Polychloroprene flame resistance

Neoprenes. Of the synthetic latices, a type that can be processed similarly to natural mbber latex and is adaptable to dipped product manufacture, is neoprene (polychloroprene). Neoprene latices exhibit poor initial wet gel strength, particularly in coagulant dipped work, but the end products can be made with high gum tensile strength, oil and aUphatic solvent resistance, good aging properties, and flame resistance. There are several types of neoprene latex, available at moderately high (ca 50 wt %) and medium soHds content. Differences in composition between the types include the polymer s microstmcture, eg, gel or sol, the type of stablizer, and the total soHds content (Table 22). 

Processing ndProperties. Neoprene has a variety of uses, both in latex and dry mbber form. The uses of the latex for dipping and coating have already been indicated. The dry mbber can be handled in the usual equipment, ie, mbber mills and Banbury mixers, to prepare various compounds. In addition to its excellent solvent resistance, polychloroprene is also much more resistant to oxidation or ozone attack than natural mbber. It is also more resistant to chemicals and has the additional property of flame resistance from the chlorine atoms. It exhibits good resiUence at room temperature, but has poor low temperature properties (crystallization). An interesting feature is its high density (1.23) resulting from the presence of chlorine in the chain this increases the price on a volume basis. 

The same company has developed a new generation of highly flame resistant open cell flexible PU/CR hybrid foam materials. The polyurethane and chloroprene are prepared using a brand-new technology called Foam-One. This is a batch process for making flexible slabstock under variable pressure that may range from 1 psi to 25 psi. PU base foams are post-treated with a polychloroprene compound to obtain the hybrid grades. 

Elastomers used for connector insulators include polychloroprenes, silicones, fluoro-silicones and heat-setting compounds which enable the special characteristics to be incorporated for example, flame resistance, low toxicity and low smoke. Neoprene is used as spacer material and also for washers where its sealing qualities, good resistance to cracking, rotting, oils and petrol and its good low temperamre flexibility may be beneficial in specific applications. 

Polychloroprene is stable to oxidation and ozone. It also has flame resistance, and its oil... 

Fillers. Addition of fillers is not common in polychloroprene latex formulations. Fillers are used to reduce cost and control rheology, solids content and modulus. However, cohesion and adhesion are reduced. Calcium carbonate, clay and silica are some of the fillers than can be added. Alumina trihydrate is often used when resistance to degradation by flame is important. 

The chlorine atom also confers an increased level of resistance to oils, so that the oil resistance of polychloroprene is roughly intermediate between natural rubber and nitrile rubber, and is often sufficient for many applications. Polychloroprene is also self-extinguishing in flame tests. 

Neoprene, or polychloroprene rubber (CR) was one of the very first synthetic rubbers produced. It was a material of choice for exterior applications such as profiles used in vehicles, building seals, and cables. Many more marketable products have benefited from this plastic. Except for SBR and IR, neoprene (CR) elastomers are perhaps the most rubberlike of all materials, particularly with regard to its dynamic response (Table 2.6). CRs are a family of elastomers with a property profile that approaches that of NRs (natural rubbers) but has better resistance to oils, ozone, oxidation, and flame. CRs age better and do not soften up on exposure to heat, although their high-temperature tensile strength may be lower than that of NRs. They are suitable for service at 250C (480F). 

Consideration is given to the influence of combinations of zinc hydroxystannate (ZHS) with hydrated fillers, on the fire properties of plasticised PVC and polychloroprene. It is shown that magnesium and aluminium hydroxides specially coated with ZHS, confer significantly increased combustion resistance and lower levels of smoke evolution to these polymers. This permits large reductions to additive loading relative to unmodified filler, without sacrificing flame retardant or smoke suppressant performance. 10 refs. 

The formula is C H Cl, molecular weight is 88.5, degree of polymerisation is 1000-3500 and SG is 1.20-1.25. The vulcanised forms of polychloroprene are known as neoprene . It has good resistance to heat and flames, oils, acids and ozone, which makes it useful for outdoor end-uses such as shelters, covers and industrial protective clothing. 

Uses Plasticizer for polychloroprene and other polymers resin extender, plasticizer improving water, chem., oil, and gas resist, in traffic paints, protective coatings EP agent in metalworking fluids flame retardant for resins, air filters, plasticized PVC, rubber incl. neoprene, PU, textiles, paints, adhesives... 

Polychloroprene is produced by free-radical emulsion polymerization of primarily trans-2-chloro-2-butenylene moieties. Chloroprene rubber possesses moderate oil resistance, very good weather and oil resistance, and good resistance to oxidative chemicals. Performance properties depend on compound formulation, with the polymer providing ftmda-mental properties. This is typical of any polymer and its compounds. Chloride imparts inherent self-extinguishing flame retardance. 

Fillers. Fillers are used in compounds to increase viscosity, increase solids, and to lower cost. Most fillers used in latex do not exhibit the reinforcing effect that is characteristic of their use in dry-type polychloroprene. Water-washed whiting (calcium carbonate) can be added directly to the latex. Most clays are acids and must be neutralized and slurred before adding to the latex. When used at levels ranging from 10- to 20-phr, fine clays such as DIXIE Clay (R. T. Vanderbilt Co.) can add some degree of reinforcement. Hard clays have much smaller particle size than soft clays. Feldspar can be added directly to the latex but will tend to settle quickly. Hydrated alumina is used primarily to improve flame retardancy and improve water resistance. Large-particle-size hydrated alumina can be added directly to the latex. 

Woven fabrics used for printer blankets are coated with polychloroprene to provide resistance to solvent and inks. Polychloroprene composite laminates for industrial suits (eg firefighter s suits) are coated with polychloroprene to provide chemical resistance, weather/abrasion resistance, durability, and a degree of flame retardancy. 

Polychloroprene or neoprene was one of the first synthetic rubbers available to the rubber industry. It now represents 5% of the world s consumption of rubber and is one of the more important speciality elastomers due to its resistance to lubricating oils and greases, oxygen, ozone, weathering, heat and flame. It has been the subject of continuous modification to meet changing market conditions, the main developments being, in chronological order ... 

The wide use of polychloroprene in the wire and cable industry has been due to its good balance of properties, its resistance to weathering, ozone, abrasion, flame and oil. These properties make it very suitable for use in... 

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