The most recommended way to recycle PVC is mechanical recycling. The easiest way is to recycle the material directly at the manufacturing plant where the waste is produced. Such wastes are created, for example, during the start and end of production and mechanical processing of final products or wastes caused by production errors. In such a case, with a little effort, the recycled materials can be carefully selected so as not to lead to pollution. PVC waste after mechanical grinding can be used as an additive to the original material. To recycle PVC, it may be necessary to modify the composition of PVC in order to obtain the specific processing properties and performance required for a new application.
PVC is considered a polymer material with very limited mechanical recycling. This is due to the misconception of its low thermal stability and the production of harmful and dangerous substances, which increases the corrosion of processing equipment. The proper use of thermal stabilizers allows obtaining PVC materials with a long-term and stable shelf life in recycling machines. Makes.
When considering the recycling of PVC, we must consider the fact that in processed PVC mixtures, apart from the above heat stabilizers, a number of other additives are also used. These are external and internal lubricants, flow modifiers, mechanical property modifiers, softeners, and often, a relatively high content of mineral fillers, such as gypsum, talc, and titanium white. Their use enables precise adjustment of the processing and functional properties of the processed PVC mixture.
In some cases, recycling PVC materials can save up to 90% of energy compared to the energy input needed to use raw materials. Therefore, CO2 emissions are reduced.
PVC recycling after production
Waste with a specific composition, which is mainly produced in the processing plant, can be directly reprocessed by the mill. It has been proven that unplasticized PVC can be processed several times without obvious signs of degradation. In addition, the number of times a material can be processed can be significantly increased by mixing recycled materials with virgin materials in amounts greater than 30%.
The waste of companies producing windows made of PVC profiles is a relatively large stream of PVC recycling with stable properties and compositions of this mixture. However, this requires the removal of protective coatings and metal scraps from window joints and PVC or EPDM plastic used as sealants or drains.
In general, the steps of recycling PVC profiles are as follows:
In the first stage, it is a single-stage or multi-stage grinding process, which is sometimes accompanied by the separation of waste materials and dust and washing. In the next step, metal parts are separated from polymer materials by electrostatic separators. The metal parts are subjected to electromagnetic separation where the aluminum is separated from the steel. Then, depending on the quality of the material, the polymer fraction is subjected to a washing process where small amounts of plastic with a density of less than 1 g/cm3 are simultaneously separated using flotation. They are mainly PP and PE, which are used as a protective coating for PVC profiles. The cleaned plastic part is separated into rubber, soft PVC and non-plastic PVC using successive electrostatic separation processes.
PVC recycling after consumption
Another issue is post-consumer waste management. Excellent resistance to weather conditions and the process of experience makes PVC products such as window profiles, building profiles and pipe and cable insulation long lasting. An increase in the waste supply from these products can be expected in the near future, as their 30-40 years of use are coming to an end. Although PVC in these wastes does not degrade significantly and can be a valuable raw material for recycling, there may be obstacles in their management. Over the years of using PVC products, legal regulations have changed that prohibit the use of certain chemical compounds such as additives to polymers. In the case of PVC, lead (Pb)-based stabilizers and some phthalate plasticizers are particularly problematic. Solutions to effectively separate these compounds from recycled PVC are being developed.
Short life products (less than two years) make up only 15% of all PVC products. These are mainly PVC bottles and containers. It is also used to produce labels for packaging made from other polymeric materials, especially PET beverage bottles, packaging for pharmacies and household chemicals made from PP and PE. Mechanical separation of PVC from such a waste stream is not a problem
A relatively high amount of PVC is used in medicine. This is mainly in disposable products. Some of them are considered hazardous materials and need to be incinerated, but many of them are valuable materials that can be reused.
. Recycling of raw materials:
Recycling of raw materials is an alternative to mechanical recycling and post-consumer waste disposal. It is more suitable for an unsorted PVC waste stream for which material recycling is not achievable or uneconomical. Its main purpose is to return the raw materials to the closed circuit and recover the energy in the materials. The chemicals produced in the PVC decomposition process have various uses.