Curing catalytic

Catalytic curing agents initiate resin homopolymerization, either cationic or anionic, as a consequence of using a Lewis acid or base in the curing process. The Lewis acid catalysts frequently employed are complexes of boron trifluoride with amines or ethers. 

Catalytic cracking unit, 24 258-259 Catalytic curing agents, 10 388, 411-415 Lewis acids, 10 413 Lewis bases, 10 411-413 photoinitiated, 10 414-415 Catalytic cycle(s), 5 201... 

Curing agents account for much of the potential hazard associated with use of epoxy resins. There are several major types of curing agents aliphatic amines, aromatic amines, cycloaliphatic amines, acid anhydrides, polyamides, and catalytic curing agents. The latter two types are true catalysts, in that they do not participate in the curing process. 

Curing agents lhai give the optimum in elevated temperature properties for epoxy novolaks arc (hose with good high icmperaiure performance such as aromatic amines, catalytic curing agents, phenolics. and some anhydrides... 

Previous work (5) has been limited to the glycidyl ether type epoxies, requiring catalytic curing rather than the conventional hardener type curing to facilitate formation of the desired rubbery particles. 

The catalytic curing agents commonly used include tertiary amines, Lewis acids and bases, and dicyandiamide. Since their function is truly catalytic, the catalyst is added at relatively low concentrations (0 to 5% by weight) to the epoxy formulation. Homopolymerization generally requires both the presence of catalysts and elevated temperatures for the reaction to proceed. Like the polyaddition reaction, the homopolymerization reaction is accelerated by hydroxyl groups or tertiary amines. 

Tetraglycidyl ether of tetraphenolethane is an epoxy resin that is noted for high-temperature and high-humidity resistance. It has a functionality of 3.5 and thus exhibits a very dense crosslink structure. It is useful in the preparation of high-temperature adhesives. The resin is commercially available as a solid (e.g., EPON Resin 1031, Resolution Performance Polymers). It can be crosslinked with an aromatic amine or a catalytic curing agent to induce epoxy-to-epoxy homopolymerization. High temperatures are required for these reactions to occur. 

Catalytic curing agents (e g., tertiary amines) Long pot life High heat resistance Can be used as an accelerator or as the sole curative Long elevated-temperature cure Poor moisture resistance Rigid Adhesives Electrical encapsulation Laminates Powder coatings... 

The relationship between Tg and (q(E.) has been calculated from Eq. (9) for

cured resins with different e are shown in Fig. 4. The curing agents used are DETA 25), EDA 26), and DDM 8) as a diamine, succinic acid anhydride (Sue A)21) as an acid anhydride and 2-ethy 1-4-methyl imidazole (Im) 21) as a catalytic curing agent. 

Additives and comonomers in thermoset, moisture, UV, and catalytically curing resins or coatings (e.g., acrylic, epoxy, melamine, and unsaturated polyester systems)... 

DSC measurements, the catalytic curing reaction between the thermal latent complexes I (di(l-methylimidazole)cobalt(II)dicyanate) and II (di(I-methylimi-diazole)-bis(dimethyldioximato)cobalt(III)nitrate) and epoxy resins was demonstrated to be very fast at lower temperatures compared with curing with stoichiometric quantities of 4,4 -diaminodiphenylsulfone (Figure 1) [6]. 

Process modelling of RTM polyesters was examined by Kenny et al. (1990), who identified the following (auto-catalytic) cure kinetic and (empirical Castro-Macosko (Castro and Macosko 1982) model, as highlighted in (Equation 5.8)) chemorheological models for use in their process simulation ... 

Liu et al. (2004, 2005) examined a three-dimensional non-linear coupled auto-catalytic cure kinetic model and transient-heat-transfer model solved by finite-element methods to simulate the microwave cure process for underfill materials. Temperature and conversion inside the underfill during a microwave cure process were evaluated by solving the nonlinear anisotropic heat-conduction equation including internal heat generation produced by exothermic chemical reactions. 

Tertiary amines are commonly referred to as catalytic curing agents since they induce the direct linkage of epoxy groups to one another. The reaction mechanism is believed to be as follows ... 

Polyester Paints. Binder based on unsaturated polyester resins (copolymerized with styrene), low emission of organic solvents, catalytic curing by organic peroxides or UV radiation, highly resistant to abrasion, alcohols, and other chemicals (cleaning agents). 

Catalytic-curing agents (Lewis bases and Lewis adds) 86... 

Lewis acids Catalytic cure (homopolymerization) Modified amine complex. Anchor 1040 (Air Products) 5-12 phr, fast gel time... 

---