Plastic pollution is a growing concern for our planet, and single-use plastic straws are a major contributor to the problem. As a result, many companies are turning to more sustainable alternatives like PLA (polylactic acid) straws. But how are these straws made? In this article, we’ll explore how an extruder turns PLA into drinking straws.
Before we dive into the extrusion process, let’s first understand what PLA is and why it’s a popular choice for eco-friendly straws. PLA is a bioplastic made from renewable resources like cornstarch or sugarcane. It’s biodegradable, compostable, and has a significantly smaller carbon footprint compared to traditional plastics.
The Extrusion Process
Extrusion is a manufacturing process used to create a wide range of plastic products, including drinking straws. Here’s how the process works for PLA straws:
Step 1. Material Preparation
PLA comes in the form of pellets or granules. Before extrusion, the PLA must be dried to remove any moisture, as this can affect the quality of the final product.
Step 2. Feeding the Extruder
The dried PLA is then fed into the extruder through a hopper into a heated barrel. Inside the extruder barrel, the PLA is heated and mixed with other additives like colorants or reinforcing fibers.
Step 3. Melting the PLA
As the PLA moves through the extruder, it’s heated to a temperature between 180-200°C. This heat causes the PLA to melt and become viscous.
The material of PLA drinking straws is mainly polylactic acid and a part of other ingredients. The proportion of PLA straw raw materials can be different in different straw production factories. So the temperature is not always the same. It depends on the straw materials.
The barrel contains a rotating screw with a helical thread. As the screw rotates, it melts and mix the PLA and other ingredients by applying heat and friction. The molten PLA is then pushed through the barrel towards the extrusion nozzle, where it is forced out of the nozzle’s small opening in a controlled stream.
The rate at which the screw rotates determines the speed of the extrusion process, which in turn controls the flow rate of the molten PLA. The screw’s shape and size also play a role in determining the extrusion process’s characteristics, for example, the uniformity of extruded straw materials.
Overall, the screw in a PLA extruder is a critical component of the extrusion process.
We use our self-developed screw for our straw extrusion machine, which is designed based on the characteristics of PLA material and over 20 years of experience in straw machine production and research. We have obtained various patents for this screw design. The length-to-diameter ratio of this screw is 33:1, which can handle PLA material as well as all types of straw materials on the market and enabling precise control over the extruded material’s properties and ensuring a consistent output.
Step 4. Extrusion
The melted, well-mixed and fully plasticized straw material material will be extruded from a die.
Step 5. Cooling And Solidification
The extruded hot PLA straw will be cooled down and solidified in a water tank.
Step 6. Cutting
The solidified PLA straw will be cutted to a certain length. Usually, common straight straws are completed in this step. But some straws that nedd different shapes will go through the next step: shape forming.
Step 7. Shaping the PLA Drinking Straw
Once the extruded PLA is cut, it’s forced through a die in a straw forming machine to shape it into a certain shape, such as Z-shape straw, flexible straw and spoon shape straw.
To sum up, turing PLA into a PLA straw requires an straw extruder, a cooling tank and a cutter. These three important pieces of equipment are usually called straw extrusion set. For making some special shape PLA straws, a straw shape forming machine is also required.
Marrow, as a professional straw making machine manufacturer & supplier, can offer a full range of straw making machines required by
every stage of straw production. We can provide straw production factories with the best straw making solutions. Contact us right now!
