Process for producing polyisocvanurate plastics having functionalized surfaces
The invention relates to a process for producing polyisocyanurate plastics having a functionalized surface, comprising the following steps: a) providing a polyisocyanate composition A) containing monomeric and/or oligomeric polyisocyanates; b) catalytically trimerizing the polyisocyanate composition A) so as to obtain a bulk polyisocyanurate material as intermediate; c) surface functionalizing the intermediate by contacting at least one surface of the intermediate with at least one functionalizing reagent D); d) continuing the catalytic trimerization. The invention further relates to a polyisocyanurate plastic having a functionalized surface obtainable from the process of the invention.
1. A process for producing polyisocyanurate plastics having a functionalized surface, comprising the following steps:
a) providing a polyisocyanate composition A) containing monomeric and/or oligomeric polyisocyanates;
b) catalytically trimerizing the polyisocyanate composition A) so as to obtain a bulk polyisocyanurate material as intermediate;
c) surface functionalizing the intermediate by contacting at least one surface of the intermediate with at least one functionalizing reagent D);
d) continuing the catalytic trimerization.
2. The process according to claim 1 , wherein the catalytic trimerization in step b) is continued until a viscosity of at least 100000 mPas or the gel point has been attained.
3. The process according to claim 1 , wherein the catalytic trimerization in step b) is effected up to a conversion level at which more than 20% of isocyanate groups originally present in the polyisocyanate composition A) are present.
4. The process according to claim 1 , wherein the continuation of the catalytic trimerization in step d) is effected up to a conversion level at which only at most 20% of isocyanate groups originally present in the polyisocyanate composition A) are present.
5. The process according to claim 1 , wherein the contacting in step c) is effected by flow coating, dipping, spraying, printing, pipetting, roller coating, bar coating, scattering, vapour deposition or painting.
6. The process according to claim 1 , wherein excess functionalizing reagent D) is removed between steps c) and d).
7. The process according to claim 1 , wherein the functionalizing reagent D) is selected from the group consisting of compounds containing alcohol, thiol, amine, epoxide, anhydride, organic acid, isocyanate groups and mixtures thereof.
8. The process according to claim 1 , wherein the polyisocyanate composition A) contains predominantly oligomeric polyisocyanates and is low in monomeric polyisocyanates wherein said low in monomeric polyisocyanates wherein the polyisocyanate composition A) has a content of monomeric polyisocyanates of not more than 20% by weight, based on the weight of the polyisocyanate composition A).
9. Process according to claim 8 , wherein the polyisocyanate composition A) has a content of monomeric polyisocyanates of not more than 15% by weight, based on the weight of the polyisocyanate composition A).
10. Process according to claim 8 , wherein the polyisocyanate composition A) has a content of monomeric polyisocyanates of not more than 5% by weight, based on the weight of the polyisocyanate composition A).
11. The process according to claim 1 , wherein the polyisocyanate composition A) has an isocyanurate structure content of at least 20 mol %, based on the sum total of the oligomeric structures from the group consisting of uretdione, isocyanurate, allophanate, biuret, iminooxadiazinedione and oxadiazinetrione structure present in the polyisocyanate composition A).
12. The process according to claim 1 , wherein the polyisocyanate composition A) consists of at least 80% by weight, based on the weight of the polyisocyanate composition A), of monomeric diisocyanates having exclusively aliphatically bonded isocyanate groups.
13. The process according to claim 1 , wherein the polyisocyanate composition A) consists of at least 95% by weight, based on the weight of the polyisocyanate composition A), of monomeric diisocyanates having exclusively aliphatically bonded isocyanate groups.
14. The process according to claim 1 , wherein the oligomeric polyisocyanates consist of one or more oligomeric polyisocyanates formed from 1,4-diisocyanatobutane, 1,5-diisocyanatopentane, 1,6-diisocyanatohexane, isophorone diisocyanate or 4,4′-diisocyanatodicyclohexylmethane or mixtures thereof, and/or in that the monomeric polyisocyanates consist of one or more monomeric diisocyanates selected from 1,4-diisocyanatobutane, 1,5-diisocyanatopentane, 1,6-diisocyanatohexane, isophorone diisocyanate or 4,4′-diisocyanatodicyclohexylmethane or mixtures thereof.
15. The process according to claim 1 , wherein the polyisocyanate composition A) has a mean NCO functionality of 2.0 to 5.0 or the polyisocyanate composition A) has a content of reactive isocyanate groups of 8% to 60% by weight, based on the weight of the polyisocyanate composition A).
16. The process according to claim 1 , wherein the oligomeric polyisocyanates are selected from at least one oligomeric polyisocyanate having uretdione, isocyanurate, allophanate, biuret, iminooxadiazinedione or oxadiazinetrione structure or mixtures thereof.
17. A solid polyisocyanurate plastic having a functionalized surface obtainable from the process according to claim 1 , wherein the functionalizing agent D) has at least one isocyanate-reactive group per molecule, and wherein the catalytic trimerization in step b) continues until a viscosity of at least 100000 mPas is reached.