Neoprene rubber-based adhesives

The elastomers considered in this section have been selected considering the most commonly used in rubber base adhesives natural rubber butyl nibber and polyisobutylenes styrene-butadiene rubber nitrile rubber polychloroprene rubber (neoprene). Typical properties of these rubbers are shown in Table 2. 

Adhesives used to bond acetal homopolymer to itself and to other materials, such as aluminum, steel, natural rubber, neoprene rubber, and Buna rubber, include polyester with isocyanate curing agent, rubber-based adhesives, phenolics, epoxies, modified epoxies, and vinyls. Solvent cementing... 

Polychloroprene mbber (CR), often called by the trade name Neoprene, possesses the characteristics of natural robber and has the advantage of higher polarity. CR adhesives are by far the most important family of Rubber-based adhesives. 

Several elastomers can be used in rubber-based adhesives. The elastomer provides the backbone of the adhesive, so the main performance of the adhesive is provided by the rubber properties. However, several specific properties for application are imparted by adding other ingredients in the formulations. The most common elastomers used in rubber-based adhesives are natural rubber (NR), butyl rubber (BR) and polyisobutylenes, styrene-butadiene rubber (SBR), nitrile rubber (NBR) and polychloroprene rubber Neoprene) (CR). 

Then the width of the stream depends on the type of adhesive low viscosity water-based adhesives will give a 50 cm width while rubber-based adhesives, such as neoprene adhesives, may give oidy 30 to 45 cm width. It also depends on the viscosity the more fluid the adhesive, the easier it will be to spray it in fine particles. 

The major emulsion processes include the copolymerization of styrene and butadiene to form SBR rubber, polymerization of chloroprene (Fig. t -4) to produce neoprene rubbers, and the synthesis of latex paints and adhesives based mainly on vinyl acetate and acrylic copolymers. The product is either used directly in emulsion form as a paint or else the surfactants used in the polymerization are left in the final, coagulated rubber product. 

Non-structural adhesives used on CELCXDN arc usually one-component, room-temperature-curing systems based either on thermoplastic resins or elastomeric materials dispersed in solvents. They are normally used in applications which will not be exposed to temperatures over 180°F. Neoprene rubber adhesives are examples. (7). 

Although the polyurethanes form useful adhesive bonds, particularly between metals and elastomers, their use in the aerospace industry for bonding purposes is limited. Because polyurethanes tend to depolymerize above 120 °C and are subject to hydrolysis, and because aromatic urethanes autoxidize when exposed to thermal or UV light (13). epoxies are the preferred bonding material. Recently they were studied as launch seals for both land and sea missile launch tubes and were found to be superior to seals based on neoprene rubber (14). The chemical reaction for this application is proposed to be that between isocyanates and amines (Reaction 3). 

Synthetic rubber, a dimethylbutadiene, was developed as a substitute for natural rubber in Germany during World War I and saw limited use as an adhesive. In the early 1930s, neoprene rubber (then called Duprene) became available to adhesive manufacturers in the United States, and shortly thereafter in Great Britain. Today, neoprene rubber adhesives are available as both thermoplastic and cross-linking systems in both solvent and emulsion formulations. Neoprene rubber is the major base resin for contact adhesives. A limited amount of neoprene rubber is also used in sealants. 

Uses Tackifier resin for water-based adhesives and sealants based on acrylic, S/B, nat. rubber, neoprene, and PVAc, esp. for pressure-sensitive adhesives, and for coatings Features Solv.-free... 

Midgley, C.A. and Rea, J.R., Styrene-butadiene rubber adhesives. In Skeist, I. (Ed.), Handbook of Adhesives, 3rd edn. Van Nostrand Reinhold, New York, 1990, pp. 227-234. Guggenberger, S.K., Neoprene (polychloroprene)-based solvent and latex adhesives. In Skeist, 1. (Ed.), Handbook of Adhesives, 3rd edn. Van Nostrand Reinhold, New York, 1990. 

In the hot-melt type, two principal polymer types are used polyolefin and ethylene co-polymer based and polyester and polyamide type. In the solvent-based type, the most prominent are neoprene (polychloroprene)-based solvent and latex types, and polyvinyl acetate emulsions. For pressure-sensitive adhesives, the most favored are acrylic adhesives and butyl rubber/polyisobutylene types. 

Phenylene oxide-based resins (Noryl ) epoxy, polyisocyanate, polyvinyl butyral, nitrile rubber, neoprene rubber, polyurethane rubber, polyvinyUdene chloride, and acrylic. Polyethylene-nitrile rubber, polyisobutylene rubber, flexible epoxy, nitrile-phenolic, and water-based (emulsion) adhesives. Polystyrene for these foams (expanded polystyrene (EPS)), aromatic solvent adhesives (e.g., toluol) can cause collapse of the foam cell walls. For this reason, it is advisable to use either 100% solids adhesives or water-based adhesives based on SBR or polyvinyl acetate. Specific adhesives recommended include urea-formaldehyde, epoxy, polyester-isocyanate, polyvinyl acetate, vinyl chloride-vinyl acetate copolymer, and reclaim rubber. Polystyrene foam can be bonded satisfactorily with any of the following general adhesive types ... 

Table 5.3 Neoprene-based adhesive solution for bonding thin vulcanised rubber pieces ...

Adhesives are based on various polymers which have very different behaviors when submitted to heat. All adhesives will soften when the temperature reaches their softening point, but some adhesives will start to soften at 60°C such as the thermoplastic adhesives (vinyls, EVA hot melts), others at 70-80°C (neoprene and rubber based) the thermosetting adhesives will not soften until 90-150°C. 

Floor coverings - Wooden floors are glued to plywood subflooring using SBR, natural rubber and neoprene based adhesives. PVC plastie floor tiles use acrylate and nonvulcanized natural rubber adhesives. 

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