How to identify the quality of polyester DTY yarn?
1.Strength and extension
Regarding fiber strength, higher is not always better. For low-elastic yarn, a strength of 2.5cN/dtex and an elongation of 12% to 30% can meet the requirements for weaving and clothing use.
The higher its toughness (strength × elongation/2), the better. Yarns with high toughness not only have good intrinsic quality, but are also wear-resistant and fold-resistant.
In actual production, different weaving methods have different requirements for toughness. For example, weft knitting machines require that the strength of DTY is much lower than that of warp knitting and weaving. The elongation range of weft yarns is wider, but the elongation of warp yarns cannot too high.
In DTY production, the strength and elongation are generally controlled by adjusting the stretching ratio of the filament. As the draw ratio increases, the strength of the filament increases and the elongation decreases. However, when the draw ratio is too large, the strength and elongation of the filament decrease.
2.Crimping performance
Crimp performance includes crimp ratio KE, crimp stability KB and boiling water shrinkage.
With a high shrinkage rate, DTY has a plump feel, beautiful appearance and good elasticity. Curl stability represents the degree of progressive loss of crimp during the weaving and wearing process and is inversely proportional to the crimp ratio. Therefore, these two indicators must be taken into consideration in actual production.
DTY with a higher curl rate can cover up some uneven dyeing, so the curl rate is often controlled to be slightly higher during the production process. However, if DTY is dyed in packages during post-processing, the package will be difficult to unwind after dyeing due to the high boiling water shrinkage of DTY with high shrinkage. If DTY silk is twisted or woven into fabric and then dyed, there is no restriction. At this time, the crimp rate can be controlled higher.
3. Even dyeing
Any DTY with high physical properties such as strength, elongation, crimp rate, evenness unevenness, and fiber structure unevenness will have problems such as horizontal stripes and color differences after being woven into fabrics.
Therefore, the DTY production process must be controlled and detected in time during finished product inspection to prevent DTY with poor dyeing uniformity from being mixed into normal products, resulting in a decline in the quality of a large number of fabrics in the end.
4. Burr
At present, one of the main quality problems of low-elastic yarn is the production of lint. The existence of burrs will affect the smooth progress of the subsequent spinning process and the quality of the fabric.
Different weaving processes have different requirements for burrs. DTY used in machine weaving requires twisting and sizing before weaving, so the requirements for burrs are not strict； For the low-elastic yarn used in water-jet looms, burrs are not expected to appear；In knitting processing, the silk used for weft knitting does not have strict requirements on burrs due to its short weaving process and low speed；The production speed of warp knitting yarn is high, and each yarn must pass through the eye of the needle， The presence of burrs can easily cause breakage and should be strictly controlled.
5.Stiffness and tight spots
Stiff silk refers to the segmented, continuous and unfluffy tightly twisted silk on DTY. Tight spots refer to less severe stiffness, that is, the continuous length of the stiffness is very short and almost in the shape of a point. Stiff threads and tight spots can be identified through visual inspection and appearance grading. Stiff silk can also be identified on dyed stockings. It is darker than normal silk and appears in strips. Tight spots have dark spots on the sock tube, which are generally difficult to identify.
Jinjiang Xinglilai Yarns Co.,Ltd--Sinrylion
Our company has more than 400 sets of different machines，and warping beams and so on,
Provide high-quality polyester dty yarn such as 150d 48f to weaving label factories,
You can contact us for specific product information.