PIPES AND FITTINGS
Extruded PVC pipes and injection-moulded fittings are products with excellent technical properties that meet the most demanding economic and ecological requirements. The variety of PVC pipe systems derives not only from the multitude of dimensions, shapes and colours available, but also the many production technologies employed. Specific additives and manufacturing techniques applied are different measures to achieve the best end product results for a range of different PVC pipe systems: drinking water pipes, sewer and waste water pipes, foam core pipes, corrugated land drainage pipes, gutters and down-pipes for removal of rain water, conduit and duct pipes for protecting electrical cables.PVC additives allow pipes and fittings of high quality to be made efficiently, imparting to the finished products specific performance characteristics, such as high mechanical stability and longevity. Characteristics of PVC pipes and fittings are: strong and durable (expected life of 100 years), easy to install and maintain, unaffected by corrosion, high resistance against migration, good mechanical properties, recyclable, very low permeability, high chemical resistance and cost efficiency. Beside technical and economical requirements, modern society puts a high value on sustainability. Innovative PVC pipes and fittings have been developed to meet growing requirements and make PVC even more attractive.
PVC has demonstrated its versatility as a raw material for the production of general technical profiles and window profiles in particular and enables a multitude of construction and design possibilities. PVC offers excellent environmentally friendly qualities and inherent structural and design advantages over other materials, such as weather and impact resistance, excellent heat insulation and noise protection, long service life and low maintenance costs. The fact that PVC can be recycled several times over also gives an outstanding ecological balance. Important applications are window profiles and frames, cladding profiles, roller shutters, electrical conduits and roofing systems.
RIGID AND SEMI-RIGID FILMS
Rigid and semi-rigid films are primarily produced by calendering. Flat die extrusion and blown extrusion production technologies are also used. Stabilisers for these applications are designed to allow the production of PVC finished articles with desired quality and meet regulatory and market requests. Apart the heat stability efficiency, stabilisers for films production have balanced characteristics of self lubrication in order to provide positive contribution to fusion and melt flow characteristics with no negative influence on transparency or presence of defects like flow lines. Stabiliser dosage permits to optimise processability of PVC films avoiding sticking or over lubrication phenomenon during production. Applications of PVC films can be divided into two main categories: food or pharmaceutical packaging and technical like furniture. Stabilisers for food packaging should not influence the organoleptic properties of packed food. They must be approved by EU Reg. 10/2011. Stabilisers for technical applications should provide very good heat stability and colour hold as additional thermal stress are applied to PVC films like lamination and embossing. Semi-rigid PVC films are normally used for technical applications like self adhesive films, window lamination films, metal lamination and stationary, flooring.
Flexible PVC is used in a large variety of applications. The plasticiser incorporated in the PVC matrix increases its flexibility to almost any desired level and significantly extends its scope of applications. Many different plasticiser types are used to meet specific end-product requirements. Flexible PVC can be processed with various production technologies like calendering, extrusion, injection moulding and blown extrusion, coating and rotational moulding (plastisol). Normally flexible PVC formulations are processed at lower temperatures compared to rigid and semi-rigid PVC. Type and dosage of PVC stabilisers are selected according to the process technology, working conditions and PVC finished articles. Liquid mixed metals stabilisers are typically used like Ba/Zn, Ca/Zn and Mg/Zn. Solid mixed metals mostly Ca-based are preferred when final application requires low VOC (volatile organic compounds), absence of phenol and solvents. Flexible PVC applications can be divided into two main categories: technical and medical.
WIRE & CABLES
Plasticised PVC has been used to produce cable and wire insulation and sheathing for more than 50 years. PVC is one of the most widely used cable polymers for its excellent insulation and sheathing qualities for cables. The PVC used must possess specific characteristics to match the respective application, which can range from earthing, telecommunications, installation and heating lines, to cable for the electronics and automotive industries. The stabiliser system has a significant influence on the performance and service life of PVC cables. It allows cables and wires of high quality to be made efficiently, imparting to the finished products specific performance characteristics, such as good heat stability, good electrical characteristics, initial colour and colour stability, good mechanical properties, stabiliser dispersion and light stability.
Main applications are flexible hoses, pouches for I.V. solutions, blood bags and surgical gloves. The permitted list of additives is restricted and appropriate stabilisers are available which can yield the maximum benefits in performance in this very specialised area. Stabilisers like Ca/Zn paste (ESBO is the liquid carrier) and solid are normally used. All medical applications have to be approved by the relevant national authorities and very often product by product.
Few examples for a wide range of technical everyday products made from flexible PVC are bath sandals, durable walking shoe soles, “rubber” boots, gardening hoses, car interiors, crash-pads, meat wrap films, refrigerator sealants, life vests, fishing buoys, swimming aids, duct tape and gloves. The applied processing procedures cover injection moulding, extrusion, blowing film, calendering, and many other processes like rotational and dip moulding. The versatility of application of products and processes require a variety of complex stabiliser systems. They need to fulfil the requirements such as transparency, food contact approval, weathering resistance, low-fogging, good compatibility, good printability, good adhesion and long term ageing like UV-resistance.
COATINGS & FLOORING
PVC finished articles are mainly produced via calendering or spread coating (plastisol). In some applications, the combination of PVC with other materials like polyester or glass fibres provide excellent mechanical properties and very good dimentional stability, durability, hygienic properties, stain resistance, weather resistance, heat ageing resistance and aesthetic appearance. Examples of PVC finished articles are: tarpaulins, tents, hospital and gym floors and wall coverings. Specific types of stabilisers are selected for these applications according to production technology and process conditions. Stabilisers should provide good early colour and heat stability, good transparency (in case of clear wear layer), good printability, low VOC (volatile organic compounds), low phenol and low odour. For foamed PVC formulations, special type of stabilisers used are called kickers. Normally they are liquid based on K and Zn carboxylates of solid ZnO. These products work as heat stabilisers and activate decomposition of PVC blowing agent (usually azodicarbonamide) at low temperatures. Wall covering and flooring industries are normally using kickers.