Deformable, rigid polystyrene foam boards

Abstract

Provided are methods for producing a high strength, but easily deformed, polystyrene foam board that can endure repeatedly deformations from its original configuration into more complex curved shapes without damaging the board integrity or substantially reducing its structural strength. Also provided are rigid polystyrene foam boards produced by this method that exhibit improved bending and impact resistance while substantially retaining or improving other properties, for example, the thermal dimensional stability and fire resistance, exhibited by corresponding conventional XPS foam boards. The foamable compositions may incorporate one or more of a variety of polymer processing aids for the purpose of altering the performance of the final foam products, thereby allowing the properties of the final foam product to be customized to some degree.

1 . A method for producing expanded polystyrene foam products comprising: 
 preparing a pressurized foamable composition including a major portion of polystyrene, a first minor portion of bending agent and a second minor portion of blowing agent, wherein the bending agent is selected from at least one of vinyl acetate (EVA), polyvinylalcohol (PVA), vinyl alcohol/ethylene copolymer (EVOH), polyvinylidene chloride (PVDC), polyvinyl chloride (PVC), vinyl chloride/vinylidene chloride copolymer, vinylidene chloride/methylacrylate copolymer, polystyrene and polystyrene-containing ethylene oxide moieties and polymethyl methacrylate (PMMA);    extruding the pressurized foamable composition through a die into a region of lower pressure to form an intermediate foam product; and    cooling and finishing the intermediate foam product to form a final foam product.    
     
     
         2 . The method for producing expanded polystyrene foam products according to  claim 1 , wherein: 
 the bending agent is a vinyl alcohol/ethylene copolymer (EVOH).    
     
     
         3 . The method for producing expanded polystyrene foam products according to  claim 1 , wherein: 
 the bending agent is a vinyl alcohol/ethylene copolymer (EVOH) having a melt index from about 1.4 to about 1.8 at about 190° C. and an ethylene composition from about 30 to about 34 mol %.    
     
     
         4 . The method for producing expanded polystyrene foam products according to  claim 1 , wherein: 
 the bending agent is a vinyl alcohol/ethylene copolymer (EVOH) that represents less than about 10 wt. % of the foamable composition based on a dry weight of the foamed product.    
     
     
         5 . The method for producing expanded polystyrene foam products according to  claim 1 , wherein: 
 the bending agent is a vinyl alcohol/ethylene copolymer (EVOH) that represents no more than about 2.0 wt. % of the foamable composition based on a dry weight of the foamed product.    
     
     
         6 . The method for producing expanded polystyrene foam products according to  claim 1 , wherein: 
 the bending agent is a vinyl alcohol/ethylene copolymer (EVOH) or a PMMA that represents no more than about 3.5 wt. % of the foamable composition based on a dry weight of the foamed product.    
     
     
         7 . The method for producing expanded polystyrene foam products according to  claim 1 , wherein: 
 the bending agent is a vinyl alcohol/ethylene copolymers (EVOH) or PMMA and/or other additives that represents no more than about 0.5 wt. % of the foamable composition based on a dry weight of the foamed product.    
     
     
         8 . The method for producing expanded polystyrene foam products according to  claim 1 , wherein: 
 the pressurized foamable composition also includes a minor portion of an olefinic polymer or olefinic copolymer other than polystyrene.    
     
     
         9 . The method for producing expanded polystyrene foam products according to  claim 8 , wherein: 
 a majority. of the polar groups are hydroxyl groups.    
     
     
         10 . A rigid expanded polystyrene foam product comprising: 
 a major portion of polystyrene;    a first minor portion of a bending agent; and    a second minor portion of a blowing agent, wherein the first minor portion of bending agent includes at least one compound selected from at least one of vinyl acetate (EVA), polyvinylalcohol (PVA), vinyl alcohol/ethylene copolymer (EVOH), polyvinylidene chloride (PVDC), polyvinyl chloride (PVC), vinyl chloride/vinylidene chloride copolymer, vinylidene chloride/methylacrylate copolymer, polymethylmethacrylate (PMMA); and    the second minor portion of blowing agent includes at least one compound selected from at least one of HCFCs, HFCs, CO 2 , H 2 O, inert gases, alcohols, dimethyl ether (DME), hydrocarbons and mixtures thereof, and    wherein a transverse sample has a nominal thickness of about 1 inch (about 2.54 cm) has a radius a Test A failure radius R f  of less than about 12 inches.    
     
     
         11 . The rigid expanded polystyrene foam product according to  claim 10 , further including: 
 a third minor portion of one or more polymers and copolymers compatible with the major portion of polystyrene, and wherein    the first minor portion of the bending agent is a blend of at least two bending agents, and further wherein    the second minor portion of the blowing agent is a blend of at least two blowing agents.    
     
     
         12 . The rigid expanded polystyrene foam product according to  claim 10 , wherein: 
 the bending agent is a vinyl alcohol/ethylene copolymer (EVOH).    
     
     
         13 . The rigid expanded polystyrene foam product according to  claim 10 , wherein: 
 the bending agent is a vinyl alcohol/ethylene copolymer (EVOH) having a melt index from about 1.4 to about 1.8 at about 190° C.    
     
     
         14 . The rigid expanded polystyrene foam product according to  claim 10 , wherein: 
 the bending agent is a vinyl alcohol/ethylene copolymer (EVOH) having a melt index from about 1.4 to about 1.8 at about 190° C. and an ethylene composition from 30 to 34 mol %.    
     
     
         15 . The rigid expanded polystyrene foam product according to  claim 10 , wherein: 
 the bending agent is a vinyl alcohol/ethylene copolymer (EVOH) and /or PMMA or other additives that represents no more than about 2.5 wt. % of the foamable composition based on a dry weight of the foamed product.    
     
     
         16 . The rigid expanded polystyrene foam product according to  claim 10 , wherein: 
 the bending agent is a vinyl alcohol/ethylene copolymer (EVOH) and/or PMMA or other additives that represents no more than about 1.0 wt. % of the foamable composition based on a dry weight of the foamed product.    
     
     
         17 . The rigid expanded polystyrene foam product according to  claim 16 , wherein: 
 the bending agent is a vinyl alcohol/ethylene copolymer (EVOH) and/or PMMA or other additives that represents no more than about 2.5 wt. % of the foamable composition based on a dry weight of the foamed product and wherein a transverse sample has a nominal thickness of about 1 inch (about 2.54 cm) has an R f  of less than about 6 inches.    
     
     
         18 . The rigid expanded polystyrene foam product according to  claim 16 , wherein: 
 the bending agent is a vinyl alcohol/ethylene copolymer (EVOH) and/or PMMA or other additives that represents no more than about 3.5 wt. % of the foamable composition based on a dry weight of the foamed product and wherein a transverse sample has a nominal thickness of about 1 inch (about 2.54 cm) has an R f  of less than about 4 inches.    
     
     
         19 . The rigid expanded polystyrene foam product according to  claim 16 , wherein: 
 the bending agent is a vinyl alcohol/ethylene copolymer (EVOH) and/or PMMA or other additives that represents no more than about 2.5 wt. % of the foamable composition based on a dry weight of the foamed product and wherein a transverse sample has a nominal thickness of about 1 inch (about 2.54 cm) has an R f  of less than about 4 inches and a critical radius R c  of less than about 12 inches (about 30.5 cm) measured according to Test procedure A.    
     
     
         20 . The rigid expanded polystyrene foam product according to  19 , wherein: 
 the polystyrene foam product has a nominal thickness of about 1 inch (about 2.54 cm) has an R f  of less than about 4 inches and a critical radius R c  of less than about 6 inches (about 15.2 cm) measured according to Test procedure B.