Irrigation device

Abstract

The present invention relates to irrigation systems for irrigating a growing medium. The irrigation systems of the invention comprise a helical tubular hydrophilic membrane or a corrugated tubular hydrophilic membrane. The invention also relates to methods of irrigating a growing medium, and helical tubular hydrophilic membranes for use in an irrigation system.

What is claimed is: 
     
         1 . An irrigation system comprising a non-helical corrugated tubular hydrophilic membrane buried in a growing medium. 
     
     
         2 . An irrigation system according to  claim 1  comprising a tubular hydrophilic membrane buried in a growing medium. 
     
     
         3 . The irrigation system according to  claim 2  wherein said hydrophilic membrane is coated on or adhered to a support material. 
     
     
         4 . The irrigation system according to  claim 3  wherein said hydrophilic membrane comprises a hydrophilic polymer having a water vapour transmission rate according to ASTM E96-95 (Procedure BW) of at least 400 g/m 2 /24 h, measured using air at 23° C. and 50% relative humidity at a velocity of 3 m/s on a film of total thickness 25 microns. 
     
     
         5 . The irrigation system according to  claim 4  wherein said hydrophilic membrane comprises a copolyetherester elastomer or a mixture of two or more copolyetherester elastomers; a polyether-block-polyamide or a mixture of two or more polyether-block-polyamides; a polyether urethane or a mixture of two or more polyether urethanes; or a homopolymer or copolymer of polyvinyl alcohol or a mixture of two or more homopolymers or copolymers of polyvinyl alcohol. 
     
     
         6 . The irrigation system according to any one of  claims 1  to  6  wherein said hydrophilic membrane comprises a copolyetherester elastomer or mixture of two or more copolyetherester elastomers having a multiplicity of recurring long-chain ester units and short-chain ester units joined head-to-tail through ester linkages, where the long-chain ester units are represented by the formula: 
       
         
           
           
               
               
           
         
         and said short-chain ester units are represented by the formula: 
       
       
         
           
           
               
               
           
         
         wherein:
 a) G is a divalent radical remaining after the removal of terminal hydroxyl groups from a poly(alkylene oxide)glycol having a number average molecular weight of about 400-4000; 
 b) R is a divalent radical remaining after removal of carboxyl groups from a dicarboxylic acid having a molecular weight less than 300; 
 c) D is a divalent radical remaining after removal of hydroxyl groups from a diol having a molecular weight less than about 250; optionally 
 d) the copolyetherester contains 0-68 weight percent based on the total weight of the copolyetherester, ethylene oxide groups incorporated in the long-chain ester units of the copolyetherester; and 
 e) the copolyetherester contains about 25-80 weight percent short-chain ester units. 
 
       
     
     
         7 . The irrigation system according to  claim 6  wherein said hydrophilic membrane comprises a copolyetherester elastomer having water vapour transmission rate according to ASTM E96-95 (Procedure BW) of more than 400 g/m 2 /24 h measured on a film thickness of 25 microns using air at 23° C. and 50% relative humidity at a velocity of 3 m/s.