phenol formaldehyde resin properties

phenol formaldehyde resin properties

229920001568 phenolic resins Polymers 0 claims title 8 EP82100916A 1981-02-25 1982-02-09 Curable phenol-formaldehyde resin with elastic properties after curing Expired EP0058872B1 ( en ) In an acidic medium, the reaction between the phenol-hydroxymethyl and the hydrogen atom on the phenol ring is faster than that between the aldehyde and the phenol. Such pH values, however, are obtained in the case of the usual PF-resins at a content of NaOH of 5 to 10 mass%. It has also been shown that lignocellulosic substrates have a distinct influence on the hardening behavior of PF-resins [34,35], of all the other formaldehyde-based adhesives, and of other thermosetting wood adhesives (such as isocyanates): the activation energy of the hardening process is much lower than for the resin alone [35]. Although molded products no longer represent their most important application, through their use as adhesives they still represent almost half of the total production of thermosetting polymers.…. Phenol-formaldehyde (PF) resins, commonly referred to as phenolic resins, are thermosetting plastics used in a variety of applications. Mainly for the production of moulding sands used in foundries, for the manufacture of moulding compounds, electric insulation plates used in electronics and varnishes. 1 The PF resin is a kind of synthetic polymer obtained from the reaction between phenol and formaldehyde. Alkaline PF-resins contain free-reactive methylol groups in sufficient number and can harden even without any further addition of formaldehyde, of a formaldehyde source, or of catalysts. Although they came into existence at the very start of the age of polymers, they continued to be developed into more and more applications. Phenol Formaldehyde Resin for our esteemed clients. 30. Phenol formaldehyde resins or phenolic resins are synthetic polymers obtained by the reaction of phenol or substituted phenol with formaldehyde. Also wood-inherent chemicals might have an accelerating influence on the hardening reactivity of PF-resins [91]. Procedures for the simultaneous neutralization of acid-hardened PF-glue lines during their curing have also been described [36]. Phenolic resins are the condensation products of phenol and formaldehyde and are an important class of adhesives. They are especially desirable for exterior plywood, owing to their good moisture resistance. Phenol can react with formaldehyde at the ortho and para positions, generating mono, di, and trimethylolphenol as the reaction products. The purpose of such special resins is the gluing of wet wood, where the danger of over-penetration of the resin into the wood surface can cause a starved glue line. The materials are reacted to a suitable endpoint, cooled under vacuum, and usually distilled to remove the water present from the formaldehyde solution as well as the water of condensation from the polymerization reaction. Diluting the phenol/formaldehyde resin with cyclic urea prepolymer reduces the free phenol and other volatile phenolic moiety levels of the phenol/formaldehyde resin which reduces air pollution. Phenolic resins, invariably reinforced with fibres or flakes, are also molded into insulating and heat-resistant objects such as appliance handles, distributor caps, and brake linings. A more effective PF-accelerating system is the addition of esters such as propylene carbonate [32,37–42], or even better, of glycerol triacetate (triacetin) [15,32,43] or guanidine carbonate [43]. When a stoichiometric deficiency of formaldehyde is used under acidic conditions, novolac oligomers are produced. In order to improve the properties of boron-containing phenol/formaldehyde resin, a tetrabromobisphenol A-based epoxy resin was used as curing additive. Also known as phenolic resins, phenol-formaldehyde polymers were the first completely synthetic polymers to be commercialized. 100°C. Phenol-formaldehyde resins make excellent wood adhesives for plywood and particleboard because they form chemical bonds with the phenol-like lignin component of wood. Furan binders provide many of the advantages of phenolic binders while resulting in substantially reduced VOC emissions.

Tate's Chocolate Chip Walnut Cookie Recipe, How To Write An Academic Book, Wellington, Shropshire History, Mourning Dove Life Cycle, Garnier Olia Chocolate Brown, Ford Family Net Worth 2020,



Comments are closed.