Iodonium salts as latent acid donors

Details Iodonium salts as latent acid donors Iodonium salts as latent acid donors

2000-12-18

2001-10-23

Ashton, Rosemary (Department: 1752)

Radiation imagery chemistry: process, composition, or product th

Imaging affecting physical property of radiation sensitive...

Radiation sensitive composition or product or process of making

C430S914000, C522S031000, C556S064000, C568S001000, C568S006000, C568S016000, C568S028000

Reexamination Certificate

active

06306555

ABSTRACT:

The invention relates to selected iodonium salt compounds and to their use as photoinitiators.
It is known to use iodonium salts as photoinitiators in cationically polymerisable compositions. Such disclosures can be found, for example, in J. V. Crivello, “Photoinitiated Cationic Polymerization” in: UV Curing: Science and Technology, Editor S. P. Pappas, pages 24-77, Technology Marketing Corporation, Norwalk, Conn. 1980, ISBN No. 0-686-23773-0; J. V. Crivello, J. H. W. Lam, Macromolecules, 10, 1307 (1977) and J. V. Crivello, Ann. Rev. Mater. Sci. 1983, 13, pages 173-190 and J. V. Crivello, Journal of Polymer Science, Part A: Polymer Chemistry, Vol. 37, 4241-4254 (1999). WO 98/46647 discloses 4,4′-dialkylphenyliodonium compounds containing at least one isopropyl group in photocurable compositions. J. Chem. Soc. Perkin Trans. 1, 1997,17, pages 2463-2465 discloses a special process for the manufacture of asymmetrically substituted diaryliodonium triflates and trifluoroacetates, which can be used to prepare 4-tert-butylphenyl-2′-methylphenyl-iodonium triflate and trifluoroacetate, respectively.
The hitherto known iodonium-salt-containing radiation-reactive compositions available for technical uses have a number of disadvantages that are attributable to the iodonium salts used. For example, diphenyliodonium salts have poor solubility in the formulations, which limits their use in practice since only a low concentration of the iodonium salt can be used, otherwise there is a risk that it will crystallise out. Moreover, phenyliodonium salts release benzene as a photoproduct, which can migrate out of the cured compound or coating (e.g. printing ink) into the substrate or is released into the environment and is highly undesirable for toxicological reasons (e.g. in the printing of foodstuffs packaging). Whilst the substitution of one of the phenyl rings by longer-chained alkyl or alkoxy substituents can improve the solubility, the disadvantage of the formation of benzene remains. Large substituents generally not only reduce the reactivity, but also make it significantly more difficult to handle the compounds, which are then no longer obtained in crystalline form and can be prepared only with difficulty in the high purity that is required especially for use in the field of microelectronics. It has also been shown that phenylaryliodonium salts, from which benzene may be produced upon exposure, give a positive reaction in the AMES test, which is used for initial detection of mutagenic potential, that is to say they are suspected of having mutagenic activity.
It has now been found that radiation-sensitive compositions comprising
(a1) a cationically or acid-catalytically polymerisable or crosslinkable compound, or
(a2) a compound that increases its solubility in a developer under the action of acid; and
(b) at least one diaryliodonium salt of formula I
wherein
X is branched C
3
-C
20
alkyl or C
3
-C
8
cycloalkyl;
X
1
is hydrogen, linear C
1
-C
20
alkyl, branched C
3
-C
20
alkyl or C
3
-C
8
cycloalkyl; with the proviso that the sum of the carbon atoms in X and X
1
is at least 4;
Y is linear C
1
-C
10
alkyl, branched C
3
-C
10
alkyl or C
3
-C
8
cycloalkyl;
A
−
is a non-nucleophilic anion, selected from the group (BF
4
)
−
, (SbF
6
)
−
, (PF
6
)
−
, (B(C
6
F
5
))
4
−
, C
1
-C
20
alkylsulfonate, C
2
-C
20
haloalkylsulfonate, unsubstituted C
6
-C
10
arylsulfonate, camphorsulfonate, C
1
-C
20
-perfluoroalkylsulfonylmethide, C
1
-C
20
-perfluoroalkylsulfonylimide, and C
6
-C
10
arylsulfonate substituted by halogen, NO
2
, C
1
-C
12
alkyl, C
1
-C
12
halo-alkyl, C
1
-C
12
alkoxy or by COOR
1
; and
R
1
is C
1
-C
20
alkyl, phenyl, benzyl; or phenyl mono- or poly-substituted by C
1
-C
12
alkyl, C
1
-C
12
alkoxy or by halogen;
with the proviso that the two phenyl rings on the iodine atom are not identically substituted; have an optimum balance between high sensitivity, good storage stability, good solubility and a low tendency to crystallise.
Linear C
1
-C
20
alkyl is, for example, C
1
-C
12
-, C
1
-C
8
-, C
1
-C
6
- or C
1
-C
4
-alkyl. Examples thereof include methyl, ethyl, propyl, n-butyl, n-pentyl, n-hexyl, n-heptyl, n-octyl, n-nonyl, n-decyl, n-undecyl, n-dodecyl, n-tetradecyl, n-pentadecyl, n-hexadecyl, n-heptadecyl, n-octadecyl, n-nonadecyl and n-icosyl. For example, Y is C
1
-C
8
alkyl, especially C
1
-C
6
alkyl, preferably C
1
-C
4
alkyl, such as, for example, methyl or n-butyl. Special preference is given to methyl.
Branched C
3
-C
20
alkyl is, for example, C
3
-C
12
-, C
3
-C
8
-, C
3
-C
6
- or C
3
-C
4
-alkyl. Examples thereof include branched propyl, such as isopropyl, branched butyl, such as sec-butyl, isobutyl or tert-butyl, branched pentyl, such as 2-methylbutyl, 3-methylbutyl or 1-methylbutyl, branched hexyl, such as 1-methylpentyl, 2-methylpentyl or 4-methylpentyl, branched heptyl, such as 1-methylhexyl, 1-ethylpentyl, 4-ethylpentyl, 1-methylhexyl or 5-methylhexyl, branched octyl, such as 2,4,4-trimethylpentyl, 2-ethylhexyl or 1-methylheptyl, branched nonyl, branched decyl, branched undecyl, branched dodecyl, branched tetradecyl, branched pentadecyl, branched hexadecyl, branched heptadecyl, branched octadecyl, branched nonadecyl and branched icosyl. For example, Y is branched C
3
-C
8
alkyl, especially branched C
3
-C
6
alkyl, preferably branched C
3
-C
4
alkyl, such as, for example, isopropyl, sec-butyl, isobutyl or tert-butyl.
Branched C
4
-C
20
alkyl can have the above-mentioned meanings up to the corresponding number of carbon atoms. X is, for example, C
4
-C
12
- or C
4
-C
8
-alkyl, such as sec-butyl, isobutyl, tert-butyl or tert-amyl, especially isobutyl or tert-amyl.
C
1
-C
20
Alkyl is linear or branched and is, for example, C
1
-C
12
-, C
1
-C
8
-, C
1
-C
6
- or C
1
-C
4
-alkyl. Examples thereof include methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, pentyl, hexyl, heptyl, 2,4,4-trimethylpentyl, 2-ethylhexyl, octyl, nonyl, decyl, undecyl, dodecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, nonadecyl and icosyl. C
1
-C
12
Alkyl is likewise linear or branched and has the above-mentioned meanings up to the corresponding number of carbon atoms.
C
3
-C
8
Cycloalkyl is, for example, cyclopropyl, cyclopentyl, cyclohexyl or cyclooctyl, especially cyclopentyl or cyclohexyl, preferably cyclohexyl.
Halogen is fluorine, chlorine, bromine or iodine, especially chlorine or fluorine, preferably fluorine.
C
1
-C
20
Haloalkyl is a mono- or poly-halo-substituted C
1
-C
20
alkyl. The alkyl moiety can be substituted by a plurality of identical halogen atoms or, alternatively, by different halogen atoms. When C
1
-C
20
alkyl is mono- or poly-halo-substituted, there are, for example, from 1 to 3, or 1 or 2, halogen substituents present on the alkyl moiety.
C
1
-C
20
Alkylsulfonate is RSO
3
−
wherein R is linear or branched C
1
-C
20
alkyl as described above. Examples thereof include methylsulfonate, ethylsulfonate, propylsulfonate, pentylsulfonate and hexylsulfonate.
C
2
-C
20
Haloalkylsulfonate is RSO
3
−
wherein R is halo-substituted C
2
-C
20
alkyl, C
2
-C
10
-, C
2
-C
8
- or C
4
-C
8
-alkyl. Examples thereof include C
2
F
5
SO
3
−, C
4
F
9
SO
3
−
and C
8
F
17
SO
3
−
.
Unsubstituted C
6
-C
10
arylsulfonate is RSO
3
−
wherein R is C
6
-C
10
aryl, e.g. phenyl or naphthyl.
Alkyl-substituted arylsulfonates are, for example, toluenesulfonate, 2,4,6-trimethylbenzenesulfonate, 2,4,6-tris(isopropyl)benzenesulfonate, 4-tert-butylbenzenesulfonate and 4-dodecylbenzenesulfonate.
Halo-substituted arylsulfonates are, for example, 4-chlorobenzenesulfonate, 4-fluorobenzenesulfonate, 2,4,6-trifluorobenzenesulfonate and pentafluorobenzenesulfonate.
Camphorsulfonate is
C
1
-C
12
Alkoxy denotes linear or branched radicals and is, for example, C
1
-C
8
-, C
1
-C
6
- or C
1
-C
4
-alkoxy. Examples thereof include methoxy, ethoxy, propoxy, isopropoxy, n-butyloxy, sec-butyloxy, isobutyloxy, tert-butyloxy, pentyloxy, hexyloxy, heptyloxy, 2,4,4-trimethylpentyloxy, 2-ethylhexyloxy, octyloxy, nonyl

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