Flexible polyurethane foam and process for its production

Abstract

To provide a flexible polyurethane foam having improved sound absorbing properties in a low frequency region. A process for producing a flexible polyurethane foam which comprises foaming a starting material composition (E) comprising a high molecular weight polyoxyalkylene polyol (A), an organic polyisocyanate compound (B), a blowing agent (C) and a catalyst (D) in a closed mold, characterized in that at least a part of the high molecular weight polyoxyalkylene polyol (A) is a polyoxyalkylene polyol (p) having at least two hydroxyl groups on the average and having a molecular weight (Mc) per hydroxyl group of from 1,800 to 2,800 and a total unsaturation value (USV) of at most 0.08 meq/g, and that the air flowability of a flexible polyurethane foam obtained by foaming the starting material composition (E) in a thickness of 26 mm, is at most 0.085 m 3 /min.

1 . A process for producing a flexible polyurethane foam which comprises foaming a starting material composition (E) comprising a high molecular weight polyoxyalkylene polyol (A), an organic polyisocyanate compound (B), a blowing agent (C) and a catalyst (D) in a closed mold, characterized in that at least a part of the high molecular weight polyoxyalkylene polyol (A) is a polyoxyalkylene polyol (p) having at least two hydroxyl groups on the average and having a molecular weight (Mc) per hydroxyl group of from 1,800 to 2,800 and a total unsaturation value (USV) of at most 0.08 meq/g, and that the air flowability of a flexible polyurethane foam obtained by foaming the starting material composition (E) in a thickness of 26 mm, is at most 0.085 m 3 /min.  
   
   
       2 . The process for producing a flexible polyurethane foam according to  claim 1 , wherein in a sound absorption measuring method by a vertical entry method of a flexible polyurethane foam obtained by foaming the starting material composition (E) in a thickness of 26 mm, the sound absorption characteristic at 500 Hz is at least 0.3, and the sound absorption characteristic at 2,000 Hz is at least 0.55.  
   
   
       3 . The process for producing a flexible polyurethane foam according to  claim 1 , wherein the density of the flexible polyurethane foam is at most 120 kg/m 3 .  
   
   
       4 . The process for producing a flexible polyurethane foam according to  claim 1 , wherein the high molecular weight polyoxyalkylene polyol (A) has at least two hydroxyl groups on the average and has a molecular weight (Mc) per hydroxyl group of from 500 to 5,000.  
   
   
       5 . The process for producing a flexible polyurethane foam according to  claim 1 , wherein the proportion of the polyol (p) in the high molecular weight polyoxyalkylene polyol (A) is from 5 to 100 mass %.  
   
   
       6 . The process for producing a flexible polyurethane foam according to  claim 1 , wherein the polyol (p) is a polyoxyalkylene polyol obtained by ring opening addition polymerization of an alkylene oxide in the presence of a composite metal cyanide complex catalyst or a cesium hydroxide catalyst, and an initiator.  
   
   
       7 . The process for producing a flexible polyurethane foam according to  claim 1 , wherein the blowing agent is one blowing agent selected from water and an inert gas.  
   
   
       8 . A flexible polyurethane foam for soundproofing material obtained by the process as defined in  claim 1 .  
   
   
       9 . A flexible polyurethane foam for automobile interior material obtained by the process as defined in  claim 1.