Polyimide nonwoven fabric and process for production thereof
First Claim
1. A process for producing a non-woven fabric, comprising the steps of:
- preparing a polyamic acid by polycondensation of reactants consisting of an aromatic tetracarboxylic acid anhydride and an aromatic diamine having a benzoxazole structure in one or more organic solvents, and electro-spinning the polyamic acid to form a polyimide precursor fiber bundle; and
imidizing the polyimide precursor fiber bundle to obtain the non-woven fabric having a fiber diameter in the range of 0.001 μ
m to 100 nm and having a coefficient of linear expansion in the range of −
6 ppm/°
C. to 14 ppm/°
C.;
wherein the aromatic tetracarboxylic acid anhydride is selected from the group consisting ofpyromellitic anhydride,3,3′
,4,4′
-biphenyltetracarboxylic anhydride,4,4′
-oxydiphthalic anhydride,3,3′
,4,4′
-benzophenonetetracarboxylic anhydride,3,3′
,4,4′
-diphenylsulfonetetracarboxylic anhydride, and2,2′
-bis[4-(3,4-dicarboxyphenoxy)phenyl]propanoic anhydride,the aromatic diamine is selected from the group consisting of;
5-amino-2-(p-aminophenyl)benzoxazole,6-amino-2-(p-aminophenyl)benzoxazole,5-amino-2-(m-aminophenyl)benzoxazole,6-amino-2-(m-aminophenyl)benzoxazole,2,2′
-p-phenylenebis(5-aminobenzoxazole),2,2′
-p-phenylenebis(6-aminobenzoxazole),1-(5-aminobenzoxazolo)-4-(6-aminobenzoxazole)benzene,2,6-(4,4′
-diaminodiphenyl)benzo[1,2-d;
5,4-d′
]bisoxazole,2,6-(4,4′
-diaminodiphenyl)benzo[1,2-d;
4,5-d′
]bisoxazole,2,6-(3,4′
-diaminodiphenyl)benzo[1,2-d;
5,4-d′
]bisoxazole,2,6-(3,4′
-diaminodiphenyl)benzo[1,2-d;
4,5-d′
]bisoxazole,2,6-(3,3′
-diaminodiphenyl)benzo[1,2-d;
5,4-d′
]bisoxazole, and2,6-(3,3′
-diaminodiphenyl)benzo[1,2-d;
4,5-d′
]bisoxazole,the polyamic acid has a reduced viscosity of 3.0 dl/g or more, andthe electro-spinning is carried out under the following conditions;
the spinning nozzle has an inside diameter in the range of from 0.1 mm to 3 mm,the applied voltage is in the range of 10 kV to 15 kV, andthe distance between the electrodes is in the range of 5 cm to 20 cm.
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Accused Products
Abstract
A non-woven fabric which is excellent in thermal resistance, mechanical strength, and thermal dimensional stability for applications exposed to high temperature circumstance and has an extremely large surface area and exhibit an excellent filter performance is obtained. The non-woven fabric is composed of polyimide fibers which are obtained by polycondensation of at least an aromatic tetracarboxylic acid and an aromatic diamine having a benzoxazole structure and have a fiber diameter in the range of 0.001 μm to 1 μm. The non-woven fabric is obtained by the steps of preparing a polyamic acid by polycondensation of an aromatic tetracarboxylic acid and an aromatic diamine having a benzoxazole structure, and electro-spinning the polyamic acid to form a polyimide precursor non-woven fabric; and imidizing a polyimide precursor fiber bundle.
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Citations
6 Claims
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1. A process for producing a non-woven fabric, comprising the steps of:
-
preparing a polyamic acid by polycondensation of reactants consisting of an aromatic tetracarboxylic acid anhydride and an aromatic diamine having a benzoxazole structure in one or more organic solvents, and electro-spinning the polyamic acid to form a polyimide precursor fiber bundle; and imidizing the polyimide precursor fiber bundle to obtain the non-woven fabric having a fiber diameter in the range of 0.001 μ
m to 100 nm and having a coefficient of linear expansion in the range of −
6 ppm/°
C. to 14 ppm/°
C.;wherein the aromatic tetracarboxylic acid anhydride is selected from the group consisting of pyromellitic anhydride, 3,3′
,4,4′
-biphenyltetracarboxylic anhydride,4,4′
-oxydiphthalic anhydride,3,3′
,4,4′
-benzophenonetetracarboxylic anhydride,3,3′
,4,4′
-diphenylsulfonetetracarboxylic anhydride, and2,2′
-bis[4-(3,4-dicarboxyphenoxy)phenyl]propanoic anhydride,the aromatic diamine is selected from the group consisting of; 5-amino-2-(p-aminophenyl)benzoxazole, 6-amino-2-(p-aminophenyl)benzoxazole, 5-amino-2-(m-aminophenyl)benzoxazole, 6-amino-2-(m-aminophenyl)benzoxazole, 2,2′
-p-phenylenebis(5-aminobenzoxazole),2,2′
-p-phenylenebis(6-aminobenzoxazole),1-(5-aminobenzoxazolo)-4-(6-aminobenzoxazole)benzene, 2,6-(4,4′
-diaminodiphenyl)benzo[1,2-d;
5,4-d′
]bisoxazole,2,6-(4,4′
-diaminodiphenyl)benzo[1,2-d;
4,5-d′
]bisoxazole,2,6-(3,4′
-diaminodiphenyl)benzo[1,2-d;
5,4-d′
]bisoxazole,2,6-(3,4′
-diaminodiphenyl)benzo[1,2-d;
4,5-d′
]bisoxazole,2,6-(3,3′
-diaminodiphenyl)benzo[1,2-d;
5,4-d′
]bisoxazole, and2,6-(3,3′
-diaminodiphenyl)benzo[1,2-d;
4,5-d′
]bisoxazole,the polyamic acid has a reduced viscosity of 3.0 dl/g or more, and the electro-spinning is carried out under the following conditions; the spinning nozzle has an inside diameter in the range of from 0.1 mm to 3 mm, the applied voltage is in the range of 10 kV to 15 kV, and the distance between the electrodes is in the range of 5 cm to 20 cm. - View Dependent Claims (2, 3, 4, 5, 6)
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Specification