A process for producing a polymer foam, comprising:
- i) preparing a mixture of polyisocyanate components, comprising:
- 10 to 100 wt % of a condensation product of at least one polyisocyanate component with at least one polycarboxylic acid having at least 3 COOH groups per molecule or its anhydride, the condensation product comprising polyimide groups;
- ii) reacting the mixture of polyisocyanate components with a polyol component and a polycarboxylic acid having two or more carboxyl groups in the presence of a Lewis base to obtain a polymer having a main chain comprising urethane, imide and amide groups;
- wherein
- carbon dioxide is released during the reaction ii),
- a foam stabilizer is optionally included in the reaction ii), and
- a content in weight % of the polyisocyanate mixture of i) in the reaction mixture ii) is from 35 to 65 wt %,
- a content of the polyol component in the reaction mixture ii) is from 5 to 50 wt %,
- a content of the polycarboxylic acid having two or more carboxyl groups in the reaction mixture ii) is from 1 to 59 wt %,
- a content of the Lewis Base in the reaction mixture ii) is from 0.01 to 3 wt %,
- a content of the foam stabilizer in the reaction mixture ii) is from 0 to 5 wt %, and a total of the wt % content values is 100%,
- and wherein
- the at least one polycarboxylic acid having at least 3 COOH groups per molecule or its anhydride is selected from the group consisting of 1,2,3-benzenetricarboxylic acid, 1,2,3-benzenetricarboxylic dianhydride, 1,3,5-benzenetricarboxylic acid (trimesic acid), 1,2,4-benzenetricarboxylic acid (trimellitic acid), trimellitic anhydride, 1,2,4,5-benzenetetracarboxylic acid (pyromellitic acid), 1,2,4,5-benzenetetracarboxylic dianhydride (pyromellitic dianhydride), 3,3′,4,4″-benzophenonetetracarboxylic acid, 3,3′,4,4″-benzo-phenonetetracarboxylic dianhydride, benzenehexacarboxylic acid (mellitic acid), anhydrides of mellitic acid, mellophanic acid, mellophanic anhydride, 1,2,3,4-benzenetetracarboxylic acid, 1,2,3,4-benzenetetracarboxylic dianhydride, 3,3,4,4-biphenyltetracarboxylic acid, 3,3,4,4-biphenyltetracarboxylic dianhydride, 2,2,3,3-biphenyltetracarboxylic acid, 2,2,3,3-biphenyltetracarboxylic dianhydride, 1,4,5,8-naphthalenetetracarboxylic acid, 1,4,5,8-naphthalenetetracarboxylic dianhydride, 1,2,4,5-naphthalenetetracarboxylic acid, 1,2,4,5-naphthalenetetracarboxylic dianhydride, 2,3,6,7-naphthalenetetracarboxylic acid, 2,3,6,7-naphthalenetetracarboxylic dianhydride, 1,4,5,8-decahydronaphthalenetetracarboxylic acid, 1,4,5,8-decahydronaphthalenetetracarboxylic dianhydride, 4,8-dimethyl-1,2,3,5,6,7-hexahydronaphthalene-1,2,5,6-tetracarboxylic acid, 4,8-dimethyl-1,2,3,5,6,7-hexahydronaphthalene-1,2,5,6-tetracarboxylic dianhydride, 2,6-dichloronaphthalene-1,4,5,8-tetracarboxylic acid, 2,6-dichloronaphthalene-1,4,5,8-tetracarboxylic dianhydride, 2,7-dichloronaphthalene-1,4,5,8-tetracarboxylic acid, 2,7-dichloronaphthalene-1,4,5,8-tetracarboxylic dianhydride, 2,3,6,7-tetrachloronaphthalene-1,4,5,8-tetracarboxylic acid, 2,3,6,7-tetrachloronaphthalene-1,4,5,8-tetracarboxylic dianhydride, 1,3,9,10-phenanethrenetetracarboxylic acid, 1,3,9,10-phenanthrenetetracarboxylic dianhydride, 3,4,9,10-perylenetetracarboxylic acid, 3,4,9,10-perylenetetracarboxylic dianhydride, bis(2,3-dicarboxyphenyl)methane, bis(2,3-dicarboxyphenyl)methane dianhydride, bis(3,4-dicarboxyphenyl)methane, bis(2,3-dicarboxyphenyl)methane dianhydride, bis(3,4-dicarboxyphenyl)methane, bis(3,4-dicarboxyphenyl)methane dianhydride, 1,1-bis(2,3-dicarboxyphenyl)methane, 1,1-bis(2,3-dicarboxyphenyl)ethane dianhydride, 1,1-bis(3,4-dicarboxyphenyl)ethane, 1,1-bis(3,4-dicarboxyphenyl)ethane dianhydride, 1,1-bis(3,4-dicarboxyphenyl)ethane, 1,1-bis(3,4-dicarboxyphenyl)ethane dianhydride, 2,2-bis(2,3-dicarboxyphenyl)propane, 2,2-bis(2,3-dicarboxyphenyl)propane dianhydride, 2,3-bis(3,4-dicarboxyphenyl)propane, 2,3-bis(3,4-dicarboxyphenyl)propane dianhydride, bis(3,4-carboxyphenyl) sulfone, bis(3,4-carboxyphenyl) sulfone dianhydride, bis(3,4-carboxyphenyl) ether, bis(3,4-carboxyphenyl) ether dianhydride, ethylenetetracarboxylic acid, ethylenetetracarboxylic dianhydride, 1,2,3,4-butanetetracarboxylic acid, 1,2,3,4-butanetetracarboxylic dianhydride, 1,2,3,4-cyclopentanetetracarboxylic acid, 1,2,3,4-cyclopentanetetracarboxylic dianhydride, 2,3,4,5-pyrrolidinetetracarboxylic acid, 2,3,4,5-pyrrolidinetetracarboxylic dianhydride, 2,3,5,6-pyrazinetetracarboxylic acid, 2,3,5,6-pyrazinetetracarboxylic dianhydride, 2,3,4,5-thiophenetetracarboxylic acid, 2,3,4,5-thiophenetetracarboxylic dianhydride and derivatives thereof.