Today, Yankang will share a detailed introduction about multilayer co-extrusion blow molding.
Firstly is “WHAT”
What is multilayer co-extrusion blow molding?
Multilayer co-extrusion blow molding is the technology of making hollow container by blowing molding.
It uses more than two extruders to melt and plasticize the same or different plastics in different extruders.
And then compounding, extruding and forming multi-layer concentric composite parison in the die.
Its basic process principle is the same as the single-layer blow moulding technique. Only the moulding equipment uses several extruders to plasticize a different kind of plastics.
Control the integration and bond quality of plastics layers is the key to the multilayer co-extrusion blow molding technology.
Multilayer co-extrusion blow molding is developed to meet the needs in some industries with some special requirements.
Such as the airtightness and corrosion resistance in pharmaceutical, food, and industry.
The following content will help you understand this technology better.
Multilayer Co-Extrusion Blow Molding Characteristics
Multilayer co-extrusion blow molding hollow products are produced by extruding several different raw materials into hollow products through multi-layer die head.
To achieve the barrier performance of the container to external substances.
Adopt coextrusion blow molding, compound a variety of polymers together. Forming the multi-layer containers.
The advantages can be summarized as follows:
Improve the impermeability
Improve the performance of the products. Such as strength, stiffness, softness, heat resistance, transparency and size stability
Improve the surface performance of products. No stripe, no speckle, no scratch. More smooth, cleaner.
Multilayer Co-Extrusion Blow Molding Material Selection
The development of multilayer co-extrusion blow molding technology and equipment makes it possible to choose the best material combination plan.
And this also realizes the production of ideal performance blow molding products.
According to the production capacity range and performance requirements, this technique supports 3-6 layers of production.
When choosing material, the different layers should choose different materials.
The inner layer and outer layer, choose all-new material, which is of high quality.
Attention here, you should according to your production needs to choose suitable raw material.
Because we’re a water tank blow molding machine manufacture, we usually produce a water tank by our machine to test it. For the water tank, HDPE is a good choice. We also use it. Most of our customers also choose HDPE. Its performance makes the blow molding products more durable.
And the intermediate layer, you can use waste material.
Yankang Blow Molding Machine cooperates with SIEMENS, a world-famous brand.
When we design and produce a blow molding machine, we adopt a complete set of original SIEMENS control systems.
Ensure the stable running of the blow molding machine. It can also monitor and control the whole process and all equipment as well.
Multilayer Co-Extrusion Blow Molding Machine
Multilayer blow molding can choose universal extruder and step-less speed regulation of multipurpose dc motor.
The extruder hopper laryngeal is designed for the curve shape. The feed of barrier layer extruder is preheated by temperature control.
Each extruder should be equipped with a torque monitoring device.
The extruders of co-extrusion are operated in parallel and monitored by stages.
The extruders are jointly started. When a certain extruder’s torque drops or feeding interrupts, the whole extruder can stop and act jointly according to the program; the length of parison can be controlled, depending on flow distribution, and can be adjusted automatically and synchronously.
When the melt temperature and torque of each extruder exceed the parallel operation conditions, and when the internal pressure of the bonding layer and barrier layer exceeds the allowable range, the fault display is used to monitor and regulate them.
The die head structure of multilayer co-extrusion is shown in the figure
Multilayer Co-Extrusion Die Head
Multilayer co-extrusion die head is often designed to patchwork type.
Die head housing consists of several flanged exterior die.
The inner die is assembled by several die cores.
The exterior and interior die pellets are processed accurately, and the runner of the die is polished by chromium plating to reduce the flow resistance of the plastic melt.
The whole machine head is heated by a four-stage adjustable power ceramic heater, which cooperates with the quick start of the machine head and has good heat insulation measures.
Ensure that the die head has the best temperature environment.
The whole machine chooses program logic control or computer control.
The velocity distribution in the opening and closing stages of the die and the moving speed of the blowing foam tube can be controlled by a hydraulic proportional valve and numerical position converter.
Yankang Blow Molding Machine adopts the Multi-Layer Die Head Technology design.
It can produce 1-6 layers blow molding products, up to 10 layers.
It can not only produce common plastic water tanks but also supply the production of plastic pallet, road barrier, double ring drum, IBC tank, and many other customized products.
Under this technology, the production efficiency has increased 5 times than traditional machine, and the recycling and utilization rate of materials has increased 4 times.
Multilayer Co-Extrusion Blow Molding Advantage
- It provides higher quality blow moulding products under the more broad width and linear velocity.
- Fill low-cost material. It can save high-quality resin. Recycling use of raw materials. Save the material cost.
- Improve production efficiency.
- The products under this technology are durable, more stable, the quality is higher.
- Multilayer co-extrusion blow molding products usually have high chemical resistance (oxidation resistance, light aging resistance), harmful substance penetration resistance, odor migration resistance, compression resistance, impact resistance, smooth surface, heat resistance, and surface scratch prevention.
Multilayer Co-Extrusion Blow Molding Application
Food and Beverage
Packaging of tomato sauce, rapeseed oil, jam and milk, orange juice, carbonated beverage, beer, etc.
Multilayer co-extruded bottle products have three layers, five layers, and six layers. There are more plastic bottles with six layers of general materials.
This kind of products usually consists of three-layer combination, four-layer combination, five-layer combination, the six-layer combination of 5-10L barrels, plastic bottles below 1L, etc.
Industrial containers for storing and loading various liquids.
In addition to common water tanks, there are IBC buckets, double-ring buckets, and so on.
Industrial containers usually need to have certain impact resistance, and the characteristics of multi-layer co-extrusion blow molding technology determine that multi-layer blow molding products have a certain impact resistance.
Packaging in medicine and cosmetics
Multilayer co-extrusion blow moulding technology is certainly advanced. But only when it is applied reasonably can its advantages be brought into full play.
When we use this technology, we should ensure the stability of each performance. Operate it in standard steps.
On the basis of the stable development of this technology, the application scope of the equipment should be widened as far as possible.
That’s all, the detailed introduction of multilayer co-extrusion blow molding is ending here.
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