Resorcinol-formaldehyde resins production

A second type of urethane adhesive is currently being introduced to the U.S. construction industry. The adhesive was originally developed in Japan. The system is two component. The isocyanate component is a modified polymeric MDI. The cross-linkable component contains water with water-soluble or water-emulsifiable resins. The adhesive produces strong, water-resistant bonds and has shown promise as a possible lower cost substitute for resorcinol formaldehyde resins in the adhesion of laminated beams. The product is now being used in Japan to bond wood and various other porous substrates at the rate of about 10 million pounds per year. The first U.S. application of the product has been the bonding of wood doors. The opportunities for products of this type should be excellent in view of the ever-increasing governmental pressures on solvents. 

Resorcinol-formaldehyde resins are cold-setting adhesives for wood structures. Urea-formaldehyde adhesives, commonly modified with melamine formaldehyde, are used in the production of plywood and in wood veneering for interior applications. Phenol-form-aldehyde and resorcinol-formaldehyde adhesive systems have the best heat and weather resistance. 

An RFL dip consists of an aqueous resorcinol formaldehyde resin liquid with a ruhher latex. The RF resin is used to achieve good adhesion to the organic fiber substrate whether it be rayon, nylon, or polyester. The rubber latex portion can be a natural rubber latex or a styrene butadiene vinylpyridine (terpolymer) latex or even a neoprene latex. This rubber latex is present to achieve good adhesion with the rubber matrix itself. So the RFL allows good adhesion between the rubber and the textile cord reinforcement whether it is used in the manufacture of passenger tires, truck tires, off-the-road tires, power transmission belts, V-belts, timing belts, or various hose products. 

Resorcinol formaldehyde resins used to prepare RFL dips are the product of a chemical reaction between resorcinol and formaldehyde (or formalin) as shown in Figure 5.21. 

Figure 5.32 Production of the resorcinol formaldehyde resins from a reaction between resorcinol and formaldehyde...

Resorcinol-Formaldehyde Resins (Moult, 1977 Dick, 1987) - Resorcinol adhesives are eondensation products of resorcinol with formaldehyde or various phenol-formaldehyde resoles. Most of the adhesives manufaetured are of the second type due to their lower cost. Resorcinol is much more reactive with formaldehyde dian phenol since it has two meta hydroxyl groups. The two groups reinforce eaeh other in their activation of the ortho and para positions of the benzene ring. To make stable resorcinol/formaldehyde resins which do not gel on aging, 0.5 to 0.7 moles of formaldehyde is added per mole of resorcinol. At the time of use, some additional formaldehyde is added and... 

It is worthwhile to review the U.S. market size for the four principal resins currently used in wood-panel products today (4 )- These are phenol-formaldehyde (PF), urea-formaldehyde (UF), melamine-formaldehyde (MF), and resorcinol-formaldehyde (RF) (Table III). When these production figures are compared to the quantities of lignin potentially available (Table II), it is immediately obvious that all wood adhesives could be replaced by only a very small fraction of the lignin produced annually during chemical woodpulping processes. 

After EA evaporation, a novolak formulation with 50% phenol and 50% of the P/N fraction was successfully prepared. Gel times for the P/N fractions suitably prepared are intermediate between resorcinol and traditional phenol-formaldehyde resins. Preliminary projected amortized production costs for the P/N fraction are 10(16) cents per pound for a 1,000(250) tons per day plant ( 10/dry ton feedstock,... 

A wood-based composite can be defined as a composite material mainly composed of wood elements. These wood elements are usually bonded together by a thermosetting adhesive (wood truss products could also be regarded as wood-based composites, but connected by metal connectors). The commonly used adhesives include urea-based adhesive (such as urea formaldehyde resin), phenolic-based adhesive (including phenol resorcinol adhesives), isocyanate-based adhesive, and adhesives from renewable resources (like soybean, lignin etc). The wood elements in wood composites can be in many different forms such as ... 

The earliest wood adhesive for mass produetion of panels was phenol formaldehyde (PF). This is widely used for products designed to perform in severe weathering eonditions and dominates the exterior plywood market. Resorcinol formaldehyde is a somewhat similar resin system that cures at ambient temperatures, but the cost is much higher, limiting its use in high-volume applications. These systems, although formaldehyde-based, do not have the continuing formaldehyde emission problem that is associated with other formaldehyde-based systems. 

At one time urea-formaldehyde was used extensively in the manufacture of plywood but the product is today less important than heretofore. For this purpose a resin (typically U-F molar ratio 1 1.8)-hardener mixture is coated on to wood veneers which are plied together and pressed at 95-110°C under pressure at 200-800 Ibf/in (1.38-5.52 MPa). U-F resin-bonded plywood is suitable for indoor application but is generally unsuitable for outdoor work where phenol-formaldehyde, resorcinol-formaldehyde or melamine modified resins are more suitable. 

Platinum nanoparticles/ nanoporous carbons composites have been synthesized from mixtures of Pt complex salts, surfactants and a resorcinol-formaldehyde (RE) resin. The composite has high BET surface area and large micropore and mesopore volume because of gas generation from surfactant molecules. The product has well-dispersed small Pt particles with a diameter of... 

Cycleweld metal adhesives (Saunders-Chrysler Co.) Resorcinol-formaldehyde adhesives (Penn. Coal Products Co.) Metal-bond adhesives (Havens, Consolidated Vultee-Aircraft Corp.) Furane resin adhesives (Delmonte, Plastics Inst.) and Pliobond (Goodyear Tire and Rubber Co.)... 

Phenol-formaldehyde resin is the most common adhesive for exterior applications due to its water resistance, low initial viscosity and its ability to bond various types of wood substrates [1], Because of its resemblance to phenolic moieties, studies on tannin have been oriented towards an alternative formulation to replace the current synthetic phenol-formaldehyde or phenol-resorcinol-formaldehyde adhesives [2-4], A few suitable alternative natural resources such as oil palm shell, pecan shell nut, lignin, starch, rice bran and tannin are also available for this purpose. Among these materials, tannins represent the best immediate substitute for phenol in wood adhesive production [1],... 

Rubber products such as tyres, belts and hose rely on reinforcement by textiles to achieve the required physical properties. To effect reinforcement, textile and rubber must be adequately bonded together, and to promote adhesion, there is a range of treatments to suit most fibre-rubber systems. The adhesion-promoting material (dip) is usually a terpolymer latex of butadiene-styrene-vinyl pyridine (or a blend of SBR and vinyl pyridine), which bonds well to the fibres, together with a resorcinol formaldehyde precondensate, which, on curing, bonds well to mbber a three-dimensional resin network is formed. 

A wide range of adhesive types and chemistries are used to bond wood elements to one another (Table 2), but relatively few adhesive types are utilized to form the composites themselves. The vast majority of pressed-wood products use synthetic thermosetting adhesives. In North America the most important wood adhesives are the amino resins (qv), eg, urea-formaldehyde (UF) and melamine-formaldehyde (MF), which account for 60% by volume of adhesives used in wood composite products, followed by the phenolic resins (qv) eg, phenol-formaldehyde (PF) and resorcinol-formaldehyde (RF), which account for 32% of wood composite adhesives (12,13). The remaining 9% consists of cross-linked vinyl (X-PVAc) compounds, thermoplastic poly(vinyl acetates) (PVA), soy-modified casein, and polymeric diphenylmethylene diisocyanate (pMDI). Some products may use various combinations of these adhesives to balance cost with performance. 

Some other reported curing agents are quinone [81], chloranil [81], anhydroformaldehyde aniline [82], methylolureas and melamines [83], ethylenediamine-formaldehyde products, and paraformaldehyde. Resorcinol novolac resins can be cured with paraformaldehyde [84] and the mildly acid nature of resorcinol helps to catalyze the curing reaction [84]. Ammonium salts have also been reported as accelerators for the curing of phenolic resins [85]. 

Benzene is used as a feedstock to produce resorcinol, a very important chemical that is used to manufacture resorcinol formaldehyde (RE) resin for RFL dips for tire cord adhesion, as well as RF resin for HRH adhesion systems for rubber-to-metal adhesion, and for the production of TIER for curing polyurethane rubber. 

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. 

Uses. Furfuryl alcohol is widely used as a monomer in manufacturing furfuryl alcohol resins, and as a reactive solvent in a variety of synthetic resins and appHcations. Resins derived from furfuryl alcohol are the most important appHcation for furfuryl alcohol in both utihty and volume. The final cross-linked products display outstanding chemical, thermal, and mechanical properties. They are also heat-stable and remarkably resistant to acids, alkaUes, and solvents. Many commercial resins of various compositions and properties have been prepared by polymerization of furfuryl alcohol and other co-reactants such as furfural, formaldehyde, glyoxal, resorcinol, phenoHc compounds and urea. In 1992, domestic furfuryl alcohol consumption was estimated at 47 million pounds (38). 

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