Elastic materials with improved performance at body temperature

Details Elastic materials with improved performance at body temperature Elastic materials with improved performance at body temperature

1997-05-13

2001-02-13

Weisberger, Richard (Department: 1774)

Stock material or miscellaneous articles

Web or sheet containing structurally defined element or...

C428S221000, C428S910000, C428S119000, C525S089000, C525S095000, C525S098000

Reexamination Certificate

active

06187425

ABSTRACT:

FIELD OF INVENTION
The present invention pertains to polymeric materials with improved elastic performance at body temperature and laminates thereof. The polymeric materials of the present invention are particularly useful in disposable personal care products in which good body conformance and retention of product shape over time, at body temperature, are required.
BACKGROUND OF THE INVENTION
Polymeric materials have a wide variety of uses, especially in the areas of absorbent articles and disposable items. As used herein, the term “absorbent articles” refers to devices which absorb and contain body exudates and, more specifically, refers to devices that are placed against or in proximity to the body of the wearer to absorb and contain the various exudates discharged from the body. The term “absorbent articles” is intended to include diapers, training pants, absorbent underpants, incontinence products, bandages and the like. The term “disposable” is used herein to describe articles not intended to be laundered or otherwise restored or reused, such as protective articles including industrial work wear and medical garments such as surgical drapes and gowns, as well as other articles of clothing either as the entire article or simply as a component thereof.
Thermally and solution-processed elastomers are commonly used in disposable personal care absorbent articles for waist bands, side panels and other gasketing applications. In the case of waist bands and side panels, the elastomer functions to hold the article in place during and under actual use conditions. Actual use conditions typically involve heat, humidity, loading or any combination thereof. In the case of gaskets, the elastomer functions to hold the disposable personal care absorbent article closer to the wearer's skin and thereby prevent leakage. The gaskets also manage some stress and prevent sagging of the absorbent article over a certain period of time. Some of these elastomers, however, lose their elastic properties after a period of exposure to actual use conditions.
Lycra strand is an excellent elastomer and performs well at body temperature. The superior elastic properties result from the well-defined, phase-segregated molecular structure of Lycra strand. In general, Lycra strand is a two-phase polymer system having a hard phase and a soft phase. The phase segregation occurs between the hard and soft rubber segments which constitute the backbone of the polymer. Lycra strand behaves almost like an ideal elastomer because of the substantial difference in the glass transition, or melting point, of the rubber block and the glass transition of the urea, hard segment. Lycra strand, however, is expensive because (1) it is produced by wet spinning and (2) there is a lack of competitive products on the market.
There are other block copolymers based on urethane or ester that attempt to take advantage of the concept of phase segregation. These copolymers include polyurethane elastomeric materials such as, for example, those available under the trademark ESTANE® from B. F. Goodrich & Company of Akron, Ohio and those available under the trademark MORTHANE® from Morton International, Inc. of Seabrook, New Hampshire and polyester elastomeric materials such as, for example, those available under the trade designation HYTREL® from E. I. Dupont de Nemours & Company of Wilmington, Del. and those known as ARNITEL®, formerly available from Akzo Plastics of Arnhem, Holland and now available from DSM of Sittard, Holland. Such urethane and ester copolymers, while capable of delivering excellent elastic properties, can be costly. They are, therefore, not always cost effective for use in the business of disposable personal care absorbent articles.
Thermoplastic block copolymer elastomers based on blocks of polystyrene and rubber blocks of isoprene, butadiene, siloxane, amorphous ethylene, propylene or a combination of amorphous ethylene and propylene, are attractive for use in disposable personal care absorbent articles because of the lower cost, the ease of processing and the non-toxicity. However, at body temperature, these copolymers lose their elastic properties and dimensional stability after a period of time and begin to sag and leak. The loss of elastic properties and dimensional stability appears to be associated with the polymer itself. The segments of polystyrene begin to flow and slip at the normal human body temperature, especially under tension or load. The motion of the styrene blocks adversely affects the elastic character of the polymer, resulting in the loss of dimensional stability and elastic properties.
A need, therefore, exists for a cost-effective polymer that retains its elastic properties while also having increased mechanical properties and that is useful personal care absorbent articles such as diapers, training pants, incontinence devices and the like.
Similarly, in protective articles such as industrial work wear and medical garments, the motion of the styrene blocks adversely affects the elastic character of the polymer, resulting in the loss of dimensional stability and shape. A need, therefore, exists for a polymer that imparts improved in-use durability to such protective articles.
SUMMARY OF THE INVENTION
It has now been discovered that preventing the flow of styrene blocks results in a polymeric material with significantly improved retention of elastic properties and improved performance at body temperature. Thus, in accordance with the present invention, polymeric material is derived from styrene block copolymers blended with polyphenylene ether. Polyphenylene ether is a high performance thermoplastic having relatively high melt viscosities, a high glass transition temperature (typically, T
g
=210° C., but T
g
may vary as a function of molecular weight) and a high softening temperature (T
g
≧275° C.).
As used herein, the term “dimensionally stable” means resistant to creep or able to retain its shape as a function of time under actual use conditions.
As used herein, the term “body temperature” means about 98.6° F. ±4° F.
Polymeric materials produced according to the present invention may be used as elastic components of personal care absorbent articles such as, for example, in the side panels of diapers and training pants, as well as in the leg elastic and gasketing of diapers, training pants, incontinence devices and the like. They may also be used in protective garments such as industrial work wear and surgical drapes and gowns.


REFERENCES:
patent: 3383435 (1968-05-01), Cizek
patent: 3994856 (1976-11-01), Katchman et al.
patent: 4167507 (1979-09-01), Haaf
patent: 4259220 (1981-03-01), Bunnelle et al.
patent: 4313864 (1982-02-01), Haaf et al.
patent: 4383082 (1983-05-01), Lee, Jr.
patent: 4414970 (1983-11-01), Berry
patent: 4418123 (1983-11-01), Bunnelle et al.
patent: 4421883 (1983-12-01), Cooper et al.
patent: 4423187 (1983-12-01), Brandstetter et al.
patent: 4525407 (1985-06-01), Ness
patent: 4525508 (1985-06-01), Lee, Jr.
patent: 4543099 (1985-09-01), Bunnelle et al.
patent: 4544703 (1985-10-01), Haaf
patent: 4719261 (1988-01-01), Bunnelle et al.
patent: 4728461 (1988-03-01), Fujii et al.
patent: 4816345 (1989-03-01), Jadamus et al.
patent: 4866129 (1989-09-01), Brandstetter et al.
patent: 4910064 (1990-03-01), Sabee
patent: 4957799 (1990-09-01), Miyamoto et al.
patent: 4977011 (1990-12-01), Smith
patent: 5059645 (1991-10-01), Ostermayer et al.
patent: 5093422 (1992-03-01), Himes
patent: 5100959 (1992-03-01), Okada et al.
patent: 5109068 (1992-04-01), Yamasaki et al.
patent: 5109069 (1992-04-01), Shibata et al.
patent: 5118748 (1992-06-01), Fujita et al.
patent: 5124415 (1992-06-01), Sakamoto et al.
patent: 5166264 (1992-11-01), Lee, Jr. et al.
patent: 5189099 (1993-02-01), Arnold-Mauer et al.
patent: 5209801 (1993-05-01), Smith
patent: 5288791 (1994-02-01), Collier, IV et al.
patent: 5296540 (1994-03-01), Akiyama et al.
patent: 5304599 (1994-04-01), Himes
patent: 5324782 (1994-06-01), Lee, Jr.
patent: 5397822 (1995-03-01), Lee, Jr.
patent: 5418275 (1995-05-01), Okada et a

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