Textiles: manufacturing – Thread finishing – Surface modification of running length
Reexamination Certificate
1999-10-12
2001-03-13
Vanatta, Amy B. (Department: 3741)
Textiles: manufacturing
Thread finishing
Surface modification of running length
C028S271000, C028S281000
Reexamination Certificate
active
06199250
ABSTRACT:
DESCRIPTION
The present invention regards a method and corresponding equipment for the preparation of multi-filament yarns made of thermoplastic material, bulk-texturized and interlaced, wound individually on reels or in the form of a set of parallel yarns (warp chain) wound on a warp beam, starting from completely or partially stretched thermoplastic yarns with medium or high shrinkage, according to which the bulk-texturizing and interlacing are carried out simultaneously during the phase of hot-shrinkage of the yarn. The yarns obtained using the method described in the present invention can be used both as warp yarns and as weft yarns, as well as yarns for knitting machines in the manufacture of textile articles.
REFERENCES TO PRIOR ART
There are basically three main processes known for obtaining bulk-texturized multi-filament yarns, namely:
1. Texturizing (False Twist)
The yarn is bulk-texturized using the false twist (texturizing) system.
Bulk-texturizing may be carried out at the same time as the stretching when the process is carried out on partially oriented yarn (POY), or else is carried out starting from completely stretched yarn which in all cases undergoes twisting, heating, and untwisting.
This treatment causes a deformation of the filaments with a consequent bulk-texturizing of the yarn. With this system, the filaments are parallel to one another and need to undergo knotting (interlacing) to facilitate the subsequent textile operations of weaving, warping, etc.
This operation is normally carried out with compressed-air interlacing devices. The process is performed on machines called stretching-texturizing machines, which are very costly and complicated. The yarn thus obtained is then warped to achieve the beam for weaving or rectilinear knitting.
2. Air Bulk-Texturizing (Using Compressed-Air Nozzles)
The yarn is bulk-textured using various systems of compressed-air nozzles. Bulk-texturizing is achieved cold by means of powerful jets of air which distort the individual filaments, creating many loops and knots which swell out the yarn.
This process is very costly in terms of consumption of power. It is carried out on machines called air-texturizers, which are very costly, consume a lot and have low productivity.
Furthermore, air with relatively high pressure is required.
The yarn obtained using this process is not very heat-stable since it is subject to considerable shrinking in hot water. The yarn thus obtained is then warped to achieve the beam for weaving or rectilinear knitting.
3. Crimping (Compression in Crimping Chambers)
The yarn is bulk-texturized by means of creases obtained on the filaments of the yarn via mechanical compression with hot air or steam in a metal tube.
After compression and creasing of the filaments, the yarn is stretched out of the chambers, air-interlaced and wound on reels turning at different speeds.
This process is very costly and may be applied only to yarns of medium and large yarn count.
For low-yarn count textile yarns this process has not yet been developed.
PROCESS ACCORDING TO THE INVENTION
The starting yarn which is to undergo the interlacing and simultaneous bulk-texturizing process according to the invention is of the continuous multi-filament type, consisting of substantially stretched thermoplastic material, which is subjected to a considerable hot shrinkage (comprised between 9% and 45%). Excellent results are obtained with a shrinkage of the yarn comprised between 15% and 35%. The percentage values reported here and in the following are relevant to the shrinkage in boiling water.
With the term “substantially stretched” it is meant that the yarn has a residual stretching which in general can be comprised between 25% and 60% and, in the case of polyamidic material, between 25% and 50%.
As starting material it is convenient to use partially oriented yarn (POY) coming directly from spinning and wound on bobbins.
In this latter case, the process involves an initial phase in which the yarn is further and substantially stretched with low-temperature steam heating. The use of steam in this stretching phase is advantageous because the yarn obtained presents a high residual shrinkage.
REFERENCES:
patent: 4644622 (1987-02-01), Bauer et al.
patent: 4667380 (1987-05-01), Symon
patent: 5715584 (1998-02-01), Coons, III et al.
patent: 5950290 (1999-09-01), Sear
Patent Abstracts of Japan, vol. 011, No. 326, Oct. 23, 1987.
G.I.B.A. S.p.A.
Hedman & Costigan ,P.C.
Vanatta Amy B.
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