Plastic and nonmetallic article shaping or treating: processes – Mechanical shaping or molding to form or reform shaped article – Reshaping running or indefinite-length work
Reexamination Certificate
1999-06-16
2001-04-10
Tentoni, Leo B. (Department: 1732)
Plastic and nonmetallic article shaping or treating: processes
Mechanical shaping or molding to form or reform shaped article
Reshaping running or indefinite-length work
Reexamination Certificate
active
06214274
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a process for densifying an absorbent web. More particularly, the present invention relates to a process for densifying a web which contains superabsorbent material. The densified web can advantageously exhibit desired levels of strength, softness and flexibility.
BACKGROUND OF THE INVENTION
The performance objectives of disposable absorbent articles, such as infant diapers, include leakage prevention, dry feel to the wearer, and a comfortable fit throughout the product life. Accordingly, absorbent articles have typically contained an absorbent core to provide liquid handling and other absorbent functionalities required to meet the product performance objectives. The absorbent core of a conventional absorbent article has typically been composed of absorbent fibers, and a superabsorbent material has typically been combined with the absorbent fibers to increase the liquid absorbent capacity. The absorbent core has been formed in a substantially rectangular shape. The absorbent core has also been formed in an hourglass shape, a I-shape, a T-shape, or similar configuration with a reduced absorbent width in the central crotch region for improved fit and comfort.
Conventional absorbent cores have incorporated dry-formed materials which have been produced with various conventional airlaying techniques. The airlaying techniques have typically laid an air-directed mixture of absorbent fibers and superabsorbent to form a web of the absorbent material. When dry, the conventional dry-formed absorbent structures have been soft and conformable, but have had low strength. In addition, the dry-formed structures have had low integrity after they have been wetted.
Conventional absorbent cores have also incorporated wet-formed materials which have been produced with various wet-laying techniques. The wet-laying techniques have typically formed an absorbent web produced from a precursor material composed of a mixture of fibers and superabsorbent particles combined with water or other aqueous liquid. A particular wet-laying technique has processed the precursor material into a foam, and the foam has then been employed to form the desired web of absorbent material. The absorbent structures produced from wet-formed absorbent materials have had greater strength and greater integrity. In particular, the wet-formed absorbent structures have exhibited greater strength and greater integrity after the absorbent materials have absorbed liquid. The wet-formed absorbent materials, however, have also had excessive stiffness and rigidity, particularly when the absorbent materials have been provided at the basis weights and amounts needed to provide desired levels of total absorbent capacity.
Particular methods for reducing the stiffness of absorbent web materials have included a passing of the material through the nip of a pair of counter-rotating compression rollers. Other methods have embossed the webs to impart increased flexibility. Still other methods have included a passing of the material through the nip of a pair of counter-rotating rollers having textured outer surfaces. The textured surfaces have been configured to produce localized stresses and localized strains which have helped to reduce the rigidity of the material. Where the webs contain superabsorbent particles, the compression rollers have been configured to fracture or crush the superabsorbent materials.
Conventional techniques, such as those mentioned above, have not been adequate for softening or compressing webs which contain superabsorbent materials. The conventional techniques have caused excessive fracturing of the superabsorbents and have increased the relative proportions of smaller superabsorbent particles in the webs. This change in the size distributions of the superabsorbent particles has adversely affected the absorbent properties of the web, has increased the tendency of the superabsorbent to shake-out of the web, and has allowed the generation of excessive dust. In addition, the fracturing of the superabsorbent material has adversely affected various absorbent properties, such as the intake rate of the superabsorbent and the ability of the superabsorbent to swell under pressure.
As a result, there remains a need for improved methods for compressing or otherwise processing stiff absorbent materials to improve the strength, softness, flexibility, wet integrity and absorbent capacity of the materials.
BRIEF DESCRIPTION OF THE INVENTION
Generally stated, the present invention can provide a process for compacting and/or densifying a web which contains a superabsorbent material. In particular aspects, the process includes a compressing of a web which includes a plasticized superabsorbent material. In further aspects, the web can be compressed at a relatively low pressure which can be selected to substantially avoid an excessive damaging of the superabsorbent material.
In its various aspects, the present invention can more effectively and efficiently compact and/or density a web which contains particles of superabsorbent material. In particular, the compacting or densifying process of the invention can advantageously maintain the desired sizes, shapes, physical properties and absorbent properties of the superabsorbent material in the final, compressed web. When articles incorporate the absorbent structures that are produced in accordance with the present invention, the articles can exhibit increased strength, improved fit, reduced leakage, and reduced clumping, bunching or sagging during use.
REFERENCES:
patent: 3881490 (1975-05-01), Whitehead et al.
patent: 3901236 (1975-08-01), Assarsson et al.
patent: 3902230 (1975-09-01), Schwarz
patent: 4076663 (1978-02-01), Masuda et al.
patent: 4117184 (1978-09-01), Erickson et al.
patent: 4223059 (1980-09-01), Schwarz
patent: 4260443 (1981-04-01), Lindsay et al.
patent: 4285100 (1981-08-01), Schwarz
patent: 4286082 (1981-08-01), Tsubakimoto et al.
patent: 4326527 (1982-04-01), Wollangk et al.
patent: 4347092 (1982-08-01), Hlaban et al.
patent: 4354901 (1982-10-01), Kopolow
patent: 4500316 (1985-02-01), Damico
patent: 4552618 (1985-11-01), Kopolow
patent: 4573988 (1986-03-01), Pieniak et al.
patent: 4600458 (1986-07-01), Kramer et al.
patent: 4605402 (1986-08-01), Iskra
patent: 4610678 (1986-09-01), Weisman et al.
patent: 4646362 (1987-03-01), Heran et al.
patent: 4663220 (1987-05-01), Wisneski et al.
patent: 4685914 (1987-08-01), Holtman
patent: 4699823 (1987-10-01), Kellenberger et al.
patent: 4701177 (1987-10-01), Ellis et al.
patent: 4704116 (1987-11-01), Enloe
patent: 4753646 (1988-06-01), Enloe
patent: 4851069 (1989-07-01), Packard et al.
patent: 4886512 (1989-12-01), Damico et al.
patent: 4916005 (1990-04-01), Lippert et al.
patent: 4921543 (1990-05-01), Omran et al.
patent: 4921643 (1990-05-01), Walton et al.
patent: 4938753 (1990-07-01), Van Gompel et al.
patent: 4940464 (1990-07-01), Van Gompel et al.
patent: 4986882 (1991-01-01), Mackey et al.
patent: 5019073 (1991-05-01), Roessler et al.
patent: 5049235 (1991-09-01), Barcus et al.
patent: 5102501 (1992-04-01), Eber et al.
patent: 5226992 (1993-07-01), Morman
patent: 5252275 (1993-10-01), Sultze et al.
patent: 5324575 (1994-06-01), Sultze et al.
patent: 5399219 (1995-03-01), Roessler et al.
patent: 5401267 (1995-03-01), Couture-Dorschner
patent: 5411497 (1995-05-01), Tanzer et al.
patent: 5425725 (1995-06-01), Tanzer et al.
patent: 5433715 (1995-07-01), Tanzer et al.
patent: 5486166 (1996-01-01), Bishop et al.
patent: 5490846 (1996-02-01), Ellis et al.
patent: 5509915 (1996-04-01), Hanson et al.
patent: 5540796 (1996-07-01), Fries
patent: 5558659 (1996-09-01), Sherrod et al.
patent: 5562645 (1996-10-01), Tanzer et al.
patent: 5562650 (1996-10-01), Everett et al.
patent: 5593399 (1997-01-01), Tanzer et al.
patent: 5595618 (1997-01-01), Fries et al.
patent: 5601542 (1997-02-01), Melius et al.
patent: 5605735 (1997-02-01), Zehner et al.
patent: 5607550 (1997-03-01), Akers
patent: 5624429 (1997-04-01), Long et al.
patent: 5651862 (1997-07-01), Anderson et al.
patent: 5669901 (199
Fell David Arthur
Melius Shannon Kathleen
Ramaswami Wallajapet Palani Raj
Reeves William Grover
Sanders Donald Joseph
Kimberly--Clark Worldwide, Inc.
Tentoni Leo B.
Yee Paul
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