Paraffin, chlorinated

Chlorinated paraffins with the general molecular formula x 2x-y+2) have been manufactured on a commercial basis for over 50 years. The early products were based on paraffin wax feedstocks and were used as fine retardants and plasticizers in surface coatings and textile treatments and as extreme pressure—antiwear additives in lubricants. The development of chlorinated paraffins into new and emerging technologies was constrained principally because of the limitations of grades based on paraffin wax and the lack of suitable alternative feedstocks to meet the demands of the new potential markets. 

In the early 1960s the petroleum industry employing molecular sieve technology made available a low cost and plentihil supply of normal paraffin fractions of very high purity. This enabled chlorinated paraffin manufacturers to exploit new appHcations with a range of products specifically designed to meet the technical and commercial requirements. 

The principal feedstocks used today are the normal paraffin fractions CIO—C13, C12—C14, C14—C17, and C18—C20 together with paraffin wax fractions of C24—C30, precise compositions may vary depending on petroleum oil source. Chlorination extent generally varies from 30 to 70% by weight. The choice of paraffinic feedstock and chlorine content is dependent on the appHcation. 

By virtue of the nature of the paraffinic feedstocks readily available, commercial chlorinated paraffins are mixtures rather than single substances. The degree of chlorination is a matter of judgment by the manufacturers on the basis of their perception of market requirements as a result, chlorine contents may vary from one manufacturer to another. However, customers purchasing requirements often demand equivalent products from different suppHers and hence similar products are widely available. 

The physical and chemical properties of chlorinated paraffins are deteanined by the carbon chain length of the paraffin and the chlorine content. This is most readily seen with respect to viscosity (Fig. 1) and volatiUty (Fig. 2) increasing carbon chain length and increasing chlorine content lead to an increase in viscosity but a reduction in volatiUty. 

The toxicology of the chlorinated paraffins as a group is not considered very serious and they are not considered to be one of the most adverse ecological threats. Among all possible chlorinated substances in this group, however, some do exert adverse effects and so the use of chlorinated paraffin products should be restricted (Tomy et al., 1998). 

An advantage of the system is that coupling can be delayed until the injection molding process, which can improve processability and effectiveness. The dehydrochlorination can be accelerated by the presence of alkaline species such as magnesium oxide, which also neutralizes the corrosive hydrogen chloride evolved. Other additives, such as maleic anhydride, peroxides, and organosilanes, can be incorporated. 

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Anti-wear and extreme pressure additives phosphoric esters, dithiophosphates, sulfur-containing products such as fatty esters and sulfided terpenes or chlorinated products such as chlorinated paraffins. 

Both chloramine-T and dichloramine-T slowly liberate hypochlorous aeid in eontaet with water and are therefore employed as antiseptics the former is employed in the form of a dilute (e.g., 0-2 per eent.) aqueous solution, and the latter (which is insoluble in water) as a solution in an organic solvent, such as a chlorinated paraffin. 

Cm.OROCARBONSANDCm.OROHYDROCARBONS - TOXIC AROMATICS] (Vol 6) Chlorinated paraffin C12 and 58%... 

Zinc Sta.nna.tes, The zinc staimates are also effective synergists for flexible PVC however, as shown in Figure 4a, antimony oxide is more effective. If more chlorine such as in a chlorinated paraffin such as Cereclor is added, then the staimates become more effective and eventually outperform antimony oxide (Fig. 4b). 

Suggested formulations for various polymers using hexabromocyclododecane (HBCD), a brominated aHphatic a chlorinated paraffin, ie, a chlorinated aHphatic and decabromodiphenyl oxide, a brominated aromatic, are shown in Tables 2—4. These suggested formulations may not be strictiy comparable because of differences in the nature of the base resins. However, the suggestions are specific to a given UL-94 rating. 

Based on 70% chlorine content. For chlorinated paraffins having lower chlorine content, the use level must be raised accordingly. 

A significant advance in flame retardancy was the introduction of binary systems based on the use of halogenated organics and metal salts (6,7). In particular, a 1942 patent (7) described a finish for utilizing chlorinated paraffins and antimony(III) oxide [1309-64-4]. This type of finish was invaluable in World War II, and saw considerable use on outdoor cotton fabrics in both uniforms and tents. 

Other sources of by-product HCl include allyl chloride, chlorobenzenes, chlorinated paraffins, linear alkylbenzene, siHcone fluids and elastomers, magnesium, fluoropolymers, chlorotoluenes, benzyl chloride, potassium sulfate, and agricultural chemicals. 

Vista, Huntsman, and other linear alkylben2ene (LAB) producers feed chlorinated paraffins to an alkylation reactor to produce detergent alkylate without prior separation of the unreacted paraffins. Large amounts of paraffins must be recycled in these processes. 

Flame retardants such as a-alumina trihydrate [14762-49-3] can be added to latex-based foamed carpet backing a combination of antimony oxide [1309-64-4] and chlorinated paraffins is used in dry mbber. 

Peroxides or other additives, eg, chlorinated paraffin, may also cause the thermoplastic resin to cross-link with the siloxanols. In this case, a tme interpenetrating polymer network forms, in which both phases are cross-linked. 

Chlorinated paraffins. Chlorinated ben2enes. Ring-chlorinated toluenes. Benzyl chloride. 

Fig. 2. Volatility of chlorinated paraffins at 180°C after four hours. Paraffin feedstock A, wax B, C14—C17 C, CIO—C13.

Chlorinated paraffins vary in their physical form from free-flowing mobile Hquids to highly viscous glassy materials. Chlorination of paraffin wax (C24—C30) to 70% chlorine and above yields the only soHd grades. Physical properties of some commercially available chlorinated paraffins are Hsted in Table 1. 

Table 1. Physical Properties of Selected Commercial Chlorinated Paraffins...

A key property associated with chlorinated paraffins, particularly the high chlorine grades, is nonflammability, which has led to their use as fire-retardant additives and plasticizers in a wide range of polymeric materials. The fire-retardant properties are considerably enhanced by the inclusion of antimony trioxide. 

Chlorinated paraffins are relatively inert and exhibit excellent resistance to chemical attack and are hydrolytically stable. They are soluble in chlorinated solvents, aromatic hydrocarbons, esters, ketones, and ethers but only moderately soluble in ahphatic hydrocarbons and virtually insoluble in water and lower alcohols. 

Chlorinated paraffins are manufactured by passing pure chlorine gas into a Hquid paraffin at a temperature between 80 and 100°C depending on the chain length of the paraffin feedstock. At these temperatures chlorination occurs exothermically and cooling is necessary to maintain the temperature at around 100°C. Catalysts are not usually necessary to initiate chlorination, but some manufacturers may assist the process with ultraviolet light. Failure to control... 

In order to operate an economically viable chlorinated paraffin business, it is essential to have a profitable outlet for the surplus hydrochloric acid, either through direct sales into the market, or preferably via an oxychlorination unit in an integrated vinyl chloride/chlorinated solvent unit, while still maintaining the option of direct sales. 

Chlorinated paraffins are versatile materials and are used in widely differing appHcations. As cost-effective plasticizers, they are employed in plastics particularly PVC, mbbers, surface coatings, adhesives, and sealants. Where required they impart the additional features of fire retardance, and chemical and water resistance. In conjunction with antimony trioxide, they constitute one of the most cost-effective fire-retardant systems for polymeric materials, textiles, surface coatings, and paper products. Chlorinated paraffins are also employed as components in fat Hquors used in the leather industry, as extreme pressure additives in metal-working lubricants, and as solvents in carbonless copying paper. 

Plasticized PVC. Chlorinated paraffins are employed as secondary plasticizers with fire-retardant properties in PVC and can be used as partial replacements for primary plasticizers (qv) such as phthalates (1) and phosphate esters (2). 

By selection of those chlorinated paraffins specifically developed for the PVC industry to match the properties of primary plasticizers, reductions in costs can be achieved without significant change in properties. However, certain aspects can be improved by the inclusion of chlorinated paraffin such as flame resistance, chemical and water resistance, low temperature performance, and the viscosity aging stabiUty in plastisols. 

The selection of chlorinated paraffin and the level of additives to a lubricating oil depends on the type of appHcation and the severity of the operation. An approximate guide for the formulation of straight-cutting oils for metal-working is as foUows ... 

Paints. Chlorinated paraffins are used as plasticizers for paints based on many types of resins, particularly chlorinated mbber and vinyl copolymers. Chlorinated mbber-based paints are employed in aggressive marine and industrial environments and vinyl copolymer principally for the... 

The largest single market is the United States at approximately 40,000 t. Europe as a whole is approximately two and a half times greater than the United States mainly because of the extensive use of chlorinated paraffins as secondary plasticizers in plasticized PVC, which is virtually absent in the United States. 

Although chlorinated paraffins are manufactured throughout the world, the principal centers of production are Europe, North America, and Japan. ICI is the leading suppHer having its main production centered in Europe, but it has a number of plants around the world including North America. 

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