ketone aldehyde resins with wide compatibility,
process for their preparation, and their use. The invention relates to ketone-aldehyde resins
with wide compatibility comprising cycloaliphatic ketones and, in particular, formaldehyde and,
if desired, further monomers, to a process for their preparation and to their use as hard resin
in paints, printing inks and other coatings, especially in pigment preparations.
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In the reduction of acetaldehyde to ethanol, the carbonyl carbon acquires a hydrogen atom. Given the polarization of the carbonyl group, it should not be surprising that reagent which delivers the hydrogen to the electron deficient carbonyl carbon delivers it as a hydride ion, :H-. Chemists have developed a multitude of reagents that serve as hydride ion donors. We will consider two, sodium borohydride, NaBH4, and lithium aluminum hydride, LiAlH4. The latter compound is a highly reactive, extremely powerful reducing agent. It is capable of reducing the carbonyl group in aldehydes, ketones, carboxylic acids, esters, amides, and acid halides. NaBH4 is a less reactive, more selective, reagent. It will convert aldehydes and ketones into alcohols, but it will not reduce carboxylic acids, esters, or amides. Equation 1 depicts the reduction of aldehydes and ketones by NaBH4 in general terms. The reaction involves addition of a hydride ion to the carbonyl carbon and transfer of a proton from the oxygen of the solvent to the

As mentioned above, the water content of the resin is less than 0.4% by weight. In preferred embodiments, the water content of not less than 0.3, 0.2 or 0.1% by weight. Resins invention has only a slight tendency to yellow when exposed to heat.

The latter compound is a highly reactive, extremely powerful reducing agent. It is capable of reducing the carbonyl group in aldehydes, ketones, carboxylic acids, esters, amides, and acid halides. NaBH4 is a less reactive, more selective, reagent.