Plastic processing, also known as plastic molding processing, is a general term for various processes that convert synthetic resins or plastics into plastic products, and is a larger production sector in the plastics industry. With ethylene as the main raw material, propylene, 1-butene, hexene as copolymer, under the action of catalyst, slurry polymerization or gas phase polymerization process, the obtained polymer through flash, separation, drying, granulation and other processes, to obtain uniform particles of the finished product. Including such as sheet extrusion, film extrusion, pipe or profile extrusion, blow molding, injection molding and rotomolding.

Plastic products processing methods:

Extrusion:

Grades used for extrusion production generally have a melt index of less than 1 and a medium to wide MWD. In the process of processing, low MI can obtain the appropriate melt strength. Wider MWD grades are more suitable for extruding because they have higher production rates, lower die pressure and a reduced tendency for melt breakage.

Blow molding:

More than one-third of HDPEDs sold in the United States are for blow molding purposes. These range from bottles for bleach, motor oil, detergent, milk, and distilled water to large refrigerators, automotive fuel tanks, and canisters. The characteristics of blow molding grades, such as melt strength, ES-CR, and toughness, are similar to those used for sheet and thermoforming applications, so similar grades can be used.

Injection molding:

HDPE has countless applications ranging from reusable thin-walled beverage cups to 5-gsl cans, consuming 1/5 of the HDPE produced in China. The general melt index of injection molding grade is 5 ~ 10, and there are lower mobility grades with toughness and higher mobility grades with processability. Uses include daily necessities and food thin-wall packaging; Resilient, durable food and paint cans; And high resistance to environmental stress cracking applications such as small engine fuel tanks and 90-gal waste tanks.

Rotomolding:

The material used in this process is generally crushed into a powder, which is melted and flows in the thermal cycle. Rotomizing uses two classes of PE: general purpose and crosslinked. General purpose grade MDPE/HDPE typically has a density range from 0.935 to 0.945g/CC, with narrow MWD, giving the product high impact and minimal warping, and its melt index range is generally 3— 8. Higher MI grades are generally not suitable because they do not have the impact and environmental stress cracking resistance desired for rotomized products.

High performance rotomolding applications take advantage of the unique properties of their chemically crosslinked grades. These grades have good fluidity in the first phase of the molding cycle and are then cross-linked to form their excellent environmental stress cracking resistance and toughness. Wear resistance and weather resistance. Crosslinkable PE is uniquely suitable for large containers, ranging from 500-gal transport tanks for various chemicals to 20,000-gal agricultural storage.

Film:

PE film processing is generally processed by ordinary blow film processing or flat extrusion processing. Most PE is used for film, universal low density PE(LDPE) or linear low density PE(LLDPE) are available. HDPE film grades are generally used where superior stretchability and excellent impermeability are required. For example, HDPE film is often used in merchandise bags, grocery bags, and food packaging.

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