Isocyanates adhesives

Another product is made with strands produced by flakers, having dimensions of about 0.8 x 13 x 300 mm (0.030 x 0.5 x 12 in.). The strands are dried and then coated with isocyanate adhesives. The strands are formed into mats with unidirectional orientation and pressed in a steam-through press. The large panels are then sawn into dimension lumber sizes. 

Most blocked isocyanates are solids at room temperature and thus may require the use of solvent. The unblocking temperatures are often fairly high and are energy intensive. Furthermore, certain blocking agents may qualify as volatile organic compounds. For these reasons, the blocked isocyanate adhesives occupy a small, but important segment of the adhesive marketplace. 

However, lignin may find application as a suitable wood-composite adhesive in adhesive formulations if chemically modified in some manner. In this respect, the recent developments with soda bagasse lignin-resorcinol-formaldehyde and lignin-isocyanate adhesives allow for some cautious optimism for the future. 

An emulsion polymer-isocyanate adhesive, a crosslinked polyvinyl acetate adhesive, a resorcinol-formaldehyde adhesive, a phenol-resorcinol-formalde-hyde adhesive, and an acid-catalyzed phenolic-formaldehyde adhesive developed bonds of high shear strength and wood failure at all levels of acetylation in the dry condition. A neoprene contact bond adhesive and a moisture-curing polyurethane hot-melt adhesive performed as well on acetylated wood as untreated wood in tests of dry strength. Only a cold-setting resorcinol-formal-... 

JIS K 6806 1985 Water-based polymer-isocyanate adhesives for wood. JIS K 6860 1974 General recommended practices for atmospheric exposure of adhesive bonds. 

Wood was soaked or impregnated with chemicals. After that they were set in a hot press and pressed at 160 iC/0.5-2MPa for 5-30min. [Heat-Pressed Treatment]. Comparison specimens were set in a hot oven and dried at 160 °C for 2-6hrs. [Heat-Dried Treatment]. Heat pressed material was put on top of each other or untreated material with emulsion polymer-isocyanate adhesives to make a laminated board. 

Chemiflex. [Sanyo Chem. Industries] Blocked isocyanate adhesion promoter forPVCplastisols. 

Isoset . [Ashland/Foundry Prods.] Emulsion polymer/isocyanate adhesive resins found core binders. 

Uses Fleat stabilizer for rigid and plasticized PVC, food-grade polymers, profiles, bottles, pipe, plastisols stabilizer for flooring base coats, artificial leather, wallpaper, conveyor belts compat. with isocyanate adhesion promoter Manuf./Dlstrlb. St. Lawrence Trade Names Baeropan MC 8367 KA Synpron 1522... 

Since an EPI adhesive was first developed in Japan, the Japanese were the first to include EPI adhesives in their standards. The Japanese Industrial Standard (JIS) K 6806-1985 [7] deals with Water Based Polymer — Isocyanate Adhesives for Wood . The Standard describes the quality of the adhesive, the performance properties and the requirements which should be fulfilled to be classified as Class 1 or 2 or used for laminate timber, furniture, decorative veneer, or plywood. 

The reaction of di- and polyisocyanates with hydroxyl-bearing polyesters and polyethers, co-reactants in many isocyanate adhesive applications, produces the strong, polar, hydrogen-bonded, flexible polyurethanes which, when wet, intimately contact and show strong attraction for a variety of surfaces. 

Fig. 8.5. Other isocyanate adhesive-promoting primers PAP and DADI.

Fig. 8.7. Isocyanate adhesive promoter for use with thermoplastic polyurethanes (Desmodur RF, a 20% solution of thiophosphoric acid tris (p-isocyanatophenyl ester) in methylene chloride).

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