| 摘要 |
PURPOSE:To manufacture accurately, easily and at a low cost a PTFE extrusion molded product which has a smooth outside form and desired dimensions, by a method wherein an unfired polytetrafluoroethylene resin paste extrusion molded material is fired and cooled under a state where the same is inserted into a firing mold whose inside diameter is a little larger than outer diameterical dimensions of the same and sliding layer on an inner circumferential surface has low frictional resistance. CONSTITUTION:An extrusion auxiliary agent such as solvent naphtha or illuminating kerosine is compounded with unfired PTFE resin powder to give fluidity to the same at a temperature close to a room temperature, which is premolded into a cylindrical or columnar state and a premolded material is formed. An unfired PTFE resin paste extrusion molded material 2 extruded through a die 1 of an extrusion machine is inserted into a firing mold 6 having the inside diameter D a little larger than the outside diameter d1 of the molded material 2. The firing mold 6 into which the paste extrusion molded material 2 is inserted is moved into a furnace 8, a temperature within the furnace 8 is raised and the paste extrusion molded material 2 in the firing mold 6 is fired. |
