Epoxy-phenolic finishes

Epoxy-phenolic finishes are among the most chemically resistant known. 20-30 per cent phenolic resin is used with epoxy resin of molecular weight 1400 and the stoving schedule is 20 min at 180-205° C. Phenolic resins alone give excellent chemical resistance, but cross-linking with epoxy resin improves adhesion and impact resistance. The poor colour of the coatings is due to the phenolic resin. The... 

System B. Epoxy Phenolic Primer/Epoxy Phenolic Finish/Epoxy Phenolic Finish... 

The rate of stripping or the stripabiUty on cataly2ed urethane and epoxy resin finishes can be increased by adding formic acid, acetic acid, and phenol. Sodium hydroxide, potassium hydroxide, and trisodium phosphate [10101-89-0] may be added to the formula to increase the stripabiUty on enamel and latex paints. Other activators include oleic acid [112-80-17, trichloroacetic acid [76-85-9], ammonia, triethanolamine [102-71-6], and monoethyl amine. Methylene chloride-type removers are unique in their abiUty to accept cosolvents and activators that allow the solution to be neutral, alkaline, or acidic. This abihty gready expands the number of coatings that can be removed with methylene chloride removers. 

RTM is compatible with a variety of thermosetting polymers including polyester, vinyl ester, epoxy, phenolic, modified acrylic, and hybrid polyester-urethane. A convenient typical viscosity of thermoset precursors is in the range of 0.2-0.6 Pa s. The RTM process has the following advantages (i) emissions are lower than in open-mold processes such as spray-up or hand lay-up (ii) it can produce parts faster, as much as 5-20 times faster than open-mold techniques (iii) the mold surface can produce a high quality finish (iv) complex mold shapes can be achieved and... 

These intermediates are too small to be used alone, but need to be enlarged and modified to obtain compatibility with other resins. In the case of the phenol formaldehyde resins this is achieved by either using para-substituted phenols where the substituent contains at least four carbon atoms or by reacting the intermediate with the natural resin, rosin, and then esterifying with glycerol or pentaerythritol. These resins have a limited use in stoved epoxy finishes where colour is not an important factor. 

The characteristics of the three most common thermoset resin systems used in pultrusion are compiled in Table 11.2 [3]. It is noteworthy that unreinforced polyesters and vinylesters shrink 7-9% upon crosslinking, whereas epoxies shrink much less and tend to adhere to the die. These epoxy characteristics translate into processing difficulties, reduced processing speed, and inferior component surface finish. It is normal practice to use resin additives to improve processability, mechanical properties, electrical properties, shrinkage, environmental resistance, temperature tolerance, fire tolerance, color, cost, and volatile evaporation. It is normally the resin, or rather its reactivity, that determines the pulling speed. Typical pulling speeds for polyesters tend to be on the order of 10-20 mm/s, whereas speeds may exceed lOOmm/s under certain circumstances. Apart from the resins characterized in Table 11.2, several other thermosets, such as phenolics, acrylics, and polyurethanes, have been tried, as have several thermoplastics (as will be discussed in Sec. 11.2.6). 

Phenolic epoxy tank lining primer/intermediate and finish formulations 66 100 2 h 24 h Two components, good resistance to chemicals and higher temperatures... 

In many cases the use of epoxy materials in so-called field conditions (for industrial, construction sites, etc.) demand an increase in the reaction velocity, which is usually achieved by adding accelerators. At present, the widely used accelerators include alkyl-substituted phenols, benzyl alcohol, carboxylic acids (in particular, salicylic acid), and others. A major disadvantage of these accelerators is their tendency to migrate from the cured epoxy matrix during the exploitation, which could lead to a change in the physical properties of the polymer. They also act as a plasticizer of epoxy-based polymers, and as a result reduce the polymer s chemical resistance. Thus, there is a need for new accelerator-modifiers that can provide faster curing of epoxy-amine compositions without negative side effects, and also improve the properties of the finished product. 

CAS 58160-99-9 EINECS/ELINCS 261-145-5 Uses Adhesion promoter for water-sol./water-disp. resins incl. vinyl and acrylic latexes, epoxies, and phenolic binder dispersions for sealants, adhesives, coatings, insulation binders finish forwoven fiberglass filler treatments coupling agent for glass fiber sizes Properties Lt. straw clear liq. sol. in water insol. in toluene, ethyl ether, CCL reacts with acetone sp.gr. 1.076 vise. 4 cSt flash pt. (PMCC) > 66 C... 

Uses Adhesion promoter for filled and reinforced resins (urethanes, epoxies, acrylates, phenolics), adhesives, sealants, coatings, glass fiber sizes and finishes, primers, and foundry sand binders Features Improves high-temp, resist., increases stability of resin/silane bond at high temps. 

Chem. Descrip. y-Ureidopropyltrimethoxysilane CAS 23843-64-3 EINECS/ELINCS 245-904-8 Uses Adhesion promoter aiding bond between fillers and reinforcements (e.g., fiberglass, particulates, metals) and various polymers (phenolic, urea-melamine, epoxies, polyamide, PU), for use in glass fiber sizes and finishes, wool insulation resin binders, primers, foundry sand binders, adhesives, sealants, and abrasive grinding wheel binders Features Contains no flamm. or combustible solv. low VOC emissions Properties Lt. straw clear liq. sol. in methanol, ethanol, acetone, toluene, methyl Cellosolve, water m.w. 220 sp.gr. 1.15 b.p. 217-250 C (700 mm Hg) flash pt. (TCC) 99 C ref. index 1.386 100% act. Silquest Y-11597 [OSi Spec.]... 

Uses Adhesion promoter aiding bond between fillers and reinforcements (e.g., fiberglass, particulates, metals) and various polymers (phenolic, urea-melamine, epoxies, polyamide, PU) used in glass fiber sizes and finishes, wool insulation resin binders, primers, foundry sand binders, adhesives, sealants, and abrasive grinding wheel binders low VOC emissions... 

The main use for phenolic resins is in oleoresinous varnishes. Apart from the chemical-resistant finishes produced with epoxy resins (Chapter 14), other outlets include modification of alkyds to improve resistance to water and alkali, combination with U/F resins (Chapter 13) to provide metal coatings and combination with polyvinyl formal or butyral resins to produce wire enamels. 

Uses Reactant for PU, epoxy, polyester, and phenolic systems reactive additive for PU leather finishes reactive internal lubricant for polyester fiber melt spinning surfactant blend agent... 

Thermosets are highly cross-linked substances. Cross-linking occurs simultaneously with or after the formation of the finished shape. After this cross-linking or curing, the material cannot be reshaped by heating alone. Because they are highly cross-linked, thermosets are dimensionally stable up to elevated temperatures. Typical thermosets are, e.g., phenolic, urea, melamine, and epoxy resins. 

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