Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From carboxylic acid or derivative thereof
Patent
1992-08-12
1995-01-03
Kight, III, John
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From carboxylic acid or derivative thereof
528338, 528339, 528340, 528347, 428395, 4284744, C08G 6926
Patent
active
053788001
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to copolyamides of terephthalic acid, optionally containing isophthalic acid, and mixtures of a diamine e.g. hexamethylene diamine, and 2-methyl-1,5-pentamethylene diamine, and especially to copolyamides having melting points of at least 280.degree. C., and in embodiments of greater than 300.degree. C.
Polymers formed from terephthalic acid and diamines are known in the art. For instance. U.S. Pat. No. 2,752,328 of E. E. Magat, which issued Jun. 26, 1956 describes a polymer formed from terephthalic acid and a methyl-substituted diamine having from 6 to 8 carbon atoms in the hydrocarbon chain of the diamine. It is disclosed that corresponding polymers formed from 3-methyl-pentamethylene diamine were spinnable polymers but the fibres obtained were weak and brittle. The patent does not disclose copolymers. UK Patent 914 456 of W. R. Grace & Co., published Jan. 02, 1963 discloses similar polymers formed from ethyl-substituted diamines.
Japanese patent publication 82-41027 of Toyo Rayon, published Aug. 23, 1969 discloses a method for the manufacture of polyamides from terephthalic acid and pentamethylene diamines having methyl substituents on the hydrocarbon chain. Reference is made to the process described in the aforementioned patent of Magat. The Japanese reference exemplifies the polymerization of 2-methyl pentamethylene diamine and terephthalic acid in the presence of water in a sealed system.
Japanese published patent application (Kokai) 61-162550 of K. Hikami et al, published Jul. 23, 1986 discloses polyamides formed from 0.4-0.6 mole of aromatic diamines and/or aromatic carboxylic acids per mole of polyamidemonomer forming composition, which have melting points of 250.degree.-300.degree. C. If the polyamide is formed from both terephthalic acid and isophthalic acid, then the ratio of those acids must be in the range of 4:6 to 6:4. A number of diamines are disclosed, including 2-methyl pentamethylene diamine, but all of the examples illustrating the invention are of copolymers of terephthalic acid, isophthalic acid and hexamethylene diamine. Polymers having melting points of above 300.degree. C. were stated to have poor moldability.
it has now been found that copolymers of terephthalic acid, optionally including isophthalic acid, and mixtures of hexamethylene diamine and 2-methyl pentamethylene diamine, in which copolymers the amount of isophthalic acid is less than 40%, and having melting points above 280.degree. C. may be formed and that such polyamides are capable of being melt processed.
Accordingly, the present invention provides a partially crystalline copolyamide formed from aromatic carboxylic acid and aliphatic diamine, said aromatic carboxylic acid being selected from the group consisting of terephthalic acid and mixtures of terephthalic acid and isophthalic acid in which mixtures the amount of isophthalic acid is less that 40%, molar basis, of the mixture, and said aliphatic diamine is a mixture of hexamethylene diamine and 2-methyl pentamethylene diamine, said aliphatic diamine containing at least 40%, molar basis, of hexamethylene diamine, said copolyamide having a melting point in the range of from 280.degree. to 330.degree. C.
In a preferred embodiment of the copolyamide of the invention, the amount of isophthalic acid plus 2-methyl pentamethylene diamine is 15-35%, molar basis, of the total amount of aromatic carboxylic acid and aliphatic diamine.
In a further embodiment, the carboxylic acid is terephthalic acid.
In yet another embodiment, the heat of fusion of the copolyamide is greater than 17 Joules/g. Hereinafter, the word "Joules" is abbreviated "J".
The present invention also provides a process for the preparation of a copolyamide comprising the steps of: aromatic carboxylic acid and aliphatic diamine, said aromatic carboxylic acid being selected from the group consisting of terephthalic acid and mixtures of terephthalic acid and isophthalic acid in which mixtures the amount of isophthalic acid is less that 40%, molar basis, of the mixture, and said ali
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Mok Steven L.
Pagilagan Rolando U.
Du Pont Canada Inc.
E. I. Du Pont de Nemours and Company
Hampton-Highhtower P.
Kight III John
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