Reactive polyurethane

In the CSIRO process, a reactive polyurethane prepolymer is appHed to a garment from perchloroethylene. The garment is then pressed and subsequendy steamed in an oven. A second polymer may sometimes be used in conjunction with the prepolymer. When this is employed, the process is termed the Serolan BAP Process (178). A number of alternative treatments are being investigated to achieve finishes that are more environmentally friendly (179). 

Two-package-reactive polyurethane Tough hard Good Fair Fair Good Good Some yellowing and chalking Difficult... 

Moisture-reactive polyurethane Very tough ahrasion-resistant Fair Fair Fair Good Good Fades in light yellows in shade Difficult... 

For those products laminated using reactive polyurethane based adhesives, suppliers have been aware for many years of the potential migration of amines formed by the reaction of unreacted isocyanate monomer with water and recommend that laminated products are given time to fully cure before they are used in contact with food. Adhesives have been developed that contain low levels of monomeric aromatic isocyanates, in order to reduce any potential migration of aromatic amines into food in critical applications. Such adhesives are not considered to present any notable amine migration hazard unless used in high-temperature applications. 

Recently Benali et al. (2004) reported the development of a new laboratory-made system that allows the combination of rheometric (Alessi et al, 2005) and spectroscopic (Fourier-transform-near infrared (FT-NIR) spectroscopy) measurements for reactive polyurethane materials along the lines of these principles. 

Richter and Macsoko (1980) describe the chemoviscosity of a reactive polyurethane (4,4 -diphenyl methane diisocyanate, polyester triol and dibutyltin dilaurate catalyst) reasonably well by the following model ... 

Reactive Polyurethane Hot-Melt Adhesives (Solvent-Free)... 

The most technologically advanced products are used for waterproofing and pipeline coatings. These products are also based on dispersion of asphalt in the above mentioned solvents but reinforced with addition of polymer. The addition of polymer modifies the plastic behavior of asphalt and renders it elastomeric. Additional solvents are usually added to improve the solubility of polymeric components. Reactive polyurethanes are the most frequently used modifiers for waterproofing hquid membranes. Toluene and xylene are the... 

Vircol (Series), Reactive polyurethane flame retardants, Albright Wilson Americas Virgaloy, PC/PMMA blend, MRC Polymers Inc. Virtual Gibbs, CAM software, Gibbs and Associates... 

Reactive polyurethane adhesives polyurethane prepolymers with terminal hydroxyl groups or terminal isocyanate groups. Uses plastics, metals, silicate-containing materials. 

Reactive polyurethane hot-melt adhesives, one-pack, setting under the influence of atmospheric moisture. Uses bookbinding (high-quality perfect bindings), wood gluing, shoe manufacturing. 

Reactive Polyurethane Adhesives date back to the late 1930s and acquired their present economic significance over the past decades [50]-[52]. They are distinguished... 

Chemically reactive polyurethanes include both one- and two-component systems. One-component systems are usually based on a polyether polyol treated with a polyisocyanate to give an isocyanate-terminated polymer. A one-component system cures when exposed to moisture at room temperature. One-component polyurethane hot-melt adhesives are also cured by moisture after application. Two-component systems result from the reaction of low molecular mass polyols and isocyanates or from isocyanate-terminated prepolymers with either polyols or polyamines. Two-component systems cure at room and/or elevated temperatures. 

Lamination of Paper and Board. Adhesives based on starch, dextrin, glutin and poly(vinyl alcohol), and also emulsion adhesives, mainly polyfvinyl acetate), are used for the lamination of paper and board. Only when high initial tack and a lay-flat effect are required are hot glues based on glutin still in use. Starch-based adhesives modified with silicate, casein-stabilized copolymer dispersions, and rubber latices are used in the lamination of paper to aluminum foils. Modified polyacrylate solutions and reactive polyurethane adhesives are used mainly for paper-to-plastic lamination. 

EVA hot-melt adhesives have heat resistance up to 85 T, polyolefin and polyamide hot-melt adhesives up to 130 °C, and reactive polyurethane hot-melt adhesives up to 150 °C. The cold resistance lies between -20 and -30 °C in the case of polyurethane-based hot-melt adhesives, it is even lower than - 30 °C. 

Adhesives for Plastic Floor Covering. Solvent-free adhesives based on acrylic and vinyl acetate - ethylene - acrylic emulsions are used for bonding vinyl, synthetic rubber, and polyolefin flooring. Solvent-containing contact adhesives (rubber- or polychloro-prene-based) still are used for some applications (e.g., stairs). When water resistance is required, reactive polyurethane or epoxy resin adhesives are preferred to waterborne emulsions. 

Verdejo, R., G. Jell, L. Safinia, A. Bismarck, M. M. Stevens, and M. S. P. Shaffer. 2009. Reactive polyurethane carbon nanotube foams and their interactions with osteoblasts. 

Some reactive polyurethane adhesives such as one- and two-component ones are particularly suitable for wood bonding. They are currently being used for the bonding of parquets and other wood flooring, mainly because of their strength and resistance. They are also being used for bonding of heavy duty rubber floor in commercial areas with heavy foot traffic [24]. 

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