Bifunctional photoinitiators suitable for...

Details Bifunctional photoinitiators suitable for... Bifunctional photoinitiators suitable for...

2001-05-16

2002-12-10

Chang, Ceila (Department: 1626)

Organic compounds -- part of the class 532-570 series

Organic compounds

Four or more ring nitrogens in the bicyclo ring system

C544S107000, C544S161000, C568S029000, C568S031000

Reexamination Certificate

active

06492514

ABSTRACT:

FIELD OF INVENTION
The present invention concerns new compounds containing in the same molecule two functional groups, which can give rise to radicals by a photochemical process. The compounds are suitable as polymerisation photoinitiators in photopolymerisable formulations containing ethylenic unsaturated systems.
PRIOR ART
Known photoinitiators contain in the molecule a functional group, which can give rise to radicals by excitation by an electromagnetic radiation, generally an UV radiation. These compounds are reported, for instance, in U.S. Pat. No. 3,715,293, DE 2722264, EP 161463, EP 3002, EP 88050, EP 284561, EP 192967, EP 850253. They are commonly used in polymerisation of ethylenic unsaturated systems. When pigmented systems are involved, such as in printing inks, the irradiating light cannot fully penetrate into the layer due to reflection and absorption of the pigment in the formulation. To obtain a good polymerization degree both at the surface level and in the inner layers of an ink, i.e. the so called surface and through cure of an ink, it is common practice to prepare formulations containing both a photoinitiator with a maximum UV absorption in the region of 250 nm and a photoinitiator with a significant absorption in the region above 300 nm. In fact above 300 nm most pigments have minimum in absorption and reflection (optical window) allowing the penetration of the light. The combination of the two kind of photoinitiators allows both surface and through cure of the formulation.
SUMMARY OF THE INVENTION
We have now surprisingly discovered the subject of the present invention, namely that molecules containing in their structure two different active moieties, both suitable to give rise to radicals, display high activity as photoinitiators, in particular in pigmented systems. The molecules can develop surprising synergies in comparison with the combined use of two photoinitiators containing each only one of the corresponding photoactive groups.
Moreover the absence in the molecule of functional groups that release volatile, odorous products by photolysis, improves the safety in the working environment, limiting the presence of volatile substances during the photopolymerisation stages in industrial processes.
Molecules generally used for the above mentioned purposes are based on two phenyl groups linked together, each substituted by a photochemically active ketonic moiety. The aromatic groups can be further substituted by non-photochemically active moieties. Among these molecules those based on two phenyl rings connected together through a suitable linking group and substituted in positions 4,4′ by two ketonic moieties are the most suitable.
Therefore the present invention deals with compounds having formula (I)
wherein
X
1
and X
2
are different
X
1
is a group
wherein
R
1
and R
2
, each independently, are —H or C
1
-C
12
linear or branched or cyclic alkyl chain, aryl, alkylaryl groups.
Z
1
is —SO
2
R
3
, —NR
4
R
5
, —OR
1
, halogen.
R
3
is: C
1
-C
12
linear or branched alkyl chain, or:
wherein
R
6
, R
7
, R
8
, R
9
and R
10
each independently, are —H or C
1
-C
12
linear or branched or cyclic alkyl chain, aryl group,—OR
11
, -alcohoxyhydroxy, hydroxyalkylthio-, —SR
11
, —S═OR
12
, —SO
2
R
13
, —C═OR
14
, —NR
15
R
16
, CN, -halogen;,
R
11
is —H, C
1
-C
12
linear or branched alkyl chain, aryl group,
R
12
is C
1
-C
12
linear or branched alkyl chain, aryl group,
R
13
is C
1
-C
12
linear or branched alkyl chain, aryl group, —OH, —OAlkyl, —NH
2
, —NHAlkyl, —N(Alkyl)
2
, —NH Aryl, —N(Aryl)
2
,
R
14
is —H, C
1
-C
12
linear or branched alkyl chain, aryl group, —OH, —OAlkyl, —NH
2
, —NHAlkyl, —N(Alkyl)
2
, —NH Aryl, —N(Aryl)
2
,
R
15
and R
16
, each independently, are —H, C
1
-C
12
linear or branched alkyl chain, aryl group, COR
1
or, if coincident, represent C
2
-C
6
alkylene, C
2
-C
6
oxa-, thia- or aza-alkylene,
R
4
and R
5
, each independently, are —H, C
1
-C
12
linear or branched alkyl chain, aryl group, COR
1
or, if coincident, represent C
2
-C
6
alkylene, C
2
-C
6
oxa-, thia- or aza-alkylene,
X
2
is a group
wherein
R
6
, R
7
, R
8
, R
9
, R
10
have the meaning already stated or X
2
is a group
wherein
R
1
, R
2
have the meaning already stated, and Z
2
has the same meaning of Z
1
provided that X
2
is different from X
1
Y is: single bond, C
1
-C
12
linear or branched alkylene, —O—, —S—, >S═O, >SO
2
, —NR
17
—,
wherein
R
17
is —H, C
1
-C
12
linear or branched alkyl chain, aryl group, CO R
1
.
The present invention further relates to photopolymerisable formulations containing at least one of the components of formula (I).
DETAILED DESCRIPTION OF THE INVENTION
Preferred photonitiators for pigmented systems are compounds of formula (I) in which:
Y is: single bond, —S—, —NR
17
—, wherein R
17
is —H, C
1
-C
12
linear or branched alkyl chain, aryl group, CO R
1
.
Particularly preferred as photoinitiators for pigmented systems are compounds of formula (I) in which:
X
1
is a group
wherein
R
1
and R
2
, each independently , are —H or C
1
-C
12
linear or branched or cyclic alkyl chain, aryl, alkylaryl groups.
Z
1
is —SO
2
R
3
, —NR
4
R
5
, halogen
R
3
is: C
1
-C
12
linear or branched alkyl chain, or:
wherein
R
6
, R
7
, R
8
, R
9
and R
10
each independently, are —H or C
1
-C
12
linear or branched or cyclic alkyl chain;
R
4
and R
5
are each independently, H, C
1
-C
12
linear or branched alkyl, aryl, COR
1
or, if coincident, represent C
2
-C
6
alkylene, C
2
-C
6
oxa-, thia- or aza-alkylene,
X
2
is a group
wherein
R
6
, R
7
, R
8
, R
9
and R
10
each independently, are —H or C
1
-C
12
linear or branched or cyclic alkyl chain, aryl group,—OR
11
, -alcohoxyhydroxy, hydroxyalkylthio-, —SR
11
, —S═OR
12
, —SO
2
R
13
, —C═OR
14
, —NR
15
R
16
, CN, -halogen;
R
11
is —H, C
1
-C
12
linear or branched alkyl chain, aryl group,
R
12
is C
1
-C
12
linear or branched alkyl chain, aryl group,
R
13
is C
1
-C
12
linear or branched alkyl chain, aryl group, —OH, —OAlkyl, —NH
2
, —NHAlkyl, —N(Alkyl)
2
, —NH Aryl, —N(Aryl)
2
,
R
14
is —H, C
1
-C
12
linear or branched alkyl chain, aryl group, —OH, —OAlkyl, —NH
2
, —NHAlkyl, —N(Alkyl)
2
, —NH Aryl, —N(Aryl)
2
,
R
15
and R
16
, each independently, are —H, C
1
-C
12
linear or branched alkyl chain, aryl group, COR
1
or, if coincident, represent C
2
-C
6
alkylene, C
2
-C
6
oxa-, thia- or aza-alkylene,
or a group
wherein
R
1
and R
2
, are defined above.
Z
2
is —SO
2
R
3
, —NR
4
R
5
, —OR
1
, halogen wherein R
1
, R
3
, R
4
and R
5
, are defined above
Y is: —S—, —NR
7
—, wherein R
17
is —H, C
1
-C
12
linear or branched alkyl chain, aryl group, CO R
1
.
Examples of compounds suitable for the application according to the present invention are the following, however the present invention is by no means limited thereto:
4-benzoyl-4′-(2-bromo-2-methyl-1-propanoyl)diphenylsulfide (1)
4-(4-methylbenzoyl)-4′-(2-bromo-2-methyl-1-propanoyl)diphenylsulfide (2)
4-(4-phenylbenzoyl)-4′-(2-bromo-2-methyl-1-propanoyl)diphenylsulfide (3)
4-(4-fluorobenzoyl)-4′-(2-bromo-2-methyl-1-propanoyl)diphenylsulfide (4)
4-(2-methylbenzoyl)-4′-(2-bromo-2-methyl-1-propanoyl)diphenylsulfide (5)
4-benzoyl-4′-(2-bromo-1-propanoyl)diphenylsulfide (6)
4-(2,4,6-trimethylbenzoyl)-4′-(2-bromo-2-methyl-1-propanoyl)diphenylsulfide (7)
4-(2-hydroxybenzoyl)-4′-(2-bromo-2-methyl-1-propanoyl)diphenylsulfide (8)
4-(4-methoxybenzoyl)-4′-(2-bromo-2-methyl-1-propanoyl)diphenylsulfide (9)
4-(4-cianobenzoyl)-4′-(2-bromo-2-methyl-1-propanoyl)diphenylsulfide (10)
4-benzoyl-4′-(2-bromo-2-phenyl-1-ethanoyl)diphenylsulfide (11)
4-benzoyl-4′-[2-(4-methylphenylsulfonyl)-2-methyl-1-propanoyl]diphenylsulfide (12)
4-(4-methylbenzoyl)-4′-[2-(4-methylphenylsulfonyl)-2-methyl-1-propanoyl]diphenylsulfide (13)
4-benzoyl-4′-phenylacetyl-diphenylsulfide (14)
4-benzoyl-4′-[2-(4-methylphenylsulfonyl)-2-phenyl-1-ethanoyl]diphenylsulfide (15)
4-(4-phenylbenzoyl)-4′-[2-(4-methylphenyl

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