Understand The Elastic Material Commonly Used In Diapers - Spandex Yarn

The requirement related to elasticity of diapers is to fit the body closely, which is a basic requirement. At present, 90% of the elastic materials used by manufacturers are spandex yarn. This article briefly expounds the properties of spandex fiber and its main problems and solutions during its use.

1. Performance of spandex yarn

At present, spandex yarn is a widely accepted elastic material in the diaper industry, and its performance can be represented by a stress-strain curve. The maximum stretch ratio is above 5.0, and the effective stretch ratio is 2.5~3.5. Different brands of spandex have different stress per unit. After recovery of 20%, the stress tends to be stable, and the stress of different stretch ratios rebounds > 20%. Convergence (rebound force). not related to stretch ratio).

By analyzing the stress-strain curves at different stretching ratios, it can be concluded that the entire curve is relatively close to a linear relationship when stretched at low magnifications, that is, when stretched at low magnifications, the resilience and restoring force are in a linear proportional relationship . At high stretching ratio, the whole curve is parabolic, that is to say, as the stretching ratio increases, the curve gradually changes from a linear relationship to a quadratic function relationship.

At present, China's spandex yarn production capacity accounts for 70% of the world's, and its production threshold is relatively high and the investment is large. More than ten years ago, there were only products imported from abroad, and there was only one. Now there are many manufacturers in China, and the production processes are very similar. Its production is divided into two processes, polymerization and spinning. The degree of polymerization of the polymerization process affects elastic modulus, elongation, recovery and uniformity. The spinning process can affect the spandex winding, shape stability and unwinding process.

2. Main problems and solutions in the use of spandex yarn

During the use of spandex yarn, the two main problems are broken wire and loss of elasticity.

There may be two reasons for broken wires. On the one hand, the quality is abnormal, which can be roughly seen from the appearance. It is mainly caused by adhesion, knots, and splitting caused by process defects. It may also be internal adhesion and roundness caused by improper storage. Shoulder, side slip, etc. On the other hand, there are problems caused by improper use, such as insufficient unwinding tension, large difference in the transmission tension of the guide wheel, etc.

The use of constant tension control can solve the problem of spandex yarn breakage. The advantage of constant tension control is that each spandex yarn can be set to a different tension.

The loss of elasticity is manifested in that the elasticity of the elastic belt of the diaper is significantly different from that of the diaper, and the loss of elasticity is 10% to 40%. The reason for the loss of elasticity involves the material and production process of the relevant materials. The influence of material includes its coefficient of friction, softness of hot melt adhesive, PE film, non-woven fabric, etc. The influence of the production process is mainly on the friction of the roll feeding, the temperature of the glue and the amount of glue used.

Spandex yarn is a kind of high elasticity and high elongation synthetic fiber, which has been widely used in diapers. Understanding the relevant knowledge of spandex fiber is conducive to its further development.