What is the method of plastic blow molding processing

According to Juxinchang, plastic blow molding processing technology emerged during World War II and began to be used for producing low-density polyethylene small bottles. In the late 1950s, with the birth of high-density polyethylene and the development of blow molding machines, blow molding technology was widely applied. The volume of hollow containers can reach thousands of liters, and some production has adopted computer control.

Plastics suitable for blow molding include polyethylene, polyvinyl chloride, polypropylene, polyester, etc. The resulting hollow containers are widely used as industrial packaging containers. According to the production method of preforms, blow molding can be divided into extrusion blow molding and injection blow molding, with newly developed methods including multi-layer blow molding and stretch blow molding.

Extrusion blow molding is a method of manufacturing hollow thermoplastic parts. The well-known blow molded objects include bottles, barrels, cans, boxes, and all containers for packaging food, beverages, cosmetics, pharmaceuticals, and daily necessities. Large blow molded containers are commonly used for packaging chemical products, lubricants, and bulk materials. Other blow molded products include balls, corrugated tubes, and toys. For the automotive manufacturing industry, fuel tanks, car shock absorbers, seat backrests, center brackets, and armrest and headrest coverings are all blow molded. For the mechanical and furniture manufacturing industry, blow molded parts include shells, door frames, frames, pottery jars, or boxes with an open face.

The most common blow molded extruded plastic material is high-density polyethylene, and most milk bottles are made from this polymer. Other polyolefins are also often processed through blow molding. According to their applications, styrene polymers, polyvinyl chloride, polyester, polyurethane, polycarbonate, and other thermoplastic materials can also be used for blow molding.

Recently, engineering plastics have been widely accepted in the automotive industry. The selection of materials is based on mechanical strength, weather resistance, electrical performance, optical performance, and other properties.

3/4 of blow molded products are manufactured by extrusion blow molding method. Extrusion technology forces materials to pass through a hole or mold to manufacture products.

Polymer blending is defined as a process of upgrading a polymer or polymer system through melt blending. The mixing process ranges from the addition of a single additive to the treatment of multiple additives, polymer alloys, and reactive mixing. The mixed polymer is usually pelletized for further processing. However, the industry is increasingly interested in combining blending with the next process, such as profile extrusion, to avoid reheating the polymer.

People use various types of melt mixing equipment, from roller mills and batch mixers to single screw and twin-screw extruders. Continuous mixing (extruder) is the most commonly used equipment because it can provide plastic blow molded products of consistent quality and reduce operating costs. There are two types of mixing: distributed mixed materials can be evenly distributed in the mixing process without the need for high shear stress. This type of mixture is called extensional mixing or laminar mixing.