U.S. patent application number 09/842629 was filed with the patent office on 2002-01-24 for method for forming an image.
Invention is credited to Hatakeyama, Akira, Kawagoe, Shigeki, Konno, Takeshi, Miyake, Kazuhito, Wachi, Naotaka.
Application Number | 20020009664 09/842629 |
Document ID | / |
Family ID | 26591110 |
Filed Date | 2002-01-24 |
United States Patent
Application |
20020009664 |
Kind Code |
A1 |
Wachi, Naotaka ; et
al. |
January 24, 2002 |
Method for forming an image
Abstract
A method for forming an image using a transfer material and an
image-receiving material. The transfer material has at least a
support, a light-heat exchange layer and a coloring material layer.
The image-receiving material has at least an image-receiving layer.
The coloring material layer is superposed on the image-receiving
layer, and laser light is imagewasely irradiated onto this laminate
from the transfer material side. An irradiated region of the
coloring material layer transfers onto the image-receiving layer.
The transfer material may include an electroconductive layer, and
the surface of the coloring material layer may be charged by corona
discharge before superposition. Moreover, yellow, magenta, cyan and
black may be used one after another, The laser light may be
irradiated from a multi-beam 2-dimensional laser array, The
thickness of black coloring material layer is from 0.5 to 0.7 .mu.m
and is greater than the thickness of other coloring material
layers.
Inventors: |
Wachi, Naotaka;
(Shizuoka-ken, JP) ; Miyake, Kazuhito;
(Shizuoka-ken, JP) ; Konno, Takeshi;
(Shizuoka-ken, JP) ; Hatakeyama, Akira;
(Shizuoka-ken, JP) ; Kawagoe, Shigeki;
(Shizuoka-ken, JP) |
Correspondence
Address: |
SUGHRUE, MION, ZINN,
MACPEAK & SEAS, PLLC
Suite 800
2100 Pennsylvania Avenue, N.W.
Washington
DC
20037-3213
US
|
Family ID: |
26591110 |
Appl. No.: |
09/842629 |
Filed: |
April 27, 2001 |
Current U.S.
Class: |
430/200 ;
430/945; 430/964 |
Current CPC
Class: |
Y10S 430/153 20130101;
Y10S 430/146 20130101; B41M 5/42 20130101; Y10S 430/165 20130101;
G03F 3/105 20130101; B41M 5/345 20130101 |
Class at
Publication: |
430/200 ;
430/945; 430/964 |
International
Class: |
G03F 007/34; G03F
007/38 |
Foreign Application Data
Date |
Code |
Application Number |
May 23, 2000 |
JP |
2000-150875 |
Apr 28, 2000 |
JP |
2000-129445 |
Claims
What is claimed is:
1. A method for forming an image, the method comprising the steps
of: charging, by corona discharge, a coloring material layer
surface of a transfer material, which has at least a
light-transmissive support, a light-transmissive electroconductive
layer, a light-heat exchange layer and a coloring material layer;
thereafter superposing an image-receiving layer surface of an
image-receiving material, which has at least a support and an
image-receiving layer, with the coloring material layers surface;
and irradiating laser light imagewisely onto the transfer material,
thereby transferring an irradiated portion of the coloring material
layer of the transfer material to the image-receiving layer
surface, for forming the image on the image-receiving layer surface
of the image-receiving material.
2. The method for forming an image according to claim 1, wherein
the image-receiving material has at least the support, an
electroconductive layer and the image-receiving layer.
3. The method for forming an image according to claim 1, wherein
surface resistivity of the light-transmissive electroconductive
layer of the transfer material is at most 10.sup.11
.OMEGA./.quadrature., and surface resistivity of a side of the
transfer material, which side touches the image-receiving material,
is at least 10.sup.11 .OMEGA./.quadrature..
4. The method for forming an image according to claim 2, wherein
surface resistivity of the electroconductive layer of the
image-receiving material is at most 10.sup.11
.OMEGA./.quadrature..
5. The method for forming an image according to claim 2, wherein a
thickness distance from the coloring material layer surface to the
light-transmissive electroconductive layer of the transfer material
is at least equal to a thickness distance from the image-receiving
layer surface to the electroconductive layer of the image-receiving
material.
6. The method for forming an image according to claim 1, wherein
the step of charging by corona discharge is a corotron charging
process.
7. The method for forming an image according to claim 2, wherein
surface resistivity of the light-transmissive electroconductive
layer of the transfer material is at most 10.sup.11
.OMEGA./.quadrature., and surface resistivity of a side of the
transfer material, which side touches the image-receiving material,
is at least 10.sup.11 .OMEGA./.quadrature..
8. The method for forming an image according to claim 7, wherein
surface resistivity of the electroconductive layer of the
image-receiving material is at most 10.sup.11
.OMEGA./.quadrature..
9. The method for forming an image according to claim 7, wherein a
thickness distance from the coloring material layer surface to the
light-transmissive electroconductive layer of the transfer material
is at least equal to a thickness distance from the image-receiving
layer surface to the electroconductive layer of the image-receiving
material.
10. The method for forming an image according to claim 2, wherein
the step of charging by corona discharge is a corotron charging
process.
11. A method for forming a multi-color image, the method comprising
the steps of: providing an image-receiving material, which has an
image-receiving layer, and four transfer materials, of yellow,
magenta, cyan and black, each of which has, on a support, at least
a light-heat conversion layer and a coloring material layer;
opposing and superposing the coloring material layer of each
transfer material with the image-receiving layer of the
image-receiving material; and irradiating laser light, which is a
multi-beam 2-dimensional array of laser beams, from a support side
of the each transfer material, thereby transferring a laser-light
irradiated region of the coloring material layer of the each
transfer material onto the image-receiving layer of the
image-receiving material, for recording the image, wherein layer
thickness of the coloring material layer of the black transfer
material is greater than layer thickness of the coloring material
layer of each of the yellow, magenta and cyan transfer materials,
and the layer thickness of the coloring material layer of the black
transfer material is from 0.5 to 0.7 .mu.m.
12. The method for forming a multi-color image according to claim
11, wherein the laser light is semiconductor laser light.
13. The method for forming a multi-color image according to claim
11, wherein optical density at 830 nm of the light-heat exchange
layer is 0.7 to 1.1.
14. The method for forming a multi-color image according to claim
11, wherein the coloring material layer of the black transfer
material contains carbon black.
15. The method for forming a multi-color image according to claim
14, wherein the carbon black is composed of at least two kinds of
carbon black, which are different in tinting strength.
16. The method for forming a multi-color image according to claim
11, wherein the layer thickness of the coloring material layer of
each of the yellow, magenta and cyan transfer materials is from 0.2
to 0.5 .mu.m.
17. The method for forming a multi-color image according to claim
12, wherein optical density at 830 nm of the light-heat exchange
layer is 0.7 to 1.1.
18. The method for forming a multi-color image according to claim
12, wherein the coloring material layer of the black transfer
material contains carbon black.
19. The method for forming a multi-color image according to claim
18, wherein the carbon black is composed of at least two kinds of
carbon black, which are different in tinting strength.
20. The method for forming a multi-color image according to claim
12, wherein the layer thickness of the coloring material layer of
each of the yellow, magenta and cyan transfer materials is from 0.2
to 0.5 .mu.m.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a method for forming an
image of high resolution by transferring an image from a transfer
material onto the surface of an image-receiving material using
laser light.
[0003] 2. Description of the Related Art
[0004] Heretofore, a system of directly pressurizing and heating a
heat transfer material with a thermal head has been applied as a
method for recording an image by heat transfer. This system has
superior characteristics in that it is a maintenance-free dry
process that can be implemented with low noise and simple device
structure. The thermal head itself has become more highly dense
and, even in this system, image resolution has been achieved at
considerably higher levels in recent years.
[0005] On the other hand, a laser heat transfer recording system of
irradiating a transfer material with laser light, converting the
laser light into heat in the transfer material and conducting
heat-sensitive recording by said heat has been known as a method of
recording an image of higher resolution by heat transfer. In such a
system, the laser light, being a source of supplying energy, can be
collected to within several microns, thus enabling a significant
improvement in resolution compared with the system using the
thermal head.
[0006] In the field of graphic art, a printing plate is printed by
use of a set of color separation films prepared from a color
original using litho-film. Generally a color proof is prepared from
the color separation films in order to check for errors in a color
separation step, for necessity of color correction before printing
(actual printing operation), and the like. In the color proof,
there is a need for realization of a high resolving power capable
of good reproduction of a halftone image and for characteristics
such as high process stability. Further, to obtain a color proof
resembling an actual print, the materials used in the color proof
are preferably those materials used in the actual printing; for
example, it is preferable to use regular printing paper as a
support and pigment as a coloring material. Further, a dry process
using no developing solution is strongly desired as the method of
preparing a color proof.
[0007] As the dry process for preparing a color proof, a recording
system of preparing a color proof directly from digital signals has
been developed in accordance with the recent spread of electronic
systems for pre-processes in printing (the preliminary press
field). The object of such an electronic system is to prepare a
color proof of particularly high quality, generally to reproduce a
halftone-point image of at least 150 lines/inch. For recording a
high-quality proof from digital signals, a laser light that can be
modulated with digital signals and a device capable of narrowing
down a recording light are used as a recording head. Accordingly,
it is necessary to develop a recording material showing high
recording sensitivity toward laser light and showing high resolving
power so as to be capable of reproducing halftone points highly
accurately.
[0008] As the transfer material used in the laser heat transfer
recording system, a heat-fusion transfer material is known that
has, on a support in this order, a light-heat exchange layer that
absorbs laser light to generate heat and an coloring material layer
that has a pigment dispersed in components such as heat-fusion wax,
a binder and the like (Japanese Patent Application Laid-Open (JP-A)
No. 5-58045 and the like). When such a heat-fusion transfer
material is used, heat generated in a laser light-irradiated region
of the light-heat exchange layer causes the coloring material layer
corresponding to that region to be melted and transferred onto an
image-receiving material that has been superposed on the
heat-fusion transfer material, thereby forming a transferred image
on the image-receiving material.
[0009] JP-A NO. 6-219052 describes an image-forming method which
includes forming a highly accurate image on an image-receiving
material superposed on a transfer material that has a light-heat
exchange layer containing a light-heat exchange material, a very
thin (0.03 to 0.3 .mu.m) thermally releasable layer, and a coloring
material layer containing a coloring material arranged in this
order on a support. In this method, a binding force between the
coloring material layer and the light-exchange layer, which are
bound via the thermally releasable layer, is reduced by irradiation
with laser light. In this image-forming method, so-called
"abrasion" is utilized. Specifically, the thermally releasable
layer is partially decomposed and gasified in a region irradiated
with laser light, thus weakening the binding force between the
coloring material layer and the light-heat exchange layer in that
region, and permitting the coloring material layer in that region
to be transferred onto the image-receiving material superposed on
the transfer material, thereby forming a transferred image on the
image-receiving material.
[0010] An image-forming method utilizing laser light has advantages
such as usability of regular printing paper provided with an
image-receiving layer (adhesive layer) as the image-receiving
material, easy provision of a multi-color image by successive
transfer of images of different colors onto the image-receiving
material, and the like. In particular, an image-forming method
utilizing abrasion has the advantage of easy provision of a highly
accurate image, and is particularly useful for forming a color
proof (direct digital color proof (DDCP)) or a highly accurate mask
image.
[0011] In these methods of forming an image by heat transfer, the
resolution of the image is significantly influenced by adhesion
between the transfer material and the image-receiving material
during transfer of the image. Thus, increasing the adhesion between
the two is a key to achieving high-resolution images.
[0012] As a method of increasing the adhesion between the transfer
material and the image-receiving material, a method in which the
transfer material and/or the image-receiving material is provided
with a cushion layer endowed with flexibility, to absorb unevenness
between the two, has been disclosed (JP-A No. 5-169861).
[0013] However, if the image-receiving material is provided with
the cushion layer, it is hard to use the image-receiving material
as a final recording medium. Thus a step of transferring an image
formed on the image-receiving material onto a final recording
medium is necessitated, which causes the problem of a complicated
process. Further, if the transfer material is provided with the
cushion layer and the image-receiving material is used as a final
recording medium, there will be cases where unevenness of the
surface of the final recording medium cannot be sufficiently
absorbed by the cushion layer. Thus, there is a need for an
image-forming method capable of forming a high-quality image with
high resolution even if adhesion between the transfer material and
the image-receiving material is not quaranteed.
[0014] Further, in recent years, in order to reduce recording time
when recording an image with laser light, a laser light consisting
of a multi-beam two-dimensional array, in which a plurality of
laser beams is used, has been used. When recording on a
conventional heat transfer sheet with a laser light in a multi-beam
two-dimensional array, there are cases where the density of the
transferred image formed on the image-receiving sheet becomes
insufficient. In particular, the density of the image is
significantly reduced in the case of laser recording with high
energy. As a result of investigations, by the inventors of the
present invention, it was found that this reduction in the density
of the image is caused by uneven transfer occurring in laser
recording with high energy.
SUMMARY OF THE INVENTION
[0015] Accordingly, an object of the present invention is to
provide an image-forming method capable of forming a transferred
image having high resolution, high quality and good color tones,
without parts missing from the image, even if a transfer material
and an image-receiving material are not provided with a cushion
layer.
[0016] Another object of the present invention is to provide a
method for forming a multi-color image which method can form a
high-quality image with stable transfer density on an
image-receiving sheet, even if laser recording is conducted with
high-energy by a laser beam in a multi-beam two-dimensional array
under various temperature and humidity conditions.
[0017] A first aspect of the invention is a method for forming an
image, the method comprising the steps of: charging, by corona
discharge, a coloring material layer surface of a transfer
material, which has at least a light-transmissive support, a
light-transmissive electroconductive layer, a light-heat exchange
layer and a coloring material layer; thereafter superposing an
image-receiving layer surface of an image-receiving material, which
has at least a support and an image-receiving layer, with the
coloring material layers surface; and irradiating laser light
imagewisely onto the transfer material, thereby transferring an
irradiated portion of the coloring material layer of the transfer
material to the image-receiving layer surface, for forming the
image on the image-receiving layer surface of the image-receiving
material.
[0018] A second aspect of the invention is a method for forming a
multi-color image, the method comprising the steps of: providing an
image-receiving material, which has an image-receiving layer, and
four transfer materials, of yellow, magenta, cyan and black, each
of which has, on a support, at least a light-heat conversion layer
and a coloring material layer; opposing and superposing the
coloring material layer of each transfer material with the
image-receiving layer of the image-receiving material; and
irradiating laser light, which is a multi-beam 2-dimensional array
of laser beams, from a support side of the each transfer material,
thereby transferring a laser-light irradiated region of the
coloring material layer of the each transfer material onto the
image-receiving layer of the image-receiving material, for
recording the image, wherein layer thickness of the coloring
material layer of the black transfer material is greater than layer
thickness of the coloring material layer of each of the yellow,
magenta and cyan transfer materials, and the layer thickness of the
coloring material layer of the black transfer material is from 0.5
to 0.7 .mu.m.
BRIEF DESCRIPTION OF THE DRAWINGS
[0019] FIG. 1 is a perspective view showing the concept of an
image-forming method of the present invention.
[0020] FIG. 2 is a sectional view showing an example of an
image-receiving material and a transfer material used in the
present invention.
[0021] FIGS. 3A to 3C are sectional views showing an outline of a
step in a method of forming a multi-color image of the present
invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0022] Hereinafter, a method for forming an image of the present
invention is described with reference to the drawings. FIG. 1 is a
conceptual drawing showing the method for forming an image of the
present invention. In FIG. 1, 10 indicates a transfer material
having an electroconductive layer 14, 20 indicates an
image-receiving material, 40 indicates a recording drum and 30
indicates a corotron charger using a wire, which is one kind of
corona charger. The image-receiving material is placed closely on
the recording drum 40. Before the transfer material is transported
onto the image-receiving material, a coloring material layer
surface is corona-charged. After being charged, the charged
transfer material is transported and laid over the image-receiving
material 20. Then this arrangement is subjected to imagewise
irradiation with a laser in time series from a transfer material
side (see FIG. 2). Thus, the coloring material layer is
transferred. Thereafter, the image-receiving material is peeled
from the transfer material.
[0023] FIG. 2 shows a sectional structure of one example of the
transfer material and the image-receiving material. In this
example, the transfer material 10 consists of an electroconductive
layer 2, a support 4, a light-heat exchange layer 6 and a coloring
material layer 8, while the image receiving material 20 consists of
a support 12, an electroconductive layer 14 and an image-receiving
layer 16.
[0024] By this method, a high-quality image free of missing parts
can be obtained.
[0025] An outline of a multi-color image-forming method in a second
aspect of the invention is described with reference to FIGS. 3A to
3C.
[0026] An image-forming laminate 130 having an image-receiving
sheet 120 superposed on a surface of a coloring material layer 116
of a transfer material 110 is prepared. The transfer material 110
has a support 112 with a light-heat exchange layer 114 and the
coloring material layer 116 in that order thereon. The image
receiving sheet 120 has a support 122 with an image-receiving layer
124 thereon. The image-receiving layer 124 is laminated so as to be
in contact with the surface of the coloring material layer 116 of
the transfer material 110 (FIG. 3A). Upon imagewise irradiation
with a laser light in time series onto the support 112 side of the
transfer material 110 in the laminate 130, a laser light-irradiated
region of the light-heat exchange layer 114 of the transfer
material 110 generates heat, which lowers adhesion between the
light-heat exchange layer 114 and the coloring material layer 116
(FIG. 3B). Thereafter, when the image-receiving sheet 120 is peeled
from the transfer material 110, a laser light-irradiated region
116' of the coloring material layer 116 is transferred onto the
image-receiving layer 124 of the image-receiving sheet 120 (FIG.
3C).
[0027] Below, the transfer material and the image-receiving sheet
used in the image-forming method of the present invention are
described.
[0028] Transfer material
[0029] The transfer material used in the present invention has at
least a light-heat exchange layer and an coloring material layer on
a support, and other layers as necessary (an electroconductive
layer, a cushion layer, a heat-sensitive release layer, a light
reflection-preventing layer, and the like).
[0030] Support
[0031] A material of the support of the transfer material is not
particularly limited, and a wide variety of support materials can
be used depending on objectives. Preferable examples of such
support materials include synthetic resin materials such as
polyethylene terephthalate, polyethylene-2,6-naphthalate,
polycarbonate, polyethylene, polyvinyl chloride, polyvinylidene
chloride, polystyrene, styrene-acrylonitrile copolymers and the
like. Among these, biaxially oriented polyethylene terephthalate is
preferable in consideration of mechanical strength and dimensional
stability in response to heat. If the transfer material is to be
used in preparation of a color proof utilizing laser recording or
in the image-forming method of the first aspect of the invention,
the support for the transfer material is preferably formed from a
transparent synthetic resin material that will permit laser light
to pass therethrough.
[0032] To improve adhesion to a layer provided thereon, the support
for the transfer material may be subjected to a surface activation
treatment and/or provided with one or more undercoat layers.
Examples of the surface activation treatment include glow discharge
treatment, corona discharge treatment and the like. A material for
the undercoat layer is preferably a material showing strong
adhesion to both the surface of the support and the surface of the
layer thereon, having low thermal conductivity and being excellent
in heat resistance. Examples of such materials for the undercoat
layer include polystyrene, styrene-butadiene copolymer, gelatin and
the like. The total thickness of the undercoat layers is usually
0.01 to 2 .mu.m. A side of the transfer material opposite to the
side on which the light-heat exchange layer is provided may be
provided with various functional layers thereon, such as a
reflection-preventing layer and an antistatic layer, as necessary,
or can be subjected to surface treatment.
[0033] Electroconductive layer
[0034] The transfer material used in the image-forming method of
the first aspect of the present invention has an electroconductive
layer on the support.
[0035] The electroconductive layer in the transfer material
includes a layer including of, for example, an electroconductive
material and a binder. Examples of the electroconductive material
include tin oxide, polyethylene glycol, carbon black, surfactants,
inorganic salts and the like. Of these, fine particles of tin oxide
doped with antimony, as described in JP-A No. 61-20033, are
preferably used. Needle-like fine particles of tin oxide, described
in JP-A No. 11-15109, are more preferable. As the binder, a binder
as described in the below section describing the light-heat
exchange layer is preferably used. The electroconductive layer is
formed by coating and drying a coating solution prepared with the
electroconductive material and the binder in a suitable
solvent.
[0036] The thickness of the electroconductive layer is 0.01 to 2
.mu.m, preferably 0.05 to 0.15 .mu.m. If the thickness is less than
0.01 .mu.m, the electroconductive layer will be susceptible to the
influence of temperature and humidity, leading to unstable
electrical conductivity. On the other hand, if the thickness is
greater than 2 .mu.m, transparency of the transfer material is
likely to be lowered. Accordingly, the thickness of the
electroconductive layer is suitably in the range described
above.
[0037] Surface resistivity of the electroconductive layer is
preferably not greater than 10.sup.11 .OMEGA./.quadrature.. If the
surface resistivity is greater than 10.sup.11 .OMEGA./.quadrature.,
charging by corona charging will be difficult. Preferably, the
surface resistivity is not greater than 10.sup.9
.OMEGA./.quadrature..
[0038] The position of the electroconductive layer in the transfer
material is not particularly limited, but it is preferable that the
electroconductive layer is provided at the support side of the
light-heat exchange layer so that, upon lamination onto the
image-receiving material, the corona-charged transfer material
attains good adhesion to the image-receiving material.
[0039] Further, it is preferable in the image-forming method of the
first aspect of the present invention that the image-receiving
material is also provided with the electroconductive layer. In this
case, a thickness distance from the surface of the coloring
material layer to the electroconductive layer in the transfer
material is preferably equal to or greater than a thickness
distance from the surface of the image-receiving layer to the
electroconductive layer in the image-receiving material.
Accordingly, a preferably used transfer material has, for example,
the electroconductive layer provided on one surface of the
light-transmissive support, and the light-heat exchange layer and
the coloring material layer in that order on the other surface of
the support.
[0040] Light-heat exchange layer
[0041] The light-heat exchange layer contains a light-heat exchange
material, a binder resin and, as necessary, a matting material and
other components.
[0042] The light-heat exchange material is a material having the
facility to convert irradiated light energy into heat energy.
Generally, the material is a colorant capable of absorbing laser
light (possibly a pigment; this applies hereinafter). In a case of
recording an image with an infrared laser, the light-heat exchange
material used is preferably a colorant that absorbs infrared
rays.
[0043] Examples of the colorant (pigment or the like) include
organic colorants and black pigments such as carbon black. In the
present invention, an organic colorant is preferably used in view
of film strength of the light-heat exchange layer.
[0044] Examples of such organic colorants include pigments which
are large cyclic compounds having absorption in the visible to
near-infrared region, such as phthalocyanine and naphthalocyanine;
organic dyes used as laser-absorbing materials for high-density
laser recording on optical disks and the like (cyanine dyes besides
indolenine dyes, anthraquinone dyes, azulene colorants and
phthalocyanine dyes); and organometal compound colorants such as
dithiol-nickel complexes and the like. Among these, the cyanine
colorants are preferable in view of efficiency of light-heat
exchange and resistance to destruction by laser light. The
light-heat exchange material desirably has a high ability to
exchange light to heat. Indolenine compounds of formula (I)
described in Japanese Patent Application No. 10-140924 can be
mentioned as particularly preferable light-heat exchange
materials.
[0045] As the light-heat exchange material, besides the colorants,
inorganic materials, granular metal materials such as black silver
and the like, can also be used.
[0046] The binder resin contained in the light-heat exchange layer
is preferably a resin having high thermal conductivity and at least
enough strength to form the layer on the support. Further, the
binder resin is preferably a heat-resistant resin that will not be
decomposed even by heat generated by the light-heat exchange
material in recording an image, so that the light-heat exchange
layer, even when irradiated with light of high energy, can maintain
its surface smoothness after light irradiation. Specifically, a
resin having a thermal decomposition temperature (a temperature at
which weight of the resin is reduced by 5% in an air stream with
temperature increasing at 10.degree. C./min in the TGA method) of
not less than 400.degree. C. is preferable, and a resin with a
thermal decomposition temperature of not less than 500.degree. C.
is more preferable. Further, the binder resin preferably has a
glass transition temperature of from 200 to 400.degree. C., more
preferably from 250 to 350.degree. C. If the glass transition
temperature is lower than 200.degree. C., fogging may occur on the
formed image, while if the same is higher than 400.degree. C.,
solubility of the resin may be lowered, lowering the efficiency of
production.
[0047] The heat resistance (e.g., thermal deformation temperature
and thermal decomposition temperature) of the binder resin in the
light-heat exchange layer is preferably higher than that of
materials used in other layers formed on the light-heat exchange
layer.
[0048] Examples of such a binder include homopolymers and
copolymers of acrylic monomers such as acrylic acid and the like
(e.g. poly(methyl methacrylate)); cellulose polymers such as
cellulose acetate and the like; polycarbonate; polystyrene; vinyl
polymers such as vinyl chloride/vinyl acetate copolymers; polyvinyl
butyral, polyvinyl alcohol, polyvinyl chloride and the like;
condensed polymers such as polyester, polyamide, polyimide and the
like; polyether imide; polysulfone; polyether sulfone; aramide;
rubber-type thermoplastic polymers such as butadiene/styrene
copolymers; polyurethane; epoxy resin; urea/melamine resin and the
like. Among these, polymers such as polyvinyl alcohol, polyvinyl
butyral, polyester and polyimide are preferably used. As a
particularly preferable binder, a polyimide resin described in
Japanese Patent Application No. 10-140924 can be mentioned.
[0049] Further, the polyimide resins represented by formulae (I) to
(VII) below are soluble in an organic solvent, and use of these
polyimide resins is preferable because productivity of the transfer
material is improved. Also, use of these is further preferable in
view of improvement of viscosity stability, long-term stability and
moisture resistance of a coating solution for the light-heat
exchange layer. 1
[0050] In the formulae (I) and (II) above, Ar.sup.1 represents an
aromatic group represented by the structural formulae (1) to (3)
below, and n is an integer from 10 to 100. 2
[0051] In the formulae (III) and (IV), Ar.sup.2 represents an
aromatic group represented by the structural formulae (4) to (7)
below, and n is an integer from 10 to 100. 3
[0052] In the formulae (V) to (VII) above, n and m are integers
from 10 to 100. In the formula (VI), an n:m ratio is from 6:4 to
9:1.
[0053] A criterion for judging whether the resin is soluble in an
organic solvent or not is whether or not at least 10 parts by
weight of the resin is dissolved in 100 parts by weight of
N-methylpyrrolidone at 25.degree. C. If at least 10 parts by weight
of the resin is dissolved, said resin can be used preferably for
the light-heat exchange layer. A more preferable resin is a resin
which is dissolved in an amount of at least 100 parts by weight in
100 parts by weight of N-methylpyrrolidone.
[0054] A matting agent contained in the light-heat exchange layer
includes inorganic fine particles and organic fine particles.
Examples of inorganic fine particles include metal salts such as
silica, titanium oxide, aluminum oxide, zinc oxide, magnesium
oxide, barium sulfide, magnesium sulfide, aluminum hydroxide,
magnesium hydroxide and boron nitride, as well as kaolin, clay,
talc, zinc white, white lead, zeeklite, quartz, diatomaceous earth,
pearlite, bentonite, mica, synthetic mica and the like. Examples of
organic fine particles include resin particles such as
fluoroplastic particles, guanamine resin particles, acrylic resin
particles, styrene-acrylic acid copolymer resin particles, silicone
resin particles, melamine resin particles, epoxy resin particles
and the like.
[0055] The particle diameter of the matting agent is usually 0.3 to
30 82 m and, preferably 0.5 to 20 .mu.m. The amount of the matting
agent added is preferably 0.1 to 100 mg/m.sup.2.
[0056] A surfactant, a thickening agent, an antistatic agent and
the like may be added to the light-heat exchange layer as
necessary.
[0057] The light-heat exchange layer can be provided by preparing a
coating solution, including the light-heat exchange material, the
binder resin, and, as necessary, the matting agent and other
components, then coating this solution onto the support and drying.
Example of an organic solvent for dissolving the polyimide resin
include n-hexane, cyclohexane, diglyme, xylene, toluene, ethyl
acetate, tetrahydrofuran, methyl ethyl ketone, acetone,
cyclohexanone, 1,4-dioxane, 1,3-dioxolane, dimethyl acetate,
N-methyl-2-pyrrolidone, dimethyl sulfoxide, dimethyl formamide,
dimethyl acetamide, .gamma.-butyrolactone, ethanol, methanol, water
and the like. Coating and drying can be carried out using
conventional coating and drying methods. Drying is carried out
usually at a temperature of 300.degree. C. or less, and preferably
at a temperature of 200.degree. C. or less. If polyethylene
terephthalate is used for the support drying is preferably carried
out at a temperature of 80 to 150.degree. C.
[0058] If the amount of the binder resin in the light-heat exchange
layer is too low, cohesive force of the light-heat exchange layer
will be low and, when a formed image is transferred onto the
image-receiving sheet, the light-heat exchange layer will be easily
transferred together therewith, which will cause color mixture in
the image. On the other hand, if an amount of polyimide resin is
too high, the thickness of the light-heat exchange layer required
for achieving a predetermined light absorptivity will increase,
which will tend to cause a reduction in sensitivity. A ratio by
weight of solid content of the light-heat exchange material to
binder resin in the light-heat exchange layer is preferably from
1:20 to 2:1, and more preferably from 1:10 to 2:1.
[0059] Making the light-heat exchange layer thinner is preferable,
because then the transfer material can be rendered highly
sensitive. The thickness of the light-heat exchange layer is
preferably 0.03 to 1.0 .mu.m, more preferably 0.03 to 0.8 .mu.m,
further preferably 0.05 to 0.5 .mu.m and particularly preferably
0.05 to 0.3 .mu.m. Further, a maximum absorption wavelength of the
light-heat exchange layer is preferably in the range of 700 to 1500
nm, and more preferably in the range of 750 to 1000 nm. Absorbance
(optical density) at these wavelengths is preferably in the range
of 0.1 to 1.3, and more preferably 0.2 to 1.1. Further preferably,
in order to improve transfer sensitivity of the coloring material
layer, the light-heat exchange layer has an optical density of 0.7
to 1.1, more preferably 0.8 to 1.0, with respect to light of a
wavelength of 830 nm. If the optical density at a wavelength of 830
nm is less than 0.7, the conversion of irradiated light into heat
may become unsatisfactory, resulting in a reduction in transfer
sensitivity. On the other hand, if the optical density exceeds 1.1,
the function of the light-heat exchange layer during recording may
be influenced, causing fogging.
[0060] Coloring material layer
[0061] The coloring material layer contains at least a colorant to
be transferred onto the image-receiving sheet to form an image, and
further contains a binder resin for forming the layer and, as
necessary, other components.
[0062] In an image-forming method of the first aspect of the
present invention, surface resistivity of the coloring material
layer, that is, the surface resistivity of the transfer material at
a side thereof in contact with the image-receiving material, is
preferably set at 10.sup.11 .OMEGA./.quadrature. or more. This is
preferable because if the surface resistivity is lower than this
range, when corona-charging the surface of the coloring material
layer, the charge will be leaked immediately and thus the effect of
charging will be lost.
[0063] Generally, colorants can be roughly divided into organic
colorants and inorganic colorants. The former are excellent in
transparency of a coating, while the latter are generally excellent
in shielding properties and the like. Thus, depending on the
intended use, suitable selection can be made. If the transfer
material is to be used for proof of printing colors, organic
colorants corresponding to or near in color tone to yellow,
magenta, cyan and black, which are generally used in printing inks,
can be preferably used. Besides thus, there are also cases where
metal powder or fluorescent pigments can be used. Examples of
preferably used colorants include azo colorants, phthalocyanine
colorants, anthraquinone colorants, dioxazine colorants,
quinacridone colorants, isoindolinone colorants, and nitro
colorants. Pigments that can be used in the coloring material layer
include, but are not limited to, the following listed pigments,
which are classified depending on hue.
[0064] 1) Yellow pigments
[0065] Hansa yellow G, Hansa yellow 5G, Hansa yellow 10G, Hansa
yellow A, pigment yellow L, permanent yellow NCG, permanent yellow
FGL, permanent yellow HR, titanium yellow.
[0066] 2) Red pigments
[0067] Permanent red 4R, permanent red F2R, permanent red FRL, lake
red C, lake red D, pigment scarlet 3B, Bordeaux 5B, alizarine lake,
rhodamine lake B.
[0068] 3) Blue pigments
[0069] Phthalocyanine blue, Victoria blue lake, Fast sky blue.
[0070] 4) Black pigments
[0071] Carbon black, titanium black.
[0072] The average diameter of pigment particles is preferably 0.03
to 1 .mu.m, more preferably 0.05 to 0.5 .mu.m.
[0073] If the diameter is less than 0.3 .mu.m, dispersion cost may
increase and the dispersion may gel or the like. If the diameter is
greater than 1 .mu.m, large-sized particles may impair adhesion
between the coloring material layer and the image-receiving
layer.
[0074] In the present invention, it is preferable, in view of color
tone of a printed image, that an organic colorant to be added to
the light-heat exchange layer is substantially not contained in the
coloring material layer. In the present invention, the phrase "the
organic colorant is substantially not contained in the coloring
material layer" means that the optical density of the organic
colorant is not more than 5% of total optical density (including
optical density of the support) at a wavelength at which an
absorption peak of the transmission optical density of the coloring
material layer occurs.
[0075] The binder resin in the coloring material layer is
preferably an amorphous organic polymer having a softening point of
40 to 150.degree. C. Examples of amorphous organic polymers include
butyral resin; polyamide resin; polyethylene-imine resin;
sulfonamide resin; polyester-polyol resin; petroleum resin;
homopolymers and comopolymers of styrene and derivatives thereof
such as styrene, vinyltoluene, .alpha.-methylstyrene,
2-methylstyrene, chlorostyrene, vinylbenzoic acid, sodium
vinylbenzenesulfonate, aminostyrene and the like; and homopolymers
of methacrylic acid and methacrylates (e.g. methyl methacrylate,
ethyl methacrylate, butyl methacrylate, and hydroxyethyl
methacrylate) and acrylic acid and acrylates (e.g. methyl acrylate,
ethyl acrylate, butyl acrylate and .alpha.-ethyl hexyl acrylate),
dienes (e.g. butadiene and isoprene) acrylonitrile, vinyl ethers,
maleic acid and maleates, maleic anhydride, cinnamic acid, vinyl
monomers (e.g. vinyl chloride and vinyl acetate), and copolymers
thereof with other monomers or the like. These resins can also be
used in a mixture of the two or more thereof.
[0076] The coloring material layer preferably contains 30 to 70% by
weight of the colorant, and the colorant is preferably contained in
an amount of 40 to 60% by weight in the image-forming method in the
first aspect of the present invention and in an amount of 30 to 50%
by weight in the image-forming method in the second aspect. The
coloring material layer preferably contains 70 to 30% by weight of
the resin, and the resin is preferably contained in an amount of 60
to 40% by weight in the image-forming method in the first aspect
and in an amount of 70 to 40% by weight in the image-forming method
in the second aspect.
[0077] The coloring material layer can contain the following
components (1) to (3) as the other components:
[0078] (1) Wax
[0079] Example waxes include mineral waxes, natural waxes and
synthetic waxes. Preferable examples of mineral waxes include
petroleum waxes such as paraffin wax, microcrystalline wax, ester
wax, oxidized wax and the like, as well as montan wax, ozokerite,
ceresin and the like. Among these, paraffin wax is preferable.
Paraffin wax is separated from petroleum and, depending on melting
point, various kinds of paraffin wax are commercially
available.
[0080] Examples of natural waxes include vegetable waxes such as
carnauba wax, Japan wax, ouricury wax, and espal wax and the like,
as well as animal waxes such as beeswax, insect wax, shellac wax,
spermaceti and the like.
[0081] The synthetic waxes are used generally as lubricants, and
are usually composed of higher fatty acid compounds. Examples of
synthetic waxes include:
[0082] 1) Fatty acid-based wax
[0083] Straight-chain saturated fatty acids represented by the
following formula:
CH.sub.3(CH.sub.2).sub.nCOOH
[0084] wherein n is an integer of 6 to 28. Specific examples
thereof include stearic acid, behenic acid, palmitic acid,
12-hydroxystearic acid, azelaic acid and the like.
[0085] 2) Fatty ester-based wax
[0086] Specific examples of fatty esters include ethyl stearate,
lauryl stearate, ethyl behenate, hexyl behenate, behenyl myristate
and the like.
[0087] 3) Fatty amide-based wax
[0088] Examples of fatty amides include stearic amide, lauric amide
and the like.
[0089] 4) Fatty alcohol-based wax
[0090] Straight-chain saturated fatty alcohols represented by the
following formula:
CH.sub.3(CH.sub.2).sub.nOH
[0091] wherein n is an integer of 6 to 28. Specific examples
thereof include stearyl alcohol and the like.
[0092] Among the synthetic waxes described in 1) to 4) above,
higher fatty amides such as stearic amide and lauric amide are
particularly suitable. The wax compounds mentioned above can be
used singly or in a suitable combination thereof as required.
[0093] (2) Plasticizer
[0094] If a multi-color image is formed by repeatedly overlaying on
the same image-receiving material a large number of image layers
(coloring material layers having an image formed thereon) using a
plurality of transfer materials, the coloring material layer
preferably contains a plasticizer, in order to increase adhesion
between images.
[0095] The plasticizer is preferably an ester compound, and mention
can be made of known plasticizers, for example, phthalates such as
dibutyl phthalate, di-n-octyl phthalate, di(2-ethylhexyl)
phthalate, dinonyl phthalate, dilauryl phthalate, butyl lauryl
phthalate, butyl benzyl phthalate, and the like; aliphatic dibasic
acid esters such as di(2-ethylhexyl) adipate, di(2-ethylhexyl)
sebacate, and the like; phosphoric acid triesters such as such as
tricresyl phosphate, tri(2-ethylhexyl) phosphate and the like;
polyol polyesters such as polyethylene glycol ester and the like;
epoxy compounds such as epoxy fatty esters and the like; and the
like. Among these, esters of vinyl monomers, particularly acrylates
or methacrylates, are preferably added, in respect of improvement
of transfer sensitivity and alleviating transfer unevenness, and of
greater effect of regulating breaking elongation.
[0096] Examples of the acrylates and methacrylates include
polyethylene glycol dimethacrylate, 1,2,4-butanetriol
trimethacrylate, trimethylolethane triacrylate, pentaerythritol
acrylate, pentaerythritol tetraacrylate,
dipentaerythritol-polyacrylate and the like.
[0097] The plasticizer may include polymers, among which polyesters
are preferable in respect of greater effect and resistance to
diffusion under storage conditions. Example polyesters include
sebacic acid-based polyesters, adipic acid-based polyesters and the
like.
[0098] Additives contained in the coloring material layer are not
limited to those described above. Moreover, the plasticizers may be
used singly or in combination.
[0099] If the content of the additives in the coloring material
layer is too high, resolution of the transfer image may be lowered,
film strength of the coloring material layer itself may be lowered,
and transfer to the image-receiving sheet at non-irradiated
portions may occur because of a reduction in adhesion between the
light-heat exchange layer and the coloring material layer. In view
of the foregoing, wax content is preferably 0.1 to 30% by weight,
and more preferably 1 to 20% by weight, based on total solid
content of the coloring material layer. The plasticizer is used
generally in such an amount that a ratio of the total weight of the
colorant and amorphous organic polymer in the coloring material
layer to the plasticizer is in a range from 100:1 to 100:3,
preferably from 100:1.5 to 100:2. Moreover, the content of the
plasticizer is preferably 0.1 to 20% by weight, more preferably 0.1
to 10% by weight, based on the total solid content in the coloring
material layer.
[0100] (3) Other materials
[0101] The coloring material layer may further contain surfactants,
inorganic or organic fine particles (metal powder, silica gel or
the like), oils (linseed oil, mineral oil or the like), thickening
agents, antistatic agents and the like in addition to the
components described above. Except for cases where a black image is
to be obtained, the energy necessary for transfer can be reduced by
incorporation of a material that absorbs at the wavelength of a
light source to be used for recording an image. The material that
absorbs at the wavelength of the light source may be a pigment or a
dye. When a color image is to be obtained, it is preferable for
color reproduction that an infrared light source such as a
semiconductor laser or the like is used for recording the image,
and a dye having considerable absorption at the wavelength of the
light source and less absorption in the visible region is used as
the material. Examples of near infrared dyes include compounds
described in JP-A No. 3-103476.
[0102] The thickness of the coloring material layer (thickness of
the layer when dried) is preferably 0.2 to 1.5 .mu.m, and more
preferably 0.3 to 1.0 .mu.m.
[0103] However, in the multi-color image-forming method of the
second aspect of the invention, the thickness of the coloring
material layer in a black transfer material is characterized by
being greater than the thickness of the coloring material layer in
each of yellow, magenta and cyan transfer materials, and being in
the range of 0.5 to 0.7 .mu.m. With this arrangement, a reduction
in density due to uneven transfer when the black transfer material
is laser-irradiated can be prevented.
[0104] If the thickness of the coloring material layer in the black
transfer material is less than 0.5 .mu.m, density of the image is
significantly lowered due to uneven transfer during recording with
high energy, and thus the image density necessary for a printing
proof cannot be achieved. Because this trend is significant under
high humidity conditions, changes in density due to the environment
become significant. On the other hand, if the layer thickness
exceeds 0.7 .mu.m, the transfer sensitivity is lowered during laser
recording, thus adversely affecting application of small dots and
further thinning thin lines. This trend is more significant under
low humidity conditions. Also, resolving power may deteriorate. The
thickness of the coloring material layer in the black transfer
material is more preferably 0.55 to 0.65 .mu.m, and particularly
preferably 0.60 .mu.m.
[0105] Further, while the thickness of the coloring material layer
in the black transfer material is 0.5 to 0.7 .mu.m, the thickness
of the coloring material layer in each of the yellow, magenta and
cyan transfer materials is preferably equal to or greater than 0.2
.mu.m and less than 0.5 .mu.m.
[0106] If the thickness of the coloring material layer in each of
the yellow, magenta and cyan transfer materials is less than 0.2
.mu.m, there may occur a reduction in density due to uneven
transfer during laser recording, and if the thickness is equal to
or greater than 0.5 m, there may occur a reduction in transfer
sensitivity or a deterioration in resolving power. The thickness is
more preferably 0.3 to 0.45 .mu.m.
[0107] The coloring material layer in the black transfer material
preferably contains carbon black, and more preferably contains at
least two kinds of carbon blacks which are different in tinting
strength, so that reflection density can be controlled while a P/B
(pigment/binder) ratio is maintained in a predetermined range.
[0108] The tinting strength of carbon black is shown by various
methods. For example, PVC blackness, described in JP-A No.
10-140033 and the like, can be mentioned. The PVC blackness is
determined as follows: Carbon black is added to PVC resin,
dispersed by a twin-screw roll and formed into a sheet. The (PVC)
blackness of the sheet is evaluated by visual judgment with
standard points 1 and 10 assigned to the blackness of carbon black
"#40" and carbon black "#45" (Mitsubishi Chemical Corp.),
respectively. In the present invention, two or more kinds of carbon
black which are different in PVC blackness can be suitably selected
and used depending on objectives.
[0109] Hereinafter, a concrete method of preparing a sample is
described.
[0110] Method of preparing a sample
[0111] A 40% by weight sample of carbon black is mixed with LDPE
resin by a 250 cc Banbury mixer and kneaded at 115.degree. C. for 4
minutes.
1 Compounding conditions LDPE resin 101.89 g Calcium stearate 1.39
g IRUGANOX 1010 0.87 g Sample carbon black 69.43 g
[0112] Then, the mixture is diluted at 120.degree. C. by a
twin-screw roll mill such that the concentration of carbon black
becomes 1% by weight.
[0113] Conditions for preparing the diluted compound
2 LDPE resin 58.3 g Calcium stearate 0.2 g Resin mixed with 40 wt.
% carbon black 1.5 g
[0114] The sample is formed into a sheet with a slit width of 0.3
mm, and this sheet is cut into chips and formed into a 65.+-.3
.mu.m film on a hot plate at 240.degree. C.
[0115] The coloring material layer can be provided by preparing a
coating solution having the pigment, the binder resin and the like
dissolved or dispersed therein and coating the coating solution
onto the light-heat exchange layer (or onto a heat-sensitive
release layer, described below, if the same is provided on the
light-heat exchange layer) and drying. Solvents that can be used
for preparing the coating solution include not only those described
above in the section on formation of the light-heat exchange layer
but also n-propyl alcohol, methyl ethyl ketone, propylene glycol
monomethyl ether (MFG), methanol and the like. Coating and drying
can be carried out by utilizing usual coating and drying
methods.
[0116] A heat-sensitive release layer can be provided between the
light-heat exchange layer and the coloring material layer in the
transfer material described above. The heat-sensitive release layer
contains a heat-sensitive material for generating a gas or for
releasing water or the like, by the action of heat generated in the
light-heat exchange layer, thereby weakening adhesion between the
light-heat exchange layer and the coloring material layer. Such a
heat-sensitive material can make use of a compound (a polymer or a
low-molecular compound) which is decomposed or modified in itself
by heating to generate a gas, a compound (a polymer or a
low-molecular compound) which absorbs or adsorbs a considerable
amount of a gas which is easily vaporized, such as water, or the
like. These may be used in combination.
[0117] Examples of polymers that are decomposed or modified by
heating to generate a gas include self-oxidative polymers such as
nitro cellulose; halogen-containing polymers such as chlorinated
polyolefins, chlorinated rubber, poly(rubber chloride), polyvinyl
chloride and polyvinylidene chloride; acrylic polymers such as
polyisobutyl methacrylates and the like having volatile compounds
such as water or the like adsorbed therein; cellulose esters such
as ethyl and cellulose the like having volatile compounds such as
water or the like adsorbed therein, natural polymeric compounds
such as gelatin and the like having volatile compounds such as
water or the like adsorbed therein. Examples of low-molecular
compounds which are decomposed or modified by heating to generate a
gas include compounds such as diazo compounds and azide compounds
which are exothermally decomposed to generate a gas.
[0118] The thermal decomposition or modification of the
heat-sensitive materials as described above occurs preferably at
280.degree. C. or less, more preferably at 230.degree. C. or
less.
[0119] If a low-molecular compound is used as the heat-sensitive
material in the heat-sensitive release layer, it is desirably
combined with a binder. For the binder, it is possible to use the
above-described polymer which is thermally decomposed or modified
in itself to generate a gas, but it is also possible to use a
normal polymer binder not having such properties. If the
heat-sensitive low-molecular compound is used in combination with
the binder, the ratio of the former to the latter is preferably
from 0.02:1 to 3:1, and more preferably from 0.05:1 to 2:1.
Preferably, almost the whole surface of the light-heat exchange
layer is covered with the heat-sensitive release layer, and the
thickness of the heat-sensitive release layer is generally in a
range of 0.03 to 1 .mu.m, preferably 0.05 to 0.5 .mu.m.
[0120] In a case where the transfer material is formed by
laminating the light-heat exchange layer, the heat-sensitive
release layer and the coloring material layer on the support in
that order, the heat-sensitive release layer is decomposed and
modified by heat transmitted from the light-heat exchange layer,
thus generating a gas. By this decomposition or gas generation, a
portion of the heat-sensitive release layer is partially
eliminated, or aggregative destruction occurs in the heat-sensitive
release layer, lowering the binding force between the light-heat
exchange layer and the coloring material layer. Accordingly,
depending on the behavior of the heat-sensitive release layer, a
portion of the heat-sensitive release layer may adhere to the
coloring material layer and appear on the surface of the finally
formed image, which will cause a color mixture in the image.
Accordingly, it is desired that, even if transfer of the
heat-sensitive release layer occurs, the heat-sensitive release
layer is hardly colored (that is, it shows high transmissivity of
visible rays), so as to prevent the occurrence of color mixture in
the formed image. Specifically, the light absorptivity of visible
rays of the heat-sensitive release layer is 50% or less, and
preferably 10% or less.
[0121] Further, the transfer material can also be structured such
that, rather than providing an independent heat-sensitive release
layer, the heat-sensitive material is added to a coating solution
for the light-heat exchange layer, to form a light-heat exchange
layer that serves not only as the light-heat exchange layer but
also as the heat-sensitive release layer.
[0122] In the image-forming method in the first aspect of the
invention, it is preferable that the other side of the support than
the side on which the coloring material layer has been provided is
provided with a light reflection-preventing layer. By providing the
light reflection-preventing layer, disturbance of the image or a
reduction in resolving power due to irregular reflection of light
during a laser-irradiation operation, for imagewise irradiation of
the surface of the transfer material with laser light, can be
prevented.
[0123] The light reflection-preventing layer is generally formed by
laminating materials different in refractive index so as to endow
the layer with the effect of preventing light reflection. By this
method, an effective light reflection-preventing layer can be
prepared. Materials having such effects include sulfides such as
SnS, InS, GeS and the like, oxides of In, Sn, Te, Ga and Si, and
the like.
[0124] To prevent flawing, a protective cover film (e.g., a
polyethylene terephthalate sheet, polyethylene sheet or the like)
can be laminated or the image-receiving material (particularly the
image-receiving material described below) can be formed in advance
on the surface of the coloring material layer of the transfer
material of the present invention.
[0125] Image-receiving material
[0126] The coloring material layer in the transfer material is
subjected to imagewise transfer by irradiation with a laser light
to form an image on the image-receiving material in the present
invention. If the image-receiving material is to be used as a final
transfer medium, any medium, such as general paper, a plastic sheet
or the like, on which an image can be obtained can be used as the
image-receiving material. To obtain a more highly accurate and
highly colored image, it is preferable to use a material whose
surface has been treated as appropriate for an image-receiving
material, to attain suitable conditions for receiving an image
(hereinafter, such an image-receiving material is referred to as
"image-receiving sheet").
[0127] The image-receiving sheet is usually provided with a support
and one or more image-receiving layers on the support and, as
necessary, with one or more of a cushion layer, a release layer and
an intermediate layer between the support and the image-receiving
layer. The presence of a back layer at the opposite side of the
support to the side of the image-receiving layer is preferable in
view of transportability.
[0128] Support
[0129] The support includes a conventional sheet material such as a
plastic sheet, metal sheet, glass sheet, paper or the like.
Examples of plastic sheets include a polyethylene terephthalate
sheet, polycarbonate sheet, polyethylene sheet, polyvinyl chloride
sheet, polyvinylidene chloride sheet, polystyrene sheet,
styrene-acrylonitrile sheet, polyester sheet and the like. As
paper, printing paper, coated paper and the like can be used.
[0130] The support preferably has fine voids to prevent curling and
to improve image quality. Such a support can be prepared, by for
example, mixing a thermoplastic resin with a filler composed of an
inorganic pigment or a polymer or the like that is immiscible with
the thermoplastic resin, and then forming a resulting mixed melt
into a single-layer or multi-layer film with a melt extruder, and
further orienting the film monoaxially or biaxially. In this case,
a degree of voids is determined by selection of the resin and
filler, the mixing ratio thereof, orienting conditions, and the
like.
[0131] As the thermoplastic resin, polyolefin resins such as
polypropylene and the like, and polyethylene terephthalate resin
are preferable because of good crystallinity, good orientability,
and easy formation of voids. It is preferable that the polyolefin
resin or polyethylene terephthalate resin is used as a major
component with which a suitably small amount of an other
thermoplastic resin is used in combination. The inorganic pigment
to be used as the filler preferably has an average particle
diameter of 1 to 20 .mu.m. Calcium carbonate, clay, diatomaceous
earth, titanium oxide, aluminum hydroxide, silica and the like can
be used. As the immiscible resin to be used as the filler,
polyethylene terephthalate is preferably used in a combination
where polypropylene is to be used as the thermoplastic resin.
[0132] The content of the filler in the support, the inorganic
pigment or the like, is generally of the order of 2 to 30% by
volume.
[0133] The thickness of the support of the image-receiving sheet is
usually 10 to 400 .mu.m, and preferably 25 to 200 .mu.m. The
surface of the support may have been subjected to surface
treatments such as corona discharge treatment, glow discharge
treatment and the like in order to improve the adhesion to the
image-receiving layer (or electroconductive layer, or cushion
layer) of the image-receiving sheet or to the coloring material
layer of the transfer material.
[0134] Image-receiving layer
[0135] The surface of the image-receiving sheet is preferably
provided with one or more image-receiving layers on the support in
order to transfer and fix the coloring material layer. The
image-receiving layer is preferably a layer formed from an organic
polymeric binder as the major component. The binder is preferably a
thermoplastic resin, and examples thereof include homopolymers and
copolymers of acrylic monomers such as acrylic acid, methacrylic
acid, acrylates, methacrylates and the like; cellulose polymers
such as methyl cellulose, ethyl cellulose and cellulose acetate;
homopolymers and copolymers of vinyl monomers such as polystyrene,
polyvinyl pyrrolidone, polyvinyl butyral, polyvinyl alcohol,
polyvinyl chloride, and the like; condensed polymers such as
polyester and polyamide; and rubber polymers such as
butadiene-styrene copolymers. The binder in the image-receiving
layer is preferably a polymer having a glass transition temperature
(Tg) of 90.degree. C. or less, in order to achieve suitable
adhesion to the coloring material layer. For this purpose, a
plasticizer can also be added to the image-receiving layer.
Further, the binder polymer preferably has a Tg of 30.degree. C. or
more, in order to prevent blocking among sheets. As the binder
polymer in the image-receiving layer, a polymer identical with or
similar to the binder polymer in the coloring material layer is
particularly preferable, in view of improvement of the adhesion to
the coloring material layer during laser recording and improvement
of sensitivity and image strength.
[0136] If an image is formed on the image-receiving layer and then
re-transferred to regular printing paper or the like, at least one
of the image-receiving layers is preferably formed from a
photosetting material. Example compositions of such a photosetting
material include combinations of a) photo-polymerizable monomers
that are composed of at least one kind of multifunctional vinyl or
vinylidene compound capable of forming a photo-polymerized product
by addition polymerization, b) an organic polymer, and c) a
photo-polymerization initiator, and, as necessary, additives such
as a thermal-polymerization inhibitor. As the multifunctional vinyl
polymer, unsaturated esters of polyol, particularly acrylates or
methacrylates (e.g., ethylene glycol diacrylate or pentaerythritol
tetraacrylate) can be used.
[0137] As the organic polymer, the above polymer for forming the
image-receiving layer can be mentioned. As the photo-polymerization
initiator, usual radical photo-polymerization initiators such as
benzophenone, Michler's ketone and the like can be used in a
proportion of 0.1 to 20% by weight of the layer.
[0138] The thickness of the image-receiving layer is 0.3 to 7
.mu.m, and preferably 0.7 to 4 .mu.m. If the thickness is less than
0.3 .mu.m, the layer will be easily broken during re-transfer to
regular printing paper due to deficient film strength. If the layer
is too thick, glossiness of the image after re-transfer to regular
printing paper will increase, and similarity of the resulting image
to printed matter will be lowered.
[0139] Other layers
[0140] Further, in the image-forming method of the first aspect of
the present invention, the image-receiving material is preferably
provided with an electroconductive layer to improve adhesion
between the transfer material and the image-receiving material.
[0141] Like the electroconductive layer in the transfer material,
the electroconductive layer in the image-receiving material may be
a layer containing an electroconductive material and a binder. As
the binder and the electroconductive material, those used in the
electroconductive layer in the transfer material can be used.
Further, the surface resistivity of the electroconductive layer in
the image-receiving material is preferably 10.sup.11
.OMEGA./.quadrature. or less. If the surface resistivity is more
than 10.sup.11 .OMEGA./.quadrature., charge that is charged by
corona discharge on the transfer material will hardly induce a
counter-charge on the electroconductive layer in the
image-receiving material, which is likely to result in a weakening
of adhesion by coulomb force between the transfer material and the
image-receiving material. The surface resistivity is preferably not
more than 10.sup.9 .OMEGA./.quadrature.. The thickness of the
electroconductive layer is preferably 0.01 to 2.0 .mu.m, and more
preferably 0.05 to 0.5 .mu.m. If this thickness is less than 0.01
.mu.m, the electrical conductance is likely to be insufficient,
while if this thickness is more than 2.0 .mu.m, the image-receiving
layer is likely to be colored by an electroconductive agent, thus
reducing commodity value. Thus, the above range is suitable.
[0142] The electroconductive layer is preferably earthed when
forming an image. If the electroconductive layer is not earthed,
charge on the transfer material will be unlikely to induce
counter-charge on the image-receiving material, thus reducing the
effect of the electroconductive layer.
[0143] A cushion layer may be provided between the support and the
image-receiving layer. If the cushion layer is provided, adhesion
between the coloring material layer and the image-receiving layer
can be improved during laser heat transfer, and quality of the
image can be improved. Further, even if foreign matter is mixed in
between the transfer material and the image-receiving sheet during
recording, gaps between the image-receiving layer and the coloring
material layer become small due to deformation action of the
cushion layer. As a result, the size of image defects such as
missing parts can also be reduced. Further, if the image formed by
transfer is transferred to separately prepared regular printing
paper or the like, the image-receiving surface is deformed,
depending on the unevenness of the paper, and thus transferability
of the image-receiving layer can be improved and glossiness of the
transferred material can be lowered, thereby improving the
similarity to printed matter.
[0144] The cushion layer is structured so as to be easily deformed
by application of stress to the image-receiving layer. To achieve
this effect, the cushion layer is preferably made of a material
with low elasticity, a material having rubber elasticity or a
thermoplastic resin that is easily softened by heating. The
elasticity of the cushion layer is preferably 9.8.times.10.sup.5 to
4.9.times.10.sup.7 Pa at room temperature, and particularly
preferably 2.9.times.10.sup.6 to 1.5.times.10.sup.7 Pa. For foreign
matter such as rubber to penetrate into the cushion layer, a degree
of penetration as stipulated under JIS K2530 (25.degree. C., 100 g,
5 seconds) is preferably 10 or more. The glass transition
temperature (Tg) of the cushion layer is 80.degree. C. or less, and
preferably 25.degree. C. or less. A plasticizer can be suitably
added to the polymer binder to regulate these physical properties,
such as Tg.
[0145] Specific materials that can be used as the binder in the
cushion layer include, in addition to rubbers such as urethane
rubber, butadiene rubber, nitrile rubber, acrylic rubber, natural
rubber and the like, polyethylene, polypropylene, polyester, a
styrene-butadiene copolymer, an ethylene-vinyl acetate copolymer,
an ethylene-acryl copolymer, a vinyl chloride-vinyl acetate
copolymer, vinylidene chloride resin, plasticizer-containing vinyl
chloride resin, polyamide resin, phenol resin and the like.
[0146] The thickness of the cushion layer depends on the resin used
and on other conditions, but is usually 3 to 100 .mu.m, preferably
10 to 52 .mu.m.
[0147] The image-receiving layer and the cushion layer should be
adhesive-bonded until the laser recording stage, but for transfer
of the image onto regular printing paper, these layers are
preferably arranged in a releasable manner. To facilitate release,
a release layer of 0.1 to 2 .mu.m in thickness is preferably
provided between the cushion layer and the image-receiving layer.
This release layer preferably functions as a barrier against a
coating solvent used for coating of the image-receiving layer.
[0148] The image-receiving sheet combined with said transfer
material maybe constituted such that the image-receiving layer also
serves as a cushion layer. In this case, the image-receiving sheet
may be composed of a support and a cushioning image-receiving layer
or of a support, an undercoat and a cushioning image-receiving
layer. In this case too, the cushioning image-receiving layer is
provided so as to be releasable, to enable re-transfer to regular
printing paper. In this case, the image after re-transfer to the
regular printing paper is an image excellent in glossiness.
[0149] The thickness of the cushioning image-receiving layer is 5
to 100 .mu.m, and preferably 10 to 40 .mu.m.
[0150] Further, for improvement of transferability of the
image-receiving sheet, it is preferable that the image-receiving
sheet is provided with a back layer at the opposite side of the
support to the side that is provided with the image-receiving
layer. To improve transportability in a recording device, it is
preferable to add to the back layer an antistatic agent (e.g. a
surfactant or fine particles of tin oxide) and a matting agent
(e.g. silicon oxide or PMMA particles).
[0151] The above additives can be added not only to the back layer
but also to the image-receiving layer and the other layers as
necessary. The types of the additives vary depending on intended
objectives and cannot be determined unconditionally. However, in
the case of, for example, the matting agent, particles of 0.5 to 10
.mu.m average particle diameter can be added in an amount of 0.5 to
80% to the layer. The antistatic agent can be suitably selected
from various surfactants and electroconductive agents and used such
that the surface resistivity of the layer is 10.sup.12
.OMEGA./.quadrature. or less, more preferably 10.sup.9
.OMEGA./.quadrature. or less, under conditions of 23.degree. C. and
50% RH.
[0152] Method of forming an image
[0153] Charging by corona discharge in the first aspect of the
present invention can be carried out using, for example, a corotron
charger using a wire, but is not particularly limited. Among corona
chargers, the corotron charger can charge the face of the coloring
material layer uniformly. Charging may be either positive or
negative, but positive charging can be used for more uniform
charging. A voltage of charging is suitably 5 to 6 kV, depending on
properties of the corotron wire.
[0154] The transfer material and the image-receiving material can
be utilized for forming an image as a laminate in which the
coloring material layer of the transfer material is laid on the
image-receiving layer of the image-receiving material.
[0155] The laminate consisting of the transfer material and the
image-receiving material can be formed by various methods. For
example, the laminate can be easily obtained by laying the coloring
material layer of the transfer material on the image receiving
layer of the image-receiving material and passing the resulting
laminate through pressing and heating rollers. A heating
temperature in this case is preferably 130.degree. C. or less, more
preferably 100.degree. C. or less, in the first aspect, and
preferably 160.degree. C. or less, more preferably 130.degree. C.,
in the second aspect.
[0156] As another method of obtaining the laminate, vacuum
adherence can also be preferably used. Vacuum adherence is a method
in which the image-receiving material is wound by suction at vacuum
pressure on a rotating drum having a vacuum forming mechanism
inside and provided thereon with a large number of fine gaps (i.e.
suction holes) for vacuum drawing, and then the transfer material,
which is slightly larger than the image-receiving material, is
vacuum-bonded to the image-receiving material under uniform
extrusion of air by squeeze rollers. As another method, there is
also a method in which the image-receiving material is stretched
and mechanically stuck to a metal drum, and then the transfer
material is mechanically stretched and stuck to the image-receiving
material. Among these methods, vacuum adherence is particularly
preferable in view of rapid and easy uniform lamination and
improvement of an effect for preventing missing portions, without
requiring regulation of the temperature of heat rollers or the
like.
[0157] Attachment of the transfer material to the image-receiving
material may be conducted just before the laser irradiation
operation.
[0158] In the image-forming method in the first aspect of the
invention, the transfer material 10 is charged. Thus, upon
lamination of the image-receiving material 20 and the transfer
material 10, wrinkles may occur. Accordingly, it is preferable that
the charged transfer material 10 is laid on the image-receiving
material 20 under strong tension.
[0159] In the laser light irradiation operation, the laser light is
scanned on the transfer material 10 side of the image-forming
laminate, usually reciprocating in the width direction of the
recording drum 40. During the laser light irradiation operation,
the recording drum 40 is rotated at a predetermined angular
velocity. Alternatively, recording may be conducted by scanning the
laser light over a plane from a laser light output head, without
using the recording drum 40 described above.
[0160] As the laser light, a direct laser light such as a gas laser
light (e.g. an argon ion laser light, helium-neon laser light,
helium-cadmium laser light or the like), a solid laser light (e.g.
a YAG laser light or the like,) or a semiconductor laser light,
colorant laser light, excimer laser light and the like can be
utilized. Further, such a laser light maybe passed through a
secondary harmonic element, and the light converted to half the
original wavelength can be used. In the image-forming method in the
present invention, the semiconductor laser is preferably used in
consideration of output power and easy modulation. Further, in the
image-forming method of the present invention, irradiation of the
laser light is conducted preferably under conditions where the beam
diameter at the light-heat exchange layer is in the range of 5 to
50 .mu.m (particularly 6 to 30 .mu.m), and the rate of scanning is
preferably not less than 1 m/sec. (particularly not less than 3
m/sec.).
[0161] In the multi-color image-forming method in the second aspect
of the invention, the laser light used in irradiation is
characterized by having the form of a multi-beam two-dimensional
array. The multi-beam two-dimensional array means that in recording
with laser irradiation, a plurality of laser beams is used. A spot
arrangement of these laser beams is a two-dimensional plane
arrangement consisting of a plurality of lines along a main
scanning direction and a plurality of lines along a subsidiary
scanning direction.
[0162] By use of laser light in a multi-beam two-dimensional array,
the time required for laser recording can be reduced.
[0163] The image-forming method in the first aspect of the
invention can be utilized in production of a black mask or in
formation of a monochromic image, and the method can also be
utilized advantageously in formation of a multi-color image.
[0164] In a method for forming a multi-color image, a large number
of image layers (coloring material layers having an image formed
thereon) on a plurality of transfer materials may be successively
overlaid on the same image-receiving material to form a multi-color
image, or images may be formed on image-receiving layers in a
plurality of image-receiving materials and then re-transferred to
regular printing paper or the like to form a multi-color image.
[0165] In the latter case, transfer materials having coloring
material layers containing coloring agents having mutually
different hues are prepared, and three or more independent
image-forming laminates (e.g., the four colors, cyan, magenta,
yellow and black) having a transfer material combined with an
image-receiving material are produced. Each of these laminates is
irradiated with laser light via, for example, a color separation
filter in accordance with digital signals based on an image. Next,
the transfer material is separated from the image-receiving
material to form an image of the respective color on each
image-receiving material. Then, the respective color images thus
formed are successively superposed on an actual support, such as
separately prepared regular printing paper or the like or on a
support similar thereto, whereby a multi-color image can be
formed.
EXAMPLES
[0166] Hereinafter, the present invention is described in more
detail by reference to Examples, which however are not intended to
limit the present invention. Unless otherwise specified, "parts"
means "parts by weight".
Example 1
Preparation of Transfer Material
[0167] 1) Formation of an electroconductive layer on a support
[0168] The respective components shown in the composition of a
coating solution described below were mixed during stirring by a
stirrer and then dispersed for 1 hour in a paint shaker (Toyo Seiki
Co., Ltd.) to prepare the coating solution for the
electroconductive layer.
[0169] Composition of the coating solution for the
electroconductive layer
3 Binder (RIKACOAT SN-20, produced by New Japan 200 parts Chemical
Co., Ltd.) N-Methyl-2-pyrrolidone 2000 parts Surfactant (Megafac
F-177, produced by Dainippon Ink and 0.5 parts Chemicals, Inc) Fine
tin oxide particles 1 100 parts
[0170] The tin oxide 1 in the composition was prepared by the
following method.
[0171] 80 parts of fine particles of a tin oxide-antimony oxide
complex described in the Examples in JP-A No. 61-20033, 160 parts
of N-methyl-2-pyrrolidone and 80 parts of zirconia beads of 1 mm in
diameter were introduced into a vessel of stainless steel and
dispersed for 6 hours in a paint shaker.
[0172] One side of the support (polyethylene terephthalate film of
A4 size with a thickness of 75 .mu.m) was coated with the above
coating solution for the electroconductive layer by a rotating
coater (Whirler), and this coated material was dried for 2 minutes
in an oven at 100.degree. C. to form an electroconductive layer
with a dry film thickness of 0.16 .mu.m.
[0173] The surface resistivity thereof, as determined at 25.degree.
C. in a 60% RH atmosphere, was 2.times.10.sup.7
.OMEGA./.quadrature..
[0174] 2) Formation of a light-heat exchange layer
[0175] The respective components shown in the composition of a
coating solution described below were mixed during stirring by a
stirrer and then dispersed for 1 hour in a paint shaker (Toyo Seiki
Co., Ltd.) to prepare the coating solution for the light-heat
exchange layer.
[0176] Composition of the coating solution for the light-heat
exchange layer
4 Light-heat exchange material (NK-2014, an infrared 10 parts
absorbing colorant, produced by Nippon Hasshoku Shikiso Co., Ltd.)
Binder (RIKACOAT SN-20, produced by New Japan 200 parts Chemical
Co., Ltd.) N-Methyl-2-pyrrolidone 2000 parts Surfactant (Megafac
F-177, Dainippon Ink and Chemicals, 1 part Inc)
[0177] The support on which the electroconductive layer was formed
in item 1) above was coated, at a side not provided with the
electroconductive layer, with the above coating solution for the
light-heat exchange layer by a rotating coater (Whirler), and this
coated material was dried for 2 minutes in an oven at 100.degree.
C. to form an intermediate layer having light-heat exchange ability
on the support.
[0178] The resulting light-heat exchange layer had an absorption
maximum in the wavelength range of 700 to 1000 nm in the vicinity
of 830 nm. Absorbance (optical density (OD)) was measured with a
Macbeth densitometer, which indicated an OD of 1.08.
[0179] 3) Formation of a yellow ink layer (coloring material
layer)
[0180] The respective components in the following composition of a
mother liquor having a pigment dispersed therein were dispersed for
2 hours in a paint shaker (Toyo Seiki Co., Ltd.), the glass beads
were removed, and the mother liquid having the yellow pigment
dispersed therein was thus prepared.
[0181] Composition of a mother liquid having a yellow pigment
dispersed therein
5 20 wt-% polyvinyl butyral solution 12 parts (DENKA BUTYRAL
#2000-L with a Vicat softening point of 57.degree. C., produced by
Denki Kagaku Kogyo K.K.) Coloring material (yellow pigment (C.I.
Pigment Yellow 24 parts 14)) Dispersant assistant 0.8 parts
(SOLSPERSE S-20000, produced by ICI) n-Propyl alcohol 110 parts
Glass beads 100 parts
[0182] The respective components shown in the composition of a
coating solution described below were mixed during stirring by a
stirrer to prepare a coating solution for a yellow ink layer.
[0183] Composition of the coating solution
6 The mother liquor having the yellow pigment dispersed 20 parts
therein n-Propyl alcohol 60 parts Surfactant 0.05 parts
[0184] (Megafac F-176PF, Dainippon Ink and Chemicals, Inc.)
[0185] The light-heat exchange layer formed in item 2) above was
coated for 1 minute with the above coating solution for the yellow
ink layer by a Whirler, and the coated material was dried for 2
minutes in an oven at 100.degree. C. to form the yellow ink layer
(64.2% by weight of the pigment, 33.7% by weight of polyvinyl
butyral) on the intermediate layer. This resulting ink layer was
measured for absorbance (optical density (OD)) with a Macbeth
densitometer, which indicated an OD of 0.7. The thickness of the
ink layer was measured in the same manner as for the intermediate
layer above, indicating a thickness of 0.4 .mu.m on average.
[0186] Thereafter, measurement of surface resistivity at ordinary
temperature and ordinary humidity indicated 1.2.times.10.sup.12
.OMEGA./.quadrature..
[0187] By the process described above, a transfer material having
an electroconductive layer on one side of a support and a
light-heat exchange layer and coloring material layer provided on
another side of the support was prepared.
[0188] Preparation of an image-receiving material
[0189] 1) Formation of an electroconductive layer
[0190] A coating solution used for the electroconductive layer was
the same as the coating solution used for formation of the
electroconductive layer in the transfer material, except that the
binder in the coating solution used for formation of the
electroconductive layer in the transfer material was replaced by a
vinyl chloride/vinyl acetate copolymer. One side of a support (a
polyethylene terephthalate sheet of A4 size with a thickness of 100
.mu.m) was coated with the coating solution in the same manner as
for formation of the electroconductive layer in the transfer
material, to form an electroconductive layer (film thickness, 0.15
.mu.m) of the image-receiving material. The surface resistivity of
the resulting electroconductive layer was 7.2.times.10.sup.7
.OMEGA./.quadrature..
[0191] 2) Formation of an image-receiving layer
[0192] {circle over (1)} Formation of a first image-receiving
layer
[0193] The respective components shown in the composition of a
coating solution described below were mixed during stirring by the
stirrer to prepare the coating solution for the first
image-receiving layer.
[0194] Composition of the coating solution for the first
image-receiving layer
7 Vinyl chloride/vinyl acetate copolymer (MPR-TSL, Nissin 25 parts
Chemical Industry Co., Ltd.) Dibutyloctyl phthalate (DOP, Daiachi
Kagaku Co., Ltd.) 12 parts Surfactant (Megafac F-177, Dainippon Ink
and Chemicals, 4 parts Inc) Solvent (methyl ethyl ketone) 75
parts
[0195] The surface of the electroconductive layer formed in item 1)
above was coated with the coating solution for the first
image-receiving layer by a Whirler, and the coated material was
dried for 2 minutes in an oven at 100.degree. C. to form the first
image-receiving layer (thickness, 20 .mu.m).
[0196] {circle over (2)} Formation of a second image-receiving
layer
[0197] The respective components shown in the composition of a
coating solution described below were mixed during stirring by a
stirrer to prepare the coating solution for the second
image-receiving layer.
[0198] Composition of the coating solution for the second
image-receiving layer
8 Polyvinyl butyral 16 parts (DENKA BUTYRAL #2000-L, Denki Kagaku
Kogyo K.K.) N,N-dimethylacrylamide/butyl acrylate copolymer 4 parts
Surfactant (Megafac F-177, Dainippon Ink and Chemicals, 0.5 parts
Inc) Solvent (n-propyl alcohol) 200 parts
[0199] The surface of the first image-receiving layer formed in
item {circle over (1)} above was coated with the coating solution
for the second image-receiving layer by a Whirler, and the coated
material was dried for 2 minutes in an oven at 100.degree. C. to
form the second image-receiving layer (thickness, 2 .mu.m)
[0200] By the process described above, an image-receiving material
having an electroconductive layer and two image-receiving layers
laminated on a support was prepared.
[0201] Formation of an image
[0202] Formation of an image was conducted using the image-forming
device shown in FIG. 1. Specifically, the image-receiving material
was fed to the surface of a recording drum provided with suction
holes (not shown) for vacuum adsorption, such that the
image-receiving layer was facing outward, and the image-receiving
material was joined to the surface of the drum by vacuum pressure.
The transfer material was fed to the image-receiving material such
that the coloring material layer was facing the image-receiving
layer of the image-receiving material. The face of the coloring
material layer in the transfer material was charged by corona
discharge with a corotron charger placed before the position where
the image-receiving material was brought into contact with the
transfer material. Charging voltage was 0.7 kV. The
electroconductive layer in the image receiving material and the
recording drum were earthed. The transfer material thus charged was
transferred to the recording drum and laid over the image-receiving
material. These laminated materials were irradiated with laser
light from a laser irradiation unit, not shown, to transfer the
coloring material layer to the image-receiving layer.
[0203] As the laser light, a semiconductor laser light with a
wavelength of 830 nm was condensed to form a spot with a diameter
of 7 .mu.m on the surface of the light-heat exchange layer and
moved (subsidiary scanning) in a direction perpendicular to a
rotating direction of the recording drum 14 (main scanning
direction), to conduct laser image recording on the laminate for
image formation. The laser irradiation conditions were as
follows:
[0204] Laser power: 110 mW
[0205] Main scanning rate: 4 m/sec.
[0206] Subsidiary scanning pitch (amount of subsidiary
scanning/rotation): 20 .mu.m
[0207] After the laser image recording described above had been
conducted, the laminate for image formation was removed from the
recording drum 14, and the image-receiving material 12 was peeled
from the transfer material 10 by hand, to form an image on the
image-receiving material 12.
[0208] The resulting image was of very good quality.
Example 2
Preparation of Transfer Material K (black)
[0209] 1) Preparation of a coating solution for a light-heat
exchange layer
[0210] The following respective components were mixed during
stirring in a stirrer to prepare a coating solution for a
light-heat exchange layer.
[0211] Composition of the coating solution of the light-heat
exchange layer
9 Infrared absorbing pigment 7.6 parts ("NK-2014", produced by
Nippon Kanko Shikiso Co., Ltd.) Polyimide resin 29.3 parts
("RIKACOAT SN-20" having a thermal decomposition temperature of
510.degree. C., produced by New Japan Chemical Co., Ltd.)
N,N-dimethylformamide 1500 parts Methyl ethyl ketone 360 parts
Surfactant 0.5 part ("Megafac F-177" , produced by Dainippon Ink
and Chemicals, Inc.) Matting agent 1.7 parts ("SEAHOSTAR KEP150":
silica gel particles, produced by Nippon Shokubai Co.. Ltd.)
[0212] 2) Formation of the light-heat exchange layer on the surface
of a support
[0213] One surface (central line average roughness, 0.04 .mu.m) of
a polyethylene terephthalate film (support) of 75 .mu.m thickness
was coated with the above coating solution for the light-heat
exchange layer by a rotating applicator (Whirler), and the coated
material was dried for 2 minutes in an oven at 120.degree. C. to
form the light-heat exchange layer on the support. The resulting
light-heat exchange layer showed absorption at a wavelength in the
vicinity of 830 nm, and absorbance (optical density (OD)) was
measured by a UV-visible spectrophotometer UV-2400 (Shimadzu
Corporation), which indicated an OD of 0.9. The thickness of the
light-heat exchange layer was 0.3 .mu.m on average, as determined
by observation of a section thereof under a scanning electron
microscope.
[0214] 3) Preparation of a coating solution for a black coloring
material layer
[0215] The following respective components were introduced into a
kneader mill and preliminarily dispersed by application of shearing
force while a small amount of solvent was added thereto. A solvent
was added to the resulting dispersion to finally prepare the
following composition, which was then dispersed for 2 hours in a
sand mill to provide a mother liquor having a pigment dispersed
therein.
[0216] Composition of the mother liquor having a black pigment
dispersed therein
10 Polyvinyl butyral 12.6 parts ("ESRECK B BL-SH", produced bu
Sekisui Chemical Co., Pigment 10.5 parts Ltd.) (Carbon black
"MA-100" with a PVC blackness of 10, pro- duced by Mitsubishi
Chemical Industries Ltd.) Pigment 4.5 parts (CVarbon black "#5"
with a PVC blackness of 1, produced by Mitsubishi Chemical
Industries Ltd.) Dispersant assistant 0.8 parts ("SOLSPERSE
S-20000", produced by ICI) n-Propyl alcohol 79.4 parts
[0217] Then, the following respective components were mixed in a
stirrer to prepare a coating solution for the black coloring
material layer.
[0218] Composition of a coating solution for the black coloring
material layer
11 The mother liquor having the black pigment dispersed 185.7 parts
therein Polyvinyl butyral 11.9 parts ("ESRECK B BL-SH", produced by
Sekisui Chemical Co., Ltd.) Wax compounds (Stearic amide "NEWTRON
2", produced by Nippon Fine Chemical 1.7 parts Co., Ltd.) (Behenic
amide "DIAMID BM", produced by Nippon Kasei Chemical 1.7 parts Co.,
Ltd.) (Lauric amide "DIAMID Y", produced by Nippon Kasei Chemical
Co., 1.7 parts Ltd.) (Palmitic amide "DIAMID KP", produced by
Nippon Kasei Chemical 1.7 parts Co., Ltd.) (Erucic amide "DIAMID
L-200", produced by Nippon Kasei Chemical 1.7 parts Co., Ltd.)
(Oleic amide "DIAMID O-200", produced by Nippon Kasei Chemical 1.7
parts Co., Ltd.) Rosin 11.4 parts ("KE-311", produced by Arakawa
Kagaku Co., Ltd.) Surfactant 2.1 parts ("Megafac F-176P" with a
solid content of 20%, produced by Dainippon Ink and Chemicals,
Inc.) Inorganic pigment 7.1 parts ("MEK-ST", 30% methyl ethyl
ketone solution, produced by Nissan Kagaku Co., Ltd.) n-Propyl
alcohol 1050 parts Methyl ethyl ketone 295 parts
[0219] Particles in the resulting coating solution for the black
coloring material layer were measured by a particle
distribution-measuring device with a laser scattering system, which
indicated that the average particle diameter was 0.25 .mu.m and a
proportion of particles of 1 .mu.m or more was 0.5%.
[0220] 4) Formation of the black coloring material layer on the
surface of the light-heat exchange layer
[0221] The surface of the light-heat exchange layer was coated for
1 minute with the above coating solution for the black coloring
material layer, and the coated material was dried for 2 minutes in
an oven at 100.degree. C., to form the black coloring material
layer on the light-heat exchange layer. A transfer material K
having the light-heat exchange layer and the black coloring
material layer provided in that order on the support was prepared
by the process described above.
[0222] The optical density (OD) of the black coloring material
layer in the transfer material K was measured by a Macbeth
densitometer "TD-904" (W filter), which indicated an OD of 0.91.
The thickness of the black coloring material layer was determined
to be 0.60 .mu.m on average.
Preparation of Transfer Material Y (yellow)
[0223] A transfer material Y was prepared in the same manner as for
preparation of the above transfer material K except that a coating
solution for a yellow coloring material layer with the following
composition was used in place of the coating solution for the black
coloring material layer. The thickness of the coloring material
layer in the resulting transfer material Y was 0.42 .mu.m.
[0224] Composition of a mother liquor having a yellow pigment
dispersed therein
12 Polyvinyl butyral 7.1 parts ("ESRECK B BL-SH", produced by
Sekisui Chemical Co., Ltd.) Pigment 12.9 parts (Yellow pigment (P.
Y. 139)) Dispersant assistant 0.6 parts ("SOLSPERSE S-20000",
produced by ICI) n-Propyl alcohol 79.4 parts
[0225] Composition of a coating solution for a yellow coloring
material layer
13 The mother liquor having the yellow pigment dispersed 126 parts
therein Polyvinyl butyral 4.6 parts ("ESRECK B BL-SH", produced by
Sekisui Chemical Co., Ltd.) Wax compounds (Stearic amide "NEWTRON
2", produced by Nippon Fine Chemical 0.7 parts Co., Ltd.) (Behenic
amide "DIAMID BM", produced by Nippon Kasei Chemical 0.7 parts Co.,
Ltd.) (Lauric amide "DIAMID Y", produced by Nippon Kasei Chemical
Co., 0.7 parts Ltd.) (Palmitic amide "DIAMID KP", produced by
Nippon Kasei Chemical 0.7 parts Co., Ltd.) (Erucic amide "DIAMID
L-200", produced by Nippon Kasei Chemical 0.7 parts Co., Ltd.)
(Oleic amide "DIAMID O-200", produced by Nippon Kasei Chemical 0.7
parts Co., Ltd.) Nonionic surfactant 0.4 parts ("CHEMISTAT 1100",
produced by Sanyo Chemical Industries, Ltd.) Rosin 2.4 parts
("KE-311", produced by Arakawa Kagaku Co., Ltd.) Surfactant 0.8
parts ("Megafac F-176P" with a solid content of 20 %, produced by
Dainippon Ink and Chemicals, Inc.) n-Propyl alcohol 793 parts
Methyl ethyl ketone 198 parts
Preparation of Transfer Material M (magenta)
[0226] A transfer material M was prepared in the same manner as for
preparation of the above transfer material K except that a coating
solution for a magenta coloring material layer with the following
composition was used in place of the coating solution for the black
coloring material layer. The thickness of the coloring material
layer in the resulting transfer material M was 0.38 .mu.m.
[0227] Composition of a mother liquor having a magenta pigment
dispersed therein
14 Polyvinyl butyral 12.6 parts ("DENKA BUTYRAL #2000-L"with a
Vicat softening point of 57.degree. C., produced by Denki Kagaku
Kogyo K.K.) Pigment 15.0 parts (Magenta pigment "Shimura Brilliant
Carmine 6B-229", produced by Dainippon Ink and Chemicals, Inc.)
Dispersion assistant 0.6 parts ("SOLSPERSE S-20000", produced by
ICI) n-Propyl alcohol 79.4 parts Composition of a coating solution
for the magenta coloring material layer The mother liquor having
the magenta pigment dispersed 163 parts therein Polyvinyl butyral
4.0 parts ("DENKA BUTYRAL #2000-L" with a Vicat softening point of
57.degree. C., produced by Denki Kagaku Kogyo K.K.) Wax compounds
(Stearic amide "NEWTRON 2", produced by Nippon Fine Chemical 1.0
part Co., Ltd.) (Behenic amide "DIAMID BM", produced by Nippon
Kasei Chemical 1.0 part Co., Ltd.) (Lauric amide "DIAMID Y",
produced by Nippon Kasei Chemical Co., 1.0 part Ltd.) (Palmitic
amide "DIAMID KP", produced by Nippon Kasei Chemical 1.0 part Co.,
Ltd.) (Erucic amide "DIAMID L-200", produced by Nippon Kasei
Chemical 1.0 part Co., Ltd.) (Oleic amide "DIAMID O-200", produced
by Nippon Kasei Chemical 1.0 part Co., Ltd.) Nonionic surfactant
0.7 parts ("CHEMISTAT 1100", produced by Sanyo Chemical Industries,
Ltd.) Rosin 4.6 parts ("KE-311", produced by Arakawa Kagaku Co.,
Ltd.) Monomer 2.5 parts ("PET-4A", produced by Shin Nakamura Kagaku
Co., Ltd.) Surfactant 1.3 parts ("Megafac F-176P" with a solid
content of 20%, produced by Dainippon Ink and Chemicals, Inc.)
n-Propyl alcohol 848 parts Methyl ethyl ketone 246 parts
Preparation of Transfer Material C (cyan)
[0228] A transfer material C was prepared in the same manner as for
preparation of the above transfer material K except that a coating
solution for a cyan coloring material layer with the following
composition was used in place of the coating solution for the black
coloring material layer. The thickness of the coloring material
layer in the resulting transfer material C was 0.45 .mu.m.
[0229] Composition of a mother liquor having a cyan pigment
dispersed therein
15 Polyvinyl butyral 12.6 parts ("ESRECK B BL-SH", produced by
Sekisui Chemical Co., Ltd.) Pigment 15.0 parts (Cyan pigment
(Pigment Blue 15, "#700-10 FG CY-Blue")) Dispersion assistant 0.8
parts ("PW-36", produced by Kusumoto Kasei Co., Ltd.) n-Propyl
alcohol 110 parts Composition of a coating solution off the cyan
coloring material layer The mother liquor having the cyan pigment
dispersed therein 118 parts Polyvinyl butyral 5.2 parts ("ESRECK B
BL-SH", produced by Sekisui Chemical Co., Ltd.) Wax compounds
(Stearic amide "NEWTRON 2", produced by Nippon Seika Co., 1.0 part
Ltd.) (Behenic amide "DIAMID BM", produced by Nippon Kasei Chemical
1.0 part Co., Ltd.) (Lauricamide "DIAMID Y", produced by Nippon
Kasei Chemical Co., 1.0 part Ltd.) (Palmitic amide "DIAMID KP",
produced by Nippon Kasei Chemical 1.0 part Co., Ltd.) (Erucic amide
"DIAMID L-200", produced by Nippon Kasei Chemical 1.0 part Co.,
Ltd.) (Oleic amide "DIAMID O-200", produced by Nippon Kasei
Chemical 1.0 part Co., Ltd.) Rosin 2.8 parts ("KE-311", produced by
Arakawa Kagaku Co., Ltd.) Monomer 1.7 parts ("PET-4A", produced by
Shin Nakamura Kagaku Co., Ltd.) Surfactant 1.7 parts ("Megafac
F-176P" with a solid content of 20%, produced by Dainippon Ink and
Chemicals, Inc.) n-Propyl alcohol 890 parts Methyl ethyl ketone 247
parts
Preparation of an Image-receiving Sheet
[0230] A coating solution for a cushion immediate layer and a
coating solution for an image-receiving layer, having the following
compositions, were prepared.
[0231] 1) Coating solution for the cushion intermediate layer
16 Vinyl chloride/vinyl acetate copolymer 20 parts (MPR-TSL,
produced by Nissin Chemical Industry Co., Ltd.) Plasticizer 10
parts ("PARAPLEX G-40", produced by CP. HALL. COMPANY) Surfactant
(Megafac F-177, produced by Dainippon Ink and 0.5 parts Chemicals,
Inc.) Antistatic agent 0.3 parts ("SAT-S Supper (IC)", Nippon
Junyaku Co., Ltd.) 60 parts Methyl ethyl ketone Toluene 10 parts
N,N-dimethylformamide 3 parts 2) Coating solution for the
image-receiving layer Polyvinyl butyral 8 parts ("ESRECK B BL-SH",
produced by Sekisui Chemical Co., Ltd.) Antistatic agent 0.7 part
("SUNSTAT 2012A", produced by Sanyo Chemical Industries, Ltd.)
Surfactant 0.1 part ("Megafac F-177", produced by Dainippon Ink and
Chemicals, Inc.) n-Propyl alcohol 20 parts Methanol 20 parts
1-Methoxy-2-propanol 50 parts
[0232] Using a small-width coating machine, the above coating
solution for the cushion intermediate layer was coated onto a white
PET support ("LUMILAR E-68L" with a thickness of 135 .mu.m,
produced by Toray Co., Ltd.), this coated layer was dried, and the
coating solution for the image-receiving layer was coated thereon
and dried. The amounts of the coating solutions were regulated such
that the thickness of the cushion intermediate layer after drying
was about 20 .mu.m, and the thickness of the image-receiving layer
was about 2 .mu.m. The prepared material was wound into a roll,
stored at room temperature for 1 week and used for image recording
with laser light as described below.
Formation of a Transferred Image
[0233] The image-receiving sheet (25 cm.times.35 cm) prepared above
was wound and vacuum-adsorbed onto a rotating drum 25 cm in
diameter provided with vacuum section holes 1 mm in diameter
(surface density: 1 hole for an area of 3 cm.times.8 cm). Then, the
transfer material K (black), cut to 30 cm.times.40 cm, and was laid
thereover, so as to stick out uniformly from the image-receiving
sheet. While being squeezed by squeeze rollers, the transfer
material was joined and laminated by air-suction from the section
holes. A degree of reduced pressure with the section holes thus
covered was -150 mmHg relative to 1 atmosphere. The drum was
rotated. A semiconductor laser light with a wavelength of 830 nm
was condensed to form a spot with a diameter of 7 .mu.m on the
surface of the light-heat exchange layer in the laminate on the
drum, and then moved (subsidiary scanning) in a direction
perpendicular to the rotation direction (main scanning direction)
of the recording drum, thus recording a laser image (image line) on
the laminate. The laser irradiation conditions were as follows. The
laser beam used in this example made use of a laser beam consisting
of a multi-beam two-dimensional array forming a parallelogram of 5
rows of beams in the main scanning direction and 3 rows of beams in
the subsidiary scanning direction.
[0234] Laser power: 110 mW
[0235] Main scanning rate: 6 m/sec.
[0236] Subsidiary scanning pitch: 6.35 .mu.m
[0237] Environmental temperature and humidity: 3 conditions:
18.degree. C. and 30%, 23.degree. C. and 50%, 26.degree. C. and
65%.
[0238] After the laser image recording described above had
finished, the laminate was removed from the drum. When the transfer
material K was peeled from the image-receiving sheet by hand, it
was confirmed that only an irradiated region of the coloring
material layer in the transfer material K had transferred from the
transfer material K to the image-receiving sheet.
[0239] In the same manner as above, an image was transferred from
each of the transfer material Y, the transfer material M, and the
transfer material C to the image-receiving sheet. When the four
transferred color images were further laid over and transferred
onto recording paper to form a multi-color image, a high-quality
multi-color image with stable transfer density could be formed,
even with laser recording with high energy laser light in a
multi-beam two-dimensional array under different temperatures and
humidities.
[0240] Measurement of reflection density (OD) of a black image
portion and calculation of rate of image transfer
[0241] The density of the transferred image obtained using the
above transfer material K (black) under the respective temperature
and humidity conditions was measured with a reflective Macbeth
densitometer "RD-918" (W filter). The reflection density (OD) was
obtained as shown in Table 1 below.
[0242] The above transfer material K was transferred to a
image-receiving sheet using a thermal laminator, without laser
recording. Reflection density (OD) of a resulting black image, as
determined by the method described above, was 1.88. Rates of
transfer of the image by laser recording were 98.4%, 96.8% and
96.3%, respectively.
[0243] Evaluation of quality of the black image
[0244] A solid portion and a line image portion of the transferred
images obtained using the above transfer material K (black) under
the respective temperature and humidity conditions were observed
under an optical microscope. A black transferred image having no
gaps in the solid portion and a good resolution of the line image,
with little dependence on environmental conditions, had been
obtained. Evaluation of image qualities was conducted by visual
examination using the following criteria:
Solid Portion
[0245] .largecircle.: Recording gaps and transfer defects were not
present.
[0246] .DELTA.: Recording gaps and transfer defects were partially
present.
[0247] X: Recording gaps and transfer defects were present over the
whole surface.
Line Image Portion
[0248] .largecircle.: The edge of the line image portion was sharp
with good resolving power.
[0249] .DELTA.: The edge of the line image portion was not smooth,
and bridging occurred in parts.
[0250] X: Bridging occurred over the whole surface.
Example 3
[0251] A multi-color image was formed in the same manner as in
Example 2 except that the following transfer material (K-2) was
used in place of the transfer material K, and as a result, a
high-quality multi-color image with stable transfer density could
be formed, even by laser recording with high energy laser light in
a multi-beam two-dimensional array under different temperatures and
humidities.
[0252] The transfer material (K-2) was prepared in the same manner
as in Example 2 except that carbon black "#5" used for preparation
of the coating solution for the black coloring material layer in
the transfer material K was replaced by carbon black "MA-100".
(thickness of the coloring material layer: 0.59 .mu.m)
[0253] The resulting transfer material (K-2) was used, reflection
density (OD) of a black image portion was measured, the transfer
rate of the image was calculated, and the quality of the black
image was evaluated (solid density with the thermal laminator:
2.01), in the same manner as in Example 2. The evaluation results
are shown in Table 1 below.
Example 4
[0254] A multi-color image was formed in the same manner as in
Example 2 except that the following transfer material (K-3) was
used in place of the transfer material K, and as a result, a
high-quality multi-color image with stable transfer density could
be formed, even by laser recording with high energy laser light in
a multi-beam two-dimensional array under different temperatures and
humidities.
[0255] The transfer material (K-3) was prepared in the same manner
as in Example 2 except that carbon black "MA-100" used for
preparation of the coating solution for the black coloring material
layer in the transfer material K was replaced by carbon black "#5".
(thickness of the coloring material layer: 0.62 .mu.m)
[0256] The resulting transfer material (K-3) was used, reflection
density (OD) of a black image portion was measured, the transfer
rate of the image was calculated, and the quality of the black
image was evaluated (solid density with the thermal laminator:
1.79), in the same manner as in Example 2. The evaluation results
are shown in Table 1 below.
Example 5
[0257] A multi-color image was formed in the same manner as in
Example 2 except that the following transfer material (K-4) was
used in place of the transfer material K, and as a result, a
high-quality multi-color image with stable transfer density could
be formed, even by laser recording with high energy laser light in
a multi-beam two-dimensional array under different temperatures and
humidities.
[0258] The transfer material (K-4) was prepared in the same manner
as in Example 2 except that carbon black "#5" used for preparation
of the coating solution for the black coloring material layer in
the transfer material K was replaced by carbon black "#20" (PVC
blackness of 4, produced by Mitsubishi Chemical Industries Ltd.).
(thickness of the coloring material layer: 0.60 .mu.m)
[0259] The resulting transfer material (K-4) was used, reflection
density (OD) of a black image portion was measured, the transfer
rate of the image was calculated, and the quality of the black
image was evaluated (solid density with the thermal laminator:
1.92), in the same manner as in Example 2. The evaluation results
are shown in Table 1 below.
Comparative Example 1
[0260] A multi-color image was formed in the same manner as in
Example 2 except that the following transfer material (K-5) was
used in place of the transfer material K, and as a result, solid
image density was significantly reduced when laser recording was
conducted under higher humidity conditions.
[0261] The transfer material (K-5) was prepared in the same manner
as in Example 2 except that the thickness of the black coloring
material layer in the transfer material K was changed from 0.60
.mu.m to 0.45 .mu.m.
[0262] The resulting transfer material (K-5) was used, reflection
density (OD) of a black image portion was measured, the transfer
rate of the image was calculated, and the quality of the black
image was evaluated (solid density with the thermal laminator:
1.41), in the same manner as in Example 2. The evaluation results
are shown in Table 1 below.
Comparative Example 2
[0263] A multi-color image was formed in the same manner as in
Example 2 except that the following transfer material (K-6) was
used in place of the transfer material K, and as a result, gaps
were observed in a solid portion under conditions of 18.degree. C.
and 30% RH. Further, the resolving power of a line image portion
was deteriorated.
[0264] The transfer material (K-6) was prepared in the same manner
as in Example 1 except that the thickness of the black coloring
material layer in the transfer material K was changed from 0.60
.mu.m to 0.75 .mu.m.
[0265] The resulting transfer material (K-6) was used, reflection
density (OD) of a black image portion was measured, the transfer
rate of the image was calculated, and the quality of the black
image was evaluated (solid density with the thermal laminator:
2.26), in the same manner as in Example 2. The evaluation results
are shown in Table 1 below.
Comparative Example 3
[0266] A multi-color image was formed in the same manner as in
Comparative Example 1 except that a single laser beam was used in
place of the multi-beam two-dimensional array. As a result, the
reduction of density in a solid portion that occurred in
Comparative Example 1 did not occur.
[0267] Using the transfer material (K-5) obtained in Comparative
Example 1, reflection density (OD) of a black image portion was
measured in the same manner as in Comparative Example 1 except that
the single laser beam was used in place of the multi-beam
two-dimensional array, the transfer rate of the image was
calculated, and the quality of the black image was evaluated (solid
density with the thermal laminator: 1.41). The evaluation results
are shown in Table 1 below.
17 TABLE 1 Image quality temperature Reflection Transfer Line image
and humidity density (OD) Rate (%) Solid portion portion Example 2
18.degree. C., 30% RH 1.85 98.4 .largecircle. .largecircle.
23.degree. C., 50% RH 1.82 96.8 .largecircle. .largecircle.
26.degree. C., 65% RH 1.81 96.3 .largecircle. .largecircle. Example
3 18.degree. C., 30% RH 1.94 96.5 .largecircle. .largecircle.
23.degree. C., 50% RH 1.91 95.0 .largecircle. .largecircle.
26.degree. C., 65% RH 1.89 94.0 .largecircle. .largecircle. Example
4 18.degree. C., 30% RH 1.75 97.8 .largecircle. .largecircle.
23.degree. C., 50% RH 1.74 97.2 .largecircle. .largecircle.
26.degree. C., 65% RH 1.70 95.0 .largecircle. .largecircle. Example
5 18.degree. C., 30% RH 1.88 97.9 .largecircle. .largecircle.
23.degree. C., 50% RH 1.86 96.9 .largecircle. .largecircle.
26.degree. C., 65% RH 1.84 95.8 .largecircle. .largecircle.
Comparative 18.degree. C., 30% RH 1.31 92.9 .largecircle.
.largecircle. Example 1 23.degree. C., 50% RH 1.24 87.9 .DELTA.
.largecircle. 26.degree. C., 65% RH 1.06 75.2 X .largecircle.
Comparative 18.degree. C., 30% RH 2.10 92.9 X X Example 2
23.degree. C., 50% RH 2.25 99.6 .largecircle. .DELTA. 26.degree.
C., 65% RH 2.24 99.1 .largecircle. X Comparative 18.degree. C., 30%
RH 1.38 97.9 .largecircle. .largecircle. Example 3 23.degree. C.,
50% RH 1.35 95.7 .largecircle. .largecircle. 26.degree. C., 65% RH
1.33 94.3 .largecircle. .largecircle. N.B.: The laser recording in
Comparative Example 3 took a long time.
[0268] From the results in Table 1, it is understood that the black
transfer materials used in the multi-color image-forming method of
the present invention in Examples 2 to 5 have excellent image
quality even under different temperature and humidity
conditions.
[0269] In the black transfer material used in the multi-color
image-forming method in Comparative Example 1, on the other hand,
the transfer rate in the solid portion was significantly reduced
under highly humid conditions. Further, in the black transfer
material used in the multi-color image-forming method in
Comparative Example 2, gaps resulting from insufficient transfer
occurred in the solid portion under low humidity conditions, and
the resolving power of the line-image portion was significantly
worsened. Further, in Comparative Example 3, where a single laser
beam was used in place of the multi-beam two-dimensional array, the
reduced rate of transfer in the solid portion that occurred in
Comparative Example 1 did not occur, but the time required for
laser recording was longer.
* * * * *