Battery cases, polypropylene

Polypropylene. Polypropylene (PP) is used ia packagiag appHcations as films and ia rigid containers. Battery cases could be considered another packagiag appHcation. Dead batteries are often collected at the poiat of sale of new batteries. In the U.S., some states have laws mandating this. Lead, acid, and plastics, particularly PP from battery casiags is recovered and recycled (3). Care must be taken to limit worker exposure to lead duting this process (44). PP is also recovered from bale wrap and other PP fabrics used for wrappiag ia the textile iadustry and from other containers (45). 

Eew of the products in which polypropylene are used can be recovered in commercial quaUties. An exception is battery casings. In 1994, U.S. capacity for recycling polypropylene from battery casings was 265 million pounds aimuaHy (45). About 75% of the recovered polypropylene is used in new battery cases which have a recycled PP content of about 50%. Total polypropylene recycling capacity was 350 million pounds aimuaHy for an operating rate estimated at 71—90% (45). 

Polypropylene is used in battery cases and in the replacement of metal parts in automobiles. It is also widely used in consumer products, eg, kitchen wares, trays, toys, and packaging materials. Its future appHcations are expected to include an increased portion of the fibers and filaments markets, especially for continued growth in carpet backing and carpet face yams. Film, both oriented and unoriented, is also expected to be a significant growth market for polypropylene. 

Prior to smelting, batteries are usually broken up and sorted into their constituent products. Fractions of cleaned plastic (such as polypropylene) case are recycled into battery cases or other products. The dilute sulfuric acid is either neutralized for disposal or recycled to the local acid market. One of the three main smelting processes is then used to reduce the lead fractions and produce lead bullion. 

Polypropylene (PP) is used in a variety of areas, from snack food packaging to battery cases to disposable diaper linings. It is frequently interchanged for polyethylene or polystyrene. 

Polypropylenes are available as molding powder, extruded sheet, cast film, textile staple, and continuous-filament yarn. They find use in packaging film molded parts for automobiles, appliances, and housewares wire and cable coating food container closures bottles, printing plates carpet and upholstery fibers storage battery cases crates for soft-drink bottles laboratory ware trays fish nets surgical casts and a variety of other applications. 

Propylene (C3H6) is a gas with chemical, physical, and toxicological properties very similar to those of ethylene. It, too, is a simple asphyxiant. Its major use is in the manufacture of polypropylene polymer, a hard, strong plastic from which are made injection-molded bottles, as well as pipes, valves, battery cases, automobile body parts, and rot-resistant indoor-outdoor carpet. 

A related situation we ll call piggyback markets. By this we mean industries in which extensive recycling exists for some material other than polymers, but in which polymers are easily separated for recycle as well. We earlier mentioned the recycling of polypropylene battery cases. Infrastructure was already in place to recover valuable lead metal from the electrodes. It was easy to also recover the plastic cases when polymer recycling became feasible. Table 9-3 summarizes a few examples. 

The second member of alkenes, propylene, can also be polymerized under suitable conditions. Polypropylene is used in the production of bottles, electric battery cases and rugs. 

Among the polypropylene products, the most recycled are the battery cases. Almost all automotive and truck battery cases are made of PP, and there is a well-established industry to recycle batteries in the United States, due to its lead contamination. Because of the combination of land disposal ban, and mandated delivery/take-back provisions, automotive batteries are recycled at a very high level. About 40 percent of the recovered PP is used again in battery production and the rest is used for making other injection-molded products. Some of the cleaner recycled PP can be used in libers, such as spunbond or meltblown nonwovens for geotextiles or filter applications. ... 

Reductant. Generally, coke or coal is used, but charcoal can be substituted. Ebonite from hard rubber batteries was previously used, mainly as a disposal route, but is now phased out following the decline in the use of the material as a battery case. Some processes smelt whole batteries and employ the polypropylene cases and separators as the reducing agent. 

The major challenge to all recovery systems will be the increasing level of other plastic types in the feed material. Materials such as ABS (acrylonitrile butadiene styrene) are being used in VRLA battery cases, due to their toughness and rigidity relative to traditional polypropylene. For the recycler, this means that the valuable polypropylene tonnage will fall with a reciprocal increase in plastic types that cannot be recycled. This material will have to be disposed of, as ABS and... 

Washed and dried polypropylene pieces are sent to a plastic recycler, where the chips are melted [12] and extruded to produce plastic pellets for use in the manufacture of battery cases and other plastic components. Great care must be taken to ensure that the mechanical breaker cleans the polypropylene chips free of any residual oxide, because subsequent handling of the chips by operating personnel, especially at the plastic recycling plant, can result in significant levels of lead exposure. Should the wash sprays on the breaker fail to remove all traces of battery paste, consideration should be given to further washing with a dilute sodium hydroxide solution. 

Impact modified polypropylene is used for injection molding automotive, consumer and appliance parts. For example, the medium impact PP is widely used for automotive interior trim. High impact PP is used for battery cases, fender and truck liners. Impact PP is also used extensively in the houseware and appliance markets. 

The ebonite battery case was replaced by polypropylene and polyethylene copolymer or by acrylonitrile butadiene styrene. 

By contrast, relatively uncontaminated single polymer types can be collected from retail outlets by segregation on site [e.g. discarded polypropylene crates, battery cases and supermarket shrink-wrap). These can be recycled with the addition of new antioxidants and UV stabilisers into the primary application, generally as a blend with virgin polymer, without significant loss of mechanical properties. 

Polypropylene, a homopolymer polyolefin engineering plastic provides excellent chemical resistance, purity and it is the lightest of all commercial plastics. PP offers innovative solutions to many challenges that face the automotive industry today. Its low density compared to traditional materials significantly contributes to fuel economy and reduced material costs. Its excellent noise, vibration, and harshness (NVH) properties contribute to enhanced passenger comfort. Thus, PP has become the most important thermoplastic material in automobile industry. PP homopolymers, random copolymers, and impact copolymers are used in products such as automotive parts and battery cases, carpeting, electrical insulation, and fabrics. 

Polypropylene, used in indoor-outdoor carpeting, bottles, fabrics, and battery cases, is made from propylene. 

Other Deposit Systems. The idea behind beverage bottle deposits has also been apphed to other products. Automobile batteries are subject to deposits in many states. While the primary motivation is to avoid the introduction of lead into landfills and incinerators, these systems have been very successful at facilitating the recycling of the polypropylene (PP) battery cases. Deposits are also common on tires. 

Lead-acid batteries are prohibited from MSW disposal facilities in 37 U.S. states, primarily due to concern about the effects of lead. Several states impose deposits on batteries. Effective recycling programs for these batteries have existed for a number of years. The Battery Council International reports a 2003 recycling rate of more than 97 percent for lead-acid batteries. Polypropylene makes up about 7 percent of the battery, by weight, and is recovered along with the lead. The primary market for the recovered PP is new battery cases. A typical battery contains 60 to 80 percent recycled PP. The recycling rate for the cases can be assumed similar to that for batteries. ... 

Recycling of PP battery cases also takes place outside the United States. Germany began such recycling in 1984, yielding about 3000 tonnes/year of polypropylene. The process involves crushing the batteries... 

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