Table of Contents
Selection of carbon black
Carbon black is the most cheap, high-quality and excellent ultraviolet stabilizer. If carbon black particle size is very small (20 nm), the carbon black concentration is generally set at 2.5%+0.5%. According to the manufacturing method and use of carbon black, the pigment carbon black is generally better used for plastic coloring, and its selection is basically determined by the blackness that the product must achieve.
For the carrier of carbon black masterbatch, linear polyethylene LLDPE with wide applicability is generally selected, mainly in powder form., LLDPE resin as a carrier is conducive to the dispersion and processing of carbon black. It is also suitable for extrusion injection molding and film blowing. After grafting, it is also used for HIPS ABS PP LDPE HDPE, etc. Carbon black masterbatch generally selects the resin with the same melt index as the plastic matrix resin as the carrier, and it is better to select the resin of the same system as the carrier.
Compatibility is the factor that determines the quality of black color masterbatch. If the color master batch is produced from chips or recycled materials, it may contain pollutants or other non-fusible polymers. This will cause some unpredictable and difficult problems, and waste the time and raw materials of the final consumer. At this time, the base resin can be selected to produce high-quality color masterbatch, which has good compatibility during the melting process. High quality color masterbatch can be produced with LLDPE, LDPE, HDPE, PP, PS, SAN, PA and other materials.
Requirements of dispersion degree on equipment
Black color masterbatch is produced with carbon black. Raw carbon black is a very difficult and dirty mixture, which is full of dust, light weight and fluffy. Unless large-scale treatment measures are adopted, it will pollute the machine and workers and make the working environment dirty. Because of this, it is generally selected to complete the pre-dispersion of carbon black on a resin carrier, that is, the black color master batch. The resin carrier is clean, free flowing and easy to use. In addition, in addition to dirt, carbon black has another characteristic that it is difficult to disperse. If the raw carbon black is melted directly during mold injection, the coloring effect will be very poor. The carbon black stripes and spots without dispersion will obviously appear if they are close to the places with less color.
Carbon black, which is difficult to disperse, also puzzles the manufacturers of color masterbatch. The dispersion of black color masterbatch is very poor. When the end user mixes or molds these black masterbatches, its performance is only slightly better than carbon black, but the effect is also unsatisfactory. In order to achieve a stable and high dispersion, it is necessary to use high-level special equipment: internal mixer plus twin-screw water-ring unit. With sufficient dispersion strength, internal mixer plus twin-screw unit can completely mix carbon black and base resin to realize continuous production.