Polycarbonate automotive applications

North America is the largest user of polycarbonate in automotive, accounting for 37% of total consumption in 2002. The share of North America has however been declining since 1999, due mainly to the sharper downturn in US car production after 2000, and the greater market maturity of many polycarbonate automotive applications. The Rest of Asia Pacific is the second largest market with 36%, followed by Western Europe with 18% and Japan with 7%. As in many other polymer classes, the share of China and other Pacific Rim countries is growing fast and is forecast to increase further in future because of the trend for car manufacturers to relocate production to lower cost economies. On the other hand, the shares of North America and Japan have fallen significantly in the last three years. 

The use of ABS has in recent years met considerable competition on two fronts, particularly in automotive applications. For lower cost applications, where demands of finish and heat resistance are not too severe, blends of polypropylene and ethylene-propylene rubbers have found application (see Chapters 11 and 31). On the other hand, where enhanced heat resistance and surface hardness are required in conjunction with excellent impact properties, polycarbonate-ABS alloys (see Section 20.8) have found many applications. These materials have also replaced ABS in a number of electrical fittings and housings for business and domestic applications. Where improved heat distortion temperature and good electrical insulation properties (including tracking resistance) are important, then ABS may be replaced by poly(butylene terephthalate). 

Bisphenol A. One mole of acetone condenses with two moles of phenol to form bisphenol A [80-05-07], which is used mainly in the production of polycarbonate and epoxy resins. Polycarbonates (qv) are high strength plastics used widely in automotive applications and appliances, multilayer containers, and housing applications. Epoxy resins (qv) are used in fiber-reinforced laminates, for encapsulating electronic components, and in advanced composites for aircraft—aerospace and automotive applications. Bisphenol A is also used for the production of corrosion- and chemical-resistant polyester resins, polysulfone resins, polyetherimide resins, and polyarylate resins. 

Polyamide/polycarbonate blends have been evaluated for exterior automotive applications such as bumper beams. Their dimensional stabil-... 

PBT/polycarbonate blend, first introduced in 1980 by General Electric (Xenoy ) has enjoyed a fast growth in automotive applications, particularly for bumpers. The blend was developed to meet the low temperature impact strength, dimensional stability and paintability requirements of rigid bumper fascias [Bertolucci and Delany, 1983], which accounted for the bulk of the current market volume for the PBT/PC blend (estimated 25 kton/y in the USA). The development of commercial PET/PC blends followed shortly after the initial success of PBT/PC blends. Currently there are several commercial blends of both PBT/PC and PET/PC blends available. 

Super-tough poly(sulfone)s can be produced by blending PES with acrylate rubber and a polycarbonate as an impact modifier. From this high impact strength composition, films and molded articles are useful in automotive applications, durable goods and appliances, medical and plumbing applications where resistance to hot, humid environments may be particularly important, and safety equipment and protective gear. 

Acrylonitrile Butadiene Styrene Polymer Polycarbonate Alloy A thermoplastic processed by injection molding and extrusion, with properties similar to ABS. Used in automotive applications. Also called ABS PC alloy. 

Let us first review various thermoplastics used in automotive applications. These include nylon 6,6-based blends (e.g., nylon 6,6-PPO), glass-filled nylon 6,6 with without impact modifiers, homo- and copolymers of PP, polybutylene terephthalate (PBT), polyethylene (PE), bis-phenol A polycarbonate (PC), acrylonitrile-butadiene-styrene (ABS), PC-ABS blends, glass-filled PP, and ABS. 

Silane coupling agents may also be directly used as coatings for a variety of applications (10,13,14). Coupling agents in coatings formulations can be used in either solvent- or water-borne systems, such as clear coats for automotive applications (13,15). Formulations can also be used to impart scratch and abrasion resistance to softer materials such as polycarbonate and poly(methyl methacrylate) (PMMA) (14). Applications of this type allow the use of materials whose bulk properties are desirable because the surface properties can be fine-tuned. 

LCA for the end-of-Ufe was used for seven plastic components that are commonly used in automotive applications. The parts included the bumper cover made from polypropylene (PP), windshield washer fluid container made from polyethylene (PE), air-intake manifold made from 30% glass-filled nylon, air duct made from 20% talk-filled PP, seat cushion made from polyurethane foam, head lamp lenses made from polycarbonate, and mirror housing made from acrylonitrile butadiene styrene (Jenseit et al. 2003). 

In summary, headlight lenses are one of the most common automotive applications for plastics, and polycarbonate was the first commercialized polymer to offer many beneficial performance characteristics for automotive lighting. Wheel systems remain within the domain of metals, except for decorative uses such as those found on hubcaps. 

True properties are determined by the polymer and compound formulation and, for synthetic rubbers, additionally by type of curing agents such as sulfur or peroxides and the state of vulcanization. Typical properties for four polymers often used in automotive applications [acetals, nylons, polycarbonates, and unsaturated polyester (vinyl esters)] are shown in Tables 10.1 through 10.4. Typical property data is readily available from resin producers and compounders. Property data for elastomers is found in the chapter on elastomers in this handbook. 

Polycarbonate properties that contribute to automotive applications include resistance to brittle fracture, clarity and optical precision, dimensional stabihty, impact strength, scratch resistance, and temperature resistance. 

Hardcoat systems of the type described in this paper can enable plastics to be used in applications for which they would otherwise be unsuitable, due to sensitivity of the plastic to UV degradation, chemical agents, or abrasion. The largest current market for these types of systems is automotive forward lighting applications, as protective coatings for clear polycarbonate headlamps. Other automotive applications include coatings for black polycarbonate side pillars and tinted... 

These have often been modified by addition of PE. Blends with polyoxymethylene showed complex anomalous behavior due to interfacial phenomena [34]. PE appeared useful as a melt flow promoter in polyphenylene ether [19]. Dispersion of PE in polycarbonate improves melt flow and energy absorption for automotive applications [19], so PC producers offer such grades commercially [35] fine stable polyethylene domains may be produced by adding PE-PS or SEBS block copolymers [36,37]. 

In the automotive market, cyanoacrylates are used to bond weatherstripping to automotive bodies and to position rubber gaskets before assembly. They are used to bond polycarbonate positioning clips to side windows of automobiles, alternator horn assembly components, and rubber gaskets to automotive thermostats. One of the most common automotive applications is the use of cyanoacrylates in the repair of flexible PVC side trim strips. 

Questra resins are used predominantly in automotive applications such as chassis/powertrain, electrical and coolant systems. Syndiotactic PS competes mainly with PBT, polycarbonate and ABS. 

Table 5.8 shows polycarbonate consumption in automotive applications by world region for the period 1999-2002. 

Table 5.8 Polycarbonate consumption in automotive applic period 1999-2002 (000 tonnes ations by world region for the ...

In 2002, total polycarbonate consumption in automotive applications was 283,000 tonnes against... 

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