Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From phenol – phenol ether – or inorganic phenolate
Reexamination Certificate
2000-12-15
2003-09-09
Raymond, Richard L. (Department: 1624)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From phenol, phenol ether, or inorganic phenolate
C562S480000, C562S490000
Reexamination Certificate
active
06617414
ABSTRACT:
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a monomer used for producing polybenzazole formable into a fiber and a film having high strength, high elastic modulus and high heat resistance. More particularly, the present invention relates to aromatic diamine/aromatic dicarboxylate having high polymerizability.
BACKGROUND OF THE INVENTION
Polybenzazole represented by polybenzoxazole and polybenzothiazole has been increasingly used for wider applications, such as reinforcing materials for rubber and plastic, industrial materials (e.g., heat resistant felt), and protective purposes (e.g., protective cloth for fire fighter and safety gloves), because it shows markedly high dynamic properties, heat resistance and flame resistance, among organic substances.
A typical production method of polybenzazole comprises subjecting aromatic diamine, such as 4,6-diamino-1,3-benzenediol, 2,5-diamino-1,4-benzenedithiol and the like, and aromatic dicarboxylic acid, such as terephthalic acid, naphthalenedicarboxylic acid, biphenyldicarboxylic acid and the like, to condensation polymerization in a solvent having a dehydrating effect, such as polyphosphoric acid and the like.
Aromatic diamine, which is a monomer of polybenzazole, is easily oxidized and handled in the form of an inorganic acid salt, which is more stable against oxidation and generally used as hydrochloride. When aromatic diamine hydrochloride is used for producing polybenzazole, however, a poisonous hydrogen chloride gas is generated in a large amount in an early stage of condensation polymerization. The generation of gas during reaction causes inflation of reaction volume and lowers the volume efficiency of a reactor, which is unpreferable from the aspect of productivity.
As a polybenzazole monomer free of gas generation, U.S. Pat. No. 5,276,128 discloses aromatic diamine/aromatic dicarboxylate. This is a monomer obtained by forming a salt from aromatic diamine and aromatic dicarboxylic acid in a 1:1 ratio, which does not contain a component that generates a gas, such as hydrogen chloride. When compared to the use of two kinds of monomers of aromatic diamine hydrochloride and aromatic dicarboxylic acid, moreover, weighing and charging is advantageously easier.
However, the aromatic diamine/aromatic dicarboxylate disclosed in the above-mentioned U.S. Pat. No. 5,276,128 does not have sufficient quality. The aromatic diamine/aromatic dicarboxylate has a chemical composition ratio of aromatic diamine and aromatic dicarboxylic acid of 1:1. If the polymerization degree is not controlled by the addition of a chain-end terminator and the like, polybenzazole having an extremely high polymerization degree should be obtained. However, the above-mentioned aromatic diamine/aromatic dicarboxylate is colored in pink or purple. This is considered to be attributable to partial decomposition of the constituent component, aromatic diamine.
As a result, the chemical composition of aromatic diamine and aromatic dicarboxylic acid is to be deviated, which prevents the polymerization degree of polybenzazole from increasing and reduces its viscosity. In an example of the above-mentioned USP, for instance, 4,6-diamino-1,3-benzenediol/terephthalate produces polybenzazole having an intrinsic viscosity of up to about 40 dl/g, and 2,5-diamino-1,4-benzenedithiol/terephtalate produces polybenzazole having an intrinsic viscosity of up to about 13 dl/g. In an example of EP 0805173A, a reaction is carried out at a low temperature for a long time to afford a polymer having a somewhat higher intrinsic viscosity of 48.5 dl/g than in the above-mentioned USP, from 4,6-diamino-1,3-benzenediol/terephtalate. However, the polymerization degree of the polymer is not sufficient.
When polybenzazole is produced from two kinds of monomers of aromatic diamine hydrochloride and aromatic dicarboxylic acid, a yellow polymer is generally obtained. When conventional aromatic diamine/aromatic dicarboxylate is used, only a polymer of a lower grade, which is colored in black to dark brown or dark purple to reddish purple, can be obtained.
In addition, conventional aromatic diamine/aromatic dicarboxylate shows markedly inferior stability against oxidation and heat as compared to aromatic diamine hydrochloride, which prevents long-term storage. Also, it frequently suffers from thermal degradation during production of polybenzazole. This has a consequence that the hue of the polymer becomes poor and the polymerization degree decreases.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to overcome low polymerizability, coloring of polymer and the like of conventional aromatic diamine/aromatic dicarboxylate, and to provide a monomer having a quality suitable for the production of polybenzazole, and a production method of aromatic diamine/aromatic dicarboxylate having such quality.
Such objects can be achieved by the present invention, wherein aromatic diamine/aromatic dicarboxylate in a particulate state and having a specific particle diameter and whiteness is polymerized to give polybenzazole having superior high polymerization degree and superior hue.
That is, the present invention provides aromatic diamine/aromatic dicarboxylate of the following formula (I)
NH
2
—Ar
1
—NH
2
.HOOC—Ar
2
—COOH (I)
wherein Ar
1
is a group of the following formula (a) or (b)
wherein each Z is independently an oxygen atom or a sulfur atom, and
Ar
2
is a group of any of the following formulas (c)-(f)
wherein R
1
and R
2
are each independently a hydrogen atom, a methyl group or a hydroxyl group,
which is in the form of particles having a median diameter of 5-100 &mgr;m and whiteness of not less than 75.
Preferably, the above-mentioned aromatic diamine/aromatic dicarboxylate has a water content of not more than 3000 ppm, and preferably contains tin(II) or iron(II) in a proportion of 0.1-5.0 mol %.
The present invention also provides a production method of the above-mentioned aromatic diamine/aromatic dicarboxylate, which comprises adding, for mixing, an aqueous solution of aromatic diamine hydrochloride of the following formula (II)
NH
2
—Ar
1
—NH
2
.2HCl (II)
wherein Ar
1
is as defined above, to an aqueous solution of alkali metal aromatic dicarboxylate of the following formula (III)
MOOC—Ar
2
—COOM (III)
wherein Ar
2
is as defined above and M is an alkali metal, under the following conditions (1) and (2):
(1) 1.0-1.2 moles of the aromatic diamine hydrochloride is used per 1 mole of the alkali metal aromatic dicarboxylate, and
(2) a temperature during the addition is not less than 70° C. and not more than 100° C.
In addition, the present invention provides a production method of polybenzazole, which comprises using the above-mentioned aromatic diamine/aromatic dicarboxylate.
DETAILED DESCRIPTION OF THE INVENTION
The aromatic diamine/aromatic dicarboxylate of the present invention can be represented by the above-mentioned formula (I).
Examples of aromatic diamine in the aromatic diamine/aromatic dicarboxylate of the above-mentioned formula (I) include 4,6-diamino-1,3-benzenediol, 2,5-diamino-1,4-benzenediol, 4,6-diamino-1,3-benzenedithiol, 2,5-diamino-1,4-benzenedithiol and the like.
Examples of aromatic dicarboxylic acid in the aromatic diamine/aromatic dicarboxylate of the above-mentioned formula (I) include terephthalic acid, 2-methylterephthalic acid, monohydroxyterephthalic acid, dihydroxyterephthalic acid, phthalic acid, naphthalenedicarboxylic acid, biphenyldicarboxylic acid and the like.
In view of the easiness of obtaining a starting material, the aromatic diamine/aromatic dicarboxylate of the above-mentioned formula (I) is preferably that wherein aromatic diamine thereof is 4,6-diamino-1,3-benzenediol or 2,5-diamino-1,4-benzenedithiol, and aromatic dicarboxylic acid thereof is terephthalic acid or 2-methylterephthalic acid, with preference given to 4,6-diamino-1,3-benzenediol/terephtalate, 4,6-diamino-1,3-benzenediol/2-methylterephtalate and 2,5-diamino-1,4-benzenedithiol/terephtalate.
In the present invention, two o
Hotta Kiyoshi
Kubota Fuyuhiko
Morrison & Foerster / LLP
Raymond Richard L.
Toyo Boseki Kabushiki Kaisha
Tucker Zachary C.
LandOfFree
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