Optical recording medium and method of producing the same

Abstract

An optical recording medium capable of suppressing film thickness irregularity of interlayer between a plurality of optical recording layers and effects of warps of a transfer substrate and arising of dusts and burrs problems, etc. and a method of producing the optical recording medium are provided. An optical recording medium has a structure wherein at least two optical recording layers ( 11, 13 ) stacked via an interlayer 12 and a light transmitting layer 14 provided on the optical recording layer are provided at least one surface of a medium substrate 10, for performing recording and reproducing by irradiating a light to the optical recording layers ( 11, 13 ) through the light transmitting layer 14, and the interlayer includes at least one layer of ultraviolet curing resin film made to be a film in advance and is a film formed with an uneven shape corresponding to a recording pit or an uneven shape ( 12 p ) to be a guide groove on its surface and cured.

1 .- 4 . (canceled)  
   
   
       5 . A method of producing an optical recording medium having at least two optical recording layers, including a step of forming a medium substrate having an uneven shape on its one surface, a step of forming a first optical recording layer on the uneven shape formation surface of said medium substrate, a step of forming an interlayer having an uneven shape on its surface on said first optical recording layer, a step of forming a second optical recording layer on the uneven shape formation surface of said interlayer, and a step of forming a light transmitting protective layer on said second optical recording layer; wherein 
 the step of forming said interlayer includes 
 a step of adhering one surface of an ultraviolet curing resin film made to be a film in advance to said first optical recording layer or a transfer substrate formed with an uneven shape,  
 a step of pressing said transfer substrate or said first optical recording layer directly or via other layer against said resin film and providing an uncured interlayer including at least one layer of said resin film between said first optical recording layer and said transfer substrate,  
 a step of curing said interlayer in a state of pressing said transfer substrate against the surface of said interlayer, and  
 a step of releasing said transfer substrate from said interlayer and transferring the uneven shape of said transfer substrate to the surface of said interlayer.  
   
   
   
       6 . A method of producing an optical recording medium as set forth in  claim 5 , wherein: 
 said resin film is an ultraviolet curing resin film made to be a film in a state of being sandwiched by a pair of release films; and    the step of forming said interlayer further includes a step of releasing one of said release films from said resin film before the step of adhering said resin film to said first optical recording layer or said transfer substrate, and a step of releasing the other of said release films from said resin film after the step of adhering said resin film to said first optical recording layer or said transfer substrate and before the step of pressing said transfer substrate or said first optical recording layer directly or via other layer against said resin film.    
   
   
       7 . A method of producing an optical recording medium as set forth in  claim 5 , wherein said interlayer is formed only with said resin film in the step of forming said interlayer.  
   
   
       8 . A method of producing an optical recording medium as set forth in  claim 5 , wherein the step of forming said interlayer includes a step of adhering said resin film on said transfer substrate, a step of forming a coating film of an ultraviolet curing liquid resin composition on said first optical recording layer, a step of adhering said resin film and said coating film, a step of obtaining said interlayer by curing said resin film and said coating film in a state of being adhered to each other, and a step of releasing said transfer substrate from said interlayer.  
   
   
       9 . A method of producing an optical recording medium as set forth in  claim 5 , wherein the step of forming said interlayer includes a step of forming a coating film of an ultraviolet curing liquid resin composition on said transfer substrate, a step of adhering said resin film on said first optical recording layer, a step of adhering said resin film and said coating film, a step of obtaining said interlayer by curing said resin film and said coating film in a state of being adhered to each other, and a step of releasing said transfer substrate from said interlayer.  
   
   
       10 . A method of producing an optical recording medium as set forth in  claim 5 , wherein one made by an injection molded plastic material having a larger outer circumference diameter than that of said medium substrate is used as said transfer substrate.  
   
   
       11 . A method of producing an optical recording medium as set forth in  claim 5 , wherein one made by a plastic material having a thickness of 0.5 mm or less is used as said transfer substrate.  
   
   
       12 . A method of producing an optical recording medium as set forth in  claim 5 , wherein one made by a plastic material wherein the outer circumference diameter is taper shaped and thinner than the center portion is used as said transfer substrate.  
   
   
       13 . A method of producing an optical recording medium as set forth in  claim 5 , wherein adhesion with pressure is performed from the transfer substrate side by an elastic body in the step of transferring by using said transfer substrate.