Cold-setting urea

Urea resin adhesives, by the use of the proper hardener, may be set either by heat or at room temperature. For room temperature curing, the hardener may be ammonium chloride, together with basic materials like calcium phosphate to neutralize excess acid that might damage the wood. Cold set or room temperature set adhesives are those that set satisfactorily at 20 —30°C, whereas a hot set adhesive generally means one that is set above 99 °C. 

U.S. Pat. No. 5,767,178 [24] describes a thermoset (or a cold-set) composition of a phenol-aldehyde, a urea-aldehyde, or a polyurethane, mixed with cellulose fibers and latex, containing magnesium oxychloride or magnesium oxysulfate to improve fire resistance of the resulting composite. 

Exactly the same type of approach can be used for the formulation of other polycondensation adhesives. For example, the formulation of melamine urea formaldehyde adhesive resins for wood panel products can also be successfully approached in the same way as has been shown above for the cold-setting PRF adhesives. 

FURAN Combination resins of Phenol Urea Furfuryl alcohol Formaldehyde Cold-set with acids - low Formaldehyde Phenol Furfuryl alcohol Hydrogen sulphide Acid mists Resins and acids must be kept apart (unless sand is present) as they are vigorously exoAermic when in contact... 

Acid catalysts n. Acids which may be either organic or inorganic, or salts from these acids which exhibit acidic characteristics. They are used to promote or accelerate chemical reactions, and find special applications in the manufacture and subsequent hardening of synthetic resins. Acid catalysts have been employed in the manufacture of polymerized drying oils, coumarone, urea, phenol-and melamine-formaldehyde resins, and in the cold-setting of compositions containing the last three named resins. Odian GC... 

Urea formaldehyde adhesives are not as strong or as moisture resistant as resorcinol adhesives. However, they are inexpensive, and both hot- and cold-setting types are available. Maximum service temperature of urea adhesive is approximately 140°F. Cold-water resistance is good, but boiling-water resistance may be improved by the addition of melamine formaldehyde or phenol resorcinol resins. Urea-based adhesives are used in plywood manufacture. 

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. 

Diethyl-1,2-dihydro-1-phenyl-2-propylpyridine accelerator, coatings Amyl acid phosphate accelerator, cold-cure cements Dibutyl xanthogen disulfide accelerator, composites 1-Phenyl-3,3-dimethyl urea accelerator, concrete setting Calcium formate accelerator, cosmetics Sodium persulfate accelerator, CR... 

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