Multi-layer blow molding process
Multi-layer blow molding is the use of several plastics to make a multi-layer composite Pet Preform in a suitable manner and then formed by a general blow molding process.
Multi-layer blow molding is mainly to meet the higher demand for plastic packaging containers such as barrier properties, flame retardancy, weather resistance, heat insulation, internal and external dichroism, etc. for cosmetics, pharmaceuticals and foods.
For example, a double-layer blow molded bottle with an outer layer of PVC and an inner layer of PE, the outer layer of PVC provides good barrier properties, rigidity, flame retardancy and weather resistance, while the inner layer PE makes the bottle non-toxic to the package. Excellent chemical resistance.
Typical applications for multilayer blow molded articles are the packaging of milk, natural juices, tea, ketchup, carbonated soft drinks (CSD) and beer.
Multi-layer extrusion blow molding refers to the plastic preforms of different kinds of plastics after being plasticized by a plurality of extruders, and then formed into a billet layer which is layered and tightly bonded together by a special machine head, and then fed into a blow mold. A technique for inflating a multi-layer hollow article.
This blow molding technology is developed on the basis of single-layer extrusion blow molding. The molding process is almost the same as that of single-layer extrusion blow molding, except that the molding equipment uses multiple extruders to plasticize different types of plastics. The machine head used should be able to extrude the tubular structure of the multi-layer structure, and the three-layer tube blank extrusion equipment
Injection stretch blow molding process
Stretch blow molding: a blow molding process by biaxially oriented stretching, which is divided into a one-step injection drawing process and a two-step injection drawing process.
One-step method: hot pet preform method
Pet preforms, stretching, and blow molding are done in one machine. Pet preforms are semi-finished products in the production process.
The combination of devices is:
1 consists of an extruder and a blow molding machine;
2 consists of an injection machine and a blow molding machine.
Two-step method: cold pet preform method
After the pet preform is cooled, the cold pet preform is reheated for stretching and blow molding. Including injection of preforms for stretch-blow molding of pet preforms; extrusion of pet preforms by directional stretch blow molding.
There are currently four combinations of stretch blow molding:
1-step extrusion stretch blow molding for processing PVC;
2 two-step extrusion stretch blow molding for processing PVC phase PP;
3 one-step injection stretch blow molding for processing PET and RPVC;
4 two-step injection stretch blow molding for processing PET.
Blow molding materials: PAN, PET, PVC, PP, etc.
01. Injecting pet preforms into a directional stretch blow molding process
The bottomed pet preform is first injection molded and continuously sent to a heating furnace (infrared or electric heating) by a conveyor belt (or a rotating belt), heated to a stretching temperature, and then incorporated into a blow mold by means of a stretching rod. Stretched and then inflated. It is necessary to control the appropriate stretching temperature, and it can be molded by multi-cavity (2-8), and the production capacity can reach 250-2400 per hour (capacity is 340-1800g beverage bottle).
02. Extrusion pet preform blank oriented blow molding process
The plastic is first extruded into a tube and cut into a length to serve as a cold billet. Put it into the heating furnace and heat it to the stretching temperature, then take the heated pet preform from the furnace to the molding table through the conveying device, so that one end of the pet preform forms a bottle neck and a thread, and the pet preform is along the axis. After pulling 1.0-1.3 times, the blow mold was closed for inflation molding.
Another method is to take out the heated pet preform from the furnace, stretch it in the axial direction of the tube in the stretching device, and send it to the blow mold. The mold inflates the stretched pet preform and inflates it. Forming and trimming waste edges. The production capacity of this method can reach 3,000 bottles per hour and the capacity is one liter.
Applications: PET beverage bottles, PP bottles, PC bottles
Choosing a professional China Pet Bottle manufacturer, Jilian Plastic is your good choice. Whether it is in the design, production or follow-up service, you will get the most satisfaction.