Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From phenol – phenol ether – or inorganic phenolate
Reexamination Certificate
2000-03-20
2001-06-26
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
C528S026000, C528S028000, C528S033000, C528S038000, C528S125000, C528S126000, C528S128000, C528S171000, C528S172000, C528S173000, C528S174000, C528S175000, C528S176000, C528S179000, C528S183000, C528S185000, C528S188000, C528S220000, C528S229000, C528S350000, C528S351000, C528S353000, C525S420000, C525S422000, C525S431000, C525S436000
Reexamination Certificate
active
06252033
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a method for preparing polyamic acid, a precursor of polyimide, which is superior in thermal resistance and high-temperature adhesive properties and polyimide therefrom. More particularly, the present invention relates to a method for preparing three-dimensional molecular structures of polyamic acid and polyimide.
BACKGROUND ART
Polyimide is a high heat-resistant resin which is typically prepared by reacting dianhydride with diamine in an organic solvent and subjecting the resulting polyamic acid, a precursor of polyimide, to thermal or chemical imidization.
With excellent in thermal resistance, chemical resistance, electrical insulation, and mechanical properties, polyimide resins find numerous applications in the electric and electronic appliance, adhesive, composite material, fiber, and film industries.
By virtue of its linear backbone structure which allows chains to be packed at a high density and by virture the rigidity of the imide ring itself, polyimide can show superior thermal resistance. But, such structural features make it difficult for the polyimide to dissolve in solvents and to be melted by heating, so that the polyimide is poor in processability and adhesiveness to other materials.
Particularly, the polyimide which is specialized to be used in areas where high temperature stability is required, as in the production of films, has a linear backbone structure such that the packing density of polymer chains is high, largely determining the thermal resistance of the polyimide. Commercially available polyimide films, exemplified by Kapton and Upilex, typically exhibit such structures. Kapton is known to be prepared from pyromellitic dianhydride (PMDA) and oxydianiline (ODA) monomers while Upilex can be prepared from 3,3′,4,4′-biphenyltetracarboxylic acid dianhydride (BPDA) and para-phenylenediamine (PPD) monomers. Also, it is known that a polyimide resin which is of higher thermal resistance can be obtained from a combination of PMDA and PPD monomers. However, very high rigidity and chain packing density of these polyimide resins brings about a bad effect upon their processability, flowability at high temperatures and adhesive properties.
To improve such problems, many attempts have been made, including introduction of polar groups into polymer backbones or side chains, introduction of bulky linking groups or side chains into backbones, and improvement of polymer backbone flexibility.
An improvement in the solubility of polyimide resins can be found in
Macromolecules,
1994, 27, 1117, by Kurosaki et al., in which alicyclic acid anhydride is used as a monomer to prepare a soluble polyimide coating solution. Cyclic diamine is also used to prepare a soluble polyimide as disclosed in
Polymer Chem. Ed.,
1993, 31, 2345-2351, by Qin Jin et al. However, most of the soluble polyimides modified in these manners suffer from a difficulty in practical use because they have significantly degraded thermal stability and mechanical properties.
In order to improve the solubility and adhesiveness properties of polyimide, there was suggested the introduction of siloxane structures of diamine compounds into polymer backbones as in U.S. Pat. Nos. 5,859,181, 5,942,592 and 5,094,919. No matter how improved it is, the solubility property resulting from the introduction of siloxane structures of diamine compounds falls within the scope of the conventional polyimide films. In addition, the presence of a great amount of the siloxane structures in the polymer deteriorates the thermal resistance and mechanical properties of the polymer. It is also difficult to introduce a great amount of the siloxane structures into the polymer.
SUMMARY OF THE INVENTION
Therefore, it is an object of the present invention to overcome the above problems encountered in prior art and to provide a method for preparing polyamic acid and polyimide, which both have such three-dimensional molecular structures that a significant improvement can be brought about in solvent solubility, thermal resistance, mechanical properties, and adhesive properties onto various substrates, thereby making the polymers suitable for use in adhesives or adhesive tapes for electronic parts.
Based on the present invention, the above object may be accomplished by a provision of a method for preparing polyamic acid and polyimide, which comprises reacting a mixture containing: at least one tetracarboxylic dianhydride; at least one aromatic diamine; at least one diamine with a siloxane structure, represented by the following general formula I:
wherein R4 is an alkylene group containing 1-20 carbon atoms and n′ is the number of a recurring unit from 1 to 20; and
at least one alkyl or aryl cyclohexylidene dianiline represented by the following general formula II or III:
wherein R represents —CH
3
, —CH
2
CH
3
, —C(CH
3
)
2
(CH
2
CH
3
), or a phenyl group.
DETAILED DESCRIPTION OF THE INVENTION
Having advantages over a linear molecular structure of polyimide in terms of physical properties, including thermal resistance, mechanical properties, adhesive properties and the like, a three-dimensional molecular structure of polyamic acid or polyimide is prepared by employing a siloxane structure of diamine and an alkyl or acyl cyclohexylidene dianiline compound, along with conventionally used aromatic diamine.
As typical examples, the tetracarboxylic dianhydride useful in the present invention is referred to compounds of the following general formula IV:
wherein R1 represents —O—, —CO—, —SO
2
—, —C(CF
3
)
2
—, an alkylene group, an alkylene bicarbonyl group, a phenylene group, a phenylene alkylene group, or a phenylene dialkylene group; n4 is 0 or 1; and n5 is 0 or 1 and n6 is 1 or 2 under the condition that n5+n6=2.
Concrete examples of the aromatic tetracarboxylic dianhydrides of the general formula IV include pyromellitic dianhydride, 3,3′,4,4′-benzophenonetetracarboxylic dianhydride, 3,3′,4,4′-biphenylic dianhydride, 2,3,3′,4′-biphenyltetracarboxylic dianhydride, 2,2′,6,6′-biphenyltetracarboxylic dianhydride, 2,3,6,7-naphthalenetetracarboxylic dianhydride, 1,2,5,6-naphthalenetetracarboxylic dianhydride, 2,2-bis(3,4-dicarboxyphenyl)propane dianhydride, bis(3,4-dicarboxyphenyl)sulfone dianhydride, bis(3,4-dicarboxyphenyl)ether dianhydride, 3,4,9,10-phenylenetetracarboxylic dianhydride, naphthalene-1,2,4,5-tetracarboxylic dianhydride, naphthalene-1,4,5,8-tetracarboxylic dianhydride, benzene-1,2,3,4-tetracarboxylic dianhydride, and ethylene glycol bis(anhydromellitate). These compounds may be used alone or in combinations.
In addition to the above-mentioned aromatic tetracarboxylic dianhydride, aliphatic or alicyclic structures of tetracarboxylic acid may be used within such a range that the polyamic acid or polyimide to be synthesized would not have a deteriorated thermal resistance.
Examples of such aliphatic or alicyclic structures of tetracarboxylic acid include 5-(2,5-diorthotetrahydrol)-3methyl-3-cyclohexane-1,2-dicarboxylic anhdride, 4-(2,5-diorthotetrahydrofuran-3-yl)tetralin-1,2-dicarboxylic anhydride, but-cyclo(2,2,2)-7-en-2,3,5,6-tetracarboxy dianhydride, and 1,2,3,4-cyclopentane tetracarboxy dianhydride and these compounds may be used alone or in combinations.
Concrete examples of the aromatic diamine useful in the present invention include 3,3′-diaminobiphenyl, 3,4′-diaminobiphenyl, 4,4′-diaminobiphenyl, 3,3′ diaminodiphenylmethane, 3,4′ diaminodiphenylmethane, 4,4′-diaminodiphenylmethane, 2,2-(3,3′-diaminodiphenyl)propane, 2,2-(3,4′-diaminodiphenyl)propane, 2,2-(4,4′-diaminodiphenyl)propane, 2,2-(3,3′-diaminodiphenyl)hexafluoropropane, 2,2-(3,4′-diaminodiphenyl)hexafluoropropane, 2,2-(4,4′-diaminodiphenyl)hexafluoropropane, 3,3′-oxydianiline, 3,4′-oxydianiline, 4,4′-oxydianiline, 3,3′-diaminodiphenylsulfide, 3,4′-diaminodiphenylsulfide, 4,4′-diaminodiphenylsulfide, 3,3′-diaminodiphenylsulfone, 3,4&pr
Chang Kyeong Ho
Kim Soon Sik
Kweon Jeong Min
Lee Kyung Rok
Hampton-Hightower P.
Harrison & Egbert
Saehan Industries Incorporation
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