Polyolefin filling masterbatch is composed of carrier resin, filler and various additives, in which filler accounts for the main component, up to 90%. Polyolefin filling masterbatch is mainly used in the production of polyolefin plastics such as polyethylene and polypropylene. Such as: polyethylene hollow blow molding products, polyethylene injection molding products and polyethylene film, polypropylene woven bag, woven cloth and packing belt, etc. Generally, when selecting the raw and auxiliary materials of olefin filling masterbatch, the good performance and low cost should be considered.
Filling masterbatch filler
The filler used in polyolefin masterbatch is mainly heavy calcium carbonate, followed by talcum powder, kaolin, calcium powder and other inorganic fillers. For any inorganic filler, particle size and particle size distribution are important technical indicators. Generally, the smaller the particle size and the narrower the distribution, the better the filling effect. In addition, the filling effect is also related to the dispersion. The smaller the particle size, the more difficult the dispersion is and the higher the price is. Purity is another important technical index of inorganic filler, the less impurity content, the higher the purity, the better. In general, the content and whiteness of heavy calcium carbonate should be as high as possible, generally more than 94%. Ensure that other indicators meet the requirements, the price should be low, in order to reduce the cost of masterbatch.
Filling masterbatch carrier resin
The performance and cost of polyolefin filling masterbatch mainly depends on the carrier resin. Generally, the content of carrier resin is 10% ~ 20% according to the use of the masterbatch. The carrier resin used in polyolefin filling masterbatch should have good compatibility with the filled plastic matrix resin. From this point of view, the general carrier resin is the best choice of matrix resin. In addition, the melting point and melt fluidity should be considered when selecting the carrier of filling masterbatch. The melting point of carrier resin should not be higher than that of matrix resin. At present, some enterprises still use LDPE (1f7b) as carrier resin, which is mainly due to its low melting point and high melt flow rate (7G / 10min). However, due to the high melting temperature of polypropylene (20 ~ 40 ℃ higher than that of general polyethylene), its use in polyethylene plastics is limited, and the melting point of random polypropylene or powdered polypropylene synthesized by liquid phase bulk method is less than 100 ℃, so it is widely used as carrier of polyolefin filling masterbatch.
LDPE (1f7b) is used as carrier resin for polyolefin filling. Its main advantages are low melting point, high melt flow rate and high melt strength, but the outstanding disadvantage is high price. If low-cost low-density polyethylene resins with low melt flow rate, such as 1i2a-1 or 2f2b, are selected, due to their low melt flow rate, which is generally about 2G / 10min, more additives such as paraffin need to be added during processing to facilitate better dispersion of masterbatch in matrix resin. The main reason is that the properties of carrier resin and matrix resin are the same and the compatibility is good. The master batch for filling polyethylene film has higher and stricter requirements on carrier resin.
Polypropylene is the best carrier resin for filling masterbatch of polypropylene products. In theory, atactic polypropylene is the best because of its low melting point, good melt fluidity and good dispersion. However, according to China's national conditions, it is more appropriate to choose the liquid phase bulk synthesis of powdered polypropylene because of its low price and powdery nature, it is easy to mix with inorganic fillers evenly, and it will not be stratified even in the hopper. Because of the poor thermal stability of polypropylene, antioxidants and lubricants must be added at the same time. In order to make the additives which only account for a few percent of the total resin can be evenly distributed in the resin, it is better to mix the resin with various additives first, and then mix with the filler according to a certain proportion for granulation.
In order to be widely used, polypropylene and polyethylene with similar melt index can be used as carrier resin according to a certain proportion. In this way, some properties can be improved when the masterbatch is used with polyethylene, and the elongation can be improved by mixing with polypropylene.
Recycled polystyrene is widely used in synthetic leather manufacturing process. Even if the compatibility between carrier resin and matrix resin is not good enough, the influence of carrier resin on the properties of plastic products is far less than that of fillers, which can bring considerable economic benefits. In order to improve the processing fluidity and dispersion of the filler masterbatch in the matrix resin, a small amount of recycled polystyrene is often added when other resins are used as carriers.
Because the production cost of the filling masterbatch mainly depends on the carrier resin, and the content of the carrier resin in the masterbatch is less, the performance of the general filled and modified plastic products is not affected. In order to reduce the cost of the masterbatch, waste polyethylene, polypropylene plastics or the leftover materials of polyethylene polypropylene composite film are often used as carriers.
Filler masterbatch additives
The main additives used in polyolefin filling masterbatch are dispersant and surface treatment agent. The effect of dispersant is to improve the processing flowability of masterbatch, which is conducive to more uniform dispersion of masterbatch in matrix resin. The commonly used dispersants are white oil (Liquid Paraffin), paraffin, dioctyl phthalate (BOP), low molecular weight polyethylene (PE wax) and stearic acid. The main properties of common dispersants can be selected according to the performance characteristics of fillers and carrier resins. Surface treatment agents can change the surface activity of inorganic fillers from hydrophilic to lipophilic, which is conducive to mixing with carrier resin, mainly including coupling agent and stearic acid https://www.goodmasterbatch.com/...te-masterbatch-2616.html