard and sometimes brittle.
2. The amount of filler added is too large
It is more because the amount of filler added is too large, which causes the performance of the cable material to decline and the strength to be poor.
3. Lubricant
Lubricant is another key point. If the external lubrication is too much, it will often cause poor plasticization (low plasticizing temperature is another main reason for poor plasticization). At this time, the cable material will obviously have poor strength and become brittle.
Source: Dongtuo Chemical, Flame Retardant.
For more consultation, please pay attention to: flame retardant, triphenyl phosphate, halogen-free phosphorus flame retardant, polyurethane flame retardant.
