Self-Emulsifying Latex

The principal of formation of this type of polyurethane elastomer medium, based on a cationic urethane latex, is where an isocyanate-terminated prepolymer derived from either a polyester or polyether diol and toluene diisocyanate is first chain-extended with an alkyl diethanolamine to yield a relatively low molecular weight urethane capable of further chain-extending reactions. Emulsification occurs when the partially extended urethane is added with high-speed mixing to 3% aqueous acetic acid. Curing of the latex takes place either by reaction of water with the terminal isocyanate groups or by reaction with water-soluble diamines. 

When triethanolamine is used as a third component in the preliminary chain extension step, at an NCO/OH ratio of 1 5, the resulting product 

Reaction sequence for the formation of an aqueous polyurethane elastomer. 

Special methods are necessary for the production of polyurethane dispersions because of the thermodynamically unstable nature of these two-phase systems. A simple application of the emulsion polymerization techniques for isocyanate polyaddition reactions is not possible, due to the reactivity of the NCO group with water. The extreme water sensitivity of all polyurethane preparation procedures which calls for the complete absence of water is obviously a major problem to be overcome in their preparation. It is surprising, given the basic hydrolytic degradability of polyurethane elastomers, to find that polyurethane latex has good long-term stability when it is a two-phase system. This is in contrast to the situation that applies when it is present in a one-phase system. 

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Tackifiers to produce pressure-sensitive adhesives were also prepared as a latex. Self-emulsifying resin or rosin composition, useful as tackifiers for ad-... 

Several industrial systems involve emulsions, of which the following are worthy of mention. Food emulsions include mayonnaise, salad creams, deserts, and beverages, while personal care and cosmetics emulsions include hand creams, lotions, hair sprays, and sunscreens. Agrochemical emulsions include self-emulsifiable oils that produce emulsions on dilution with water, emulsion concentrates with water as the continuous phase, and crop oil sprays. Pharmaceutical emulsions include anaesthetics (O/W emulsions), hpid emulsions, and double and multiple emulsions, while paints may involve emulsions of alkyd resins and latex. Some dry-cleaning formulations may contain water droplets emulsified in the dry cleaning oil that is necessary to remove soils and clays, while bitumen emulsions are prepared stable in their containers but coalesce to form a uniform fihn of bitumen when apphed with road chippings. In the oil industry, many crude oils (e.g.. North sea oil) contain water droplets that must be removed by coalescence followed by separation. In oil slick dispersion, the oil spilled from tankers must be emulsified and then separated, while the emulsification of waste oils is an important process for pollution control. 

Polyurethane acrylate (PU-A) containing a double bond and COOH group was synthesised by the stepwise reaction of TDI, polyetherdiol, dimethylolpropionic acid (DMPA) and 2-hydroxypropyl acrylate (HPA). The PU-A was neutralised with triethylamine and self-emulsified in water to form the PU-A emulsion seed. The seeded emulsion copolymerisation of methyl methacrylate (MMA) onto the PU-A seed was carried out at 80C under soap-free conditions and an anionic latex of P(UA-MMA) was obtained. The structure of the P(UA-MMA) copolymer, its latex properties and the cast film were significantly affected by the amounts of HPA, DMPA and MMA. The results were discussed. 21 refs. 

Uses Dispersant, emulsifier, wetting agent, dispersant, foaming agent for acrylic and vinyl acetate emulsions, self-crosslinking latexes, textiles Regulatory Canada DSL listed... 

Uses Emulsifier, thickener for cosmetic applies. self emulsifying lubricant, softener in textiles defoamer for latex paints Properties Sol. HLB 11.6 Canocol MS600 [Centro China]... 

Chem. Descrip. Organo-modified silicone-based defoamer Uses Defoamer in aq. applies., e.g., inks, coatings, adhesives, cements, latex-containing formulations Features Self-emulsifying... 

Ceral 165 Ceral CK Ceral LE Ceral MA Ceral ME Ceral MET Ceral MEX Ceral ML Ceral TN emulsifier, seafood Soda Phos (FG) emulsifier, seal coatings lndulin ISE emulsifier, sealants Dapro DF 7005 Dapro DF 7010 Isode-cyloxypropylamine acetate Niaproo Anionic Surftictant4 emulsifier, sec. oil recovery Duoquad T-50 Tallowdimonium propyl-trimonium dichloride Triton RW-20 Triton RW-50 Triton RW-150 emulsifier, selenium sulfide Dihydrogenated tallow phthalic acid amide HallSta TAB-2 Flake emulsifier, self-crosslinking latexes Aerosol 501... 

Uses Surfactant, w/o and aux. o/w emulsifier for latex and aq. paints, solv. and solventless coatings, min. oil-based defoamers, inks, dry cleaning soaps emollient and lubricant in cosmetic creams and lotions Features Self-dispersing... 

Fitch and Tsai describe the preparation of monodisperse, emulsifier-free latexes made from methyl methacrylate and stabilized solely by end-groups [1]. The initiator system was persulfate-bisulfite-iron ((R-3) and (R-4)) and the temperature was always 30 °C. At a constant rate of initiation they found that the number of particles, N, was independent of the initial monomer concentration over the range 0.00380 to 0.0951 molar, while the particle diameter increased from 35.4 to 105.4 nm. In another experiment at a lower R , they obtained a final particle diameter of 172 nm and JV=1.1 X 10 1 , compared to Z)=68.7 nm and JV = 1.8x 10 1 at the same monomer concentration (0.035 M) but higher R,-. They estimated in the former case that each ionic group occupied 24.7 nm at the point when self-stabilization by... 

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