Method and apparatus for orienting an optical polymer film, and tenter apparatus for the same

Abstract

A polymer-film orienting machine comprises a processing apparatus and a tenter apparatus. The processing apparatus comprises a cleaning bath, a dyeing bath and a hardening bath. The cleaning bath is provided with a draining roller pair and a draining blade pair. The draining roller pair is constituted of two draining rollers. The draining blade pair is constituted of two draining blades. The draining roller pair is disposed at a position where the PVA film has just passed through the cleaning bath. The draining blade pair is disposed at a downstream side of the draining roller pair in a conveyance direction of the PVA film. Similarly to the cleaning bath, the dyeing bath and the hardening bath are respectively provided with a draining roller pair and a draining blade pair.

What is claimed is:  
     
         1 . An orienting method for an optical polymer film, said polymer film being oriented after passing through at least one processing bath containing a fluid, said orienting method comprising a step of: 
 removing the fluid, which exists on said polymer film, by using a draining member within 10 seconds from the moment that said polymer film has left said processing bath.    
     
     
         2 . An orienting method for an optical polymer film according to  claim 1 , wherein said draining member is disposed at an exit of at least the first processing bath when there are the plural processing baths.  
     
     
         3 . An orienting method for an optical polymer film according to  claim 1 , wherein said draining member is disposed at an exit of at least the last processing bath when there are the plural processing baths.  
     
     
         4 . An orienting method for an optical polymer film according to  claim 1 , wherein said processing baths include a cleaning bath for cleaning said polymer film, a dyeing bath for dyeing said polymer film, and a hardening bath for hardening said polymer film.  
     
     
         5 . An orienting method for an optical polymer film according to  claim 4 , wherein said polymer film is oriented in a pneumatic atmosphere after passing through said cleaning bath, said dyeing bath, and said hardening bath in order.  
     
     
         6 . An orienting method for an optical polymer film according to  claim 1 , wherein said polymer film is a polyvinyl alcohol film.  
     
     
         7 . An orienting method for an optical polymer film, comprising the steps of: 
 cleaning the strip-form polymer film with a cleaning fluid contained in a cleaning bath through which said polymer film continuously passes;    removing said cleaning fluid existing on both surfaces of said polymer film, with first draining blades disposed near a film exit of said cleaning bath;    dyeing said polymer film with a dyeing fluid contained in a dyeing bath through which said polymer film continuously passes;    removing said dyeing fluid existing on both surfaces of said polymer film, with second draining blades disposed near a film exit of said dyeing bath;    hardening said polymer film with a hardening fluid contained in a hardening bath through which said polymer film continuously passes;    removing said hardening fluid existing on both surfaces of said polymer film, with third draining blades disposed near a film exit of said hardening bath; and    orienting said hardened polymer film in the air.    
     
     
         8 . An orienting apparatus for an optical polymer film, said polymer film being oriented in a pneumatic atmosphere after passing through at least one processing bath containing a fluid, said orienting apparatus comprising: 
 a draining member for removing the fluid existing on said optical polymer film, said draining member being disposed near a film exit of said processing bath.    
     
     
         9 . An orienting apparatus for an optical polymer film according to  claim 8 , wherein said draining member includes one of a draining roller and a draining blade.  
     
     
         10 . An orienting apparatus for an optical polymer film according to  claim 9 , wherein said processing baths include a cleaning bath for cleaning said polymer film, a dyeing bath for dyeing said polymer film, and a hardening bath for hardening said polymer film.  
     
     
         11 . An orienting apparatus for an optical polymer film according to  claim 10 , wherein said polymer film is a polyvinyl alcohol film.  
     
     
         12 . An orienting apparatus for an optical polymer film, comprising: 
 a cleaning bath for cleaning the strip-form polymer film with a cleaning fluid;    a first draining blades disposed near a film exit of said cleaning bath, said first draining blades removing said cleaning fluid existing on both surfaces of said polymer film;    a first rubber-roller pair disposed between the film exit of said cleaning bath and the first draining blades, said first rubber-roller pair nipping said polymer film and preventing said cleaning fluid from dripping therefrom;    a dyeing bath for dyeing said polymer film with a dyeing fluid;    a second draining blades disposed near a film exit of said dyeing bath, said second draining blades removing said dyeing fluid existing on both surfaces of said polymer film;    a second rubber-roller pair disposed between the film exit of said dyeing bath and the second draining blades, said second rubber-roller pair nipping said polymer film and preventing said dyeing fluid from dripping therefrom;    a hardening bath for hardening said polymer film with a hardening fluid;    a third draining blades disposed near a film exit of said hardening bath, said third draining blades removing said hardening fluid existing on both surfaces of said polymer film;    a third rubber-roller pair disposed between the film exit of said hardening bath and the third draining blades, said third rubber-roller pair nipping said polymer film and preventing said hardening fluid from dripping therefrom; and    a tenter apparatus for orienting said hardened polymer film in the air.    
     
     
         13 . An orienting apparatus according to  claim 12 , wherein said first through third draining blades respectively include a front blade for contacting with the front of said polymer film, and a back blade for contacting with the back of said polymer film, said front blade and said back blade being disposed at different positions in a conveyance direction of said polymer film.  
     
     
         14 . An orienting apparatus according to  claim 13 , wherein said front blade and said back blade have a toe formed in an arc shape whose radius is 0.1 to 1 mm, and surface roughness of the toe is 5 S or less.  
     
     
         15 . An orienting apparatus according to  claim 14 , wherein said first through third rubber-roller pairs have hardness of 50 degrees to 90 degrees and surface roughness of 0.5 S to 10 S, and linear pressure of nip thereof is 100 N/m to 500 N/m.  
     
     
         16 . A tenter apparatus in which a strip-form polymer film, both side edges of which are held by openable clampers, is conveyed along a first rail and a second rail to stretch a width thereof, said tenter apparatus comprising: 
 gripping-force aid means for applying a force in a closed direction of said clamper, said gripping-force aid means being disposed within a range running from a grip commencement position of the clamper to a grip release position of the clamper.    
     
     
         17 . A tenter apparatus according to  claim 16 , wherein orienting areas for performing plural sorts of orientation are formed between said first rail and said second rail, said gripping-force aid means being disposed within at least one of said orienting areas.  
     
     
         18 . A tenter apparatus according to  claim 16 , wherein said first rail and said second rail include a linear portion and a curving portion bending in an arc shape, said gripping-force aid means being disposed in front and in rear of said curving portion.  
     
     
         19 . A tenter apparatus according to  claim 16 , wherein said gripping-force aid means is disposed at a position prior to thermal processing.  
     
     
         20 . A tenter apparatus for stretching a width of a strip-form polymer film, comprising: 
 a plurality of clips movable in a closed direction and an open direction, said clip gripping a lateral end of said polymer film when moving in the closed direction, and said clip releasing the lateral end of said polymer film from a grip when moving in the open direction;    first and second endless moving means oppositely disposed, the respective endless moving means holding said clips at predetermined intervals and moving at a constant speed;    first and second rails disposed in association with said first and second endless moving means so as to form a conveyance passage of said polymer film, said first and second rails defining a movement locus of the respective clips when the respective clips are moved by said first and second endless means in a conveyance direction of said polymer film, gripping the lateral end of said polymer film; and    gripping-force aid means disposed somewhere along said movement locus defined by said first and second rails, said gripping-force aid means pressing the respective clips in the closed direction to increase a force for gripping said lateral end.    
     
     
         21 . A tenter apparatus according to  claim 20 , wherein said conveyance passage of the polymer film has an entrance portion, a midway portion for orienting said polymer film, and an exit portion; 
 said first rail and said second rail are parallel at the entrance portion and the exit portion;    a width of said exit portion is wider than a width of said entrance portion, and said exit portion inclines relative to said entrance portion;    an inclination of said first rail relative to said entrance portion is larger than that of said second rail at a former half of said midway portion; and    said first rail connects in a first arc of a larger arc-angle and said second rail connects in a second arc of a smaller arc-angle, at a latter half of said midway portion and said exit portion.    
     
     
         22 . A tenter apparatus according to  claim 21 , wherein said clip comprises: 
 a U-shaped frame having a holding surface on which a side edge of said polymer film is placed; and    a flapper rotatably attached to said frame, said polymer film being held by a bottom surface of said flapper and said holding surface of said frame.    
     
     
         23 . A tenter apparatus according to  claim 22 , wherein said gripping-force aid means comprises: 
 a close cam for coming into contact with an upper end of said flapper to press said flapper in the closed direction;    a shaft having a first-end side to which said close cam is attached;    a bearing for supporting said shaft in a slidable manner;    a stopper attached to a second-end side of said shaft; and    a spring disposed between said bearing and said stopper, said spring adjusting a force of said close cam for pressing the upper end of said flapper.    
     
     
         24 . A tenter apparatus according to  claim 23 , wherein said gripping-force aid means is disposed in said midway portion and said close cams are arranged along said first and second rails.  
     
     
         25 . A tenter apparatus according to  claim 24 , wherein said close cams are disposed at positions corresponding to said first and second arcs.  
     
     
         26 . A tenter apparatus according to  claim 25 , wherein said polymer film is heated at the entrance portion and the midway portion in order to easily perform orientation.