Stock material or miscellaneous articles – Web or sheet containing structurally defined element or...
Reexamination Certificate
2000-08-25
2001-07-17
Acquah, Samuel A. (Department: 1711)
Stock material or miscellaneous articles
Web or sheet containing structurally defined element or...
C525S437000, C528S491000, C428S113000, C428S119000, C428S137000, C428S364000, C604S365000, C604S366000, C604S367000, C604S370000, C604S372000, C264S176100, C264S211120, C264S211210, C264S211220
Reexamination Certificate
active
06261677
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Technical Field
This invention relates to a novel synthetic fiber. In one aspect, this invention relates to a nonwoven web formed from the novel synthetic fibers composed of a specified thermoplastic composition.
2. Background
Disposable absorbent products currently find widespread use in many applications. In the infant care and child care markets, disposable diapers and training pants have replaced reusable cloth absorbent articles. Other widely successful disposable absorbent products include feminine care products such as sanitary napkins or tampons, adult incontinence products, and health care products such as surgical drapes or wound dressings.
A disposable absorbent product includes a composite structure including a topsheet, a backsheet, and an absorbent structure between the topsheet and backsheet. The disposable absorbent products include some type of fastening system for fitting the product onto the wearer.
Disposable absorbent products are subjected to one or more liquid insults, such as of water, urine, menses, or blood, during use. As such, the outer cover backsheet materials of the disposable absorbent products are made of liquid insoluble and liquid impermeable materials, such as polyolefin films, having sufficient strength and handling capability so that the disposable absorbent product retains its integrity during use by a wearer and does not allow leakage of the liquid insulting the product.
INTRODUCTION TO THE INVENTION
Although currently available disposable baby diapers and other disposable absorbent products have been accepted by the public, these current products still have need of improvement in specific areas. Many disposable absorbent products can be difficult to dispose. Attempts to flush many disposable absorbent products down a toilet into a sewage system may lead to blockage of the toilet or pipes connecting the toilet to the sewage system. The outer cover materials in the disposable absorbent products in particular do not disintegrate or disperse when flushed down a toilet so that the disposable absorbent product cannot be disposed in this way. If the outer cover materials are made very thin to reduce the overall bulk in an attempt to reduce the likelihood of blockage of a toilet or a sewage pipe, then the outer cover material does not exhibit sufficient strength to prevent tearing or ripping as the outer cover material is subjected to the stresses of normal use by a wearer.
Solid waste disposal is becoming an ever increasing problem throughout the world. As landfills continue to fill up, a demand has increased for a material source reduction in disposable products. As an alternative, recyclable or biodegradable components are needed to be developed for incorporating into the disposable products. As an alternative, products are needed to be developed for final disposal by means other than by incorporation into solid waste disposal facilities such as landfills.
Accordingly, there is a need for new materials to be used in disposable absorbent products which retain integrity and strength during use, but after such use, the materials may be disposed more efficiently. There is a need for new materials used in the disposable absorbent product to be disposed easily and efficiently by composting. Alternatively, the disposable absorbent product may be disposed easily and efficiently in a liquid sewage system wherein the disposable absorbent product is capable of being degraded.
Problems have been encountered with fibers prepared from aliphatic polyesters. Aliphatic polyester polymers have been observed to exhibit a relatively slow crystallization rate as compared to polyolefin polymers. The slow crystallization rate causes poor processability of the aliphatic polyester polymers.
The aliphatic polyester polymers do not provide sufficient thermal-dimensional stability. The aliphatic polyester polymers undergo severe heat shrinkage because of a relaxation of the polymer chain during downstream heat treatment processes, such as thermal bonding and lamination, unless an extra step such as heat setting is taken. However, a heat setting step limits the use of the fiber in in-situ nonwoven forming processes, such as spunbond and meltblown, where heat setting is very difficult. Moreover, the use of processing additives retards the biodegradation rate of the original material, or the processing additives themselves may not be biodegradable.
It is an object of the present invention to provide a novel synthetic fiber.
It is another object of the present invention to provide a novel synthetic fiber incorporating a specified thermoplastic composition.
It is an object of the present invention to provide a novel synthetic fiber incorporating a thermoplastic composition providing preferred processability.
It is an object of the present invention to provide a novel synthetic fiber incorporating a thermoplastic composition having a specified reduced crystal size.
It is an object of the present invention to provide a novel synthetic fiber incorporating a thermoplastic composition having preferred thermal dimensional-stability.
It is an object of the present invention to provide a novel synthetic fiber incorporating a thermoplastic composition having preferred biodegradability.
It is an object of the present invention to provide an absorbent article formed by the novel synthetic fiber incorporating a thermoplastic composition having preferred processability, thermal dimensional-stability, and biodegradability.
It is also an object of the present invention to provide a nonwoven structure formed from a novel synthetic fiber.
It is also an object of the present invention to provide a nonwoven web formed from a novel synthetic fiber.
It is a further object of the present invention to provide an absorbent article formed from and incorporating a novel synthetic fiber.
It is a further object of the present invention to provide an absorbent article formed from a nonwoven structure incorporating a novel synthetic fiber.
It is a further object of the present invention to provide an absorbent article formed from a nonwoven web incorporating a novel synthetic fiber.
It is an object of the present invention to provide a fiber or nonwoven structure which is degradable in the environment.
It is a further object of the present invention to provide an absorbent article formed from a nonwoven web incorporating a novel synthetic fiber which is degradable in the environment.
These and other objects of the present invention will become more apparent from a careful inspection of the detailed description and the figure of the drawings which follow.
SUMMARY OF THE INVENTION
The present invention provides a novel synthetic fiber including a first component of an aliphatic polyester polymer and a second component of a multicarboxylic acid and melt blending the unreacted specified thermoplastic composition in an extruder. In one aspect, the present invention provides a novel synthetic fiber formed by dry mixing the first component aliphatic polyester polymer and the second component multicarboxylic acid to form an unreacted specified thermoplastic composition. The second component multicarboxylic acid both lubricates the extruder and provides a nucleating agent for crystallizing the specified thermoplastic composition to form a mean crystal size less than about 120 Angstroms. Novel fiber composed of the specified thermoplastic composition has a mean crystal size less than about 120 Angstroms. The novel fiber has a glass transition temperature (Tg) lower than the Tg of the fiber without the multicarboxylic acid. In one aspect, the fiber has a glass transition temperature (Tg) less than about 55° C.
In one aspect, a first component of polylactic acid and a second component of adipic acid provide synthetic fibers in a nonwoven structure used in a biodegradable and compostable disposable absorbent product for the absorption and removal of body fluids.
REFERENCES:
patent: 3853820 (1974-12-01), Vachon
patent: 3921333 (1975-11-01), Clendenning et al.
patent: 3964486 (1976-06
Etzel Brian Thomas
Tsai Fu-Jya Daniel
Acquah Samuel A.
Connelly Thomas J
Glantz Douglas G.
Kimberly--Clark Worldwide, Inc.
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