Methoxy-functional organopolysiloxanes, their preparation and use
OwnerGerhard Reusmanninventor
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Abstract
The invention relates to methoxy-functional organopolysiloxanes having a narrow molecular weight distribution with an average molecular weight (MW)≦2000 g/mol and of the general formula 1 where R1 is a methyl group, R2 denotes different radicals, comprising the phenyl radical and alkyl radicals having 1 to 4 carbon atoms, a is from 1 to 1.7 and b≦1, at least 80% of the polysiloxane having a molecular weight between 800 and 2000 g/mol, to a process for their preparation and to their use as coating constituents in corrosion protection coatings.
Claims10
A methoxy-functional organopolysiloxane having a narrow molecular weight distribution with an average molecular weight (MW)≦about 2000 g/mol and of the general formula
- 5
- where
- R1 is a methyl group,
- R2 independently is an phenyl radical or an alkyl radical,
- a is from 1 to 1.7 and
- b≦1,
- wherein
- at least 80% of the polysiloxanes have an average molecular weight of between about 800 and about 2000 g/mol.
A process for preparing a methoxy-functional organopolysiloxane as claimed in claim which comprises:
- 1. selecting one or more different silanes of the formula
- R2SiX3,
- and, optionally,
- R2SiX2, 6
- R3O[R22SiO—]nR3, (R2)3SiX, (R3)3Si—O—Si—(R2)3,
- or a hydrolyslate thereof
- wherein
- X is a hydrolysable group,
- R2 and R3 independently are alkyl or phenyl groups, and
- n is from 1 to 500
- and determining which of the one or more different silanes is the most reactive out of those selected;
- 2. reacting the silane with the most reactivity with methanol and water to the extent that from 1 to 2 equivalents fo the hydrolyzable groups X are reacted per molecule.
- 3. adding the one or more of the less reactive silanes to the reaction mixture and further reacting this mixture with methanol and water.
Dependencies are inferred from the claim text.