Straw mats for soil erosion control

Abstract

Straw mats useful for covering soil to prevent wind and rain erosion are made by randomly distributing straw into a layer and binding the stalks together at their points of contact with at least about 75 pounds per ton of straw of a water resistant adhesive comprising a polymer of an alkenyl aromatic monomer, an open chain conjugated diene and an unsaturated carboxylic monomer blended with a water soluble cellulose ether and with an organo sulfonate.

What is claimed is: 
     
       1. A coherent air and moisture permeable straw mat for covering soil to prevent wind and rain erosion thereof, said mat comprising straw stalks distributed randomly into a layer with the stalks adhered together at their points of contact with each other with at least 75 pounds per ton of straw of a water resistant adhesive consisting essentially of (1) an interpolymer of less than 60 weight percent of an alkenyl aromatic monomer, wherein an alkenyl group is attached directly to an aromatic nucleus, at least 40 weight percent of an open chain conjugated diolefin having from 4 to about 9 carbon atoms, and an unsaturated carboxylic acid or anhydride, (2) from about 0.5 to 2.5 weight percent based on polymer solids of a water soluble cellulose ether and (3) from about 0.7 to 2.5 weight percent of a water-soluble organo sulfonate having at least one sulfonate group attached to an aromatic ring and represented by the formula:   R--[ArSO.sub.3 ]M     wherein R is an alkyl chain having from about 8 to 20 carbon atoms .Iadd., an alkenyl chain having from about 8 to 20 carbon atoms .Iaddend.and combinations of said chains with ethoxy chains, phenyl, phenoxy and alkyl or alkoxy substituted phenyl or phenoxy: Ar is phenyl or naphthyl and M is an alkali metal or ammonia.   
     
     
       2. The straw mat of claim 1 wherein said interpolymer is composed of styrene, butadiene, acrylic acid and maleic anhydride. 
     
     
       3. The straw mat of claim 2 wherein said interpolymer is composed of about 36.5 weight percent styrene, about 60 weight percent butadiene, about 2 weight percent acrylic acid and about 1.5 weight percent maleic anhydride. 
     
     
       4. The straw mat of claim 1 wherein said interpolymer is composed of styrene, butadiene and itaconic acid. 
     
     
       5. The straw mat of claim 1 wherein said interpolymer is composed of about 48 weight percent styrene, about 50 weight percent butadiene and about 2 weight percent itaconic acid. 
     
     
       6. The straw mat of claim 1 wherein said water soluble cellulose ether is hydroxypropyl methyl cellulose. 
     
     
       7. The straw mat of claim 1 wherein said organo sulfonate is sodium dodecylphenoxy benzene sulfonate. 
     
     
       8. A method for making a wind and rain resistant straw mat comprising the blending of straw with at least 75 pounds per ton of straw of a water resistant adhesive, consisting essentially of (1) an interpolymer of less than 60 weight percent of an alkenyl aromatic monomer wherein an alkenyl group is attached directly to an aromatic nucleus, at least 40 weight percent of an open chain conjugated diolefin having from 4 to about 9 carbon atoms, and an unsaturated carboxylic acid or anhydride (2) from about 0.5 to 2.5 weight percent based on polymer solids of a water soluble cellulose ether and (3) from about 0.70 to 2.5 weight percent of a water-soluble organo sulfonate having at least one sulfonate group attached to an aromatic ring and represented by the formula:   R [Ar -- SO.sub.3 ]M     wherein R is an alkyl chain having from about 8 to 20 carbon atoms, an alkenyl chain having from about 8 to 20 carbon atoms and combinations of said chains with ethoxy chains, phenyl, phenoxy, and alkyl or alkoxy substituted phenyl or phenoxy:   Ar is phenyl or naphthyl and M is an alkali metal or ammonia, distributing the coated straw randomly into a layer, and drying the adhesive.