There has been a lot of discussion about the right amount of low-melt binder fiber(% by weight) to blend into heat-bonded, polyester fiberfill for quilted, machine washable comforters, with numbers ranging as low as 5% and as high as 20%. Low-melt binder fiber holds the other fibers together, providing structural integrity to the fiberfill used to fill the comforter and, in concert with the comforter construction, contributes to the overall durability of the finished comforter itself. Therefore, it only makes sense to discuss the right amount of low-melt binder fiber in overall context of desired attributes of the finished comforter.
Fiberfill must balance the aesthetic desires for high loft and a soft texture with the practical requirements for resilience and durability, all at a reasonable cost. Low-melt binder fiber provides the required resilience and durability to the fiberfill, preventing it from balling up and/or leaving voids in the comforter during and after machine washing. At the same time low-melt is the costliest component in the fiber blend and too much low-melt tends to make the resulting fiberfill stiff, giving it a slightly crunchy feel and reducing the comforter™ drape. So our goal is to produce a soft and lofty fiberfill that is still durable and resilient, all at the lowest possible cost.
CDS Ensembles Experience
CDS Ensembles has manufactured its own high-loft, thermally bonded fiberfill for comforters for over twenty years. In that time we have determined that 12% (by weight) low melt binder fiber is the minimum required to insure that our comforters meet the customer’s durability requirements. And for many years, 12% was the standard used by CDS for most of its comforters.
But over the years, comforter stitching i.e., quilting patterns, have changed, migrating away from continuous channel and scroll patterns to more sparsely populated jump-tack stitching. This has radically reduced the number of stitches holding the fiber in place and the comforter together from about 4700 stitches to about 330 stitches. That’s 15 times less stitches/square-inch for the jump-tack. This means that, especially during machine washing and drying, the fiberfill has to work harder to maintain it’s shape and structural integrity inside a soaking wet, agitating jump-tack comforter than the same fiberfill in a channel-stitch or diamond-stitch comforter. This is further exacerbated by the trend towards loftier, heavier fiberfill. For these reasons, CDS has found that for most of the styles it is running today, 16% to 18% low melt augment the structural integrity that was lost by the reduction in stitching.
A Channel Quilting Pattern (left) has 15 times more stitches-per-square-inch than a Tack Quilting Pattern(right). Therefore the Tack Quilting Pattern requires a stronger, stiffer fiberfill to compensate for the reduction in stitches used to hold the fiber in place.
Below are other sources of information, available online, with recommendations for the percentage of low melt binder fiber to use in various applications. I would be glad to discuss this further at your convenience.
The original and subsequent patents for card-processed, thermally bonded fiber state. The low melt binder fibers comprise 10 to 30 wt. % of the nonwoven batt and the synthetic and/or natural fibers comprise about 70 to 90 wt.
Technical Bulletin 350904, a fact sheet on thermally bonded polyester fiberfill states that, 25% low melt binder fiber is recommended to blend with regular PLA3 fibers depending on tensile strength and thickness requirements. In general, 18% is commonly used to provide adequate strength for subsequent finishing process and end use durability.4
1 Method of making high loft nonwoven, Patent 7409748, http://www.patents.com/us-7409748.html
2 4281042 Polyester fiberfill blends, http://www.patentgenius.com/patent/4281042.html
3 I realize this paper deals with emerging PLA fibers, as opposed to the PET fibers, but the application and binder fiber requirements are completely applicable.