Bleaching and dyeing; fluid treatment and chemical modification – Chemical modification of textiles or fibers or products thereof – Cellulose fibers
Reexamination Certificate
1998-10-22
2001-03-20
Diamond, Alan (Department: 1753)
Bleaching and dyeing; fluid treatment and chemical modification
Chemical modification of textiles or fibers or products thereof
Cellulose fibers
C008S116400, C008S120000, C008S139000, C008S137000, C008S116100
Reexamination Certificate
active
06203577
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a method for the shrink-proof treatment of a cellulosic fiber textile. More particularly, it relates to a method for treating a cellulosic fiber textile to be fully shrink-proof without a substantial loss of strength so that it may experience minimal shrinkage after washing and minimal hand-and-feel hardening after repetitive washing.
2. Prior Art
Heretofore, cellulosic fiber textiles have been widely used as clothing materials since they have the advantages of moderate moisture absorption, good hand-and-feel textures, and ease of treatment. Such cellulosic fiber textiles, however, suffer from shrinkage after washing and hand-and-feel hardening after repetitive washing.
The cause of the shrinkage after washing is correlated to two phenomena. One phenomenon is the deformation of woven and knitted goods by various forces applied during their manufacture and treatment. More particularly, as washing causes woven and knitted goods to be tossed and turned in a free state without the application of force, they tend to resume their original stable state, inviting shrinkage. Such shrinkage can be prevented by mechanical methods such as is typified by sanforization. The method using a sanforizing machine of the rubber belt or felt blanket type is to impart shrink-proof by physically and continuously compressing the fabric for contraction to reduce the shrinkage potential of the fabric. However, the method cannot achieve a full reduction of the shrinkage potential of thick fabric pieces or hard finished fabrics.
The other phenomenon is the shrinkage of woven and knitted goods as a result of individual fibers absorbing water to swell and to increase their cross-sectional area. This shrinkage occurs upon the absorption of water. After the fabric is dried to remove the water, the fabric tissue cannot recover its original size prior to swelling by itself. The fabric remains shrunk.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a method for treating a cellulosic fiber textile to be fully shrink-proof without a substantial loss of strength so that it may experience minimal shrinkage after washing and minimal hand-and-feel hardening after repetitive washing.
In a first aspect of the present invention, there is provided a method for the shrink-proof treatment of a natural cellulosic fiber textile, comprising the steps of:
treating the fiber textile with liquid ammonia, thereby converting the cellulose I or II crystalline structure in the fiber textile to the cellulose III crystalline structure so that the content of cellulose III crystalline structure in the fiber textile is 10 to 35% based on the entire crystals, and
treating the fiber textile under tension or under no tension with hot water in the following condition of (a) to (e):
(a) at a temperature of 98° C. to less than 105° C. for 1.5 to 5 hours,
(b) at a temperature of 105° C. to less than 115° C. for 1 to 5 hours,
(c) at a temperature of 115° C. to less than 125° C. for 40 minutes to 5 hours,
(d) at a temperature of 125° C. to less than 135° C for 30 minutes to 5 hours, or
(e) at a temperature of 135° C. to 150° C. for 20 minutes to 5 hours,
thereby obtaining a natural cellulosic fiber textile having a minimal shrinkage after washing.
In a second aspect of the present invention, there is provided a method for the shrink-proof treatment of a regenerated cellulosic fiber textile, comprising the steps of:
treating the fiber textile with liquid ammonia thereby converting cellulose II crystalline structure in the fiber textile to the cellulose III crystalline structure, and
treating the fiber textile under tension or under no tension with hot water in the following condition of (a) to (e):
(a) at a temperature of 98° C. to less than 105° C. for 1.5 to 5 hours,
(b) at a temperature of 105° C. to less than 115° C. for 1 to 5 hours,
(c) at a temperature of 115° C. to less than 125° C. for 40 minutes to 5 hours,
(d) at a temperature of 125° C. to less than 135° C. for 30 minutes to 5 hours, or
(e) at a temperature of 135° C. to 150° C. for 20 minutes to 5 hours,
thereby obtaining a regenerated cellulosic fiber textile having a minimal shrinkage after washing.
In the third aspect of the present invention, there is provided a method for the shrink-proof treatment of a cellulosic fiber textile, comprising the steps of:
treating the fiber textile with a liquid ammonia for 5 to 40 seconds, and
treating the fiber textile under tension or under no tension with caustic alkali aqueous in the following condition of (a) or (b):
(a) at a temperature of 90° C. to 150° C. for 1 minute to 5 hours in a caustic alkali concentration of 0.1% by weight to less than 10% by weight, or
(b) at a temperature of −10° C. to less than 90° C. for 20 seconds to 24 hours, in a caustic alkali concentration of 10% by weight to 40% by weight,
thereby obtaining a cellulosic fiber textile having minimal shrinkage after washing.
In the fourth aspect of the present invention, there is provided a method for the shrink-proof treatment of a cellulosic fiber textile, comprising the steps of:
treating the fiber textile with liquid ammonia for 5 to 40 seconds, and
treating the fiber textile under tension or under no tension with a weak alkali aqueous solution having a weak alkali concentration of 0.1% by weight to 15% by weight at a temperature of 90° C. to 150° C. for 10 minutes to 5 hours, thereby obtaining a cellulosic fiber textile having minimal shrinkage after washing.
We have found that by treating a cellulosic fiber textile with liquid ammonia and then treating the fiber textile under tension or under no tension with hot water or an alkali under the specific condition described above, the cellulosic fiber textile can be rendered fully shrink-proof so that it may experience minimal shrinkage after washing and minimal hand-and-feel hardening after repetitive washing. This is accomplished without a substantial loss of strength.
More particularly, when a cellulosic fiber textile is impregnated with liquid ammonia, the liquid ammonia penetrates into not only the amorphous regions, but also the crystalline regions of the cellulose to break down the hydrogen bonds so that the fibers in their entirety are swollen. Thereafter, heat treatment is carried out to evaporate the liquid ammonia whereupon hydrogen bonds are newly formed and a cellulose III crystalline structure is created at least partially in the crystalline region. The crystals are fixed in a swollen state. This results in a lower crystallinity. When such a fabric is given a resin finish the crease and shrink-proof properties are improved with a slight loss of strength. This fact is well known in the art.
In contrast, by treating a cellulosic fiber textile with hot water or an alkali subsequent to liquid ammonia treatment under the specific condition described above, the cellulose III crystalline structure is restored to the cellulose I or II crystalline structure, during which process the swollen state is maintained due to the penetration of hot water or the alkali. Then, the fiber structure is set as swollen and relaxed. As a result, the influence of swelling and tension relaxation by water upon washing is minimized or eliminated. Shrink-proof treatment is accomplished in this way.
Subsequent resin treatment on the thus treated cellulosic fiber textile can impart improved crease or shrink-proof properties without a substantial loss of strength when compared with the prior art resin treatment.
More particularly, the prior art resin treatment of a cellulosic fiber textile has the tendency that as the amount of resin added increases, the crease or shrink-proof properties are improved, but the tensile strength is reduced at the same time. An improvement in the crease or shrink-proof properties is achieved by introducing crosslinks between the cellulosic fibers to stabilize the hydrogen bonds while a lowering of the tensile strength occurs because of the introduction of crosslinks which invite the likelihood of local
Harada Kazuhiko
Hasegawa Osamu
Hirai Takayuki
Iida Hirotaka
Ikeda Kiyoshi
Birch & Stewart Kolasch & Birch, LLP
Diamond Alan
Nisshinbo Industries Inc.
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