Optical recording medium

Abstract

An optical recording medium can be recorded at a high linear velocity of at least 10 m/s while maintaining an excellent light stability and favorable reflectance. A recording medium is constructed of a recording layer on a substrate, the recording layer including a first dye with a maximum absorption wavelength in a thin-film state of 450 nm to 620 nm inclusive as a first dye and being formed so as to include a second dye with an extinction coefficient of at least 0.5 for a recording wavelength. In this case, it is preferable for the second dye to have a maximum absorption wavelength of 620 nm to 750 nm inclusive in a thin-film state.

What is claimed is:  
     
         1 . An optical recording medium constructed by providing, on a substrate, a recording layer including a first dye, which in a thin-film state has a maximum absorption wavelength of 450 nm to 620 nm inclusive, as a main component, 
 the recording layer of the optical recording medium being formed so as to include a second dye with an extinction coefficient of at least 0.5 for a recording wavelength.    
     
     
         2 . An optical recording medium according to  claim 1 , 
 wherein in a thin-film state, the second dye has a maximum absorption wavelength of 620 nm to 750 nm inclusive.    
     
     
         3 . An optical recording medium according to  claim 1 , 
 wherein the extinction coefficient of the recording layer in a thin-film state is in a range of 0.03 to 0.1 inclusive for a wavelength of 660 nm.    
     
     
         4 . An optical recording medium according to  claim 2 , 
 wherein the extinction coefficient of the recording layer in a thin-film state is in a range of 0.03 to 0.1 inclusive for a wavelength of 660 nm.    
     
     
         5 . An optical recording medium according to  claim 1 , 
 wherein the recording layer is formed so as to include 0.5% to 5% inclusive by weight of the second dye.    
     
     
         6 . An optical recording medium according to  claim 2 , 
 wherein the recording layer is formed so as to include 0.5% to 5% inclusive by weight of the second dye.    
     
     
         7 . An optical recording medium according to  claim 3 , 
 wherein the recording layer is formed so as to include 0.5% to 5% inclusive by weight of the second dye.    
     
     
         8 . An optical recording medium according to  claim 1 , 
 wherein the first dye is one or a combination of two or more metal azo dyes selected from a group consisting of chelate compounds of a metal and a dye shown by a general formula (I) below                          where A represents residue that forms, together with the carbon atom and nitrogen atom with which A is combined, a heterocyclic ring, B represents residue that forms, together with two carbon atoms with which B is combined, an aromatic ring or a heterocyclic ring, and X represents a hydroxyl group, a carboxyl group, a sulfonic acid-derivative group, or (NSO 2 Q) − , where Q represents an alkyl group of one to six carbon atoms that an alkyl group of one to six carbon atoms that may be substituted with one or more fluorine atoms as the substituent(s).    
     
     
         9 . An optical recording medium according to  claim 2 , 
 wherein the first dye is one or a combination of two or more metal azo dyes selected from a group consisting of chelate compounds of a metal and a dye shown by a general formula (I) below                          where A represents residue that forms, together with the carbon atom and nitrogen atom with which A is combined, a heterocyclic ring, B represents residue that forms, together with two carbon atoms with which B is combined, an aromatic ring or a heterocyclic ring, and X represents a hydroxyl group, a carboxyl group, a sulfonic acid-derivative group, or (NSO 2 Q) − , where Q represents an alkyl group of one to six carbon atoms that an alkyl group of one to six carbon atoms that may be substituted with one or more fluorine atoms as the substituent(s).    
     
     
         10 . An optical recording medium according to  claim 3 , 
 wherein the first dye is one or a combination of two or more metal azo dyes selected from a group consisting of chelate compounds of a metal and a dye shown by a general formula (I) below                          where A represents residue that forms, together with the carbon atom and nitrogen atom with which A is combined, a heterocyclic ring, B represents residue that forms, together with two carbon atoms with which B is combined, an aromatic ring or a heterocyclic ring, and X represents a hydroxyl group, a carboxyl group, a sulfonic acid-derivative group, or (NSO 2 Q) − , where Q represents an alkyl group of one to six carbon atoms that an alkyl group of one to six carbon atoms that may be substituted with one or more fluorine atoms as the substituent (s).    
     
     
         11 . An optical recording medium according to  claim 5 , 
 wherein the first dye is one or a combination of two or more metal azo dyes selected from a group consisting of chelate compounds of a metal and a dye shown by a general formula (I) below                          where A represents residue that forms, together with the carbon atom and nitrogen atom with which A is combined, a heterocyclic ring, B represents residue that forms, together with two carbon atoms with which B is combined, an aromatic ring or a heterocyclic ring, and X represents a hydroxyl group, a carboxyl group, a sulfonic acid-derivative group, or (NSO 2 Q) − , where Q represents an alkyl group of one to six carbon atoms that an alkyl group of one to six carbon atoms that may be substituted with one or more fluorine atoms as the substituent(s).    
     
     
         12 . An optical recording medium according to  claim 1 , 
 wherein the second dye is composed of a pentamethine cyanine dye shown by a general formula (II) below                          where R 1  and R 2  each separately represent an alkyl group of one to six carbon atoms that may be substituted or unsubstituted or an alkenyl group of one to six carbon atoms that may be substituted or unsubstituted, Z 1  and Z 2  each separately represent a heterocycle with five or six members or an atom group that forms a condensed ring including a heterocycle with five or six members, and Y expresses a univalent anion.    
     
     
         13 . An optical recording medium according to  claim 2 , 
 wherein the second dye is composed of a pentamethine cyanine dye shown by a general formula (II) below                          where R 1  and R 2  each separately represent an alkyl group of one to six carbon atoms that may be substituted or unsubstituted or an alkenyl group of one to six carbon atoms that may be substituted or unsubstituted, Z 1  and Z 2  each separately represent a heterocycle with five or six members or an atom group that forms a condensed ring including a heterocycle with five or six members, and Y expresses a univalent anion.    
     
     
         14 . An optical recording medium according to  claim 3 , 
 wherein the second dye is composed of a pentamethine cyanine dye shown by a general formula (II) below                          where R 1  and R 2  each separately represent an alkyl group of one to six carbon atoms that may be substituted or unsubstituted or an alkenyl group of one to six carbon atoms that may be substituted or unsubstituted, Z 1  and Z 2  each separately represent a heterocycle with five or six members or an atom group that forms a condensed ring including a heterocycle with five or six members, and Y expresses a univalent anion.    
     
     
         15 . An optical recording medium according to  claim 5 , 
 wherein the second dye is composed of a pentamethine cyanine dye shown by a general formula (II) below                          where R 1  and R 2  each separately represent an alkyl group of one to six carbon atoms that may be substituted or unsubstituted or an alkenyl group of one to six carbon atoms that may be substituted or unsubstituted, Z 1  and Z 2  each separately represent a heterocycle with five or six members or an atom group that forms a condensed ring including a heterocycle with five or six members, and Y expresses a univalent anion.    
     
     
         16 . An optical recording medium according to  claim 8 , 
 wherein the second dye is composed of a pentamethine cyanine dye shown by a general formula (II) below                          where R 1  and R 2  each separately represent an alkyl group of one to six carbon atoms that may be substituted or unsubstituted or an alkenyl group of one to six carbon atoms that may be substituted or unsubstituted, Z 1  and Z 2  each separately represent a heterocycle with five or six members or an atom group that forms a condensed ring including a heterocycle with five or six members, and Y expresses a univalent anion.