Stock material or miscellaneous articles – Coated or structually defined flake – particle – cell – strand,... – Rod – strand – filament or fiber
Reexamination Certificate
1999-01-11
2003-03-25
Juska, Cheryl A. (Department: 1771)
Stock material or miscellaneous articles
Coated or structually defined flake, particle, cell, strand,...
Rod, strand, filament or fiber
C428S378000, C428S394000, C252S008810, C252S008840
Reexamination Certificate
active
06537662
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to soil-resistant spin finish compositions, a method for applying the compositions to synthetic fibers, and final fiber constructions made from synthetic fibers treated with the soil-resistant spin finish compositions.
BACKGROUND OF THE INVENTION
Lubrication and finishing of yarns and threads, such as cotton and silk, has been practiced since ancient times. Such yarns and threads, derived from natural-occurring plants and animals such as cotton plants and silkworms, often required lubrication or finishing by “oiling” or “sizing” to facilitate spinning and bundling. Lubricants used were typically natural hydrophobic oils, such as mineral oil or coconut oil. Sometimes, molten waxes such as beeswax were employed which, when cooled, formed a solid lubricating finish. Usually, the fibers were “sized” by applying a lubricant and/or adhesive material to yarn or warp threads in a weaving operation to impart cohesion and lubricity. Historically, sizes have been hard coatings, applied neat and at a higher fiber add-on than spin finishes, and were often based on starch, wax, and other oleophilic materials. For example, U.S. Pat. No. 1,681,745 discloses a beeswax-based size for artificial silk (rayon) which is applied molten and solidifies quickly before the thread is wound up, thus assuring bundle cohesion and lubrication in all subsequent operations.
While sizes were useful in facilitating the spinning and bundling of fibers, their presence in finished articles was found to be undesirable. In particular, the oleophilic nature of the sizes was found to adversely effect the soil resistance of the finished article. Sizes also frequently compromised the appearance and handle of the article Consequently, it became common practice to remove the size from a woven article after its manufacture by scouring the article in hot and/or detergent-containing water. In some instances, these sizes were also removed or reduced to acceptable levels as an inherent part of the dying process, as when the woven article is dyed through immersion in aqueous dye baths. However, this later methodology, in which the scouring and dying steps were effectively combined into a single process, also had its drawbacks. In particular, the presence of sizes in the dye bath frequently had adverse affects on the dying process, while also necessitating frequent replenishment of the dye solution.
After World War II, fibers were introduced which were made from synthetic polymers such as nylon, polyolefin, polyester and acrylic. These new high performance synthetic fibers required the use of special sizes called “spin finishes” during spinning and the subsequent fiber operations (e.g., bundling or sizing) required to produce the final woven article (e.g., fabric or carpet). The spin finish served several functions, including (1) reducing the friction developed as the synthetic fibers passed over metal and ceramic machinery surfaces, (2) imparting fiber-to-fiber lubricity, (3) minimizing electrical static charge buildup (a problem especially pronounced in the manufacture of woven articles from synthetic fibers), and, in some instances, (4) providing cohesion to the fiber. In addition, with proper use of additives, spin finish compositions could be made that were stable to high temperatures and pressures, had a controllable viscosity under application conditions, were non-corrosive, and were relatively safe to both the workers and the environment. (See Pushpa, B. et al., “Spin Finishes,”
Colourage,
Nov. 16-30, 1987 (17-26)). However, as with their sizing predecessors, the spin finishes had to be removed from the articles woven from the fibers, typically by scouring, to minimize soiling problems See, e g., U.S. Pat. No. 5,263,308 (Lee et al.), Col. 2, Lines 23-25.
The process of scouring is very undesirable in that it is a tedious process which adds to manufacturing costs, while also posing water pollution problems and health concerns. See, e.g., U.S. Pat. No. 5,263,308 (Lee et al.), Col. 2, Lines 20-24. Accordingly, some attempts have been made to avoid the need for scouring by treating unscoured carpets with agents that improve the soil resistance, handle, and other characteristics of the unscoured carpet to levels acceptable for the intended end use. Thus, U.S. Pat. No. 5,756,181 (Wang et al.) and U.S. Pat. No. 5,738,687 (Kamrath et al.) describe the treatment of unscoured carpet with certain polycarboxylate salts to achieve desirable soil resistance and repellency characteristics. Similarly, U.S. Ser. No. 08/595,592 (Wang et al.) describes the topical treatment of unscoured carpets with various inorganic agents such as silica to improve the soil resistance of the carpet. However, while these treatments are notable improvements in the art and work quite well in certain end uses, the requirement of a polycarboxylate salt and/or an inorganic additive is not desirable for all applications.
Other methods have been proposed in the art that are aimed at removing soil-attracting fiber finishes while avoiding the need for scouring and, in some cases, the need for additional treatment agents However, most of these methods have proven impractical in a commercial setting. For instance, Japanese Patent 2,572,503 describes a polyether oil spin finish that is sublimed or decomposed from spun-out yarn by heating the treated yarn to 180-220° C. Unfortunately, the high temperatures required for this process have an adverse effect on the yarn, and the sublimation process itself is undesirable because of the energy and pollution problems attendant thereto. Accordingly, it remains the conventional practice in the art to remove spin finishes by scouring.
Most spin finishes currently known to the art are aqueous emulsions or dispersions, although some neat spin finishes are also known. The former are frequently preferred to neat spin finishes because the larger volume of finish applied per fiber weight results in lower application variability. Additionally, the water helps eliminate troublesome static charge, especially when formulated with other additives. (See Postman, W., “Spin Finishes Explained,”
Textile Research Journal,
July 1980 (444-453). Also, aqueous emulsions and dispersions frequently have lower viscosities, and therefore better frictional properties, than neat systems, and are easier to remove by scouring or during the dyeing process. See, e.g., R. J. Crossfield, “Applying Spin Finishes for Optimum Downstream Fiber Quality” (Aug. 18, 1998), and R. J. Crossfield, “Lubricants for Synthetic Fibers” (Jul. 24, 1998), both publications of Goulston Technologies, Inc.
The patent literature describes the use of a wide variety of aqueous emulsions or dispersions as components of various fiber treatments or finishes. These materials are typically removed by scouring with hot water and/or detergent, or by other methods (e.g., as an inherent part of immersion dying) to avoid the detrimental affect of the finish on the soiling properties of the final article of commerce.
U.S. Pat. No. 4,388,372 (Champaneria et al.) describes an improved process for making soil-resistant filaments of a synthetic linear polycarbonamide, preferably 6-nylon and 66-nylon, by applying a water-borne primary spin finish composition comprising a perfluoroalkyl ester, a modified epoxy resin and a non-ionic textile lubricant based on poly(ethylene glycol). Particularly preferred lubricants include n-butyl initiated random copolymers of ethylene/propylene oxide. At Col. 6, Lines 59-61 of the reference, it is noted that “Excessive amounts of textile lubricants in the finish composition can interfere in the durability and effectiveness of the soil-resistant ingredients.” Accordingly, much of the lubricant is removed at a later stage of processing when the filaments are subjected to a scouring or dyeing operation (Col. 6, lines 51-55), and application of a secondary fiber finish composition to the spun yarn is recommended at the point between the take up and windup rolls (Col. 12, lines 18-19).
U.S. Pat. No. 5,139,873 (Rebouillat)
Alm Roger R.
Dunsmore Irvin F.
Franchina Nicole L.
Hauser Edward R.
Jariwala Chetan P.
3M Innovative Properties Company
Juska Cheryl A.
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