Bleaching and dyeing; fluid treatment and chemical modification – Multiple chemically diverse fibers or fibers with different... – Polyacrylonitrile fiber
Reexamination Certificate
2001-09-14
2004-02-24
Einsmann, Margaret (Department: 1751)
Bleaching and dyeing; fluid treatment and chemical modification
Multiple chemically diverse fibers or fibers with different...
Polyacrylonitrile fiber
C008S594000, C008S115560, C008S927000, C008S930000, C008S934000
Reexamination Certificate
active
06695889
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a pre-dyeing treatment process and a dyeing process for textile products comprising highly crosslinked polyacrylic fibers. This invention also relates to a pretreated and undyed textile product and a dyed textile product obtained by these processes.
2. Prior Art
Recently, a number of functional goods with cleanliness and comfortability have been developed. Among them, particular attention is paid to a textile product in which highly crosslinked polyacrylic fibers are blended to impart antibacterial and deodorizing properties (e.g. U.S. Pat. Nos. 5,853,879 and 5,292,822).
The highly crosslinked polyacrylic fiber has a peculiar chemical structure including a carboxylate. Since this chemical structure can provide a pH buffering capacity and such functions as antibacterial and deodorizing properties, a textile product containing this type of fibers is expected to serve in a broader applications. At the same time, however, the pH control capacity renders dyeing of such textile products extremely difficult. Therefore, these textile products have been dyed in the following manners.
(1) Acid or alkali is added, in advance, to a dye solution in a sufficient amount to block the pH buffering capacity of the highly crosslinked polyacrylic fiber. Then, an item to be dyed is immersed into the acid- or alkali-added dye solution and dyed therein.
(2) Acid or alkali is appropriately added in portions to a dye solution, simultaneously with the dyeing treatment of a textile product comprising highly crosslinked polyacrylic fibers. While the acid or alkali suppresses the pH buffering capacity of the highly crosslinked polyacrylic fibers, other fibers blended in the textile product can be dyed.
In the process (1), the amount of acid or alkali should be adjusted every time the dyeing condition is altered (e.g. type of blended fibers, blending ratio, type of dyes, dye concentration, bath ratio). Eventually, dye solutions are unstable and cause dyeing spots. The hue of the resultant products is unstable, poorly reproducible, and widely different from one dyeing lot to the other.
The pH buffering capacity of the highly crosslinked polyacrylic fiber is variable depending on the type of fibers to be blended with the highly crosslinked polyacrylic fiber. Hence, in the process (2), it is complicated to add acid or alkali properly in portions and thus difficult to control the pH. Similarly, the process (2) results in dyeing spots and apparent hue unevenness, thus being unsuitable for commercial production.
SUMMARY OF THE INVENTION
As described above, it is extremely difficult to dye a textile product which comprises highly crosslinked polyacrylic fibers. Bearing this issue in mind, the present inventors have made intensive researches to find a dyeing process which can simply and constantly provide a desired dyed product, and finally reached the present invention.
The present invention provides a pre-dyeing treatment process for textile products, such as yarns, woven fabrics and knit fabrics, comprising highly crosslinked polyacrylic fibers. This process comprises a pretreatment step of immersing the textile product into an acidic solution and treating the textile product at a high temperature and an elevated pressure. The pretreatment step is conducted at a high temperature ranging from 105 to 140° C. and an elevated pressure ranging from 1.5 to 2 atm. The pre-dyeing treatment process may further comprise the step of washing the pretreated textile product with water, and the step of drying the washed textile product.
A pretreated and undyed textile product of the present invention is obtained by the pre-dyeing treatment process as mentioned above.
The present invention also provides a dyeing process for textile products comprising highly crosslinked polyacrylic fibers. This dyeing process comprises the steps of conducting the above-mentioned pre-dyeing treatment process and thereafter conventionally dyeing fibers blended with the highly crosslinked polyacrylic fibers.
A dyed textile product of the present invention is obtained by the above dyeing process.
According to the present invention, the pH buffering capacity of the highly crosslinked polyacrylic fibers is restrained during the dyeing treatment. In the meantime, the fibers blended with the highly crosslinked polyacrylic fibers can be dyed in a stable hue. It should be noted that the highly crosslinked polyacrylic fibers have their pH buffering capacity restrained temporarily, that is, only during the dyeing treatment. After the dyeing treatment, the restrained pH buffering capacity recovers in time for the final treatment of the textile product. As a result, the finished textile product is a high-quality product dyed in a stable hue, and exhibits the properties deriving from the highly crosslinked polyacrylic fibers such as moisture absorbency, antibacterial property and deodorizing property. With the high functionality and excellent design freedom, the textile product can be utilized widely in clothing applications.
The present invention is hereinafter described in detail.
The textile products as termed in this invention include yarns, yarn combination, textiles of yarn combination, knit fabrics and nonwoven cloth in any of which highly crosslinked polyacrylic fibers are mix-spun or blended with one or more types of fibers selected from synthetic fibers such as polyester fibers, polyamide fibers and polyacrylic fibers; regenerated cellulosic fibers including wet cellulosic fibers (e.g. rayon, cupro and polynosic fibers) and dry cellulosic fibers (e.g. Tencel, Lyocell); cotton, hemp, wool, silk, etc.
These textile products are utilized in underwear, socks, gloves, muffler and the like, and also in sportswear, men's clothes, nightwear- and bedding-related products (e.g. pajamas, futon covers, bedcovers, towels, sheets, pillow covers), curtains, seat covers, car seat covers, cushion covers, architectural decoration-related products, shoe insoles, shoe linings, etc.
In the context of the present invention, the highly crosslinked polyacrylic fiber indicates a fiber prepared from an acrylic fiber by partially hydrolyzing its nitrile group to generate an amido group and a carboxylic acid group, which in turn are partially crosslinked with hydrazines or the like. After the crosslinking treatment with hydrazines, the nitrogen content normally increases by 1.0 to 10.0% by weight. The carboxylic acid group is introduced in an amount of 1.0 to 5.0 mmol/g, whereas an amido group is introduced into the remaining portion. This fiber has a pH buffering capacity to keep the pH constantly between 7.5 and 8.0, and also possesses moisture absorbency, antibacterial property, deodorizing property and the like.
The pretreatment step comprises the steps of preparing a treatment solution for the highly crosslinked polyacrylic fiber in an acid concentration of 0.02 to 0.06 mol/l, immersing a textile product into the treatment solution, and treating the textile product in the treatment solution at 105 to 140° C. under 1.5 to 2 atm for a period of 10 to 80 minutes.
In this pretreatment step, acids for the treatment solution include common inorganic acids and organic acids, preferably organic acids with a high buffering capacity. Typical examples of the organic acids are acetic acid, citric acid, malic acid, etc. In particular, acetic acid is desirable in terms of cost and workability.
The acid concentration of the pretreatment solution is in the range of 0.02 to 0.06 mol/l. At a concentration lower than 0.02 mol/l, Na ions in the terminal carboxyl group cannot be sufficiently substituted with hydrogen. On the contrary, when the concentration exceeds 0.06 mol/l, the effect does not improve any further.
During the pretreatment step, the temperature of the treatment solution is adjusted between 105 to 140° C., preferably between 135 to 140° C. When the temperature is lower than 105° C., Na ions in the terminal carboxyl group of the highly crosslinked polyacrylic fiber cannot be sufficien
Ogino Takeshi
Sakamoto Takamasa
Shiotani Tsutomu
Einsmann Margaret
Heller Ehrman White and McAuliffe
Sakaren Co., Ltd.
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