Adhesive bonding and miscellaneous chemical manufacture – Methods – Surface bonding and/or assembly therefor
Reexamination Certificate
1999-01-15
2003-06-17
Yao, Sam Chuan (Department: 1733)
Adhesive bonding and miscellaneous chemical manufacture
Methods
Surface bonding and/or assembly therefor
C156S148000, C156S181000, C204S166000, C028S104000
Reexamination Certificate
active
06579391
ABSTRACT:
TECHNICAL FIELD
The present invention relates to hydroentangled (spunlace) nonwoven fabric, and more particularly, the invention relates to an improved method for foam bonding of hydroentangled (spunlace) nonwoven fabric.
RELATED ART
In the 1970s a considerable amount of work was done in the area of latex addition to bond spunlace fabrics. DuPont investigated resin treatment of SONTARA® (100% polyester spunlaced fabric). DuPont developed an apparatus for measuring the resistance to disentanglement of spunlace fabric in 1979. DuPont further discovered one series of spunlace fabrics treated with 30% soft acrylic latex (by padding) which (1) showed no signs of disentanglement after 200 cycles on their instrument and (2) withstood five laundering cycles. The fabrics were subsequently re-tested after laundering and had similar excellent results. DuPont reported that their fabrics had “a crisper hand” as a result of treatment. Burlington Formed Fabrics Division of Burlington Industries, Inc. reported the use of latex in stabilizing their NEXUS® spunlace fabrics. They reported their fabrics to have better pilling resistance and durability, but at the expense of increased stiffness.
In 1986 Chicopee patented a process (see U.S. Pat. No. 4,623,575) to make food service wipes which were made by low specific energy hydroentangling followed by dry print bonding. Normally, in print bonding the fabric is prewetted and then the binder is applied in the wet state. This is then followed by drying. In the case of dry print bonding, the fabric is dried after prewetting and then the binder is applied. The resulting fabric has a good combination of strength, softness and durability. U.S. Pat. No. 5,009,747 issued to The Dexter Corporation in 1991 disclosing the addition of small amounts of latex to polyester/woodpulp hyrdroentangled fabrics. However, none of these patents disclosed the use of foam application as a method of bonding hydroentangled nonwoven fabrics.
U.S. Pat. No. 4,499,139 to The Kendall Company in 1985 discloses the use of latex foam (mixed with clay) to coat a single-ply hydroentangled fabric with a knife-over-roll applicator whereby the foam is worked into the only a portion of the fabric profile so as to leave the back surface free of foam binder. The patent discloses that the material has sufficient hydrophobicity to be a bacterial barrier while preserving comfort, drapeability, air permeability, flexibility and hand.
It is well known that a major drawback of spunlace (hydroentangled) nonwoven fabrics is that they disentangle easily and therefore lack abrasion resistance and have poor recovery from small strains. This is caused by the frictional nature of the hydroentangling process which does not have the locking characteristics of yam-based fabrics. This deficiency can be corrected by entangling the fabrics at high levels of specific energy (energy supplied to the hydroentangling jets) or by saturation bonding the fabrics with chemical binders. Both of these methods have well known disadvantages including that (1) high specific energy entangling increases production and filtration costs and (2) chemical binding at both high and low levels of saturation (dipping the entire nonwoven fabric into a latex bath) tends to make the spunlace nonwoven fabric stiffer and to cause the fabric to lose many of its desirable aesthetic properties such as good hand and drape.
The purpose of applicants' invention is to use a very low level (≦5% by weight) application of foamed acrylic latex binder to fully penetrate spunlaced cotton, acrylic, and/or polyester fabrics in such a manner as to reduce the loss of desirable properties while still improving fabric dimensional stability and abrasion resistance. Further, applicants believe that their novel process will work with a spunlace fabric formed from any staple fiber. Applicants have achieved the desired spunlace fabric characteristics through use of the novel foam binder application process technique described herein.
DISCLOSURE OF THE INVENTION
In accordance with the present invention, applicants provide a method of producing a hydroentangled nonwoven web material with good strength and abrasion resistance while maintaining good fabric aesthetics. The method comprises forming a substrate by carding and cross-lapping fibers wherein the fibers are synthetic and/or natural fibers. The substrate of fibers are then hydroentangled to form a spunlace web, and an effective amount of a foamed adhesive bonding material is then applied to the spunlace web. Next, a force is applied to the spunlace web to cause the foamed material to fully penetrate the spunlace web from front to back.
It is therefore an object of the present invention to provide an improved hydroentangled (spunlace) nonwoven fabric that possesses good strength and abrasion resistance characteristics while maintaining desirable fabric aesthetics such as hand and drape.
It is another object of the present invention to provide a method of treating a hydroentangled (spunlace) nonwoven fabric with a novel foamed acrylic latex binder application that reduces the loss of desirable fabric qualities such as good strength and abrasion resistance while simultaneously maintaining good fabric aesthetics such as hand and drape.
Some of the objects of the invention having been stated hereinabove, other objects will become evident as the description proceeds, when taken in connection with the accompanying drawings as best described hereinbelow.
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Gilmore Kerry L.
Gilmore Thomas F.
Shahani Amit
Shiffler Donald A.
Gilmore Kerry L.
Jenkins & Wilson, P.A.
North Carolina State University
Yao Sam Chuan
LandOfFree
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