Editorial Feature

Vinyl (Poly Vinyl Chloride) in Automotive Applications

Aug 5 2021

Vinyl plays a critical role in helping make modern automobiles safe, cost effective and of high quality, while also reducing their impact on the environment.

Image Credit: hedgehog94/Shutterstock.com

Properties and Benefits

Vinyl is used in many automotive applications because the material is so flexible. Vinyl helps:

Makes Cars Last Longer

The average service life of a modern road vehicle is now 17 years in contrast to 11 ½ years in the 1970s. PVC has made a special contribution to this as the principal protector of the underbody (in the form of a wear-resistant coating), as sealants against humidity and in other protective profiles. The durability of PVC has also made it a first choice for the cladding of interior parts such as dashboards and door panels. Longer lasting cars also mean a saving of natural resources.

Conserves Fossil Fuels

PVC itself is a material with a comparatively low energy consumption thereby cutting down the depletion of natural resources. In vehicles, this is enhanced further by the lightness of PVC components in comparison to traditional materials, therefore reducing weight and thus fuel consumption.

Reduces Noise for Car Occupants

The sound-dampening properties of PVC in carpet backings, coatings and linings cuts down the noise for the driver and passengers, increasing comfort and reducing stress.

Makes Cars More Affordable

PVC compounds used in vehicles offer excellent cost-performance advantages. As a result, they bring more quality vehicles into the price range of a greater number of people.

Helps Save Lives

PVC is important in shock-absorbing car components such as 'soft' dashboards, reducing injury in the case of impact.

Increases Design Freedom.

This freedom given by PVC in car interiors allows for even the most challenging designs to enhance the comfort of car interiors. PVC can be made to give many attractive qualities of appearance and leather-like softness.

The Economic Perspective

Now More Widely Used In Vehicles Than Ever

Thanks to its material, technical and cost advantages, PVC has always been a popular material in car manufacture. Today in Western Europe, each new car contains approximately 18 kg of compounded or final product PVC. Taking into account basic PVC prices, processing costs and the volume of car sales, this represents some 800 million ECU annually for Western Europe. For the whole world - of which the Western European market represents 35 per cent - the total value of PVC components is almost 2.5 billion ECU.

Consequences of Restrictions

If restrictions were to be introduced in Europe, and bearing in mind the global nature of the automotive industry, most of the world PVC market would be put in jeopardy. Aside from delivering no real advantages to the environment, such a restriction would have further major economic consequences such as:

Needless Cost Increases From Substitution

The high quality and product advantages of PVC in today's cars are the result of decades of intensive research and development work. Substitution by other materials would require additional research without proven technical benefits and at a higher cost. For example, according to a recent study in the United States - where the automotive market is comparable to that in the European Union - PVC substitution by other materials would cost approximately 1.15 billion ECU annually. The cost of parts would increase by 15 per cent to 100 per cent. Some major European car manufacturers have estimated that the sales price of their passenger cars would increase by between 250 to 500 ECU.

Burden on Component Manufacturers

Just as seriously, the technical difficulties of the transition to alternative materials would fall most heavily on component manufacturers - for the most part, Small and Medium Sized Enterprises (SMEs). The cost of investment incurred in substitution might well drive many such firms out of business or encourage them to relocate to other parts of the world, leading to loss of investment and increased unemployment in Europe. It is estimated that there are several thousand SMEs active in the automotive sector in Europe, employing thousands of workers.

The Environmental Perspective

As a material, PVC has many advantages in environmental terms. It consumes comparatively low energy and resources in production as well as in conversion to finished products. As with all other thermoplastics, PVC can be recycled at end-of-life, after sorting into a single material stream. If disposed of by energy recovery systems with other Municipal Solid Waste (MSW), the heat value of PVC, while lower than that of other plastics, is similar to wood, paper or cardboard or lignite.

With regard to potential atmospheric pollution, concerns have been raised about the chlorine content of PVC during combustion. However:

The presence of PVC makes absolutely no difference to the need to purify incinerator exhaust gases. This has to be done in any case to remove, for example, the nitrogen and sulphur oxides that arise from other materials commonly present in MSW.
PVC is by no means the only chlorine-containing substance in MSW and all such substances liberate hydrochloric acid (HCl) during incineration.
PVC's contribution to HCl formation in MSW incinerators is estimated at 38-50 per cent. The rest comes from household and garden refuse, wood, paper etc.
According to the scrubbing process used, varying amounts of chloride salts are generated. These are the residues created in extracting the HCl from the incinerator exhaust. If a dry or semi-dry scrubbing process is used, I kg of pure PVC will produce approximately 1 kg of salts. These salts are contaminated with hazardous substances such as heavy metals originating from all different kinds of waste products - by no means just PVC - and have to be disposed of under controlled conditions.

Dioxins

Concerns have also been expressed in the media and by certain groups about 'dioxins'. Dioxins are in reality a family of substances, some of which are thought to be harmless, while others are thought to be carcinogens and possibly to pose other health-related problems. They can arise when chlorine-containing substances (e.g.: paper, wood, salt-containing household waste, etc.) are burned in uncontrolled conditions. A modern, well-run incinerator is able to meet the stringent dioxin emission levels set by the European Union without difficulty. Many studies all over the world have also concluded that the presence or absence of PVC in the waste stream has no effect on dioxin emissions.

Costs of Waste Combustion

PVC has no impact on the basic cost of building an incinerator. Such costs, known in the incinerator industry as 'capital costs' would be incurred irrespective of PVC. PVC does, however, affect plant operating costs (also known as 'variable costs'), although this depends on the technology used in the individual incinerator. At all events, such operating costs attributable to PVC are estimated to be between I per cent and 2 per cent of total operating costs.

Accidental Fires

The official report after the tragic fire at Düsseldorf airport in April 1996 showed conclusively that PVC was not responsible for any of the deaths. In accidental fires, any chlorine-containing organic material may give rise to dioxins and HCl, but the primary danger to human life is carbon monoxide and certain polynuclear aromatic hydrocarbons (PAHs), to which all organic substances contribute.

PVC Waste Management

To promote both maximum environmental and economic benefits from plastics, the West European plastics industry supports an integrated approach to waste management for all plastic products. This means choosing the best, most appropriate mix of waste options, with the overall aim of preventing, as far as possible, plastics products from going to landfill at the end-of-life.

These options are:

Mechanical recycling
Feedstock recycling
Energy recovery

This approach is fully supported by the PVC industry of Europe, which has also developed its own policy based on these principles. This is the 'ECVM Policy On PVC Waste Management'.

PVC, like other plastics, is fundamentally recyclable, but there are conditions that have to be achieved to make this technically and economically feasible. Where mechanical recycling is not viable, there are further options of feedstock recycling, energy recovery and, finally, landfill. The appropriate option, in relation to ELVs, is closely linked to the characteristics of the component itself, particularly in terms of size and complexity.

At end-of-life, automotive waste may be broadly categorized into:

Individual (mostly larger) components
Automotive shredder residues

The following sections consider waste management of PVC automotive parts in greater detail, within the waste management themes which apply to all plastics.

Mechanical Recycling

Mechanical recycling of plastics is the reprocessing of used products into new ones. An important requirement, however, for successful mechanical recycling is a waste stream of sorted materials of the same types and to have these in sufficient quantities to be commercially viable.

Mechanical recycling of PVC parts in ELV is no different in principle to that of any other PVC products. Industrial-scale schemes already exist in several European countries for PVC bottles, pipes, window profiles, flooring and roofing membranes.

For PVC, as for all plastic vehicle parts, it is important that the components can be economically retrieved when the vehicle is dismantled. Furthermore, product designs - which aim to achieve passenger safety and comfort - typically combine many different materials. For example, dashboards are often made of a soft PVC skin and a rigid plastic insert; car underbodies are steel coated with PVC; cable harnesses are copper sheathed with PVC. These are difficult mechanically to recycle because of the combination of materials. Despite this, several schemes exist such as 'Wietek GmbH' in Germany for cable harnesses or are being set up such as 'Autovinyl' in France for dashboards and interior trimmings. Research into cable recycling is also in progress at Kema in the Netherlands.

Automotive Shredder Residue - Options for Recovery

At end-of-life, after dismantling larger parts suitable for mechanical recycling, the remainder of the vehicle is shredded. After removal of the ferrous metal fraction (about 75 per cent of total vehicle weight), the remaining residue is known as Automotive Shredder Residue or 'ASR'.

ASR is a mixture of many different materials including, for example, different plastics, rubber, glass, non-ferrous metals, textiles and paints and is therefore not suitable for mechanical recycling. The amount of pure PVC present in ASR is about 4 per cent.

There are two recovery options for ASR:

Feedstock recycling
Energy recovery

Feedstock Recycling

Feedstock recycling processes break down the fundamental structure of plastics materials to recover the basic chemical components. For polymers, these chemical components are hydrocarbons and, in the case of PVC, hydrochloric acid (HCl) as well.

Feedstock recycling operations for mixed plastic waste from the packaging sector with a small PVC content (2-10 per cent depending on the technology) exist today to provide feedstocks for chemical plants. Mixed plastics from ELV in the form of ASR cannot at present be treated in feedstock recycling plants because of non-plastic substances. Pre-treatment of ASR is therefore necessary to remove the inorganic fraction such as glass, non-ferrous metals, sand etc. The European plastics industry is supporting development in this area.

For wastes originating from the selective dismantling process and which are 'rich' in PVC - such as leathercloth and cable harnesses - ECVM has set up a research project to study a range of technologies available to break down materials by heat (known as 'thermal cracking'). The aim would be to recover HCl as a raw material that could be used to produce new PVC.

Energy Recovery

Energy recovery is the process of recovering the intrinsic energy in polymers (all of which are based on oil), in the form of heat or electricity, for industry and/or homes. Energy from ASR can be recovered through incineration together with household waste in MSW incinerators or as a fuel in cement kilos. Combustion of plastics with MSW or with traditional fuels is known as 'co-combustion'.

Co-Combustion in MSW Incinerators

Modern combustion plants which incinerate normal household waste recover energy as a matter of course. They also have to have sophisticated equipment (known as scrubbers) to prevent contaminants from all sorts of materials from escaping into the atmosphere and meet the stringent emission requirements of the European norm (EC 89360 of 8 June 1989). Studies done in France, the Netherlands, Germany and Switzerland have indicated that within the tested limits of 10-15 percent co-combustion of ASR with MSW in modern incinerators is perfectly acceptable and does not interfere with the combustion process nor the composition of the slag and flue gases. As already demonstrated with MSW, the presence of PVC in ASR has no effect on dioxin emissions.

Co-Combustion in Cement Kilns

More recently, cement kilns in some European countries have started using sorted mixed plastics including PVC and ASR as a substitute for oil and coal. Chlorine levels between 1 per cent and 5 per cent appear tolerable, dependent on the applied technology. The HCl is neutralized within the process and does not contribute to flue gas emissions. Research work is being undertaken to exploit the limitation PVC may impose on some of these processes.

PVC in Landfill

The land disposal of used PVC products is considered by the PVC industry as a last environmental option because generally there is no opportunity to recover resources. Such disposal, however, has always been considered safe, as recently confirmed by the Swedish Environmental Protection Agency. There could be minimal leaching of plasticisers out of PVC products, but the Swedish study confirmed these as readily biodegradable. This means that they do not build up in the environment.

To verify the role of PVC in landfills, the PVC industry is funding a joint research project on the long-term behaviour of PVC products in landfills at the universities of Gothenburg and Linköping (Sweden).