U.S. patent application number 09/775988 was filed with the patent office on 2002-05-30 for near ir sensitive photoimageable/photopolymerizable compositions, media, and associated processes.
Invention is credited to Fabricius, Dietrich M., Weed, Gregory C..
Application Number | 20020064728 09/775988 |
Document ID | / |
Family ID | 27108088 |
Filed Date | 2002-05-30 |
United States Patent
Application |
20020064728 |
Kind Code |
A1 |
Weed, Gregory C. ; et
al. |
May 30, 2002 |
Near IR sensitive photoimageable/photopolymerizable compositions,
media, and associated processes
Abstract
Novel photopolymer compositions are disclosed which contain dyes
that absorb strongly in the near infrared (near IR) region of the
electromagnetic spectrum. These dyes are useful as photosensitizers
for initiating a variety of photoimaging and photopolymerization
reactions. Imaging Media are disclosed herein which are sensitive
in the near infrared (near IR) region of the electromagnetic
spectrum and which can initiate polymerization of ethylenically
unsaturated monomer components in negative-acting photopolymer
systems and/or which can initiate conversion of a leuco dye to its
corresponding colored dye form. These imaging media comprise either
a near IR dye photochemical sensitizer, a hexaarylbiimidazole
(HABI) photoinitiator, a chain transfer agent, and a
photopolymerizable material or a near IR dye photochemical
sensitizer, a hexaarylbiimidazole (HABI) photoinitiator, and a
leuco dye. These imaging media are useful in a variety of
photopolymer products, including photoresists, proofing films, and
holographic recording films.
Inventors: |
Weed, Gregory C.; (Towanda,
PA) ; Fabricius, Dietrich M.; (Hendersonville,
NC) |
Correspondence
Address: |
E I DU PONT DE NEMOURS AND COMPANY
LEGAL DEPARTMENT - PATENTS
1007 MARKET STREET
WILMINGTON
DE
19898
US
|
Family ID: |
27108088 |
Appl. No.: |
09/775988 |
Filed: |
February 2, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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09775988 |
Feb 2, 2001 |
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08888242 |
Jul 3, 1997 |
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08888242 |
Jul 3, 1997 |
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08708476 |
Sep 5, 1996 |
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Current U.S.
Class: |
430/281.1 |
Current CPC
Class: |
H05K 3/3452 20130101;
Y10S 430/116 20130101; Y10S 430/121 20130101; B41C 1/1008 20130101;
G03F 7/031 20130101; H05K 3/0082 20130101; B41C 2210/06 20130101;
G03C 1/732 20130101; B41C 2210/12 20130101; B41C 2210/24 20130101;
B41C 2210/22 20130101; B41C 2210/02 20130101; B41M 5/368 20130101;
G03C 5/164 20130101; B41C 2210/04 20130101; G03C 2200/37 20130101;
G03F 3/10 20130101; B41M 5/30 20130101; G03C 1/732 20130101; G03C
5/164 20130101; G03C 2200/37 20130101 |
Class at
Publication: |
430/281.1 |
International
Class: |
G03C 001/725 |
Claims
What is claimed is:
1. A near infrared sensitive composition, comprising: (a) a near
infrared dye photochemical sensitizer which is substantially free
of borate anion that enables the composition to undergo either (i)
effective photopolymerization or (ii) effective photoimaging upon
exposure to near infrared radiation, the near infrared dye is a
compound of formula I: 57wherein substituent A is chosen from (1) a
5-6 membered heterocyclic ring system having 1-3 ring heteroatoms,
in which the heteroatom is a nitrogen atom, which is substituted
with a hydrogen atom, C.sub.1-C.sub.6 alky
(CH.sub.2).sub.m-CO.sub.2H or
(CH.sub.2).sub.m-CO.sub.2(C.sub.1-C.su- b.6 alkyl) and the carbon
atom of the herocyclic ring system may be substituted with an
oxygen atom to form a carbonyl or enolate anion and m is an integer
ranging from 0-4; (2) a 5-6 membered carbocyclic moiety substituted
with a hydrogen atom or a C.sub.1-C.sub.6 alkyl group wherein a
carbon atom of the alkyl group may be substituted with oxygen to
form a carbonyl or enolate anion; (3) a quinoline or isoquinoline
group wherein the nitrogen atom is directly bonded to the
carbocyclic moiety of formula I; (4) N,N-bisaryl or
bis(C.sub.1-C.sub.6 alkyl) or bisaryl(C.sub.1-C.sub.6 alkyl) amine
wherein the aryl group is a naphthyl or phenyl group which is
unsubstituted or substituted with a fluorine atom, bromine atom,
chlorine atom, OCH.sub.3, CF.sub.3, OH, or C.sub.1-C.sub.6 alkyl;
(5) a heterocyclic ring system having at least one nitrogen atom
bonded directly to the carbocyclic ring of formula I and a group Z
which is a carbon atom, NR.sup.8, oxygen atom or sulfur atom
wherein R.sup.8 is a hydrogen atom, C.sub.1-C.sub.6 alkyl,
CO.sub.2H or CO.sub.2-C.sub.1-C.sub.6 alkyl; substitutent D.sub.1
is a 9-15 membered heterocyclic system comprising a heteroaryl ring
system having at least one heteroatom group (U) which is an
NR.sup.3 group, oxygen atom, sulfur atom or PR.sup.3 group which is
directly bonded to the aryl portion of the heteroaryl ring system
and wherein R.sup.3 is a C.sub.1-C.sub.6 alkyl which may be
unsubstituted or substituted with CO.sub.2H, SO.sub.3H or salts
thereof and wherein the aryl ring may be unsubstituted or
substituted with OCH.sub.3, CF.sub.3, bromine atom, chlorine atom,
fluorine atom, C.sub.1-C.sub.6 alkyl or OH or a fused ring
polycyclic hetercyclic system; substituent D.sub.2 has the
identical heterocyclic system as substituent D.sub.1 except that
when U is NR.sup.3, the nitrogen atom is quaternized to form an
amine salt which is neutralized by an enolate anion from A when A
is a substituted pyrimidine like moiety or by a discrete (non
intra-molecular) anion; n is an integer ranging from 1-2; (b) a
hexaarylbiimidazole compound as photoinitiator; (c) a
photopolymerizable material and a chain transfer agent, or, instead
of (c), (d) a photoimageable dye.
2. A photopolymerizable element comprising: (a) a support, (b) a
photopolymerizable composition comprising (i) a near infrared dye
photochemical sensitizer which is substantially free of borate
anion that enables the photopolymerizable composition to undergo
effective photopolymerization upon exposure to near infrared
radiation, the near infrared dye is a compound of formula I:
58wherein A is: (1) a 5-6 membered heterocyclic ring system having
1-3 ring heteroatoms, in which the heteroatom is a nitrogen atom
which is substituted with a hydrogen atom, C.sub.1-C.sub.6 alkyl,
(CH.sub.2).sub.m-CO.sub.2H or
(CH.sub.2).sub.m-CO.sub.2(C.sub.1-C.sub.6 alkyl) and the carbon
atom of the heterocyclic ring system may be substituted with an
oxygen atom to form a carbonyl or enolate anion and m is 0-4; (2) a
5-6 membered carbocyclic moiety substituted with hydrogen atom,
C.sub.1-C.sub.6 alkyl group wherein the carbon atom of the alkyl
group may be substituted with oxygen to form a carbonyl or enolate
anion; (3) quinoline or isoquinoline groups wherein the nitrogen
atom is directly bonded to the carbocyclic moiety of formula I; (4)
N,N-bisaryl or bis(C.sub.1-C.sub.6 alkyl) or
bisaryl(C.sub.1-C.sub.6 alkyl) amine wherein the aryl group is a
napthyl or phenyl group which is unsubstituted or substituted with
fluorine atom, bromine atom, chlorine atom, OCH.sub.3, CF.sub.3,
OH, C.sub.1-C.sub.6 alkyl; (5) a heterocyclic ring system having at
least one nitrogen atom bonded directly to the carbocyclic ring of
formula I and a group Z which is a carbon atom, NR.sup.8, oxygen
atom, or sulfur atom wherein R.sup.8 is a hydrogen atom,
C.sub.1-C.sub.6 alkyl, CO.sub.2H or CO.sub.2-C.sub.1-C.sub.6 alkyl;
substituent D.sub.1 is a 9-15 membered heterocyclic system
comprising a heteroaryl ring having at least one heteroatom group
(U) which is an NR.sup.3 group, oxygen atom, sulfur atom, or
PR.sup.3 group which is directly bonded to the aryl portion of the
heteroaryl ring system and wherein R.sup.3 is a C.sub.1-C.sub.6
alkyl which may be unsubstituted or substituted with CO.sub.2H,
SO.sub.3H or salts thereof and wherein the aryl ring may be
unsubstituted or substituted with OCH.sub.3, CF.sub.3, bromine
atom, chlorine atom, fluorine atom, C.sub.1-C.sub.6 alkyl or OH or
a fused ring polycyclic heterocyclic system; substituent D.sub.2
has the identical heterocyclic system as substituent D.sub.1 except
that when U is NR.sub.3, the nitrogen atom is quatemized to form an
amine salt which is neutralized by an enolate anion from A when A
is a substituted pyrimidine like moiety or by a discrete (non
intra-molecular) anion; n is an integer ranging from 1-2; (c) a
hexaarylbiimidazole compound as photoinitiator; (d) a
photopolymerizable material and a chain transfer agent; and (e) a
binder polymer.
3. A near infrared sensitive composition, comprising: (a) a near
infrared dye photochemical sensitizer which is substantially free
of borate anion that enables the composition to undergo either (i)
effective photopolymerization or (ii) effective photoimaging upon
exposure to near infrared radiation, the near infrared dye is a
compound of formula I: 59wherein substituent A is 60D1 is: 61D2 is
62R.sup.1 or R.sup.2 are independently selected from H,
C.sub.1-C.sub.6 alkyl; or aryl wherein aryl is phenyl or napthyl
which may be unsubstituted or substituted with halogen,
--O(C.sub.1-C.sub.6 alkyl), --Oaryl, aryl or CF.sub.3;
(C.sub.1-C.sub.6 alkyl) (C.sub.1-C.sub.10 aryl) or hydrogen; is an
aromatic ring chosen from phenyl or napthyl; 63is a heteroaryl ring
chosen from benzopyrazine, benzo-1,4-oxazine or benzo-1,4-thiazine.
U is selected from NR.sup.3, S, PR.sup.3 or O; Y is selected from
C(R.sup.1)(R.sup.2); or U, wherein R.sup.1 and R.sup.2 are as
defined above; 64R.sup.3 is selected from C.sub.1-C.sub.6 alkyl
unsubstituted or substituted with CO.sub.2H, SO.sub.3H or salts
thereof; R.sup.4-R.sup.7 are independently chosen from H,
OCH.sub.3, CF.sub.3, halogen; Z is chosen from NR.sup.8, C, O or S;
R.sup.8 is chosen from H, C.sub.1-C.sub.6 alkyl,
(CH.sub.2).sub.mCO.sub.2H or
(CH.sub.2).sub.mCO.sub.2(C.sub.1-C.sub.6 alkyl); and m is 0-6; n is
1-2; provided that when A contains an enolate anion, a counterion
L.sup.O is not present; (b) a hexaarylbiimidazole compound as
photoinitiator; (c) a photopolymerizable material and a chain
transfer agent; or, instead of (c), (d) a photoimageable dye.
4. A photopolymerizable element comprising: (a) a support; (b) a
photopolymerizable composition comprising (i) a near infrared dye
photochemical sensitizer which is substantially free of borate
anion that enables the photopolymerizerable composition to undergo
effective photopolymerization upon exposure to neared infrared
radiation, the near infrared dye is a compound of formula I:
65wherein A is 66D.sub.1 represents a heterocyclic ring structure
selected from the group consisting of: 67D.sub.2 represents a
heterocyclic ring structure selected from the group consisting of
68R.sup.1 or R.sup.2 are independently selected from:
C.sub.1-C.sub.6 alkyl, aryl wherein aryl is phenyl or napthyl which
may be unsubstituted or substituted with halogen,
--O(C.sub.1-C.sub.6 alkyl), Oaryl, aryl or CF.sub.3,
(C.sub.1-C.sub.6 alkyl) aryl or hydrogen; R3 is C.sub.1-C.sub.6
alkyl, C.sub.1-C.sub.6 alkylsulfonate, C.sub.1-C.sub.6
alkyloxycarbonyl, C.sub.1-C.sub.6 alkyl, or C.sub.1-C.sub.6
alkylcarboxy; Z is selected from NR.sup.8, C, O or S wherein
R.sup.8 is H, C.sub.1-C.sub.6 alkyl, CO.sub.2H or
CO.sub.2(C.sub.1-C.sub.6 alkyl); R.sup.4-R.sup.7 are independently
selected from H, OCH.sub.3, CF.sub.3; or any two of R.sup.4-R.sup.7
which when ortho substituents may join to form a phenyl ring; n is
an integer ranging from 1-2 with the proviso that D.sub.2 is
selected to be the quatemized heterocylic ring structure that
corresponds to D.sub.1 such that D.sub.1 and D.sub.2 together form
a pair of heterocyclic ring structures; (c) a hexaarylbiimidazole
compound as photoinitiator; (d) a photopolymerizable material and a
chain transfer agent; and (e) a binder polymer.
5. A near infrared sensitive composition, comprising: (a) a near
infrared dye photochemical sensitizer which is substantially free
of borate anion that enables the composition to undergo either (i)
effective photopolymerization or (ii) effective photoimaging upon
exposure to near infrared radiation wherein the near infrared dye
is selected from the group consisting of DF-1413, DF-1419, DF-1422,
DF-1429, DF-1668, DF-12124, DF-15118, DF-15131, DF-15132, NK-3877,
GW-826, GW-436, GW-776, GW-976, GW-186, and NK-2268; (b) a
hexaarylbiimidazole compound selected from the group consisting of
o-Cl-HABI, CDM-HABI, 2,3,5-TCl-HABI, and TCTM-HABI; and (c) a
photopolymerizable material selected from the group consisting of
tripropylene glycol diacrylate, trimethylolpropane triacrylate,
ethoxylated trimethylolpropane triacrylate, propoxylated
trimethylolpropane triacrylate, ethoxylated Bisphenol A
dimethacrylate, and triethylene glycol dimethacrylate, and a chain
transfer agent selected from the group consisting of
N-phenylglycine, julolidine, 2-mercaptobenzoxazole,
2,6-diisopropyl-N,N-dimethylaniline, a borate salt and an organic
thiol.
6. The composition according to claim 3 wherein A is selected from
the group consisting of 69D.sub.1 represents a heterocyclic ring
structure selected from the group consisting of 70D.sub.2
represents a heterocyclic ring structure selected from the group
consisting of 71R.sub.1 or R.sub.2 are independently selected from:
C.sub.1-C.sub.6 alkyl; aryl wherein aryl is phenyl or napthyl which
may be unsubstituted or substituted with halogen,
--O(C.sub.1-C.sub.6 alkyl), Oaryl, aryl or phenyl, CF.sub.3
(C.sub.1-C.sub.6 alkyl)(C.sub.1-C.sub.10 aryl) or hydrogen; R.sub.3
is C.sub.1-C.sub.6 alkyl, C.sub.1-C.sub.6 alkylsulfonate,
C.sub.1-C.sub.6 alkyloxycarbonyl, C.sub.1-C.sub.6 alkyl, or carboxy
C.sub.1-C.sub.6 alkyl; Z is selected from NR.sup.8, C, O or S
wherein R.sup.8 is H, C.sub.1-C.sub.6 alkyl, CO.sub.2H or
CO.sub.2(C.sub.1-C.sub.6 alkyl); R.sup.4-R.sup.7 are independently
selected from H, OCH.sub.3, CF.sub.3; or any two of R.sup.4-R.sup.7
which when ortho substituents may join to form a phenyl ring; with
the proviso that D.sub.2 is selected to be the quatemized
heterocylic ring structure that corresponds to D.sub.1 such that
D.sub.1 and D.sub.2 together form a pair of heterocyclic ring
structures.
7. The composition according to claim 3, wherein the near infrared
dye is selected from the group consisting of DF-1413, DF-1419,
DF-1422, DF-1429, DF-1668, DF-12124, DF-15118, DF-15131,
DF-15132,NK-3877, GW-826, GW-436, GW-776, GW-976, GW-186, and
NK-2268; the hexaarylbiimidazole compound is selected from the
group consisting of o-Cl-HABI, CDM-HABI, 2,3,5-TCl-HABI, and
TCTM-HABI; wherein the photopolymerizable material is selected from
the group consisting of tripropylene glycol diacrylate,
trimethylolpropane triacrylate, ethoxylated trimethylolpropane
triacrylate, propoxylated trimethylolpropane triacrylate,
ethoxylated Bisphenol A dimethacrylate, and triethylene glycol
dimethacrylate, and the chain transfer agent is selected from the
group consisting of N-phenylglycine, julolidine,
2-mercaptobenzoxazole, 2,6-diisopropyl-N,N-dimethylaniline, and an
organic thiol; or the photoimageable dye is selected from the group
consisting of LCV, LECV, LPCV, LBCV, LV-1, LV-2 and LV-3.
8. The composition according to claims 1, 2, 3 or 4 wherein the
near infrared dye is present in at least 0.5% by weight of the
total composition; the hexaarylbiimidazole compound is present in
at least 0.5% by weight of the total composition; and the
photopolymerizable material is present in at least 20% by weight of
the total composition and the chain transfer agent is present in at
least 0.1 % by weight of the total composition; or the
photoimageable dye is present in at least 0.5% by weight of the
total composition.
9. The composition according to claims 1, 2, 3, 4 or 5 which
further comprises a binder polymer.
10. The composition according to claims 1, 2, 3 or 4 wherein the
composition, containing at least 0.5 weight percent of the near
infrared dye, undergoes either (1) effective photopolymerization or
(2) effective photoimaging to a photopolymerized or photoimaged
photopolymer upon exposure to near infrared actinic radiation at a
fluence of at least 100 mW/cm.sup.2 (fluence units) for a period of
at least 2 seconds (time units).
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This is a continuation-in-part application of U.S. patent
application Ser. No. 08/708,476, filed Sep. 5, 1996 (abandoned),
and of copending U.S. patent application Ser. No. 08/888242,filed
Jul. 3, 1997, which is incorporated herein by reference in its
entirety.
FIELD OF THE INVENTION
[0002] The invention is in the area of photopolymer compositions
and photoimaging media (elements) and associated processes that can
be photoimaged and/or photopolymerized by actinic radiation in the
near-IR range (.about.770-1500 nm) of the electromagnetic
spectrum.
BACKGROUND OF THE INVENTION
[0003] Various dyes are known to the art that are infrared (IR)
absorbers and which can act as photothermal sensitizers for various
reactions that are initiated using near IR radiation. Examples
include the SQS and related squarylium dyes disclosed in U.S. Pat.
No. 5,019,549 which are useful dyes for use in donor elements for
laser-induced thermal imaging processes.
[0004] The hexaarylbiimidazoles (HABIs) are a very useful class of
photoinitiators that are widely known to those skilled in the art
and which are used in many photopolymer products. Some key HABI
review articles include the following: "Photoinitiators for
Free-Radical-Initiated Photoimaging Systems", B. Monroe and G.
Weed, Chem. Rev., 93, p. 435-448 (1993), see p. 440-441 for the
section on HABIs; and "Photopolymers: Radiation Curable Imaging
Systems" by B. M. Monroe, Chapter 10 in Radiation Curing: Science
and Technology, edited by S. P. Pappas, Plenum Press, New York,
(1992), see p. 407-412 for the section on HABIs.
[0005] There are various compounds known that are sensitizers of
HABIs for photopolymer processes effected with actinic radiation in
the ultraviolet and visible regions of the electromagnetic
spectrum. It would be very desirable to have efficient sensitizers
of HABIs for photopolymer processes in the near infrared
(.about.770-1500 nm) of the electromagnetic spectrum, particularly
since this type of actinic radiation is readily available from
inexpensive diode lasers that can be employed for direct digital
imaging. Efficient sensitizers of HABIs active in the near infrared
are not currently known to the art, and there is a strong need to
have efficient sensitizers of HABIs with sensitization in the near
infrared region of the electromagnetic spectrum.
[0006] In Japanese patent publication 08-297364, there are
disclosed some near infrared cationic dyes present in
photosensitive image-forming sheets that sensitize HABIs. All of
these dyes though have a borate anion, which is a well-known
coinitiator of HABI(s), present as counterion. Since borate anion
is present in these compositions, the dyes would sensitize HABIs.
Having a borate anion present as counterion can be disadvantageous,
since this anion is relatively large tending to impart limited
solubility to the dye and hence likely making it difficult to
tailor properties of compositions comprising these dyes. These
compositions are comprised of three essential components--near IR
dye, borate anion, and HABI. A two component composition--near IR
dye and HABI-of the present invention obviates the need for the
large borate anion.
SUMMARY OF THE INVENTION
[0007] Novel photopolymer compositions and photoimaging media
(elements) are disclosed which contain dyes that absorb strongly in
the near infrared (near IR) region of the electromagnetic spectrum.
These dyes are useful as efficient photosensitizers in sensitizing
photoinitiators that can initiate photopolymerization and other
photoimaging reactions. These photopolymer compositions and
photoimaging media are sensitive in the near infrared (near IR)
region of the electromagnetic spectrum and are characterized in
undergoing polymerization of ethylenically unsaturated monomer
components or other photopolymerizable materials, preferably in
negative-acting photopolymer systems, and/or other photoimaging
reactions that are initiated by exposure to near IR actinic
radiation. These compositions and photoimaging media, in a first
embodiment, comprise a near IR dye photochemical sensitizer, which
is substantially free of borate anion, a hexaarylbiimidazole (HABI)
compound as photoinitiator, a chain transfer agent, and a
photopolymerizable material, which preferably is an ethylenically
unsaturated monomer. These compositions and photoimaging media, in
a second embodiment, comprise a near IR dye photochemical
sensitizer, which is substantially free of borate anion, a
hexaarylbiimidazole (HABI) compound as photoinitiator, and a leuco
dye. Additional embodiments involve processes using the
compositions of this invention and elements containing the
compositions of this invention. These compositions and photoimaging
media are useful in a variety of photopolymer products, including
photoresists, solder masks, proofing films, flexographic printing
products, and holographic recording films.
DETAILED DESCRIPTION OF THE INVENTION
[0008] A key aspect of the present invention is the discovery that
certain dyes that absorb in the near infrared and which are
substantially free of a borate anion are efficient sensitizers of
hexaarylbiimidazoles (HABIs), which as a class of photoinitiators
are well known to those skilled in the art to be difficult to
sensitize especially in the longer wavelength regions. Furthermore,
in sharp contrast to many known photosensitizers, the
photosensitizers of this invention are effective in bringing about
polymerization upon exposure in a photopolymerizable film over a
considerably larger film thickness in comparison to what the known
sensitizers can do. While not being bound by any theory, the
photosensitizers of this invention are believed to act via a
photochemical mechanism that involves, after excitation of the
photosensitizer to an excited state upon exposure to actinic
radiation, electron transfer from the excited photosensitizer to
the HABI and then subsequent cleavage of the HABI to give a
triarylimidazole radical (lophyl radical). The lophyl radical may
either serve as the initiator directly or may indirectly afford via
reaction with a hydrogen donor other radical(s) that serve to
initiate photopolymerization and/or photoimaging. If the oxidation
potential of the near IR photosensitizer is too high in relation to
the reduction potential of the HABI, then electron transfer will be
inefficient or may not occur at all, and the near IR
photosensitizer will not be a photochemical sensitizer of the HABI.
If, on the other hand, the oxidation potential of the near IR
photosensitizer is suitably low in relation to the reduction
potential of the HABI, then according to the well-known Marcus
theory for electron transfer, the donation of an electron from the
dye to the HABI should be efficient and the dye may be an efficient
photochemical sensitizer of the HABI initiator.
[0009] The present invention, therefore, relates to a method for
generating HABI radicals which act as photoinitiators in
photochemical compositions comprising exposing a composition
comprising a near IR dye; a HABI photoinitiator; and a
photoactivatable compound to near infrared radiation wherein the
near IR dye is activated to an excited state IR dye* which
subsequently transfers an electron to the HABI photoinitiator which
leads to the formation of HABI radicals. In a specific embodiment
the near infrared absorbing dye is free of borate anion in which
regard the invention may be considered to consist essentially of
the near infrared absorbing dye and the HABI together with the
other ingredients.
[0010] In a first embodiment which entails photopolymerization of a
photopolymerizable (photohardenable) material to afford
photopolymerized (photohardened) photopolymer, the compositions are
comprised of the following components:
[0011] 1) a photoinitiator system; which comprises:
[0012] A) a near IR dye photochemical sensitizer; and
[0013] B) a hexaarylbiimidazole (HABI) compound as
photoinitiator;
[0014] 2) a chain transfer agent; and
[0015] 3) a photopolymerizable material, which preferably is an
ethylenically unsaturated monomer,
[0016] with the proviso that the near IR dye photochemical
sensitizer is substantially free of borate anion.
[0017] In a second embodiment which entails photoimaging of a
photoimageable material to afford an image comprising photoimaged
photopolymer, the photoimageable compositions are comprised of the
following components:
[0018] 1) a photoinitiator system; which comprises:
[0019] A) a near IR dye photochemical sensitizer; and
[0020] B) a hexaarylbiimidazole (HABI) compound as photoinitiator;
and
[0021] 2) a leuco dye,
[0022] with the proviso that the near IR dye photochemical
sensitizer is substantially free of borate anion.
[0023] Both the compositions of the first embodiment and the
compositions of the second embodiment may contain additional
components, such as other components that are typically present in
photopolymer compositions. The additional components include but
are not limited to polymeric binder(s), additional components of
the types named above (e.g., additional HABI initiator(s),
additional leuco dye(s), additional monomer(s), etc.), as well as
other optional components such as fillers, pigments, surfactants,
adhesion modifiers, scum formation modifiers, and the like.
Furthermore, the compositions of the first embodiment may contain
but are not required to contain leuco dye(s), and the compositions
of the second embodiment may contain but are not required to
contain photopolymerizable (photohardenable) material(s).
[0024] Unless specifically indicated otherwise, the discussion
presented below on the component specifications and details applies
equally to both the first and second embodiments of this
invention.
HABI Photoinitiator/Near IR Photosensitizer Photoinitiator
System
[0025] The photoinitiator or photoinitiating system includes one or
more hexaarylbiimidazole (HABI) compounds which directly furnish
free-radicals when activated by actinic radiation. By "actinic
radiation" is meant radiation which allows formation of the
free-radicals necessary to initiate polymerization of the monomer.
This photoinitiating system can also include a plurality of
compounds, one or more of which yields the free-radicals after
having been caused to do so by another compound, a photosensitizer
or sensitizer, which is activated by the radiation. The
photosensitizer in this invention extends spectral response into
the near infrared (near-IR) spectral region. Also radiation
employing a laser can be employed in specific situations.
[0026] Substituted 2,4,5,2',4',5'-hexaarylbiimidazole dimers
(HABIs) useful in the invention are disclosed in: Chambers, U.S.
Pat. No. 3,479,185;-Cescon, U.S. Pat. No. 3,784,557; Dessauer, U.S.
Pat. No. 4,311,783; and Sheets, U.S. Pat. No. 4,622,286. Preferred
dimers of this class are 2-o-chlorosubstituted
hexaphenylbiimidazoles in which the other positions on the phenyl
radicals are unsubstituted or substituted with chloro, methyl or
methoxy, such as: CDM-HABI, i.e.,
2-(o-chlorophenyl)-4,5-bis(m-methoxyphenyl)-imidazole dimer;
o-Cl-HABI, i.e., biimidazole, 2,2'-bis
(o-chlorophenyl)-4,4'5,5'-tetraphenyl-; and TCTM-HABI, i.e.,
1H-imidazole, 2,5-bis(o-chloro-phenyl)-4-[3,4-dimethoxyp- henyl]-,
dimer, each of which is typically used with a hydrogen donor or
chain transfer agent. Especially preferred initiators of this class
for this invention are ortho-Cl-HABI, i.e., 1,1'-biimidazole,
2,2'-bis(ortho-chlorophenyl)-4,4',5,5'-tetraphenyl-imidazole dimer
and 2,3,5-TCl-HABI, i.e.,
2,2'-bis(2,3,5-trichlorophenyl)-4,4',5,5'-tetraphen-
yl-1,1'-biimidazole.
[0027] The near infrared photosensitizers of this invention are
those having the generic formula shown in Table 1 following the
examples or the specific formula described herein or shown in Table
2.
[0028] As shown in Table 1, the infrared sensitive dye is chosen
from a compound of Formula I wherein substituent A is chosen
from
[0029] (1) a 5-6 membered heterocyclic ring system having 1-3 ring
heteroatoms selected from N which are substituted with H,
C.sub.1-C.sub.6 alkyl, (CH.sub.2).sub.mCO.sub.2H or
(CH.sub.2).sub.mCO.sub.2(C.sub.1-C.su- b.6 alkyl) and a C atom of
the heterocyclic ring system may be substituted with oxygen to form
a carbonyl or enolate anion and m is 0-4;
[0030] (2) A 5-6 membered carbocyclic moiety substituted with H,
C.sub.1-C.sub.6 alkyl wherein a carbon atom of the carbocyclic
moiety may be substituted with oxygen to form a carbonyl or enolate
anion;
[0031] (3) quinoline or isoquinoline wherein the nitrogen is
directly bonded to the carbocyclic moiety of formula I;
[0032] (4) N,N-bisaryl or bis(C.sub.1-C.sub.6 alkyl) or
bisaryl(C.sub.1-C.sub.6 alkyl) amine wherein the aryl group is
chosen from napthyl or phenyl which is unsubstituted or substituted
with substituents chosen from F, Br, Cl, OCH.sub.3, CF.sub.3, OH,
C.sub.1-C.sub.6 alkyl or aryl C.sub.6-C.sub.10, such as phenyl or
naphthyl;
[0033] (5) a heterocyclic ring system having at least one nitrogen
bonded directly to the carbocyclic ring of formula I and a group Z
selected from C, NR.sup.8, O or S wherein R.sup.8 is chosen from H,
C.sub.1-C.sub.6 alkyl, CO.sub.2H or CO.sub.2-C.sub.1-C.sub.6
alkyl;
[0034] substituent D.sub.1 is chosen from a 9-15 membered
heterocyclic system such as a heteroaryl ring system having at
least one heteroatom (U) chosen from NR.sup.3, O, S or PR.sup.3
which is directly bonded to the aryl portion of the heteroaryl ring
system and wherein R.sup.3 is chosen from C.sub.1-C.sub.6 alkyl
which may be unsubstituted or substituted with CO.sub.2II,
SO.sub.3II or salts thereof and wherein the aryl ring may be
unsubstituted or substituted with substituents selected from
OCH.sub.3, CF.sub.3, Br, Cl, F, C.sub.1-C.sub.6 alkyl, OH or
substituent D.sub.1 may be a fused ring heterocyclic system such as
when heterocyclic rings are fused to form a polycyclic
structure;
[0035] substituent D.sub.2 has the identical heterocyclic ring
system as D.sub.1, which may be heteroaryl or fused ring
heterocyclic system, except that when U is NR.sub.3, the nitrogen
is quaterinized to form an amine salt which is neutralized by an
enolate anion from A when A is a substituted pyrimidine like moiety
or by a discrete (non intra-molecular) anion;
[0036] n is chosen from 1-2.
[0037] The near infrared photosensitizers within the scope of this
invention include, but are not limited to, the following dye
compounds as defined in the glossary: DF-15131, DF-15118, DF-1668,
DF-15132, DF-1413, DF-1419, DF-1429, DF-1422, NK-2268, NK-3877,
GW-826, DF-12124, GW-976, GW-436, GW-186, and GW-776. Dye compounds
that are preferred as photosensitizers include, but are not limited
to, the following: DF-15132, NK-3877, KF-634, DF-1668, DF-1413,
DF-15118, DF-15131, GW-826, GW-976, and GW-186. Dye compounds that
are most preferred as photosensitizers according to the invention
are the following: DF-1413, DF-15118, DF-15131, GW-826, GW-976, and
GW-186. The basis for the above preferences is relative efficacy of
the dye as a near IR photosensitizer.
[0038] The solubility characteristics of the dye provide another
basis for preferences in dye selection. In this regard, zwitterion
dyes that are charge neutral are preferred in coating photopolymer
compositions from an organic solvent(s), such as methyl ethyl
ketone or methanol, since these zwitterionic dyes have
significantly higher (better) solubility characteristics in organic
solvents and are less prone toward crystallization of solids in the
compositions during coating and/or use. In some cases, these
zwitterionic dyes can lead to other performance advantages of the
compositions of this invention. For compositions coated from
organic solvents, dyes having the zwitterionic bartituric acid
moiety (i.e., 2-[2,4,6-trioxo-1,3-pyrimidin-5-yl]) or related
zwitterionic moieties are preferred. Such dyes are charge neutral
and do not contain a counterion, such as a halide anion, that is
present in other dyes that are not charge neutral. Dyes within the
scope of the invention having the bartituric acid moiety and which
are preferred on the basis of solubility characteristics include,
but are not limited to, DF-1413, DF-1419, DF-1422, DF-1668,
DF-1429, DF-15118, DF-15131, and DF-15132.
[0039] Dye compounds that were tested (see comparative examples)
and found to be inoperable and which are consequently outside the
scope of the invention include the following: SQS.
[0040] The quantity of photoinitiator system (including
photosensitizer(s) and photoinitiator(s) to comprise the
photoinitiator system) in a photopolymerizable composition of this
invention is typically from 0.5 to 10 parts by weight relative to
the total components, preferably is from about 1 to about 5 parts
by weight relative to the total components, and most preferably is
from about 2 to about 3 parts by weight relative to the total
components. The ratio of photosensitizer(s) to photoinitiator(s) in
parts by weight of the total photoinitiator system of this
invention is typically from about 0.02 to about 1.0, preferably is
from about 0.03 to about 0.5, and most preferably is from about
0.04 to about 0.2.
Chain Transfer Agent
[0041] Hexarylbiimidazole (HABI) photoinitiators are known to those
skilled in the art to be generally ineffective toward initiating
photopolymerization of an ethylenically unsaturated monomer unless
there is present in the photo-polymerizable composition a chain
transfer agent (hydrogen donor). When a suitable chain transfer
agent is present in the composition, then a HABI photoinitiator is
very effective and efficient in initiating the polymerization of
ethylenically unsaturated monomer(s) to afford photopolymerized
photopolymer. For this reason, a suitable chain transfer agent is a
necessary and required component in the photopolymerizable
(photohardenable) compositions of the first embodiment of this
invention. The chain transfer agent generally must be present in an
amount in the range from about 0.1 to about 2 parts by weight based
on the total composition. Preferably, the chain transfer agent is
present in an amount in the range from about 0.5 to about 1.0 parts
by weight based on the total composition.
[0042] In sharp contrast, HABI photoinitiators are known to be
effective during photoimaging in oxidizing a leuco dye to the
corresponding colored dye form to form an image even in the absence
of a chain transfer agent. Thus, for the compositions of the second
embodiment of this invention, a chain transfer agent is not
required since there is effective photoimaging in its absence, but
it is nevertheless an optional component in these compositions.
[0043] Suitable chain transfer agents according to this invention
include, but are not limited to, the following: N-arylglycine, such
as for example, N-phenylglycine; julolidine; N,N-dialkylamino
aromatics, where the alkyl groups are independently C.sub.1-C.sub.6
alkyl, and representative examples include Michler's Ketone, leuco
crystal violet and other aminotriarylmethane leuco dyes, and
2,6-diisopropyl-N,N-dimethy- laniline; 2-mercaptobenzoxazole;
1,1-dimethyl-3,5-diketocyclohexane, or organic thiols, e.g.,
2-mercaptobenzothiazole; 2-mercaptobenzoxazole;
2-mercaptobenzimidazole; pentaerythriotol tetrakis
(mercaptoacetate); 4-acetamidothiophenol; mercaptosuccinic acid;
dodecanethiol; beta-mercaptoethanol; beta-mercaptoethanol; or other
organic thiol. Preferred chain transfer agents for this invention
include N-phenylglycine, 2,6-diisopropyl-N,N-dimethylaniline, and
julolidine.
Photopolymerizable Material
[0044] The first embodiment of this invention involves compositions
that contain a photopolymerizable material that undergoes
photopolymerization upon exposure to near infrared actinic
radiation to afford a polymerized photopolymer. In general, the
invention scope is considered to include any photopolymer systems
known in the art which undergo photopolymerization upon exposure to
actinic radiation to afford polymerized photopolymer. Suitable
photopolymer systems include, but are not limited to, negative
working systems in which at least one ethlenically unsaturated
monomer is photopolymerized to photopolymerized photopolymer,
negative working systems, such as poly(vinyl cinnamate) that
involve cycloaddition reactions to afford photopolymerized
photopolymer, and positive working systems, such as those of the
diazaquinone type that afford acid functionality that is
developable in aqueous alkali upon exposure to actinic raidation.
Discussion of these different photopolymer systems can be found in
many references, such as, for example, Photoreactive Polymers The
Science and Technology of Resists, by Arnost Reiser, John Wiley
& Sons, New York, 1989.
[0045] The preferred choice for the photopolymerizable material is
an ethylenically unsaturated monomer. Suitable monomers useful
herein are well known in the prior art and typically undergo free
radical initiated polymerization. In the compositions of this
invention that contain an ethylenically unsaturated monomer, the
composition contains at least one or a mixture of such components.
In general, preferred monomers for photopolymer applications have
boiling points greater than 100.degree. C. (at 760 mm Hg, 1
atmosphere), more preferably, greater than 150.degree. C. (at 760
mm Hg, 1 atmosphere). Numerous unsaturated monomers polymerizable
by free-radical initiated polymerization and useful in
photopolymerizable compositions are known to those skilled in the
art.
[0046] The monomer provides the capability of the photopolymer
coating composition to photopolymerize and contributes to overall
properties. In order to effectively do so, the monomer should
contain at least one ethylenically unsaturated group capable of
undergoing polymerization on exposure to actinic radiation.
[0047] The preferred monomeric compounds are polyfunctional, but
monofunctional monomers, such as (meth)acrylate esters of
polycaprolactone, can also be used. Suitable monomers which can be
used as the sole monomer or in combination with others include the
following: diethylene glycol diacrylate, tripropylene glycol
diacrylate, trimethylolpropane triacrylate, pentaerythritol
triacrylate, ethoxylated trimethylolpropane tri(meth)acrylate,
propoxylated trimethylolpropane tri(meth)acrylate and similar
compounds as disclosed in U.S. Pat. No. 3,380,831, triethylene
glycol dimethacrylate, bisphenol-A di(meth)-acrylate,
di-(2-methacryloxyethyl) ether of bisphenol-A,
di-(3-acryloxy-2-hydroxypropyl) ether of bisphenol-A,
di-(2-acryloxyethyl)ether of bisphenol-A,
di-(3-methacryloxy-2-hydroxypro- pyl) ether of
tetrachloro-bisphenol-A, di-(2-methacryloxyethyl) ether of
tetrachloro-bisphenol-A, di-(3-methacryloxy-2-hydroxypropyl) ether
of tetrabromo-bisphenol-A, di-(2-methacryloxyethyl) ether of
tetrabromo-bisphenol-A, ethoxylated bisphenol-A di(meth)acrylate,
propoxylated bisphenol-A di(meth)-acrylate, diacrylate of
bisphenol-A diglycidyl ether and poly-caprolactone diacrylate.
[0048] A particularly preferred class of monomers or comonomers is
tripropylene glycol diacrylate, trimethylolpropane triacrylate,
ethoxylated trimethylolpropane triacrylate, propoxylated
trimethylolpropane triacrylate, ethoxylated Bisphenol A
dimethacrylate, and triethylene glycol dimethacrylate. The
polymerizable material can be present in any amount from 0 to about
70 weight percent. For the first embodiment, it is normally present
in an amount from 20 to 70 weight percent.
Binder Polymers
[0049] The compositions of this invention most often preferably
contain one or more binder polymer as optional component(s).
[0050] The binder polymers present in the compositions of this
invention are not required to but preferably do contain acid
functionality for aqueous processability (aqueous development),
which is preferably achieved by incorporating one or more
carboxyl-containing comonomers into the binder polymer. Preferred
polymers for the instant invention also contain styrene as a
comonomer. Suitable polymers for the instant invention contain 0-50
weight percent styrene as comonomer, have an acid number in the
range 90-160, have a molecular weight (weight average) in the range
20,000-300,000, and have a glass transition temperature in the
range 50-120.degree. C. Preferably, the binders contain 5-40%
styrene as comonomer, have an acid number in the range 110-140,
have a molecular weight (weight average) in the range
40,000-200,000, and have a glass transition temperature in the
range 60-110.degree. C. Most preferably, the polymers contain
10-30% styrene as comonomer, have an acid number in the range
125-135, have a molecular weight (weight average) in the range
60,000-100,000, and have a glass transition temperature in the
range 70-100.degree. C.
[0051] Preferred polymer binders are acid-containing copolymers or
homopolymers comprised of at least one acid-containing monomer of
structural unit: 1
[0052] in which R.sub.a is H, phenyl, or alkyl; R.sub.b is
CO.sub.2R.sub.c, SO.sub.3R.sub.d, or other acidic functional group;
and R.sub.c and R.sub.d are H or alkyl, which is unsubstituted or
hydroxyl-substituted. Alkyl groups can contain one to twelve carbon
atoms and preferably one to eight. Comonomers, which are suitable
for forming the binder copolymer, are styrene and unsaturated
carboxylic acids and their derivatives, such as (meth)acrylic acid
and (meth)acrylates. Acrylic acid, methacrylic acid, methyl
methacrylate, styrene, ethyl acrylate, ethyl methacrylate, butyl
methacrylate, butyl acrylate, maleic anhydride, 2-hydroxyethyl
methacrylate, and 2-ethylhexyl methacrylate are preferred.
[0053] Suitable binder copolymers can be formed by direct
copolymerization of one or more ethylenically unsaturated
dicarboxylic acid anhydrides, or the corresponding alkyl diesters,
with one or more of the above comonomers.
[0054] Suitable ethylenically unsaturated dicarboxylic acid
anhydrides are, for example, maleic anhydride, itaconic acid
anhydride and citraconic acid anhydride and alkyl diesters such as
the diisobutyl ester of maleic anhydride. The copolymer binder
containing acid anhydride functionality can be reacted with primary
aliphatic or aromatic amines to produce acid and amide
functionality.
[0055] A preferred acid-containing binder for aqueous
processability in use as well as aqueous coatability in dry film
manufacture is a carboxylic acid-containing copolymer, such as
those disclosed in U.S. Pat. Nos. 3,458,311 and 4,273,857, and
which can be prepared by any of the addition polymerization
techniques known to those skilled in the art such as described
therein. The level of carboxylic acid groups is determined for a
given composition by optimizing the amount needed for good
development in aqueous alkaline developer.
[0056] When a negative-working aqueous processable photoresist,
solder mask, proofing film, or flexographic plate is laminated to a
substrate and photoprinted, development of the photoresist, solder
mask, proofing film, or flexographic plate composition may require
that the binder material should contain sufficient carboxylic acid
groups to render the photoresist, solder mask, proofing film, or
flexographic plate coating composition processable in aqueous
alkaline developer. The photoresist, solder mask, proofing film, or
flexographic plate coating layer will be removed in portions which
are not exposed to radiation but will be substantially unaffected
in exposed portions during development by aqueous alkaline liquids
such as wholly aqueous solutions containing 1% sodium carbonate by
weight at a temperature of 30.degree. C. for 1-2 minutes.
[0057] For those applications where the development is effected
using solvent development with an organic liquid developer or
semiaqueous development with a liquid mixture containing water and
organic solvent(s), it is not required that the binder(s) have
acid-containing functionality, such as carboxylic acid
functionality. In these cases, all of the comonomers for the
binder(s) can be non-acid containing comonomers.
Leuco Dye
[0058] The leuco form of the dye which comprises one component of a
photoimaging composition of the present invention is the reduced
form of the dye having one or two hydrogen atoms, the removal of
which together with an additional electron in certain cases
produces the dye. Such dyes have been described, for example, in
U.S. Pat. No. 3,445,234, column 2, line 49 to column 8, line 55.
The following classes are included:
[0059] (a) aminotriarylmethanes
[0060] (b) aminoxanthenes
[0061] (c) aminothioxanthenes
[0062] (d) amino-9, 10-dihydroacridines
[0063] (e) aminophenoxazines
[0064] (f) aminophenothiazines
[0065] (g) aminodihydrophenazines
[0066] (h) aminodiphenylmethanes
[0067] (i) leuco indamines
[0068] (j) aminohydrocinnamic acids (cyanoethanes, leuco
methines)
[0069] (k) hydrazines
[0070] (l) leuco indigoid dyes
[0071] (m) amino-2,3-dihydroanthraquinones
[0072] (n) tetrahalo-p,p'-biphenols
[0073] (1) 2(p-hydroxyphenyl)-4,5-diphenylimidazoles
[0074] (p) phenethylanilines
[0075] Of these leuco forms, (a) through (i) form the dye by losing
one hydrogen atom, while the leuco forms (j) through (p) lose two
hydrogen atoms to produce the parent dye. Aminotriarylmethanes are
preferred. A general preferred aminotriarylmethane class is that of
the acid salts of aminotriarylmethanes wherein at least two of the
aryl groups are phenyl groups having (a) an ReRfN-substituent in
the position para to the bond to the methane carbon atom wherein
R.sub.e and R.sub.f are each groups selected from hydrogen, C.sub.1
to C.sub.10 alkyl, 2-hydroxyethyl, 2-cyano-ethyl, or benzyl and,
optionally, (b) a group ortho to the methane carbon atom which is
selected from lower alkyl (C is 1 to 4), lower alkoxy (C is 1 to
4), fluorine, chlorine or bromine; and the third aryl group may be
the same as or different from the first two, and when different is
selected from
[0076] (a) Phenyl which can be substituted with lower alkyl, lower
alkoxy, chloro, diphenylamino, cyano, nitro, hydroxy, fluoro or
bromo;
[0077] (b) Naphthyl which can be substituted with amino, di-lower
alkylamino, alkylamino;
[0078] (c) Pyridyl which can be substituted with alkyl;
[0079] (d) Quinolyl;
[0080] (e) Indolinylidene which can be substituted with alkyl.
[0081] Preferably, R.sub.1 and R.sub.2 are hydrogen or alkyl of 1-4
carbon atoms. Leuco dye is present in 0.1 to 5.0 percent by weight
of solids in the photoimaging composition.
[0082] With the leuco form of dyes which have amino or substituted
amino groups within the dye structure and which are characterized
as cationic dyes, an amine salt-forming mineral acid, organic acid,
or an acid from a compound supplying acid is employed. The amount
of acid usually varies from 0.33 mol to 1 mol per mol of amino
nitrogen in the dye. The preferred quantity of acid is about 0.5 to
0.9 mol per mol of amino nitrogen. Representative acids which form
the required amine salts are hydrochloric, hydrobromic, sulfuric,
phosphoric, acetic, oxalic, p-toluenesulfonic, trichloroacetic,
trifluoroacetic and perfluoroheptanoic acid. Other acids such as
acids in the "Lewis" sense or acid sources which may be employed in
the presence of water or moisture include zinc chloride, zinc
bromide, and ferric chloride. Representative leuco dye salts
include tris-(4-diethylamino-o-tolyl) methane zinc chloride,
tris-4-diethylamino-o-tolyl) methane oxalate,
tris-(4-diethylamino-o-tolyl) methane p-toluene-sulfonate and the
like.
[0083] Aminotriarylmethanes and salts thereof are preferred leuco
dyes in this invention. Especially preferred aminotriarylmethane
leuco dyes according to this invention include, but are not limited
to, LCV, LECV, LPCV, LBCV, LV-1, LV-2, LV-3, aminotriarylmethane
leuco dyes having different alkyl substituents bonded to the amino
moieties wherein each alkyl group is independently selected from
C.sub.1-C.sub.4 alkyl, and aminotriarylmethane leuco dyes
comprising any of the preceding named structures that are further
substituted with one or more alkyl groups on the aryl rings wherein
the latter alkyl groups are independenly selected from
C.sub.1-C.sub.3 alkyl. The most preferred aminotriarylmethane leuco
dyes according to this invention are LCV, LECV, LV-1, LV-2, and
LV-3. The leuco dye can be present in the compositions in any
amount from 0 to about 20 weight percent. In embodiment 2, it will
normally be present in an amount from 0.5 to about 10 weight
percent.
Optional Ingredients
[0084] Other compounds conventionally added to proofing films,
flexographic printing plates, photoresist, solder mask, and other
related photopolymer compositions may also be present in the
coating to modify the physical properties of the film. Such
components include: adhesion modifiers, thermal stabilizers, a
printout image system comprising colorants such as dyes and
pigments, viscosity control agents, coating aids, wetting agents,
surfactants, release agents, fillers, crosslinking agents, and the
like.
[0085] Examples of suitable printout image systems are the
following: 2,2'-bis(o-chlorophenyl)-4,4',5,5'-tetraphenyl-1,1
'-biimidazole and Leuco Crystal Violet (LCV);
1,2-dibromotetrachloroethane and LCV; tribromomethyl phenylsulfone
(BMPS) and LCV; and 2,3-dibromo-3-phenylprop- iophenone (BPP) and
LCV.
[0086] Some heterocyclic compounds improve adhesion of the coating
to copper-clad substrates or prevent residue formation during
processing in a resist or related application. Suitable
heterocyclic components include materials such as those disclosed
in Hurley et al., U.S. Pat. No. 3,622,334, Jones, U.S. Pat. No.
3,645,772, and Weed, U.S. Pat. No. 4,710,262. Preferred
heterocyclic components include benzotriazole,
5-chloro-benzotriazole, 1-chloro-benzotriazole, 4-and
5-carboxy-benzotriazole, 1-hydroxy-benzotriazole,
2-mercapto-benzoxazole, 1 H-1,2,4-triazole-3-thiol,
5-amino-1,3,4-thiodiazole-2-thiol, and mercapto-benzimidazole.
[0087] Thermal polymerization inhibitors that can be used in the
coating compositions are: p-methoxyphenol, hydroquinone, alkyl- and
aryl-substituted hydroquinones and quinones, tert-butyl catechol,
2,6-di-tert-butyl-p-cresol, and phenothiazine. Also useful for
thermal polymerization inhibitors are the nitroso compositions
disclosed in U.S. 4,168,982.
[0088] Various dyes and pigments may be added to increase the
visibility of the photopolymer image. Any colorant used, however,
should preferably be transparent to the actinic radiation.
Representative dyes include leuco crystal violet, Victoria green
dye, Victoria blue dye, and Neozapon red dye.
[0089] In the case of a photoimageable solder mask composition,
there will be in addition to the key components listed above a
crosslinking agent present to provide for curing of the imaged
resist. Suitable crosslinking agents include an adduct of a
polyisocyanate compound and a isocyanate group blocking agent, and
formaldehyde condensation resins with melamines, ureas,
benzguanidines, and the like.
[0090] A suitable photodeactivation compound can be employed in
this invention. Preferred are various quinone compounds. A quinone
redox couple useful in the photoimaging composition is described in
U.S. Pat. No. 3,658,543, column 9, lines 1 to 46, incorporated by
reference. Preferred oxidants include 9,10-phenanthrenequinone
alone or in admixture with 1,6-and 1,8-pyrenequinone which absorb
principally in the 430 to 550 nm region. The reductant component of
the redox couple is 100 to 10 percent of an acyl ester of
triethanolamine of the formula: 2
[0091] where R.sub.g is alkyl of 1 to 4 carbon atoms, and 0 to 90
percent of a C.sub.1, to C.sub.4 alkyl ester of nitrioltriacetic
acid or of 3,3',3"-nitrilotripropionic acid. Triethanolamine
triacetate and dibenzylethanolamine acetate are preferred reductant
components. The molar ratios of oxidants to biimidazole used ranges
from 0.01:1 to 2:1, preferably 0.2:1 to 0.6:1. The molar ratios of
reductant biimidazole used ranges from about 1:1 to about 90:1,
preferably 10:1 to 20:1.
Materials of Construction
[0092] Any of the support films known for use as such for a
photoimageable coating can be used as a temporary support for
coating the photoimageable material onto in the application of the
present invention. The temporary support film, which preferably has
a high degree of dimensional stability to temperature changes, may
be chosen from a wide variety of polyamides, polyolefins,
polyesters, vinyl polymers, and cellulose esters, and may have a
thickness of from about 6 to 200 microns. A particularly suitable
support film is polyethylene terephthalate having a thickness of
about 25 microns.
[0093] In a photoimageable film it is necessary or at least highly
desirable to protect the photosensitive layer by a removable cover
film in order to prevent blocking when it is stored in a roll form.
The protective cover film is removed prior to lamination of the
photoimageable element to a substrate.
[0094] The protective cover film may be selected from the same
group of high polymer films described for the temporary support
film, supra, and may have the same wide range of thicknesses;
however, it is preferable to use a cover sheet that is relatively
flexible under lamination conditions. A cover sheet of 25 microns
thick polyethylene or polypropylene is especially suitable.
Preferred Ranges
[0095] The preferred ranges of components for the
photopolymerizable compositions of the first embodiment of this
invention are about 30 to 80 parts by weight of the polymer(s)
(binder(s), polymeric binder(s)); about 10 to 50 parts by weight of
photopolymerizable material(s); and about 0.5 to 10 parts by weight
of the photoinitiator system comprised of a near IR photosensitizer
and a HABI photoinitiator. The preferred ranges of components for
the photoimageable (2nd) embodiment of this invention are 0 to
about 70 parts by weight of polymers, about 0.1 to about 10 parts
by weight of leuco dye(s), and about 0.5 to 10 parts by weight of
the photoinitiator system comprised of a near IR photosensitizer
and a HABI photoinitiator. The preferred ratio range of
photosensitizer to photoinitiator on a parts by weight basis is
from about 0.04 to about 0.2.
[0096] The thickness of the photoimageable and/or
photopolymerizable (photohardenable) layer will depend on the type
of processing being done and is not limited.
Manufacturing Process
[0097] The process of formation of a dry film is relatively simple
and direct. The stable liquid photoimageable and/or
photopolymerizable composition(s) of the present invention is
coated onto a substrate which may be permanent or temporary.
Various methods of coating can be employed which are well known in
the art.
[0098] Substantially all solvent(s) in the liquid composition is
removed which results in a dry film. Since a relatively high solids
content is present in the liquid, under preferred conditions it is
considered that a relatively small amount of liquid has to be
removed in forming a dry film.
PROCESS OF USE
[0099] The photoimageable and/or photopolymerizable compositions of
this invention may be used to prepare photoresists, soldermasks,
printing plates, and proofing products. These compositions are
applied to a substrate by coating or lamination if a dry film as
described above is prepared. After drying, the coating is imagewise
exposed to actinic radiation, generally through a process negative
or positive transparency after a draw-down time of 30 seconds to 2
minutes. The transparency is an image bearing transparency
consisting solely of substantially opaque and substantially
transparent areas where the opaque areas are substantially of the
same optical density. The compositions used in the process of the
invention generally exhibit their maximum sensitivity in the near
infrared (near-IR) range, therefore the radiation source should
furnish an effective amount of this type of radiation. Suitable
radiation sources include diode lasers which emit in the near-IR
range. The radiation exposure time can vary from fractions of a
second to minutes depending on the intensity, type of radiation
source used and its distance from the
photoimageable/photopolymerizable layer and the type of
photoimageable/photopolymerizable layer. In general exposure times
range from 10 seconds to 10 minutes or more using standard
non-laser commercial radiation sources and can be much shorter
(milliseconds or less) using laser sources.
[0100] Following imagewise exposure to form imaged and non-imaged
areas in the photoimageable/photopolymerizable composition, and
removal of the cover sheet, if present, the exposed layer is
developed to form an image on the first substrate. Developing of
the exposed layer having imaged and non-imaged areas to form an
image on the first substrate can be a dry development step, as in
certain proofing applications, or it can be a wet development step,
as in other proofing applications and as typical for photoresist,
solder mask, and flexographic printing plate applications. The
exposed layer may be developed using an aqueous alkaline developer,
a semiaqueous developer, or a solvent developer which will remove
the non-imaged areas leaving a relief image. If the first substrate
is a copper-clad epoxy glass substrate, then the image formed is a
resist image which may be used as a mask for etching or plating the
copper exposed areas of the first substrate. If the first substrate
is a metal substrate, such as anodized aluminum, then a printing
plate results. The photoimageable layer may be pigmented resulting
in a proofing product after wash-off development.
[0101] The exposed layer may also be developed by toning with a
toning foil or film or by dusting with a powdered toner. Useful
toning films are described in Froehlich, U.S. Pat. No. 3,625,014,
issued Jul. 6, 1987. The films, which are comprised of a support
and a low cohesive strength, pigmented polymer layer, are laminated
to the exposed layer having imaged and non-imaged areas. The
support is peeled off along with the pigmented polymer adjacent the
imaged areas on the first substrate. In general, it is necessary to
apply the toning film more slowly than usual lamination rates and
some experimentation may be required to determine optimum rates and
temperatures for laminating each different toning film.
[0102] Dry non-electroscopic toners, their method of production, as
well as improved surface coatings, are well known in the art as,
for example, in Chu and Manger, U.S. Pat. No. 3,620,726; Gray, U.S.
Pat. No. 3,909,382; Fickes et al., U.S. Pat. No. 4,215,193; Fickes,
U.S. Pat. No. 4,397,941; and Matrick, U.S. Pat. No. 4,546,072. The
toner is applied to the exposed layer having non-tacky, imaged
areas and tacky non-imaged areas. Excess toner is wiped off,
providing a toner image on the first substrate.
[0103] The exposed layer having imaged and non-imaged areas may
also be developed by peel-apart development. In this embodiment the
photoimageable layer may be pigmented. A second substrate may be
laminated to the photoimageable layer prior to the exposure step or
after formation of the imaged and non-imaged areas in the exposed
layer. The second substrate is then peeled off, resulting in the
imaged areas remaining on the first substrate and the non-imaged
areas being removed on the second substrate. If the
photo-imageable/photopolymerizable layer is unpigmented, the tacky
non-imaged areas that are removed with the second substrate may be
treated with dry particulate toners or toning films as described
above.
DEFINITIONS
Effective Photopolymerization
[0104] Photopolymerization done under the compositions and
processes of this invention is defined to be effective when the
compositions, upon imagewise exposure to actinic radiation, are
substantially unaffected by an aqueous (developer) solution (1%
sodium carbonate by weight), a semiaqueous (developer) solution, or
a solvent (developer) solution at a temperature of 30.degree. C.
for 1-2 minutes in portions exposed to actinic radiation but
removed in portions not exposed to actinic radiation.
Effective Photoimaging
[0105] Photoimaging done under the compositions and processes of
this invention, when not involving photopolymerization, is defined
to be effective when the compositions, upon imagewise exposure to
actinic radiation, undergo an increase in optical density of at
least 0.2 optical density units in portions exposed to actinic
radiation but undergo an increase of at most 0.1 optical density
units in portions not exposed to actinic radiation. For
photoimaging involving photopolymerization and washout, effective
photoimaging is defined in the same manner as effective
photopolymerization as given above.
Near Infrared (Near IR) Sensitive Dye
[0106] This is a dye which absorbs in the near infrared (near-IR)
range (.about.770-1500 nm) of the electromagnetic spectrum and
which is capable of activating a HABI photoinitiator to initiate
photopolymerization of a photopolymerizable material and/or to
initiate photoimaging of a photoimageable material via formation of
a colored dye from a colorless or lightly colored dye precursor. An
example of such color formation is the oxidation of a leuco dye to
the colored dye form to generate the photoimage.
A Pair of Corresponding Heterocyclic Ring Structures
[0107] A pair of corresponding heterocyclic ring structures is
defined to be two heterocyclic ring structures having the same
number of atoms of each type and in which each atom is bonded to
the same number and types of other atoms in each paired structure.
The only difference between pairs is that some of the chemical
bonds are different between the paired members (C-C single bond
versus a C.dbd.C double bond) and that a heteroatom is quatemized
in one member (D.sub.2) of a given pair and not quaternized in the
other member (D.sub.1) of the given pair. Some illustrative
examples of D.sub.1 and D.sub.2 paired members of different
heterocyclic ring structures are given below in Table 2.
GLOSSARY
Near IR Dyes Within Invention Scope
DF-1413
[0108]
2-[2-[2-[2,4,6-trioxo-1,3-pyrimidin-5-yl]-3-[2-(1,3-dihydro-1-ethyl-
-3,3-dimethyl-2H-indol-2-ylidene)-ethylidene]-1-cyclopenten-1-yl]-ethenyl]-
-1-ethyl-3,3-dimethyl-3H-indolium, inner salt
DF-1419
[0109]
2-[2-[2-[2,4,6-trioxo-1,3-pyrimidin-5-yl]-3-[2-(1-ethyl-2(1H)quinol-
ylidene)-ethylidene]-1-cyclopenten-1-yl]-ethenyl]-1-ethyl-quinolium,inner
salt
DF-1429
[0110]
2-[2-[2-[2,4,6-trioxo-1,3-pyrimidin-5-yl]-3-[2-(1,3-dihydro-1,3,3-t-
rimethyl-5-methoxy-2H-indol-2-ylidene)-ethylidene]-1-cyclopenten-1-yl]-eth-
enyl]-1,3,3-trimethyl-5-methoxy-3H-indolium, inner salt
DF-1422
[0111]
2-[2-[2-[2,4,6-trioxo-1,3-pyrimidin-5-yl]-3-[2-(1,3-dihydro-1,1,3-t-
rimethyl-2H-benz[e]indol-2-ylidene)-ethylidene]-1-cyclopenten-1-yl]-etheny-
l]-1,3-dihydro-1,1,3-trimethyl-2H-benz[e]indolium, inner salt
DF-1668
[0112]
2-[2-[2-[2,4,6-trioxo-1,3-pyrimidin-5-yl]-3-[1-ethyl-naphtho[1,2-d]-
thiazol-2(1H)-ylidene)-ethylidene]-1-cyclopenten-1-yl]-ethenyl]-1-ethyl-2H-
-naphtho [1,2-d]thiazolium, inner salt
DF-12124
[0113]
2-[2-[2-piperidino-3-[2-(1-ethyl-1,3-dihydrobenzothiazol-2-ylidene)-
-ethylidene]-1-cyclopenten-1-yl]ethenyl]-1-ethylbenzothiazolium,
n-butyltriphenylboron salt
DF-15118
[0114]
2-[2-[2-[2,4,6-trioxo-1,3-pyrimidin-5-yl]-3-[3-ethyl-6-methoxy-2(3H-
)benzothiazolylidene)-ethylidene]-1-cyclopenten-1-yl]-ethenyl]-3-ethyl-6-m-
ethoxy-2(3H)-benzothiazolium, inner salt
DF-15131
[0115]
2-[2-[2-[2,4,6-trioxo-1,3-pyrimidin-5-yl]-3-[3-ethyl-2(3H)benzothia-
zolylidene)-ethylidene]-1-cyclopenten-1-yl]-ethenyl]-3-ethyl-2(3H)-benzoth-
iazolium, inner salt
DF-15132
[0116]
2-[2-[2-[2,4,6-trioxo-1,3-pyrimidin-5-yl]-3-[3-(sulfopropyl)-5-trif-
luoro-methyl-2(3H)benzothiazolylidene)-ethylidene]-1-cyclopenten-1-yl]-eth-
enyl]-3-(3-sulfopropyl)-5-trifluoromethyl-2(3H)-benzothiazolium,
bis-triethylammonium salt
GW-826
[0117]
2-[2-[2-2-piperdino-3-[2-(1-ethyl-1,3-dihydrobenzothiazol-2-ylidene-
)-ethylidene]-1-cyclopenten-1-yl]ethenyl]-1-ethylbenzothiazolium,
bromide salt
GW-436
[0118]
2-[2-[2-2-morpholino-3-[2-(1-ethyl-1,3-dihydrobenzothiazol-2-yliden-
e)-ethylidene]-1-cyclohexen-1-yl]ethenyl]-1-ethylbenzothiazolium,
bromide salt
GW-776
[0119]
2-[2-[2-4-carboethoxyhexahydropyrazino-3-[2-(1-ethyl-1,3-dihydroben-
zothiazol-2-ylidene)-ethylidene]-1-cyclopenten-1-yl]ethenyl]-1-ethylbenzot-
hiazolium, bromide salt
GW-976
[0120] 2-[2-[2-(2
aza-1,2,3,4-tetrahydronaphthalenyl)-3-[2-(1-ethyl-1,3-di-
hydrobenzo-thiazol-2-ylidene)-ethylidene]-1-cyclohexen-1-yl]ethenyl]-1-eth-
ylbenzothiazolium, bromide salt
GW-186
[0121]
2-[2-[2-4-methylhexahydropyrazino-3-[2-(1-ethyl-1,3-dihydrobenzothi-
azol-2-ylidene)-ethylidene]-1-cyclohexen-1-yl]ethenyl]-1-ethylbenzothiazol-
ium, tetrafluoroborate salt
NK-2268
[0122]
2-[2-[2-2-diphenylamino-3-[2-(1-ethyl-1,3-dihydrobenzothiazol-2-yli-
dene)-ethylidene]-1-cyclopenten-1-yl]ethenyl]-1-ethylbenzothiazolium,
perchlorate salt
NK-3877
[0123]
2-[2-[2-diphenylamino-3-[2-(1-ethyl-6-methoxy-1,3-dihydrobenzothiaz-
ol-2-ylidene)-ethylidene]-1-cyclopenten-1-yl]ethenyl]-1-ethyl-6-methoxy-be-
nzothiazo-lium, perchlorate salt
HABIs
[0124]
1 CDM-HABI 2-(o-chlorophenyl)-4,5-bis(m-methoxyphenyl)- imidazole
dimer o-Cl-HABI 2,2'-bis(o-chlorophenyl)-4,4',- 5,5'-tetraphenyl-
1,1'-biimidazole (CAS No. 1707-68-2) 2,3,5-TCl-HABI
2,2'-bis(2,3,5-trichlorophenyl)-4,4',5,5'-
tetraphenyl-1,1'-biimidazole or 1,1'-Bi-1H-imidazole,
4,4',5,5'-tetraphenyl-2.2'- bis(2,3,5-trichlorophenyl)- (CA Index
Name, CAS No. 154482-21-0) TCTM-HABI 1H-imidazole,
2,5-bis(o-chloro-phenyl)-4-[3,4- dimethoxyphenyl]-, dimer
Leuco Dyes
[0125]
2 LBCV Leuco butyl crystal violet; the formal chemical name is
tris(N,N-dibutylaminophenyl)methane. LCV Leuco crystal violet; the
formal chemical name is tris(N,N-dimethylaminophenyl)- methane.
LECV Leuco ethyl crystal violet; the formal chemical name is
tris(N,N-diethylaminophenyl)methane. LPCV Leuco propyl crystal
violet; the formal chemical name is
tris(N,N-di-n-propylaminophenyl)methane. LV-1
Bis(4-N,N-diethylaminophenyl)(2-methyl-4-N,N-
diethylaminophenyl)methane. LV-2 (4-N,N-Diethylaminophenyl)bis(2-m-
ethyl-4-N,N- diethylaminophenyl)methane. LV-3
Tris(2-methyl-4-N,N-diethylaminophenyl)methane. TMPEOTA Ethoxylated
trimethylolpropane triacrylate (= polyoxyethylated
trimethylolpropane triacrylate) TMPTA Trimethylolpropane
triacrylate
Other Components
Name of Chain Transfer Agent(s)
[0126]
3 N--PhGly N-Phenylglycine Jul Julolidine DIDMA
2,6-Diisopropyl-N,N-dimethylaniline Binder Polymer MMA/EA/MAA
(44/35/21 wt. %) where MMA = methyl methacrylate EA = ethyl
acrylate MAA = methacrylic acid PET Polyethylene terephthalate
(Mylar .RTM. film, DuPont, Wilmington, DE)
EXAMPLES
[0127] The invention will now be illustrated, but not limited, by
the following examples. Some of the examples as shown in Table 2
(i.e., DF-1429) were less efficient as photochemical
sensitizers.
Example 1
[0128] A few of the near IR dyes mentioned in this disclosure are
available from commercial sources. These dyes and the commercial
source information are given below.
4 Dye Commercial Supplier GW-826 Preferred Chemicals Allied-Signal,
Inc. P. O. Box 1053 101 Columbia Road Morristown, JR 07962-1053
NK-2268 Nippon Kankoh-Shikiso Kenyusho Ltd., Okayama, Japan
Example 2
2-[2-[2-[2,4,6-trioxo-1,3-pyrimidin-5-yl]-3-[2-(1,3-dihydro-1-ethyl-3,3-di-
methyl-2H-indol-2-ylidene)-ethylidene]-1-cyclopenten-1-yl]-ethenyl]-1-ethy-
l-3,3-dimethyl-3H-indolium. inner salt (DF-1413)
[0129] The title compound was prepared as follows:
3-ethyl-1,1,2-trimethyl- indolenium iodide (3.15 g, 0.01 mol) and
(5-(2,5-bis-anilinomethylene)cycl- opentyllidene-1,3-dimethyl
barbituric acid ("Compound B") (2.13 g,0.005 mol) were mixed with
30 mL dimethylformamide. Triethylamine (1.151 g, 0.015 mol) was
added and the mixture heated to 100-103.degree. C. for 15 min. The
mixture was cooled to room temperature and poured into 300 mL of
stirred ethyl ether. The mixture was chilled, filtered, and the
residue reslurried in ether. After filtering and air drying, 2.22 g
of blue-violet crystals were obtained, mp 245-247.degree. C.,
Amax(methanol)=780 (e=292,000).
[0130] The reactants were prepared as follows:
3-Ethyl-1,1,2-trimethylindolenium iodide
[0131] 1,1,2-Trimethylindolenine (22.71 g, 0.143 mol) and
iodoethane (24.50 g, 0.157 mol) were dissolved in 32 mL ethyl
acetate and heated to reflux for 3.5 hrs. The reaction mixture
cooled to room temperature and the resulting precipitate collected
by filtration. The material was washed with acetone until the
washes were colorless. After drying, the yield was 16.33 g.
Recrystallization from isopropanol yielded 15.93 g.
Compound B
[0132] 5-Cyclopentylidene-1,3-dimethylbarbituric acid ("Compound
A") (13.32 g, 0.06 mol) and ethyl isoformanilide (17.9 g, 0.12 mol)
were dissolved in 40 mL dimethylformamide and heated to 123.degree.
C. for 50 min. After cooling to room temperature, 40 mL methanol
was added and the entire mixture cooled to -5.degree. C. The
product was collected by filtration and reslurried in methanol.
After filtration and air-drying, the yield of Compound B was 12.02
g, mp>350.degree. C., max=545 (e=73,300).
Compound A
[0133] 1,3-Dimethylbarbituric acid (23.4 g, 0.15 mol),
cyclopentanone (12.6 g, 0.15 mol), ammonium acetate (3.6 g, 0.047
mol), 6 mL acetic acid, and 100 mL toluene were heated to reflux
for 6 hours. After cooling to room temperature, 100 mL water were
added and the mixture stirred for 30 min. The layers were separated
and the organic phase washed twice with 100 mL water. After drying
the organic phase over sodium sulfate, the toluene was removed by
rotary evaporation and the residue recrystallized from 95% ethanol
to give 23.68 g white crystals of Compound A, mp 109.degree. C.
Example 3
[0134]
2-[2-[2-[2,4,6-trioxo-1,3-pyrimidin-5-yl]-3-]2-(1-ethyl-2(1H)guinol-
ylidene)-ethylidene]-1-cyclopenten-1-yl]-ethenyl-1-ethyl-quinolium,inner
salt (DF-1419)
[0135] The title compound was prepared as follows:
1-ethyl-2-methylquinoli- nium tosylate (3.43 g, 0.01 mol) and
Compound B (2.14 g, 0.005 mol) were mixed with 30 mL
dimethylformamide. Triethylamine (1.15 g, 0.015 mol) was added and
the mixture heated to 100.degree. C. for 25 min. The mixture was
cooled to 10.degree. C., filtered, and washed with acetone. The
product was slurried in acetone, filtered, and dried to yield 2.26
g of copper-colored crystals, mp280.degree. C., max(methanol)=880
(e=166,000). Absorption at 485 nm indicates the presence of some
half-adduct.
[0136] The reactants were prepared as follows: Compound B was made
as above and 1-ethyl-2-methyl quinolinium tosylate was prepared as
below: quinaldine (7.15 g, 0.05 mol) and ethyl tosylate (10 g, 0.05
mol) were heated in 20 mL o-xylene to 144.degree. C. for 6.25 hrs.
When the mixture was cooled to <60.degree. C., acetone was
added. After cooling to room temperature, the mixture was filtered
and the crude product slurried three times in acetone to yield,
after filtering and drying, 8.98 g reddish solid, mp 150.degree.
C.
Example 4
2-[2-[2-[2,4,6-trioxo-1,3-pyrimidin-5-yl]-3-[2-(1,3-dihydro-1,1,3-trimethy-
l-2H-benz[e]indol-2-ylidene)-ethylidene]-1-cyclopenten-1-yl]-ethenyl]-1,3--
dihydro-1,1,3-trimethyl-2H-benz[e]indolium, inner salt
(DF-1422)
[0137] The title compound was prepared as follows:
1,1,2,3-tetramethyl-1H-- benz(e)indolium tosylate (7.9 g, 0.02 mol)
and Compound B (4.28 g, 0.01 mol) were mixed with 30 mL
dimethylformamide. Triethylamine (3.0 g, 0.03 mol)was added and the
mixture heated to 80-108.degree. C. for 27 min. The mixture was
cooled to room temperature, filtered, and washed with acetone. The
product was slurried in acetone, filtered,and dried to yield 5.75 g
(90%) of gold-green crystals, mp282.degree. C., max(methanol)=810
(e=242,000).
[0138] The reactants were prepared as follows: Compound B was made
as above and 1,1,2,3-tetramethyl-1H-benz(e)indolium tosylate was
prepared as below:
[0139] 1,1,2-Trimethyl-1H-benz(e)indole (10.45 g, 0.05 mol), methyl
tosylate (9.3 g, 0.05 mol), and 40 mL o-xylene were heated to
150.degree. C. for 6 hrs. After cooling to 80.degree. C., the
mixture began to set up and acetone was quickly added. After
cooling to room temperature, the mixture was filtered and washed
with acetone. The product was slurried twice in acetone, filtered,
and dried to yield 16.56 g of white powder, mp 212.degree. C.
Example 5
2-[2-[2-(3,5-dimethyl-2,4,6-trioxo-1,3-pyrimidin-5-yl)-3-[2-(1,3-dimethyl--
4,5-quinoxalino-imidazol-2-ylidene)-ethylidene]-1-cyclopenten-1-yl]-etheny-
l]-1,3-dimethyl-4,5-quinoxalino-imidazolium, inner salt
(DF-13140)
[0140] The title compound was prepared as follows:
1,2,3-trimethyl-4,5-qui- noxalino-imidazolium 4-toluenesulfonate
(3.00 g, 0.0078 mol)and Compound B (1.66 g, 0.0039 mol) were mixed
with 20 mL dimethylformamide. Triethylamine (0.79 g) was added and
the mixture heated to 100.degree. C. for 100 min. The mixture was
cooled to room temperature and filtered. The product was slurried
in acetone for one hour, filtered, and air-dried to to yield 2.02
g, mp 283-289.degree. C., Amax(1% Acetic acid/methanol)=850
(e=213,000).
[0141] The reactants were prepared as follows: Compound B was made
as above and 1,2,3-trimethyl-4,5-quinoxalino-imidazolium
4-toluenesulfonate was made as follows:
[0142] 2,3-Bis-(3-methylamino)quinoxalinium 4-toluenesulfonate
(4.04 g), prepared by reaction of methyllamine with
2,3-dichloroquinoxaline, was refluxed with 420 mL acetic anhydride
for two hours. After cooling to room temperature, the reaction
mixture was poured into 3400 mL of stirred ethyl acetate. The
resulting precipitate was filtered out and reslurried in acetone.
Filtering and drying yielded 3.00 g, mp 253-258.degree. C.
(dec).
Example 6
2-[2-[2-[2,4,6-trioxo-1,3-pyrimidin-5-yl]-3-[1-ethyl-naphtho [1
2-d]thiazol-2(1
H)-ylidene)-ethylidene]-1-cyclopenten-1-yl]-ethenyl]-1-et-
hyl-2II-naphtho[1,2-d]thiazolium, inner salt (DF-1668)
[0143] The title compound was prepared as follows:
1-ethyl-2-methylnaphtho- [1,2-d]thiazolium tosylate (2.00 g, 0.005
mol) and Compound B (0.86 g, 0.0025 mol) were mixed with 35 mL
dimethylformamide. Triethylamine (0.76 g, 0.0075 mol) was added and
the mixture stirred at room temperature for 3.75 hrs. The mixture
was filtered and the product reslurried in ethyl acetate. The
product was collected by filtration and dried to yield 1.20 g, mp
246-249.degree. C., Amax(methanol)=848 (e=231,000).
[0144] The reactants were prepared as follows: Compound B was made
as above and 1-ethyl-2-methylnaphtho[1,2-d]thiazolium tosylate was
prepared as follows:
[0145] 2-Methylnaphtho[1,2-d]thiazole (19.9 g, 0.1 mol) and ethyl
tosylate (20 g, 0.1 mol) were heated together to 170-180.degree. C.
for 7 hrs. When the mixture was cooled to <60.degree. C.,
acetone was added. After cooling to room temperature, the mixture
set-up, was filtered, and the crude product slurried three times in
acetone to yield, after filtering and drying, 20 g of product
contaminated with starting material. The material was boiled with
acetone for 30 min., filtered hot, and vacuum-dried to yield 11.36
g, mp 127-139.degree. C.
Example 7
2-[2-[2-[2,4,6-trioxo-1,3-pyrimidin-5-yl]-3-[3-ethyl-6-methoxy-2(3H)benzot-
hiazolylidene)-ethylidene]-1-cyclopenten-1-yl]-ethenyl]-3-ethyl-6-methoxy--
2(3H)-benzothiazolium, inner salt (DF-15118)
[0146] The title compound was prepared as follows:
3-ethyl-6-methoxy-2-met- hylbenzothiazolium iodide (H.W. Sands,
1-1032, 1.50 g, 0.00446 mol) and Compound B (0.82 g, 0.00223 mol)
were mixed with 20 mL dimethylformamide. Triethylamine (0.67 g,
0.00669 mol) was added and the mixture stirred at room temperature
for 55 min. The mixture was filtered and the product reslurried in
ethyl acetate. The product was collected by filtration and dried to
yield 1.19 g, mp 238.degree. C., Amax(methanol)=826
(e=259,000).
Example 8
2-[2-[2-[2,4,6-trioxo-1,3-pyrimidin-5-yl]-3-[3-ethyl-2(3H)benzothiazolylid-
ene)-ethylidene]-1-cyclopenten-1-yl]-ethenyl]-3-ethyl-2(3H)-benzothiazoliu-
m inner salt (DF-15131)
[0147] 3-Ethyl-2-methylbenzothiazolium iodide (H. W. Sands,
I-1003,2.00 g, 0.00656 mol) and Compound B (1.40 g, 0.00328 mol)
were mixed with 60 mL dimethylformamide. Triethylamine (0.99 g,
0.00984 mol) was added and the mixture stirred at room temperature
for 2 hrs. The mixture was filtered and the product reslurried in
ethyl acetate. The product was collected by filtration and dried to
yield 1.71 g, mp 256.degree. C., Amax(methanol)=811
(e=259,000).
Example 9
2-[2-[2-[2,4,6-trioxo-1,3-pyrimidin-5-yl]-3-[3-(sulfopropyl)-5-trifluoro-m-
ethyl-2(3H)benzothiazolylidene)-ethylidene]-1-cyclopenten-1-yl]-ethenyl]-3-
-(3-sulfopropyl)-5-trifluoromethyl-2(3H)-benzothiazolium
bis-triethylammonium salt (DF-15132)
[0148] 2-Methyl-3-(3-sulfopropyl)-5-trifluoromethylbenzothiazolium,
inner salt (H. W. Sands, I-1069, 2.03 g, 0.006 mol) and Compound B
(1.28 g, 0.003 mol) were mixed with 80 mL dimethylformamide.
Triethylamine (0.91 g, 0.009 mol) was added and the mixture stirred
at room temperature for 9 hrs. The mixture was filtered and the
filtrate poured into 400 mL of stirring ethyl acetate. After
stirring 30 min., the product was collected by filtration and
reslurried again in ethyl acetate. After filtration and drying,
2.42 g copper-colored powder was obtained, mp 218-230.degree. C.,
Amax(methanol)=809 (e=280,000).
Example 10
2-[2-[2-Chloro-3-[3-ethyl-6-methoxy-2(3H)benzo-thiazolylidene)-ethylidene]-
-1-cyclopenten-1-yl
]ethenyl]-3-ethyl-6-methoxy-2(3H)-benzothiazolium iodide
(DF-15101)
[0149] The title compound was prepared as follows:
3-ethyl-6-methoxy-2-met- hylbenzothiazolium iodide (H. W. Sands,
I-1032, 1.18 g, 0.005 mol),
2-chloro-3-(anilinomethylene)-1-(aniliniummethyl)-cyclopent-1-ene
hydrochloride (0.86 g, 0.025 mol), and 20 mL dimethylformamide were
mixed together. Acetic anhydride (1.2 mL) was added, followed by
0.76 g (0.0165 mol) triethylamine. The mixture was stirred and
heated to 80-90.degree. C. for 30 min. The mixture was chilled with
a methanol-ice bath, then filtered. The filtrate was poured into
200 mL chilled ethyl acetate, stirred for one hour, and filtered.
The product was reslurried in ethyl acetate, filtered, and
air-dried to yield 0.55 g, mp 223-226.degree. C., max(methanol)=807
(e=96,000). The reactants were prepared as follows:
2-chloro-3-(anilinomethylene)-1-(aniliniummethyl)-cyclopent-1-ene
hydrochloride
[0150] The above reactant was prepared according to the procedures
in U.S. Pat. No. 4,882,265 and E.P. 0 420 012 A1.
[0151] The other sensitizers within the scope of the invention as
generically shown in Table 1 may readily be prepared according to
the processes shown above or in the preceding examples or via
analogous processes wherein 2 equivalents of the D moieties are
coupled to 1 equivalent of the cyclopentyllidene-A moiety.
Examples 11-18
[0152] In these examples, each member of a set of near IR dyes was
shown to be capable of inducing polymerization of a photopolymer
washoff film composition upon imaging using a 820 nm diode laser
operated at approximately 100 mW/cm2 intensity.
[0153] Each individual dye was tested as the photosensitizer
component in a photopolymer washoff composition which consisted of
the individual dye (0.25 g), TMPEOTA/TMPTA monomers (26.0 g/9.0 g),
N-phenylglycine (0.50 g), an acrylic binder polymer (MMA/EA/MAA
44/35/21 wt. %; 0.50 g), and a HABI photoinitiator (2.0 g). Two
separate sets of film samples were prepared and tested. In film set
#1, the HABI photoinitiator was o-Cl-HABI, and in film set #2, the
HABI photoinitiator was 2,3,5-TCl-HABI. The specific compositions
tested are listed below. Example 12 contained DF-1413; 13/DF-1419;
14/DF-1668; 15/DF-15118; 16/DF-15131; 17/DF-15132; 18/GW-826;
19/NK-2268.
[0154] Each photopolymer film composition (12-19) was
solvent-coated (from MEK, MEK/MeOH, or MeOH (5%)/CH.sub.2Cl.sub.2
at 33-35% total solids levels) to give a photopolymer dry film upon
solvent removal (drying) that was 1-2 mils thick. For testing of
each film sample, the following procedure was used. The
photopolymer film was laminated onto a copper substrate, imaged
using the 820 nm diode laser operated at a fluence of about 100
mW/cm2, and then processed (developed) on copper using a
Chemcut.RTM. 547 aqueous processor operated at 85.degree. F. with a
developer solution of 1% aqueous sodium carbonate solution.
[0155] Each of the above photopolymer film samples afforded a
well-defined imaged photopolymer (resist) pattern on the copper
that corresponds to the negative of the phototool. More
specifically, the unexposed (unimaged, unpolymerized) portions of
resist were essentially completely removed in development, while
the exposed (imaged, photopolymerized) portions were essentially
completely intact on the copper substrate, which afforded the
well-defined imaged resist pattern.
[0156] These examples demonstrate the photosensitizers of the
invention are effective as near IR sensitizers of a HABI
photoinitiator in initiating the polymerization of monomer(s)
present in the photopolymer composition upon exposure to actinic
radiation in the near IR range of the electromagnetic spectrum to
afford photopolymerized photopolymer. These near IR sensitizers
were effective in sensitizing both o-Cl-HABI (in film set #1) and
2,3,5-TCl-HABI (in film set #2).
Examples 19-24
[0157] In these examples, each member of a set of near IR dyes
listed below was shown to be capable of inducing polymerization of
a photopolymer washoff film composition upon imaging using a 790 nm
diode laser operated at approximately 100 mW/cm2 intensity (power
density).
[0158] Each individual dye was tested as the photosensitizer
component in a photopolymer washoff composition which consisted of
the individual dye (0.25 g), TMPEOTA/TMPTA monomers (26.0 g/9.0 g),
N-phenylglycine (0.50 g), an acrylic binder polymer (MMA/EA/MAA
44/35/21 wt. %; 0.50 g), and 2,3,5-TCl-HABI photoinitiator. The
specific compositions tested are listed below. Example 19 contained
GW-826; 20/NK-3877; 21/KF-634; 22/KF-677; 23/KF-679; and
24/KF-681.
[0159] Each photopolymer film composition (19-24) was
solvent-coated (from MEK, MEK/MeOH, or MeOH (5%)/CH.sub.2Cl.sub.2
at 33-35% total solids levels) to give a photopolymer dry film upon
solvent removal (drying) that was 1-2 mils thick. For testing of
each film sample, the following procedure was used. The
photopolymer film was laminated onto a copper substrate, imaged
using the 790 nm diode laser operated at a fluence of about 100
mW/cm2, and then processed (developed) on copper using a
Chemcut.RTM. 547 aqueous processor operated at 85.degree. F. with a
developer solution of 1% aqueous sodium carbonate solution. The
photopolymer film was laminated using a Riston.RTM. HRL-24
laminator operated at 1.5 meters/minute and at a temperature of
104.degree. C.
[0160] Each of the above photopolymer film samples afforded a
well-defined imaged photopolymer (resist) pattern on the copper
that corresponds to the negative of the phototool. More
specifically, the unexposed (unimaged, unpolymerized) portions of
resist were essentially completely removed in development, while
the exposed (imaged, photopolymerized) portions were essentially
completely intact on the copper substrate, which afforded the
well-defined imaged resist pattern.
[0161] These examples further demonstrate the photosensitizers
within the scope of the invention are effective as near IR
sensitizers of a HABI photoinitiator in initiating the
polymerization of monomer(s) present in the photopolymer
composition upon exposure to actinic radiation in the near IR range
of the electromagnetic spectrum to afford photopolymerized
photopolymer.
Example 25
[0162] In this example, dye DF-12124 was tested in the manner as
outlined above for Examples 19-24 except that the 790 diode laser
was operated at a power density of 511 mW/cm2; HABI photoinitiator
was o-Cl-HABI at a level of 2.0 g in the photopolymerizable
composition; and the chain transfer agent was
triphenylbutylborate.
[0163] This photopolymer film sample afforded a well-defined imaged
photopolymer (resist) pattern on the copper that corresponds to the
negative of the phototool. More specifically, the unexposed
(unimaged, unpolymerized) portions of resist were essentially
completely removed in development, while the exposed (imaged,
photopolymerized) portions were essentially completely intact on
the copper substrate, which afforded the well-defined imaged resist
pattern.
[0164] This example demonstrates that this particular near IR
photosensitizer within the scope of the invention is effective as
near IR sensitizer of a HABI photoinitiator in initiating the
polymerization of monomer(s) present in the photopolymer
composition upon exposure to actinic radiation in the near IR range
of the electromagnetic spectrum to afford photopolymerized
photopolymer.
Example 26
[0165] This example illustrates the effect of not including a near
IR dye in the photopolymerizable composition. In this example, the
testing was in the manner as outlined above for Example 25, using a
790 nm diode laser operated at a power density of 511 mW/cm2,
except that no near IR dye was present and no chain transfer agent
was present. No image was obtained upon development, indicating
that a HABI photoinitiator alone in a photopolymerizable
composition is insufficent to afford photopolymerization upon
exposure to near IR actinic radiation. A suitable near IR
photosensitizer within the scope of the invention is also needed in
addition to a HABI photoinitator to afford photopolymerization
using near IR actinic radiation.
Examples 27-29
[0166] These examples illustrate that the near IR dyes of this
invention are very effective as photosensitizers of HABI
photoinitiators even at very low power density levels of the
actinic radiation source. In these examples, each member of a set
of near IR dyes listed below was shown to be capable of inducing
polymerization of a photopolymer washoff film composition upon
imaging using a spectral sensitometer operated at approximately 2-5
mW/cm2 intensity (power density) and at a output wavelength
(lambda(max)) that was adjustable and set at or very close to the
wavelength of maximum absorption of the dye compound being
tested.
[0167] Each individual dye was tested as the photosensitizer
component in a photopolymer washoff composition which consisted of
the individual dye (0.25 g), TMPEOTA/TMPTA monomers (26.0 g/9.0 g),
N-phenylglycine (0.50 g), an acrylic binder polymer (MMA/EA/MAA
44/35/21 wt. %; 0.50 g), and either o-Cl-HABI or 2,3,5-TCl-HABI
photoinitiator. The specific compositions tested and
wavelength/power density settings for the spectral sensitometer are
listed below. Example 27 contained GW-826/o-Cl-HABI/NPG with
settings of 711 nm/5 mW/cm2; 28/DF-1413/o-Cl-HABI/NPG with settings
of 780 nm/3 mW/cm2; and 29/DF-1413/2,3,5-TCl-HABI/Julolidine with
settings of 780 nm/3 mW/cm2.
[0168] Each photopolymer film composition (19-24) was
solvent-coated (from MEK, MEK/MeOH, or MeOH (5%)/CH.sub.2Cl.sub.2
at 33-35% total solids levels) to give a photopolymer dry film upon
solvent removal (drying) that was 1-2 mils thick. For testing of
each film sample, the following procedure was used. The
photopolymer film was laminated onto a copper substrate, imaged
using the spectral sensitizer operated at the wavelength and the
fluence as indicated above, and then processed (developed) on
copper using a Chemcut.RTM. 547 aqueous processor operated at
85.degree. F. with a developer solution of 1% aqueous sodium
carbonate solution. The photopolymer film was laminated using a
Riston.RTM. HRL-24 laminator operated at 1.5 meters/minute and at a
temperature of 104.degree. C.
[0169] Each of the above photopolymer film samples afforded a
well-defined imaged photopolymer (resist) pattern on the copper
that corresponds to the negative of the phototool. More
specifically, the unexposed (unimaged, unpolymerized) portions of
resist were essentially completely removed in development, while
the exposed (imaged, photopolymerized) portions were essentially
completely intact on the copper substrate, which afforded the
well-defined imaged resist pattern.
[0170] These examples further demonstrate the photosensitizers
within the scope of the invention are effective as near IR
sensitizers of a HABI photoinitiator in initiating the
polymerization of monomer(s) present in the photopolymer
composition upon exposure to actinic radiation in the near IR range
of the electromagnetic spectrum to afford photopolymerized
photopolymer. Furthermore, the fact that these photosensitizers
that are within the scope of the invention are very effective even
at very low power density levels (.about.3-5 mW/cm2) strongly
indicates that these photosensitizers operate predominantly by a
photochemical mechanism (more efficient) as opposed to predominatly
by a photothermal mechanism (much less efficient).
Example 30
[0171] In this example, a near IR dye within the scope of this
invention is shown to be effective as a sensitizer of a HABI
photoinitiator for photoimaging with a leuco dye, which is oxidized
to the colored dye form to create the image.
[0172] A coating solution is prepared by mixing the following
ingredients in the amounts indicated: acetone (65 g),
diisopropylamine (1 g), p-formylphenoxyacetic acid (0.8 g),
o-formylphenoxyacetic acid (0.8 g),
nonylphenoxypoly(etheneoxy)ethanol (1.0 g), tricresyl phosphate
(1.0 g), Leuco crystal violet (LCV, 0.4 g), DF-1413 dye (0.6 g),
ethylenediamine tetraacetic acid (1.0 g), cellulose acetate
butyrate (.about.27% butyryl content hydroxyl/2 anhydroglucose
units, 6.0 g), 1-phenylpyrazolidine-3-o- ne (0.048 g), and
2,3,5-TCl-HABI (0.32 g).
[0173] The solution is coated on Schweitzer 32-HG paper with a 0015
coating bar and then dried. Exposure through a phototool with a 820
nm diode laser operating at approximately a power density of 100
mW/cm2 affords a well-defined colored image as defined by the
phototool.
Example 31
[0174] A coating solution is prepared by mixing the following
ingredients in the amounts indicated: acetone (65 g), Leuco crystal
violet (0.4 g), DF-1413 dye (0.6 g), 2,3,5-TC.sub.1HABI (0.3 g),
cellulose acetate butyrate (.about.27% butyryl content hydroxyl/2
anhydroglucose units, 8.0 g), triethanolamine triacetate (0.25 g),
and 9,10-phenanthrenequinone (0.5 g).
[0175] The solution is coated on Schweitzer 32-HG paper with a 0015
coating bar and then dried. Exposure through a phototool with a 820
nm diode laser operating at approximately a power density of 100
mW/cm2 affords a well-defined colored image as defined by the
phototool.
Example 32
[0176] The following example shows the use of a near
infrared-sensitive photosensitizer of the present invention in a
printing element that is photoimaged using a near IR light
source.
[0177] A photosensitive element for use as a flexographic printing
element includes a support, a coversheet and a photohardenable
layer between the support and coversheet.
[0178] The support is a polyethylene terephthalate film. The
support can be treated to improve adhesion by, for example, flame
treatment or corona treatment.
[0179] The coversheet is a polyethylene terephthalate film coated
with a release layer, for example, a thin polymeric layer of
polyamide.
[0180] The photohardenable layer is prepared having the following
composition, wherein the all parts are by weight:
5 Function Component Parts Binder Styrene-butadiene-styrene block
61.30 copolymer Binder Styrene-butadiene block copolymer 9.90
Polyoil plasticizer 1,4-Polybutadiene, MW 300 18.80 Monomer
Hexamethylenediol diacrylate 6.90 Solvent Hydroxethyl methacrylate
0.2 Antioxidant Butyrated hydroxy toluene 0.28 Stabilizer
1,4,4-Trimethyl-2,3-diazobicyclo 0.02 (3.2.2)-non-2-ene-2,3-dioxi-
de Photoinitiator o-Cl-HABI 2.00 Chain Transfer 2MBO 0.30
Photosensitizer GW-826 (near Infrared) Dye 0.3 TOTAL 100%
[0181] The components for the photohardenable composition are
solvent coated from a suitable solvent such as a toluene/acetone
blend (e.g., 90/10) using a slot die coater operated at ambient
temperature onto a PET support. A coversheet is applied on top of
the photohardenable composition so that the photohardenable layer
is sandwiched between the support and the coversheet. This 3-layer
structure is the photosensitive element. It is wound onto a roll
for storage until being used for making a flexographic printing
plate.
[0182] The photosensitive element, as a printing element, is then
processed to produce a flexographic printing plate. The
photosensitive element is first given either a blanket ultraviolet
light (UV) exposure through the support or a blanket near infrared
exposure with the support removed in order to sensitize the plate
and to polymerize the back side in order to establish the depth of
the plate relief by creating a "floor". After the coversheet is
removed (in case of a blanket UV exposure), the element is given an
imagewise exposure through a phototool using near infrared
radiation at a level of 100 mW/cm.sup.2 for about 4 seconds (time
units). The exposed element is washed in a processor using a
suitable developer solvent, for example, tetrachloroethylene (TCE),
or a mixture of a solvent, such as TCE, with suitable alcohols. The
washed element will have a relief image for use as a flexographic
printing plate. The plate is dried in an oven at 60.degree. C. for
about two hours. The plate is then uniformly post-exposed using the
same source of near infrared radiation as the main exposure to
insure complete polymerization. Optionally, if the plate surface is
tacky, the plate may be detackified by treatment with bromine or
chlorine solution, or exposure to radiation sources having a
wavelength not longer than 300 nm. At this stage, the processed
plate is now ready for use as a flexographic printing plate for
printing.
Comparative Examples
[0183] In this comparative example, a photopolymer film was made
and tested in the manner as given in Examples 27-29, except that
SQS, a near IR dye photosensitizer that is very effective for
thermal imaging (see U.S. Pat. No. 5,019,549), was used in
equimolar levels in place of the near IR dyes tested in Examples
27-29. All other procedures were the same as previously described.
Upon exposure and during the course of development, all of the
photopolymer film was washed off the copper surface leaving a
nearly bare or bare copper substrate with no image. This experiment
indicates that the combination of SQS and a HABI photoinitiator is
not capable of efficiently initiating the polymerization of
monomer(s) in a photopolymer film upon exposure to near IR actinic
radiation, such that both exposed and unexposed areas remain
unpolymerized and are thus washed off in the course of development
to afford a bare copper substrate. When used at significantly
higher levels (e.g., 2.5% or more by weight) SQS is seen to
initiate photopolymerization only at significantly higher
intensities or power densities (megawatts/cm). As discussed
elsewhere in the body of the specification, it is believed that the
near IR photosensitizers of this invention work via a photochemical
mechanism of energy transfer while SQS works less efficiently and
only when present in higher levels via a photothermal mechanism of
energy transfer.
6TABLE 1 3
[0184] Where A= 4
[0185] D1= 5
[0186] D2= 6
[0187] Z=NR.sup.8,C,O, or S
[0188] U=NR.sup.3,S,P, or O
[0189] Y=
[0190] or U 7
[0191] R.sup.1-R.sup.2=H,C.sub.1-C.sub.6 alkyl, Ar, which is
"phenyl or napthyl which is unsubstituted or substituted with
halogen atom, O(C.sub.1-C.sub.6 alkyl), (C.sub.6-C.sub.10) aryl, or
CF.sub.3, (C.sub.1-C.sub.6) alkyl (C.sub.6-C.sub.10) aryl";
[0192] R.sup.3=C.sub.1-C.sub.6 alkyl unsubstituted or substituted
with CO.sub.2H, SO.sub.3H or salts thereof;
[0193] R.sup.4-R.sup.7=H, halogen, OCH.sub.3,CF.sub.3 or any two of
R.sup.4-R.sup.7 which are ortho to each other may form a phenyl
ring which may be unsubstituted or substituted;
[0194] R.sup.8=H, C.sub.1-C.sub.6 alkyl, CO.sub.2H,
CO.sub.2-(C.sub.1-C.sub.6 alkyl), (CH.sub.2)m CO.sub.2H,
(CH.sub.2)m CO.sub.2 (C.sub.1-C.sub.6 alkyl); and
[0195] n=1-2
[0196] m
[0197] 0-6
[0198] het=a C.sub.6-C.sub.10 heteroatomic ring or fused ring
having at least one heteratom selected from the group consisting of
oxygen, nitrogen, and sulfur.
7TABLE 2 8 Ex. No./ Substituent Substituent Substituent Dye A
D.sub.1 D.sub.2 n DF-15131 9 10 11 1 DF-15118 12 13 14 1 DF-1668 15
16 17 1 DF-15132 18 19 20 1 DF-1422 21 22 23 DF-1429 24 25 26
DF-1413 27 28 29 1 DF-1419 30 31 32 1 NK-2268 33 34 35 1 NK-3877 36
37 38 1 GW-826 39 40 41 1 DE-12124 42 43 44 1 GW-976 45 46 47 2
GW-436 48 49 50 2 GW-186 51 52 53 2 GW-776 54 55 56 2
* * * * *