Incremental printing of symbolic information – Ink jet – Fluid or fluid source handling means
Reexamination Certificate
2000-03-31
2002-06-25
Barlow, John (Department: 2853)
Incremental printing of symbolic information
Ink jet
Fluid or fluid source handling means
C347S101000
Reexamination Certificate
active
06409328
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to an image-forming material suitable for the image formation using a thermal printer head and a method of forming images by the use of such a material. Specifically, the invention is concerned with a method of image formation based on the thermal reaction between a thermoacid generator and a material of forming a dye by the reaction with an acid (or a color former). More specifically, the invention relates to a material enabling the image formation utilizing an acid and/or dye multiplication system and having high sensitivity and good keeping quality, and further to a method for image formation using such a material.
BACKGROUND OF THE INVENTION
The thermal recording is a method of forming images with gradation depending on the magnitude of thermal energy applied. As to the mechanism employed therein for image formation, various ways have been devised, wherein the thermal energy applied causes fusion or sublimation transfer of colorants, a coloring reaction between two components via thermal fusion or capsule rupture, a change in optical characteristics by phase transition, and so on. As the thermal recording materials of the foregoing kind have advantages of providing recorded images on a dry and simple processing system and requiring practically no maintenance, they are widely used as output materials of various kinds of recording apparatus, such as a printer, a word processor and facsimile. The methods adopted for application of thermal energy are broadly classified into two groups, a laser-using group and a thermal printer head-using group. The former group of methods can provide high-definition images, but on the other hand, they require a considerable cost of hardware and a large-scale apparatus. In contrast, the latter group of methods which use a thermal printer head clear up the foregoing problems. As to the image quality, the demand covers a wide range, from high to low image quality. In cases where high image quality is not particularly required, therefore, the thermal printer head-using methods are useful because of their merits mentioned above.
With respect to the recording materials in which images can be recorded with a thermal printer head, the graphic arts materials of the kind which form images by causing a reaction between an organic silver salt and a reducing agent when heat is applied thereto are disclosed, e.g., in JP-A-8-58239 and JP-A-8-276664 (the term “JP-A” as used herein means an “unexamined published Japanese patent application”). However, the silver salts contained therein have some sensitivity to light, so that one problem of those materials is that special care is required not only upon storage in daylight but also for avoiding light at the time they are used, and another problem thereof is how the recovery of silver source and the disposal of waste materials are carried forward.
The recording materials which utilize silver salt-free (nonsilver) heat-sensitive recording method to settle the aforementioned problems are described in JP-A-11-70735, JP-A-11-70736, JP-A-11-70742 and JP-A-11-70733. Therein is employed the way of isolating leuco dyes from a color developer by heat-responsive capsules and causing color development by thermal penetration. However, those materials have a drawback of being unsatisfactory in developed color densities. Under those circumstances, no recording materials satisfactory in both color developability and processability have been found yet, and so the development of a recording material having both the abilities has been desired.
Further, the problem common to the recording methods using a thermal printer head is that the thermal printer head is smeared and causes sticking, so that it is necessary to improve such conditions.
SUMMARY OF THE INVENTION
Therefore, a first object of the present invention is to provide a highly heat-sensitive material suitable for recording with a thermal printer head and a method of recording images in such a material by means of a thermal printer head.
A second object of the present invention is to provide a heat-sensitive recording material which can be handled and kept safely in daylight and can develop colors of high densities.
A third object of the present invention is to provide a recording material which does not require troublesome treatments for disposal of the used recording material, including the recovery of silver.
A fourth object of the present invention is to provide a recording material which is improved in the extent to which a thermal printer head is smeared and causes sticking.
The foregoing objects of the present invention are attained according to the embodiments (1) to (10) as described below:
(1) An image forming method comprising forming images in an image-forming material by means of a thermal printer head, wherein the image-forming material comprises a compound capable of releasing a strong acid under the action of heat and a compound capable of forming a dye by the reaction with an acid.
(2) The image forming method as described in Embodiment (1), wherein the image-forming material is free of silver.
(3) The image forming method as described in Embodiment (1) or (2) , wherein the compound capable of releasing a strong acid is a compound represented by the following formula (I):
W
1
OP
1
(I)
wherein W
1
represents a moiety to constitute the acid of formula W
1
OH, and P
1
represents a substituent group eliminable by the action of heat or an acid.
(4) The image forming method as described in Embodiment (3) wherein the compound of formula (I) is a compound represented by the following formula (II), (III) or (IV):
wherein R
1
represents an electron-attracting group having a Hammett's &sgr;
P
value greater than 0, R
2
represents an alkyl group, R
3
represents a group eliminable by the action of heat or an acid, and W
1
has the same meaning as in formula (II);
wherein R
4
, R
5
and R
6
each represent a hydrogen atom, an alkyl group or an aryl group, and W
1
has the same meaning as in formula (I); and
P
2
—X—L—C(R
7
) (R
8
)—OW
1
(IV)
wherein P
2
represents a substituent group eliminable by the action of heat or an acid, X represents O, S, NR
9
or CR
10
R
11
wherein R
9
is a hydrogen atom or a group substitutable for hydrogen atom and R
10
and R
11
, which may be the same or different, each represents a hydrogen atom or a group substitutable for hydrogen atom, L represents a linkage group, R
7
and R
8
, which may be the same or different, each represents a hydrogen atom or a group substitutable for hydrogen atom, and W
1
has the same meaning as in formula (I).
(5) The image forming method as described in any one of Embodiments (1) to (4), wherein the compound capable of forming a dye by the reaction with an acid is a compound capable of undergoing a change in the absorption region of 360 to 900 nm when an acid acts thereon.
(6) The image forming method as described in any one of Embodiments (1) to (5), wherein the compound capable of releasing a strong acid under the action of heat and/or the compound capable of forming a dye by the reaction with an acid is a polymer comprising both a partial structure capable of functioning as an acid generator under heating or in the presence of an acid and a partial structure capable of undergoing a change in the absorption region of 360 to 900 nm when an acid acts thereon.
(7) The image forming method as described in Embodiment (6), wherein the polymer is a polymer represented by the following formula (V):
—(A)
x
—(B)
y
—(C)
z
— (V)
wherein A represents a constitutional unit repeated in the polymerization of at least one vinyl monomer functioning as an acid generator by the action of heat or an acid; B represents a constitutional unit repeated in the polymerization of at least one vinyl monomer having a partial structure undergoing a change in the absorption region of 360-900 nm when an acid acts thereon; C represents a constitutional unit repeated in the polymerization of at least one viny
Barlow John
Fuji Photo Film Co. , Ltd.
Shah Manish
Sughrue & Mion, PLLC
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