Polyurethane emulsion

REZTHANE 1980 is an aqueous polyurethane emulsion designed for pad, reverse roll or engraved roll application. 

GrapHsiz. [Akzo] Polyurethane emulsion surface size and treatment for paper water rqpellatt... 

Chem. Descrip. Waterborne polyurethane emulsion Uses Softener, hand modifier providing high flexibility in pad dyeing of nylon, polyester, rayon, cotton, and blends provides shrinkage control to wool, rayon, silks, dty-clean-only fabric flexible binder for pigment printing, plastics, paper, leather. Aims dear coat for leather, metals, and wood modifier tor other polymers... 

In the USA both standard EPI adhesives, with emulsion adhesive and pMDI, and polyurethane emulsion polymers (PEPs) are used for production of I-beams. These adhesive systems fulfill all the requirements for a structural adhesive [30]. 

Ashland Inc., Speciality Polymers and Adhesives, Columbus, OH 43216, Technical Data Sheet, Isoset Polyurethane/Emulsion Polymer Adhesive (2007). 

Polyurethane emulsions and dispersions in water may also be made by incorporating polar or hydrophilic groups as described in Chapter 9. They are fully reacted, containing urethane and urea groups, are of high molecular weight, and may contain cosolvent. The chemistry of these is complex and beyond the scope of this book. They are used for the same applications as the solution polymers, and as primers for a range of plastic surfaces. 

The preparation of polyurethane lattices is possible in several ways. In one instance special monomers are polymerized in an aqueous medium to produce a thermoplastic polyurethane emulsion. Or thermoplastic polyurethanes made in solution or dissolved in solvents are emulsified in water, then solvent is removed. Or an isocyanate-terminated urethane prepolymer, possibly with hydrophilic branches, is blocked with an appropriate isocyanate blocking agent, and emulsified in water together with a crosslinking agent. 

Adhesives for Laminated Films. Laminated films are currently produced by two techniques lamination and extrusion. In lamination, the low-viscosity adhesive solution is applied by rolls to one of the films in a thickness of a few micrometers and dried. The two films are then combined in the laminator. The adhesives used are either two-component or one-component, moisture-cross-linking polyurethane adhesives, depending on requirements (type of film, sterilization resistance, sealing seam strength, etc.). Besides the traditional solvent-based systems developments have been made in the direction of solvent-free systems (high-solids products) and of polyurethane emulsion-based systems. 

One-part, solvent-borne polyurethane One-part, aqueous polyurethane emulsion ... 

Ex. 4. American Cyanamid supplies 10 Cyanabond textile adhesives which are described as nontoxic, water-based, 30 or 40% solids, prereacted, polyurethane emulsions that provide highly durable bonds when applied to woven, knitted, or nonwoven fabrics. They have an acetic acid-type odor. They may be used on a wide variety of cellulosic and synthetic textile substrates. When applied by established processing techniques they form bonds of cloth-to-cloth and foam-to-fabric that... 

Inversion ofMon cjueous Polymers. Many polymers such as polyurethanes, polyesters, polypropylene, epoxy resins (qv), and siHcones that cannot be made via emulsion polymerization are converted into latices. Such polymers are dissolved in solvent and inverted via emulsification, foUowed by solvent stripping (80). SoHd polymers are milled with long-chain fatty acids and diluted in weak alkaH solutions until dispersion occurs (81). Such latices usually have lower polymer concentrations after the solvent has been removed. For commercial uses the latex soHds are increased by techniques such as creaming. 

Most of the surface sizes used in North America are modified styrene maleic anhydride (SMA) copolymers. Commercially available materials include Scripset (Monsanto/Hercules Inc.), Cypres (Cytec), Sursize (Akzo Nobel), MSA (Morton), NovaCote (Georgia Pacific), and HTl (Hopton Technologies). Styrene acrylate emulsions that are commonly used include Jetsize and Unibond (Akzo Nobel), Basoplast (BASF), and Cypres (Cytec). Other materials used as surface sizes include acrylonitrile acrylate copolymer (Basoplast, BASF), stearylated melamine resin (Sequapel, Sequa), polyurethane (Graphsize, Vining Chemicals), and diisobutylene maleic anhydride copolymers (Baysynthol, Bayer). 

Elastomeric Fibers. Elastomeric fibers are polyurethanes combiaed with other nonelastic fibers to produce fabrics with controlled elasticity (see Fibers, elastomeric). Processing chemicals must be carefully selected to protect all fibers present ia the blend. Prior to scouriag, the fabrics are normally steamed to relax uneven tensions placed on the fibers duriag weaving. Scouriag, which is used to remove lubricants and siting, is normally conducted with aqueous solutions of synthetic detergents and tetrasodium pyrophosphate, with aqueous emulsions of perchloroethylene or with mineral spidts and sodium pyrophosphate. 

History. The first attempts to desensitize RDX were reported by Frankel and Carle ton (Refs 1 thru 5) who made use of polymeric materials such as polyurethanes to coat expl crysts by means of emulsion or soln techniques. The first true PB-RDX was developed in 1952 at the Univ of Califs Los Alamos Lab and consisted of RDX coated with polystyrene plasticized with DOP (Refs 6 21). Since then the Lawrence Livermore Lab has evolved a series of PBX formulations, many of which are listed in Tables 3,4 5. These compns are described in Ref 77... 

G. N. Taylor. Demulsification of water-in-oil emulsions using high molecular weight polyurethanes. Patent GB 2346378,2000. 

Several benzimidazolone pigments are suitable candidates for use in powder coatings based on polyester, acrylic, or polyurethane resin. These pigments satisfy the heat requirements of this application and do not plate out in these media (Sec. 1.6.4.1). Various benzimidazolone pigments even meet the particularly high thermal standards of coil coating. These pigments are also suitable for use in architectural and emulsion paints. 

Urea-formaldehyde resins ABS copolymer Rigid insulation polyurethane Cellulose acetate butyrate Polyesters (PBT, PCT, PET) PE emulsions PS... 

Waterborne polyurethanes that have the performance of solvent-based systems can be made via tailored emulsion polymerization (Hagernrother and Ruttmann, 1990). 

Conducting composite polymer materials have also been prepared from the dispersed phase of concentrated emulsions. Polyurethane/polypyrrole composites [165] were obtained by blending an aqueous suspension of polypyrrole with a HIPE of a chloroform solution of polyurethane in aqueous surfactant... 

Consider the procedure for immobilizing an enzyme using polyurethane technology. A solution of the enzyme is produced in water. The solution is then emulsified with a hydrophilic polyurethane prepolymer. The emulsion is applied to the structural members of a reticulated foam by means of nip rollers. After curing... 

FIGURE 2.16 Nip rollers for forcing prepolymer emulsion into reticulated polyurethane foam web. 

An activated carbon (Nuchar RGC Powder, 879-R-02) was supplied by the Chemical Division of Westvaco, Covington, VA. A slurry of the carbon was made in water and emulsified with a TDI-based hydrophilic polyurethane prepolymer (Hypol 2002, Dow Chemical, Midland, MI). Immediately after mixing, the emulsion was grafted to a 30-ppi polyether polyurethane (Crest Foam T-30, Monachie, NJ.). The amount of carbon was determined gravimetrically to be 29% by weight. 

A hydrophilic polyurethane prepolymer was made according to the procedure taught by Braatz. - The prepolymer was mixed with water at a ratio of 10 parts water to one part prepolymer. The emulsion was poured immediately onto a silicone release liner and allowed to cure for 30 min. It was free of voids and had a density roughly the same as water. For the contraction experiments, the gel was immersed in excess distilled and sterile water for 24 h, tlicii cut with a steel-ruled die into circles 40 mm in diameter. 

While unaffected by water, styrofoam is dissolved by many organic solvents and is unsuitable for high-temperature applications because its heat-distortion temperature is around 77°C. Molded styrofoam objects are produced commercially from expandable polystyrene beads, but this process does not appear attractive for laboratory applications because polyurethane foams are much easier to foam in place. However, extruded polystyrene foam is available in slabs and boards which may be sawed, carved, or sanded into desired shapes and may be cemented. It is generally undesirable to join expanded polystyrene parts with cements that contain solvents which will dissolve the plastic and thus cause collapse of the cellular structure. This excludes from use a large number of cements which contain volatile aromatic hydrocarbons, ketones, or esters. Some suitable cements are room-temperature-vulcanizing silicone rubber (see below) and solvent-free epoxy cements. When a strong bond is not necessary, polyvinyl-acetate emulsion (Elmer s Glue-All) will work. 

---