Stock material or miscellaneous articles – Coated or structually defined flake – particle – cell – strand,... – Rod – strand – filament or fiber
Reexamination Certificate
2001-02-20
2002-04-23
Edwards, Newton (Department: 1774)
Stock material or miscellaneous articles
Coated or structually defined flake, particle, cell, strand,...
Rod, strand, filament or fiber
C428S372000, C428S373000, C428S394000, C264S205000, C264S176100
Reexamination Certificate
active
06376071
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to polyurethane-based fibers and, more particularly, to spandex containing poly(vinylidene fluoride) for improved heat-settability and chemical resistance.
2. Discussion of Related Art
Spandex is widely used in apparel such as hosiery, foundation garments, sportswear.
Japanese Patent Application Publication JP07-082608 discloses poly(tetrafluoroethylene) (“PTFE”) as a compounding agent in polyurethane ureas prepared from a mixture of MDI and 2,4′-MDI. However, the elongation and tenacity of the spandex suffer as a result.
U.S. Pat. No. 3,751,520 discloses that the blending of poly(vinylidene fluoride) (“PVDF”) into thermoplastic polyurethane reduces the coefficient of friction of molded polyurethane parts.
Japanese Patent JP63-060156 discloses the application of mixtures of PVDF and polyurethane to fabrics to form phase-separated coatings.
According to Japanese Published Patent Application 55-084413, PVDF fibers have been melt-spun with the aid of a polyurethane plasticizer which is extracted after spinning. However, the use of PVDF to improve the properties of spandex has not been disclosed.
Reducing the pressure a wearer may feel from a garment containing spandex is generally accomplished by heat-setting the fabric or garment. In order to speed the heat-setting process and save energy, various methods have been used to improve the heat-set efficiency of the spandex. These include altering the composition of the spandex by using selected chain extenders as disclosed in U.S. Pat. No. 4,973,647, and adding certain compounds to the spandex, as disclosed in U.S. Pat. No. 5,539,037. However, improved resistance to perspiration and heat-set efficiency are still needed for spandex.
SUMMARY OF THE INVENTION
The composition of this invention is a polyurethane-based fiber containing 0.1-25 percent poly(vinylidene fluoride), based on the total weight of polyurethane and PVDF in the fiber.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
As used herein, spandex has its customary meaning, that is, a manufactured fiber in which the fiber-forming substance is a long chain synthetic elastomer comprised of at least 85% by weight of a segmented polyurethane. It has now been discovered that both the resistance to perspiration and heat-set efficiency of polyurethane fibers, generally, and spandex, specifically, are unexpectedly and remarkably improved by adding PVDF into the spandex. It is wholly unexpected that two unrelated characteristics can be improved by a single additive, as is the case here.
In addition, tenacity-at-break, permanent set (which can also be helpful in reducing the pressure experienced by the wearer) and elongation-at-break are also increased. Furthermore, addition of PVDF into the spandex did not result in any observed fibrillation of the inventive fiber, nor was the clarity of the fiber affected. This suggests that little or no phase separation of the polymers occurs.
For the sake of convenience, the invention herein will be discussed in terms of spandex. PVDF is used in the spandex and process of the present invention at levels in the range of 0.1-25 percent by weight of total polymers, that is polyurethane and PVDF. Preferred levels of PVDF are 0.3-15 percent, based on the weight of total polymers in the spandex, with 1-15 weight percent being more preferred.
PVDF suitable for use in the spandex of the present invention is substantially linear, has a number average molecular weight of 300-300,000 as measured by gel permeation chromatography using a polystyrene standard, and has a melt viscosity of 5,000-50,000 poise as measured at a shear rate of 50 sec
−1
at 240° C. Although PVDF made by either suspension or emulsion polymerization can be used in the present invention, suspension-polymerized PVDF is preferred, because it can form better solutions, with less gel.
The spandex of this invention can be made from a polyurethaneurea derived from a polymeric glycol, a diisocyanate, and at least one diamine and/or at least one aminoalcohol, or from a polyurethane derived from a polymeric glycol, a diisocyanate, and at least one diol.
Polyether glycols, polyester glycols, and polycarbonate glycols are useful in the present invention. Useful polyether glycols include poly(tetramethyleneether glycol (“PO4G”), poly(tetramethyleneether-co-3-methyl-tetramethyleneether) glycol, and poly(tetramethyleneether-co-2,3-dimethyl-tetramethyleneether) glycol. Useful polyester glycols include poly-&egr;-caprolactone diol and hydroxy-terminated reaction products of diols such as ethylene glycol, 1,3-propane diol, 1,4-butane diol, 1,6-hexane diol, 2,2-dimethyl-1,3-propane diol, 3-methyl-1,5-pentane diol, and mixtures thereof with dicarboxylic acids such as adipic acid, 1,9-nonanedioic acid, and 1,12-dodecanedioic acid. Useful polycarbonate glycols include poly(pentane-1,5-carbonate) diol and poly(hexane-1,6-carbonate) diol. Such glycols have a molecular weight of about 1000-6000, preferably 1500-4500.
Diisocyanates useful in the spandex of the invention include 4-methyl-1,3-phenylene diisocyanate, 1,1′-methylenebis(4-isocyanatobenzene) (“MDI”), 1,4-di-isocyanatobenzene, 1,3-diisocyanatoxylene, 1,4-diisocyanatoxylene, 2,6-napthalene diisocyanate, 5-isocyanato-1-(isocyanatomethyl)-1,3,3-trimethylcyclohexane, 1,1′-methylenebis(4-isocyanatocyclohexane), 2,4-diisocyanato-1-methylcyclohexane, 2,6-diisocyanato-1-methylcyclohexane, 1,4-diisocyanatocyclohexane, and mixtures thereof. 1,1′-Methylenebis(4-isocyanatobenzene) is preferred.
Depending on whether a polyurethane or a polyurethaneurea is to be made, the chain extender can be a low molecular weight diamine, aminoalcohol, diol, or mixtures thereof. When diamine(s) or aminoalcohol(s) are used, polyurethaneureas are formed. When diol(s) are used, polyurethanes are formed. Useful diamines include ethylene diamine (“EDA”), 1,2-propane diamine, 1,3-propane diamine, 1,6-hexamethylene diamine, 1,3-xylylenediamine, N-methylbis(3-aminopropyl)amine, 1,4-cyclohexanediamine, 1,3-cyclohexanediamine (“HMPD”), 2-methyl-1,5-pentanediamine, 1,3-pentanediamine, and mixtures thereof. Ethylene diamine, 1,2-propane diamine, 2-methyl-1,5-pentanediamine, 1,3-cyclo-hexanediamine, 1,3-pentanediamine, and mixtures thereof are preferred. Suitable low molecular weight diols include ethylene glycol (“2G”), 1,3-propane diol, 1,2-propane diol, 2,2-dimethyl-1,3-propane diol, 1,4-butane diol, 3-methyl-1,5-pentane diol, 1,6-hexane diol, 1,4-bis(&bgr;-hydroxyethoxy)benzene, N-methylbis(2-hydroxypropyl)amine, and mixtures thereof. Ethylene glycol, 1,3-propane diol, and 1,4-butanediol are preferred.
So long as the advantages of the present invention are not diminished, small amounts of ingredients of greater than difunctionality can be used, such as diethylenetriamine.
The polyurethane used in making the spandex has a number average molecular weight of 40,000-150,000 as measured by gel permeation chromatography using a polystyrene standard, and a high-temperature-side melting point of 200°-260° C. as measured on a second cycle by differential scanning calorimetry. In order to control the molecular weight of the polyurethane, small amounts of a monofunctional chain terminator such as diethylamine can be added.
The spandex can contain additives such as stabilizers and pigments, provided such additives do not detract from the benefits of the invention. Among such additives are benzotriazole based stabilizers, ultraviolet light absorbers, other light resistance agents, antioxidants, anti-tack agents, lubricants such as mineral oil and silicone oils, antistatic agents. Other examples of additives include hindered phenolic stabilizers such as 2,6-di-t-butyl-4-methyl-phenol as a light stabilizer, antioxidants such as “Sumilizer” GA-80 (Sumitomo Kagaku Kogyo KK), benzotriazoles including a variety of “Tinuvin” stabilizers (Ciba Specialties), phosphorus chemicals such as “Sumilizer” P-16 (Sumitomo), nitrogen oxide traps such as HN-150 (Nippon Hydrazine), light stabilizers such as “Su
Hara Masahi
Tanaka Toshihiro
Umezawa Masao
DuPont-Toray Co. Ltd.
Edwards Newton
LandOfFree
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