Pvc membrane with reduced plasticizer migration

Abstract

The invention relates to a membrane including a partition layer, wherein the partition layer contains at least 50 wt % of PVC, and a barrier layer. The barrier layer can be a barrier layer, wherein the barrier layer has a polyamide layer containing more than 50 wt % of copolymer, wherein said polyamide layer is connected to the partition layer by a polyurethane layer, wherein the polyurethane layer contains more than 10 wt % of polyurethane. Alternatively, the barrier layer can be a barrier layer, wherein the barrier layer is made of a composition containing 5-50 wt % of polyurethane and 50-95 wt % of copolymer. The membranes according to the invention have significantly lower plasticizer migration compared to the membranes of the prior art and are characterized by improved aging resistance, in particular with regard to the adhesion of the barrier layer to the partition layer, and impermeability to moisture.

What is claimed: 
     
         1 . A method for producing a membrane, comprising a sealing layer, wherein the sealing layer consists more than 50% by weight of PVC, relative to the total weight of the sealing layer, and a barrier layer S 2 , wherein the barrier layer S 2  consists of a composition comprising 5-50% by weight polyurethane PUR and 50-95% by weight copolymer PA, comprising the steps:
 (i) applying a composition Z 1  comprising polyurethane PUR, copolymer PA and solvent onto a sealing layer; and 
 (ii) flashing off the composition Z 1  while forming a barrier layer S 2 , wherein 
 the copolymer PUR has at least one nucleophilic functional group, which is selected from the group consisting of hydroxyl group, carboxyl group, sulfonate group and phosphate group, and wherein the copolymer PA is a copolymer of aliphatic diamine with 4-10 C atoms, dicarboxylic acid with 4-10 C atoms, cycloaliphatic diamine with 6-20 C atoms, and a compound selected from the group consisting of aliphatic lactam with 4-10 C atoms and alpha, omega-amino carboxylic acids with 2-20 C atoms. 
 
     
     
         2 . The method according to  claim 1 , wherein the application of the composition Z 1  in Step (i) is performed by applying the composition Z 1  in the liquid state. 
     
     
         3 . The method according to  claim 1 , wherein flashing-off of the composition Z 1  in Step (ii) is performed for 1-5 minutes at 100-170° C. 
     
     
         4 . The method according to  claim 1 , wherein the proportion of the sum of polyurethane PUR together with copolymer PA is 1-30% by weight, relative to the total weight of the composition Z 1 .