19 сентября, 2015 
Malyar True water soluble polymers as previously discussed, are usually those having repeating polar groups in the polymer chain, and are water soluble in their own right, typical groups being hydroxyl, ether, carbonyl, amide, etc.
Water reducible, or water thinnable, synthetic polymers are usually acidic, typically containing carboxyl groups built into the polymer chain. These require neutralisation with a base, with ammonia, triethylamine, dimethyl aminoethanol being typical, and often the use of cosolvents, such as glycol ethers, to produce complete compatibility with water.
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The majority of polymers used in industrial coatings are of the carboxyl functional type and when neutralised, they produce a quaternary amine or ammonium salt of the polymer which is water reducible, as shown in Figure 7-6.
Figure 7-6: Neutralisation of Acid Functionality.
Polymers with basic groups built into the polymer chain have been used for water reducible coatings. The majority of commercial applications, however, are in the manufacture of ‘cationic’ electrocoat resins. Neutralisation of these polymers is usually obtained by using carboxylic acids, such as acetic acid, as shown in Figure 7-7.
POLYMER]— NR2 + R’COOH———— ► [POLYMER]— NR^H* R’COO
Figure 7-7: Neutralisation of Base functionality.
Many types of synthetic polymers can be rendered water reducible utilising this principle, and these will be dealt with in the individual volumes of this series of eight books.
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