Abstract: A method for making an elastic core yarn includes covering an elastic core having a fiber of natural rubber with metric count 200-1000 dtex with a cotton-based covering yarn. The elastic core and the covering yarn are conveyed such that the covering yarn laterally attains a proximity of the elastic core in a wrapping space. The covering yarn is helically wrapped about the elastic core. The conveying speed, and therefore the winding/unwinding speed, is selected such that the elastic core is stretched to a stretching ratio of at least two, and the covering yarn becomes twisted with a final twist direction opposite to its initial twist direction, and forms T coils per length unit of the elastic fiber set between a minimum value T0 and a maximum value T1. An elasticized yarn is thereby obtained, and a fabric, in particular a denim type fabric, is manufactured from this yarn.

Abstract: A method for making an elasticised yarn includes feeding a roving made of a cotton-based natural fibre at a weight percentage of at least 50% and having a linear mass density between 0.1 Nm and 50 Nm, to a stretching unit, and extracting it from the stretching unit at a speed higher than the unwinding speed. The stretched roving and an elastic fibre are jointly pulled through an overlapping unit, forming a spool of the elasticised yarn. The elastic fibre includes a natural rubber containing more than 80% polyisoprene 1,4-cis. The elastic fibre also includes sulphur as a vulcanization agent; a vulcanization accelerator and a vulcanization activator; an anti-tacking agent; an antioxidant agent; and a stabilisation agent. The elastic fibre is obtained by longitudinally cutting a longitudinally cut flat yarn made of the natural rubber, to attain a linear mass density between 50 dtex and 1000 dtex.

Abstract: A method for making an elasticised yarn (9) comprises the steps of feeding a roving (1) made of a cotton-based natural fibre at a weight percentage of at least 50% and having a linear mass density set between 0.1 Nm and 50 Nm, preferably between 0.3 Nm and 25 Nm, to a stretching unit (30), and a step of extracting it from the stretching unit (30) at a speed higher than the unwinding speed; jointly pulling the stretched roving (3) and an elastic fibre (2) through an overlapping unit (40) by a ring spinning unit (50), forming a spool (59) of the elasticised yarn, wherein the elastic fibre (2) comprises a natural rubber containing more than 80% polyisoprene 1,4-cis, along with to sulphur as a vulcanisation agent at a concentration set between 0.5% and 3.

Abstract: A method is disclosed for making an elastic core yarn (50), wherein an elastic core (30) comprising a fibre (10) of natural rubber with metric count 200-1000 dtex is covered by a cotton-based covering yarn (40), comprises a step of conveying the elastic core (30) and the covering yarn (40) in such a way that the covering yarn (40) laterally attains a proximity of the elastic core (30) in a wrapping space (35); a step of helically wrapping the covering yarn (40) about the elastic core (30) in a wrapping space (35), wherein the conveying speed, and therefore the winding/unwinding speed, is selected such that the elastic core (30) is stretched up to a stretching ratio of at least 2, and such that, during this wrapping step, the covering yarn (40) becomes twisted with a final twist direction opposite to its initial twist direction, and forms a number T of coils per length unit of the elastic fibre (10) set between a predetermined minimum value T0 and a predetermined maximum value T1 both depending on the linear m