Compound, optical recording medium and optical recording method

Details Compound, optical recording medium and optical recording method Compound, optical recording medium and optical recording method

2002-12-06

2004-11-09

Mulvaney, Elizabeth (Department: 1774)

Stock material or miscellaneous articles

Circular sheet or circular blank

C428S064400, C428S064800, C430S270140, C430S270150

Reexamination Certificate

active

06815033

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a write-once optical recording medium which employs an organic dye for a recording layer. Particularly, it relates to a novel compound corresponding to blue laser, a write-once optical recording medium and an optical recording method.
2. Discussion of Background
At present, various optical recording media such as CD-R/RW, DVD-R/RW and MO have been widely recognized and used as an external memory for an information processor such as a computer, since they can record a large amount of information, and random access is easy with them. Among these optical recording media, organic dye type optical recording media typified by CD-R and DVD-R are considered to be superior to others from such a viewpoint that they can easily be produced at a low cost.
Further, along with increase in the amount of information to be recorded, it has been desired to increase the recording density of media. In recent years, an optical recording medium on which high density recording/readout can be carried out by using laser with a short oscillation wavelength, such as blue laser which has significantly been developed, has been proposed.
In general, with respect to optical recording media commercially available as CD-R or DVD-R, for example, CD-R is designed to be applicable to recording/readout by a laser beam having a wavelength at a level of 780 nm, and DVD-R is designed to be applicable to recording/readout by a laser beam having a wavelength at a level of from 600 to 700 nm. Such a recording medium applicable to optical recording/readout by using a laser beam having a relatively long wavelength has such problems that when recording/readout is carried out by using laser with a shorter wavelength, the refractivity tends to be low, and recording/readout cannot be carried out. It is an object of the present invention to provide an organic dye type optical recording medium on which recording/readout can be carried out by blue laser with a shorter wavelength.
SUMMARY OF THE INVENTION
The present inventors have conducted various studies on organic dyes having a high sensitivity to blue laser and as a result, they have found that compounds of the following formulae [I] and [II] can be used for a recording layer of an optical recording medium corresponding to blue laser, and the present invention has been accomplished on the basis of this discovery.
Namely, the present invention provides an optical recording medium comprising a substrate and a recording layer on which recording and readout of information can be carried out by laser, formed on the substrate, wherein the recording layer contains a compound of the following formula [I] or [II], and an optical recording method, which comprises recording information on the optical recording medium by using a laser beam having a wavelength of from 350 to 530 nm:
wherein each of R
1
to R
4
is a hydrogen atom or an optional substituent, provided that R
1
and R
2
, and R
3
and R
4
, may be bonded to form a hydrocarbon ring or a heterocyclic ring structure, and the hydrocarbon ring and the heterocyclic ring may have a substituent;
X
1
is an electro-withdrawing group, and X
2
is a hydrogen atom or —Q—Y (wherein Q is a direct bonding, a C
1-2
alkylene group, an arylene group or a heteroarylene group, and Y is an electro-withdrawing group, provided that the alkylene group, the arylene group and the heteroarylene group may have an optional substituent in addition to Y); and
Z is —O—, —S—, —SO
2
— or —NR
5
— [wherein R
5
is a hydrogen atom, a hydrocarbon group which may be substituted, a heterocyclic group which may be substituted, a cyano group, a hydroxyl group, an amino group represented by —NR
6
R
7
(wherein each of R
6
and R
7
which are independent of each other, is a hydrogen atom, a hydrocarbon group which may be substituted, a heterocyclic group which may be substituted or —COR
8
<wherein R
8
is a hydrocarbon group which may be substituted or a heterocyclic group which may be substituted>) or —COR
9
(wherein R
9
is a hydrocarbon group which may be substituted or a heterocyclic group which may be substituted), provided that when R
5
is a hydrocarbon group, it may be bonded with R
2
or R
4
to form a cyclic structure];
wherein each of R
1
to R
4
is a hydrogen atom or an optional substituent, provided that R
1
and R
2
, and R
3
and R
4
, may be bonded to form a hydrocarbon ring or a heterocyclic ring structure, and the hydrocarbon ring and the heterocyclic ring may have a substituent;
the ring A is a carbocyclic ketone ring or a heterocyclic ketone ring which may have a substituent, formed together with C═O; and
Z is —O—, —S—, —SO
2
— or —NR
5
— [wherein R
5
is a hydrogen atom, a hydrocarbon group which may be substituted, a heterocyclic group which may be substituted, a cyano group, a hydroxyl group, an amino group represented by —NR
6
R
7
(wherein each of R
6
and R
7
which are independent of each other, is a hydrogen atom, a hydrocarbon group which may be substituted, a heterocyclic group which may be substituted or —COR
8
<wherein R
8
is a hydrocarbon group which may be substituted or a heterocyclic group which may be substituted>) or —COR
9
(wherein R
9
is a hydrocarbon group which may be substituted or a heterocyclic group which may be substituted), provided that when R
5
is a hydrocarbon group, it may be bonded with R
2
or R
4
to form a cyclic structure].
The present invention further provides a novel compound of the following formula [I′]:
wherein each of R
1
to R
4
is a hydrogen atom or an optional substituent, provided that R
1
and R
2
, and R
3
and R
4
, may independently be bonded to form a hydrocarbon ring or a heterocyclic ring structure, and the hydrocarbon ring and the heterocyclic ring may have a substituent; each of X
1
and Y is an electro-withdrawing group, provided that one of X
1
and Y is a cyano group, and the other is —COOR
11
(wherein R
11
is a hydrogen atom, a hydrocarbon group which may be substituted or a heterocyclic group which may be substituted) or —SO
2
R
17
(wherein R
17
is a hydrocarbon group which may be substituted or a heterocyclic group which may be substituted); and
Z is —NR
5
— (wherein in a case where one of X
1
and Y is —COOR
11
, R
5
is a C
3-18
branched alkyl group which may be substituted, a C
3-18
cyclic alkyl group which may be substituted or a 5- or 6-membered saturated heterocyclic group which may be substituted, and in a case where one of X
1
and Y is —SO
2
R
17
, R
5
is a C
1-18
linear or branched alkyl group which may be substituted, a C
3-18
cyclic alkyl group which may be substituted or a 5- or 6-membered saturated heterocyclic group which may be substituted).


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