Polycarbonate compact discs

To maximize control in setting tolerances there is usually a minimum and a maximum limit on thickness, based on the process to be used such as those in Tables 3-6 to 3-9. Each plastic has its own range that depends on its chemical structure, composition (additives, etc.), and melt-processing characteristics. Any dimensions and tolerances are theoretically possible, but they could result in requiring special processing equipment, which usually becomes expensive. There are of course products that require and use special equipment such as polycarbonate compact discs (CDs) to meet extremely tight tolerances. 

The pace of development has increased with the commercialization of more engineering plastics and high performance plastics that were developed for load-bearing applications, functional products, and products with tailored property distributions. Polycarbonate compact discs, for example, are molded into a very simple shape, but upon characterization reveal a distribution of highly complex optical properties requiring extremely tight dimension and tolerance controls (3,223). 

Polycarbonate compact discs have also been used as supports for microarray development [112]. The microarray is generated using an inkjet applicator that employs an electric current to dispense monodisperse droplets containing antibodies onto the disk. The sensing reaction is based on competitive inhibition immunoassays using fluorescent antibodies and final readout is accomplished using a fluorescence scanner. 

A compact disc-based microarray system was developed by Kido et and used for immunoassays. They used a piezoelectric inkjet applicator to deposit the proteins onto a polycarbonate disc. Recently, Clair et al. reported the attachment of small molecules to a polycarbonate compact disc (CD) surface via phosphodiester bonds. Molecular interactions between analytes and some of these molecules can be detected with a conventional CD player. ... 

Beverage bottles baby milk bottles, non-packaging uses for polycarbonate compact discs unbreakable" glazing electronic e.g. PMMA, nylon, goods, apparatus housings O often PC or ABS... 

The growth rate of 4-cumylphenol is expected to parallel the growth rate of polycarbonates, particularly the grades used to produce compact discs (see Table 3). 

For many years vinyl chloride-vinyl acetate copolymers had two main uses, in flooring compositions and for long playing gramophone records. Whereas the former application remains strong, the use in gramophone records has dropped sharply, particularly since the widespread acceptance of polycarbonate-based compact discs. 

PMMA has not been able to compete in the field of compact discs, the market having gone to the polycarbonates (see Chapter 20). It is, however, suitable for optical data storage using large video discs. Large-scale acceptance in the field of optical fibres has been held back by problems of obtaining material of an acceptable level of purity. 

Just as many small-molecule materials, polymers also form glasses [4]. Actually, most polymeric materials of everyday use are made of polymer glasses, polystyrene (PS) cups or compact discs made of polycarbonates, for instance. In many respects polymer glasses are very similar to small-molecule glasses, and there is nothing special about them. However, on the other hand, the special aspects of polymer materials allow specific studies beyond characteristic studies on small-molecule glasses. 

Glassy amorphous polymers exhibit excellent dimensional stability and are frequently transparent. Everyday examples include atactic polystyrene, polycarbonate, and polymethylmethacrylate (Plexiglas ), which we encounter in such applications as bus shelters, motorcycle windshields, and compact disc cases. 

The functional groups that typically participate in this type of polymerization are carboxyl, amine, and alcohol groups. Examples of step growth polymers include polyesters and nylons, which are often spun into fibers used to manufacture carpeting and fabrics, and polycarbonates, which are converted into compact discs, jewel cases, and the large bottles used in water coolers. 

The result was the compact disc (CD). Made from 1.2 mm of polycarbonate plastic, the disc is coated with a much thinner aluminum layer that is then protected with a film of lacquer. The lacquer layer (10) can be printed with a label. CDs are typically 120 mm in diameter, and can store about 74 minutes of music. There are also discs that can store 80, 90, 99, and 100 minutes of music, but they are not as compatible with various stereos and computers as the 74—minute size. 

The major uses of BPA are in the production of polycarbonate resins (63%) and epoxy resins (27%). Polycarbonates have major outlets in automotive parts, compact discs, eyeglasses, and sheet and glazing applications, and have caused bisphenol A consumption to more than double during the past decade. Epoxy resins are two-component adhesives for very strong bonding. Miscellaneous uses include flame retardants (mostly tetrabromobisphenol A) and other polymer manufacture. Polycarbonate grade bisphenol A is >99% p,p isomer. The epoxy grade is 95% p,p. The p,p and o,p isomers can be separated by a combination of distillation and crystallization. 

In addition to the construction industry, phenol has many other applications. It is used in pharmaceuticals, in herbicides and pesticides, and as a germicide in paints. It can be used to produce caprolactam, which is the monomer used in the production of nylon 6. Another important industrial compound produced from phenol is bisphenol A, which is made from phenol and acetone. Bisphenol A is used in the manufacture of polycarbonate resins. Polycarbonate resins are manufactured into structural parts used in the manufacture of various products such as automobile parts, electrical products, and consumer appliances. Items such as compact discs, reading glasses, sunglasses, and water bottles are made from polycarbonates. 

Fig. 50. a SFM picture of an indentation of the letter T on PMMA with a nickel tip. Force used for the imaging was 10"6N. b Profile along the line drawn in (a). Reproduced from [416]. c HEUREKA written with the dynamic ploughing technique on a compact disc (CD) of polycarbonate. The holes are information pits in the disc. The letter height is 700 nm, and the indentation depth is 10 nm. Reproduced from [464]... 

Polycarbonates are amorphous polymers with excellent handling properties. Their spectrum of applications ranges from baby bottles to compact discs. Most of the polycarbonate produced is generated by the polycondensation of bisphenol A with phosgene in a biphasic system (sodium hydroxide/dichloromethane). The solution of the polycarbonate product in dichloromethane is washed with water to remove the by-product NaCl. However, in this washing process some 20 g L 1 of the dichloromethane ends up dissolved in the aqueous phase. The dichloromethane must also be removed from the polycarbonate, which is not easy. This means that the polycarbonate will invariably contain some chlorinated impurities, which adversely affects the properties of the polymer. 

This process—injection compression moulding—offers other advantages besides lower clamping forces compression of the hot melt gives excellent surface finish and lower pressure at injection reduces orientation in the melt, so improving dimensional stability. The method is used currently to make compact discs of high quality from polycarbonate. 

Polyesters with two ester groups bonded to the same carbon are known as polycarbonates. Lexan is produced by the reaction of phosgene with bisphenol A. Lexan is a strong, transparent polymer used for bulletproof windows and traffic-light lenses. In recent years, polycarbonates have become important polymers in the automobile industry as well as in the manufacture of compact discs. 

Figure 22.16 Compact discs are made of polycarbonate and contain long chains of the structural unit shown. 

For the use as basic material for compact discs PMMA and polycarbonate are the preferred polymers. But the two polymers have the disadvantage, that they become... 

Phosgene is a highly toxic gas that has been used as a chemical weapon at times in the past. It is now used in the manufacture of polycarbonates, which are used to make compact discs and plastic eyeglass lenses. Phosgene is produced by the reaction, CO + CI2 — COCI2. Given an excess of carbon monoxide, what mass of chlorine gas must be reacted to form... 

Some recycling of polycarbonate from products such as automobile bumpers, compact discs, computer housings, and telephones has been carried out. 

Bayer built Europe s first polycarbonate CD recycling facility in Leverkusen, Germany, in 1995. The PC was separated from aluminum coatings, protective layers, and imprinting. The product was blended with virgin PC for use in a variety of products. In Europe, Bayer recycles returnable polycarbonate bottles and jars used by dairies as well as compact discs. SS... 

Polymers play a vital part in optical recording media, mainly as the substrate material. Polycarbonate is the material of choice for Compact Disc substrates. However, in particular for magneto-optic rewritable disc substrates it could be attractive to reduce the birefringence not only by optimizing the moulding process, but also by modifying the material towards a lower orientational stress optical coefficient. Work at our laboratories has shown that this can be achieved... 

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