Process for the production of polyisocyanate mixtures containing blocked isocyanate groups
AssigneeBayer Aktiengesellschaft
InventorsTilo Burkhardt, Manfred Schonfelder
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Abstract
This invention relates to a process for the production of new polyisocyanate mixtures containing blocked isocyanate groups, to binders containing these polyisocyanate mixtures and to the use of the new polyisocyanate mixtures as an isocyanate component in polyurethane stoving lacquers.
Claims23
A process for the production of polyisocyanate mixtures containing blocked isocyanate groups which are readily soluble in lacquer solvents, wherein polyhydroxyl compounds having a molecular weight in the range of from about 62 to 300 or mixtures of polyhydroxyl compounds having an average molecular weight of from about 62 to 300 are reacted with 3-isocyanato methyl-3,5,5-trimethyl cyclohexyl isocyanate to form a reaction mixture containing urethane groups and free isocyanate groups, the quantitative ratios between the reactants being selected in such a way that the reaction mixture contains from about 2 to 12 isocyanate groups per hydroxyl group, and the free isocyanate groups in the reaction mixture are blocked by reaction with blocking agents containing isocyanate-reactive methylene groups,
A process for the production of polyisocyanate mixtures containing blocked isocyanate groups which are soluble in lacquer solvents comprising reacting
- (a) polyhydroxyl compounds having a molecular weight of from about 62 to 300,
- (b) 3-isocyanato methyl-3,5,5-trimethyl cyclohexyl isocyanate wherein the NCO/OH equivalent ratio of (b) to (a) is from about 2 to 12, and
- (c) blocking agents containing isocyanate-reactive methylene groups, said blocking agents present in an amount from about 98 to 110% of the theoretical amount necessary to block the free isocyanate groups of reaction mixture (a) and (b) any.
A mixture which is storable at room temperature comprising
- (a) at least one polyhydroxyl compound having a molecular weight of from about 400 to 50,000, and
- (b) a polyisocyanate mixture containing blocked isocyanate groups comprising the reaction product of
- (i) polyhydroxyl compounds having a molecular weight of from about 62 to 300,
- (ii) 3-isocyanato methyl-3,5,5-trimethyl cyclohexyl isocyanate wherein the NCO/OH equivalent ratio of (ii) to (i) is from about 2 to 12, and
- (iii) blocking agents containing isocyanatereactive methylene groups, said blocking agents present in an amount from about 98 to 110% of the theoretical amount necessary to block the free isocyanate groups of reaction mixture (i) and (ii), wherein any unreacted monomeric diisocyanates are not removed, and
- wherein the equivalent ratio of hydroxyl groups in component (a) to the blocked isocyanate groups in component (b) is from about 0.8:1 to 1.6:1.
A process for the production of polyisocyanate mixtures containing blocked isocyanate groups which are readily soluble in lacquer solvents, wherein polyhydroxyl compounds having a molecular weight in the range of from about 62 to 300 or mixtures of polyhydroxyl compounds having an average molecular weight of from about 62 to 300 are reacted with 3-isocyanato methyl-3,5,5-trimethyl cyclohexyl isocyanate to form a reaction mixture containing urethane groups and free isocyanate groups, the quantitative ratios between the reactants being selected in such a way that the reaction mixture contains from about 2 to 12 isocyanate groups per hydroxyl group, and the free isocyanate groups in the reaction mixture are blocked by reaction with blocking agents containing isocyanate-reactive methylene groups, whereby the polyhydroxyl-isocyanate reaction and the blocking reaction are carried out simultaneously in one reaction vessel.
A process for the production of polyisocyanate mixtures containing blocked isocyanate groups which are soluble in lacquer solvents comprising reacting
- (a) polyhydroxyl compounds having a molecular weight of from about 62 to 300,
- (b) 3-isocyanato methyl-3,5,5-trimethyl cyclohexyl isocyanate wherein the NCO/OH equivalent ratio of (b) to (a) is from about 2 to 12,
- (c) blocking agents containing isocyanate-reactive methylene groups, said blocking agents present in an amount from about 98 to 110% of the theoretical amount necessary to block the free isocyanate groups of reaction mixture (a) and (b), and
- (d) catalytic amounts of organic alkali compounds.
A process for the production of polyisocyanate mixtures containing blocked isocyanate groups which are soluble in lacquer solvents comprising reacting simultaneously in one reaction vessel
- (a) polyhydroxyl compounds having a molecular weight of from about 62 to 300,
- (b) 3-isocyanato methyl-3,5,5-trimethyl cyclohexyl isocyanate wherein the NCO/OH equivalent ratio of (b) to (a) is from about 2 to 12, and
- (c) blocking agents containing isocyanate-reactive methylene groups, said blocking agents present in an amount from about 98 to 110% of the theoretical amount necessary to block the free isocyanate groups of reaction mixture (a) and (b).
Dependencies are inferred from the claim text.