In daily life, we use lots of paper products, such as wrap paper and disposable tableware. We may found that almost all the kraft paper’s inner for food packaging looks reflective and has a smooth touch feeling. This is because they are made from PE-coated paper. Suppose we put the disposable tableware in the water and soak it for a while. In that case, we can easily separate a thin PE film out after the paper fibers get soft.
We’ve introduced coated papers before, PE-coated paper in one of them. It is special, not take the clay but PE(Polyethylene) as the coating; according to different uses, it also take PP(Polypropylene) or PET(Polyethylene terephthalate), etc. During processing, the plastic particles will be coated at the origin kraft paper’s surface by a machine after melting to form an only 0.04cm thin film. Due to it is coating in a hot melting way, it combines with the paper hard and is not easy to strip. And the whole process, without any chemical solvent assist, it’s safe and eco-friendly.
Coating plastic on kraft paper can be said a great innovation. This technology gives the paper lots of new characters, which means a lot to industrial manufacture, and the cost is also low.
The original kraft paper will get soft and out of shape when meeting water; use it to make a cup was a joke in the past until the PE-coated paper came. Because of the thin plastic film, liquid can not contact the paper surface directly and influence it. Hence, the low-cost and easy-process paper became the best choice for making disposable tableware.
Besides, use uncoated paper to pack the deli like French fries or fried chicken, the oil often oozes out the paper and greasy the hands. With the PE-coated paper, this situation will never happen.
A heat sealing machine can remelt the film of the PE-coated paper packaging, pressing and gluing it to reach a sealed purpose.
The plastic film attaches to the paper surface, making the paper’s tear-resistance performance improves a lot. Besides, the paper’s stiffness is also enhanced and becomes not easy to winkle.
The kraft paper that only one side got PE-coated. The coated side can not get an excellent printed effect, so most disposable paper food packaging bags only get coated inside. The outside will print the brand LOGO and relative information to get better promotion.
Double-side PE-coated paper is typically used in making disposable food containers, such as paper cups and to-go boxes. The inner film-coated is primary for preventing water from oozing. And the external coated is for avoiding the water in the air from condensing and making the surface get soft and play a hardness improvement and shaping effect.
Like a sandwich, the PE-coated film is in the middle of two kraft papers. It’s less used alone, typically taken as a surface texture. One side can be pattern printed, the other side mounting on other material like corrugated to improve their dampproof performance.
Release liner paper is made from PE-coasted paper with the release agent. It is usually for making label stickers.
As a popular material for making disposable tableware, is PE-coated paper harmful to human health? This is not a problem to worry about. As long as the paper food packaging products are circulating in the market, they must pass the related tests and get certifications like FDA and EU, etc. They are safe while using reasonably.
Then what is the unreasonable operation? To put the food with paper packaging into a microwave oven is a common wrong. Whether a processed paper product can heat by a microwave oven is depend on the coated material. They have different performances on withstanding high temperatures. Once the temperature over too high, and it will release poisonous substances like PFAS. So most plastic-coated paper products are not allowed to heat by a microwave oven.
PE temperature resistance performance is about 70-80℃, PP is about 120℃. In the international standard, they are not suitable for microwave heating. And PET can resist over 220℃, which is one of the coatings that can be heated by microwave, but it cost higher. Big brands like Starbucks and Nestle have their own R&D laboratories, specialty researching the suitable packaging material for their products. Besides, you can also make certain whether it is safe for microwaves from the label on the packages’ bodies.
Whether the PE-coated paper is friendly to the environment is the most common problem for merchants and environmentalists. In many countries, whether a disposable packaging material is biodegradable, compostable, and eco-friendly are essential factors;. They influence the merchants’ operating costs and even may break the relative laws.
Traditionally, PE, PP, and PET-coated paper’s films belong to plastic; they are all non-biodegradable and non-compostable. They’re recyclable but cost a little high.
Fortunately, a new craft solves this problem in recent years. It is PLA-coated paper, aka biodegradable coated paper.
PLA(Polylactic acid) is a new biodegradable, eco-friendly material made from the refined starch of renewable plants (like corn.) The raw starch is converted into glucose first, then to high purity lactic acid, finally compound Polylactic acid by a chemical. It is 100% biodegradable, under a compostable environment, it can be resolve into COz and water by the microorganism. Even though it cost relatively high, it is still popular in the developed countries. Many big brands’ paper food packaging is all made from PLA-coated paper.