Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From carboxylic acid or derivative thereof
Patent
1993-05-19
1995-06-06
Kight, III, John
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From carboxylic acid or derivative thereof
528321, 528324, 528331, 528337, 528338, 528339, 528340, 528347, 428394, 428395, 525432, C08G 6926, C08G 7310
Patent
active
054224209
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to polyamides and more particularly to terpolyamides and multipolyamides having a major proportion of hexamethyleneadipamide units and minor proportions of at least two other amide units, one of these other amide units being those of 2-methylpentamethylenediamine. It also relates to products, particularly fiber products, formed from such ter- and multipolyamides.
BACKGROUND OF THE INVENTION
Poly(hexamethyleneadipamide), commonly known as nylon 6,6, is used in various forms to manufacture a wide variety of useful products. In particular, nylon 6,6 can be spun into fibers for use in many different applications, including carpets, rugs, upholstery, apparel, sewing-thread, and heavy-duty industrial fabrics, to name but a few. There are, however, several disadvantages associated with making and using nylon 6,6 polymer and fibers, particularly as compared to the other common polyamide, poly(.epsilon.-caproamide) or nylon 6. Among these are the lower dye rate of nylon 6,6 and its tendency to develop spherulites which make both the polymer and the fiber cloudy rather than clear. In addition, nylon 6,6 is thermally unstable at normal processing temperatures. When kept in the molten state at processing temperatures for a long time, the polymer forms branched or crosslinked, insoluble, nonfusible gel. The formation of gel in the polymer product and on the walls of processing equipment can result in deficient product with poor processability, particularly when fiber spinning is involved. The fiber spinning breaks which may occur due to gel formation are troublesome and make the winding of large packages impractical.
Various approaches to overcoming each of these disadvantages have been identified. U.S. Pat. No. 4,559,196, for example, provides for room-temperature dyeability by steam-setting a random copolymer of nylon 6,6 and nylon 6 wherein the nylon 6 constitutes 6-12% of the copolymer. U.S. Pat. No. 4,919,874 discloses a nylon 6,6/6 copolymer fiber having reduced spherulites made by polymerizing nylon 6,6 salt with 1-6% -caprolactam and up to 2% of an inorganic calcium salt. U.S. Pat. No. 3,872,055 reports polyamide compositions having decreased gel-formation wherein the polyamides are copolyamides of the diamine-dicarboxylic acid type containing phosphinic and phosphonous acid compounds together with an alkali metal compound.
Modified nylon 6,6 polymers having a combination of properties which minimize or eliminate such disadvantages would be highly desirable.
SUMMARY OF THE INVENTION
In accordance with the invention, there is provided a polyamide comprising between about 80 and about 99 mole percent hexamethyleneadipamide units and between about 0.5 and about 10 mole percent each of at least two other amide units, one of said other units being units of 2-methylpentamethylenediamine (hereinafter sometimes referred to as "Me5").
In a preferred form of the invention, the polyamide comprises between about 90 and about 99 mole percent hexamethyleneadipamide units and between about 0.5 and about 5 mole percent of both the Me5 units and each of the other amide units. The amide units other than those of Me5 are preferably selected from the group consisting of amide units of isophthalic acid, terephthalic acid, 5-sulfoisophthalic acid and salts thereof, dodecanedioic acid, m-xylenediamine, and .epsilon.-caprolactam.
In flake form, the polyamides of this invention typically have relative viscosity (RV) values between about 15 and 45 and melting points ranging from about 215.degree. C. to levels just below 257.degree. C., the melting point of nylon 6,6 homopolymer. When made in a continuous polymerization process, polymer RV can increase to about 80, and when spun into fibers RV will range from about 40 to about 90, with the range of 60 to 80 being most preferred.
As will be described in more detail hereinafter, the ter- and multipolyamides of the invention exhibit reduced spherulite levels and consequently greater optical clarity as compared to both nylon 6,6 hom
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E. I. Du Pont de Nemours and Company
Hampton-Hightower P.
Kight III John
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