U.S. patent application number 09/874847 was filed with the patent office on 2001-10-25 for photosensitive resin composition and resin plate for flexography.
This patent application is currently assigned to Tokyo Ohka Kogyo Co., Ltd.. Invention is credited to Aoyama, Toshimi, Kahara, Koji, Kobayashi, Nobuhiro, Takagi, Toshiya, Yoshida, Masatoshi.
Application Number | 20010033981 09/874847 |
Document ID | / |
Family ID | 18106497 |
Filed Date | 2001-10-25 |
United States Patent
Application |
20010033981 |
Kind Code |
A1 |
Takagi, Toshiya ; et
al. |
October 25, 2001 |
Photosensitive resin composition and resin plate for
flexography
Abstract
The present invention provides a photosensitive resin
composition which comprises an urethane resin obtained by reacting
(A) a carboxyl group-containing polymer having an acid value of 30
mg KOH/g or more and a glass transition temperature of 30.degree.
C. or more, (B) a compound having two isocyanate groups in one
molecule, (C) a compound having two hydroxyl groups in one molecule
and (D) a photopolymerizable unsaturated monomer having one
hydroxyl group in one molecule, and a photopolymerization
initiator, and a resin plate for flexography using the
photosensitive resin composition, whereby the photosensitive resin
composition having water developing properties, high in sensitivity
and impact resilience, and excellent in water resistance, ink
resistance and press life of a hardened portion forming a line
pattern area of a printing plate material and the resin plate for
flexography prepared by the use of the photosensitive resin
composition can be provided.
Inventors: |
Takagi, Toshiya;
(Fujisawa-shi, JP) ; Kahara, Koji; (Osaka, JP)
; Aoyama, Toshimi; (Fujisawa-shi, JP) ; Kobayashi,
Nobuhiro; (Osaka, JP) ; Yoshida, Masatoshi;
(Nara-shi, JP) |
Correspondence
Address: |
JOHN B. PEGRAM
Fish & Richardson P.C.
Suite 2800
45 Rockefeller Plaza
New York
NY
10111
US
|
Assignee: |
Tokyo Ohka Kogyo Co., Ltd.
|
Family ID: |
18106497 |
Appl. No.: |
09/874847 |
Filed: |
June 5, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
09874847 |
Jun 5, 2001 |
|
|
|
09308783 |
May 25, 1999 |
|
|
|
Current U.S.
Class: |
430/18 ;
430/284.1; 430/306; 522/97 |
Current CPC
Class: |
C08G 18/8175 20130101;
C08G 18/672 20130101; C08G 18/4018 20130101; G03F 7/0388 20130101;
C08G 18/67 20130101; G03F 7/035 20130101 |
Class at
Publication: |
430/18 ;
430/284.1; 430/306; 522/97 |
International
Class: |
G03F 007/028; G03F
007/038 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 5, 1997 |
JP |
HEI.9-319102 |
Claims
1. A photosensitive resin composition comprising an urethane resin
obtained by reacting (A) a carboxyl group-containing polymer having
an acid value of 30 mg KOH/g or more and a glass transition
temperature of 30.degree. C. or more, (B) a compound having two
isocyanate groups in one molecule, (C) a compound having two
hydroxyl groups in one molecule and (D) a photopolymerizable
unsaturated monomer having one hydroxyl group in one molecule, and
a photopolymerization initiator.
2. A photosensitive resin composition comprising an urethane resin
obtained by reacting (A) a carboxyl group-containing polymer having
an acid value of 30 mg KOH/g or more and a glass transition
temperature of 30.degree. C. or more, (B) a compound having two
isocyanate groups in one molecule, (C) a compound having two
hydroxyl groups in one molecule and (D) a photopolymerizable
unsaturated monomer having one hydroxyl group in one molecule, a
photopolymerizable unsaturated monomer and a photopolymerization
initiator.
3. A photosensitive resin composition comprising an urethane resin
comprising as structural units (A) a carboxyl group-containing
polymer having an acid value of 30 mg KOH/g or more and a glass
transition temperature of 30.degree. C. or more, (B) a compound
having two isocyanate groups in one molecule, (C) a compound having
two hydroxyl groups in one molecule and (D) a photopolymerizable
unsaturated monomer having one hydroxyl group in one molecule, and
a photopolymerization initiator.
4. The photosensitive resin composition according to any one of
claims 1 to 3, wherein said urethane resin is a resin obtained by
reacting component (B), component (C), component (D) and component
(A) in this order.
5. The photosensitive resin composition according to any one of
claims 1 to 4, wherein component (A) is an acrylic polymer.
6. The photosensitive resin composition according to any one of
claims 1 to 4, wherein component (B) is hexamethylene
diisocyanate.
7. The photosensitive resin composition according to any one of
claims 1 to 5, wherein component (C) is polyether diol.
8. The photosensitive resin composition according to any one of
claims 1 to 4, wherein component (D) is a hydroxyl group containing
unsaturated acrylic acid ester series monomer.
9. The photosensitive resin composition according to claim 8,
wherein the hydroxyl group-containing unsaturated acrylic acid
ester series monomer is 2-hydroxyethyl acrylate.
10. A resin plate for flexography using the photosensitive resin
composition of any one of claims 1 to 9.
11. A resin plate for flexography, which uses the photosensitive
resin composition of any one of claims 1 to 9 and has a
photosensitive resin layer having an impact resilience of 30% or
more according to JIS K6301-11.
Description
TECHNICAL FIELD OF THE INVENTION
[0001] The present invention relates to a photosensitive resin
composition, and more particularly to a photosensitive resin
composition suitable for a plate for aqueous flexography and a
resin plate for flexography using the photosensitive resin
composition.
TECHNICAL BACKGROUND
[0002] Conventionally, thermoplastic elastomers having appropriate
impact resilience or photosensitive resin compositions comprising
photopolymerizable unsaturated monomers and photopolymerization
initiators have been used as photosensitive resin compositions for
forming photosensitive resin layers of photosensitive resin plates
for flexography. As the above-mentioned thermoplastic elastomers,
for example, styrenic resins such as styrene/isoprene/styrene and
styrene/butadiene/styrene have been used. However, these
thermoplastic elastomers are hydrophobic, so that they can not be
extracted with water or aqueous solvents. Accordingly, chlorine
series organic solvents such as chloroform, trichloroethane,
trichloroethylene and tetrachloroethylene have been exclusively
used. Such chlorine series organic solvents have no inflammability,
are easy in handling and high in stability. However, they are
highly toxic to the human body, which not only raises a problem
with regard to hygiene, but also are unfavorable from the viewpoint
of working environment.
[0003] For solving such a problem of the conventional
photosensitive resin compositions, water-soluble photosensitive
resin compositions containing polyvinyl alcohol or water-soluble
nylon as a resin component have been proposed. However, they are
low in impact resilience, so that they are unsuitable as materials
for printing plates for printing thick printing materials such as
corrugated fiberboards. Moreover, they have the disadvantage that
water-color ink can not be used. Then, the present inventors have
proposed a photosensitive resin composition comprising a resin
obtained by reacting a carboxyl group-containing polymer having an
acid value of 30 mg KOH/g or more and a glass transition
temperature of 30.degree. C. or more, a compound having two
isocyanate groups in one molecule and a compound having two
hydroxyl groups in one molecule as indispensable components, a
photopolymerizable unsaturated monomer, and a photopolymerization
initiator, as a photopolymerization initiator-containing
photosensitive resin composition having water developing properties
and excellent in impact resilience, in JP-A-8-36263 (the term
"JP-A" as used herein means an "unexamined published Japanese
patent publication"). The above-mentioned photosensitive resin
composition has water developing properties and are excellent in
impact resilience. However, it has the problems that a hardened
portion forming a line pattern portion of a printing plate material
is poor in water resistance, that the ink resistance is low, and
moreover that the press life is also poor.
[0004] However, the photosensitive resin composition described in
JP-A-8-36263 has excellent characteristics of water developing
properties and high impact resilience which no conventional
photosensitive resins have. Accordingly, based on the idea that an
excellent photosensitive resin composition will be obtained by
modifying the above-mentioned photosensitive resin composition
described in JP-A-8-36263, the present inventors have made
intensive studies. As a result, the inventors have discovered that
a resin obtained by reacting a carboxyl group-containing polymer
which has an acid value of 30 mg KOH/g or more and a glass
transition temperature of 30.degree. C. or more, a compound having
two isocyanate groups in one molecule, a compound having two
hydroxyl groups in one molecule and a photopolymerizable
unsaturated monomer having one hydroxyl group in one molecule is
effective as the resin component of the photosensitive resin
composition, thus completing the present invention.
[0005] It is therefore an object of the present invention to
provide a photosensitive resin composition having water developing
properties and high sensitivity.
[0006] Furthermore, another object of the present invention is to
provide a resin plate for flexography which has excellent impact
resilience and is excellent in water resistance, ink resistance and
press life of the line pattern area.
DISCLOSURE OF THE INVENTION
[0007] The invention which achieves the above objects is described
below as items (1) to (11).
[0008] (1) A photosensitive resin composition comprising an
urethane resin obtained by reacting (A) a carboxyl group-containing
polymer having an acid value of 30 mg KOH/g or more and a glass
transition temperature of 30.degree. C. or more, (B) a compound
having two isocyanate groups in one molecule, (C) a compound having
two hydroxyl groups in one molecule and (D) a photopolymerizable
unsaturated monomer having one hydroxyl group in one molecule, and
a photopolymerization initiator.
[0009] (2) A photosensitive resin composition comprising an
urethane resin obtained by reacting (A) a carboxyl group-containing
polymer having an acid value of 30 mg KOH/g or more and a glass
transition temperature of 30.degree. C. or more, (B) a compound
having two isocyanate groups in one molecule, (C) a compound having
two hydroxyl groups in one molecule and (D) a photopolymerizable
unsaturated monomer having one hydroxyl group in one molecule, and
a photopolymerizable unsaturated monomer and a photopolymerization
initiator.
[0010] (3) A photosensitive resin composition comprising an
urethane resin comprising as structural units (A) a carboxyl
group-containing polymer having an acid value of 30 mg KOH/g or
more and a glass transition temperature of 30.degree. C. or more,
(B) a compound having two isocyanate groups in one molecule, (C) a
compound having two hydroxyl groups in one molecule and (D) a
photopolymerizable unsaturated monomer having one hydroxyl group in
one molecule, and a photopolymerization initiator.
[0011] (4) The photosensitive resin composition according to any
one of the above items (1) to (3), wherein the urethane resin is a
resin obtained by reacting component (B), component (C), component
(D) and component (A) in this order.
[0012] (5) The photosensitive resin composition according to any
one of the above items (1) to (4), wherein component (A) is an
acrylic polymer.
[0013] (6) The photosensitive resin composition according to any
one of the above items (1) to (4), wherein component (B) is
hexamethylene diisocyanate.
[0014] (7) The photosensitive resin composition according to any
one of the above items (1) to (5), wherein component (C)is
polyether diol.
[0015] (8) The photosensitive resin composition according to any
one of the above items (1) to (4), wherein component (D) is a
hydroxyl group-containing unsaturated acrylic acid ester series
monomer.
[0016] (9) The photosensitive resin composition according to the
above item (8), wherein the hydroxyl group-containing unsaturated
acrylic acid ester series monomer is 2-hydroxyethyl acrylate.
[0017] (10) A resin plate for flexography using the photosensitive
resin composition of any one of the above items (1) to (9).
[0018] (11) A resin plate for flexography, which uses the
photosensitive resin composition of any one of the above items (1)
to (9) and has a photosensitive resin layer having an impact
resilience of 30% or more according to JIS K6301-11.
BEST MODE TO CARRY OUT THE INVENTION
[0019] The present invention will be described below in detail.
[0020] There is no particular limitation on component (A) used in
the photosensitive resin composition of the present invention, as
long as it is a carboxyl group-containing polymer having an acid
value of 30 mg KOH/g or more and a glass transition temperature of
30.degree. C. or more. There is also no particular limitation on a
method for producing it, and it can be produced by any known
method. Examples thereof include a method of copolymerizing a
carboxyl group-containing monomer with an unsaturated monomer.
Specific examples of the above-mentioned carboxyl group-containing
monomers include acrylic acid, methacrylic acid, maleic acid,
maleic monoester, fumaric acid, fumaric monoester, itaconic acid,
itaconic monoester and cinnamic acid. The above-mentioned carboxyl
group-containing monomers may be used either alone or as a
combination of two or more of them.
[0021] The unsaturated monomers to be copolymerized with the
above-mentioned carboxyl group-containing monomers include
methacrylate monomers, aromatic vinyl monomers and other vinyl
monomers copolymerizable with these monomers. The above-mentioned
unsaturated monomers are suitably used because the use. thereof
elevates the glass transition temperature of component (A) to
30.degree. C. or more. In particular, the use of the methacrylate
monomers or the aromatic vinyl monomers alone is preferred, since a
printing resin plate having high impact resilience can be obtained.
Among them, the use of an acrylic polymer is preferred since the
printing resin plate having high transparency as well as high
impact resilience can be obtained. Specific examples of the
above-mentioned methacrylate monomers include alkyl methacrylates
such as methyl methacrylate, ethyl methacrylate, propyl
methacrylate, isopropyl methacrylate, butyl methacrylate,
cyclohexyl methacrylate, 2-ethylhexyl methacrylate, n-octyl
methacrylate, dodecyl methacrylate and stearyl-methacrylate; aryl
methacrylates such as benzyl methacrylate; methacrylic acid
substituent group-containing alkyl esters such as glycidyl
methacrylate and methacrylic 2-amino esters; methacrylic acid
derivatives such as methoxyethyl methacrylate and ethylene oxide
adducts of methacrylic acid; fluorine-containing methacrylates such
as perfluoromethyl methacrylate, perfluoroethyl methacrylate,
perfluoropropyl methacrylate, perfluorobutyl methacrylate,
perfluorooctyl methacrylate, 2-perfluoroethylethyl methacrylate,
2-perfluoromethyl-2-per- fluoroethylmethyl methacrylate,
triperfluoromethylmethyl methacrylate,
2-perfluoroethyl-2-perfluorobutylethyl methacrylate,
2-perfluorohexylethyl methacrylate, 2-perfluorodecylethyl
methacrylate and 2-perfluorohexadecylethyl methacrylate, and
hydroxyl group-containing addition polymerizable monomers such as
2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate,
3-hydroxypropyl methacrylate, polyethylene glycol monomethacrylate,
polypropylene glycol monomethacrylate and polycaprolactone-modified
products of 2-hydroxyethyl methacrylate (trade name: Placcel F
series, manufactured by Daicel Chemical Industries Ltd.). The
above-mentioned methacrylate monomers may be used either alone or
as a combination of two or more of them.
[0022] Further, there is no particular limitation on the aromatic
vinyl monomers, and known aromatic vinyl monomers can be used.
Specific examples thereof include styrene, .alpha.-methylstyrene,
o-methylstyrene, m-methylstyrene, p-methylstyrene, chlorostyrene,
styrenesulfonic acid and sodium styrenesulfonate. The
above-mentioned aromatic vinyl monomers may be used either alone or
as a combination of two or more of them.
[0023] In addition to the above-mentioned methacrylate monomers and
aromatic vinyl monomers, the other vinyl monomers copolymerizable
with the carboxyl group-containing monomers can also be used.
Specifically, the other vinyl monomers include acrylic acid series
monomers such as methyl acrylate, ethyl acrylate, n-butyl acrylate
and 2-ethylhexyl acrylate; hydroxyl group-containing addition
polymerizable monomers such as 2-hydroxyethyl acrylate,
2-hydroxypropyl acrylate, 3-hydroxypropyl acrylate, polyethylene
glycol monoacrylate, polypropylene glycol monoacrylate and
polycaprolactone-modified products of 2-hydroxyethyl acrylate
(trade name: Placcel F series, manufactured by Daicel Chemical
Industries Ltd.); hydroxyl group-containing addition polymerizable
monomers such as (meth)allyl alcohol 4-hydroxymethylstyrene; maleic
anhydride and dialkyl maleates; dialkyl fumarates;
fluorine-containing vinyl monomers such as perfluoroethylene,
perfluoropropylene and vinylidene fluoride; vinylalkyloxysilyl
group-containing monomers such as vinyltrimethoxysilane and
vinyltriethoxysilane; maleimide derivatives such as maleimide,
methylmaleimide, ethylmaleimide, propylmaleimide, butylmaleimide,
octylmaleimide, dodecylmaleimide, stearylmaleimide, phenylmaleimide
and cyclohexylmaleimide; nitryl group-containing vinyl monomers
such as acrylonitrile and methacrylonitrile; amido group-containing
vinyl monomers such as acrylamide and methacrylamide; vinyl esters
such as vinyl acetate, vinyl propionate, vinyl pivalate, vinyl
benzoate and vinyl cinnamate; alkenes such as ethylene and
propylene; dienes such as butadiene and isoprene; and vinyl
chloride, vinylidene chloride and acrylchlorides. The
above-mentioned other vinyl monomers can be used either alone or as
a combination of two or more of them.
[0024] Further, component (A) is required to have an acid value of
30 mg KOH/g or more, 80 mg KOH/g or more, preferably 90 mg KOH/g or
more, more preferably 100 mg KOH/g or more, most preferably 120 mg
KOH/g or more, and 300 mg KOH/g or less. For giving such an acid
value, acidic functional group-containing acidic monomers can also
be used, as well as the above-mentioned carboxyl group-containing
monomers. The above-mentioned acidic monomers include, for example,
styrenesulfonic acid, 2-acrylamido-2-methylpropane-sulfonic acid,
2-methacrylamido-2-meth- ylpropanesulfonic acid, 2-sulfoethyl
methacrylate, 2-sulfoethyl acrylate, vinyl-sulfonic acid,
acrylsulfonic acid and methacrylsulfonic acid. The above-mentioned
acidic monomers may be used either alone or as a combination of two
or more of them.
[0025] Component (A) used in the present invention can be produced
by polymerizing the above-mentioned respective components by known
polymerization methods such as radical polymerization, anionic
polymerization and cationic -polymerization. In particular, when
the methacrylate monomers or the aromatic vinyl monomers are used
as the unsaturated monomers to be copolymerized with the carboxyl
group-containing monomers, radical polymerization or anionic
polymerization is suitably employed. There is no particular
limitation on radical polymerization initiators used in the
above-mentioned radical polymerization, and examples of the radical
polymerization initiator include organic peroxides such as isobutyl
peroxide, cumyl peroxy-neodecanoate, diisopropyl oxydicarbonate,
di(n-propyl) peroxydicarbonate, di(2-ethoxyethyl)
peroxydicarbonate, di(2-ethylhexyl) peroxydicarbonate, t-hexyl
peroxyneodecanoate, t-butyl peroxyneodecanoate, t-hexyl
peroxypivalate, t-butyl peroxypivalate, 3,5,5-trimethylhexanoyl
peroxide, decanoyl peroxide, lauroyl peroxide, cumyl peroxyoctate,
succinic acid peroxide, acetyl peroxide, t-butyl
peroxy(2-ethylhexanate), m-toluoyl peroxide, benzoyl peroxide,
t-butyl peroxy-isobutylate, 1,1-bis(t-butylperoxy)cyclohexane,
t-butyl peroxymaleate, t-butyl peroxylaurate, cyclohexanone
peroxide, t-butyl peroxyisopropylcarbonate,
2,5-dimethyl-2,5-di(benzoylperoxyhexane), t-butyl peroxyacetate,
2,2-bis(t-butylperoxy)butane, t-butyl peroxybenzoate, n-butyl
4,4-bis(t-butylperoxy)valerate, di-t-butyl peroxyisophthalate,
methyl ethyl ketone peroxide, dicumyl peroxide,
2,5-dimethyl-2,5-di(t-butylperoxy)hexane,
.alpha.,.alpha.'-bis(t-butylper- oxy-m-isopropyl)benzene,
t-butylcumyl peroxide, diisobutylbenzene hydroperoxide, di-t-butyl
peroxide, p-menthane hydroperoxide,
2,5-dimethyl-2,5-di(t-butylperoxy)hexyne-3,1,1,3,3-tetramethylbutyl
hydroperoxide, cumene hydroperoxide and t-butyl hydroperoxide;
inorganic peroxides such as hydrogen peroxide, potassium
persulfate, sodium persulfate and ammonium persulfate; azo
compounds such as 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile),
2,2'-azobis(2-cyclo-pro- pylpropionitrile),
2,2'-azobis(2,4-dimethylvaleronitrile),
2,2'-azobisisobutylonitrile, 2,2'-azobis(2-methylbutylonitrile),
1,1'-azobis(cyclohexane-1-carbonitrile),
2-(carbamoylazo)isobutylonitrile- ,
2-phenylazo-4-methoxy-2,4-dimethylvaleronitrile,
2,2'-azobis(2-amidinopr- opane) dihydrochloride,
2,2'-azobis(N,N'-dimethyleneisobutylamidine),
2,2'-azobis[2-methyl-N-(2-hydroxyethyl)propionamide],
2,2'-azobis(isobutylamide) dihydrate, 4,4'-azobis(4-cyanopentanoic
acid) and 2,2'-azobis(2-cyanopropanol); redox initiators such as
hydrogen peroxide-Fe(II) salt, persulfate-sodium hydrogensulfite,
cumene hydroperoxide-Fe(II) salt and benzoyl
peroxide-dimethylaniline; and photosensitizers such as diacetyl,
dibenzyl and acetophenone.
[0026] Examples of the polymerization methods include bulk
polymerization, solution polymerization, suspension polymerization,
emulsion polymerization and solid-phase polymerization. The
monomer(s) as starting material(s) and the radical polymerization
initiator may be placed together in a polymerization vessel, or
polymerization may be conducted while supplying the respective
components to the polymerization vessel at any time. Further,
polymerization maybe performed by a method of supplying the
monomer(s) as starting material(s) and the radical polymerization
initiator to the polymerization vessel, after a part of the solvent
has previously been placed in the polymerization vessel.
[0027] Component (A) obtained by polymerizing the above-mentioned
respective components is required to have a glass transition
temperature of 30.degree. C. or more, preferably from 60 to
180.degree. C., more preferably 90.degree. C. or more, most
preferably from 100 to 150.degree. C. If the glass transition
temperature is lower than 30.degree. C., the proportion of the hard
segment portions of the resin is reduced, resulting in poor impact
resilience.
[0028] As Component (A) of the present invention, an acrylic block
polymer comprising two or more of block structures of hard segments
and soft segments also can be preferably used. In this case, the
above-described preferred range of the glass transition temperature
is applicable. Specifically, it is preferred to use a block polymer
in which the block structure attributable to the soft segment has a
Tg of 30.degree. C. or more from the standpoint of retaining the
balance between the impact resilience and other physical
properties. In this case, the hard segment preferably has a Tg of
30.degree. C. or more, more preferably 60.degree. C. or more, and
most preferably 90.degree. C. or more. The upper limit of the Tg is
150.degree. C. The number average molecular weight of component (A)
ranges generally from 1,000 to 150,000, preferably from 2,000 to
50,000, and more preferably from 10,000 to 30,000. If the number
average molecular weight is less than 1,000, the proportion of
water-soluble and alkali-soluble portions of the resin is reduced
to deteriorate water developing properties, and the proportion of
the hard segment portions of the resin is also reduced, resulting
in poor impact resilience. On the other hand, if the number average
molecular weight exceeds 150,000, the proportion of the hard
segment portions of the resin becomes too large, resulting in poor
impact resilience.
[0029] There is no particular limitation on component (B) used in
the present invention, as long as it is an isocyanate compound.
Specific examples thereof include aliphatic, alicyclic and aromatic
diisocyanate compounds such as dimethylene diisocyanate,
trimethylene diisocyanate, tetramethylene diisocyanate,
pentamethylene diisocyanate, hexamethylene diisocyanate,
heptamethylene diisocyanate, 2,2-dimethylpentane-1,5-diisoc-
yanate, octamethylene diisocyanate,
2,5-dimethylhexane-1,6-diisocyanate,
2,2,4-trimethylpentane-1,5-diisocyanate, nonamethylenediisocyanate,
2,2,4-trimethylhexanediisocyanate, decamethylene diisocyanate,
isophorone diisocyanate, 1,4-phenylene diisocyanate,
4,4-diisocyanate-3,3-dimethylph- enyl,
diphenyldimethane-4,4'-diisocyanate, tolylene diisocyanate,
4,4'-diphenylmethane diisocyanate and naphthalene-1,5-diisocyanate;
and oligomers and polymers thereof. They can be used either alone
or as a combination of two or more of them. Hexamethylene
diisocyanate is preferable among others, because it gives
photo-hardenability excellent in flexibility, impact resilience and
press life.
[0030] There is no particular limitation on component (C) used in
the present invention, as long as it has two hydroxyl groups in one
molecule. However, it is preferable to have a hydrophilic group
because water developing properties are improved. Specifically, the
compounds used as component (C) include aliphatic diols such as
ethylene glycol, diethylene glycol, triethylene glycol, propylene
glycol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol,
1,5-heptanediol, 1,6-hexanediol, trimethylene glycol, dipropylene
glycol, tripropylene glycol, neopentyl glycol,
2-methyl-2,4-pentanediol, 2-ethyl-1,3-hexanediol,
3-methyl-1,5-pentanediol and 1,8-octanediol; alicyclic diols such
as cyclohexane-1,4-diol, 1,4-cyclohexane glycol and hydrogenated
bisphenol A; aromatic diols such as xylylene glycol,
1,4-dihydroxyethyl benzene and ethylene oxide adducts of bisphenol
A; sulfur atom-containing diols such as dithiodiethanol and
thiodiethylene glycol; and oligomers and polymers thereof. Specific
examples of the oligomers and polymers include polyether diols such
as polyethylene glycol, polypropylene glycol, block polymers of
polyethylene glycol and polypropylene glycol and polybutylene
glycol; polyolefin diols such as Poltherm manufactured by
Mitsubishi Chemical Corporation, hydrogenated polyisoprene having
hydroxyl groups at both ends manufactured by Kuraray Co., Ltd. and
Epol manufactured by Idemitsu Petrochemical Co., Ltd.;
polybutadiene diols such as OH group-terminated HTBN manufactured
by B. F. Goodrich Co.; polyester diols such as Kuraball
manufactured by Kuraray Co., Ltd.; polycarbonate diols;
polyurethane diols, polyorganosiloxane diols; and polyacrylic diols
such as acrylic polymers having hydroxyl groups at both ends
described in JP-A-5-262808. The polyether diols are suitable among
others because they are excellent in flexibility and impact
resilience. The above-mentioned compounds used as component (C) may
be used either alone or as a combination of two or more of
them.
[0031] The compound to be used as component (D) in the present
invention is not limited as long as it is a photopolymerizable
unsaturated monomer having one hydroxyl group in one molecule.
Examples thereof include hydroxyl group-containing addition
polymerizable monomers such as 2-hydroxyethyl (meth)acrylate,
2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) adrylate,
methyl 2-hydroxymethylacrylate, 4-hydroxybutyl (meth)acrylate,
polyethylene glycol mono(meth)acrylate, polypropylene glycol
mono(meth)acrylate, polycaprolactone-modified products of
2-hydroxyethyl (meth)acrylate (trade name: Placcel F series,
manufactured by Daicel Chemical Industries Ltd.) and (meth)acrylic
alcohol 4-hydroxymethylstyrene. The above-mentioned compounds used
as component (D) may be used either alone or as a combination of
two or more of them. 2-Hydroxyethyl acrylate is preferable among
others because it is excellent in sensitivity.
[0032] Thus, the use of the photopolymerizable unsaturated monomer
having one hydroxyl group in one molecule results in an urethane
resin having a photopolymerizable double bond introduced into the
structural port-ion formed by the reaction of components (B) and
(C). Namely, component (D) reacts at least with the structural
portion formed by the reaction of components (B) and (C), so that a
photopolymerizable double bond is introduced into the structural
portion to provide a good urethane resin.
[0033] The urethane resin used in the present invention is a resin
having structural units obtained by the above-mentioned respective
components (A) to (D). Preferably, component (D) is reacted with a
product obtained by reacting component (B) with component (C), and
then, component (A) is reacted with the resulting product, thereby
obtaining the urethane resin. The use of this urethane resin
provides a photosensitive resin composition excellent in ink
resistance and press life. The compounding ratio of component (B)
to component (C) is generally from 1.1 to 10.0, preferably from 1.1
to 5.0, and more preferably from 1.2 to 2.5, in the equivalent
ratio of the NCO group of component (B) to the hydroxyl group of
component (C) (NCO group/hydroxyl group). The compound obtained by
the above-mentioned reaction generally has a glass transition
temperature of 0.degree. C. or less, preferably -30.degree. C. or
less, more preferably -50.degree. C., and is preferably
water-soluble or hydrophilic. Catalysts may be used in the
above-mentioned reaction. The catalysts include di-n-butyltin
dilaurate, stannous octate, triethylenediamine, diethylenediamine,
triethylamine, metal naphthenates and metal octylates such as lead
octylate. Further, solvents may be used, and examples thereof
include ketones such as acetone, methyl ethyl ketone, methyl
isobutyl ketone and cyclohexanone; aromatic hydrocarbons such as
toluene and xylene; hydrocarbon halides such as chlorobenzene,
trichlene and perchlene; ethers such as tetrahydrofuran and
dioxane; and esters such as cellosolve acetate, ethyl acetate and
butyl acetate.
[0034] The compounding ratio of component (D) to the [(B)+(C)]
product is preferably 0.25 to 1.95 mol of component (D) per mol of
[(B)+(C)] product. Further, the ratio of the [(B)+(C)+(D)] product
to component (A) is preferably 30 to 250 parts by weight per 100
parts by weight of component (A). The obtained urethane resin can
be incorporated into the photosensitive resin composition of the
present invention in an amount of from 40 to 99.9% by weight.
[0035] The photosensitive resin compositions further contain
photopolymerization initiators. Specifically, the above-mentioned
photopolymerization initiators include 1-hydroxycyclohexyl phenyl
ketone, 2,2-dimethoxy-1,2-diphenylethane-1-one,
2-methyl-1-[4-(methylthio)phenyl]- -2-morpholinopropane-1-one,
2-benzyl-2-dimethylamino-1-(4-morpholinophenyl- )-butane-1-one,
2-hydroxy-2-methyl-1-phenylpropane-1-one,
2,4,6-trimethylbenzoyldiphenylphosphine oxide,
1-[4-(2-hydroxyethoxy)phen- yl]-2-hydroxy-2-methyl-1-propane-1-one,
2,4-diethylthioxanthone, 2-chlorothioxanthone,
2,4-dimethylthioxanthone, 3,3-dimethyl-4-methoxyben- zophenone,
benzophenone, 1-chloro-4-propoxythioxanthone,
1-(4-isopropyl-phenyl)-2-hydroxy-2-methylpropane-1-one,
1-(4-dodecylphenyl)-2-hydroxy-2-methylpropane-1-one,
4-benzoyl-4'-methyl dimethylsulfide, 4-dimethylaminobenzoic acid,
methyl 4-dimethylaminobenzoate, ethyl 4-dimethylaminobenzoate,
butyl 4-dimethylaminobenzoate, 2-ethylhexyl
4-dimethylamino-benzoate, 2-isoamyl 4-dimethylaminobenzoate,
2,2-diethoxy-acetophenone, benzyl dimethyl ketal,
benzyl-.beta.-methoxyethyl acetal, 1-phenyl-1,2-propanedione-2-(o--
ethoxycarbonyl)oxime, methyl o-benzoylbenzoate,
bis(4-dimethylaminophenyl)- ketone,
4,4'-bisdiethylaminobenzophenone, 4,4'-dichlorobenzophenone,
benzyl, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin
isopropyl ether, benzoin n-butyl ether, benzoin isobutyl ether,
p-dimethylaminoacetophenone, p-tert-butyl-trichloroacetophenone,
p-tert-butyl dichloroacetophenone, thioxanthone,
2-methylthioxanthone, 2-isopropylthioxanthone, dibenzosuberone,
.alpha.,.alpha.-dichloro-4-phen- oxyacetophenone and pentyl
4-dimethylaminobenzoate. The above-mentioned photopolymerization
initiators can be used either alone or as a mixture of two or more
of them. The above-mentioned photopolymerization initiator can be
used in a conventionally added amount, but is generally used in an
amount of 0.1 to 10% by weight based on the photosensitive resin
composition.
[0036] For preventing film reduction and swelling in developing, it
is preferred that the photosensitive resin compositions of the
present invention contain photopolymerizable unsaturated monomers.
The above-mentioned photopolymerizable unsaturated monomers include
acrylic acid and salts thereof; alkyl (meth)acrylates such as
methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate,
isopropyl (meth)-acrylate, butyl (meth)acrylate, cyclohexyl
(meth)acrylate, 2-ethylhexyl (meth)acrylate, n-octyl
(meth)acrylate, dodecyl (meth) acrylate and stearyl (meth)
acrylate; aryl (meth)-acrylates such as benzyl (meth)acrylate;
(meth)acrylic acid substituent group-containing alkyl esters such
as glycidyl (meth) acrylate and (meth)acrylic 2-amino esters;
(meth)-acrylic acid derivatives such as methoxyethyl (meth)acrylate
and ethylene oxide adducts of (meth) acrylic acid;
fluorine-containing (meth)acrylates such as perfluoromethyl
(meth)-acrylate, perfluoroethyl (meth) acrylate, perfluoropropyl
(meth) acrylate, perfluorobutyl (meth)acrylate, perfluorooctyl
(meth)acrylate, 2-perfluoromethylmethyl (meth)acrylate,
2-perfluoromethyl-2-perfluoroethy- lmethyl (meth)acrylate,
triperfluoromethylmethyl (meth)acrylate, 2-trifluoromethyl-ethyl
(meth)acrylate, diperfluoromethylmethyl (meth)acrylate,
2-perfluoroethylethyl (meth)acrylate,
2-perfluoroethyl-2-perfluorobutylethyl (meth)acrylate,
2-perfluoromethyl-2-perfluoroethylethyl (meth)acrylate,
2-perfluoroethyl-2-perfluorobutylethyl (meth)acrylate,
2-perfluorohexylethyl (meth)acrylate, 2-perfluorodecylethyl
(meth)acrylate and 2-perfluorohexadecylethyl (meth)acrylate;
silicon-containing (meth)acrylate monomers such as
.gamma.-(methacryloyloxypropyl)trimethoxysilane; maleic anhydride,
maleic acid, salts of maleic acid, and monoalkyl esters and dialkyl
esters of maleic acid; fumaric acid, and monoalkyl esters and
dialkyl esters of fumaric acid; itaconic acid, and monoalkyl esters
and dialkyl esters of itaconic acid; hydroxyl group-containing
addition polymerizable monomers such as 2-hydroxyethyl
(meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl
(meth)-acrylate, methyl 2-hydroxymethylacrylate, tetramethylene
glycol (meth)acrylate, polyethylene glycol mono(meth)-acrylate,
polypropylene glycol mono(meth)acrylate, polycaprolactone-modified
products of 2-hydroxyethyl (meth)acrylate (trade name: Placcel F
series, manufactured by Daicel Chemical Industries Ltd.) and
(meth)acrylic alcohol 4-hydroxymethylstyrene; aromatic vinyl
monomers such as styrene, .alpha.-methylstyrene, o-methylstyrene,
m-methylstyrene, p-methylstyrene, chlorostyrene, styrenesulfonic
acid and sodium styrenesulfonate; maleimide derivatives such as
maleimide, methylmaleimide, ethylmaleimide, propylmaleimide,
butyl-maleimide, octylmaleimide, dodecylmaleimide,
stearyl-maleimide, phenylmaleimide and cyclohexylmaleimide;
nitrile-group containing vinyl monomers such as acrylonitrile and
methacrylonitrile; amido group-containing vinyl monomers such as
acrylamide, methacrylamide, methylenebis(meth)acrylamide- ,
methylenebis(meth)acrylamide,
1,6-hexamethylenebis(meth)-acrylamide,
diethylenetriaminetris(meth)acrylamide,
N-(hydroxymethyl)(meth)acrylamide and
N,N'-bis(.beta.-hydroxyethyl)-(meth)acrylamide; and
phenoxypolyethylene glycol (meth)-acrylate, ethylene glycol
di(meth)acrylate, diethylene glycol di(meth)acrylate, diallyl
itaconate, glycerol di(meth)-acrylate, glycerol tri(meth)acrylate,
trimethylolpropane tri(meth) acrylate, pentaerythritol tri(meth)
acrylate, glycerol polypropylene glycol tri(meth)acrylate,
1,3-propylene glycol di(meth)acrylate, 1,4-cyclohexanediol
di(meth)acrylate, 1,2,4-butanetriol tri(meth)acrylate, glycerol
polypropyreneglycol tri(meth)acrylate, 1,4-benzenediol
di(meth)acrylate, pentaerythritol tetra(meth)-acrylate,
tetramethylene glycol di(meth)acrylate, 1,5-pentanediol
di(meth)acrylate, 1,6-hexanediol di(meth)-acrylate, divinyl
adipate, divinyl phthalate and acrylated or methacrylated urethane.
The above-mentioned photopolymerizable unsaturated monomers can be
used either alone or as a combination of two or more of them.
[0037] Water-soluble monomers and crosslinkable monomers are
preferred among others. Examples of the above-mentioned
water-soluble monomers include (meth)acrylic acid and salts
thereof, polyethylene glycol mono(meth)acrylate, methyl
2-hydroxymethylacrylate, ethyl 2-hydroxymethylacrylate, butyl
2-hydroxymethylacrylate, and maleic acid and salts thereof. There
is no particular limitation on the crosslinkable monomers, as long
as they are monomers each having two or more double bonds in one
molecule. The above-described photopolymerizable unsaturated
monomer can be added in an amount of 0 to 50% by weight based on
the photosensitive resin composition.
[0038] Further, the photosensitive resin compositions of the
present invention can also contain dyes, pigments, polymerization
inhibitors, antioxidants and photodeterioration inhibitors to
improve their performance as needed.
[0039] The photosensitive resin compositions of the present
invention can be dissolved in an organic solvent by known methods,
together with various additional components, as needed, and formed
in a film or tabular form, followed by removal of the solvent.
Alternatively, the composition may be mixed by use of roll mixers,
and then formed in a film or tabular form with hot presses, thereby
forming a photosensitive resin layer for producing a flexo relief.
For preventing desensitization or adhesion caused by atmospheric
oxygen, surface of the photosensitive resin layer for producing a
flexo relief is preferably coated with a water-soluble or
alcohol-soluble resin comprising polyvinyl alcohol, cellulose
derivatives, polyamides or polyimides in a thickness of 1 to 50
.mu.m to form a coating.
[0040] The photosensitive resin layer obtaind above is pressed on a
film or sheet of a resin such as polyethylene terephthalate
(hereinafter referred to as PET), polyethylene and polypropylene,
or a plate composed of a metal such as iron, aluminum and copper,
and previously exposed, if necessary. Then, the photosensitive
resin layer is selectively irradiated with actinic rays through a
negative mask to conduct image exposure, and the unexposed areas
are washed out with a developing solution, followed by drying to
produce a flexo plate for flexography having rubber elasticity. The
above-mentioned image exposure is carried out by irradiation with a
light source such as extra-high pressure mercury lamp and chemical
lamp for about 2 to about 20 minutes. After exposure, development
is executed. Examples of the developing solution include water;
hydroxides of alkali metals such as lithium, sodium and potassium;
carbonates; bicarbonates; phosphates; pyrophosphates; primary
amines such as benzylamine and butylamine; secondary amines such as
dimethylamine, dibenzylamine and diethanolamine; tertiary amines
such as trimethylamine, triethylamine and triethanolamine; cyclic
amines such as morpholine, piperazine and pyridine; polyamines such
as ethylenediamine and hexamethylenediamine; ammonium hydroxides
such as tetraethylammonium hydroxide, trimethylbenzylammonium
hydroxide and trimethylphenylbenzyl-am- monium hydroxide, sulfonium
hydroxides such as trimethyl-sulfonium hydroxide,
diethylmethylsulfonium hydroxide and dimethylbenzylsulfonium
hydroxide; and diluted aqueous solutions of corrin. The unexposed
areas are removed by the above-mentioned development, and only
exposed areas remain. As the developing methods with the developing
solution, conventional methods such as brush development and spray
development can be used.
[0041] The flexographic resin plate prepared by using the
photosensitive resin composition has a photosensitive resin layer
excellent water-developability and impact resilience. The
sensitivity of the resin layer is rated as "good", when the resin
layer has a value of 9 or more in terms of the number of the
hardening steps of 21 step tablet manufactured by Kodak when light
having a wavelength falling within the range of 300 to 400 nm is
irradiated at 2000 mJ/cm.sup.2. The resin layer preferably has a
value of 11 or more, more preferably 13 or more, most preferably 14
or more. With respect to the impact resilience (as measured by a
JIS impact resilience testing machine) which the resin layer of the
resin plate of flexographic printing preferably has, the impact
resilience of the resin layer is rated as "good", when the resin
layer has an impact resilience of 30% or more. The resin layer
preferably has an impact resilience of 32% or more, more preferably
34% or more, still preferably 40% or more, and most preferably 45%
or more.
EXAMPLES
[0042] The present invention will be further illustrated in greater
detail with reference to the following examples and comparative
examples, which are, however, not to be construed as limiting the
invention. The number average molecular weight used in the examples
and comparative examples was determined from a calibration curve
according to standard polystyrene by gel permeation chromatography
(GPC).
Production Example 1
[0043] In a four-neck flask equipped with a stirrer, a thermometer,
a condenser, a dropping funnel and a nitrogen gas-introducing pipe,
100 parts by weight of methyl ethyl ketone was placed, and the
temperature thereof was raised to 75.degree. C. Then, 2.5 parts by
weight of a methyl ethyl ketone solution containing 20 wt % of
azobis-2-methylbutyronitrile was poured thereinto while blowing
nitrogen gas therein. Subsequently, a previously prepared monomer
mixture consisting of 5.1 parts by weight of acrylic acid, 54.8
parts by weight of methyl methacrylate and 40.1 parts by weight of
ethyl acrylate was added dropwise for 2 hours. The temperature in
the flask during dropping was maintained at the reflux temperature
of methyl ethyl ketone. After termination of dropping, the
temperature was maintained at the same temperature for 2 hours.
Then, 5 parts by weight of a methyl ethyl ketone solution
containing 20 wt % of azobis-2-methylbutyronitrile was poured
thereinto, and the resulting solution was stirred for 2 hours.
Thus, the reaction was terminated, and then, the solution was
cooled to obtain acrylic polymer A having a number average
molecular weight of 49,000, an acid value of 39 mg KOH/g and a
glass transition temperature of 38.degree. C.
Production Example 2
[0044] In a four-neck flask equipped with a stirrer, a thermometer,
a condenser, a dropping funnel and a nitrogen gas-introducing pipe,
100 parts by weight of methyl ethyl ketone was placed, and the
temperature thereof was raised to 75.degree. C. Then, 6.25 parts by
weight of a methyl ethyl ketone solution containing 20 wt % of
azobis-2-methylbutyronitrile was poured thereinto while blowing
nitrogen gas therein. Subsequently, a previously prepared monomer
mixture consisting of 11.5 parts by weight of acrylic acid, 62.4
parts by weight of methyl methacrylate and 26.1 parts by weight of
ethyl acrylate was added dropwise for 2 hours. The temperature in
the flask during dropping was maintained at the reflux temperature
of methyl ethyl ketone. After termination of dropping, the
temperature was maintained at the same temperature for 2 hours.
Then, 5 parts by weight of a methyl ethyl ketone solution
containing 20 wt % of azobis-2-methylbutyronitrile was poured
thereinto, and the resulting solution was stirred for 2 hours.
Thus, the reaction was terminated, and then, the solution was
cooled to obtain acrylic polymer B having a number average
molecular weight of 18,000, an acid value of 90 mg KOH/g and a
glass transition temperature of 63.degree. C.
Production Example 3
[0045] In a four-neck flask equipped with a stirrer, a thermometer,
a condenser, a dropping funnel and a nitrogen gas-introducing pipe,
100 parts by weight of methyl ethyl ketone was placed, and the
temperature thereof was raised to 75.degree. C. Then, 1 part by
weight of a methyl ethyl ketone solution containing 20 wt % of
azobis-2-methylbutyronitrile was poured thereinto while blowing
nitrogen gas therein. Subsequently, a previously prepared monomer
mixture consisting of 13.5 parts by weight of acrylic acid, 83.8
parts by weight of methyl methacrylate and 2.7 parts by weight of
ethyl acrylate was added dropwise for 2 hours. The temperature in
the flask during dropping was maintained at the reflux temperature
of methyl ethyl ketone. After termination of dropping, the
temperature was maintained at the same temperature for 2 hours.
Then, 5 parts by weight of a methyl ethyl ketone solution
containing 20 wt % of azobis-2-methylbutyronitrile was poured
thereinto, and the resulting solution was stirred for 2 hours.
Thus, the reaction was terminated, and then, the solution was
cooled to obtain acrylic polymer C having a number average
molecular weight of 25,000, an acid value of 105 mg KOH/g and a
glass transition temperature of 100.degree. C.
Production Example 4
[0046] In a four-neck flask equipped with a stirrer, a thermometer,
a condenser, a dropping funnel and a nitrogen gas-introducing pipe,
100 parts by weight of methyl ethyl ketone was placed, and the
temperature thereof was raised to 75.degree. C. Then, 1 part by
weigh of a methyl ethyl ketone solution containing 20 wt % of
azobis-2-methylbutyronitrile was poured thereinto while blowing
nitrogen gas therein. Subsequently, a previously prepared monomer
mixture consisting of 11.5 parts by weight of acrylic acid, 62.4
parts by weight of methyl methacrylate and 26.1 parts by weight of
ethyl acrylate was added dropwise for 2 hours. The temperature in
the flask during dropping was maintained at the reflux temperature
of methyl ethyl ketone. After termination of dropping, the
temperature was maintained at the same temperature for 2 hours.
Then, 5 parts by weight of a methyl ethyl ketone solution
containing 20 wt % of azobis-2-methylbutyronitrile was poured
thereinto, and the resulting solution was stirred for 2 hours.
Thus, the reaction was terminated, and then, the solution was
cooled to obtain acrylic polymer D having a number average
molecular weight of 120,000, an acid value of 92 mg KOH/g and a
glass transition temperature of 61.degree. C.
Production Example 5
[0047] In a four-neck flask equipped with a stirrer, a thermometer,
a condenser, a dropping funnel and a nitrogen gas-introducing pipe,
100 parts by weight of methyl ethyl ketone, 88.6 parts by weight of
methyl methacrylate and 19.4 parts by weight of acrylic acid were
placed, and the temperature thereof was raised to 75.degree. C.
Subsequently, 50 wt % of a previously prepared initiator solution,
i.e., a solution of 1 part by weight of pentaerythritol
tetrakisthioglycolate and 0.3 part by weight of
azobis-2-methylbutyronitrile in 6 parts by weight of methyl ethyl
ketone, was poured thereinto to initiate the reaction. The
temperature in the flask during the reaction was maintained at the
reflux temperature of methyl ethyl ketone. Fifty minutes and 70
minutes after initiation of the reaction, a 25 wt % of the
initiator solution each was added. At the time when it was
confirmed that the conversion ratio of the monomers was 70% or
more, a previously prepared solution of 62.6 parts by weight of
ethyl methacrylate and 9.4 parts by weight of acrylic acid in 66
parts by weight of methyl ethyl ketone was added dropwise for 2
hours. After termination of dropping, the temperature was
maintained at the same temperature for 2 hours. Then, 0.2 part by
weight of azobis-2-methylbutyronitrile was added thereto, and
stirring was continued for 2 hours. Subsequently, the resulting
solution was cooled to obtain acrylic polymer E having a number
average molecular weight of 20,000, an acid value of 125 mg KOH/g,
glass transition temperatures of 30.degree. C. (for the soft
segment) and 95.degree. C. (for the hard segment), and a hard
component/soft component ratio of 6/4.
Comparative Production Example 1
[0048] In a four-neck flask equipped with a stirrer, a thermometer,
a condenser, a dropping funnel and a nitrogen gas-introducing pipe,
100 parts by weight of methyl ethyl ketone was placed, and the
temperature thereof was raised to 75.degree. C. Then, 6.25 parts by
weight of a methyl ethyl ketone containing 20 wt % of
azobis-2-methylbutyronitrile was poured thereinto while blowing
nitrogen gas therein. Subsequently, a previously prepared monomer
mixture consisting of 5.1 parts by weight of acrylic acid, 38.9
parts by weight of methyl methacrylate and 56 parts by weight of
ethyl acrylate was added dropwise for 2 hours. The temperature in
the flask during dropping was maintained at the reflux temperature
of methyl ethyl ketone. After termination of dropping, the
temperature was maintained at the same temperature for 2 hours.
Then, 5 parts by weight of a methyl ethyl ketone containing 20 wt %
of azobis-2-methylbutyronitri- le was poured thereinto, and the
resulting solution was stirred for 2 hours. Thus, the reaction was
terminated, and then, the solution was cooled to obtain acrylic
polymer F having a number average molecular weight of 20,000, an
acid value of 39 mg KOH/g and a glass transition temperature of
18.degree. C.
Comparative Production Example 2
[0049] In a four-neck flask equipped with a stirrer, a thermometer,
a condenser, a dropping funnel and a nitrogen gas-introducing pipe,
100 parts by weight of methyl ethyl ketone was placed, and the
temperature thereof was raised to 75.degree. C. Then, 6.25 parts by
weight of a methyl ethyl ketone solution containing 20 wt % of
azobis-2-methylbutyronitrile was poured thereinto while blowing
nitrogen gas therein. Subsequently, a previously prepared monomer
mixture consisting of 2.6 parts by weight of acrylic acid, 71.3
parts by weight of methyl methacrylate and 26.1 parts by weight of
ethyl acrylate was added dropwise for 2 hours. The temperature in
the flask during dropping was maintained at the reflux temperature
of methyl ethyl ketone. After termination of dropping, the
temperature was maintained at the same temperature for 2 hours.
Then, 5 parts by weight of a methyl ethyl ketone solution
containing 20 wt % of azobis-2-methylbutyronitrile was poured
thereinto, and the resulting solution was stirred for 2 hours.
Thus, the reaction was terminated, and then, the solution was
cooled to obtain acrylic polymer G having a number average
molecular weight of 18,000, an acid value of 19 mg KOH/g and a
glass transition temperature of 63.degree. C.
Comparative Production Example 3
[0050] In a four-neck flask equipped with a stirrer, a thermometer,
a condenser, a dropping funnel and a nitrogen gas-introducing pipe,
100 parts by weight of methyl ethyl ketone was placed, and the
temperature thereof was raised to 75.degree. C. Then, 60 parts by
weight of a methyl ethyl ketone containing 20 wt % of
azobis-2-methylbutyronitrile was poured thereinto while blowing
nitrogen gas therein. Subsequently, a previously prepared monomer
mixture consisting of 11.5 parts by weight of acrylic acid, 62.4
parts by weight of methyl methacrylate and 26.1 parts by weight of
ethyl acrylate was added dropwise for 2 hours. The temperature in
the flask during dropping was maintained at the reflux temperature
of methyl ethyl ketone. After termination of dropping, the
temperature was maintained at the same temperature for 2 hours.
Then, 5 parts by weight of a methyl ethyl ketone solution
containing 20 wt % of azobis-2-methylbutyronitrile was poured
thereinto, and the resulting solution was stirred for 2 hours.
Thus, the reaction was terminated, and then, the solution was
cooled to obtain acrylic polymer H having a number average
molecular weight of 800, an acid value of 90 mg KOH/g and a glass
transition temperature of 17.degree. C.
Synthesis Example 1
[0051] In a four-neck flask equipped with a stirrer, an
air-introducing pipe, a thermometer and a reflux condenser, 120
parts by weight of methyl ethyl ketone, 100 parts by weight of
Pluronic L61 (trade name, manufactured by Asahi Denka Kogyo K.K.)
(ethylene oxide-propylene oxide copolymer) and 20 parts by weight
of Nippollan 980 (trade name, manufactured by Nippon Polyurethane
Co., Ltd.) (polycarbonate diol) were placed, and the temperature
thereof was raised to 60.degree. C., followed by stirring to
dissolve them. Then, the resulting solution was cooled to
40.degree. C., and 14.1 parts by weight of hexamethylene
diisocyanate and 0.05 part by weight of di-n-butyltin dilaurate
were added while blowing air therein. After stirring for 30
minutes, the temperature was raised to 75.degree. C., and the
solution was stirred for 2.5 hours to conduct the reaction.
Subsequently, 7.1 parts by weight of 2-hydroxyethyl acrylate and
0.05 part by weight of methylhydroquinone were added, followed by
stirring for 2 hours to conduct the reaction. Then, the resulting
solution was cooled to 40.degree. C. to obtain polymer A.
Synthesis Example 2
[0052] In a four-neck flask equipped with a stirrer, an
air-introducing pipe, a thermometer and a reflux condenser, 100
parts by weight of methyl ethyl ketone, 60 parts by weight of
Pluronic L61 (trade name, manufactured by Asahi Denka Kogyo K.K.)
(ethylene oxide-propylene oxide copolymer), 15 parts by weight of
Nippollan 980 (trade name, manufactured by Nippon Polyurethane Co.,
Ltd.) (polycarbonate diol) and 25 parts by weight of P-2010 (trade
name, manufactured by Kuraray Co., Ltd.) (polyester polyol) were
placed, and mixed by stirring them at 40.degree. C. for 30 minutes.
Then, 13.4 parts by weight of hexamethylene diisocyanate and 0.05
part by weight of di-n-butyltin dilaurate were added while blowing
air therein. After stirring for 30 minutes, the temperature was
raised to 75.degree. C., and the solution was stirred for 2.5 hours
to conduct the reaction. Subsequently, 3.6 parts by weight of
hexamethylene diisocyanate, 7.1 parts by weight of 2-hydroxyethyl
acrylate and 0.05 part by weight of methylhydroquinone were added,
followed by stirring for 2 hours to conduct the reaction. Then, the
resulting solution was cooled to 40.degree. C. to obtain polymer
B.
Synthesis Example 3
[0053] Polymer C was obtained in the same manner as in Synthesis
Example 1 except that 21 parts by weight of methylene-bis-(4-phenyl
isocyanate) was used in place of 14.1 parts by weight of
hexamethylene diisocyanate.
Comparative Synthesis Example 1
[0054] Polymer D was obtained in the same manner as in Synthesis
Example 1 except that the reaction was conducted by stirring for
2.5 hours using 10.1 parts by weight of hexamethylene diisocyanate,
followed by cooling to 40.degree. C. without addition of
2-hydroxyethyl acrylate.
Comparative Synthesis Example 2
[0055] In a four-neck flask equipped with a stirrer, an
air-introducing pipe, a thermometer and a reflux condenser, 50
parts by weight of methyl ethyl ketone, 14.2 parts by weight of
hexamethylene diisocyanate, 15.6 parts by-weight of 2-hydroxyethyl
acrylate, 0.02 part by weight of di-n-butyltin dilaurate and 0.03
part by weight of methylhydroquinone were placed. After stirring
for 30 minutes, the temperature was raised to 75.degree. C., and
the resulting solution was stirred for 2.5 hours to conduct the
reaction. Then, the solution was cooled to 40.degree. C. to obtain
polymer E.
Example 1
[0056] In a four-neck flask equipped with a stirrer, an
air-introducing pipe, a thermometer and a reflux condenser, 85.7
parts by weight of polymer A obtained in Synthesis Example 1 and
200 parts by weight of acrylic polymer A obtained in Production
Example 1 were placed, and mixed by stirring them at 40.degree. C.
for 30 minutes while blowing air therein. Then, the temperature was
raised to 75.degree. C., and the resulting solution was stirred for
3 hours to conduct the reaction. After the reaction, 20 parts by
weight of IRR213 (trade name, manufactured by Daicel UCB Co.,
Ltd.)(urethane acrylate), 2 parts by weight of
2-dimethoxy-1,2-diphenylethane-1-one and 0.05 part by weight of
methylhydroquinone were added thereto, and mixed by stirring them
to obtain a photosensitive resin solution. This solution was
extruded to a thickness of 1.6 mm by means of a twin extruder,
removing the solvent under reduced pressure, and the extruded sheet
was laminated with a PET film provided with an adhesive layer and a
PET film coated with polyvinyl alcohol, thereby obtaining a
photosensitive resin plate.
[0057] The above-mentioned photosensitive resin plate was
irradiated with an actinic ray to harden the photosensitive resin
up to a depth of 0.6 mm from the side of the PET film provided with
the adhesive layer by use of an FL-40BL chemical lamp (manufactured
by Toshiba Corp.). Subsequently, the PET film on the opposite side
was separated, and a negative film was adhered to the
photosensitive resin under vacuum. Then, the photosensitive resin
plate was irradiated for 10 minutes to perform exposure. After the
exposure, the photosensitive resin plate was developed at
30.degree. C. using a 2.38 wt % aqueous solution of
tetramethylammonium hydroxide, dried at 60.degree. C. for 15
minutes, and further postexposed for 5 minutes by use of a chemical
lamp, thereby obtaining a flexographic resin plate. The prepress
processing characteristics and the physical properties after
hardening were examined. Using the resulting plate as the
flexographic resin plate, printing was done on hard paper (aqueous
ink used: DF-040 (red), DF-260 (black) and DF-140 (ultramarine)
available from SAKATA CORPORATION), and the ink resistance and the
press life were examined.
[0058] Results of the evaluation are shown in Table 1.
Example 2
[0059] A flexographic resin plate was prepared using a
photosensitive resin plate obtained in the same manner as in
Example 1 except that 171.4 parts by weight of polymer A obtained
in Synthesis Example land 211.4 parts by weight of acrylic polymer
B obtained in Production Example 2 were used. Results of the
evaluation therefor are shown in Table 1.
Example 3
[0060] A flexographic resin plate was prepared using a
photosensitive resin plate obtained in the same manner as in
Example 1 except that 257.1 parts by weight of polymer A obtained
in Synthesis Example land 206.2 parts by weight of acrylic polymer
C obtained in Production Example 3 were used. Results of the
evaluation therefor are shown in Table 1.
Example 4
[0061] A flexographic resin plate was prepared using a
photosensitive resin plate obtained in the same manner as in
Example 1 except that 210.7 parts by weight of polymer B obtained
in Synthesis Example 2 and 206.2 parts by weight of acrylic polymer
C obtained in Production Example 3 were used. Results of the
evaluation therefor are shown in Table 1.
Example 5
[0062] A flexographic resin plate was prepared using a
photosensitive resin plate obtained in the same manner as in
Example 1 except that 264 parts by weight of polymer C obtained in
Synthesis Example 3 and 206.2 parts by weight of acrylic polymer C
obtained in Production Example 3 were used. Results of the
evaluation therefor are shown in Table 1.
Example 6
[0063] A flexographic resin plate was prepared using a
photosensitive resin plate obtained in the same manner as in
Example 1 except that 171.4 parts by weight of polymer A obtained
in Synthesis Example 1 and 206.2 parts by weight of acrylic polymer
D obtained in Production Example 4 were used. Results of the
evaluation therefor are shown in Table 1.
Example 7
[0064] A flexographic resin plate was prepared using a
photosensitive resin plate obtained in the same manner as in
Example 1 except that 257.1 parts by weight of polymer A obtained
in Synthesis Example 1 and 193.4 parts by weight of acrylic polymer
E obtained in Production Example 5 were used. Results of the
evaluation therefor are shown in Table 1.
Comparative Example 1
[0065] A flexographic resin plate was prepared using a
photosensitive resin plate obtained in the same manner as in
Example 1 except that 211.4 parts by weight of acrylic polymer F
obtained in Comparative Production Example 1 was used in place of
acrylic polymer A. Results of the evaluation therefor are shown in
Table 1.
Comparative Example 2
[0066] A flexographic resin plate was prepared using a
photosensitive resin plate obtained in the same manner as in
Example 1 except that 211.4 parts by weight of acrylic polymer G
obtained in Comparative Production Example 2 was used in place of
acrylic polymer A. Results of the evaluation therefor are shown in
Table 1.
Comparative Example 3
[0067] A flexographic resin plate was prepared using a
photosensitive resin plate obtained in the same manner as in
Example 1 except that 259.7 parts by weight of acrylic polymer H
obtained in Comparative Production Example 3 was used in place of
acrylic polymer A. Results of the evaluation therefor are shown in
Table 1.
Comparative Example 4
[0068] A flexographic resin plate was prepared using a
photosensitive resin plate obtained in the same manner as in
Example 1 except that 250.1 parts by weight of polymer D obtained
in Comparative Synthesis Example 1 and 206.2 parts by weight of
acrylic polymer C obtained in Production Example 3 were used.
Results of the evaluation therefor are shown in Table 1.
Comparative Example 5
[0069] A flexographic resin plate was prepared using a
photosensitive resin plate obtained in the same manner as in
Example 1 except that 79.9 parts by weight of polymer E obtained in
Comparative Synthesis Example 2 and 206.2 parts by weight of
acrylic polymer C obtained in Production Example 3 were used, and
the amount of IRR213 (trade name, manufactured by Daicel UCB Co.,
Ltd.) (urethane acrylate) added after the reaction was changed to
50 parts by weight. Results of the evaluation therefor are shown in
Table 1.
Comparative Example 6
[0070] To the photosensitive resin solution obtained in Comparative
Example 4, 7.1 parts by weight of 2-hydroxyethyl acrylate was
further added. Using the resulting solution, a flexographic resin
plate was prepared in the same manner as in Example 1. Results of
the evaluation are shown in Table 1. In the flexographic resin
plate prepared, 2-hydroxyethyl acrylate was not reacted, so that
the performance thereof was insufficient.
1 TABLE 1 Develop- ing Impact Ink Total Time Sensi- Resilience
Resist- Press Evalu- (min) tivity (%) ance Life ation Example 1 20
9 32 B C B Example 2 18 11 36 B B B Example 3 13 13 41 B B A
Example 4 15 14 45 A A A Example 5 13 13 30 B B B Example 6 25 12
34 B A B Example 7 13 13 47 A B A Comparative 20 9 18 B C D Example
1 Comparative 30 8 29 A C D Example 2 Comparative 25 8 13 C D D
Example 3 Comparative 13 6.5 33 D C C Example 4 Comparative 10 7 10
or B B D Example 5 less Comparative 13 7 31 D C C Example 6
[0071] In the table, the sensitivity is shown by the hardening step
number of a 21-step tablet manufactured by Kodak Co. The impact
resilience is measured by means of a JIS impact resilience testing
machine (manufactured by Kabushiki Kaisya Kawashima Seisakusyo)
according to JIS K 6301-11. The ink resistance is represented by
the number of prints at which poor printing occurs by expansion,
wherein "A" indicates 500,000 or more prints, "B" indicates 100,000
to less than 500,000 prints, "C" indicates 50,000 to less than
100,000 prints, and "D" indicates less than 50,000 prints. The
press life is represented by the number of prints at which poor
printing occurs by wear and shaving, wherein "A" indicates 500,000
or more prints, "B" indicates 200,000 to E less than 500,000prints,
"C" indicates 50,000 to less than 200,000 prints, and "D" indicates
less than 50,000 prints. In the total evaluation, "A" is evaluated
as particularly highly practical, "B" as practical, "C" as usable,
but practically having a problem, and "D" as unusable.
[0072] As apparent from Table 1 shown above, the photosensitive
resin compositions of the present invention are high in sensitivity
and impact resilience, and excellent in ink resistance and press
life. In particular, the use of hexamethylene diisocyanate as the
compound having two isocyanate groups in one molecule results in
high impact resilience, as shown in Examples 1 to 4, 6 and 7.
Further, the use of the polyether diol as the compound having two
hydroxyl groups in one molecule increases flexibility and impact
resilience. Furthermore, it can be inferred that the use of
2-hydroxyethyl acrylate as the photopolymerizable unsaturated
monomer improves the sensitivity.
[0073] Industrial Application Field
[0074] The photosensitive resin compositions of the present
invention can be easily developed with water or a diluted alkaline
aqueous solution, and moreover, are high in sensitivity and impact
resilience. The printing plate materials prepared therefrom are
excellent in ink resistance and press life, and excellent as a
printing material for thick printing plate materials such as
corrugated fiberboards.
* * * * *