Polybases

In view of the difficulty of arranging esters in a chemically logical sequence they have in the following table been arranged in order of increasing b.ps (liquid) and m.ps (solid). Other esters are given in Tables XI and XII (pp. 543-545). The values for esters of polybasic acids refer to the fully esteriiied product. 

Polyesters from polybasic acids and polyhydric alcohols. Alkyd resins. The condensation of polyhydric alcohols and polybasic acids or anhydrides leads to polj esters known as alkyd resins. The most common member of the group is a glycerol - phthahc acid polymer, and this has led to the term glyptal resins being frequently apphed to the whole group. 

The same is true for polybasic acids, with the proviso that all the carboxyl groups must be changed to aldehyde then it is not necessary to introduce affixes. Examples are... 

COMPOSITEMATERIALS - POLYMER-MATRM - THERMOSETS] (Vol 7) Glycidated polybasic acid... 

The primary and secondary alcohol functionahties have different reactivities, as exemplified by the slower reaction rate for secondary hydroxyls in the formation of esters from acids and alcohols (8). 1,2-Propylene glycol undergoes most of the typical alcohol reactions, such as reaction with a free acid, acyl hahde, or acid anhydride to form an ester reaction with alkaU metal hydroxide to form metal salts and reaction with aldehydes or ketones to form acetals and ketals (9,10). The most important commercial appHcation of propylene glycol is in the manufacture of polyesters by reaction with a dibasic or polybasic acid. 

Esters. Neopentyl glycol diesters are usually Hquids or low melting soflds. Polyesters of neopentyl glycol, and in particular unsaturated polyesters, are prepared by reaction with polybasic acids at atmospheric pressure. High molecular weight linear polyesters (qv) are prepared by the reaction of neopentyl glycol and the ester (usually the methyl ester) of a dibasic acid through transesterification (37—38). The reaction is usually performed at elevated temperatures, in vacuo, in the presence of a metallic catalyst. 

This system of nomenclature has withstood the impact of later experimental discoveries and theoretical developments that have since the time of Guyton de Morveau and Lavoisier greatiy altered the character of chemical thought, eg, atomic theory (Dalton, 1802), the hydrogen theory of acids (Davy, 1809), the duahstic theory (Berzehus, 1811), polybasic acids (Liebig, 1834), Periodic Table (Mendeleev and Meyer, 1869), electrolytic dissociation theory (Arrhenius, 1887), and electronic theory and modem knowledge of molecular stmcture. 

Alkyd resins are produced by reaction of a polybasic acid, such as phthaUc or maleic anhydride, with a polyhydric alcohol, such as glycerol, pentaerythritol, or glycol, in the presence of an oil or fatty acid. The resulting polymeric material can be further modified with other polymers and chemicals such as acryhcs, siUcones, and natural oils. On account of the broad selection of various polybasic acids, polyhydric alcohols, oils and fatty acids, and other modifying ingredients, many different types of alkyd resins can be produced that have a wide range of coating properties (see Alkyd resins). 

Alkyl peroxyesters are commonly named like their nonperoxidic counterparts, except for incorporation of the peroxy- prefix. Trivial names are also commonly used, eg, tert-huty peracetate. Alkyl peroxyesters derived from di- and polybasic peroxyacids use 00- or O- when required to locate groups, eg, 00-tert-huty 0-isopropyl monoperoxycarbonate and 00-tert-huty 0-hydrogen monoperoxymaleate. Descriptions of alkyl peroxyesters have been given in the chemical hterature (1,4—6,19,20,44,168,213). 

The manufacture of alkyd resins (qv), which are obtained by the reactions of polybasic acids or anhydrides, polyhydric alcohols, and fatty oils and acids, consumes about 17% of the phthahc anhydride demand. While materials such as maleic anhydride, isophthahc acid, and fumaric acid can also be used, phthahc anhydride is the most important. The resin provides a binder for coatings that are apphed for either protection or decoration. Ak quahty concerns have put alkyd resins under pressure from water-based coatings which do not emit organic vapors upon drying. 

All d Ingredients Eor each of the three principal components of alkyd reskis, the polybasic acids, the polyols, and the monobasic acids, there is a large variety to be chosen from. The selection of each of these kigredients affects the properties of the reski and may affect the choice of manufacturkig processes. Thus, to both the reski manufacturers and the users, the selection of the proper kigredients is a significant decision. 

Polybasic Acids and Anhydrides. The principal polybasic acids used ki alkyd preparation are Hsted ki Table 2. 

Table 2. Polybasic Acids Used in Alkyd Resin Preparation...

Polybasic acid, (COOH) Polyol, (OH) " Functionahty, Esterification at gel point, %... 

When the alcoholysis step is complete, the polybasic acid(s) and the balance of polyol, if any, are added. The batch is reheated and maintained at about 250°C to carry out the polycondensation step to the desired endpoint, usually a combination of the acid value and viscosity of the resin. 

If the total alkyds consumed in recent years is classified by their dibasic acid component, about 50% belongs to the unmodified phthaHc type, about 28% modified phthaHc type, about 13% based on isophthaHc, and the balance based on polybasic acids other than phthaHc or isophthaHc. The top alkyd resin manufacturers in the U.S. are Cargill, Reichhold, a subsidiary of Dainippon Ink Chemicals, Inc., and Spencer KeUog, now a part of NL Industries, Inc. The median price (52,53), of general types of alkyd resin, soHds base, was 1.98/kg in Nov. 1990 compared to about 440 in 1955, about 660 in 1975, and about 1.54 in 1983, reflecting the increases in raw material cost. 

Aluminum chloride hydroxide [1327-41 -9] [10284-64-7], AlQ(OH)2 [14215-15-7], AlQ2(OH), products, commonly known as polyaluminum chlorides (PAG), are used for a wide variety of industrial appHcations. Other names for PAG are basic aluminum chloride, polybasic aluminum chloride, aluminum hydroxychloride, aluminum oxychloride, and aluminum chlorohydrate. The presence of polymeric, aluminum-containing cations, the distribution of which can differ gready, typifies PAG products. Although the formation of polynuclear aluminum species in solution has been studied for over a century, there is stiU much controversy concerning aluminum polymerization reactions and the resulting product compositions. 

Poly(methyl vinyl ether) [34465-52-6] because of its water solubility, continues to generate commercial interest. It is soluble in all proportions and exhibits a well-defined cloud point of 33°C. Like other polybases, ie, polymers capable of accepting acidic protons, such as poly(ethylene oxide) and poly(vinyl pyrroHdone), each monomer unit can accept a proton in the presence of large anions, such as anionic surfactants, Hl, or polyacids, to form a wide variety of complexes. 

The strong polybase behavior of PMVE is well documented, and interest in this polymer, especially from academic workers, suggests eventual interest industrially. This feature of PMVE cannot be found in acrylates or other inexpensive polymers but is inherent in PMVE polymers. 

Chelating agents that are polybasic acids give two or more hydrogen ions per molecule. The four stages of dissociation of EDTA, eg, are represented by the equations... 

Alkyds. Alkyd resins (qv) are polyesters formed by the reaction of polybasic acids, unsaturated fatty acids, and polyhydric alcohols (see Alcohols, POLYHYDRic). Modified alkyds are made when epoxy, sUicone, urethane, or vinyl resins take part in this reaction. The resins cross-link by reaction with oxygen in the air, and carboxylate salts of cobalt, chromium, manganese, zinc, or zirconium are included in the formulation to catalyze drying. 

Fig. 1. Structures of commercial epoxy resins (a) phenolic novolac epoxy resin, (b) glycidated polybasic acid, (c) glycidated polyamine (A,A,A, A -tetraglycidyl-4,4 -diaminodiphenylmethane [28768-32-3] (TGMDA)), and (d) glycidated bisphenol A.

Possible uses for these polyhydroxy compounds include the preparation of alkyd-type resins with polybasic acids, the formation of ester plasticizers, and the preparation of surface-active agents. 

Polyamide Resins. Another class of polyamide resins, in addition to the Hquid resins used as epoxy hardeners, are the thermoplastic type, prepared generaHy by the condensation reaction of polyamines with polybasic fatty acids. These resins find use in certain hot-melt adhesives, coatings, and inks. Diamines, typicaHy EDA (233), are the principal amine reactant however, tri- and tetramines are sometimes used at low levels to achieve specific performance. 

The phleomycin, bleomycin and related families are widespectrum antibiotics containing the pyrimidine (987) in addition, they have antineoplastic activity and bleomycin is already in clinical use for certain tumours. They were isolated about 1956 from Streptomyces verticillus, and in addition to the pyrimidine portion the molecules contain an amide part (R ) and a complicated part (R ) consisting of polypeptide, an imidazole, two sugars, a bithiazole and a polybasic side chain which can vary widely phleomycin and bleomycin differ by only one double bond in the bithiazole section (78MI21303). The activity of such antibiotics is increased by the addition of simple heterocycles (including inter alia pyrimidines and fused pyrimidines) and other amplifiers (82MI21300). 

Reaction of polyhydroxy compounds with polybasic acids gives rise to condensation polymers containing ester (—COO—) groups. Because of the presence of these groups such polycondensates are known as polyesters and find use in such diverse applications as fibres, surface coatings, plasticisers, rubbers and laminating resins. These materials are discussed in detail in Chapter 25. 

Condensation of polyhydroxy compounds with polybasic acids, e.g. a glycol with a dicarboxylic acid ... 

These resins are produeed by reacting a polyhydric alcohol, usually glycerol, with a polybasic acid, usually phthalic acid and the fatty acids of various oils such as linseed oil, soya bean oil and tung oil. These oils are triglycerides of the type shown in Figure 25.30. R], R2 and R3 usually contain unsaturated groupings. The alkyd resins would thus have structural units, such as is shown in Figure 25.31. 

M Qureshi et al., Recent progress in ion-exchange studies on insoluble salts of polybasic metals Separation Sci. 1972, 7, 615... 

Host at the beginning of 2000, online available at TDS Herrlich GmbH (www.polybase.com)... 

Paraplex. A trademark for a group of alkyd type polymeric materials known as polyester resins. These resins are primarily long chain polybasic acids esterified with polyhydric alcohols such as glycol sebacate, glycerol, or ethylene glycol. Some are oil-modified while others are unmodified polyesters... 

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