Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From carboxylic acid or derivative thereof
Reexamination Certificate
2000-04-06
2001-07-10
Hampton-Hightower, P. (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From carboxylic acid or derivative thereof
C528S312000, C528S313000, C528S322000, C528S332000, C528S336000, C528S337000, C528S480000, C008S530000, C008S531000, C008S582000, C008S629000, C008S650000
Reexamination Certificate
active
06258928
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a process for treating polyamides, such as nylon, to improve a property of the polyamide. The invention also relates to polyamides having improved characteristics, such as improved dyed color depth, dyed color uniformity, hue, elimination of light dyeing ends, protection of dye sites from degradation, protection against ultra-violet (UV) degradation, reduced yellowing or oxidation, and/or resistance to loss of dyeability.
2. Description of Related Art
Polyamides often contain terminal primary amines, which are affected by reactive and/or oxidizing environments found in prolonged storage or in certain preparatory processing applied to polyamides, such as heat setting or molding.
Heat setting is often applied to substrates containing polyamide. Heat setting involves heat exposure for limited times at limited temperatures. Heat setting is useful, for example, to process polyamide fabrics or garments containing spandex fiber. Heat setting is performed to confer dimensional stability and wrinkle resistance to the fabrics or garment.
Often the heat set process results in some oxidation and yellowing of the nylon with loss of dyeability, dyed color uniformity, color depth, and/or hue. Yellowing of the polyamide component is noticeable in the natural or un-dyed state. Yellowing is objectionable in fabrics meant to be white and detracts from the desired color contrast sought in dyed fabric prints on a white fabric background.
Current methods to impart whiteness retention in nylon fabrics include adding stabilizers of the IRGANOX® type from CIBA GEIGY (Basel, Switzerland) or Nylostab Seed® from CLARIANT (Basel, Switzerland). Known whiteness retention and heat stabilizers for nylon include the phosphorus oxy acid type and their salts, as well as, the classes of materials disclosed in U.S. Pat. Nos. 3,839,392 and 3,907,746.
Stabilizers added to nylon polymer often excessively foam the polymer when added to an autoclave polymerization process. Moreover, high stabilizer loadings often produce poor polymer and poor uniformity from batch to batch. Also, loss of the stabilizer additive from nylon yarn and fabrics during aqueous processing steps, especially dyeing, often make the addition of stabilizers undesirable.
There is thus a need to provide polyamides and products, such as fabrics constructed therefrom that retain their dyeability characteristics and whiteness retention, and avoid or reduce disadvantages of current methods.
SUMMARY OF THE INVENTION
In accordance with these needs, there has been provided a process for improving characteristics of a polyamide having X gram equivalents of amine end groups per 1,000 kg of polyamide, comprising contacting prior to dyeing or any treatment that makes at least some of the amine end groups unavailable for dyeing, the polyamide or a salt useful to form the polyamide, with a thiocyanate groups, such that the polyamide after contacting or the polyamide formed from the salt contains Y gram equivalents of thiocyanate groups that protect the amine end groups, such that about 0.001<Y/X<about 1.5.
The present invention also provides a polyamide having improved characteristics, wherein the polyamide contains terminal amine dye sites protected by up to about a stoichiometric amount of thiocyanate groups.
The present invention further provides a composition comprising a polyamide salt solution and a thiocyanate.
Further in accordance with the objectives of the present invention, there is provided a process for improving characteristics of a polyamide, comprising contacting a polyamide having amine end groups with thiocyanate, such that the polyamide after contacting contains up to about a stoichiometric amount of thiocyanate groups based on the amine end groups.
The present invention also provides a process for improving dyeability characteristics of a polyamide, comprising contacting a polyamide prior to dyeing or heat-setting with an amount of thiocyanate effective to protect dye-sites of the polyamide.
The present invention further provides a process for improving dyeability characteristics of a polyamide, comprising contacting a polyamide salt with a thiocyanate, and polymerizing the salt to form a polyamide.
The present invention also provides a process for improving characteristics of a polyamide fiber, yarn, film, tow, fabric, molded article, or garment comprising contacting the fiber, yarn, film, tow, fabric, molded article, carpet, garment, or other article prior to any dyeing or other treatment that makes the amine end groups unavailable for dyeing, with a thiocyanate.
Further objects, features, and advantages of the invention will become apparent from the description that follows.
REFERENCES:
patent: 1398357 (1921-11-01), Briggs et al.
patent: 2869968 (1959-01-01), Thummel et al.
patent: 3577392 (1971-05-01), Kochhar et al.
patent: 3652199 (1972-03-01), Leung
patent: 3839392 (1974-10-01), Follows et al.
patent: 3907746 (1975-09-01), Follows
patent: 549986 (1942-12-01), None
patent: 731005 (1955-06-01), None
patent: 892379 (1962-03-01), None
patent: 1793016 A1 (1993-02-01), None
Richard W. Harold, Richard S. Hunter, Special Scales for White Colors, 1987, p. 140-146, Color Technology in the Textile Industry. (No Month).
Maillincrodt Baker, Inc., Ammonium Thiocyanate, MSDS No. A6276, Eff. Date Dec. 8, 1996, http://www.itbaker.com/msds/a6276.htm, Oct. 13, 1999 pp. 1-7.
Maillincrodt Baker, Inc., Ammonium Thiocyanate, Solution, MSDS No. A6280, Eff. Date Dec. 8, 1996, http://www.itbaker.com/msds/a6280.htm, Oct. 13,1999 pp. 1-7.
Baird Bennett Ray
Lewis David Malcolm
Patel Kamleshkumar Chunilal
E. I. Du Pont de Nemours and Company
Hampton-Hightower P.
LandOfFree
Process for improving characteristics of a polyamide does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Process for improving characteristics of a polyamide, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Process for improving characteristics of a polyamide will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2555557