Catalyst epoxy resin

Borazines, particularly polymeric compounds, have been extensively investigated as preceramic materials from which coatings and fibers of boron nitride can be produced upon thermolysis. B-aryl and halogeno-amino borazines are reported to have use as fire retardants in cotton and nylon textiles. Other reported uses for borazines are as epoxy resin catalysts, polymerization inhibitors of unsaturated alcohols and esters, and catalysts for polymerization of alkenes (95). 

Cleaning products Chloroform Diesel fuel Epoxy resin catalysts Gasoline... 

Use Solvent and intermediate, curing agent for rubber and epoxy resins, catalyst for condensation reactions, ingredient in oils and fuels, complexing agent. 

Reference Epoxy Resin Catalyst Solvent Time and Temperature Inherent Viscosity 0.5 w/v % in DMF at 25°C Epoxy Equival- ent... 

Tricresyl phosphate, 2% (plasticiser in resin systems) Triethylenetetramine, 0.5% petrolatum (epoxy resin catalyst)... 

Diethylene triamine, 1% petrolatum (epoxy resin catalyst)... 

Epoxy resins, catalysts, other resins Etching chemicals, photoresists Hydrofluoric acid Fibreglass Others... 

The binder system of a plastic encapsulant consists of an epoxy resin, a hardener or curing agent, and an accelerating catalyst system. The conversion of epoxies from the Hquid (thermoplastic) state to tough, hard, thermoset soHds is accompHshed by the addition of chemically active compounds known as curing agents. Flame retardants (qv), usually in the form of halogens, are added to the epoxy resin backbone because epoxy resins are inherently flammable. 

Epoxy Resins. Polysulftdes may also be cured by reaction with epoxy resins (qv) according to the reaction in equation 2. Amines or other catalysts are used and often primary or secondary amine resins are cured together with the polysulfide. 

The production of alkylphenols exceeds 450,000 t/yr on a worldwide basis. Alkylphenols of greatest commercial importance have alkyl groups ranging in size from one to twelve carbons. The direct use of alkylphenols is limited to a few minor appUcations such as epoxy-curing catalysts and biocides. The vast majority of alkylphenols are used to synthesize derivatives which have appUcations ranging from surfactants to pharmaceuticals. The four principal markets are nonionic surfactants, phenoUc resins, polymer additives, and agrochemicals. 

High purity 4-dodecylphenol is used to produce specialty surfactants by its reaction with ethylene oxide. The low color of high purity 4-dodecylphenol is important in this appHcation from a standpoint of aesthetics. 4-Dodecylphenol is also used to produce phenoHc resins which are used in adhesive appHcations and printing inks. 4-Dodecylphenol is also used as an epoxy curing catalyst where the addition of 4-dodecylphenol accelerates curing of the epoxy resin to a hard, nontacky soHd. 

Another important use of BCl is as a Ftiedel-Crafts catalyst ia various polymerisation, alkylation, and acylation reactions, and ia other organic syntheses (see Friedel-Crafts reaction). Examples include conversion of cyclophosphasenes to polymers (81,82) polymerisation of olefins such as ethylene (75,83—88) graft polymerisation of vinyl chloride and isobutylene (89) stereospecific polymerisation of propylene (90) copolymerisation of isobutylene and styrene (91,92), and other unsaturated aromatics with maleic anhydride (93) polymerisation of norhornene (94), butadiene (95) preparation of electrically conducting epoxy resins (96), and polymers containing B and N (97) and selective demethylation of methoxy groups ortho to OH groups (98). 

Epichlorohydrin and Bisphenol A-Derived Resins. Liquid epoxy resins maybe synthesized by a two-step reaction of an excess of epichl orohydrin to bisphenol A in the presence of an alkaline catalyst. The reaction consists initially in the formation of the dichi orohydrin of bisphenol A and further reaction by dehydrohalogenation of the intermediate product with a stoichiometric quantity of alkaH. 

Advancement Process. In the advancement process, sometimes referred to as the fusion method, Hquid epoxy resin (cmde diglycidyl ether of bisphenol A) is chain-extended with bisphenol A in the presence of a catalyst to yield higher polymerized products. The advancement reaction is conducted at elevated temperatures (175—200°C) and is monitored for epoxy value and viscosity specifications. The finished product is isolated by cooling and cmshing or flaking the molten resin or by allowing it to soHdify in containers. 

In recent years, proprietary catalysts for advancement have been incorporated in precataly2ed Hquid resins. Thus only the addition of bisphenol A is needed to produce soHd epoxy resins. Use of the catalysts is claimed to provide resins free from branching which can occur in conventional fusion processes (10). Additionally, use of the catalysts results in rapid chain-extension reactions because of the high amount of heat generated in the processing. 

Polyphenols or phenol-terminated resins are utilized to effect chemical cross-linking of epoxy resins with added catalysts or accelerators for the reaction (26). 

Unless great care is taken in control of phenol/acetone ratios, reaction conditions and the use of catalysts, a number of undesirable by-products may be obtained such as the o-,p- and o-,o- isomers of bis-phenol A and certain chroman-type structures. Although tolerable when the bis-phenol A is used in epoxy resins, these have adverse effects on both physical properties and the colour of polycarbonate resins. 

The commercial interest in epoxide (epoxy) resins was first made apparent by the publication of German Patent 676117 by I G Farben in 1939 which described liquid polyepoxides. In 1943 P. Castan filed US Patent 2 324483, covering the curing of the resins with dibasic acids. This important process was subsequently exploited by the Ciba Company. A later patent of Castan covered the hardening of epoxide resins with alkaline catalysts used in the range 0.1-5% This patent, however, became of somewhat restricted value as the important amine hardeners are usually used in quantities higher than 5%. 

Hexahydrophthalic anhydride (Figure 26.10 II) (Mol. Wt. 154) has a melting point of 35-36°C and is soluble in the epoxy resin at room temperature. When 0.5% of a catalyst such as benzyldimethylamine is used the curing times are of the same order as with phthalic anhydride. About 80 phr are required. In addition... 

Arsenic compounds can be very effective corrosion inhibitors but their toxicity, ineffectiveness in hydrochloric acids above 17% active and in the presence of H S, and their ability to poison refinery catalysts has limited their use (148). Epoxy resins have been coated onto metal surfaces and cured with a polyamine to reduce corrosion (149). 

Bisphenol A-derived epoxy resins, 10 356 Bisphenol A epoxy novolacs, 10 370 Bisphenol A manufacture, microporous catalysts and, 14 420 Bisphenol A moiety, 10 355-356 Bisphenol A polycarbonate (BPA-PC),... 

Figure 2 shows STEM images of a 8%wt Pd/2%wt Pt catalyst which is supported on charcoal. The sample was prepared for microscopy by embedding in epoxy resin and sectioning with a diamond knife in an ultramicrotome, and was examined in a Vacuum Generator s Ltd HB5 STEM, with a 5A probe. The sample thickness is about 500A. 

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