Process to Obtain an Inexpensive and High Quality Material from Multilayer PET

Background

PET multilayer products include layers with different composition specifications, depending on the needs of the content that has to be protected. This makes mechanical recycling unfeasible due to the incompatibility of these materials. Therefore, post-consumer derived multilayer PET waste cannot be used together with other polymers in the general recycling system, which is mainly oriented to PET and HDPE. Due to this, there is a rejection of15-20% of multilayer material with more than 50% of PET, generating in Europe more than 800,000 tons/year of this waste. At the same time, industrial multilayer PET waste is not being recovered either, going directly to landfill. Moreover, chemical recycling has a low profitability in comparison to mechanical recycling, and it is used for waste disposal, rather than for recovery.

Technology Overview

The methodology developed by Universitat Politècnia de Valencia (UPV) and Technological Institute for children’s children’s products and leisure (AIJU), offers a highly profitable opportunity in the market for plastic materials derived from recycling, by obtaining a material with a great competitive advantage compared to other recycled polyolefins, with a 40% lower cost and with better thermal and mechanical properties, being able to be used in extrusion and injection in toys, automotive, home.

The product is obtained from a base material with more than 50% multilayer PET, also facilitating the reincorporation of this material in the production circuit. Moreover, this waste is currently discarded because it cannot be mechanically recycled. The methodology is designed to facilitate its incorporation in the current recycling plants for postconsumer materials, as well as in the use of industrial waste.

The innovative processing technology presented, allows the recycling of multilayer containers, with a high content of PET in their composition (>50%), not separating their layers by mechanical procedure, but by mixing polymers. It consists of a multilayer PET processing that includes between 50% and 85% of a base material, coming from waste from the integral management of plastic waste container (and not classifiable as PET, HDPE or LDPE), that has been washed and without impurities, in addition to three compatibilizing materials. These added materials are a reactive agent of plant origin, a tackifying agent and a binder matrix, in defined percentages. The complete process consists of cleaning the plastic waste, removing the films and labels, grinding it until obtaining a material with a suitable size for subsequent shaping, extrusion compounding.

The obtained material is a homogeneous product. Moreover, it is achieved by a good mixing of the materials arriving to the form of pellets. Later they can be injected to achieve the desired shape. The material finally obtained is highly competitive with respect to polyolefinic recycled plastics, cheaper and with better physical performance (max. Tensile strength = 26 MPa, 80% deformation at break, Young’s modulus = 970 MPa).

State of development

The technology has been tested in the UPV and in the AIJU laboratories, demonstrating the quality of the materials obtained, both in the processing cost of manufacture and in their thermal and mechanical characteristics. TRL=4.

Benefits

• High profitability in the recovery of multilayer PET.
• Obtaining a uniform material with a high added value. Cheaper (€ 0.4 / kg) and with better thermal and mechanical properties than recycled polyolefins (€ 0.7 / kg), which are highly demanded.
• Obtaining a continuous filament generated by extrusion, easily moldable. Also in the form of pellets.
• Can be used in various plastic forms: sheets, plates, injected, blown parts …
• Complete use in the manufacture of products by injection or mechanical extrusion
• Enables mechanical recycling, avoiding the massive use of chemical recycling.
• The technology makes it possible to formulate and industrialize new compounds with tailored mixtures for customers by plastics recycling and compound sales companies.
• Inclusion of a plant additive, with less environmental impact than those of petrochemical origin.- Includes up to 75% multilayer PET in its manufacturing.

Applications

• Recycling companies: taking advantage of a new source of raw material, by recovering multilayer PET waste.
• Compound sales companies: generation of uniform material with a highly added value and a tailormade composition for their customers.
• Companies that manufacture products by injection or mechanical extrusion: toys, construction, kitchenware, footwear, automotive …
• The Food Packaging sector, by facilitating compliance with the regulations that oblige them to make their packaging recyclable before 2030.

Opportunity

The process is ready for industrial implementation. The development of different industrial prototype products is currently being sought for their validation and subsequent placing on the market. Funding is sought for the development of a pilot plant for industrial validation.