Process for producing flame-retardant porous materials based on polyurea

Abstract

The present invention relates to a process for producing flame-retardant porous materials comprising the following steps: (a) reacting at least one polyfunctional isocyanate (a1) and at least one polyfunctional aromatic amine (a2) in an organic solvent optionally in the presence of water as component (a3) and optionally in the presence of at least one catalyst (a5); and then (b) removing the organic solvent to obtain the organic porous material, where step (a) is carried out in the presence of at least one organic flame retardant as component (a4), where this flame retardant is soluble in the solvent. The invention further relates to the porous materials thus obtainable, and also to the use of the porous materials for thermal insulation.

1 . A process for producing porous materials comprising the following steps:
 (a) reacting at least one polyfunctional isocyanate (a1) and at least one polyfunctional aromatic amine (a2) in an organic solvent optionally in the presence of water as component (a3) and optionally in the presence of at least one catalyst (a5); and then   (b) removing the organic solvent to obtain the organic porous material, where step (a) is carried out in the presence of at least one organic flame retardant as component (a4), where this flame retardant is soluble in the solvent.   
     
     
         2 . The process according to  claim 1 , where the flame retardants of component (a3) are compounds comprising phosphorus and/or halogen, in particular bromine. 
     
     
         3 . The process according to  claim 1  or  2 , where the amounts used as component (a4) are from 0.1 to 25% by weight, preferably from 1 to 15% by weight, based in each case on the amount by weight of components (a1) to (a4), which is 100% by weight. 
     
     
         4 . The process according to one or more of  claims 1  to  3 , where component (a4) comprises at least one flame retardant selected from the group consisting of polybrominated compounds and of organophosphorus compounds. 
     
     
         5 . The process according to one or more of  claims 1  to  4 , where component (a4) comprises at least one organophosphoric acid derivative. 
     
     
         6 . The process according to one or more of  claims 1  to  5 , where component (a4) comprises at least one organophosphonic acid derivative. 
     
     
         7 . The process according to one or more of  claims 1  to  6 , where component (a4) comprises at least one organophosphinic acid derivative. 
     
     
         8 . The process according to one or more of  claims 1  to  7 , where component (a4) comprises at least one compound which comprises a functional group reactive toward isocyanates, in particular at least 2 such reactive functional groups. 
     
     
         9 . The process according to one or more of  claims 1  to  8 , where the at least one polyfunctional isocyanate (a1) is composed of at least one polyfunctional isocyanate selected from diphenylmethane 4,4′-diisocyanate, diphenylmethane 2,4′-diisocyanate, diphenylmethane 2,2′-diisocyanate, and oligomeric diphenylmethane diisocyanate. 
     
     
         10 . The process according to one or more of  claims 1  to  9 , where component (a1) comprises oligomeric diphenylmethane diisocyanate and its functionality is at least 2.4. 
     
     
         11 . The process according to one or more of  claims 1  to  10 , where component (a2) comprises oligomeric diaminodiphenylmethane and its functionality is at least 2.4. 
     
     
         12 . The process according to one or more of  claims 1  to  11 , where the at least one polyfunctional aromatic amine comprises at least one polyfunctional aromatic amine of the general formula I 
       
         
           
           
               
               
           
         
       
       where R 1  and R 2  can be identical or different and are selected mutually independently from hydrogen and linear or branched alkyl groups having from 1 to 6 carbon atoms, and where all of the substituents Q 1  to Q 5  and Q 1  to Q 5 ′ are identical or different and are selected mutually independently from hydrogen, a primary amino group, and a linear or branched alkyl group having from 1 to 12 carbon atoms, where the alkyl group can bear further functional groups, with the proviso that the compound of the general formula I comprises at least two primary amino groups, where at least one of Q 1 , Q 3 , and Q 5  is a primary amino group, and at least one of Q 1 ′, Q 3 ′, and Q 5 ′ is a primary amino group. 
     
     
         13 . The process according to  claim 12 , where Q 2 , Q 4 , Q 2 ′, and Q 4 ′ are selected in such a way that the compound of the general formula I has at least one linear or branched alkyl group which can bear further functional groups and which has from 1 to 12 carbon atoms in α-position with respect to at least one primary amino group bonded to the aromatic ring. 
     
     
         14 . The process according to one or more of  claims 1  to  13 , where component (a2) comprises at least one of the following compounds: 4,4′-diaminodiphenyl-methane, 2,4′-diaminodiphenylmethane, 2,2′-diaminodiphenylmethane, and oligomeric diaminodiphenylmethane. 
     
     
         15 . The process according to one or more of  claims 1  to  14 , where the reaction takes place in the presence of a catalyst (a5). 
     
     
         16 . The process according to one or more of  claims 1  to  15 , where the removal of the solvent takes place via conversion of the solvent to the gaseous state at a temperature and a pressure below the critical temperature and the critical pressure of the solvent. 
     
     
         17 . A porous material obtainable according to  claims 1  to  16 . 
     
     
         18 . The porous material according to  claim 17 , where the volume-average pore diameter of the xerogel is at most 5 micrometers. 
     
     
         19 . The use of the porous material according to  claim 17  or  18  for thermal insulation. 
     
     
         20 . The use of the porous material according to  claim 17  or  18  for thermal insulation in construction applications.