Yarn and fabric with zones of variable heat set character
View Patent ↗Yarns and fabrics formed from such yarns incorporating an arrangement of discrete zones of variable heat treat history thereby imparting differential dye affinity and structural character at discrete zones along the yarn length are described. The differential dye affinity permits variable shading along the yarn length when the yarn is subjected to a dye bath. Processes and equipment for manufacturing such yarns are also provided.
1. A method of applying variable coloration along the length of a yarn, the method comprising the steps of:
(a) providing an elongate polyester partially oriented yarn structure;
(b) selectively applying a heat sink liquid to discrete segments of the elongate yarn structure to provide an arrangement of wet segments interspersed with substantially dry segments along the length of the elongate yarn structure;
(c) delivering the elongate yarn structure having wet segments interspersed with substantially dry segments to a heat treatment unit;
(d) delivering heating energy to the elongate yarn structure at the heat treatment unit such that the temperature within portions of the dry segments is raised to a substantially uniform elevated first temperature across the yarn structure and such that the temperature within portions of the wet segments is raised to a substantially uniform second temperature below the first temperature,
wherein after delivering heating energy to the elongate yarn structure, the dry segments are first segments having a first substantially uniform cross-sectional area and the wet segments are second segments having a second substantially uniform cross-sectional area, wherein the first substantially uniform cross-sectional area and the first segments are characterized by a dye affinity in excess of the second segments is greater than the second substantially uniform cross-sectional area, and wherein the average level of crystalline orientation of first segments as measured by the Herman Orientation Function is at least 5% greater than the average level of crystalline orientation of the second segments; and
(e) subsequent step “d” subjecting the elongate yarn structure to a substantially uniform dye treatment.
2. The method as recited in claim 1 , wherein the elongate yarn structure is in a fabric during step “e”.
3. The method as recited in claim 1 , wherein the heat sink liquid comprises water.
4. The method as recited in claim 2 , wherein the fabric is a pile fabric.
5. The method as recited in claim 2 , wherein the fabric is a warp knit pile fabric.
6. The method as recited in claim 2 , wherein the fabric is a double needle bar warp knit pile fabric.
7. The method as recited in claim 2 , wherein the fabric is a single needle bar warp knit pile fabric.
8. The method as recited in claim 2 , wherein the fabric is a woven fabric.
9. The method as recited in claim 1 , wherein the yarn is a multi-filament polyester partially oriented yarn.