Resorcinol resins

Nitrile rubber is compatible with phenol-formaldehyde resins, resorcinol-formaldehyde resins, vinyl chloride resins, alkyd resins, coumarone-indene resins, chlorinated rubber, epoxies and other resins, forming compositions which can be cured providing excellent adhesives of high strength, high oil resistance and high resilience. On the other hand, NBR adhesives are compatible with polar adherends such as fibres, textiles, paper and wood. Specific formulations of NBR adhesives can be found in [12]. 

The same chemical mechanisms and driving forces presented for phenol-formaldehyde resins apply to resorcinol resins. Resorcinol reacts readily with formaldehyde to produce resins (Fig. 2) which harden at ambient temperatures if formaldehyde is added. The initial condensation reaction, in which A-stage liquid resins are formed, leads to the formation of linear condensates only when the resorcinol/formaldehyde molar ratio is approximately 1 1 [119]. This reflects the reactivity of the two main reactive sites (positions 4 and 6) of resorcinol [120]. However, reaction with the remaining reactive but sterically hindered site (2-positiori) between the hydroxyl functions also occurs [119]. In relation to the weights of resorcinol-formaldehyde condensates which are isolated and on a molar basis, the proportion of 4- plus 6-linkages relative to 2-linkages is 10.5 1. However, it must be noted that the first-mentioned pair represents two condensa-... 

Figure 3. Phenol-formaldehyde resin resorcinol separator (SEM)...

Polyethylene separators offer the best balanced property spectrum excellent mechanical and chemical stability as well as good values for acid availability and electrical resistance have established their breakthrough to be the leading traction battery separator. Rubber separators, phenolic resin-resorcinol separators, and mi-croporous PVC separators are more difficult to handle than polyethylene separators their lack of flexibility does not allow folding into sleeves or use in a meandering assembly in addition they are more expensive. 

Phenol-Formaldehyde Resin Resorcinol Separators (DARAK 2000/5005)... 

Table 12 shows the physicochemical data of separators used in open stationary batteries. Since the emphasis is on low acid displacement, low electrical resistance, and high chemical stability, the phenolic resin-resorcinol separator is understandably the preferred system, even though polyethylene separators, especially at low backweb, are frequently used. For large electrode spacing and consequently high separation thickness, microporous as well as sintered... 

A PF resol is prepared which constitutes the resin. Resorcinol chemicals or RF novolaks, in aqueous or water-alcohol solutions, are used as hardeners according to the scheme in Formula 8. 

Resorcinol-formaldehyde latex. See Resorcinol-formaldehyde resin Resorcinol-formaldehyde resin CAS 65876-95-1 24969-11-7 Synonyms Resorcinol-formaldehyde latex Resorcinol resin... 

Polyhydroxymethyl compounds phenol-formaldehyde resins, also in combination with poly(vinyl formal) resins, nitrile rubber or epoxy resins (as adhesive film), urea-fprmaldehyde resins, melamine - formaldehyde resins, resorcinol - formaldehyde resins. Uses wood (plywood manufacture), metals. 

Special applications are often governed by different priorities as already discussed in relation to golf carts, the low water loss and the delay in antimony poisoning in heavy-duty service of a forklift are of eminent importance, with the result that rubber separators remain the preferred product there. Submarine batteries offer a different picture the number of cycles to be reached is far lower ( 500) and, due to the slow ( 100h) but very deep discharge, the acid availability becomes the decisive criterion, which favors, for example, the phenolic resin-resorcinol separator. Such requirements are already similar to the application in open stationary cells. 

Phenol-Formaldehyde Resin-Resorcinol Separators (DARAK 2000/ 5005) The production process and the principal properties of this system have been described in detail in the section on traction battery separators (see Section 11.2.3.1). The outstanding properties, such as excellent porosity (70%) and resulting very low acid displacement and electrical resistance, come into full effect when applied in open stationary batteries. Due to the good inherent stiffness the backweb may even be reduced to 0.4 mm, reducing acid displacement and electrical resistance to low levels that are not achievable by any other system. Furthermore, the phenolic resin-resorcinol separator neither generates any harmful substances nor is it attacked chemically or by oxidation. The sum of these properties has made it the preferred separator for open stationary batteries. 

Materials that can be used as main components of thermosetting adhesives are urea resin, melamine resin, phenolic resin, resorcinol resin, epoxy resin, structural acrylic resin, polyester, polyurethane, polyimide, polybenzimidazole, etc. 

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