Gasket and method of manufacturing the gasket

Abstract

A gasket is capable of providing an excellent slidability and holding its sealability without applying lubricant and a gasket that can prevent a resin film from being peeled off of a gasket body and prevent the generation of a molding defect such as pinholes. The gasket can be installed slidably in a outer tube of a syringe, including a gasket body and a resin film formed of a material lower in coefficient of friction than a material of the gasket body, which covers at least an outer periphery of the gasket body, in which when a surface roughness of the resin film on the outer tube side is defined as Ra 1 and a surface roughness of the resin film on the gasket body side is defined as Ra 2 , a relationship of 1.5 Ra 1 ≦Ra 2 is satisfied.

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         11 . A method of manufacturing a gasket by covering an outer periphery of a gasket body with a resin film manufactured by a skiving processing to obtain a gasket including: placing the resin film and a gasket body material formed of a material capable of obtaining an elasticity by vulcanization in a molding die; performing heating and pressurizing to vulcanize the material capable of obtaining the elasticity by the vulcanization; and coating the resin film on an outer peripheral surface of the gasket body to obtain the gasket.  
     
     
         12 . The method of manufacturing a gasket according to  claim 11 , in which the heating is performed at a temperature of 140 to 180° C.  
     
     
         13 . The method of manufacturing a gasket according to  claim 11 , in which the pressurizing is performed at a pressure of 0.5 to 25 MPa.  
     
     
         14 . The method of manufacturing a gasket according to  claim 11 , in which a surface roughening is performed on a surface of the resin film on the gasket body side prior to molding.  
     
     
         15 . The method of manufacturing a gasket according to  claim 14 , in which the surface roughening is one performed by an etching process.  
     
     
         16 . The method of manufacturing a gasket according to  claim 14 , in which the surface of the resin film on the gasket body side satisfies a relation of a coefficient of kinetic friction ratio F=D 2 /D 1 ≧2 when a coefficient of kinetic friction (against a sapphire needle) before the surface roughening is defined as D 1  and a coefficient of kinetic friction (against a sapphire needle) after the surface roughening is defined as D 2 .  
     
     
         17 . The method of manufacturing a gasket according to  claim 11 , in which the surface of the resin film on the gasket body side satisfies the relation in which Ra 4 /Ra 3  is 0.25 to 0.9 when a surface roughness before molding is defined as Ra 3  and a surface roughness after molding is defined as Ra 4 .  
     
     
         18 . The method of manufacturing a gasket according to  claim 17 , in which the surface roughness Ra 4  is 0.1 to 1.5 μm.  
     
     
         19 . The method of manufacturing a gasket according to  claim 11 , in which a surface of the resin film opposite to the gasket body side has a coefficient of kinetic friction (against a sapphire needle) after molding of 0.3 or less.  
     
     
         20 . The method of manufacturing a gasket according to  claim 11 , in which an average thickness T 1  of the resin film before molding is 25 μm or more.  
     
     
         21 . The method of manufacturing a gasket according to  claim 11 , in which an average thickness T 2  of the resin film after molding is 1 to 200 μm.  
     
     
         22 . The method of manufacturing a gasket according to  claim 11 , in which the resign film is covered with the gasket body such that the gasket material enters into a plurality of minute recessed portions of the surface of the resin film on the gasket body side.  
     
     
         23 . The method of manufacturing a gasket according to  claim 11 , in which the resin film is formed of a material lower in coefficient of friction than the gasket body material.  
     
     
         24 . The method of manufacturing a gasket according to  claim 12 , in which the pressurizing is performed at a pressure of 0.5 to 25 MPa.  
     
     
         25 . The method of manufacturing a gasket according to  claim 12 , in which a surface roughening is performed on a surface of the resin film on the gasket body side prior to molding.  
     
     
         26 . The method of manufacturing a gasket according to  claim 13 , in which a surface roughening is performed on a surface of the resin film on the gasket body side prior to molding.  
     
     
         27 . The method of manufacturing a gasket according to  claim 12 , in which the surface of the resin film on the gasket body side satisfies the relation in which Ra 4 /Ra 3  is 0.25 to 0.9 when a surface roughness before molding is defined as Ra 3  and a surface roughness after molding is defined as Ra 4 .  
     
     
         28 . The method of manufacturing a gasket according to  claim 13 , in which the surface of the resin film on the gasket body side satisfies the relation in which Ra 4 /Ra 3  is 0.25 to 0.9 when a surface roughness before molding is defined as Ra 3  and a surface roughness after molding is defined as Ra 4 .  
     
     
         29 . The method of manufacturing a gasket according to  claim 12 , in which a surface of the resin film opposite to the gasket body side has a coefficient of kinetic friction (against a sapphire needle) after molding of 0.3 or less.  
     
     
         30 . The method of manufacturing a gasket according to  claim 13 , in which an average thickness T 1  of the resin film before molding is 25 μm or more.