Polyamide and process for producing the same

Details Polyamide and process for producing the same Polyamide and process for producing the same

2000-10-20

2002-01-22

Hampton-Hightower, P. (Department: 1711)

Synthetic resins or natural rubbers -- part of the class 520 ser

Synthetic resins

From carboxylic acid or derivative thereof

C528S170000, C528S322000, C528S327000, C528S335000, C528S336000, C549S291000

Reexamination Certificate

active

06340739

ABSTRACT:

TECHNICAL FIELD
The present invention relates to a polyamide which has a high polarity and a high refractive index and which is useful as a material for producing fibers or plastics; to a process for producing the polyamide; and to an intermediate for producing the polyamide.
BACKGROUND ART
Examples of materials and products prepared from polyamides includes polyamide fiber such as Nylon, polyamide resin employed as engineering plastics, and aramid fiber such as Kevlar fiber. These polyamides are widely employed in such applications as general purpose fiber materials, elastic fiber materials, high-strength fiber materials, and plastics.
However, there is a demand for the development of a polyamide that exhibits enhanced properties. One example is swimwear. When white swimwear fabricated with a conventional nylon is worn, the body of the wearer can be seen through the swimwear due to the proximity of the refractive index of water and that of nylon. Meanwhile, swimwear fabricated with a conventional high-refractive-index polyamide is disadvantaged by feeling uncomfortable against the skin and by having an unsatisfactory appearance. Thus, there is a demand for a polyamide that can provide a fibersatisfying both a high refractive index and having a good sensation against the skin. In addition, conventional polyamide has poor biodegradability, and thus a polyamide having improved biodegradability is demanded.
In view of the foregoing, an object of the present invention is to provide a polyamide having functions such as a high refractive index, high strength, and biodegradability.
DISCLOSURE OF THE INVENTION
In order to overcome the aforementioned drawbacks, the present inventors have conducted extensive studies on dicarboxylic acids which can serve as raw materials for producing polyamides, and have found that polyamides which are produced by polycondensing 2H-pyran-2-one-4,6-dicarboxylic acid and a variety of diamines exhibit high mechanical strength and have a high refractive index and polarity and that a 2H-pyran-2-one ring has excellent biodegradability. The present invention has been accomplished on the basis of these findings.
Accordingly, the present invention provides a polyamide having a structural repeating unit represented by formula (1)
(wherein R
1
represents a divalent hydrocarbon residue optionally having in the structure a heteroatom having no active hydrogen), and a process for producing the same.
The present invention also provides a polyamide having structural repeating units represented by formula (1) and (2):
(wherein R
2
represents a divalent hydrocarbon residue optionally having in the structure a heteroatom having no active hydrogen and R
1
represents the same as defined above), and a process for producing the same.
The present invention further provides 2H-pyran-2-one-4,6-dicarboxylic acid derivatives represented by formula (3):
(wherein X
1
represents an alkoxy group or a halogen atom). Among the monomers for producing the polyamide of the present invention, the above carboxylic acid derivatives are novel compounds.
BEST MODES FOR CARRYING OUT THE INVENTION
The polyamides of the present invention have a structural repeating unit represented by formula (1) or structural repeating units represented by formulas (1) and (2). In formulas (1) and (2), each of R
1
and R
2
represents a divalent hydrocarbon residue optionally having in the structure a heteroatom having no active hydrogen. Among divalent hydrocarbon residues, preferred are R
3
and R
3
—(OR
3
)
1
—, wherein 1 is a number between 1 and 4; and R
3
represents a C2-C24 saturated or unsaturated divalent hydrocarbon residue, with a C2-C24 linear chain or branched chain alkylene group, a C3-C8 cycloalkane divalent residue, and a C5-C10 aromatic hydrocarbon divalent residue being particularly preferred. Examples of more preferred R
1
and R
2
include a trimethylene group, a propylene group, a tetramethylene group, a hexamethylene group, an octamethylene group, a decamethylene group, a dodecamethylene group, a phenylene group, a tolylene group, a xylylene group, a naphthalene group, a cyclohexylene group, and —CH
2
CH
2
(OCH
2
CH
2
)
2
—. These hydrocarbon residues may have a substituent having no active hydrogen such as an alkoxy (preferably C1-C6) group, an alkanoyl (preferably C2-C6) group, an alkyl (preferably C1-C6) group, an aryl (preferably C6-C14) group, or an aralkyl (preferably C7-C18) group.
In the polyamide having structural repeating units represented by formulas (1) and (2), these two types of units may be linked in a block manner (i.e., block copolymer) or randomly (i.e., random copolymer).
No particular limitation is imposed on the molecular weight of the polyamide of the present invention, and it varies in accordance with use. Typically, the molecular weight based on the number average molecular weight is preferably 10,000-200,000, more preferably 40,000-100,000. The molecular weight is particularly preferably 60,000-80,000 in view of moldability from a solution or melt thereof and development of physical properties such as mechanical strength.
The polyamide of the present invention having a structural repeating unit represented by formula (1) may be produced in accordance with the following reaction scheme:
(wherein X
2
represents a hydroxyl group, an alkoxy group, or a halogen atom; R
1
is the same as defined above).
Specifically, a 2H-pyran-2-one-4,6-dicarboxylic acid derivative (4) and a diamine (5) are subjected to polycondensation reaction, to thereby produce the polyamide of the present invention (1).
Among dicarboxylic monomers (4), a monomer in which X
2
is an alkoxy group and a monomer in which X
2
is a halogen atom are novel compounds. The compounds can be produced by converting 2H-pyran-2-one-4,6-dicarboxylic acid represented by formula (4) (wherein X is OH) to an ester or an acid halide thereof through a customary method. Among alkoxy groups for X
2
, a lower alkoxy group is preferred, with a C1-C6 alkoxy group being particularly preferred in view of reactivity to diamines. Among halogen atoms, a chlorine atom and a bromine atom are preferred.
Appropriate types of polycondensation may be employed in accordance with dicarboxylic species (4). For example, dehydration-polycondensation is preferably employed when a dicarboxylic species (4) in which X
2
is a hydroxyl group is used. Similarly, alcohol-removing-polycondensation is preferably employed when a dicarboxylic derivative (4) in which x
2
is an alkoxyl group is used and interfacial-polycondensation is preferably employed when a dicarboxylic derivative (4) in which X
2
is a halogen atom is used.
In dehydration-polycondensation, for example, dicarboxylic acid (4) and a diamine (5) are mixed at a mol ratio of approximately 1:1, and the mixture is heated in the presence of an optional dehydration-condensing agent such as dicyclohexylcarbodiimide.
In alcohol-removing-polycondensation, for example, a dicarboxylic acid diester (4) and a diamine (5) are mixed at a mol ratio of approximately 1:1, and the mixture is heated.
Interfacial-polycondensation is carried out, for example, by employing an interface between a solution of a dicarboxylic dihalide (4) in halohydrocarbon and an aqueous solution containing alkali hydroxide and a diamine (5). Examples of halohydrocarbon include tetrachlorocarbon and chloroform. Sodium hydroxide is preferably used as the alkali hydroxide.
The polyamide of the present invention having structural repeating units represented by formulas (1) and (2) may be produced in accordance with the following reaction scheme:
(wherein X
3
represents a hydroxyl group, an alkoxy group, or a halogen atom; m and n are integers; and R
1
, R
2
, and X
2
are the same as defined above).
Specifically, a 2H-pyran-2-one-4,6-dicarboxylic acid derivative (4), a diamine (5), and a dicarboxylic acid derivative (6) are subjected to polycondensation reaction, to thereby produce the polyamide of the present invention having structural repeating units represented by formulas (1) and (2).
Among alkoxy groups for X
3

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