U.S. patent application number 11/672206 was filed with the patent office on 2007-06-14 for photosensitive lithographic printing plate and method for making a printing plate.
This patent application is currently assigned to LASTRA S.p.A.. Invention is credited to Kazuhiro Kohori, Hideaki Okamoto, Toshiyuki Urano.
Application Number | 20070134592 11/672206 |
Document ID | / |
Family ID | 27566968 |
Filed Date | 2007-06-14 |
United States Patent
Application |
20070134592 |
Kind Code |
A1 |
Urano; Toshiyuki ; et
al. |
June 14, 2007 |
PHOTOSENSITIVE LITHOGRAPHIC PRINTING PLATE AND METHOD FOR MAKING A
PRINTING PLATE
Abstract
A photosensitive lithographic printing plate includes a
photosensitive layer and a protective layer formed in this order on
a support, wherein the photosensitive layer has a maximum peak of
spectral sensitivity within a wavelength range ranging from 390 to
430 nm, the minimum exposure for the photosensitive lithographic
printing plate for image formation at a wavelength of 410 nm (S410)
is at most 100 .mu.J/cm.sup.2, and the relation between the minimum
exposure for image formation at a wavelength of 450 nm (S450) and
the minimum exposure for image formation at a wavelength of 410 nm
(S410) is 0<S410/S450.ltoreq.0.1.
Inventors: |
Urano; Toshiyuki; (Aoba-ku,
Yokohama-shi, JP) ; Kohori; Kazuhiro; (Aoba-ku,
Yokohama-shi, JP) ; Okamoto; Hideaki; (Aoba-ku,
Yokohama-shi, JP) |
Correspondence
Address: |
AGFA;c/o KEATING & BENNETT, LLP
8180 GREENSBORO DRIVE
SUITE 850
MCLEAN
VA
22102
US
|
Assignee: |
LASTRA S.p.A.
Via Brescia, 36
Manerbio (Brescia)
IT
25025
|
Family ID: |
27566968 |
Appl. No.: |
11/672206 |
Filed: |
February 7, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11299792 |
Dec 13, 2005 |
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11672206 |
Feb 7, 2007 |
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10737804 |
Dec 18, 2003 |
7041431 |
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11299792 |
Dec 13, 2005 |
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09837655 |
Apr 19, 2001 |
6689537 |
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10737804 |
Dec 18, 2003 |
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Current U.S.
Class: |
430/270.1 |
Current CPC
Class: |
G03F 7/033 20130101;
Y10S 430/146 20130101; Y10S 430/148 20130101; G03F 7/027 20130101;
G03F 7/2055 20130101; G03F 7/029 20130101; G03F 7/0388 20130101;
G03F 7/031 20130101 |
Class at
Publication: |
430/270.1 |
International
Class: |
G03C 1/00 20060101
G03C001/00 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 19, 2000 |
JP |
2000-117803 |
May 1, 2000 |
JP |
2000-131995 |
May 1, 2000 |
JP |
2000-131996 |
Nov 30, 2000 |
JP |
2000-364310 |
Dec 4, 2000 |
JP |
2000-368412 |
Dec 5, 2000 |
JP |
2000-369415 |
Jan 25, 2001 |
JP |
2001-016537 |
Claims
1. A photosensitive lithographic printing plate precursor
comprising: a support; and a photosensitive layer; wherein said
photosensitive layer contains (A) an ethylenic monomer, (B) a
sensitizing agent, and (C) a radical generator; and said
sensitizing agent is a dialkylaminobenzene compound including an
aromatic heterocyclic group as a substituent on the carbon atom at
the p-position relative to the amino group on the benzene ring.
2. The photosensitive lithographic printing plate precursor of
claim 1, wherein said radical generator (C) comprises a
hexaarylbiimidazole compound or a titanocene compound.
3. The photosensitive lithographic printing plate precursor of
claim 2, wherein said hexaarylbiimidazole compound is present in an
amount ranging from 15 to 40 parts by weight based on 100 parts by
weight of said ethylenic monomer.
4. The photosensitive lithographic printing plate precursor of
claim 2, wherein said titanocene compound is present in an amount
ranging from 5 to 20 parts by weight based on 100 parts by weight
of said ethylenic monomer.
5. The photosensitive lithographic printing plate precursor of
claim 1, wherein said photosensitive layer comprises a coloring
pigment in an amount from 0 to 20 wt. % based on the weight of said
photosensitive layer.
6. The photosensitive lithographic printing plate precursor of
claim 1, wherein said photosensitive layer further comprises a
polymer binder.
7. The photosensitive lithographic printing plate according to
claim 6, wherein the polymer binder contains a structural unit
represented by the following formula (V): ##STR16## wherein Re is a
hydrogen atom or a methyl group.
8. The photosensitive lithographic printing plate precursor of
claim 1, wherein said photosensitive layer further comprises a
hydrogen-donor compound.
9. The photosensitive lithographic printing plate precursor of
claim 8, wherein said hydrogen-donor compound comprises a mercapto
group.
10. The photosensitive lithographic printing plate precursor of
claim 1, wherein said photosensitive layer further comprises an
amine compound having a pKb of at most 7 at 25.degree. C.
11. The photosensitive lithographic printing plate precursor of
claim 1, wherein said photosensitive layer further comprises an
amine compound having a group of the formula [N--CH2].
12. The photosensitive lithographic printing plate precursor of
claim 1, wherein said photosensitive layer comprises, as the
ethylenic monomer, a urethane compound (a3) having at least four
urethane linkages and at least four addition-polymerizable double
bonds in one molecule.
13. The photosensitive lithographic printing plate precursor of
claim 12, wherein said urethane compound (a3) has a molecular
weight ranging from 600 to 200,000.
14. The photosensitive lithographic printing plate precursor of
claim 12, wherein said urethane compound (a3) is represented by
formula (II): ##STR17## wherein x is an integer ranging from 4 to
20, y is an integer ranging from 0 to 15, z is an integer ranging
from 1 to 15, Ra is a group having a repeating unit derived from
alkyleneoxy or aryleneoxy, and having from 4 to 20 oxy groups
capable of combining with Rb, each of Rb and Rc, which are
independent of each other, is a C.sub.1-10 alkylene group, and Rd
is an organic residue having from 1 to 10 (meth)acrylic group,
provided that each of Ra, Rb, Rc and Rd which are independent of
one another, may have a substituent.
15. The photosensitive lithographic printing plate precursor of
claim 12, wherein said urethane compound (a3) as the ethylenic
monomer (A), is prepared by reacting a compound having at least
four active isocyanate groups in one molecule (a1) with a compound
having at least one hydroxyl group and at least two
addition-polymerizable double bonds in one molecule (a2).
16. The photosensitive lithographic printing plate precursor of
claim 15, wherein the compound (a1) having at least four active
isocyanate groups in one molecule has a molecular weight of at
least 500.
17. The photosensitive lithographic printing plate precursor of
claim 1, wherein said photosensitive layer comprises, as the
ethylenic monomer (A), a phosphate compound having an acryloyloxy
group or a methacryloyloxy group.
18. The photosensitive lithographic printing plate precursor of
claim 1, wherein said photosensitive layer further comprises a
surface active agent.
19. The photosensitive lithographic printing plate precursor of
claim 1, further comprising a protective layer including polyvinyl
alcohol.
20. The photosensitive lithographic printing plate precursor of
claim 1, further comprising a protective layer including polyvinyl
pyrrolidone.
21. The photosensitive lithographic printing plate precursor of
claim 1, wherein said support includes aluminum or an aluminum
alloy having a roughened surface, and said support has a reflection
density of at least 0.3.
22. The photosensitive lithographic printing plate precursor of
claim 1, wherein said support includes aluminum or an aluminum
alloy having a roughened surface and an anodized layer.
23. A method for making a printing plate, which comprises:
image-wise exposing the photosensitive lithographic printing plate
precursor as defined in claim 1 with laser light having a
wavelength ranging from about 390 nm to about 430 nm; and
developing the exposed plate with an aqueous developer.
24. The method for making a printing plate according to claim 23,
wherein an exposure energy of the printing plate precursor in the
image-wise exposing step at a wavelength of 410 nm is at most 100
.mu.J/cm.sup.2.
25. The method for making a printing plate according to claim 23,
wherein an exposure energy of the printing plate precursor in the
image-wise exposing step at a wavelength of 410 nm is at most 50
.mu.J/cm.sup.2.
25. The method for making a printing plate according to claim 23,
wherein a relation between a minimum exposure energy for image
formation of the printing plate precursor at a wavelength of 450 nm
(S450) and a minimum exposure energy for image formation of the
precursor at a wavelength of 410 nm (S410) is
0<S410/S450.ltoreq.0.1.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a photosensitive
lithographic printing plate which is sensitive to a laser light
having a wavelength ranging from 390 to 430 nm and which is
suitable for direct drawing from digital signals of e.g. computers,
and a method for making a printing plate.
[0003] 2. Description of the Related Art
[0004] Heretofore, a lithography method has been widely used for
the microfabrication of e.g. lithographic printing plates, printed
boards, color filters, large scale integrated circuits (LSI), thin
film transistors (TFT), liquid crystal displays (LCD), plasma
display panels (PDP) and semiconductor packagings (TAB), wherein an
image forming material having a layer of a photosensitive
composition formed on the surface of a support is image-exposed
through a mask, to form a pattern which utilizes the difference in
solubility of a developer between exposed portions and non-exposed
portions of the photosensitive layer.
[0005] For example, a photopolymerization initiation system for the
resist material for color filters, is a combination of a
hexaarylbiimidazole derivative with an aminobenzophenone derivative
as taught, for example, in JP-A-11-327127.
[0006] However, the resist material for color filters disclosed in
JP-A-11-327127 is not intended to be exposed to laser light ranging
from 390 to 430 nm, but rather is subjected through a mask to the
light from the like of a high-pressure mercury-vapor lamp. Further,
since the material contains a large amount of a pigment, a large
quantity of energy of 200 mJ/cm.sup.2, for example, is required for
image formation.
[0007] Further, U.S. Pat. No. 5,863,678 discloses a resist material
for color filters containing a titanocene compound and a
dialkylaminobenzene compound as a photopolymerization initiation
system. The above patent discloses various kinds of light sources.
However, the resist material is also exposed to light through a
mask from a high pressure mercury vapor lamp source, practically,
and the exposure energy of the light is high, for example 70
mJ/cm.sup.2 or more.
[0008] Further, the above patent does not disclose safe light
properties under a yellow lamp for a photosensitive lithographic
printing plate.
[0009] On the other hand, the laser direct drawing method has
attracted attention in recent years directly forming an image from
digital information supplied by a computer, without using a mask,
by employing a laser light as a light source for exposure, since
improvement in not only productivity but resolution and accuracy of
position and the like. Accordingly, the utilization of a laser
light in the lithography method has been actively studied.
[0010] With respect to the laser light, various light sources
emitting light from the ultraviolet to infrared region are known.
Potential laser light for use in image exposure, is light in the
visible to infrared region emitted by devices, such as an argon ion
laser, a helium-neon laser, a YAG laser and a semiconductor laser.
These devices are mentioned from the viewpoint of output,
stability, photoperceptivity, cost and the like. For example,
various photosensitive compositions have been proposed for use with
an argon ion laser having a wavelength of 488 nm and a FD-YAG laser
having a wavelength of 532 nm, and a photosensitive lithographic
printing plate for exposure to light from these lasers has been
placed into practical use. Examples of such photosensitive
compositions are a combination of a titanocene compound with a
bipyromethene complex and a combination of titanocene with a
coumarin derivative as described, for example, in
JP-A-11-271969.
[0011] However, no conventional compositions are known which are
responsive upon exposure to a violaceous laser light having a
wavelength of from 390 to 430 nm.
[0012] Further, in an image formation method utilizing such visible
laser light, a photosensitive composition showing an adequate
absorption at the visible region is used. However, the sensitivity
of the composition to violaceous laser light having a wavelength
ranging from 390 to 430 nm tends to be inadequate, and safe light
properties under a yellow lamp (under environment containing a
light having a wavelength of from about 500 to about 750 nm) tend
to be poor in some cases, and accordingly the operation has to be
conducted in a dark room environment using a red lamp.
[0013] On the other hand, JP-A-61-117549 discloses, as a
photosensitive lithographic printing plate which has excellent in
safe light properties, a photosensitive lithographic printing plate
having a protective layer containing a specific coloring agent
formed on a photopolymerizable photosensitive composition layer. It
discloses as an exposure source, general-purpose light sources such
as high-pressure mercury-vapor lamps and metal halide lamps, and
argon ion lasers, helium-cadmium lasers and krypton lasers as well,
and it discloses as a polymerization initiator a complex system of
biimidazole and Michler's ketone. However, JP-A-61-117549,
specifically discloses that a composition having a relative
sensitivity to light of a wavelength at 480 nm when exposed to a
xenon lamp, and a composition responsive to radiation energies
required for image formation at 488 nm using an argon ion laser and
a composition responsive to light of 442 nm the case of using a
helium-cadmium laser, attracted attention. The publication
discloses that no attention has been paid to compositions
responsive to laser light having an oscillation wavelength of from
390 to 430 nm, particularly from 400 to 420 nm. It also discloses
that a composition responsive to radiation energy required for
image formation of 0.6 to 1.0 mJ/cm.sup.2 to light from a
helium-cadmium laser having a wavelength of 442 nm is not yet
sufficient.
[0014] On the contrary, along with significant progress in laser
technology in recent years, a laser emitting light in the
ultraviolet region, which can operate in a bright room environment
such as under a yellow lamp, particularly a semiconductor laser
which can stably oscillate in a wavelength region of from 390 to
430 nm, particularly from 400 to 420 nm, has been developed.
However, no photosensitive lithographic printing plate suitable for
exposure to laser within the violaceous light region (light ranging
from 390 to 430 nm in wavelength) has yet been found.
SUMMARY OF THE INVENTION
[0015] Accordingly, one object of the present invention to provide
a highly sensitive photosensitive lithographic printing plate which
is responsive to violaceous laser light.
[0016] Another object of the present invention is to provide a
method for making a printing plate using the photosensitive
lithographic printing plate.
[0017] Briefly, these objects and other objects of the present
invention as hereinafter will become more readily apparent can be
attained by a photosensitive lithographic printing plate comprising
a photosensitive layer and a protective layer formed in this order
on a support, wherein the photosensitive layer has a maximum peak
of spectral sensitivity within a wavelength range ranging from 390
to 430 nm, the minimum exposure for the photosensitive lithographic
printing plate for image formation at a wavelength of 410 nm (S410)
is at most 100 .mu.J/cm.sup.2, and the relation between the minimum
exposure for image formation at a wavelength of 450 nm (S450) and
the minimum exposure for image formation at a wavelength of 410 nm
(S410) is 0<S410/S450.ltoreq.0.1.
[0018] A second aspect of the present invention is a photosensitive
lithographic printing plate comprising a photosensitive layer and a
protective layer formed in this order on a support, the
photosensitive layer containing (A) an ethylenic monomer, (B) a
sensitizing pigment and (C) a radical generator, wherein the
radical generator (C) contains a hexaarylbiimidazole compound or a
titanocene compound, and the sensitizing agent (B) contains a
dialkylaminobenzene compound.
[0019] A third aspect of the present invention is a method for
making a printing plate, which comprises image-exposing the
photosensitive lithographic printing plate according to the first
or second aspect of the present invention, by means of a laser
light having a wavelength of from 390 to 430 nm, followed by
development of the image by an aqueous developer.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0020] In the first aspect of the present invention, the
photosensitive lithographic printing plate comprises a
photosensitive layer and a protective layer formed in this order on
a support, the photosensitive layer having a maximum peak of
spectral sensitivity within a wavelength range ranging from 390 to
430 nm, the minimum exposure for image formation at a wavelength of
410 nm being at most 100 .mu.J/cm.sup.2, and the ratio of the
minimum exposure for image formation at a wavelength of 410 nm
(S410) to the minimum exposure for image formation at a wavelength
of 450 nm (S450), i.e. S410/S450 being at most 0.1.
[0021] The maximum peak of spectral sensitivity is more preferably
within a wavelength range ranging from 400 to 420 nm. If the
maximum peak of spectral sensitivity for a photosensitive
composition is in a wavelength region less than the above range,
the sensitivity to a laser light having a wavelength ranging from
390 to 430 nm (hereinafter sometimes referred to as a laser light
in the violaceous region) tends to be poor. On the contrary, if the
maximum peak of spectral sensitivity is in a wavelength region
exceeding the above range, the sensitivity to laser light in the
violaceous region may be high, but the safe light properties of the
composition under a yellow lamp tend to be poor.
[0022] The minimum exposure for image formation of a composition at
a wavelength of 410 nm is at most 100 .mu.J/cm.sup.2, preferably at
most 50 .mu.J/cm.sup.2, more preferably at most 35 .mu.J/cm.sup.2.
If the minimum exposure is more than 100 .mu.J/cm.sup.2, the
exposure time tends to be long, such being impractical, although
that depends on the exposure intensity of the laser light
source.
[0023] Here, the lower the lower limit, the better, but it is
usually at least 1 .mu.J/cm.sup.2, and it is at least 2.5
.mu.J/cm.sup.2 practically.
[0024] In the present invention, the "maximum peak of spectral
sensitivity" of a composition may, for example, be determined by a
method disclosed in e.g. "Photopolymer Technology" (Tsugio Yamaoka,
Nikkan Kogyo Shinbunsha, 1988, page 262) as follows. Samples of a
photosensitive image-forming material having a layer consisting of
a photosensitive composition (a photosensitive layer) formed on the
surface of a support, are irradiated with light emitted from a
light source such as a xenon lamp or a tungsten lamp for exposure,
using a spectral sensitivity measuring apparatus (Here, the samples
are irradiated so that the exposure wavelength linearly decreases
in the horizontal axis direction, and the exposure intensity
logarithmically decreases in the vertical axis direction.),
followed by developing the samples to obtain a resist image
depending upon each exposure wavelength, whereupon the exposure
energy required for image formation is calculated from the height
of the image. The exposure wavelength showing the maximum peak in a
spectral sensitivity curve obtained by plotting the wavelength on
the horizontal axis and the inverse of the above exposure energy on
the vertical axis, corresponds to the maximum peak of spectral
sensitivity.
[0025] Further, the minimum exposure for image formation at a
wavelength of 410 nm is determined as an exposure energy calculated
from the height of the image obtained in the same manner as
described above using a spectral sensitivity measuring
apparatus.
[0026] Here, the minimum exposure for image formation is the
minimum exposure required to form an image when the photosensitive
layer is exposed and developed under optimum development conditions
determined by changing, e.g., the developer, such as by changing
the pH of the developer, the development temperature or the
development time depending upon the type of photosensitive
composition used. The minimum exposure is usually the minimum
exposure required to form an image by soaking the photosensitive
layer in an alkali developer having a pH ranging from 11 to 14 at
25.degree. C. for from 30 seconds to 3 minutes after exposure.
[0027] Further, with respect to the photosensitive lithographic
printing plate of the present invention, the ratio of the minimum
exposure for image formation at a wavelength of 410 nm (S410:
J/cm.sup.2) to the minimum exposure for image formation at a
wavelength of 450 nm (S450: J/cm.sup.2) i.e. S410/S450 is at most
0.1. The value of S410/S450 is preferably at most 0.05. That is,
when the minimum exposure S450 for image formation at a wavelength
of 450 nm is large and the minimum exposure S410 for image
formation at a wavelength of 410 nm is small, handling efficiency
of the composition tends to be excellent in an environment in which
the light has a wavelength in the vicinity of 500 nm, i.e. under a
yellow lamp, and accordingly the smaller the above ratio, the
better. Here, the minimum of S410/S450 is 0, which indicates that
S450 is infinitely large. That is, the photosensitive layer is
completely insensitive to a light having a wavelength of 450
nm.
[0028] Further, from the viewpoint of handling efficiency under a
yellow lamp, the minimum exposure for image formation at a
wavelength longer than 450 nm is preferably larger than the minimum
exposure for image formation at a wavelength of 450 nm.
Specifically, the minimum exposure for image formation at each of
wavelength exceeding 450 nm and at most 750 nm is preferably larger
than the minimum exposure for image formation at a wavelength of
450 nm (S450). It is particularly preferred that the maximum peak
of spectral sensitivity within a wavelength range ranging from 390
to 430 nm of the photosensitive layer is the maximum peak of
spectral sensitivity within a wavelength range ranging from 390 to
750 nm.
[0029] The above photosensitive lithographic printing plate is
particularly useful when exposed to laser light having an
oscillation wavelength of from 400 to 420 nm.
[0030] The constituency of the photosensitive layer in the
photosensitive lithographic printing plate is not particularly
limited so long as it satisfies the above definition. However,
preferably a photopolymerizable composition is used which contains
an ethylenic compound and a photopolymerization initiation system
(a combination of a sensitizing agent with a radical generator),
which has an advantage over a silver salt type photosensitive
composition in view of handling efficiency in waste disposal after
development or the like.
[0031] The photosensitive lithographic printing plate of the second
aspect of the present invention is explained below. The
photosensitive lithographic printing plate is a photosensitive
lithographic printing plate containing specific constituents to
achieve the physical properties of the photosensitive layer of the
photosensitive lithographic printing plate of the first aspect of
the present invention.
Ethylenic Monomer
[0032] In the present invention, the ethylenic monomer (A) is a
compound having a radically-polymerizable ethylenic double bond
which undergoes addition polymerization by the action of a
photopolymerization initiation system, when the photosensitive
composition is irradiated with active light radiation, and which
undergoes crosslinking and curing in some cases. It may be a
compound having one ethylenic double bond in a molecule, and
specifically, it may, for example, be an unsaturated carboxylic
acid such as acrylic acid, methacrylic acid (hereinafter
(meth)acrylic), crotonic acid, isocrotonic acid, maleic acid,
itaconic acid or citraconic acid, an alkyl ester thereof,
(meth)acrylonitrile, (meth)acrylamide or styrene. However,
preferred is a compound having at least two ethylenic double bonds
in a molecule from the viewpoint of polymerizability, crosslinking
properties and the resulting increase in difference in solubility
in a developer of the exposed portions and non-exposed portions of
a photosensitive composition.
[0033] Suitable ethylenic monomers include (A-1) an ester of an
unsaturated carboxylic acid with an aliphatic polyhydroxyl
compound, (A-2) a phosphate containing an acryloyloxy group or a
methacryloyloxy group, (A-3) a urethane(meth)acrylate or (A-4) an
epoxy (meth)acrylate.
[0034] The ester of an unsaturated carboxylic acid with an
aliphatic polyhydroxyl compound (A-1) may be an ester of the
above-mentioned unsaturated carboxylic acid with an aliphatic
polyhydroxyl compound such as ethylene glycol, diethylene glycol,
triethylene glycol, tetraethylene glycol, propylene glycol,
trimethylene glycol, 1,3-butanediol, tetramethylene glycol,
neopentyl glycol, hexamethylene glycol, trimethylolethane,
trimethylolpropane, glycerol, pentaerythritol, dipentaerythritol or
sorbitol. Specific examples of the ester include ethylene glycol
di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene
glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate,
propylene glycol di(meth)acrylate, 1,3-butanediol di(meth)acrylate,
tetramethylene glycol di(meth)acrylate, neopentyl glycol
di(meth)acrylate, hexamethylene glycol di(meth)acrylate,
trimethylolethane tri(meth)acrylate, tetramethylolethane
tri(meth)acrylate, trimethylolpropane tri(meth)acrylate, glycerol
di(meth)acrylate, glycerol tri(meth)acrylate, pentaerythritol
di(meth)acrylate, pentaerythritol tri(meth)acrylate,
pentaerythritol tetra(meth)acrylate, dipentaerythritol
di(meth)acrylate, dipentaerythritol tetra(meth)acrylate,
dipentaerythritol penta(meth)acrylate, dipentaerythritol
hexa(meth)acrylate, sorbitol tri(meth)acrylate, sorbitol
tetra(meth)acrylate, sorbitol penta(meth)acrylate and sorbitol
hexa(meth)acrylate, and similar crotonates, isocrotonates,
maleates, itaconates and citraconates.
[0035] The phosphate containing an acryloyloxy group or a
methacryloyloxy group (A-2) embodiment is not particularly limited
so long as it is a phosphate compound having a (meth)acryloyloxy
group in its structure. Particularly preferred phosphates are those
represented by the following formulas (Ia) or and (Ib): ##STR1##
wherein R.sup.1 is a hydrogen atom or a methyl group, n is an
integer ranging from 1 to 25, and m is 1, 2 or 3.
[0036] Here, n preferably ranges from 1 to 10, particularly
preferably from 1 to 4, and specific examples include
methacryloyloxy ethyl phosphate, bis(methacryloyloxy
ethyl)phosphate and methacryloyloxy ethylene glycol phosphate.
These compounds may be used alone or as a mixture.
[0037] The urethane (meth)acrylate (A-3) may, for example, be a
urethane(meth)acrylate of a polyisocyanate compound such as an
aliphatic polyisocyanate such as hexamethylene diisocyanate or
trimethylhexamethylene diisocyanate, an alicyclic polyisocyanate
such as cyclohexane diisocyanate or isophorone diisocyanate or an
aromatic polyisocyanate such as tolylene diisocyanate, xylylene
diisocyanate or diphenylmethane diisocyanate, with an unsaturated
hydroxyl compound such as hydroxymethyl(meth)acrylate,
hydroxyethyl(meth)acrylate, glycerol di(meth)acrylate,
pentaerythritol tri(meth)acrylate or tetramethylolethane
tri(meth)acrylate. Specifically, hexamethylene
bis[(meth)acryloyloxy methylurethane], hexamethylene
bis[(meth)acryloyloxy ethylurethane], hexamethylene
bis{tris[(meth)acryloyloxymethyl]methylurethane} or hexamethylene
bis{tris[(meth)acryloyloxymethyl]ethylurethane} may, for example,
be mentioned.
[0038] The epoxy (meth)acrylate (A-4) may, for example, be an
epoxy(meth)acrylate of a polyepoxy compound such as (poly)ethylene
glycol polyglycidyl ether, (poly)propylene glycol polyglycidyl
ether, (poly)tetramethylene glycol polyglycidyl ether,
(poly)pentamethylene glycol polyglycidyl ether, (poly)neopentyl
glycol polyglycidyl ether, (poly)hexamethylene glycol polyglycidyl
ether, (poly)trimethylolpropane polyglycidyl ether, (poly)glycerol
polyglycidyl ether or (poly)sorbitol polyglycidyl ether, with a
hydroxy(meth)acrylate compound such as hydroxymethyl(meth)acrylate
or hydroxyethyl(meth)acrylate.
[0039] Further, another ethylenic monomer may, for example, be an
ester of an unsaturated carboxylic acid with an aromatic
polyhydroxyl compound such as hydroquinone di(meth)acrylate,
resorcin di(meth)acrylate or pyrogallol tri(meth)acrylate, a
(meth)acrylhydroxyl compound such as a (meth)acryloyl ethylene
oxide addition product of ethylene glycol or a (meth)acryloyl
diethylene oxide addition product of
2,2-bis(4-hydroxyphenyl)propane, or a condensate of a polyhydroxyl
compound, an unsaturated carboxylic acid and a polyhydric
carboxylic acid, such as a condensate of ethylene glycol,
(meth)acrylic acid and phthalic acid, a condensate of diethylene
glycol, (meth)acrylic acid and maleic acid, a condensate of
pentaerythritol, (meth)acrylic acid and terephthalic acid, or a
condensate of butanediol, glycerol, (meth)acrylic acid and adipic
acid. Further, an amide of the above-mentioned unsaturated
carboxylic acid with an aliphatic polyamine compound such as
methylene diamine, ethylene diamine, diethylene triamine or
hexamethylene diamine, specifically, methylene bis(meth)acrylamide,
ethylene bis(meth)acrylamide, diethylene triamine
tris(meth)acrylamide or hexamethylene bis(meth)acrylamide may, for
example, be mentioned.
[0040] A preferred ethylenic monomers is a (meth)acryloyloxy
group-containing phosphate, and the content of the
(meth)acryloyloxy group-containing phosphate in the photosensitive
composition preferably ranges from 1 to 60 wt %, particularly
preferably from 2 to 40 wt %, based on the entire ethylenic monomer
content of the photosensitive layer. Within this range, exposure
sensitivity and printing resistance of the photosensitive layer
tend to improve, and developing properties of the composition tend
to improve (stain at a non-image portion will decrease).
[0041] Another preferred ethylenic monomer is urethane
(meth)acrylates, and among the urethane (meth)acrylates, a urethane
compound (a3) having at least four urethane linkages
[--NH--(C.dbd.O)--O--] and at least four addition-polymerizable
double bonds in one molecule is preferred. The method of producing
the urethane compound is not particularly limited, but preferably a
compound (a1) having at least four active isocyanate groups in one
molecule is reacted with a compound (a2) having at least one
hydroxyl group and at least two addition-polymerizable double bonds
in one molecule, since a urethane linkage can easily be formed by
the addition reaction of an isocyanate group (--N.dbd.C.dbd.O) with
a hydroxyl group.
[0042] As to the question of why a composition exhibits improved
sensitivity by the addition of the urethane type compound (a3) to a
composition, the following may be considered. For example, the
formation of active urethane radicals, because of a chain transfer
reaction or photopolymerization of multi-functional acrylate groups
in the urethane type compound (a3), induces a high photo-setting
action, and this photo-setting action is increased by the high
molecular weight of the urethane compound (a3).
[0043] Compound (a1) having at least four active isocyanate groups
in one molecule may, for example, be a compound having at least
four active isocyanate groups in the molecule which are introduced
by the reaction of a compound having at least two alcoholic
hydroxyl groups (hereinafter referred to as polyhydric alcohol)
with a compound having at least two isocyanate groups. Specific
examples of compound (al) are prepared by reacting a compound
having at least four alcoholic hydroxyl groups in one molecule such
as pentaerythritol or polyglycerol with a diisocyanate compound
such as hexamethylene diisocyanate, toluene diisocyanate,
isophorone diisocyanate or trimethyl hexamethylene diisocyanate; or
a compound prepared by reacting a compound containing at least two
alcoholic hydroxyl groups in one molecule such as ethylene glycol
with a compound containing at least three isocyanate groups in one
molecule such as a biuret compound including Duranate 24A-100,
22A-75PX, 21S-75E and 18H-70B manufactured by Asahi Chemical
Industry Co., Ltd. or an adduct compound including P-301-75E,
E-402-90T and E-405-80T manufactured by Asahi Chemical Industry
Co., Ltd.
[0044] Further, a compound having at least four isocyanate groups
on the average in one molecule may be prepared by
homopolymerization of an isocyanate of ethylmethacrylate or by
copolymerization of the compound with another component. Specific
examples of the compound (a1) having at least four isocyanate
groups in one molecule include Duranate ME20-100 (trade name,
manufactured by Asahi Chemical Industry Co., Ltd.)
[0045] The number of isocyanate groups in compound (a1) is
preferably at least 6, particularly preferably at least 7. If the
number of isocyanate groups is less than 4, the sensitivity of the
resulting composition tends to be poor. The upper limit of
isocyanate groups is not particularly limited, but if the number is
too high, synthesis tends to be difficult, and accordingly the
number of isocyanate units is preferably at most 20. The number of
the isocyanate groups may be adjusted by the number of hydroxyl
groups in the polyhydric alcohol, the type of compound having at
least two isocyanate groups and the blending ratio.
[0046] The molecular weight of compound (a1) is usually at least
500, preferably at least 1,000, and at most 200,000, preferably at
most 150,000. If the molecular weight is beyond this range,
sensitivity of the photosensitive composition tends to
decrease.
[0047] Compound (a2) having at least one hydroxyl group and at
least two addition-polymerizable double bonds in one molecule,
constituting urethane compound (a3), may, for example, be a
compound having at least one alcoholic hydroxyl group, prepared by
esterification of a compound having a plurality of alcoholic
hydroxyl groups such as a polyhydric alcohol with a compound
containing a carboxyl group and a (meth)acryloyl group, i.e. a
reaction product prepared by reacting the above carboxyl
group-containing compound in such a proportion that at least one
alcoholic hydroxyl group remains. More specifically, compound (a2)
may be a hydroxyl group-containing multi-functional acrylate
compound having at least one alcoholic hydroxyl group, which is an
ester of a polyhydric alcohol with acrylic acid, such as a compound
prepared by reaction of 3 mols of acrylic acid with 1 mol of
pentaerythritol, a compound prepared by reaction of 2 mols of
acrylic acid with 1 mol of pentaerythritol, a compound prepared by
reaction of 5 mols of acrylic acid with 1 mol of dipentaerythritol,
or a compound prepared by reaction of 4 mols of acrylic acid with 1
mol of dipentaerythritol, and specific examples include
pentaerythritol triacrylate, pentaerythritol diacrylate,
dipentaerythritol diacrylate, dipentaerythritol triacrylate,
dipentaerythritol tetraacrylate and dipentaerythritol
pentaacrylate. Such a compound may be used alone or as a mixture in
a photosensitive composition.
[0048] Other examples of compound (a2) include the reaction product
of a compound containing an epoxy group such as glycidyl methyl
ether with a compound having at least one carboxyl group and at
least one addition-polymerizable double bond; a reaction product of
a compound having at least one epoxy group and at least one
addition-polymerizable double bond with a compound containing at
least one carboxyl group; and a reaction product of a compound
having at least one carboxyl group and at least one
addition-polymerizable double bond with a compound having at least
one epoxy group and at least one addition-polymerizable double
bond. An example of such a reaction product is the reaction product
of glycidyl methacrylate with (meth)acrylic acid. Preferred
compounds (a2) are those which have at least three
addition-polymerizable double bonds, in view of the sensitivity of
product photosensitive compositions.
[0049] The reaction of compound (a1) with compound (a2), i.e. the
reaction of the isocyanate group in compound (a1) with the hydroxyl
group in compound (a2), to prepare the urethane compound (a3), may
be conducted in accordance with a known method. Specifically, the
isocyanate group in compound (a1) and the hydroxyl group in
compound (a2) are reacted in a proportion of 1/10 to 10. For
example, both compounds can be dissolved in an organic solvent such
as toluene or ethyl acetate, followed by heating the solution at a
temperature ranging from 10 to 150.degree. C. for 5 minutes to 30
hours. Another suitable method requires the addition of a catalyst
such as n-butyl tin dilaurate in a required amount to a solution of
the reactants. Still another method is to first dilute compound
(a2) in a proper organic solvent and then dropwise add compound
(a1) thereto. Yet another satisfactory method is the reverse
[0050] The molecular weight of urethane compound (a3) is preferably
at least 600. If it is at most 600, the layer consisting of the
photosensitive composition (non-cured film) tends to exhibit poor
fastness. On the other hand, the upper limit is not particularly
limited, but it is preferably at most 150,000 in view of ease of
synthesis and availability. The molecular weight may be adjusted on
the basis of the types of compounds (a1) and (a2) and the degree of
esterification.
[0051] Urethane compound (a3) has at least four
addition-polymerizable double bonds in view of the desired
sensitivity of the product photosensitive composition, but it has
more preferably at least six, particularly preferably at least
eight, double bonds.
[0052] The urethane type compound (a3) may be used alone or as a
mixture. Particularly when the material of the urethane compound is
a mixture, the urethane compound (a3) is used as a mixture of
reaction products.
[0053] In the production of urethane compound (a3), a functional
group other than the addition-polymerizable double bond may be
introduced into the molecule for the purpose of controlling various
properties of the photosensitive composition. For example, a
compound (a4) having a hydroxyl group and a carboxyl group in one
molecule in combination with compound (a2) may be reacted with
compound (a1) to prepare a compound having at least four urethane
linkages, at least four addition-polymerizable double bonds and a
carboxyl group in one molecule.
[0054] More specifically, a compound (a1') having at least four
isocyanate groups in one molecule, a compound (a2') having one
hydroxyl group and two addition-polymerizable double bonds in one
molecule and a compound (a4') having one hydroxyl group and one
carboxyl group in one molecule may be reacted at a molar ratio of
a1':a2':a4' of 1:3:1 to produce a compound (a3') having four
urethane linkages, and six double bonds and one carboxyl group on
the average, in one molecule.
[0055] As the compound (a4) for reaction with compound (a1) in
combination with compound (a2) (the compound having a hydroxyl
group and a carboxyl group in one molecule), specifically, an
aliphatic carboxylic acid having a hydroxyl group, such as
2-hydroxyoctanic acid, 2-hydroxyhexanoic acid, 2-hydroxydecanoic
acid, 3-hydroxyoctanoic acid or 8-hydroxyoctanoic acid, is
preferred, and a C.sub.4-20 carboxylic acid having a hydroxyl group
at the a-position of the carboxylic acid is particularly preferred.
As the urethane compound (a3), preferred is a urethane compound
represented by the following formula (II): ##STR2## wherein x is an
integer ranging from 4 to 20, y is an integer ranging from 0 to 15,
z is an integer ranging from 1 to 15, Ra is a group having a
repeating unit derived from alkyleneoxy or aryleneoxy, and having
from 4 to 20 oxy groups which are capable of combining with Rb,
each of Rb and Rc which are independent of each other, is a
C.sub.1-10 alkylene group, and Rd is an organic residue having from
one to ten (meth)acrylic group, provided that each of Ra, Rb, Rc
and Rd which are independent of one another, may have a
substituent.
[0056] The alkyleneoxy group which is present in the repeating unit
in Ra, may be an alkyleneoxy residue of, e.g. glycerol,
pentaerythritol or propylene triol, and the aryleneoxy group which
is present in the repeating unit in Ra, may be a phenoxy residue
of, e.g. pyrogallol or 1,3,5-benzene triol.
[0057] It is preferred that x be an integer ranging from 4 to 15, y
be an integer ranging from 1 to 10, z be an integer ranging from 1
to 10, each of Ra and Rc which are independent of each other, is a
C.sub.1-5 alkylene group, and Rd is an organic residue having from
one to seven (meth)acrylic groups.
[0058] More preferably, Ra is ##STR3## wherein k is from 2 to 10,
each of Rb and Rc, which are independent of each other, is
--C.sub.2H.sub.4--, --CH.sub.2--C(CH.sub.3)-- or
--C.sub.3H.sub.6--, and Rd is ##STR4## The compounding ratio of
urethane compound (a3) ranges from 0.5 to 50 parts by weight,
preferably from 1 to 40 parts by weight, more preferably from 2 to
30 parts by weight, based on 100 parts by weight of the ethylenic
monomer. Photopolymerization Initiation System
[0059] The photopolymerization initiation system usually contains a
radical generator (C) and a sensitizing agent (B) and further
contains a hydrogen-donor compound as a polymerization accelerator
as the case requires. The radical generator (C) is a compound which
receives light excitation energy from the sensitizing agent (B)
when the sensitizing agent is irradiated with active light
radiation, generates active radicals by the absorbed energy, and
causes the above ethylenic monomer to undergo polymerization. The
components of the photosensitive layer of the photosensitive
lithographic printing plate of the second aspect of the present
invention comprise a hexaarylbiimidazole compound or a titanocene
compound as the radical generator (C), and a dialkylaminobenzene
compound as the sensitizing agent (B).
[0060] The hexaarylbiimidazole compound may be a dimer of an
imidazole compound having three aryl groups which generates
radicals directly by exposure to a laser ranging in wavelength from
390 to 430 nm or by interaction with the copresent sensitizing
agent. The hexaarylbiimidazole compound may, for example, be a
hexaarylbiimidazole compound as disclosed in, e.g. JP-B-45-37377,
JP-A-47-2528 or JP-A-54-15529, and specifically, it may, for
example, be 2,2'-bis(o-chlorophenyl)-4,4',5,5'-tetraphenyl
biimidazole,
2,2'-bis(o-chlorophenyl)-4,4',5,5'-tetra(p-methoxyphenyl)biimidazole,
2,2'-bis(o-chlorophenyl)-4,4',5,5'-tetra(p-methylphenyl)biimidazole,
2,2'-bis(o-chlorophenyl)-4,4',5,5'-tetra(p-ethoxycarbonylphenyl)biimidazo-
le,
2,2'-bis(o-chlorophenyl)-4,4',5,5'-tetra(p-fluorophenyl)biimidazole,
2,2'-bis(o-bromophenyl)-4,4',5,5'-tetra(p-iodophenyl)biimidazole,
2,2'-bis(o-chlorophenyl)-4,4',5,5'-tetra(p-chloronaphthyl)biimidazole,
2,2'-bis(o-chlorophenyl)-4,4',5,5'-tetra(p-chlorophenyl)biimidazole,
2,2'-bis(o-bromophenyl)-4,4',5,5'-tetra(p-chlor-p-methoxyphenyl)biimidazo-
le,
2,2'-bis(o-chlorophenyl)-4,4',5,5'-tetra(o,p-dichlorophenyl)biimidazol-
e,
2,2'-bis(o-chlorophenyl)-4,4',5,5'-tetra(o,p-dibromophenyl)biimidazole,
2,2'-bis(o-bromophenyl)-4,4',5,5'-tetra(o,p-dichlorophenyl)biimidazole,
or
2,2'-bis(o,p-dichlorophenyl)-4,4',5,5'-tetra(o,p-dichlorophenyl)biimid-
azole. Of these compounds, preferred is a hexaphenylbiimidazole
compound. A particularly preferred hexaphenylbiimidazole compound
is one which has the ortho-positions of the benzene rings at the
2,2'-positions on the imidazole rings substituted by halogen, and
still more preferred is one which in addition has the benzene rings
at the 4,4',5,5'-positions on the imidazole rings not substituted,
substituted by halogen or substituted by alkoxycarbonyl.
[0061] Such a hexaarylbiimidazole may be used in combination with
various biimidazoles as the case requires. The biimidazoles can
easily be synthesized by the method disclosed in Bull. Chem. Soc.
Japan. 33,565 (1960) or J. Org. Chem. 36[16]2262 (1971).
[0062] Suitable titanocene compounds include titanium compounds
having a dicyclopentadienyl structure and a biphenyl structure,
such as dicyclopentadienyl titanium dichloride, dicyclopentadienyl
titanium bisphenyl, dicyclopentadienyltitanium
bis(2,4-difluorophenyl), dicyclopentadienyl titanium
bis(2,6-difluorophenyl), dicyclopentadienyl titanium
bis(2,4,6-trifluorophenyl), dicyclopentadienyl titanium
bis(2,3,5,6-tetrafluorophenyl), dicyclopentadienyl titanium
bis(2,3,4,5,6-pentafluorophenyl), di(methylcyclopentadienyl)
titanium bis(2,6-difluorophenyl), di(methylcyclopentadienyl)
titanium bis(2,3,4,5,6-pentafluorophenyl) or dicyclopentadienyl
titanium bis[2,6-difluoro-3-(1-pyrrolyl)phenyl], may, for example,
be mentioned, and a preferred compound is one having the
o-positions of the biphenyl ring replaced with a halogen atom.
[0063] Further, it is possible to use, as a radical generator, the
above hexaarylbiimidazole compound and the titanocene compound in
combination.
[0064] The dialkylaminobenzene type compound which is used as the
sensitizing agent (B) may have any optional substituent so long as
it is a compound which has a dialkylaminobenzene structure, absorbs
light having a wavelength ranging from 390 to 430 nm, and
efficiently generates radicals from the radical generator by
interaction with the radical generator. Preferred is a
dialkylaminobenzophenone compound, a dialkylaminobenzene compound
having an aromatic heterocyclic group as a substituent on the
carbon atom at the p-position relative to the amino group on the
benzene ring, or a compound having a nitrogen-containing
heterocyclic structure formed by linkage of the alkyl groups
constituting the dialkylamino group in said compound and/or by
linkage of said alkyl group with the carbon atom on the benzene
ring adjacent to the carbon atom to which the amino group is
bonded. Here, the amino groups constituting the dialkylamino group
may be the same or different, and have a carbon number preferably
ranging from 1 to 6.
[0065] Of these compounds, particularly preferred are
dialkylaminobenzene compounds represented by the following formulae
(IIIa) and (IIIb): ##STR5## wherein each of R.sup.2 to R.sup.5,
which are independent of one another, is a C.sub.1-6 alkyl group,
and each of R.sup.6 to R.sup.9 is a hydrogen atom or a C.sub.1-6
alkyl group, provided that R.sup.2 and R.sup.3, R.sup.4 and
R.sup.5, R.sup.2 and R.sup.6, R.sup.3 and R.sup.7, R.sup.4 and
R.sup.8, or R.sup.5 and R.sup.9, may be bonded to each other to
form a ring; ##STR6## wherein each of R.sup.10 and R.sup.21, which
are independent of each other, is a C.sub.1-6 alkyl group, each of
R.sup.13 and R.sup.14 which are independent of each other, is a
hydrogen atom or a C.sub.1-6 alkyl group, Y is a sulfur atom, an
oxygen atom, dialkylmethylene or --N(R.sup.15)--, and R.sup.15 is a
hydrogen atom or a C.sub.1-6 alkyl group, provided that R.sup.10
and R.sup.11, R.sup.10 and R.sup.13, or R.sup.11 and R.sup.14, may
be bonded to each other to form a ring. Here, the carbon number of
each alkyl group in the dialkylmethylene ranges from 1 to 6,
preferably 1.
[0066] In a case where a pair of two of R.sup.2 to R.sup.14 is
bonded to form a ring, preferred is a 5- or 6-membered ring, and
particularly preferred is a 6-membered ring.
[0067] Suitable compounds represented by formula (IIIa), include
4,4'-dimethylaminobenzophenone, 4,4'-diethylaminobenzophenone and
the following compounds: ##STR7##
[0068] The compound having formula (IIIb) may be
2-(p-dimethylaminophenyl)benzooxazole,
2-(p-diethylaminophenyl)benzooxazole,
2-(p-dimethylaminophenyl)benzo[4,5]benzooxazole,
2-(p-dimethylaminophenyl)benzo[6,7]benzooxazole,
2,5-bis(p-diethylaminophenyl)1,3,4-oxazole,
2-(p-dimethylaminophenyl)benzothiazole,
2-(p-diethylaminophenyl)benzothiazole,
2-(p-dimethylaminophenyl)benzimidazole,
2-(p-diethylaminophenyl)benzimidazole or the following compound:
##STR8##
[0069] As a dialkylaminobenzene compound other than those of the
formulae (IIIa) and (IIIb),
2,5-bis(p-diethylaminophenyl)1,3,4-thiadiazole,
(p-dimethylaminophenyl)pyridine, (p-diethylaminophenyl)pyridine,
2-(p-dimethylaminophenyl)quinoline,
2-(p-diethylaminophenyl)quinoline,
2-(p-dimethylaminophenyl)pyrimidine or
2-(p-diethylaminophenyl)pyrimidine may, for example, be
mentioned.
[0070] Here, in view of the important factor of the handling
efficiency of a photosensitive composition under a yellow lamp,
particularly in order that the ratio of S410/S450 is at most 0.1,
preferred is a photopolymerization initiation system consisting of
a combination of the hexaarylbiimidazole compound as the radical
generator (C) with the dialkylaminobenzene compound as the
sensitizing agent (B).
[0071] Further, the photosensitive composition of the present
invention, which is to be exposed to violaceous light, preferably
contains a hydrogen-donor compound component as a polymerization
accelerator in addition to the above components, for the purpose of
improving photopolymerization initiation performance.
[0072] Specific examples of the hydrogen-donor compound include
compounds having a mercapto group such as 2-mercaptobenzothiazole,
2-mercaptobenzimidazole, 2-mercaptobenzoxazole and
3-mercapto-1,2,4-triazole, N,N-dialkyl benzoic alkyl ester,
N-aryl-a-amino acids, their salts and esters such as
N-phenylglycine, salts of N-phenylglycine, and alkyl esters of
N-phenylglycine such as N-phenylglycine ethyl ester and
N-phenylglycine benzyl ester, and compounds represented by the
following formula (IV): ##STR9## wherein R.sup.16 is a hydrogen
atom or an alkyl group which may have a substituent, R.sup.17 is a
hydrogen atom, an alkyl group which may have a substituent, a vinyl
group which may have a substituent, an aryl group which may have a
substituent, a (meth)acryloyl group which may have a substituent,
an aryl group which may have a substituent or an aromatic
heterocyclic group which may have a substituent, and the benzene
ring of the compound may have a substituent, and p is a integer
ranging from 2 to 10.
[0073] The photosensitive lithographic printing plate of the
present invention preferably contains a polymer binder in addition
to the above components in the photosensitive layer, for the
purpose of improving, e.g. development properties or coating
properties, when the photosensitive layer is coated on a
substrate.
[0074] Specific examples of the polymer binder include homopolymers
and copolymers of, e.g. (meth)acrylic acid, (meth)acrylic ester,
(meth)acrylamide, maleic acid, (meth)acrylonitrile, styrene, vinyl
acetate, vinylidene chloride and maleimide, and polyethylene oxide,
polyvinyl pyrrolidone, polyamide, polyurethane, polyester,
polyether, polyethylene terephthalate, acetyl cellulose and
polyvinyl butyral.
[0075] Of these binder materials, preferred is a copolymer
containing carboxyl groups in its molecule and containing, as
copolymerizable components, (meth)acrylic acid and at least one
(meth)acrylate which may be substituted, such as
methyl(meth)acrylate, ethyl(meth)acrylate, propyl(meth)acrylate,
butyl(meth)acrylate, 2-ethylhexyl(meth)acrylate,
hydroxyethyl(meth)acrylate or benzyl(meth)acrylate (hereinafter
referred to as "carboxyl group-containing copolymer").
[0076] The acid value of the carboxyl group-containing polymer
binder preferably ranges from 10 to 250 KOHmg/g, and the weight
average molecular weight calculated as polystyrene (hereinafter
referred to simply as Mw) preferably ranges from 5,000 to
1,000,000, more preferably from 10,000 to 500,000. Such a polymer
binder preferably has unsaturated bonds in its side chains, and a
resin obtained by reacting a compound having both epoxy group and
unsaturated group with the above carboxyl group-containing
copolymer may be mentioned.
[0077] Suitable compounds having both an epoxy group and an
unsaturated group include aliphatic epoxy group-containing
unsaturated compounds such as allyl glycidyl ether,
glycidyl(meth)acrylate, a-ethylglycidyl(meth)acrylate, glycidyl
crotonate, glycidyl isocrotonate, crotonyl glycidyl ether,
monoalkyl monoglycidyl itaconate, monoalkyl monoglycidyl fumarate
or monoalkyl monoglycidyl maleate, or
3,4-epoxycyclohexylmethyl(meth)acrylate. Of these compounds,
preferred is allyl glycidyl ether, glycidyl(meth)acrylate or
3,4-epoxycyclohexylmethyl(meth)acrylate, and more preferred is
3,4-epoxycyclohexylmethyl(meth)acrylate.
[0078] Also preferred is a compound having the structural unit
(monomer unit) represented by the following formula (V): ##STR10##
wherein Re is a hydrogen atom or a methyl group.
[0079] Of the above-mentioned resins having both carboxyl groups
and double bonds in their side chains, a preferred molecular
weight, Mw ranges from 10,000 to 1,000,000, preferably from 20,000
to 500,000. Further, preferred is a resin having from 1 to 50,
preferably from 5 to 40 units of double bonds introduced into the
side chains based on 100 monomer units of the main chain.
[0080] The photosensitive lithographic printing plate of the
present invention preferably contains, in the photosensitive layer,
an amine compound having a pKb (dissociation constant) of at most 7
at 25.degree. C. or an amino compound having an atomic group
[N--CH.sub.2] in its molecule, for the purpose of improving
sensitivity to laser light having a wavelength within a range
ranging from 390 to 430 nm. The photosensitive lithographic
printing plate more preferably contains, in the photosensitive
layer, an amine compound having a pKb of at most 7 at 25.degree. C.
and has the group [N--CH.sub.2] in its molecule.
[0081] The amine compound may be any one of aliphatic, alicyclic
and aromatic amines so long as the above conditions are satisfied,
and the hydrocarbon group in said amine may have a substituent.
Further, the amine compound is not limited to a monoamine, since it
may be a polyamine such as a diamine or a triamine, and it may be a
primary amine, a secondary amine or a tertiary amine. However, in
view of pKb values, an aliphatic amine having a hydrocarbon group
which may have a substituent is, much preferred and a tertiary
amine is particularly preferred.
[0082] The pKb value of the amine is preferably at most 5. Further,
the lower limit of the pKb value is preferably at least 3. Further,
an amine having the group [CH.sub.2--N--CH.sub.2] in its molecule
is more preferred.
[0083] Specifically, an aliphatic amine which may be replaced with
a hydroxyl group or a phenyl group, such as butylamine,
dibutylamine, tributylamine, amylamine, diamylamine, triamylamine,
hexylamine, dihexylamine, trihexylamine, benzylamine,
dibenzylamine, tribenzylamine, triethanolamine, allylamine,
diallylamine or triallylamine, may be mentioned.
[0084] As the amine compound for use in the present invention,
since it practically has to remain in the photosensitive layer when
the photosensitive layer is coated and dried, and since it has to
be used without presenting any problems in handling such as odor, a
preferred amine compound is one which has a boiling point of at
least 80.degree. C. under normal pressure, and particularly
preferred is one which has a boiling point of at least 150.degree.
C. and which is solid at room temperature (25.degree. C.). Further,
a triaralkyl amine is preferred since it does not decrease the
dispersibility of the coloring pigment. From this viewpoint, and
taking availability into consideration, tribenzylamine is a
particularly preferred example.
[0085] The reasons for improvement in sensitivity as a result of
addition of the amine are believed to be as follows.
[0086] (1) The formation of active amino radicals by a chain
transfer reaction of an amine with radicals generated in the
photopolymerization initiation mechanism or polyacrylate radicals
formed by photopolymerization of an acrylate monomer by the action
of the radicals.
[0087] (2) In a sensitizing step by electron transfer from a light
excitation sensitizing agent to a radical generator, the
sensitizing agent cation and radical generator anion are formed,
but in general, a reverse electron transfer to the pigment cation
deactivates the radical generator anion. The amine transfers
electron to the sensitizing agent cation and changes the cation to
a neutral sensitizing agent, and it thereby suppresses the reverse
electron transfer, increases decomposition efficiency of the
radical generator anion, and increases the radical generation
effect.
[0088] (3) The amine significantly increases the elution rate
particularly of the non-image portion or a photosensitive layer in
an inadequately cured state to an alkali developer at the time of
alkali development, and it thereby prevents loss of the photo-set
photosensitive layer and increases sensitivity.
[0089] For the photosensitive layer of the photosensitive
lithographic printing plate of the second aspect of the present
invention, a combination of the above ethylenic monomer, the
hexaarylbiimidazole compound (radical generator) and the
dialkylaminobenzene compound (sensitizing agent), as the
photopolymerization initiation system, or a combination of the
above ethylenic monomer, the titanocene compound (radical
generator) and the dialkylaminobenzene compound (sensitizing agent)
is essential. The compounding ratio of each component of the
composition, based on 100 parts by weight of the ethylenic monomer,
is such that the amount of the hexaarylbiimidazole compound
preferably ranges from 5 to 60 parts by weight, more preferably
from 15 to 40 parts by weight, the amount of the titanocene
compound preferably ranges from 1 to 30 parts by weight, more
preferably from 5 to 20 parts by weight, and the amount of the
dialkylaminobenzene compound preferably ranges from 1 to 30 parts
by weight, more preferably from 5 to 20 parts by weight. Further,
the compositional ratio of the sensitizing agent to the radical
generator is such that the dialkylaminobenzene compound preferably
ranges from 0.1 to 5 parts by weight, more preferably from 0.2 to 3
parts by weight, based on 1 part by weight of the
hexaarylbiimidazole compound, and the dialkylaminobenzene compound
ranges from 0.5 to 6 parts by weight, more preferably from 0.5 to
1.8 parts by weight, based on 1 part by weight of the titanocene
compound.
[0090] Further, in the case where the polymerization accelerator
(hydrogen-donor compound) is incorporated in the composition for
the purpose of improving photopolymerization initiation
performance, it is incorporated in an amount preferably ranging
from 1 to 50 parts by weight, more preferably from 10 to 40 parts
by weight, based on 100 parts by weight of the ethylenic monomer
component.
[0091] Further, in the case where the polymer binder is
incorporated in the composition, it is incorporated in an amount
preferably ranging from 50 to 500 parts by weight, more preferably
from 70 to 200 parts by weight, based on 100 parts by weight of the
ethylenic monomer.
[0092] The photosensitive layer of the lithographic printing plate
to be used in the present invention may contain another substance
depending upon the purpose for its use. For example, a coating
property-improving agent such as a nonionic, anionic, cationic or
fluorine type surface active agent; a thermal polymerization
inhibitor such as hydroquinone, p-methoxyphenol or
2,6-di-t-butyl-p-cresol; a coloring pigment of an organic or
inorganic dye or pigment (which is different from the above
sensitizing agent, which is substantially incompatible with a
coating solvent or a photosensitive layer component, and which has
no sensitizing function); a plasticizer such as dioctyl phthalate,
didodecylphthalate or tricresyl phosphate; a sensitivity
properties-improving agent such as a tertiary amine or a thiol; or
another additive such as a pigment precursor, an antifoaming agent,
a visible image-imparting agent, an adhesion-improving agent, a
development property-improving agent or an ultraviolet absorber,
may be added.
[0093] With respect to preferred amounts of the above additives
based on 100 parts by weight of the ethylenic monomer, the thermal
polymerization inhibitor is at most 2 parts by weight, the coloring
pigment is at most 20 parts by weight, the plasticizer is at most
40 parts by weight, the pigment precursor is at most 30 parts by
weight, and the surface active agent is at most 10 parts by
weight.
[0094] Particularly, if the content of the coloring pigment is too
high, the performance of the present invention may be inadequate.
Accordingly, the content of the coloring pigment is preferably at
most 20 wt % of the photosensitive composition.
[0095] The above photosensitive composition is diluted with a
proper solvent, and coated and dried on a support to form the
photosensitive layer.
[0096] The support which is used in the present invention may be
any of the conventional ones used for photosensitive lithographic
printing plates, and it may, for example, be a metal plate of,
e.g., aluminum, zinc, iron, copper or an alloy thereof, a metal
plate having chromium, zinc, copper, nickel, aluminum, iron or the
like plated or vapor-deposited thereon, a paper sheet, a plastic
film, a glass sheet, a resin-coated paper sheet, a paper sheet
having a metal foil such as an aluminum foil bonded thereto, or a
plastic film having hydrophilic treatment applied thereto. Among
them, preferred is a plate of aluminum or an aluminum alloy
(hereinafter referred to as an aluminum support).
[0097] The thickness of the aluminum support is usually ranges from
about 0.01 to about 10 mm, preferably from about 0.05 to about 1
mm.
[0098] The surface on at least the photosensitive layer composition
side of the aluminum support is subjected to surface roughening,
and then an anodic oxidation treatment is conducted. A degreasing
treatment, a sealing treatment, an undercoating treatment or the
like may further be conducted as the case requires. A degreasing
treatment is conducted usually before the surface roughening, and
the degreasing treatment is conducted in accordance with a
conventional method such as wiping, soaking or steam-washing the
support with a solvent, by soaking or spraying the support with an
aqueous alkali solution, followed by neutralization with an aqueous
acid solution, or by soaking or spraying the support with a surface
active agent. Surface roughening may be accomplished by a known
such as brush polishing, ball polishing, electrolytic etching,
chemical etching, liquid honing or sand blasting, or a combination
thereof. Preferred is brush polishing, ball polishing, electrolytic
etching, chemical etching or liquid honing.
[0099] The aluminum plate which is surface is further subjected to
a desmutting treatment with an aqueous acid or alkali solution as
the case requires. The desmutting treatment is conducted by soaking
the plate in an aqueous solution of an acid such as sulfuric acid,
nitric acid, hydrochloric acid, phosphoric acid or chromic acid, or
in an aqueous solution of an alkali such as sodium hydroxide,
potassium hydroxide, sodium metasilicate, sodium phosphate, sodium
pyrophosphate, potassium phosphate or sodium aluminate, or by
spraying aqueous solutions onto the plate. The aluminum plate thus
obtained is usually subjected to an anodic oxidation treatment,
particularly preferably a treatment with an electrolytic solution
containing sulfuric acid. The method of anodic oxidation treatment
with an electrolytic solution containing sulfuric acid may be
conducted in accordance a known method such as disclosed in
JP-A-58-213894. Specifically, it is conducted, for example, at a
sulfuric acid content ranging from 5 to 50 wt %, preferably from 15
to 30 wt %, at a temperature ranging from about 5 to about
50.degree. C., preferably from 15 to 35.degree. C., at a current
density ranging from 1 to 60 A/dm.sup.2 for from about 5 to about
60 seconds. Further, as the case requires, the substrate surface
may be treated with hot water or with an alkali silicate such as a
silicate of soda, or by soaking the plate in an aqueous solution
containing an aqueous polymer compound such as polyvinyl phosphonic
acid or a resin having a cationic quaternary ammonium group. The
thickness of the aluminum support usually from 0.01 to 10 mm,
preferably from about 0.05 to about 1 mm, and with respect to the
surface roughness, the average roughness Ra as stipulated in JIS
B0601 usually ranges from 0.3 to 1.0 .mu.m, preferably from about
0.4 to about 0.8 .mu.m.
[0100] The photosensitive lithographic printing plate used in the
present invention is exposed by means of a laser light relatively
low exposure. Accordingly, it is effective to leave smut on the
surface of the substrate so as to increase the adhesion of the
photosensitive composition, within a range not influence such as
staining during printing or impairing development properties. The
residual amount of the smut preferably ranges from 0.3 to 0.5, more
preferably from 0.32 to 0.45, as by the reflection density on the
surface the photosensitive composition side. When the reflection
ratio is within the above range, printing resistance will
improve.
[0101] Further, in the case where the desmutting treatment is
conducted, it is preferred to control the desmutting conditions so
that 0.01.ltoreq.D-E.ltoreq.0.1, where D is the reflection density
on the surface at the photosensitive composition side immediately
after the surface roughening treatment, and E is the reflection
density on the surface the photosensitive composition side after
the anodic oxidation treatment. More preferably,
0.01.ltoreq.D-E.ltoreq.0.08.
[0102] The reflection density is measured by means of a reflection
densitometer visual mode without using a filter. The desmutting of
a surface may be performed by soaking the substrate in an aqueous
NaOH solution at a concentration preferably ranging from 0.1 to 4
wt %, at a liquid temperature ranging from about 5 to about
30.degree. C. for from about 1 to about 10 seconds, depending on
the state of the surface roughening and the aqueous alkali solution
used.
[0103] The photosensitive composition may be coated on a surface by
a known method such as by dip coating, coating by means of a rod,
spinner coating, spray coating or roll coating. The amount coated
ranges from 0.5 to 5 g/m.sup.2. Here, the temperature for drying
ranges from about 30 to about 150.degree. C., preferably from about
40 to about 110.degree. C., and the drying time ranges from about 5
seconds to about 60 minutes, preferably from about 10 seconds to
about 30 minutes.
[0104] A protective layer (oxygen-shielding layer) is provided on
the photosensitive layer in order to prevent polymerization
inhibition due to the presence of oxygen. Specific examples of
protective layers are those formed from water-soluble polymers such
as a polyvinyl alcohol, polyvinyl pyrrolidone, polyethylene oxide
and cellulose. Among them, preferred is a polyvinyl alcohol having
high oxygen gas barrier properties. It is also preferred to use a
polyvinyl alcohol and polyvinyl pyrrolidone in combination, and in
this case, preferably from 1 to 20 parts by weight, more preferably
from 3 to 15 parts by weight, of polyvinyl pyrrolidone is used
based on 100 parts by weight of the polyvinyl alcohol.
[0105] The photosensitive lithographic printing plate of the
present invention may be formed in a manner such that the
photosensitive layer of a photosensitive composition having a
maximum peak of spectral sensitivity outside the wavelength range
from 370 to 430 nm, then a protective layer transmission of light
is formed on the photosensitive layer so as to form, for example, a
layer made of a photosensitive composition having a maximum peak of
spectral sensitivity within a wavelength range ranging from 430 to
460 nm, and on photosensitive layer, a protective layer showing
absorption within a range ranging from 430 to 500 nm is formed, so
that the maximum peak of spectral sensitivity is within a
wavelength range ranging from 400 to 420 nm, and the absolute
sensitivity is at most 100 .mu.J/cm.sup.2 at a wavelength of 410 nm
resultingly.
[0106] A preferred aspect of the invention is that the
photosensitive composition which constitutes the photosensitive
layer in the above case, is one in which the polymerization
initiation system is changed, specifically to a combination of the
above titanocene compound with a coumarin compound. coumarin
pigments as disclosed in e.g. JP-A-6-301208, JP-A-8-146605,
JP-A-8-211605, JP-A-8-129258 or JP-A-8-129259. The coumarin pigment
is a pigment which has the following skeleton in its structure.
##STR11##
[0107] In the case of forming a photosensitive layer using a
photosensitive composition which undergoes photo-radical
polymerization, an oxygen-shielding layer is preferably formed on
the photosensitive layer as mentioned above so as to prevent
radical polymerization inhibition due to the action of oxygen, and
it is possible to employ the oxygen-shielding layer as a protective
layer and to adjust the components in the protective layer to
adjust the maximum peak of spectral sensitivity as photosensitive
lithographic printing plate to within a wavelength range ranging
from 400 to 440 nm. The protective layer may contain a
water-soluble polymer similar to one in the above oxygen-shielding
layer as the main component, and contains a compound which absorbs
light having the above desired wavelength.
[0108] The third aspect of the invention of making a printing plate
using the photosensitive lithographic printing plate of the present
invention is as follows.
[0109] In order to prepare the printing plate of the present
invention, the lithographic printing plate of the invention is
exposed by means of a laser having a wavelength ranging from 390 to
430 nm, followed by development to remove non-exposed portions of
the photosensitive layer to form an image.
[0110] The source of light for image formation is not particularly
limited long as it is laser light having an oscillation wavelength
ranging from 390 to 430 nm. Preferred is laser light having an
oscillation wavelength ranging from 400 to 420 nm, and particularly
advantageous is an indium gallium nitride semiconductor laser
emitting light having a wavelength in the vicinity of 410 nm.
[0111] Exposure of the photosensitive lithographic printing plate
is conducted by employing a laser beam having an oscillation
wavelength ranging from 390 to 430 nm, preferably from 400 to 420
nm, as a beam spot having a diameter ranging from 2 to 30 .mu.m,
preferably from 4 to 20 .mu.m, at an output light intensity of the
laser ranging from 1 to 100 mW, preferably from 3 to 70 mW, and by
moving the beam spot at a scanning rate ranging from 50 to 500 m/s,
preferably from 100 to 400 m/s.
[0112] Image-exposure is conducted so that exposure of the
photosensitive lithographic printing plate (printing plate
exposure) to laser light is at most 100 .mu.J/cm.sup.2, preferably
at most 50 .mu.J/cm.sup.2. The lower limit is preferably as low as
possible, but is usually at least 1 .mu.J/cm.sup.2, and is
practically at least 5 .mu.J/cm.sup.2. Further, the higher the
scanning density upon exposure, the greater the high-definition
image formation. Accordingly, the scanning density is preferably at
least 2,000 dpi, more preferably at least 4,000 dpi.
[0113] The photosensitive lithographic printing plate of the
present invention is image-exposed by means of the above light
source, followed by development of the image with an aqueous
developer consisting mainly of water, preferably with an aqueous
solution containing a surface active agent and an alkali
component.
[0114] The aqueous solution may further contain an organic solvent
or a buffering agent. A preferred buffering agent is an alkali
component such as an inorganic alkali such as sodium silicate,
potassium silicate, sodium hydroxide, potassium hydroxide, lithium
hydroxide, tribasic sodium phosphate, dibasic sodium phosphate,
sodium carbonate, potassium carbonate and sodium bicarbonate, an
organic amine compound such as trimethylamine, diethylamine,
isopropylamine, n-butylamine, monoethanolamine, diethanolamine and
triethanolamine. These compounds may be used alone or in
combination. The pH of the alkali developer usually ranges from
about 9 to about 14, preferably from 11 to 14.
[0115] Surface active agents include a nonionic surface active
agent such as a polyoxyethylene alkyl ether, a polyoxyethylene
alkyl aryl ether, a polyoxyethylene alkyl ester, a sorbitan alkyl
ester or a monoglyceride alkyl ester, an anionic surface active
agent such as an alkyl benzene sulfonate, an alkyl naphthalene
sulfonate, an alkyl sulfate, an alkyl sulfonate or a
sulfosuccinate, or an ampholytic surface active agent such as an
alkyl betaine or an amino acid. Further, suitable organic solvents
include isopropyl alcohol, benzyl alcohol, ethyl cellosolve, butyl
cellosolve, phenyl cellosolve, propylene glycol and diacetone
alcohol.
[0116] The method of development employed is not particularly
limited, and may be conducted by soaking and shaking the plate in a
developer, physically removing non-image portions which is at the
point of being dissolved in a developer by means of e.g. a brush,
or spraying a developer onto the plate so as to remove non-image
portions. The time for development is selected depending upon the
above method used so that the non-image portions can adequately be
removed, and is optionally selected within a range of 5 seconds to
10 minutes.
[0117] After the development, the plate may be subjected to a
hydrophilic treatment by means of, e.g., gum arabic optionally
applied to the printing plate as the case requires. Further, the
oxygen-shielding layer may be initially washed with water before
development as the case requires.
[0118] Having now generally described this invention, a further
understanding can be obtained by reference to certain specific
examples which are provided herein for purposes of illustration
only and are not intended to be limiting unless otherwise
specified.
Preparation of an Aluminum Support (1)
[0119] An aluminum plate having a thickness of 0.3 mm was degreased
with a 3 wt % aqueous sodium hydroxide solution, subjected to
electrolytic etching in a hydrochloric acid bath of 11.5 g/l at
25.degree. C. at a current density of 80 A/dm.sup.2 for 11 seconds,
and washed with water. Then, the plate was subjected to anodic
oxidation in a sulfuric acid bath of 30 wt % at 30.degree. C. at
11.5 A/dm2 for 15 seconds, washed with water and dried to prepare
an aluminum plate as a lithographic printing plate (hereinafter
referred to simply as support (1)).
Preparation of an Aluminum Support (2)
[0120] An aluminum plate (thickness: 0.24 mm) was degreased with a
3 wt % aqueous sodium hydroxide solution, and subjected to
electrolytic etching in a nitric acid bath of 18.0 g/l at
25.degree. C. at a current density of 90 A/dm.sup.2 for 11 seconds.
Then, the plate was subjected to desmutting in a 4.5 wt % aqueous
sodium hydroxide solution at 30.degree. C. for 2 seconds,
neutralized in a 10 wt % aqueous nitric acid solution at 25.degree.
C. for 5 seconds, washed with water, and then subjected to an
anodic oxidation treatment in a nitric acid bath of 30 wt % at
30.degree. C. at a current density of 10 A/dm.sup.2 for 16 seconds,
and washed with water and dried to prepare a support.
[0121] The reflection density of the support (measured by a
reflection densitometer (RD-918 manufactured by Macbeth) was 0.32.
Further, during this production step, A-B=0.08 (where A is the
reflection density on the surface at the photosensitive composition
side immediately after the surface roughening treatment, and B is
the reflection density on the surface at the photosensitive
composition side immediately before the anodic oxidation
treatment).
[0122] Hereinafter the support thus obtained will be referred to
simply as "support (2)".
EXAMPLES 1 TO 15 AND COMPARATIVE EXAMPLES 1 TO 5
[0123] A coating fluid of the following photosensitive composition
was coated onto support (1) by means of a bar coater and dried so
that the dried film thickness became 2 g/m.sup.2 (drying condition:
170.degree. C., 2 minutes). Further, the following protective layer
coating fluid (1) was coated thereon by means of a bar coater and
dried so that the dried film thickness became 3 g/m.sup.2 (drying
condition: 170 C, 2 minutes) to prepare a photosensitive
lithographic printing plate. TABLE-US-00001 Protective layer
coating fluid (1) Polyvinyl alcohol (GL-03 manufactured by 90 parts
by weight Nippon Synthetic Chemical Industry Co., Ltd.) Polyvinyl
pyrrolidone (Mw = 4,000) 5 parts by weight Water 1,000 parts by
weight
[0124] TABLE-US-00002 Photosensitive composition coating fluid
Radical generator (compound as Amount as shown in Table 1
identified in Table 1) Sensitizing agent (compound as Amount as
shown in Table 1 identified in Table 1) Polymer binder (the
following 45 parts by weight compound P-1) Ethylenic monomer 1 (the
following Amount as shown in Table 1 compound E-1) Ethylenic
monomer 2 (the following 22 parts by weight compound E-2) Ethylenic
monomer 3 (the following Amount as shown in Table 1 compound E-3)
Ethylenic monomer 4 (the following Amount as shown in Table 1
compound E-4) 2-mercaptobenzothiazole 5 parts by weight
N-phenylglycine benzylester Amount as shown in Table 1
Tribenzylamine Amount as shown in Table 1 Copper phthalocyanine
pigment 4 parts by weight (visible image agent) Emulgen 104 P
(surface active agent, 2 parts by weight manufactured by Kao
Corporation) S-381 (fluorine type surface active 0.3 part by weight
agent, manufactured by Asahi Glass Company, Limited) Disperbyk 161
(dispersing agent, 2 parts by weight manufactured by Big Chemie)
Propylene glycol monomethyl ether 400 parts by weight acetate
Cyclohexanone 740 parts by weight
[0125] Among the components of the photosensitive composition, the
structures of the radical generator, the sensitizing agent, the
polymer binder and the ethylenic monomer are as follows: Radical
Generator ##STR12## Sensitizing Agent ##STR13## Polymer Binder
##STR14## Ethylenic Monomer ##STR15##
[0126] The obtained photosensitive lithographic printing plate for
violaceous laser exposure was evaluated with respect to the
following items. The results are shown in Table 1.
Evaluation of Sensitivity
[0127] The prepared photosensitive lithographic printing plate was
cut into a size of 50.times.60 mm, and the photosensitive material
sample was irradiated for 10 seconds with a light of which light
intensity logarithmically decreased in the vertical axis, and the
light wavelength linearly decreased in the horizontal axis, as
determined by means of a diffraction spectral irradiation apparatus
(RM-23, manufactured by Narumi K.K.) equipped with xenon lamp
U1-501C (1 kW: manufactured by Ushio Inc.) as a light source. The
exposed sample was soaked in an aqueous solution containing 0.7 wt
% of sodium carbonate and 0.5 wt % of an anionic surface active
agent (Pelex NBL, manufactured by Kao Corporation) at 28.degree. C.
for 30 seconds to develop the image. After development, the minimum
amount of exposure energy required for photocuring by light
radiation of 410 nm was calculated from the height of the cured
image obtained. The smaller amount of energy, the higher the
sensitivity.
S410/S450
[0128] The photosensitive material sample was exposed and developed
in the same manner as described in the above evaluation of
sensitivity, whereupon the minimum exposure energy S410
(.mu.J/cm.sup.2 ) at a wavelength of 410 nm and the minimum
exposure energy S450 (.mu.J/cm.sup.2) at a wavelength of 450 nm
were obtained to calculate the ratio (S410/S450).
[0129] Here, the symbols A to D in the column of minimum exposure
energy in Table 1 represent the following.
[0130] A: S410/S450 is at most 0.03
[0131] B: S410/S450 exceeds 0.03 and is at most 0.1
[0132] C: S410/S450 exceeds 0.1 and is at most 0.5
[0133] D: S410/S450 exceeds 0.1
[0134] The smaller the ratio, the better the safe light properties
under a yellow lamp.
Maximum Peak of Spectral Sensitivity
[0135] The photosensitive material sample was exposed and developed
in the same manner as described in the above evaluation of
sensitivity, whereupon a spectral sensitivity curve was obtained
with the horizontal axis indicating the exposure wavelength and the
vertical axis indicating the inverse of the minimum exposure energy
(sensitivity) at the wavelength indicated by the horizontal axis,
and from the spectral sensitivity curve, a wavelength showing the
maximum peak of spectral sensitivity was obtained. Here, the
exposure wavelength was changed from 350 nm to 650 nm.
Safe Light Properties Under a Yellow Lamp
[0136] The photosensitive lithographic printing plate was cut into
a size of 30.times.30 mm, and each sample was left to stand under a
yellow lamp (under the condition of being shielded from light
having wavelengths of at most about 470 nm) for 1 minute, 2
minutes, 5 minutes, 10 minutes, 20 minutes, 30 minutes or 40
minutes, followed by development in the same manner as described
above, to obtain the maximum time for which the photosensitive
composition left to stand under a yellow lamp would not cure
(evaluation of 40 minutes at the most).
[0137] Here, symbols A to D in the column of safe light properties
in Table 1 mean the following.
[0138] A: At least 20 minutes
[0139] B: At least 10 minutes and less than 20 minutes
[0140] C: At least 1 minute and less than 10 minutes
[0141] D: Less than 1 minute
EXAMPLE 15
[0142] A photosensitive lithographic printing plate was prepared in
the same manner as described in Example 12 by successively coating
and drying the photosensitive composition coating fluid and the
protective layer coating fluid, except that the support (2) was
used instead of the support (1), and evaluations were conducted in
the same manner. The results are shown in Table 1. TABLE-US-00003
TABLE 1 Amount of Amount of Amount of Radical Sensitizing Absorp-
ethylenic ethylenic ethylenic generator pigment tion monomer-1
monomer-3 monomer-4 (part by (part by maximum (part by (part by
(part by weight) weight) (nm) weight) weight) weight) Ex. 1 R-1
(15) S-1 (9) 410 (22) (11) (0) Ex. 2 R-1 (10) S-1 (6) 410 (22) (11)
(0) Ex. 3 R-3 (5) S-1 (3) 410 (22) (11) (0) Ex. 4 R-1 (10) S-1 (6)
410 (22) (11) (0) Ex. 5 R-1 (10) S-1 (6) 410 (0) (11) (33) Ex. 6
R-2 (15) S-1 (9) 410 (0) (11) (22) Ex. 7 R-2 (15) S-1 (6) 410 (0)
(11) (22) Ex. 8 R-2 (10) S-1 (6) 410 (0) (11) (22) Ex. 9 R-2 (5)
S-1 (6) 410 (0) (11) (22) Ex. 10 R-1 (5) S-1 (4.5) 410 (0) (11)
(22) Ex. 11 R-3 (5) S-1 (3) 410 (0) (11) (22) Ex. 12 R-1 (15) S-1
(9) 410 (11) (6) (22) Ex. 13 R-1 (15) S-1 (9) 410 (11) (6) (22) Ex.
14 R-3 (15) S-1 (9) 410 (11) (6) (22) Comp. Ex. 1 R-3 (5) S-2 (3)
450 (0) (11) (22) Comp. Ex. 2 R-2 (15) S-4 (9) Not (0) (11) (22)
measured Comp. Ex. 3 R-2 (15) S-4 (9) Not (22) (11) (0) measured
Comp. Ex. 4 R-3 (5) S-2 (3) 450 (22) (11) (0) Comp. Ex. 5 R-3 (5)
S-2 (3) 450 (0) (11) (33) Ex. 15 R-1 (15) S-1 (9) 410 (11) (6) (22)
Amount of N- phenylglycine Amount of benzyl ester tribenzylamine
S410 Safe light (part by weight) (part by weight) (.mu.J/cm.sup.2)
S410/S450 properties Ex. 1 (5) (3) 14 0.026 20 min. Ex. 2 (5) (3)
15 B 40 min. Ex. 3 (5) (3) 18 C 40 min. Ex. 4 (5) (0) 22 B 40 min.
Ex. 5 (5) (3) 24 B 40 min. Ex. 6 (5) (0) 24 0.026 30 min. Ex. 7 (5)
(0) 24 0.038 30 min. Ex. 8 (5) (0) 30 0.032 40 min. Ex. 9 (5) (0)
43 At most 40 min. 0.021*.sup.2 Ex. 10 (5) (0) 54 At most 40 min.
0.027*.sup.2 Ex. 11 (5) (0) 54 0.38 1 min. Ex. 12 (3) (5) 15 A A
Ex. 13 (8) (3) 22 A A Ex. 14 (8) (0) 27 A A Comp. Ex. 1 (5) (0) 24
2.25 Nil Comp. Ex. 2 (5) (0) F.sup.+3 -- -- Comp. Ex. 3 (5) (3)
F.sup.+3 -- -- Comp. Ex. 4 (5) (3) 14 D D Comp. Ex. 5 (5) (3) 21 D
D Ex. 15 (3) (5) 15 A D *1: "Nil" means that the plate was cured
after having been left to stand for 1 minute. *.sup.2It was
impossible to form an image with an energy of about 2,000
.mu.J/cm.sup.2 by exposure at a wavelength of 450 nm under the
above conditions. .sup.+3"F" means that it was impossible to form
an image with an energy of about 2,000 .mu.J/cm.sup.2 by exposure
at a wavelength of 410 nm under the above conditions.
[0143] From the evaluation above of spectral sensitivity, the
minimum exposure for image formation for each of the photosensitive
material samples of Examples 1 to 15 at a wavelength longer than
450 nm was higher than the value at a wavelength of 450 nm. On the
other hand, the minimum exposure for image formation for the
photosensitive material sample of Comparative Example 1 at a
wavelength longer than 450 nm was higher than the value at a
wavelength of 450 nm. Further, each of the photosensitive layers of
Examples 1 to 15 showed a maximum peak at 410 nm within a range
ranging from 350 to 650 nm.
EXAMPLE 16
[0144] A photosensitive lithographic printing plate prepared in the
same manner as described in Example 1 was image-exposed by means of
a 410 nm violaceous laser printing plate exposure apparatus (Cobalt
8) manufactured by Escher Glad at a laser light output of 0.5 mW
with a laser beam spot diameter of 12 .mu.m at a scanning density
of 5,080 dpi at a scanning rate of 167 m/s. The image-exposed
photosensitive lithographic printing plate was developed in the
same manner as described in Example 1, whereupon a print having a
high quality image was obtained. The printing plate exposure energy
was 30 .mu.J/cm.sup.2.
[0145] With respect to a photosensitive lithographic printing plate
prepared in the same manner as described in Examples 1 to 15, an
image can be formed by image exposure in the same manner as
described in Example 16 by means of a 410 nm violaceous laser
printing plate exposure apparatus (Cobalt 8) manufactured by Escher
Glad at a laser light output of 0.5 mW with a laser beam spot
diameter of 12 .mu.m, at a scanning density of 5,080 dpi at a
scanning rate of 167 m/s, followed by development.
[0146] The photosensitive lithographic printing plate of the
present invention is highly sensitive upon exposure to laser light
ranging from 390 to 430 nm, and accordingly an image can
efficiently be formed by means of laser light ranging in wavelength
from 390 to 430 nm.
[0147] Further, as a preferred embodiment, the composition exhibits
excellent safe light properties under a yellow lamp and exhibits
excellent handling efficiency.
[0148] The disclosures of Japanese Patent Application Nos.
2000-117803 filed on Apr. 19, 2000; 2000-131995 filed on May 1,
2000; 2000-131996 filed on May 1, 2000; 2000-364310 filed on Nov.
30, 2000; 2000-368412 filed on Dec. 4, 2000; 2000-369415 filed on
Dec. 5, 2000 and 2001-016537 filed on Jan. 25, 2001, including
specification, claims, drawings and summary are incorporated herein
by reference.
[0149] Obviously, numerous modifications and variations of the
present invention are possible in light of the above teachings. It
is therefore to be understood that within the scope of the appended
claims, the invention may be practiced otherwise than as
specifically described herein.
* * * * *