Compressible printing blanket and method of manufacturing a compressible printing blanket

Abstract

Disclosed is a compressible printing blanket in which voids are formed in the compressible layer by using microballoons, comprising at least two fabric layers, an adhesive layer interposed between adjacent fabric layers, a surface rubber layer, and a compressible layer arranged between the at least two fabric layers and the surface rubber layer and containing spherical voids and voids having a shape other than a sphere in a ratio defined in formula given below: S 1 :S 2 20:80 to 95:5   ( 1 ) where, S 1 denotes the number of spherical voids per unit area in a cross section of the compressible layer, and S 2 denotes the number of voids having a shape other than a sphere per unit area in a cross section of the compressible layer.

What is claimed is:  
     
         1 . A compressible printing blanket in which voids are formed in the compressible layer by using microballoons, comprising: 
 at least two fabric layers;    an adhesive layer interposed between adjacent fabric layer;    a surface rubber layer; and    a compressible layer arranged between said at least two fabric layers and said surface rubber layer and containing spherical voids and voids having a shape other than a sphere in a ratio defined in formula given below:    S 1 :S 2 20:80 to 95:5   (1)    where, S 1  denotes the number of spherical voids per unit area in a cross section of said compressible layer, and S 2  denotes the number of voids having a shape other than a sphere per unit area in a cross section of said compressible layer.    
     
     
         2 . The compressible printing blanket according to  claim 1 , wherein said compressible layer contains glycols.  
     
     
         3 . The compressible printing blanket according to  claim 2 , wherein the content of said glycols in said compressible layer falls within a range of between 0.1 and 15 parts by weight.  
     
     
         4 . The compressible printing blanket according to  claim 1 , wherein the thickness of said compressible layer falls within a range of between 0.2 mm and 0.6 mm.  
     
     
         5 . The compressible printing blanket according to  claim 1 , wherein the thickness of said adhesive layer falls within a range of between 0.03 mm and 0.6 mm.  
     
     
         6 . The compressible printing blanket according to  claim 1 , wherein said adhesive layer contains voids.  
     
     
         7 . The compressible printing blanket according to  claim 1 , wherein said adhesive layer contains microballoons.  
     
     
         8 . The compressible printing blanket according to  claim 1 , wherein said adhesive layer contains spherical voids and voids having a shape other than a sphere formed by using microballoons.  
     
     
         9 . The compressible printing blanket according to  claim 8 , wherein the ratio between the spherical voids and the voids having a shape other than a sphere meets formula (3) given below:  
       P 1 :P 2 20:80 to 95:5   (3)  where P 1  denotes the number of spherical voids per unit area in a cross section of the adhesive layer, and P 2  denotes the number of voids having a shape other than a sphere per unit area in a cross section of the adhesive layer.    
     
     
         10 . The compressible printing blanket according to  claim 8 , wherein said adhesive layer contains glycols.  
     
     
         11 . A method of manufacturing a compressible printing blanket, comprising vulcanizing a blanket precursor at temperatures not lower than 120° C., said blanket precursor including at least two fabric layers, an unvulcanized adhesive layer interposed between adjacent fabric layers, an unvulcanized surface rubber layer, and an unvulcanized compressible layer arranged between said at least two fabric layers and said unvulcanized surface rubber layer, and said unvulcanized compressible layer containing microballoons and a melting agent of said microballoons.  
     
     
         12 . The method of manufacturing a compressible printing blanket according to  claim 11 , wherein said melting agent contains glycols.  
     
     
         13 . The method of manufacturing a compressible printing blanket according to  claim 11 , wherein the content of said melting agent in said unvulcanized compressible layer falls within a range of between 0.1 and 15 parts by weight.  
     
     
         14 . The method of manufacturing a compressible printing blanket according to  claim 11 , wherein the content of said melting agent in said unvulcanized compressible layer falls within a range of between 0.1 and 15 parts by weight, and the content of said microballoons in said unvulcanized compressible layer falls within a range of between 5 and 15 parts by weight.  
     
     
         15 . The method of manufacturing a compressible printing blanket according to  claim 11 , wherein said microballoons contains a copolymer between methacrylonitrile and acrylonitrile.  
     
     
         16 . The method of manufacturing a compressible printing blanket according to  claim 11 , wherein the average particle diameter of said microballoons falls within a range of between 1 μm and 200 μm.  
     
     
         17 . The method of manufacturing a compressible printing blanket according to  claim 11 , wherein said unvulcanized adhesive layer contains microballoons.  
     
     
         18 . The method of manufacturing a compressible printing blanket according to  claim 11 , wherein said unvulcanized adhesive layer contains microballoons and a melting agent of said microballoons.  
     
     
         19 . A method of manufacturing a compressible printing blanket, comprising: 
 applying a vulcanizing treatment at temperatures not lower than 120° C. to a laminate structure including a fabric layer, a reinforcing layer, and an unvulcanized compressible layer arranged between said fabric layer and said reinforcing layer, and said unvulcanized compressible layer containing microballoons and a melting agent of said microballoons;    laminating at least one new fabric layer on said fabric layer of said laminate structure with an unvulcanized adhesive layer interposed between these fabric layers and laminating an unvulcanized surface rubber layer on said reinforcing layer of said laminate structure with an unvulcanized adhesive rubber layer interposed therebetween so as to obtain a rubber blanket precursor; and    vulcanizing said rubber blanket precursor at temperatures not lower than 120° C.    
     
     
         20 . The method of manufacturing a compressible printing blanket according to  claim 19 , wherein said melting agent contains glycols.  
     
     
         21 . The method of manufacturing a compressible printing blanket according to  claim 19 , wherein the content of said melting agent in said unvulcanized compressible layer falls within a range of between 0.1 and 15 parts by weight.  
     
     
         22 . The method of manufacturing a compressible printing blanket according to  claim 19 , wherein the content of said melting agent in said unvulcanized compressible layer falls within a range of between 0.1 and 15 parts by weight, and the content of said microballoons in said unvulcanized compressible layer falls within a range of between 5 and 15 parts by weight.  
     
     
         23 . The method of manufacturing a compressible printing blanket according to  claim 19 , wherein said microballoon contains a copolymer between methacrylonitrile and acrylonitrile.  
     
     
         24 . The method of manufacturing a compressible printing blanket according to  claim 19 , wherein the average particle diameter of said microballoons falls within a range of between 1 μm and 200 μm.  
     
     
         25 . The method or manufacturing a compressible printing blanket according to  claim 19 , wherein said unvulcanized adhesive layer contains microballoons.  
     
     
         26 . The method of manufacturing a compressible printing blanket according to  claim 19 , wherein said unvulcanized adhesive layer contains microballoons and a melting agent of said microballoons.  
     
     
         27 . The printing compressible blanket according to  claim 1 , wherein the compressible layer is not of an open cell structure.  
     
     
         28 . The printing compressible blanket according to  claim 1 , wherein the compressible layer has a partially open cell structure.  
     
     
         29 . The printing compressible blanket according to  claim 1 , wherein the voids having a shape other than a sphere are closed voids that are formed by melting of at least one microcapsules.