Base material for laminate and process for producing the same

Abstract

The present invention is to provide a base material for a laminate having a high strength, reduced thickness, and light weight. In the present invention, a base material is prepared by incorporating a thermosetting resin binder into a non-woven fabric of para-aramid fibers prepared by a wet type paper making, and then heating a plurality of the resultant non-woven fabric sheets under pressure. The non-woven fabric sheet comprises 95 to 70 mass % of the para-aramid fibers and 5 to 30 mass % of the thermosetting resin binder.

What is claimed is:  
     
         1 . A base material for a laminate comprising a plurality of non-woven fabric sheets which are heated under pressure so that they are integrated, said non-woven fabric sheet comprising (1) a non-woven fabric constituted of para-aramid fibers and prepared by wet type paper-making process and (2) a thermosetting resin binder incorporated into said non-woven fabric, said non-woven fabric sheet composed of 95 to 70 mass % of said para-aramid fibers and 5 to 30 mass % of said thermosetting resin binder based on the total mass of said para-aramid fibers and said thermosetting resin binder.  
     
     
         2 . The base material of  claim 1 , further containing 3 to 300 mass %, based on the total mass of said para-aramid fibers and said thermosetting resin binder, of thermoplastic resin fibers having a softening point of 220° C. or higher and/or thermosetting resin fibers having a glass transition temperature of 120° C. or higher.  
     
     
         3 . The base material of  claim 1 , wherein said non-woven fabric sheet is in a wet state where it is not dried.  
     
     
         4 . The base material of  claim 1 , wherein said non-woven fabric sheet is dried.  
     
     
         5 . The base material of  claim 4 , wherein said non-woven fabric sheet is dried by heating it at 105 to 220° C.  
     
     
         6 . A base material for a laminate comprising a plurality of non-woven fabric sheets which are heated under pressure so that they are integrated, said non-woven fabric sheet comprising (1) a non-woven fabric constituted of para-aramid fibers and prepared by wet type paper making process and (2) a thermosetting resin binder incorporated into said non-woven fabric, said non-woven fabric sheet being dried by heat and a plurality of said non-woven fabric sheets being heated under pressure at a temperature of 30° or higher than said drying temperature and up to 400° C.  
     
     
         7 . The base material of  claim 6 , wherein a plurality of said non-woven fabric sheets are heated at 200° C. or higher.  
     
     
         8 . The base material of  claim 6 , wherein said heating is carried out by a pair of heated rolls.  
     
     
         9 . A process for producing a base material for a laminate comprising the steps of: 
 1) incorporating a thermosetting resin binder into a non-woven fabric prepared by a wet type paper making process and constituted of para-aramid fibers, to prepare a non-woven fabric sheet; and    2) heating a plurality of said non-woven fabric sheets under pressure.    
     
     
         10 . The process of  claim 9 , wherein said non-woven fabric sheet is composed of 95 to 70% by weight of said para-aramid fibers and 5 to 30 mass % of said thermosetting resin binder based on the total mass of said para-aramid fibers and said thermosetting resin binder.  
     
     
         11 . The process of  claim 9 , wherein said non-woven fabric sheet further contains 3 to 300 mass %, based on the total mass of said para-aramid fibers and said thermosetting resin binder, of thermoplastic resin fibers having a softening point of 220° C. or higher and/or thermosetting resin fibers having a glass transition temperature of 120° C. or higher.  
     
     
         12 . The process of  claim 9 , wherein said non-woven fabric sheet is in a wet state where it is not dried.  
     
     
         13 . The process of  claim 9 , wherein said non-woven fabric sheet is dried.  
     
     
         14 . The process of  claim 13 , wherein said non-woven fabric sheet is dried by heating it at 105 to 220° C.  
     
     
         15 . The process of  claim 14 , wherein a plurality of said non-woven fabric sheets are heated under pressure at a temperature of 30° or higher than said drying temperature and up to 400° C.  
     
     
         16 . The process of  claim 15 , wherein a plurality of said non-woven fabric sheets are heated at 200° C. or higher.  
     
     
         17 . The process of  claim 16 , wherein said heating is carried out by a pair of heated rolls.  
     
     
         18 . A prepreg obtained by impregnating the base material of  claim 1  with a thermosetting resin and then drying the same.  
     
     
         19 . A laminate obtained by molding the prepreg of  claim 18  by heating it under pressure.  
     
     
         20 . A laminate of  claim 19 , wherein at least one surface of said prepreg is laminated with a copper foil.