Textiles: manufacturing
Reexamination Certificate
2000-08-08
2003-03-25
Gupta, Yogendra N. (Department: 1751)
Textiles: manufacturing
C252S008820, C252S008830, C252S008840, C252S008850
Reexamination Certificate
active
06536804
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to low melting, high solids spin finish compositions, a method for applying the compositions to fibrous substrates, and fibrous substrates treated with the high solids 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 is 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, which is necessitated by the use of sizes and spin finishes, 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 work quite well for their intended purpose, they require the incorporation of additional steps and materials, thereby increasing the cost and complexity of the manufacturing process. There is thus a need in the art for a method for making carpets and other woven articles that avoids the need for scouring without necessitating the use of additional treatment steps or agents.
A further problem associated with the use of many conventional spin finishes arises during the manufacturing process itself. The vast majority of spin finishes for synthetic fibers are applied from solution or dispersion in water and/or solvent. Health and safety concerns make high solvent levels in the spin finish impractical unless the solvent is non-toxic, non-flammable, and environmentally neutral. As a practical matter, this has limited the solvent selection to water. Also, aqueous dispersions of spin finishes have been 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).
Several examples of aqueous spin finish compositions are known to the art. Thus, U.S. Pat. No. 5,153,046 (Murphy) describes an aqueous finish composition for imparting soil-resistant protection to textile fibers, e.g., nylon yarn, which is stable to the high shear environment of a fiber finish application system. This composition is composed of 1-35% (weight) of nonionic fluorochemical textile anti-soilant, 65-95% of nonionic water-soluble or water-emulsifiable lubricant, and 0.05-15% each of quaternary ammonium or protonated amine surfactant and nonionic surfactant. Preferred lubricants are polyethylene glycol 600 monolaurate and methoxypolyethylene glycol 400 monopelargonate.
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. 4,883,604 (Veitenhansl et al.) describes compositions and methods for smoothing textile fibers and sheet-form textiles made from the fibers. These compositions, which are described as solutions, emulsions, or aqueous dispersions, contain a combination of aliphatic polyether having C
6
-C
24
alkyl radicals and containing 1 to 25 units o
Dunsmore Irvin F.
Hauser Edward R.
Jariwala Chetan P.
Lockridge James R.
Fortkort John
Gupta Yogendra N.
Hamlin Derrick G
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