Urethane diols

Finally, some waterborne coatings incorporated reactive diluents, as in high solids coatings. For example. Blank (1992) describes using a urethane diol as a reactive diluent to replace glycol ether cosolvents in emulsion coatings. 

HOCH HpCHjCHjOCOM R-NHCOOCHjCHjOO CHpH Urethane diol... 

Chem. Descrip. Aliphatic urethane diol resin modifier Uses Modifier for amino or isocyanate crosslinked coatings, elastomers, and adhesives, automotive, aerospace, wood/paper, and general industrial coatings, and inks Features Water-sol. reduces VOCs... 

Scheme 3.2 Synthesis of phosphorus-containing polyurethanes via transesterification of diesters of H-phosphonic acids with urethane diols.

The adhesives can have open times varying from a few seconds up to about 10 minutes to match application requirements. Improvements related to adhesives that have long open times and/or high green strength via the use of urethane diols or polyurethane-acrylic hybrid systems has been reported [42]. 

Phosphorus-Containing Diols and Polyols. The commercial development of several phosphoms-contaiuing diols occurred in response to the need to flame retard rigid urethane foam insulation used in transportation and constmction. There are a large number of references to phosphoms polyols (111) but only a few of these have been used commercially. 

In the second step, a papermaking method is also used for the fine fibers, less than 0.1 tex (1 den). This process is usually followed by a high pressure water jet process instead of the third step. In the fourth step, to obtain the required properties in specific appHcations, a polyurethane is selected out of the segmented polyurethanes, which comprises a polymer diol, a diisocyanate, and a chain extender (see Urethane polymers). A DMF—water bath for coagulation is also controlled to create the adequate pore stmcture in combination with fibers. 

Preparation of the polymer can be carried out in glass equipment at atmospheric pressure at temperatures typically above 100°C, but the higher pressures in an autoclave result in much faster reaction rates. Each polymer molecule which used butanol as a starter contains one hydroxyl end group as it comes from the reactor diol-started polymers contain two terminal hydroxyls. Whereas a variety of reactions can be carried out at this remaining hydroxyl to form esters, ethers, or urethanes, this is normally not done and therefore lubricant fluids contain at least one terminal hydroxyl group (36). 

Methylenedi(cyclohexyhsocyanate) (45) [5124-30-1] (MDCHl, Desmodur W) is the dominant derivative of MDCHA and is used in light-stable urethanes. Polyurethane physical properties are dependent on the diamine geometric isomer composition used for the derivative diisocyanate which reacts with diol (87). 

Stmctural and chemical modification of urethane containing polymer matri-ces with macrocycles - calixarenes having reactive hydrazide groups have been carried out and stmcture, physico chemical and sensor properties of polyure-thanesemicarbazides (PUS) synthesised have been studied. The polymers obtained (on the base of polypropylene glycol MM 1000 and polysiloxane diol MM 860, hexamethylene diisocyanate and calixarene dihydrazide) are identified by IR-spectroscopy, size exclusion chromatography (SEC), DSC, WAXS and SAXS methods. 

Crystalline polyesters are highly important as adhesive raw materials. They are normally crystalline waxes and are highly symmetrical in nature, which can aid the crystallization process [26]. Poly(hexamethylene adipate) and poly(caprolactone), shown in Table 2, are only two of the many crystallizable backbones. Poly(ethylene adipate) and poly(letramethylene adipate) are also commonly used in urethane adhesives. The crystalline polyesters are used in curing hot melts, waterborne polyurethanes, thermoplastic polyurethanes, and solvent-borne urethane adhesives. The adipates are available mostly as diols. The poly(caprolactones) are available as diols and triols. 

A urethane is typically prepared by nucleophilic addition reaction between an alcohol and an isocyanate (R—N = C=0), so a polyurethane is prepared by reaction between a cliol and a diisocyanate. The diol is usually a low-molecular-weight polymer (MW 1000 amu) with hydroxyl end-groups the diisocyanate is often toluene-2,4-diisocyanate. 

Polyester polyols (Scheme 4.4) are prepared by condensation polymerization of dicarboxylic acids and diols. An excess of diol ensures OH functional product, minimizing die possibility of residual acid groups which react with isocyanates to generate C02 and act as inhibitors in catalyzed urethane reactions. The reactants are heated at 200-230°C under vacuum to remove the water by-product and drive the reaction to completion. The most common coreactants include adipic... 

Urethane hydrolyzes into an amine, an alcohol, and carbon dioxide. So the possible degradation products of a poly(phosphoester-urethane) are diamines, diols, phosphates, carbon dioxide, and even ureas. Urea is possible because the isocyanate is extremely sensitive to moisture, which would convert the isocyanate to an amino group. One is therefore bound to have traces of diamine in the polymerization that leads to a urea bond in the backbone. We think the cytotoxicity seen in the macrophage functional assay comes from the TDI structure. 

Figure 25.3 b) shows a generic polyester-based polyurethane. The most common polyester repeat units are derived from the polycondensation of adipic acid and a diol, such as ethylene glycol, which results in the structure shown in Fig, 25.4. The average molecular weight of the polyester sequences between urethane links commonly ranges between 400 and 6,000 g/mol. 

Aromatic urethane Poly-1,4-butane diol (spandex)... 

Synthesis of a Urethane Vinyl Ether Oligomer. A urethane vinyl ether oligomer was prepared by the procedure discussed by Lapin.15 Reacting a hydroxyalkyl vinyl ether, an oligomeric diol and a diisocyanate gave and oligomer that had a Brookfield viscosity of 3.7 million mPa-s and a theoretical equivalent weight of 1000 g per vinyl ether double bond. 

Maleate/vinyl ether formulations based on a model unsaturated polyester prepared from maleic anhydride and 1,5-pentane diol and triethylene glycol divinyl ether were studied. At molecular weights of less than about 10,000 the cured films were extremely brittle. When the equivalent weight of the unsaturated polyester was increased by replacing some of the maleic anhydride with succinic anhydride, measurable values for film elongation could be obtained but the cure speed was definitely slower. When either diethyl maleate or isobutyl vinyl ether were added as monofunctional diluents the cure dose needed to obtain 200 MEKDR was increased and the flexibility measured by pencil hardness increased as the amount of diluent was increased. A urethane vinyl ether was synthesized and used to replace DVE-3 and films with increased elongation were obtained at equivalent at dosages as low as 1 J/cm2. 

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