Лако-красочные материалы — производство

The textile market has traditionally been the largest consumer of polyurethane adhesives. There are a number of high-volume applications, including textile lamination, integral carpet manufacture, and rebonded foam. Textile lamination occurs through either a solu­tion coating process or flame bonding. Flame bonding textile lamination is accomplished by melting a polyurethane foam by flame and then nipping the foam between two textile rolls while it is still tacky. Integral carpet manufacture describes carpeting that is manu­factured by attaching either nylon, wool, or polypropylene tufts that are woven through a polypropylene scrim with a urethane adhesive to a polyurethane foam cushion in a con­tinuous process. Rebonded foam is made using scrap polyurethane foam bonded together with a urethane prepolymer and is used primarily as carpet underlay. Durability, flexibil­ity, and fast curing speeds are all critical parameters for these applications.

Foundry core binders are isocyanate-cured alkyd or phenolic adhesives used as binders for sand used to produce foundry sand molds. These sand molds are used to cast iron and steel parts. A fast, economical cure of the sand mold is required under ambient conditions.

Packaging adhesives are adhesives used to laminate film to film, film to foil, and film to paper in a variety of packaging constructions. A broad variety of products are sold to this market, with solvent-based, high solids, 100% solids, and waterborne adhesives all being used. Polyurethane adhesives are considered one of the high-performance products offered to this industry because of their excellence in adhesive properties, heat resistance, chemical resistance, and fast curing properties. Polyurethane adhesives can also be designed to meet U. S. Food and Drug Administration approval, a requirement for food packaging applications.

Solvent-borne adhesives represent the majority of the volume in the packaging market, with both one — and two-component systems being used. Waterborne polyurethane adhesives are a much smaller segment that has been driven by environmental considera­tions. Growth has slowed in recent years because of generally inferior performance com­pared to solvent-based adhesives and because most of the major converters have already made capital investments in solvent recovery systems.

Isocyanates are used in the forest products industry to adhesively bond wood chips, which are then pressed to form particleboard and oriented strandboard. Urethanes are also used to fill knotholes and surface defects in finished plywood boards (‘‘plywood patch’’). These filled systems must cure rapidly and be sanded easily.

The transportation market has used polyurethane adhesives for such diverse appli­cations as bonding FRP and sheet molding composite (SMC) panels in truck and car applications, polycarbonate headlamp assemblies, door panels, and weatherstrip flocking.

The construction market for polyurethane adhesives consists of a variety of applica­tions, such as laminating thermal sandwich panels, bonding gypsum board to wood ceiling joists is modular and mobile homes, and gluing plywood floors. Early green strength, low shrinkage, and high bond strength are critical properties.

The furniture industry uses polyurethane adhesives to bond veneers of various com­position to boardstock and metal substrates. Both waterborne and solvent-based adhe­sives are used.

Footwear is a sizable niche for polyurethane adhesives that are used to attach the soles. Polyurethane adhesives compete primarily with neoprene-based adhesives and have replaced much of the neoprene volume due to improved performance. However, the over­all market has declined as U. S. manufacturers have moved production overseas.