High-performance fiber material with biopolymer coating

Can coatings of biopolymers (abbreviation for macromolecular polymers) promote the benefits of biodegradable fiber barrier packaging solutions? Can it be applied to mass production? Stora Enso, Walki Wisa, and the University of Technology in Tampere, Finland, collaborated on a four-year SEWALPAP R&D project and eventually developed an advanced, biodegradable, biopolymer-coated coating. Fiber material. This material is suitable for most packaging solutions.

Fiber materials such as paper and cardboard are strong, durable, natural packaging materials that can be used in a variety of cartons, wraps, flexible packaging, and shipping packaging. The moisture resistance and impermeability of paper materials used in food packaging have been greatly improved. Originally, this was achieved by compounding the wax and aluminum foil, but later it provided the necessary protection for the fiber material by using a polyethylene film and a better performing plastic coating.

Today's extrusion-coated paper packaging materials are ideally suited for aseptic and autoclave packaging products with long shelf life. Extrusion coating refers to applying a thin layer of molten plastic film on paper or paperboard, and then applying pressure to stick it.

100% biodegradable

Wood fiber is a renewable natural resource, and 80% to 95% of the raw materials for extrusion coated fiber packaging materials are wood fibers. The remaining 5% to 20% are biopolymers based on recycled raw materials. This extrusion coated fiber packaging material is 100% biodegradable.

In the early 1990s, consumers and industries were becoming increasingly interested in biopolymers. At that time, the UPM Group’s Walki Wisa and Stora Enso had already conducted research and development on this subject, but biopolymers were not widely known. Walki Wisa and Stora Enso have provided packaging materials with biodegradable plastic coatings for the past ten years, and they are always committed to improving their capabilities and developing solutions that meet the needs of customers. In 2000, the two companies joined a cooperative R&D project initiated by TEKES (Finnish National Technology Agency) and the School of Paper Processing at Tampere University of Technology to conduct in-depth research on biopolymers and develop new fiber packaging materials.

The joint project named SEWALPAP includes seven paperboard packaging projects, one of which is dedicated to biopolymers and biodegradable fiber packaging.

Can be mass-produced

Biopolymers consist of renewable raw materials and non-renewable raw materials. In the R&D project, researchers first performed a small-scale test on all biopolymers at the University of Tampere, and then applied the selected biopolymers to an extrusion coating machine for mass production testing.

Researchers conducted various research and testing on various plastics for various needs of packaging manufacturing and terminal use. Tested items include: heat sealability and barrier properties (prevention of penetration by grease, oxygen, steam, odor, etc.). However, some paperboards are tested for their sensory performance. According to current regulations, the project will also study the biodegradability of materials. A single biopolymer may not meet all requirements. Therefore, the researchers will also study multilayered materials containing several biopolymers during testing.

The packaging material with biopolymer coating has the following excellent properties:

● Good thermal resistance ● Good oil resistance and gas barrier ● Good adhesiveness and heat sealability ● Excellent folding performance ● Excellent printability and high gloss can be achieved if required ● Controllable biological properties Degradability ● Can be in direct contact with food ● Low odor absorption of package contents when in direct contact

For some biopolymers, two properties that we must consider are: poor vapor barrier properties, and a small range of coating and packaging processes relative to polyolefins. The requirements for processing biopolymers on extrusion coating lines are very high, but the project offers a lot of processing skills.

The study concluded that packaging materials with a biopolymer coating can be produced in a common paper and cardboard coating process. Companies participating in this research and development project have excellent equipment and can use renewable raw materials to produce biodegradable packaging materials.

Suitable for ice cream packaging

The SEWALPAP project also studied the suitability of biodegradable, biopolymer coated paper and cardboard packaging for ice cream packaging. The researchers compared the biodegradable package with various packages currently in use and tested the material for its vapor permeability, oxygen permeability, sensory properties, and shelf life. The types of packaging studied are: 1-litre cartons, paper cups, spherical balls, and conical packages.

The researchers carried out processing and packing of biodegradable packaging materials in an ordinary production environment and found that the production was very smooth and the printing performance of biopolymers was also very good. A large number of sensory tests showed that biodegradable packaging can completely replace the current paper-based ice cream packaging or aluminum film composite ice cream packaging. Biodegradable packaging successfully passed the entire production process from packaging manufacturing to filling. Studies have shown that the biodegradable materials studied, as well as the slightly modified materials, are very suitable for ice cream packaging.

Market sales

Packaging materials with biopolymer coatings are compostable, which is a contentious issue for their sales. However, the supply and demand for this material do not exactly match. The main reason for this situation is the lack of an integrated biodegradable waste recovery system. The SEWALPAP project investigated other reasons for the low popularity of biopolymer packaging materials. A survey of plastics manufacturers, processors, and supermarket supply chains shows that the following three factors will promote the sales of biodegradable packaging:

● The relevant regulations create favorable conditions for biodegradable packaging.
● The supermarket supply chain believes that converting to biodegradable packaging is profitable.
● Consumers are happy to choose environmentally friendly biodegradable packaging.

Most companies responding to this material want to seek economic benefits from this material transition. Interestingly, this is drawn from a large number of European perspectives. In the UK, the supermarket supply chain is a major contributing factor, and many companies are aware of the economic benefits that the environmental image can bring. Germany’s focus is on creating conditions for the successful sale of biodegradable products through improved waste management practices. The development and smooth operation of waste recycling are also prerequisites for consumers to contribute to sustainable development. The packaging material with biopolymer coating can be composted or recycled as biodegradable waste, so the waste can be saved through garbage sorting. This reduces the impact on the environment.

It is worth mentioning that the current biodegradable packaging materials have the same durability and performance as non-renewable materials. The development of packaging materials with biopolymer coatings has continued to advance and increasingly produces more functional solutions. The paper industry has continued to invest in the research and development of such materials. The SEWALPAP project witnessed huge input from the paper industry in environmental issues and sustainable development. A well-developed, biodegradable, biopolymer-coated fiber material suitable for various packaging solutions has emerged.

(The author is a research expert and a doctor of science from Tampere University of Technology, Finland)
â–  Text / Johanna Lahti
â–  Translation / Chen Ying

Source: "Global Box Industry"