Catalysts for polyurethane coatings

Polyurethane coatings, one of the most important coating systems among the modern high performance coatings, are two-component systems based on polyols and isocyanates. Curing occurs 

While dibutyltin dilaurate has been the most commonly used catalyst over the years, it is being replaced by safer alternatives such as bismuth and zinc carboxylates. Zirconium-based catalysts are preferred in waterbased two-component systems because of their better selectivity for isocyanate-hydroxyl reactions over isocyanate-water reactions. 

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Other areas of use are in the polyvinylchloride (PVC) industry as a stabilizer, in which the organotin acts as a Lewis acid to scavenge the HCl released during extrustion. Organotin species are also used as catalysts for polyurethane coatings. Si cross-linking. 

Dabco . [Air Prods.] Chain extender catalyst for polyurethane, coatings, foam crosslinkmg agent... 

Polycat . [Air Prods. Air Prods. Nederland BV] Tert amine or its acid salts catalyst for polyurethane coat-... 

Uses Heat stabilizer for PVC catalyst for polyurethane coatings... 

Uses Catalyst for polyurethane drier for coatings ManuUDistrib. OM Group Pelron Shepherd Trade Names Nuodex Octoate Potassium 15%... 

Triethylenediamine (l,4-diazabicyclo-2,2,2-octane, DABCO) n. This tertiary diamine, whose structure is shown below, is the most widely used amine catalyst for polyurethane foams, elastomers, and coatings. It is soluble in water and polyols. 

Reaction of isocyanates with different active H-compounds that form the fundamental basis for polyurethane coating systems are shown in Figure 2.60. The order of relative rates for these reactions is -NH -OH > H O > -COOH. Many types of catalysts are available that are used to control these reactions. It should be noted that while urethanes are produced only from reaction of isocyanates with alcohols, other reactions are also effectively controlled and used in different polyurethane coating systems. 

Uset As pesticide (I328), in algaecidal and water repellent coatings (175 ). As catalyst for polyurethan synth. (1209). 

Use for antifouling coatings (2302), as foaming catalyst for polyurethan ( 50). (i) Biol, activity as fungicide... 

The characters used here correspond to the synthetic scheme in the introduction to Chapter. 5 5 1 (a) Use as catalyst for polyurethan synthesis (l 60). (b) Use as fungicide in surface coatings (29T5 ... 

The mono- and disubstituted organotins considered here are used as stabilizers in PVC or as catalysts for the production of electrodeposited coatings (mainly in motor vehicle primers), sihcone rubbers, esterification and powder coatings, and polyurethanes, as well as for coating glass. 

Polyurethane adhesives were prepared by mixing polyol, diisocyanate (MDI, TDI or HDI), solvent (DMF, benzene or ethylace-tate), and catalyst (T-9) in the following fashion The diisocyanate dissolved in half of the total solvent volume was mixed with two-thirds of the polyol in one-fourth of the solvent in the presence of a trace of the catalyst. The mixture was heated to 50°C until an exothermic reaction starts then, heat was temporarily removed and reapplied for 10 min to maintain a temperature of 80°C. The rest of the polyol, catalyst, and solvent were then added and mixed completely. The resin was ready for application when the consistency of the mixture had reached a suitable level. The adhesive was spread on 11 3/4" x 4 1/2" x 3/4" wood (hard maple or southern pine) strips. The moist adhesive-coated surfaces were exposed to ambient air (vented hood) for 20-30 seconds if DMF was used as solvent, or for 3-5 minutes if either benzene or ethylacetate was used. After pressing (100 psi), the strips were cut into small shear blocks and tested according to ASTM Standard D905-49. Polyurethane coatings were prepared by mixing the polyol (80 parts) in ethylacetate (60 parts) and toluene (40 parts), with a solution of TDI (53 parts) in 80 parts ethylacetate and 30 parts toluene, and T-9 catalyst... 

Curitbane . [Air ProdsyPolyurethanes] liq. catalysts amine curing agent for polyurethane intermediate in mfg. of polyamides, pdyimides, coatings, plastics. 

Ether derivatives of condensation products of nonylphenol have proved of value in several applications. Thus, methylene bis(nonylphenol) with epichlorhydrin afforded an intermediate which was used for example with diethanolamine in the presence of the basic catalyst, benzyidimethylamine, to furnish a ring-opened polyol of value in polyurethane coatings (ref.31). 

Conductive polymer nanocomposites may also be used in different electrical applications such as the electrodes of batteries or display devices. Linseed oil-based poly(urethane amide)/nanostuctured poly(l-naphthylamine) nanocomposites can be used as antistatic and anticorrosive protective coating materials. Castor oil modified polyurethane/ nanohydroxyapatite nanocomposites have the potential for use in biomedical implants and tissue engineering. Mesua ferrea and sunflower seed oil-based HBPU/silver nanocomposites have been found suitable for use as antibacterial catheters, although more thorough work remains to be done in this field. ° Sunflower oil modified HBPU/silver nanocomposites also have considerable potential as heterogeneous catalysts for the reduction of nitro-compounds to amino compounds. Castor oil-based polyurethane/ epoxy/clay nanocomposites can be used as lubricants to reduce friction and wear. HBPU of castor oil and MWCNT nanocomposites possesses good shape memory properties and therefore could be used in smart materials. ... 

The major applications for polyurethane catalysts are in flexible and rigid foam, which account for over 80% of the catalyst consumption. Other applications are in microcellular reaction injection-molded (RIM) urethanes for automobile bumpers and a variety of noncellular end uses such as solid elastomers, coatings, and adhesives. 

Organometallic salts, such as organotin catalyst, encourage linear chain extension and are used in flexible slabstock, rigid foam, and a variety of noncellular elastomer and coating applications. Stannous octoate is the most broadly accepted catalyst of this type for polyurethane formulation, although other organotins and potassium salts are also used. 

For baking enamels and wire and powder coatings, blocked isocyanates are used. Blocked polyurethane coatings do not cure below a certain threshold baking temperature. Catalysts, such as tertiary amines or organometallic tin compounds, are used to lower the curing temperature. 

Use As catalyst for curing polysiloxane (2951) polyurethan coatings (1725) and rubber (539a), for preparation of polyurethan (979 2318) effect on stability and performance of product (329) ... 

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