Patent GB-777997-A (GB)
Title: Modified polysiloxanes and method of preparing same
Filed: 1955-04-13
Abstract: Certain organopolysiloxanes are modified by reacting them at 140 DEG to 250 DEG  C. with certain bis-(hydroxyalkyl) dicarboxylates until the desired amount of alcohol has been evolved by transesterification.  The siloxanes used have (a) a molecular weight of 400 to 4000; (b) 1.0 to 1.6 silicon-bonded phenyl or phenyl and methyl radicals per Si atom, 0 to 40 per cent of the hydrocarbon radicals being methyl; and (c) 5 to 40 per cent by weight of the siloxane of silicon-bonded alkoxy and/or aryloxy radicals, and are made in known manner.  The dicarboxylates used contain 8 to 18 carbon atoms of which 2 to 4 belong to the hydroxy-alkyl portion, and may be made by complete esterification of a dicarboxylic acid or anhydride containing 4 to 10 carbon atoms with an aliphatic dihydric alcohol containing 2 to 4 carbon atoms (see Group IV (b)).  Diester-forming reactants specified are ethylene, 1.2-propylene, 1.3-propylene, diethylene and butylene glycols; succinic, glutaric, adipic, pimelic, azelaic, sebacic, maleic, phthalic, terephthalic, endoalkylene phthalic, nitrophthalic, chlorophthalic and hexachloroendomethylenetetrahydrophthalic acids and anhydrides thereof.  The polymers are made by reacting stoichiometric amounts of the reactants in the presence or absence of a solvent.  Curing agents, e.g. phenol-, urea- and melamine-formaldehyde resins, glycerol or pentaerythritol may be added, e.g. in amount of 5 to 20 per cent by weight of the polymer.  In examples a phenyl ethoxypolysiloxane is reacted with (1, 7 to 11) bis-(b -hydroxyethyl) orthophthalate, (2) bis-(b -hydroxyethyl)-3-nitrophthalate, (3) bis-(b -hydroxyethyl) orthophthalate in the presence of glycerol, and (4) bis-(b -hydroxyethyl) tetrachlorophthalate in the presence of glycerol; a phenylmethylethoxy siloxane resin is reacted with (5,6) bis-(b -hydroxyethyl) orthophthalate, (12) bis-(b -hydroxyethyl) terephthalate, and (13) bis - (hydroxyethyl) chlorendate.  The products in solution in solvents, e.g. xylene or toluene, and with or without pigments, e.g. titania, are used for coating, e.g. glass cloth, steel panels and copper wires.ALSO:Bis-(hydroxyalkyl) dicarboxylates containing 8 to 18 carbon atoms of which 2 to 4 belong to the hydroxyalkyl portion may be made by completely esterifying a dicarboxylic acid or anhydride thereof containing 4 to 10 carbon atoms with an aliphatic dihydric alcohol containing 2 to 4 carbon atoms, polyester formation being inhibited by using the alcohol in amount in excess of that required for the complete esterification. Thus, bis - (b  - hydroxy ethyl) orthophthalate is made by reacting 1 mol. of phthalic anhydride with 2 mols. of ethylene glycol at 120 DEG to 200 DEG  C. and adding further glycol during the reaction.  In Example 13, ethylene glycol is reacted with chlorendic acid (1.4.5.6.7.7 - hexachlorobicyclo - [2.2.1] - 5 - heptene-2.3-dicarboxylic acid) to give bis-(b -hydroxyethyl) chlorendate.  Other diester-forming reactants specified are: 1.2-propylene, 1.3 - propylene-, diethylene- and butylene - glycols; succinic, glutaric, adipic, pimelic, azelaic, sebacic, maleic, phthalic, terephthalic, endoalkylenephthalic, nitrophthalic, chlorophthalic and hexachloroendomethylenetetrahydrophthalic acids and anhydrides thereof.