Triaryl Phosphate TAP

TAP is used as a plasticizer in flame-retardant rubber compounds because the other plasticizers provide a fuel source that feeds a fire in the case of combustion. That is why many times this phosphate plasticizer is selected instead of other plasticizers. Recently, the use of triaryl phosphates has attracted attention again because of 

Historically, over time TAPs have been manufactured from feedstocks based on phenol, cresol, and/or xylenols. Different feedstocks will affect plasticizer performance and toxicity characteristics. Consult the latest government safety, health, and environmental regulations before choosing a specific grade of TAP for rubber use. 

ASTM D1992 is a standard guide for testing synthetic plasticizers. 

Many times rubber compounds require a piasticizer. However, most plasticizers or processing oils hurt flame retardancy because they provide a fuel source to a potential fire if there is combustion. If a plasticizer must be used, the correct type of triaryl phosphate should function as both a plasticizer and a flame retardant in both the gas and condensed phases. 

A variety of materials are commercially available for giving a rubber compound certain desired properties needed for functional performance in actual use. Antioxidants are commonly added for resistance against attack by environmental oxygen (Oj), whereas antiozonants are employed for resistance from attack by ozone (O3). 

---

Of this family of products, triaryl phosphates (TAP) and alkyl diaryl phosphates (ADP) are the two important categories of FR plasticizers for PVC. Trialkyl phosphates are considered too volatile for most vinyl processes, and are more commonly found in other applications, such as leveling agents or antifoam additives. In vinyl, TAP and ADP plasticizers are used to flame-retard thin films and laminates for articles such as wall covering, tarpaulins (transportation), and vinyl-coated furniture fabric. Another major application area is in vinyl for electrical insulation in wire and cable. In addition to these applications, phosphate esters are used as functional fluids for hydraulic equipment (metal industries, power generation, and aircraft hydraulic systems) and as additives in formulated lubricant systems. As flexible vinyl composites are usually defined by their additives, when formulated correctly, phosphate esters can help produce a very cost-efficient vinyl composite capable of very low smoke and flammabihty. In nearly all markets, phosphate esters are valued primarily for their FR properties, and the distinction from function and plasticization is sometimes obscured. 

The first commercial trialkyl phosphate esters (TAP) were tricresyl phosphate (TCP) and trixylenyl phosphate (TXP), referred to as "natural" phosphate esters because the cresols and xylenols used as raw materials are derived from petroleum oil or coal tar (Marino and Placek 1994). These products are not commercially significant at present however, at waste disposal sites, contaminants from older product formulations may be encountered, particularly those containing the neurotoxic tri-o/T/io-cresyl phosphate isomer. "Synthetic" phosphate esters are derived from synthetic feedstocks. Specific synthetic reactions have been developed to produce triaryl, trialkyl, and alkyl Aryl esters. The triaryl phosphates are currently... 

---