Binders and a method of use thereof as coating material for metal containers
View Patent ↗Condensation products of dihydroxyaromatics A, alone or in mixture with mono- or polyhydroxyaromatics C, with diepoxides or polyepoxides B which have been alkylolated by reaction with aldehydes D and whose alkylol groups may have been etherified with alcohols, a process for preparing them, and a method of use thereof in particular as compositions for coating the inside of foodstuff and beverage packaging forms made from metals.
1. Condensation products of dihydroxyaromatics A with polyepoxides B where the polyepoxides B are selected from the group consisting of polyglycidyl ethers of polyhydric alcohols with a specific epoxide group content of from 0.5 mol/kg to 6.7 mol/kg, which condensation products have been alkylolated by reaction with aldehydes D, wherein the amount of substance of phenolic OH groups in A to the amount of substance of epoxide groups in B is greater than 1 mol/mol, and wherein at least some of the alkylol groups introduced by reaction with the aldehydes D have been etherified with alcohols E.
2. Condensation products as claimed in claim 1 , wherein at least some of the alkylol groups introduced by the reaction with the aldehydes D have been etherified with alcohols E which alcohols are selected from the group consisting of methanol, n-butanol, and iso-butanol.
3. Binders obtained by condensation, in the first step, of dihydroxyaromatics A with polyepoxides B selected from the group consisting of polyglycidyl ethers of polyhydric alcohols with a specific epoxide group content of from 0.5 mol/kg to 6.7 mol/kg, in a ratio of the amount of substance of phenolic OH groups in A to the amount of substance of epoxide groups in B of greater than 1 mol/mol to form a condensation product, alkylolation of the said condensation product by reaction with aldehydes D in the second step, such that the reaction product formed contains free alkylol groups, wherein the amount of substance of aldehyde D to the sum of the amounts of substance of terminal phenolic OH groups in the condensation product of the first step is from 1 mol/mol to 3 mol/mol, and reaction in the third step with alcohols E to yield alkylol ethers.