Introduction Of Injection Molding Technology For Shoemaking Material TPR

According to the characteristics and feeding conditions of materials, the appearance and process performance of materials should be tested before forming.

The pellets supplied often contain different levels of moisture, flux and other volatile low molecular substances, especially TPR with moisture absorption tendency, which always exceeds the allowable limit of processing.

Therefore, drying must be done before processing and water content is determined.

Under high temperature, the moisture content of TPR is below 5% or even 2% to 3%. Therefore, the vacuum drying chamber is usually dried for 2 hours at 75 to 90 degrees.

The dried materials must be properly sealed and stored to prevent moisture absorption from air and lose the drying effect. Therefore, the drying chamber hopper can provide continuous drying materials for the injection molding machine, which is beneficial to simplify operation, keep clean, improve quality and increase injection rate.

The loading capacity of dry hopper is usually 2.5 times that of injection molding machine.

TPE based on SBC is superior to most other TPR materials in color.

Therefore, they only need a small amount of color masterbatch to achieve a certain color effect, and the color produced is more pure than other TPR.

Generally speaking, the viscosity of Color Masterbatch should be lower than that of TPR. This is because the melting index of TPR is higher than that of Color Masterbatch, which will be conducive to the dispersion process and make the color distribution more uniform.

Polystyrene based color carriers are recommended for TPE based on SBS.

Polypropylene (PP) color carrier is recommended for TPR based on hard SEBS.

For soft SEBS based TPR, low density polyethylene or ethylene vinyl acetate copolymer can be used.

For the softer varieties, PP color carrier is not recommended because the hardness of the composite will be affected.

For some encapsulating agents

The use of polyethylene (PE) color carrier may have an adverse effect on the adhesion to the matrix.

New plastic injection machines need to be cleaned or disassembled if they need to change products, replace raw materials, change colors or find breakage in plastics before they are first used.

Washing machine barrel generally adopts heating cylinder cleaning method.

Plastic materials (or plastic recycling materials) are commonly used for cleaning materials.

For TPR materials, the pition cleaning material can be replaced by the new material.

In the process of injection molding,

Whether the setting is accurate is the key to the appearance and performance of the product.

The temperature setting in the feed area should be very low, so as to avoid clogging of the inlet and let the trapped air escape.

When using color masterbatch, in order to improve the mixing state, the temperature in the pition area should be set above the melting point of the color masterbatch.

The temperature in the nearest area of the injection nozzle should be set close to the required melt temperature.

Therefore, after testing, the temperature range of TPR products in different regions is usually 160 to 210 degrees Celsius and 180 to 230 degrees Celsius.

The mold temperature should be set at high temperature and the condensing temperature in the injection zone, which will avoid the contamination of the mold by water and the streaks on the surface of the product.

The higher mold temperature usually leads to a longer cycle, but it can improve the appearance of welding line and products. Therefore, the range of mold temperature should be designed between 30 and 40 degrees Celsius.