Product Description

Depending on the nature of the elastomer and the condition of the material, the appearance and processability of the material should generally be tested prior to molding. The granules provided usually contain varying degrees of moisture, fluxes and other volatile low molecular weights. In particular, the TPR moisture content with a tendency to absorb moisture always exceeds the limits allowed by the process. Therefore, it is necessary to carry out a drying treatment and measure the water content before the treatment. The water content of TPR at high temperatures needs to be 5% or less, or even 2% to 3%. Therefore, the vacuum oven is usually dried at 75 ° C to 90 ° C for 2 hours. The dried material must be properly sealed and stored to prevent the elastomeric material from absorbing moisture from the air and losing its drying effect. Thus, the drying chamber hopper can continuously provide dry heat to the dryer, which simplifies operation, maintains cleanliness and improves quality. It is advantageous to increase the injection rate. The drying hopper is typically loaded 2.5 times more than the injection molding machine.

SBC-based TPE elastomers are superior in color to most other TPR materials. Therefore, they only need a smaller amount of masterbatch to achieve a certain color effect, and the resulting color is purer than other TPR. Generally, the viscosity of the masterbatch should be lower than the viscosity of the TPR because the melt index of the TPR is higher than the melt index of the masterbatch, which will promote the dispersion process and result in a more uniform color distribution.

For SBS-based TPE elastomers, polystyrene-based vehicles are recommended.

For TPR elastomers based on harder SEBS, polypropylene (PP) carriers are recommended.

For TPR elastomers based on softer SEBS, low density polyethylene or ethylene-vinyl acetate copolymers can be used. For softer varieties, PP vehicles are not recommended as the hardness of the composite will be affected.

For some applications of package injection molding, the use of polyethylene (PE) carriers can adversely affect adhesion to the substrate.