Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – At least one aryl ring which is part of a fused or bridged...
Reexamination Certificate
1999-03-03
2001-04-17
Yoon, Tae (Department: 1714)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
At least one aryl ring which is part of a fused or bridged...
C524S270000, C524S477000, C524S484000, C524S487000, C524S515000
Reexamination Certificate
active
06218457
ABSTRACT:
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
N/A
BACKGROUND OF THE INVENTION
The present invention relates to hot melt adhesive compositions, and more particularly to a polybutylene based hot melt adhesive which finds utility in nonwoven disposable absorbent articles such as diapers.
Numerous types of nonwoven disposable absorbent articles are commercially available, and are manufactured for use in the absorption and containment of bodily waste such as urine and feces. Typical of such articles are disposable diapers for infants, and undergarments for incontinent adults. Hot melt adhesives are typically used in the construction of such disposable articles.
While a wide range of hot melt adhesive compositions are known and used in the construction of disposable articles, it is also well known that a hot melt adhesive used for bonding in a particular use or application may be completely unsuitable for other uses or applications. Thus, various hot melt adhesive compositions are used in the construction of disposable articles. For example, it is well known that polyolefin based hot melt adhesives are suitable for the construction of diapers, particularly in the bonding of polyethylene films, or the like, to tissue or nonwoven substrates in the production of such articles. However, it is also known that polyolefin based hot melt adhesives are not suitable for bonding of the elastic bands in the diapers because the application characteristics, e.g. sprayability, of polyolefin based adhesives is undesirable for such an application. For this reason, hot melt adhesives based on styrenic block copolymers such as styrene-isoprene-styrene (SIS) block copolymers or styrene-butadiene-styrene (SBS) block copolymers are used for elastic attachment applications. These styrenic block copolymer adhesives, however, also possess shortcomings such as viscosity instability which manifests itself at elevated temperature.
More importantly, the shortcomings of conventional SIS and SBS based hot melt adhesives are particularly manifested in nonwoven applications which require seaming, such as the attachment of elastic side panels to diapers, or adhering of functional attachments such as fastening tape to disposable diapers. Oftentimes such components are required to function at body temperature under high peel stress and/or high shear stress for long periods of time. In such instances, the peel strength and shear strength of conventional adhesives are insufficient. As a result, such applications typically required mechanical bonding, such as ultrasonic welding or a combination of mechanical bonding with an adhesive assist. The equipment used in such applications, however, is often costly requires frequent maintenance, and can limit line speed.
BRIEF SUMMARY OF THE INVENTION
The present invention is directed to a hot melt adhesive composition which possesses certain physical properties that makes it ideally suited for use with nonwoven disposable articles. More particularly, the hot melt adhesive of the present invention maintains acceptable bond strength when subjected to severe peel and/or shear loads at elevated temperatures for extended periods of time. The adhesives of the present invention are thus suitable for use in nonwoven applications which currently rely on mechanical bonding techniques or a combination of mechanical bonding with an adhesive assist. The adhesives of the present invention have a viscosity of less than 25,000 cP at 350° F., and a melt point higher than 250° F.
The hot melt adhesive composition of this invention can be especially useful in applications in disposable nonwoven articles such as diapers or training pants. In particular, the adhesive composition is suitable to bond various laminates of elastic or non-elastic materials. More specifically, the adhesive may be used to bond elastic diaper side panels to various substrates such as nonwoven, polyethylene, polypropylene, and the like.
The hot melt composition of this invention also provides excellent construction bonds when tested via standard peel strength tests. In addition, these adhesives have physical properties which make them easily processable in conventional hot melt equipment.
The hot melt adhesive composition of the present invention comprises a blend of the following ingredients:
(a) about 15% to 65% by weight of a polybutylene homopolymer or copolymer;
(b) about 0.1% to about 3% by weight of a stabilizer; and
the remaining ingredients, depending upon the specific end use and properties desired, being chosen from one or more of the following components so that the ingredients comprise 100% by weight based on the weight of the entire composition:
(c) about 0% to 70% by weight of a polyolefin polymer;
(d) about 0% to 60% by weight of a tackifying resin;
(e) about 0% to 30% by weight of a plasticizer; and
(f) about 0% to 20% by weight of a wax.
The minimum polybutylene polymer content in the composition should be about 15% by weight.
A preferred hot melt adhesive composition functioning without a plasticizer to provide adequate bond strength under extreme peel and shear loads at elevated temperature for extended periods of time comprises a blend of the following:
(a) about 19.9% by weight of a polybutylene homopolymer;
(b) about 29.9% by weight of a tackifying resin;
(c) about 39.8% by weight of a polyolefin copolymer;
(d) about 9.5% by weight of a polyethylene wax; and
(e) about 0.9% by weight of a stabilizer.
Another hot melt adhesive composition functioning without a plasticizer comprises a blend of the following:
(a) about 25% by weight of a blend of polybutylene homopolymer and copolymer;
(b) about 25% by weight of a tackifying resin;
(c) about 19.5% by weight of a wax;
(d) about 30% by weight of a polyolefin polymer; and
(e) about 0.5% by weight of a stabilizer.
A preferred hot melt adhesive composition functioning without wax and without a plasticizer while providing adequate bond strength comprises a blend of the following:
(a) about 20% by weight of a polybutylene homopolymer;
(b) about 30% by weight of a tackifying resin;
(c) about 29% by weight of a polyolefin copolymer;
(d) about 1% by weight of a stabilizer; and
(e) about 20% by weight of a polybutylene copolymer.
A preferred hot melt adhesive composition functioning without a polyolefin polymer while providing adequate bond strength under extreme peel and shear loads at elevated temperatures comprises a blend of the following:
(a) about 50% by weight of a polybutylene copolymer;
(b) about 15% by weight of a tackifying resin;
(c) about 15% by weight of a plasticizer;
(d) about 19.5% by weight of a wax; and
(e) about 0.5% by weight of a stabilizer.
A preferred hot melt adhesive composition functioning without a tackifying resin or a polyolefin polymer while providing adequate bond strength under extreme peel and shear loads at elevated temperatures comprises a blend of the following:
(a) about 65% by weight of a polybutylene copolymer;
(b) about 19.5% by weight of a wax;
(c) about 15% by weight of a plasticizer; and
(d) about 0.5% by weight of a stabilizer.
The hot melt adhesive compositions of the present invention thus provide bonds with excellent resistance to peel and shear forces at elevated temperatures for extended periods of time, and provide an alternative to mechanical bonding, especially of laminates, in a nonwoven disposable article. The prefered adhesive compositions are formulated so as to withstand a peel mode force of 500 grams at 100° F. for a minimum of about 11 hours and further withstands a shear mode force of 1000 grams at 100° F. for a minimum of about 11 hours.
REFERENCES:
patent: 4761450 (1988-08-01), Lakshmanan et al.
patent: 4826909 (1989-05-01), Lakshmanan et al.
patent: 4833192 (1989-05-01), Lakshmanan et al.
patent: 4937138 (1990-06-01), Mostert
patent: 4956207 (1990-09-01), Kaufman et al.
patent: 5024888 (1991-06-01), Hwo et al.
patent: 5041492 (1991-08-01), Koprowicz et al.
patent: 5106447 (1992-04-01), Di Rado et al.
patent: 5256717 (1993-10-01), Stauffer et al.
patent: 5455111 (1995-10-01), Urey
pate
Alper Mark
Fralich Margaret M.
Andrus Sceales Starke & Sawall LLP
Ato Findley Inc.
Yoon Tae
LandOfFree
Hot melt adhesive with high peel and shear strengths for... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Hot melt adhesive with high peel and shear strengths for..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Hot melt adhesive with high peel and shear strengths for... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2547918