Phosphate plasticizer level

Table IV. Outdoor Exposure Data at a Phosphate Plasticizer Level...

Raw Materials. PVC is inherently a hard and brittle material and very sensitive to heat it thus must be modified with a variety of plasticizers, stabilizers, and other processing aids to form heat-stable flexible or semiflexible products or with lesser amounts of these processing aids for the manufacture of rigid products (see Vinyl polymers, vinyl chloride polymers). Plasticizer levels used to produce the desired softness and flexibihty in a finished product vary between 25 parts per hundred (pph) parts of PVC for flooring products to about 80—100 pph for apparel products (245). Numerous plasticizers (qv) are commercially available for PVC, although dioctyl phthalate (DOP) is by far the most widely used in industrial appHcations due to its excellent properties and low cost. For example, phosphates provide improved flame resistance, adipate esters enhance low temperature flexibihty, polymeric plasticizers such as glycol adipates and azelates improve the migration resistance, and phthalate esters provide compatibiUty and flexibihty (245). 

Plasticization of PVC for improved flame retarding properties usually relies on the combination of phosphate plasticizers with other plasticizers or inorganic additives listed in the previous paragraph. The selection of the combination depends on the level of protection required. 

Plasticizers are high-boiling liquids which are solvents for PVC increasing addition reduces the Tg value of PVC until the material is rubbery, usually at levels above 30 phr by weight. Most commonly used plasticizers are Cg to C q derivatives of phthalic acid, e.g. dioctyl phthalate (DOP) and didecyl phthalate (DDP) the latter is less water-extractable, hence finding use for baby-pants. Phosphate plasticizers (e.g. trixylyl phosphate) are more expensive, more toxic but effectively enhance fire resistance. Aliphatic acid esters with Cg to C o are normally used in combination with phthalate plasticizers. 

Because of their relatively low molecular weight, solution PVC/VA resins are formulated with plasticizer levels of 0-25 phr. These are useful not only in improving flexibility but also in minimizing solvent retention in the coating. Most commonly, general purpose phthalate plasticizers (DOP, DINP) are used. For increased flexibility, linear phthalates are used, and for least volatility, DIDP, DTDP, and trimellitates. Phosphate plasticizers are used in flame-retardant applications, and polymeric polyesters where resistance to migration or extraction is required. 

Plasticizers Polar plasticizers such as esters decrease surface resistivity of nonblack compounds hydrocarbon secondary plasticizers provide increased levels. Unplasticized PVC without a surface coating of paraffin wax has a surface resistivity of about 10 ohm. Addition of 40 phr of ester plastieizer decreases this to 10 °-10 ohm. Phosphate plasticizers can lower surface resistivity by several orders of magnitude. In addition, the mobility (lowering of glass transition temperature) of the plasticizer is a factor. Low-temperature plasticizers are found to have an increased effect in lowering surface resistivity. When substituting, for example, an adipate or oleate for a phthalate to lower surface resistivity (in cases where the application permits), it must be considered that the former are more available microbial nutrients. 

In vinyl plasticized with various levels of a readily flammable ester, for example DOP, LOI will rise gradually with each part of antimony trioxide, up to about 5-7 parts, at which point it will tend to level off. At about 75 phr flammable plasticizer, this will limit compositions to about 25 percent LOI, usually sufficient to pass horizontal but not vertical flame tests. At 30-50 phr plasticizer, 5-7 phr antimony trioxide will provide an LOI of 30-35, adequate for simple vertical tests. Substitution of zinc borate for antimony trioxide in such systems will result uniformly in lower LOI, but use instead of a 1 1 blend will generally duplicate results with antimony trioxide alone because of their synergistic effect. Zinc borate does not appear to interfere with gas-phase action of antimony plus chlorine. One-third replacement of flammable plasticizer with chlorinated paraffin will result in a greater increase in LOI per part antimony trioxide added. The effects of replacement with FR phosphate plasticizers are discussed in Chapter 9. 

Tris(2-chloroethyl) phosphate is used as a flame retardant in plastics, especially in flexible foams used in automobiles and furniture, and in rigid foams used for building insulation. No data on occupational exposure levels were available. Tris(2-chloroethyl) phosphate has been detected in drinking-water, river water, sea water and sediments in various parts of the world (IARC, 1990). 

Triphenylphosphate is a colorless, odorless, crystalline solid (mp, 49°C bp, 245°C). It is moderately toxic. A similar, but much more toxic, compound is tri-o-cresyl-phosphate (TOCP), an aryl phosphate ester with a notorious record of poisonings.3 Before its toxicity was fully recognized, TOCP was a common contaminant of commercial tricresylphosphate. Tricresylphos-phate is an industrial chemical with numerous applications and consists of a mixture of phosphate esters in which the hydrocarbon moieties are meta and para cresyl substituents. It has been used as a lubricant, gasoline additive, flame retardant, solvent for nitrocellulose, plasticizer, and even a cooling fluid for machine guns. Although modem commercial tricresylphosphate contains less than 1% TOCP, contaminant levels of up to 20% in earlier products have resulted in severe poisoning incidents. 

When applying the conventional food contact ratio the worst-case migration potential did not exceed the SML for any of the substances derived from plastics nor did the calculated worst-case exposure exceed the ADI/TDI or other exposure restriction value in any products. However, when the actual food contact ratio was applied the ADI/TDI or other exposure restriction value of several substances could theoretically be exceeded. The worst-case calculations assume that intimate contact is made with the entire surface of the packaging. This is not the case for the majority of snack foods that are solids or semi-solids and so the actual area of contact made will be less than the total area available for contact (e.g. crisps). The levels of those migrants (diisobutyl phthalate, dicyclohexyl phthalate, dibutyl sebacate, diphenyl 2-ethylhexyl phosphate and 2-ethyl-1-hexanol) that had the potential to exceed the assigned restrictions, assuming 100% migration, were determined in foods. Of the five substances tested for, only one, dicyclohexyl phthalate, was detected in one of the foodstuffs (tortilla corn chips), at a concentration of 0.60 ppm. 

KP>i4) . [FMC] Tributoxyethyl phosphate leveling agent in floor polishes flame retardant for plastics and rubbers. 

Plasticizers can also be used in polyurethane adhesives to lower viscosity, improve filler loadings, improve low-temperature performanee, and plastieize the polynrethane adhesive. Phthalate esters, benzoate esters, phosphates, and aromatie oils are common examples [48]. Plasticizers should be used sparingly, as adhesion will generally decrease as levels increase. 

The low-volatility, flame-resistant phosphoric acid esters have maintained their position in products subjected to high levels of mechanical strain such as conveyor belts. Triphenyl phosphate, used only for molding compounds made of cellulose esters, is a practically noncombustible product that is not soluble in benzine. Tricresyl phosphate (TCP) is a flame-retardant plasticizer for PVC products subjected to heavy mechanical stress. The esters of the aliphatic dicarboxylic acids (adipic, azelaic, and sebacic acid) are used as plasticizers for PVC and PVAC. These products are resistant to cold and light. The esters of higher fatty acids such as pelargonates, laurates, palmitates, stearates, and ricinoleates are, strictly speaking, not plasticizers, but are rather used as extenders, secondary plasticizers, or lubricants. 

Chem. Descrip. Tributoxyethyl phosphate CAS 78-51-3 EINECS/ELINCS 201-122-9 Uses Flame retardant, plasticizer for plastisols, acrylics, cellulosics, epoxy, nitrile rubber, PVAc floor polish emulsions leveling agent in latex paints and polishes Imparts low temp, flexibility to syn. rubbers antifoam In paper coatings. Inks, textile sizes, detergents, and paints Properties Colorless liq. sp.gr. 1.35 (20/20 C) vise. 12 mPa s 7.8% P Phosflex TPP [Akzo Nobel]... 

Ultra-small concentrations in sub-parts-per-billion levels of plasticizers in ultrapure water can seriously undermine cleaning efficiency of silicon wafers. Thermal desorption-gas chromatography-mass spectrometry was successfully used to determine these very small quantities of plasticizers. " Many plasticizers such as texanol, trichloroethyl phosphate, diethyl phthalate, dibutyl phthalate, benzyl butyl phthalate, dioctyl phthalate and dioctyl adipate were identified in water at lower than 0.2 ppb levels. " ... 

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