Organic compounds -- part of the class 532-570 series – Organic compounds – Carboxylic acid esters
Reexamination Certificate
2002-07-19
2004-08-31
Lipman, Bernard (Department: 1713)
Organic compounds -- part of the class 532-570 series
Organic compounds
Carboxylic acid esters
C560S219000, C560S220000, C560S221000
Reexamination Certificate
active
06784312
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to (a) novel fluorine-containing monomers having a special structure, that is, a hydroxyl group or a substituent for protecting or modifying hydroxyl group, (b) polymers prepared by polymerization or copolymerization of such monomers, and (c) materials (e.g., reflection preventive materials, photosensitive coatings, and resist materials) containing such polymers.
Fluorine-containing compounds have been used and developed in various fields particularly in the field of advanced materials due to their good qualities (e.g., water repellency, oil repellency, low water absorption, heat resistance, weather resistance, corrosion resistance, transparency, photosensitivity, low refractive index, and low dielectric property). In particular, there have been active researches and developments of fluorine-containing compounds in the fields of (a) reflection preventive films utilizing low refractive index and visible light transparency of fluorine-containing compounds, (b) optical devices utilizing transparency of fluorine-containing compounds in a long wavelength band for optical communication, and (c) resist materials utilizing transparency of fluorine-containing compounds in ultraviolet region (particularly vacuum ultraviolet wavelength region). In these fields, the common task of designing polymers is to achieve adhesion to the substrate and high glass transition point (hardness), while achieving transparency at each wavelength for use by introducing as many fluorine atoms as possible into the polymer. Although there have been various proposals for increasing transparency at each wavelength by increasing the fluorine content in the polymer, there is no or very few proposals for improving water repellency and adhesion and for obtaining higher glass transition point by newly designing fluorine-containing monomers themselves. Recently, there have been some reports of hydroxyl group-containing and fluorine-containing styrenes and hydroxyl group-containing and fluorine-containing norbornene compounds in the field of the next generation F
2
resist in vacuum ultraviolet region. However, there are demands for new materials (i.e., novel polymers and novel monomers for providing novel polymers) having a sufficiently low refractive index necessary for reflection preventive films, for those having a sufficient transparency at optical communication wavelength, and for those having both of a sufficient transparency in ultraviolet region and a sufficient etching resistance.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a novel polymerizable monomer capable of providing polymers that have (a) high transparency in a wide wavelength region from vacuum ultraviolet region to optical communication wavelength region, (b) improved adhesion to the substrate, and (c) improved film forming property.
According to the present invention, there is provided a polymerizable monomer represented by the general formula (
1
),
wherein R
1
is a hydrogen atom, a halogen atom, a hydrocarbon group or a fluorine-containing alkyl group;
R
2
is a straight-chain or branched alkyl group, a cyclic alkyl group, an aromatic group, or a substituent having at least two of these groups, said R
2
being optionally partially fluorinated;
R
3
is a hydrogen atom, a hydrocarbon group that is optionally branched, a fluorine-containing alkyl group, or a cyclic group having an aromatic or alicyclic structure, said R
3
optionally containing a bond of an oxygen atom or carbonyl group; and
n is an integer of 1-2.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The above-mentioned novel polymerizable monomer according to the present invention is a fluorine-containing acrylate derivative having a high fluorine content and a hydroxyl group or a substituent (R
3
) for protecting or modifying the hydroxyl group. The inventors unexpectedly found that polymers prepared by polymerization or copolymerization using the novel polymerizable monomer have (a) high transparency in a wide wavelength region from vacuum ultraviolet region to optical communication wavelength region, (b) improved adhesion to the substrate, and (c) improved film forming property. Therefore, the resulting polymers are very useful for reflection preventive materials, optical device materials and resist materials. Furthermore, the polymerizable monomer, which is an acrylic monomer, is easy to be handled in an industrial scale production.
The novel polymerizable monomer, represented by the general formula (1), has fluorine and hydroxyl group coexistent in its hexafluoroisopropanol group. As defined above, R
1
usable in the general formula (1) can be selected from hydrogen atom, halogen atoms, hydrocarbon groups and fluorine-containing alkyl groups. Of these, preferable halogen atoms are fluorine, chlorine and bromine. Preferable hydrocarbon groups are methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, sec-butyl group, tert-butyl group, cyclopentyl group, cyclohexyl group, phenyl group, benzyl group, and phenethyl group. Examples of the fluorine-containing alkyl groups are those containing fluorine atom partially or totally substituted for hydrogen atom of the above-cited alkyl groups. In the case of the hydrocarbon groups and the fluorine-containing alkyl groups, the number of carbon atoms in the molecule is preferably about 1-20, preferably 1-4 from the viewpoint of polymerizability of the monomer. Exemplary fluorine-containing groups are trifluoromethyl group (—CF
3
), trifluoroethyl group (—CH
2
CF
3
), 1,1,1,3,3,3-hexafluoroisopropyl group, heptafluoroisopropyl group, and nonafluoro-n-butyl group (—C
4
F
9
).
As stated above, R
2
usable in the general formula (1) can be a straight-chain or branched alkyl group, a cyclic alkyl group, an aromatic group, or a substituent having at least two of these groups. Furthermore, R
2
is optionally partially fluorinated and optically contains an unsaturated bond(s). Examples of R
2
are straight-chain or branched alkylene groups such as methylene group, ethylene group, isopropylene group and t-butylene group; cyclic groups such as cyclobutene group, cyclohexane group, norbornene group and adamantane group; and aromatic groups such as phenyl group.
Specific examples of the polymerizable monomer (represented by the general formula (1)) are represented by the following general formulas (2)-(5):
wherein R
3
is a hydrogen atom, a hydrocarbon group that is optionally branched, a fluorine-containing alkyl group, or a cyclic group having an aromatic or alicyclic structure, and R
3
optionally contains a bond of an oxygen atom or carbonyl group. If R
3
is a hydrogen atom, the resulting polymer is improved in transparency. However, depending on the use of the resulting polymer, R
3
can be selected from the other groups. Examples of such groups are hydrocarbon groups having a carbon atom number of about 1-20 and optionally having a cyclic structure, such as methyl group, ethyl group, isopropyl group, cyclopropyl group, cyclopentyl group, cyclohexyl group, norbornel group, adamantyl group and benzyl group. Further exemplary oxygen atom-containing groups are open-chain ether groups such as methoxymethyl ether and methoxyethoxymethyl ether; cyclic ether groups such as tetrahydrofuran and tetrahydropyrane; and aromatic groups such as 4-methoxybenzyl group. Further exemplary carbonyl-containing groups are acetyl group, pivaloyl group, tert-butoxycarbonyl group, and benzoyl group. It is possible to protect or modify the carbonyl-containing groups. Its purpose is to provide the polymers, for example, with (a) crosslinking property, (b) positive-type photosensitivity by a photo-induced acid generator, and (c) etching resistance, thereby producing the polymers having a good solubility in organic solvents and alkali aqueous solutions, a high glass transition point, and a heat resistance upon soldering. Thus, R
3
can suitably be selected depending on the use of the polymer.
R
4
in the general formula (3) can be a hydrocarbon group having a
Arai Shoji
Maeda Kazuhiko
Miyazawa Satoru
Tokuhisa Kenji
Central Glass Company Limited
Crowell & Moring LLP
Lipman Bernard
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