Gains in Durable Fiberbill Technology

Gains in Durable Fiberfill Technology

By Dr. Thomas W. Theyson

Fiberfill technology has been generally based on polyester staple fibers where the surface is chemically modified to eliminate the normal slip-stick behavior and provide a low coefficient of friction. This provides a modified fiber that has good compression-recovery behavior. When these fibers were originally developed, they found a number of immediate markets, replacing natural materials in applications ranging from pillows to furniture filling fiber.

The market really emerged in the late 1970s with the development by DuPont of a new class of functional topical treatments. The technology DuPont developed was silicone based and designed to further react on the fiber surface during the heat setting process. This resulted in the generation of a slick surface with some wash durability and represented the cutting edge of fiberfill technology at the time.

By the mid-1980’s, it became clear that higher levels of slickness and durability were possible and a second generation of products emerged, based on modified curing technology and amino silicone based components.

Third Generation Technology

This class of products has dominated the fiberfill market for the last 15 years, but now there is market demand for a third generation of products in this area. The issues driving this change include:

The need to support higher processing speeds.
The desire to minimize equipment deposit issues.
The desire to maximize wash and carding durability of the coating.
The desire to reduce cure time/temperature requirements.
The desire to improve slick hand performance.

Goulston Technologies has been working in this area for several years and has successfully pioneered the development of several new chemicals and screening technologies that have resulted in the development of a third generation of products for the fiberfill area. We have developed a basic understanding of the surface chemistry that is involved in this process and have creatively modified the current technology to provide improvements in each of the above areas.

The key to improvement in fiber slickness is understanding and controlling the chemistry of the silicone surface film. This is complicated by the fact the surface chemistry that is carried out in the heat-set oven cannot be duplicated by simplistic bulk material tests in the laboratory. Thus, to investigate the chemical process and finial characteristics of this surface film requires the development of a series of direct and indirect tests to probe the surface.

These tests are used to quantify such properties as degree of polymerization, quantitation of cross-link density and chemistry of polyester surface – silicone polymer interactions. It is these tools that have allowed us to push this technology forward to develop its full potential and, at the same time, look for an innovative approach that will support the future development of improved materials.

Critical Issues

The critical issues addressed in the development of the “third generation” materials are:

Minimizing the stickiness of the surface (Table 1).
Controlling the flexibility of the generated silicone polymers (Table 2).
Enhancing the reactive chemistry of the system.

Table 1 – Control of Stickiness in Silicone Fiberfill Finishes
Finish Technology	Stickiness Rating (1)	Percent Extractable	Viscosity of Extract, cps
1st Generation	7 to 8	70 to 80	~200 M
2nd Generation	4 to 5	40 to 50	~1.5 MM
3rd Generation	1 to 2	20	~2.5 MM

High numbers are sticky, low numbers are dry.

Table 2 – Control of Cross-Link Density to Minimize Deposits
Cross-Link Density	Film Composition	Carding Durability	Wash Durability (Slickness)
Low	Sticky, Soft	Moderate	Moderate
Moderate	Soft, Flexible	Good	Good
High	Hard, Brittle	Poor	Good

This has been accomplished through the detailed optimization of the thin-film silicone reaction chemistry, with special attention paid to controlling the reaction kinetics and the degree of cross-linking in the finial silicone polymer. This results in the following improvements:

High-speed processing: Lowering the tack of the silicone finish improves the high-speed carding and air handling performance.

Deposit issues: Lowering the tack of the finish reduces the build-up of deposits on processing equipment. The control of the level of cross-linking is critical to controlling both sticky deposits (excessive tack) and dry deposits (over cross-linking makes the silicone coating brittle).

Faster curing requirements: Improved coupling agents and selective use of catalyzing agents can provide for a reduction in curing temperature and curing time requirements.

Slickness improvements: Slickness is controlled by balancing the structure and composition of the silicone components. While third generation products represent only a modest improvement in slickness versus second generation products, further improvements in slickness can also be obtained by improving the finish uniformity through optimum application techniques, as well as improvements in fiber design, i.e., cross-section and crimp.

These improvements will result in a new generation of fiberfill finishes that will support the future growth of this expanding market. At the same time, the screening techniques that have been developed will support the further improvement of this technology as we move into the future.