Polycarbonate flame-retardant applications

Blending two or more polymers offers yet another method of tailoring resins to a specific application. Because blends are only physical mixtures, the resulting polymer usually has physical and mechanical properties that lie somewhere between the values of its constituent materials. For instance, an automotive bumper made from a blend of polycarbonate resin and thermoplastic polyurethane elastomer gains rigidity from the polycarbonate resin and retains most of the flexibility and paintability of the polyurethane elastomer. For business machine housings, a blend of polycarbonate and acrylonitrile-butadiene-styrene (ABS) copolymer resins offers the enhanced performance of polycarbonate flame retardance and ultraviolet (UV) stability at a lower cost. 

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. 

Flame retardants - [TEXTILES-FINISHING] (Vol 23) - [ALUMENUMCOMPOUNDS - INTRODUCTION] (Vol2) -antimony as [ANTIMONY AND ANTIMONY ALLOYS] (Vol 3) -antimony compds as [ANTIMONY COMPOUNDS] (Vol 3) -antimony compds as [ANTIMONY COMPOUNDS] (Vol 3) -based on ammonium sulfamate [SULFAMIC ACID AND SULFAMATES] (Vol 23) -bromine in [BROMINE] (Vol 4) -in electronic applications [PACKAGING - ELECTRONIC MATERIALS] (Vol 17) -iron fluoride in mfg of [FLUORINE COMPOUNDS, INORGANIC - IRON] (Vol 11) -nickel compounds as [NICKEL COMPOUNDS] (Vol 17) -phosphorus for [PHOSPHORUS] (Vol 18) -polycarbonates in [POLYCARBONATES] (Vol 19) -from propylene oxide [PROPYLENE OXIDE] (Vol 20) -for rubbers [RUBBERCHEMICALS] (Vol 21) -use m electrical connectors [ELECTRICAL CONNECTORS] (Vol 9)... 

The largest volume use of phosphorus-based flame retardants may be in plasticized vinyl. Other use areas for phosphorus flame retardants are flexible urethane foants. polyester resins and other thermoset resins, adhesives. textiles. polycarbonate-ABS blends, and some Other thermoplastics. Development efforts are well advanced lo find applications for phosphorus flame retardants, especially ammonium polyphosphate combinations, in polyolefins, and red phosphorus in nylons, Interest is strong in finding phosphorus-bused alternatives to those halogen-containing systems which have encountered environmental opposition, especially in Europe. 

Polycarbonate and ABS are not miscible, but blends are compatible and have excellent toughness. PC-ABS blends are also flame retarded with aromatic phosphates. These blends are typically very high in polycarbonate (70-80%) and also contain at least 10% of an organic phosphate. PC-ABS blends are preferred for unpainted applications because of their excellent UV stability. 

The primary use of TBBPA is as a flame retardant in epoxy resin circuit boards and in electronic enclosures made of polycarbonate-acrylonitrile-butadiene-styrene (PC-ABS). Other applications of TBBPA include its use as a flame retardant for plastics, paper, and textiles as a plasticizer in adhesives and coatings and as a chemical intermediate for the synthesis of other flame retardants (e.g., TBBPA allyl ether). It is also been applied to carpeting and office furniture as a flame retardant. 

The other important diol which finds wide application in synthesis of flame retardant epoxy thermosets is 4,4 -isopropylidene bis(2,6-dibromo-phenol) (tetrabromobisphenol-A,TBPA).The primary use of TBPA is as a reactive flame retardant in epoxy resin-based circuit boards and in electronic enclosures made of polycarbonate-acrylonitrile, butadiene-styrene, etc. Hexafluorobisphenol-A (bisphenol-AF, hexafluoroisopropylidene diphenol) has also been used for the synthesis of fluorinated epoxy resin aiming at the anticorrosion coatings market for industrial vessels and pipes. The key disadvantages of fluorinated epoxies are their relatively high costs and low Tg, which limit their commercialisation. Thus utilisation of such diols in vegetable oil-based epoxy resins may result in similar performance. 

Thermoplastic polyolefin-based nanocomposites have found applications in the step assist for GM Astro vans and film for food and pharmaceutical packaging. Polycarbonate- and ABS-based nanocomposites can be used for flame retardant computer housing and flame retardant monitor housing. Elastomer-based nanocomposites are finding use in tennis balls. 

Polycarbonate (PC) has excellent mechanical strength, particularly impact strength, good electrical properties and transparency, and is widely utilised in a variety of fields including office machinery, electric and electronic machinery, automobiles, architecture and so on. Many applications require that a PC composition be flame retardant(s) (FR) and combine ease of processing with good optical properties. Table 2.7 illustrates some of the physical properties of PC. 

Another property combination offered by polycarbonate is transparency with inherent, nonhalogenated flame retardancy. There are many applications where it is desirable to be able to see electrical connections, or where transparency helps make an application less obtrusive, such as telephone connector jacks. Still other applications exist where it is beneficial to have a window in an enclosure to be able to observe what is happening inside a device. Especially in applications... 

Triphenyl Phosphate [115-86-6]. This is a colorless solid, mp 48-49°C, nsnally produced in the form of flakes or shipped in heated vessels as a liquid. It is available from Akzo Nobel as PHOSFLEX TPP. An early application was as a flame retardant for cellulose acetate safety film. It is also used in cellulose nitrate, various coatings, triacetate film and sheet, and rigid urethane foam. It has been used as a flame-retardant additive for engineering thermoplastics such as polyphenylene oxide-high impact polystyrene and ABS-polycarbonate blends. 

Aromatic polycarbonates containing diphenylphosphine oxide units attached laterally to the chain (using the diol made by adding diphenylphosphine oxide to benzoquinone) have been shown in a General Electric patent to achieve flame retardancy without loss of Tg or impact strength (50). The required intermediate, diphenylphosphinous chloride, is commercially available, but this application has not been commercialized. 

Some specific recent applications of the chromatography-mass spectrometry technique to various types of polymers include the following PE [130, 131], poly(l-octene), poly(l-decene), poly(l-dodecene) and 1-octene-l-decene-l-dodecene terpolymer [132], chlorinated polyethylene [133], polyolefins [134,135], acrylic acid, methacrylic acid copolymers [136, 137], polyacrylate [138], styrene-butadiene and other rubbers [139-141], nitrile rubber [142], natural rubbers [143,144], chlorinated natural rubber [145,146], polychloroprene [147], PVC [148-150], silicones [151,152], polycarbonates (PC) [153], styrene-isoprene copolymers [154], substituted PS [155], polypropylene carbonate [156], ethylene-vinyl acetate copolymer [157], Nylon 6,6 [158], polyisopropenyl cyclohexane-a-methylstyrene copolymers [195], cresol-novolac epoxy resins [160], polymeric flame retardants [161], poly(4-N-alkylstyrenes) [162], pol)winyl pyrrolidone [31,163], vinyl pyrrolidone-methacryloxysilicone copolymers [164], polybutylcyanoacrylate [165], polysulfide copolymers [1669], poly(diethyl-2-methacryloxy) ethyl phosphate [167, 168], ethane-carbon monoxide copolymers [169], polyetherimide [170], and bisphenol-A [171]. 

Keywords 4,4 -Isopropylidenediphenol, Bisphenol-A, synthesis, catalysts, applications, epoxy resins, polycarbonates, polysulphone, polyetherimide, flame retardants, human health, environmental safety... 

But, the greatest growth of BPA production started at the beginnings of the Age of Plastic in the 1950s. At that time, industrial fabrication of polycarbonates and epoxy resins started [12], and Bisphenol-A became the primary monomer for their synthesis. As a difunctional monomer, later on BPA became one of the most important raw material used for synthesis of other polymers as well as polymer additives. Now, BPA is also used in the production of polyesters, polysulphones and polyether ketones. Its use for formulation and preparation of polymer additives (e.g., antioxidants, plasticizers, polymerization inhibitors and halogenated flame retardants) is still its another important application. 

Iji, M. Serizawa, S. New silicone flame retardant for polycarbonate and its derivatives, in S. Al-Malaika, A. Golovoy, and C.A. Wilkie, Eds., Specialty Polymer Additives. Principles and Applications. Blackwell Science, Oxford, England, 2001, pp. 293-302. 

Polycarbonate (PC)/acrylonitrile-butadiene-styrene (ABS) represents a typical blend that from its commercial introduction in the 1960s has become a major material in the automotive industry, as well as applications in business machine and electronic sectors. The blends provide the balance of properties required for these applications at an economic cost. These include low temperature ductility/impact and processability including injection moulding, extrusion and thermoforming. The commercial growth has been maintained by developments in heat stability, thermal ageing in hot wet environments and halogen free flame retardency [8]. 

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