Zoldine ZT-55 5-Hydroxymethyl-1-aza-3,7-dioxabicyclo [3,3,0] octane 6542-37-6 Dow Chemical-Angus Crosslinking / Coupling / Curing Agents Aminoplaste & Phenoplastes (UF, MUF...) ADHESIVE Hardener for Resorcinol and Tannin Based Wood Bonding Adhesives. ZOLDINE ZT-55 is a low viscosity liquid that is easy and relatively safe to handle. Because of its low viscosity, ZOLDINE ZT-55 mixes readily with other hardener ingredients, producing uniform mixtures. Since the hardener viscosity will typically be low, it may be necessary to add a thickening agent such as carboxymethylcellulose to achieve the desired mix stability and adhesive application viscosity. This is particularly true for ZOLDINE ZT-55 hardeners intended for ambient cure adhesives. In this case, ZOLDINE ZT-55 hardener may require incorporation of a solid filler such as nut shell flour. The filler will precipitate unless a thickening agent is added. In any case, ZOLDINE ZT-55 hardeners mix easily with resin, and this is especially important in fast curing adhesives. These systems may utilize static mixers, and components that are easily mixed are desirable. Another advantage of ZOLDINE ZT-55 hardeners is that all of the oxazolidine is immediately available for reaction with resin. Para hardeners, on the other hand, are sometimes mixed on-site to avoid precipitation and nonuniformity that can occur upon storage. If the para mix does not set long enough, hydrolysis may be incomplete and not all of the formaldehyde will be available for reaction with resin. The on-site mixing is also inconvenient, and presents safety hazards as already discussed. ZOLDINE ZT-55 can be used as a hardener for resorcinol resin adhesives in the manufacturing of articles such as I-beams (I-joists), laminated beams (glulams), and other engineered wood products. ZOLDINE ZT-55 has achieved commercial success in oven-cure adhesive systems, and has been shown capable of meeting performance requirements (wet delamination, etc.) for ambient cure adhesives as well. ANGUS oxazolidines are saturated heterocyclic compounds prepared by reacting ANGUS primary amino alcohols with formaldehyde. Monocyclic or bicyclic oxazolidine ring structures are formed depending on the choice of starting materials. It is therefore possible to synthesize a variety of oxazolidines from ANGUS amino alcohols. ANGUS oxazolidines are highly useful materials for a wide variety of applications. Chemically, they behave as both an aldehyde and as an amine.1 ANGUS oxazolidines can be utilized as alkalinity modifiers, corrosion inhibitors or emulsifiers in formulated products.They can additionally be employed as curing agents or reactive diluents in the production of either acid or alkaline catalyzed polymers. The applications discussed herein merely highlight some of the many uses of ANGUS oxazolidines and should not be considered all-inclusive. Urea- and Melamine-Formaldehyde Resins ANGUS oxazolidines react readily with urea or melamine to form specialty adhesive resins. ANGUS oxazolidines can be used to modify the functional properties of an established urea-formaldehyde or melamine-formaldehyde condensate resin. They also can be used as raw materials in the synthesis of new resins. When utilized as curing agents for these compounds, ANGUS oxazolidines tend to impart greater flexibility and elongation characteristics to the finished product. Resins made from ANGUS oxazolidines and urea have been reported to provide improved solvent resistance. The choice of ANGUS oxazolidine also makes a significant difference in the reactivity or pot life of a given resin formula. Zoldine AT-55 tends to be the least reactive. Phenol/Resorcinol Resins ANGUS oxazolidines will react readily with most phenolic compounds. Resorcinol has been shown to be the most reactive, followed by Bisphenol A, both of which will react at ambient temperatures. Phenol itself is the least reactive with ANGUS oxazolidines, generally requiring elevated temperatures for useful reaction rates. Blends of various phenols will give intermediate rates of reaction. Reactivity is also affected significantly by the choice of oxazolidine Zoldine ZT-55 has low reactivity. Paraformaldehyde is commonly used as a hardener for phenol-resorcinol-formaldehyde (PRF) and resorcinolformaldehyde (RF) adhesive resins. The use of paraformaldehyde brings with it numerous safety issues including transportation, storage, handling, and environmental emissions. Formaldehyde exposure and emissions are closely monitored by both OSHA and the EPA. Paraformaldehyde hardener slurries are also burdened with a limited shelf life due to settling, such that they often need to be prepared just prior to use; this is often inconvenient and labor intensive. ANGUS oxazolidines are liquids which are stable, easy to handle, and contain less than 0.1% free formaldehyde. As a result, ANGUS oxazolidines are more attractive than paraformaldehyde from handling, exposure, and emission standpoints. Benefits of oxazolidine-based hardeners in PRF and RF resins include: Ease of handling (liquid; not dusty) Less than 0.1% free formaldehyde Lower formaldehyde emissions during cure (versus para) Adjustable cure response including oven, room temperature, and sub-ambient cure capabilities As discussed above, reactivity with a given PRF or RF resin is affected significantly by the choice of oxazolidine. The cure response of a given oxazolidine can be adjusted with the addition of strong bases, lower alcohols and glycols, and alkyhydroxylamines such as N-Isopropytheydroxylamine (IPHA). These materials will slow the reaction of oxazolidines with resin systems. Applications of oxazolidine hardeners with resorcinolcontaining resins include woodbonding adhesives, tire cord adhesives,refractory bricks and resorcinol modified starch adhesives. Phenolic Novolac Resins ANGUS oxazolidines can also be used as elevated temperature curing agents for phenolic novolac resins. Since the oxazolidines are liquids, they should first be adsorbed onto a solid carrier such as silica or wood flour, prior to mixing with the solid novolac. Reactivity can be adjusted by the choice of oxazolidine, as reviewed above. If necessary, cure speed can be increased by the addition of acids such as salicylic. Cure speed can be reduced through the addition of strong bases, etc., as discussed previously. ANGUS oxazolidines have advantages over the standard novolac curative, hexamethylenetetramine (Hexa). During cure, Hexa can generate significant amounts of ammonia, a concern in some applications such as molding compounds. ANGUS oxazolidines generate only minimal levels of ammonia during curing of novolacs. Another oxazolidine advantage (over Hexa) is that they are more easily incorporated into molding compounds, with the potential for shorter mixing times. Low viscosity oxazolidine. Used as crosslinking and curing agent for urea- and melamine-formaldehyde, phenolic/resorcinol adhesive resins and for resorcinol and tannin based wood bonding adhesives. Imparts great flexibility and elongation characteristics, and provides improved solvent resistance in urea- and melamine-formaldehyde based finished products. Applications with resorcinol containing resins: woodbonding adhesives, tire cord adhesives,and resorcinol modified starch adhesives.