Furane adhesives

These are dark-colored synthetic thermosetting resins containing the chemical group known as the furane ring (Fig. 8.4). 

Furane resin adhesives are used as bonding agents or modifiers of other adhesive materials. Applications include surfacing and bonding agents for flooring compositions and acid-resistant tiles. 

Furane adhesives are suitable for gap-filling applications, because their strength is maintained with thick glue hues. For this reason, the resins are used as modifiers for urea-formaldehyde adhesive to improve gap-filling and craze resistance. As fiiranes are compatible with a variety of other resins, they are used in mixtures with silicates and carbonaceous materials 

---

Injecting epoxy, furan, or furan-formaldehyde resins into poorly consolidated formations to consolidate them was a common sand control practice for thin highly productive formations (44-46). Organic solvents (46) and silane coupling agents (47) are used to promote adhesion of the resin to the rock surface. Excess resin is flushed deeper into the formation to minimize resin hardening in the flow channels since this would reduce formation permeability. 

Epibond Epoxy adhesive resin Furane Plastics... 

Typical surface preparation calls for cleaning with acetone, MEK, or other common solvent. Once clean, the substrate is then mechanically abraded with sand, grit or vapor blast, or steel wool. The surface is again wiped clean with fresh solvent. Typical adhesives that are employed include epoxies, urethanes, and cyanoacrylates. Polysulfides, furanes, and polyester adhesives have also been suggested. 

Carbohydrate-based adhesives, in which the formulation begins with the carbohydrate, have been reported (130), but the acid system used during formulation readily degrades the original carbohydrate to furan intermediates that... 

Furfural (1), derived from annually renewable agricultural byproducts, is an important industrial chemical manufactured and used throughout the world. It is the feedstock for a number of derivative chemicals generically known as furans -the structural characteristic of which is the five-membered oxygen-containing heterocyclic ring. Furfuryl alcohol (2) is the most important derivative of commerce, where it is used primarily in synthesis of adhesive polymers. 

All of the studies mentioned are directed to lignins derived from pulp and paper manufacture. This requires that a traditionally conservative pulp and paper industry embark on further development as a chemical producer. However, Helena Chum and her colleagues (Chapter 11) derive their phenolics from lignin by fast pyrolysis of wood rather than as byproducts from the pulp and paper industry. Opportunities might be better for development of adhesives from a chemical manufacturer drawing on waste wood as a raw material much the same as has developed in the production of furan resins derived from agricultural residues described by Bill McKillip (Chapter 29). 

A number of very reactive compounds can be obtained from carbohydrates. Furfural, a furan, is one such compound that is produced by reacting a pentose carbohydrate under acidic conditions. Bill McKillip (Chapter 29) gives an excellent overview of furan resin chemistry and the use of furans for the production of polymeric materials such as adhesives. Furans, in particular furfural,... 

Doherty (3), Lin (4), and Hagmann (5) prepared a4(31 and a4(37 integrin antagonists consisting of V-arylsulfonyl-prolines, (III), V-arylsulfonyl aza-bicyclics, (IV), and furanic acid derivatives, (V), respectively, which were effective in treating inflammatory and adhesion pathologies. 

Furfural 69, which can be manufactured from hardwood waste, is used for the manufacturing of a furfural-acetone monomer <2000MI15>. This monomer is then used to obtain furfural resins which are suitable as binders for the production of particleboards. In a further application, these furan resins of low toxicity have been used as adhesives in the manufacture of plywood <1999MI24>. The use of such resins is recommended as it leads to products with advantageous economic and ecological indicators. The result is plywood with good physiomechanical properties when the Monomer furfuryl alcohol (FA) was used as the adhesive. 

Quarry Tile Tile is used in much of the food process and food preparation areas, also toilet and change areas. In general, it is installed without an asphaltic membrane but with a thin adhesive membrane usually an epoxy type. As noted above, the concrete substrate must be true to line without irregularities such as humps and bumps. All such flaws will telegraph through to the finished surface. Cleanliness is a major attribute of the quarry tile installation. For example, in a synthetic elastomer plant the raw latex when spilled stuck tightly to the concrete floors. Quarry tile was used with an epoxy bed and a furan joint (very narrow, Vie"). Due to the greater density of the quarry tile the unvulcanized material cleaned up easily. 

Urea-Formaldehyde Adhesives used are epoxies, nitrile-phenolics, phenol-formaldehyde, resorcinol-formaldehyde, furan, polyesters, butadiene-nitrile rubber, neoprene, cyanoacrylate, and phenolic-polyvinyl butyral (1). 

Highly diffusive penetration of SPC can be drastically lowered by active additives that are capable of raising SPC density, and, therefore, its corrosion resistance. As indicated previously, the most effective results were obtained by introduction of FA or TFS additives. Addition of monomeric additives to silicate composition improves the physical-mechanical characteristics and chemical resistance of silicate compositions due to improvement in the quality of silicate bonds and better adhesion between the binder and coarse filler [1], In other words, the influence of the monomeric additives is conditioned by consolidation of liquid glass gel during hardening and modifications of alkaline components due to inoculation of furan radicals. 

Benzo[Z ]furan, a colourless, oily, water-insoluble liquid, bp 173°C, occurs in coal tar. It is probably formed during coal carbonization by cyclodehydration of 2-ethylphenol. Copolymerization of indene in the presence of Bronsted or Lewis acids yields the so-called coumarone resins, which find use in industry (adhesives, paints, binders). 

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.)... 

Compounds 1, 2, and 3 are among the most relevant monomers or co-monomers for furan-based adhesives, but so also are furfurylidene acetone (5) and its bis-adduct 6. The synthesis of 5 involves the base-catalyzed reaction between 1 and acetone [2] and, in the same context, the use of an excess of 1 leads to the formation of 6 ... 

This chapter is devoted to adhesives and resins prepared from totally furanic monomers or formulations in which furanic compounds are added. In this realm, only... 

Table 1 Properties of Furanic Compounds Used in Adhesives...

III. HISTORY, ADVANTAGES, AND LIMITATIONS ASSOCIATED WITH THE USE OF FURAN-BASED ADHESIVES... 

The first synthetic thermosets used as adhesives were phenol-formaldehyde resins produced at the end of the nineteenth eentury, historically linked to Baekeland s process which attained industrial status at the beginning of the twentieth century [4], Furanic condensates appeared mueh later as a result of the marketing of 2. They were first used as foundry binders by Quaker Oats in 1960. The use of furanic resins in the aerospace industry began ten years later. Although furanic resins represent a mere 1 % of the total thermoset produetion, the high added-value of these materials amply justifies their use. In fact, furan-based adhesives and binders are fire-, solvent-, and acid- or alkali-resistant. They are known, however, to display two main drawbacks related to their sensitivity to shrinkage and oxidation. 

Regardless of the fact that numerous investigations exist about the possibility of incorporating the furan heterocycle into wood adhesive formulations, their industrial exploitation is still modest. The first suggestion concerning the use of 1 in partial substitution of formaldehyde in phenolic resins was put forward in 1958 by Baxter and Redfern [18] who proposed that the furfural units were incorporated into the polymer skeleton following condensation reactions such as ... 

Poly(hydroxymethyl furfurylidene-acetone) adhesive resins were synthesized and characterized [68-70] through the 5-formaldehyde adduct (19) and its acid-catalyzed polymerization. The catalysts used were sulfuric, phosphoric, or p-toluenesulfonic acid. The authors postulated that the first condensation products resulted from the condensation of two methylol groups of two 19 molecules (adduct 20). They also proposed a hypothetical structure of the network formed after curing (21). It seems, however, difficult to envisage the acid-catalyzed resinification of 19 without the participation of hydrogen atoms at the C5 position of the furanic ring [2]. 

Bowles et al. [72] studied the copolymerization of different methacrylates with NCO-ethyl methacrylate to obtain dental adhesives. Furfuryl methacrylate (23) was among the monomers tested. The main objective of this investigation was to establish a correlation between the solubility parameter of the copolymers and their shear strength. It was moreover shown that the setting time of the furan-based copolymer was very short compared to that of aliphatic homologues, but its shear strength was relatively low. 

---