Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From carboxylic acid or derivative thereof
Reexamination Certificate
2000-02-25
2001-11-20
Hampton-Hightower, P. (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From carboxylic acid or derivative thereof
C528S010000, C528S026000, C528S035000, C528S038000, C528S125000, C528S126000, C528S128000, C528S170000, C528S171000, C528S172000, C528S173000, C528S176000, C528S183000, C528S188000, C528S220000, C528S229000, C528S350000
Reexamination Certificate
active
06320019
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 and, more particularly, to a method for preparing three-dimensional molecular structures of polyamic acid and polyimide.
BACKGROUND ART
Typically, polyimide is prepared through the thermal or chemical imidization of polyamic acid, a precursor of polyimide, which can be obtained by reacting dianhydride with diamine in an organic solvent.
Because of its 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 as well as the rigidity of the imide ring itself, polyimide can show superior thermal resistance. Particularly, the polyimide which is specialized to be used in areas where high temperature stability is required, such 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.
No mater how improved it is, the thermal resistance of such linear structures falls within the scope of the conventional polyimide films. An increase in molecular weight of a polyimide film with the aim of improving its thermal properties results in deteriorating its mechanical properties such as flexibility. Various attempts have been made to improve the thermal resistance of polyimide.
For example, Japanese Pat. No. 63-254131 recruits PPD into the polyimide structure prepared from PMDA and ODA, such as Kapton. However, the resulting film suffers from a disadvantage of being poorer in mechanical strength as the content of PPD is higher. In addition, there is found to exist a limit of increasing only the thermal resistance without deteriorating the mechanical properties.
Another technique to overcome the problems that linear structures of polyimide have can be referred to U.S. Pat. No. 5,231,162 in which tri- or tetra-amine is introduced into aromatic diamine with the aim of converting the linear structure into a three-dimensional molecular structure through gelation, whereby both the thermal properties and the mechanical properties can be improved. Resulting from the use of aromatic tetracarboxylic dianhydride and aromatic diamine only, a deficiency in flexibility is found in the film. In addition, the gelation causes the polyamic acid and the polyimide to decrease in solubility, thus making the processability of the resins poor.
With respect to the polyamic acid or polyimide which is used as an adhesive material, its adhesiveness at high temperatures is dependent on the flowability at such temperatures. Introduction of ether into the main chain of the polymer brings about a decrease in its glass transition temperature, thus enabling an improvement in the high-temperature adhesiveness, but a decrease in its thermal resistance, as well, thus making the reliability poor for a process which is carried out with the adhesive.
U.S. Pat. Nos. 4,847,349 and 5,406,124, disclose thermoplastic adhesives based on the diamine containing two or more ether groups which are introduced among three or four phenyl rings. The adhesives show an improvement in high-temperature flowability, but suffer from a disadvantage of being lower in thermal resistance.
SUMMARY OF THE INVENTION
Therefore, it is an object of the present invention to overcome the above problems encountered in the 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 the flowability at high temperatures while guaranteeing the thermal resistance and mechanical properties inherent to the polymers, thereby making the polymers suitable for use in thermal resistance film and high temperature adhesives.
Based on the present invention, the above object could 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 polyamino compound represented by the following general formula II or III:
wherein A1 is selected from the group consisting of:
A2 is selected from the group consisting of:
wherein R represents —O—, —CH
2
—, —CO—, or —SO
2
—;
n1 is an integer of 0 to 4; n2 is an integer of 0 to 3; x represents an acid; and q is the base number of the acid.
DETAILED DESCRIPTION OF THE INVENTION
To have 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 a compound having a polyfunctional amino group such as a tri- or a tetra-amino group, along with conventionally used aromatic diamine. According to the content of the polyfunctional amino group, desired properties of the polyamic acid or polyimide can be obtained.
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′-biphenyltetracarboxylic 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 deteriorated in 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&prime
Chang Kyeong Ho
Kim Soon Sik
Kweon Jeong Min
Lee Kyung Rok
Hampton-Hightower P.
Harrison & Egbert
Saehan Industries Incorporation
LandOfFree
Method for the preparation of polyamic acid and polyimide does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method for the preparation of polyamic acid and polyimide, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method for the preparation of polyamic acid and polyimide will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2606875