Acidity polyester polyols

Polyester Polyols. Initially polyester polyols were the preferred raw materials for polyurethanes, but in the 1990s the less expensive polyether polyols dominate the polyurethane market. Inexpensive aromatic polyester polyols have been introduced for rigid foam appHcations. These are obtained from residues of terephthaHc acid production or by transesterification of dimethyl terephthalate (DMT) or poly(ethylene terephthalate) (PET) scrap with glycols. 

Polyester polyols are based on saturated aHphatic or aromatic carboxyHc acids and diols or mixtures of diols. The carboxyHc acid of choice is adipic acid (qv) because of its favorable cost/performance ratio. For elastomers, linear polyester polyols of ca 2000 mol wt are preferred. Branched polyester polyols, formulated from higher functional glycols, are used for foam and coatings appHcations. Phthalates and terephthalates are also used. 

Powder coatings are formulated from the reaction product of trimethylolpropane and IPDI, blocked with caprolactam, and polyester polyols. The saturated polyester polyols are based on aromatic acid diols, neopentyl glycol, and trimellitic anhydride for further branching. To avoid the release of caprolactam in the curing reaction, systems based on IPDI dimer diols are used. 

Synthesis MDI prepolymer with 1000 MW polyester polyol, NCO/OH = 2.0, chain-extended with 1,4-butandiol, acid number of polyester 0.6. 

Hie most representative member of this class of polyesters is the low-molar-mass (M 1000-3000) hydroxy-terminated aliphatic poly(2,2/-oxydiethylene adipate) obtained by esterification between adipic acid and diethylene glycol. This oligomer is used as a macromonomer in the synthesis of polyurethane elastomers and flexible foams by reaction with diisocyanates (see Chapter 5). Hydroxy-terminated poly(f -caprolactonc) and copolyesters of various diols or polyols and diacids, such as o-phthalic acid or hydroxy acids, broaden the range of properties and applications of polyester polyols. 

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... 

Isocyanates react with carboxylic acids to form amides, ureas, anhydrides, and carbon dioxide, depending on reaction conditions and the structure of the starting materials (Scheme 4.13). Aliphatic isocyanates more readily give amides. Aromatic isocyanates tend to react with carboxylic acids to first generate anhydrides and ureas, which at elevated temperatures (ca. 160°C) may further react to give amides. In practice, the isocyanate reaction with carboxylic acid is rarely utilized deliberately but can be an unwanted side reaction resulting from residual C02H functionality in polyester polyols. 

Polyester polyols, 25 464 468 Polyester resin(s), 11 302 coating resins, 7 104-106 cyclopentadiene and dicyclopentadiene applications, 8 230 flammability of, 20 115-116 properties in powder coating, 7 43t standard test methods for, 20 11 It unreinforced, 10 187t weathering of, 20 116 Polyester resin-based powder coatings, organic titanium compounds in, 25 125 Polyester resin composites, 26 762-763 Polyester resin formulations ingredients of, 20 96t unsaturated, 15 511-512 Polyesters, 10 185-189, 497 12 655-656. See also Thermoplastic polyesters Unsaturated polyesters acid resistance of, 20 7-8 antioxidant applications, 3 121 aromatic ionic, 23 722 based on 1,4-cyclohexanedimethanol, 12 674-675... 

Pol30irethane chemistry began with the utilization of polyester polyols, principally prepared from diacids such as adipic acid and various diols. Later, polyester polyols were replaced by polyether polyols due to improvements in mechanical properties and moisture resistance. Polyether polyols now constitute the greater part of the volume in pol3airethane polymers [1]. 

Much work has been done on the incorporation of castor oil into polyurethane formulations, including flexible foams [64], rigid foams [65], and elastomers [66]. Castor oil derivatives have also been investigated, by the isolation of methyl ricinoleate from castor oil, in a fashion similar to that used for the preparation of biodiesel. The methyl ricinoleate is then transesterified to a synthetic triol, and the chain simultaneously extended by homo-polymerization to provide polyols of 1,000, 000 molecular weight. Polyurethane elastomers were then prepared by reaction with MDl. It was determined that lower hardness and tensile/elongation properties could be related to the formation of cyclization products that are common to polyester polyols, or could be due to monomer dehydration, which is a known side reaction of ricinoleic acid [67]. Both side reactions limit the growth of polyol molecular weight. 

Since the early days of polyurethane discovery, the technology has focused on isocyanate reactions with polyesters or polyethers. The differences will be discussed in later sections. These reactions are responsible for the growth of the polyurethane industry. The polyesters of interest to polyurethane chemists terminate in hydroxyl groups and are therefore polyols produced by the polycondensation of dicarboxyhc acids and polyols. An example is a polyol with a polycarbonate structure (Figure 2.3). 

In a fully synthetic oil, there is almost certainly some mineral oil present. The chemical components used to manufacture the additive package and the viscosity index improver (VI) contain mineral oil. When all these aspects are considered, it is possible for a "fully synthetic" engine oil to surpass mineral oil (Shubkin, 1993). Synthetic oils fall into general ASTM classification (a) synthetic hydrocarbons (poly-a-olefins, alkylated aromatics, cycloaliphatics) (b) organic esters (dibasic acid esters, polyol esters, polyesters) (c) other fluids (polyalkylene glycols, phosphate esters, silicates, silicones, polyphenyl esters, fluorocarbons). 

Dow also developed polyurethane foams from polyols via hydroformylation of fatty acids. The foams have properties which are comparable to foams from petrochemicals in terms of density and flexibility. The advantages of using sustainable feedstocks in viscoelastic foams are increased load bearings and tensile and tear properties [39, 40]. The hydroformylation and consecutive hydrogenation of fatty acids derived from seed oil can also be used to form low viscosity polyester polyols. Therefore, fatty acid methyl esters are transesterified with diols, e.g., glycol (Scheme 12). The polymer contains chemically active hydroxy groups which can be used for polyurethanes in coating applications [41]. 

The polyester type polyols used in polyurethane laminating adhesives are produced by the direct esterification of polyfunctional carboxylic acids and glycols. Polyester polyols provide the soft segment in polyurethane products giving the adhesive flexibility. Ester groups of the polyol also contribute to adhesion. Polyester polyols provide limited wetting and adhesion of olefinic surfaces with amide slip additives (in contrast to polyether polyols). Typical examples include adipic acid, caprolactone, maleic acid and isophthalic based polyester polyols. 

Tin compounds such as dibutyl tin dilaurate at -30 0 ppm are found in polyester polyols. Phosphoric acid can be found in polyols for control of pH and side reactions. 

Transesterification performed at 170-200°C in the presence of aliphatic carboxylic acids, such as adipic acid, after the depolymerization of PET in EG and propylene glycol leads to unsaturated polyesters. These materials are used in foam production or for the production of polyurethanes and polyester polyol copolymers [7-9]. 

Polyester polyols are the esters of dicarboxylic acids with bivalent alcohols, resulting in intermediate products with two terminal or functional OH groups (diol). The dicarboxylic acids may be either aliphatic or aromatic, which is also true of the... 

U.S. 6592856 (2003) Giles et al. (Unilever) Combination of conditioning agents emulsified silicones, cationic polymers, fatty acid polyesters of cyclic polyols and/or sugar derivatives Improved hair softness and ease of combings, especially for damaged hair, through environmental or harsh mechanical or chemical treatments... 

Cellulose acetate phthalate, diallyl phthalate, dyes and pigments, herbicides, isatoic anhydride. pfceaol-phthalem, phthalimide, polyester-polyols, 4 5ulfophthaiic acid, tctrachloro and tetrabromophthafic anhydrides,-. 

---