Microporous stencil sheet and application thereof

Abstract

A microporous stencil sheet for use in stencil printing and methods for making stencil master using this microporous stencil sheet are disclosed herein. The microporous stencil sheet is for use in stencil printing using a low-viscosity ink with a viscosity ranging from 0.001 to 1 Pa•s, comprises an inelastic resin film and has an air permeability ranging from 1 to 600 seconds and a thickness ranging from 1 to 100 μm. The methods for making stencil master using this microporous stencil sheet comprise the step of closing the micropores of the stencil sheet in a non-printing portion of a desired printed image.

What is claimed is:  
     
         1 . A microporous stencil sheet composed of an inelastic resin film for use in stencil printing, wherein the microporous stencil sheet has an air permeability ranging from 1 to 600 seconds and a thickness ranging from 1 to 100 μm and is for use in stencil printing using a low-viscosity ink with a viscosity ranging from 0.001 to 1 Pa•s.  
     
     
         2 . A microporous stencil sheet according to  claim 1 , wherein the inelastic resin film is a thermoplastic resin film.  
     
     
         3 . A microporous stencil sheet according to  claim 2 , wherein the inelastic resin film is a polyolefin film.  
     
     
         4 . A microporous stencil sheet according to  claim 1 , wherein the micropores of the microporous stencil sheet have a mean pore size ranging from 0.01 to 10 μm.  
     
     
         5 . A microporous stencil sheet according to  claim 1 , wherein the microporous stencil sheet has micropores formed by stretching out the inelastic resin film in at least one axial direction.  
     
     
         6 . A microporous stencil sheet according to  claim 1 , wherein the microporous stencil sheet has a photo-thermal conversion substance on the surface or inside of the microporous stencil sheet.  
     
     
         7 . A microporous stencil sheet according to  claim 1 , wherein the microporous stencil sheet has an antistatic agent on the surface or inside of the microporous stencil sheet.  
     
     
         8 . A microporous stencil sheet according to  claim 1 , wherein the microporous stencil sheet has a releasing layer on its surface, the releasing layer comprising a release agent selected from the group consisting of silicone-based release agents, fluorine-based release agents, wax-based release agents, and surfactant-based release agents.  
     
     
         9 . A microporous stencil sheet according to  claim 8 , wherein the releasing layer comprises a release agent containing a silicone phosphate ester as a principal component.  
     
     
         10 . A method for making a stencil master using a microporous stencil sheet, the microporous stencil sheet comprising a thermoplastic resin film and having an air permeability ranging from 1 to 600 seconds and a thickness ranging from 1 to 100 μm, the method comprising the step of closing, by heat fusion, the micropores of the microporous stencil sheet in a non-printing portion of a desired printed image to form an ink-impermeable portion.  
     
     
         11 . A method according to  claim 10 , wherein the heat fusion is performed by heat generated from a thermal head.  
     
     
         12 . A method according to  claim 10 , wherein the microporous stencil sheet has a photo-thermal conversion substance on the surface or inside of the microporous stencil sheet, and wherein the heat fusion is performed by irradiation with electromagnetic waves.  
     
     
         13 . A method for making a stencil master using a microporous stencil sheet, the microporous stencil sheet having an air permeability ranging from 1 to 600 seconds and a thickness ranging from 1 to 100 μm, the method comprising the step of closing the micropores of the microporous stencil sheet in a non-printing portion of a desired printed image by deposition of a resin, wax or both to form an ink-impermeable portion.  
     
     
         14 . A method according to  claim 13 , wherein the resin, wax or both are deposited from a thermal transfer sheet by fusion transfer.  
     
     
         15 . A stencil master obtained by the method for making a stencil master according to  claim 10 .  
     
     
         16 . A stencil master obtained by the method for making a stencil master according to claim  13 .