Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From phenol – phenol ether – or inorganic phenolate
Reexamination Certificate
1999-11-19
2001-08-28
Hampton-Hightower, P. (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From phenol, phenol ether, or inorganic phenolate
C528S125000, C528S126000, C528S128000, C528S172000, C528S173000, C528S176000, C528S179000, C528S183000, C528S185000, C528S188000, C528S220000, C528S229000, C528S350000, C528S353000, C428S411100, C428S473500
Reexamination Certificate
active
06281323
ABSTRACT:
BACKGROUND OF THE INVENTION
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1
. Field of the Invention
The present invention relates to terminal-modified imide oligomers obtained by reacting a 2,3,3′,4′-biphenyltetracarboxylic acid compound, an aromatic diamine compound and 4-(2-phenylethynyl)phthalic anhydride, and to their cured products.
Composite materials obtained as cured products by heat curing fiber-reinforced prepregs whose matrix resins are terminal-modified imide oligomers according to the present invention have excellent heat resistance and mechanical properties, and are particularly suitable for use in devices for the aeronautical and space industries.
2. Description of the Related Art
Cured products of terminal-modified imide oligomers exhibit excellent heat resistance and have long been known as matrix resins for molded products and fiber-reinforced composite materials.
As examples of such terminal-modified imide oligomers, Japanese Unexamined Patent Publication No. 64-54029 describes terminal-modified imide oligomers obtained by reacting a 2,3,3′,4′-biphenyltetracarboxylic acid compound, an aromatic diamine compound and an unsaturated dicarboxylic acid such as nadic anhydride or an unsaturated monoamine compound such as propargylamine; Japanese Unexamined Patent Publication No. 64-54030 describes terminal-modified imide oligomers obtained by reacting a 3,3′,4,4′-biphenyltetracarboxylic acid compound, an aromatic diamine compound and an unsaturated dicarboxylic acid such as nadic anhydride or an unsaturated monoamine compound such as propargylamine; and Japanese Unexamined Patent Publication No. 3-292130 describes a process for producing molded products of terminal-modified imide oligomers obtained by reacting a biphenyltetracarboxylic acid compound, an aromatic diamine compound and an unsaturated dicarboxylic acid such as maleic anhydride or an unsaturated monoamine compound such as propargylamine.
These terminal-modified imide oligomers modified with unsaturated monoamine compounds and terminal-modified imide oligomers modified with nadic anhydride all have low heat resistance as cured products.
There have recently been proposed, therefore, terminal-modified imide oligomers modified with 4-(phenylethynyl)phthalic anhydride.
For example, terminal-modified imide oligomers which are oligomers of 1,4-diaminobenzene and 2,2′-bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride and are terminal-modified with 4-(phenylethynyl)phthalic anhydride are described in “Polymer”, 35, 4865 (1994), and terminal-modified imide oligomers obtained by reacting 3,3′,4,4′-biphenyltetracarboxylic dianhydride, 1,1,1,3,3,3-hexafluoro-2,2-bis(3,4-dicarboxyphenyl)propane dianhydride, p-phenylenediamine and 4-(phenylethynyl)phthalic anhydride are described in “Polymer”, 35, 4874 (1994).
However, these publicly known terminal-modified imide oligomers make use of special compounds as the essential aromatic tetracarboxylic dianhydrides.
BRIEF SUMMARY OF THE INVENTION
It is an object of the invention to provide novel, highly practical terminal-modified imide oligomers that give cured products with satisfactory heat resistance and mechanical properties (for example, elastic modulus, tensile strength and elongation), and also cured products thereof.
Specifically, the present invention relates to terminal-modified imide oligomers obtained by reacting a 2,3,3′,4′-biphenyltetracarboxylic acid compound, an aromatic diamine compound and 4-(2-phenylethynyl)phthalic anhydride, and which are represented by the following formula:
where X is an aromatic diamine residue and n is an integer,
with an inherent viscosity (&eegr;inh, 30° C., 0.5 g/100 ml solvent, solvent: N-methyl-2-pyrrolidone) of 0.05-1, as well as to cured products comprising the terminal-modified imide oligomers alone or as composite materials with fibrous reinforcing materials.
DETAILED DESCRIPTION OF THE INVENTION
The terminal-modified imide oligomers of the invention are imide oligomers obtained by reacting a 2,3,3′,4′-biphenyltetracarboxylic acid compound, an aromatic diamine compound and 4-(2-phenylethynyl)phthalic anhydride (hereunder abbreviated simply to “PEPA”), preferably in a solvent, where the equivalents for the total of each of the acid groups and equivalents for each amino group are approximately equal; the terminal-modified imide oligomers have an acetylenic addition-polymerizable unsaturated terminal group based on 4-(2-phenylethynyl)phthalic anhydride at either end (preferably both ends) of the imide oligomer and an imide bond on the imide oligomer main chain, the inherent viscosity is 0.05-1, preferably 0.05-0.5 and especially about 0.05-0.3, and they are relatively low molecular weight solids (powders) at normal temperature.
Terminal-modified imide oligomers with a melt viscosity in the range of 10 to 1 million poise, as the minimum melt viscosity before curing, are preferred. Also, terminal-modified imide oligomers with a post-curing glass transition point (Tg) of 300° C. or higher and a post-curing flexural strength of 1300 kgf/cm
2
or greater are preferred.
The minimum melt viscosity mentioned above is the temperature-dependent minimum value of the melt viscosity of the terminal-modified imide oligomer, which undergoes viscosity decrease with increasing temperature and viscosity increase due to the curing reaction.
The 2,3,3′,4′-biphenyltetracarboxylic acid compound is 2,3,3′,4′-biphenyltetracarboxylic acid, 2,3,3′,4′-biphenyltetracarboxylic dianhydride (a-BPDA), or a lower alcohol ester, a salt or another derivative of 2,3,3′,4′-biphenyltetracarboxylic acid, with 2,3,3′,4′-biphenyltetracarboxylic dianhydride being ideal.
According to the invention, a portion of the 2,3,3′,4′-biphenyltetracarboxylic acid compound (preferably 50 mole percent or less, more preferably 30 mole percent or less, and even more preferably 25 mole percent or less) may be replaced with another aromatic tetracarboxylic acid compound, for example 3,3′,4,4′-biphenyltetracarboxylic dianhydride (s-BPDA), 3,3′,4,4′-benzophenonetetracarboxylic dianhydride (BTDA), pyromellitic dianhydride, 2,2-bis(3,4-dicarboxyphenyl)methane or bis(3,4-dicarboxyphenyl) ether dianhydride.
As aromatic diamine compounds there may be mentioned 1,4-diaminobenzene, 1,3-diaminobenzene, 1,2-diaminobenzene, 2,6-diethyl-1,3-diaminobenzene, 4,6-diethyl-2-methyl-1,3-diaminobenzene, 3,5-diethyltoluene-2,4-diamine, 3,5-diethyltoluene-2,6-diamine, 4,4′-diaminodiphenyl ether (4,4-ODA), 3,4′-diaminodiphenyl ether (3,4-ODA), 3,3′-diaminodiphenyl ether, 3,3′-diaminobenzophenone, 4,4′-diaminobenzophenone, 3,3′-diaminodiphenylmethane, 4,4′-diaminodiphenylmethane, bis(2,6-diethyl-4-aminophenyl)methane, 4,4′-methylene-bis(2,6-diethylaniline), bis(2-ethyl-6-methyl-4-aminophenyl)methane, 4,4′-methylene-bis(2-ethyl-6-methylaniline), 2,2-bis(3-aminophenyl)propane, 2,2-bis(4-aminophenyl)propane, 1,3-bis(4-aminophenoxy)benzene (TPE-R), 1,3-bis(3-aminophenoxy)benzene, 1,4-bis(4-aminophenoxy)benzene, 1,4-bis(3-aminophenoxy)benzene, benzidine, 3,3′-dimethylbenzidine, 2,2-bis(4-aminophenoxy)propane, 2,2-bis(3-aminophenoxy)propane and 2,2-bis[4′-(4″-aminophenoxy)phenyl]hexafluoropropane, any of which may be used alone or in combinations of two or more.
Particularly preferred aromatic diamine compounds are 4,4′-diaminodiphenyl ether (4,4-ODA), 3,4′-diaminodiphenyl ether (3,4-ODA) and 1,3-bis(4-aminophenoxy)benzene (TPE-R).
According to the invention, 4-(2-phenylethynyl)phthalic anhydride is used as the unsaturated acid dianhydride for terminal modification (end capping).
The 4-(2-phenylethynyl)phthalic anhydride is preferably used at a proportion in the range of 5-200 mole percent, and especially 5-150 mole percent, with respect to the total acid.
As the solvent there may be mentioned N-methyl-2-pyrrolidone (NMP), N,N-dimethylformamide, N,N-dimethylacetamide (DMAc), N,N-diethylac
Hasegawa Masatoshi
Yamaguchi Hiroaki
Yokota Rikio
Hampton-Hightower P.
Schnader Harrison Segal & Lewis LLP
Ube Industries Ltd.
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