Classifications

• • D—TEXTILES; PAPER
  • D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
  • D01F—CHEMICAL FEATURES IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS; APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OF CARBON FILAMENTS
  • D01F8/00—Conjugated, i.e. bi- or multicomponent, artificial filaments or the like; Manufacture thereof
  • D01F8/04—Conjugated, i.e. bi- or multicomponent, artificial filaments or the like; Manufacture thereof from synthetic polymers
  • D01F8/12—Conjugated, i.e. bi- or multicomponent, artificial filaments or the like; Manufacture thereof from synthetic polymers with at least one polyamide as constituent
• • D—TEXTILES; PAPER
  • D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
  • D01F—CHEMICAL FEATURES IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS; APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OF CARBON FILAMENTS
  • D01F8/00—Conjugated, i.e. bi- or multicomponent, artificial filaments or the like; Manufacture thereof
  • D01F8/04—Conjugated, i.e. bi- or multicomponent, artificial filaments or the like; Manufacture thereof from synthetic polymers
  • D01F8/06—Conjugated, i.e. bi- or multicomponent, artificial filaments or the like; Manufacture thereof from synthetic polymers with at least one polyolefin as constituent
• • D—TEXTILES; PAPER
  • D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
  • D01F—CHEMICAL FEATURES IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS; APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OF CARBON FILAMENTS
  • D01F8/00—Conjugated, i.e. bi- or multicomponent, artificial filaments or the like; Manufacture thereof
  • D01F8/04—Conjugated, i.e. bi- or multicomponent, artificial filaments or the like; Manufacture thereof from synthetic polymers
  • D01F8/10—Conjugated, i.e. bi- or multicomponent, artificial filaments or the like; Manufacture thereof from synthetic polymers with at least one other macromolecular compound obtained by reactions only involving carbon-to-carbon unsaturated bonds as constituent
• • D—TEXTILES; PAPER
  • D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
  • D01F—CHEMICAL FEATURES IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS; APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OF CARBON FILAMENTS
  • D01F8/00—Conjugated, i.e. bi- or multicomponent, artificial filaments or the like; Manufacture thereof
  • D01F8/04—Conjugated, i.e. bi- or multicomponent, artificial filaments or the like; Manufacture thereof from synthetic polymers
  • D01F8/14—Conjugated, i.e. bi- or multicomponent, artificial filaments or the like; Manufacture thereof from synthetic polymers with at least one polyester as constituent
• • D—TEXTILES; PAPER
  • D04—BRAIDING; LACE-MAKING; KNITTING; TRIMMINGS; NON-WOVEN FABRICS
  • D04H—MAKING TEXTILE FABRICS, e.g. FROM FIBRES OR FILAMENTARY MATERIAL; FABRICS MADE BY SUCH PROCESSES OR APPARATUS, e.g. FELTS, NON-WOVEN FABRICS; COTTON-WOOL; WADDING ; NON-WOVEN FABRICS FROM STAPLE FIBRES, FILAMENTS OR YARNS, BONDED WITH AT LEAST ONE WEB-LIKE MATERIAL DURING THEIR CONSOLIDATION
  • D04H1/00—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres
  • D04H1/40—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties
  • D04H1/42—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties characterised by the use of certain kinds of fibres insofar as this use has no preponderant influence on the consolidation of the fleece
  • D04H1/4282—Addition polymers
  • D04H1/4291—Olefin series
• • D—TEXTILES; PAPER
  • D04—BRAIDING; LACE-MAKING; KNITTING; TRIMMINGS; NON-WOVEN FABRICS
  • D04H—MAKING TEXTILE FABRICS, e.g. FROM FIBRES OR FILAMENTARY MATERIAL; FABRICS MADE BY SUCH PROCESSES OR APPARATUS, e.g. FELTS, NON-WOVEN FABRICS; COTTON-WOOL; WADDING ; NON-WOVEN FABRICS FROM STAPLE FIBRES, FILAMENTS OR YARNS, BONDED WITH AT LEAST ONE WEB-LIKE MATERIAL DURING THEIR CONSOLIDATION
  • D04H1/00—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres
  • D04H1/40—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties
  • D04H1/42—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties characterised by the use of certain kinds of fibres insofar as this use has no preponderant influence on the consolidation of the fleece
  • D04H1/4326—Condensation or reaction polymers
  • D04H1/4334—Polyamides
• • D—TEXTILES; PAPER
  • D04—BRAIDING; LACE-MAKING; KNITTING; TRIMMINGS; NON-WOVEN FABRICS
  • D04H—MAKING TEXTILE FABRICS, e.g. FROM FIBRES OR FILAMENTARY MATERIAL; FABRICS MADE BY SUCH PROCESSES OR APPARATUS, e.g. FELTS, NON-WOVEN FABRICS; COTTON-WOOL; WADDING ; NON-WOVEN FABRICS FROM STAPLE FIBRES, FILAMENTS OR YARNS, BONDED WITH AT LEAST ONE WEB-LIKE MATERIAL DURING THEIR CONSOLIDATION
  • D04H1/00—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres
  • D04H1/40—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties
  • D04H1/42—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties characterised by the use of certain kinds of fibres insofar as this use has no preponderant influence on the consolidation of the fleece
  • D04H1/4326—Condensation or reaction polymers
  • D04H1/435—Polyesters
• • D—TEXTILES; PAPER
  • D04—BRAIDING; LACE-MAKING; KNITTING; TRIMMINGS; NON-WOVEN FABRICS
  • D04H—MAKING TEXTILE FABRICS, e.g. FROM FIBRES OR FILAMENTARY MATERIAL; FABRICS MADE BY SUCH PROCESSES OR APPARATUS, e.g. FELTS, NON-WOVEN FABRICS; COTTON-WOOL; WADDING ; NON-WOVEN FABRICS FROM STAPLE FIBRES, FILAMENTS OR YARNS, BONDED WITH AT LEAST ONE WEB-LIKE MATERIAL DURING THEIR CONSOLIDATION
  • D04H1/00—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres
  • D04H1/40—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties
  • D04H1/42—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties characterised by the use of certain kinds of fibres insofar as this use has no preponderant influence on the consolidation of the fleece
  • D04H1/4382—Stretched reticular film fibres; Composite fibres; Mixed fibres; Ultrafine fibres; Fibres for artificial leather
  • D04H1/43825—Composite fibres
  • D04H1/43828—Composite fibres sheath-core
• • D—TEXTILES; PAPER
  • D04—BRAIDING; LACE-MAKING; KNITTING; TRIMMINGS; NON-WOVEN FABRICS
  • D04H—MAKING TEXTILE FABRICS, e.g. FROM FIBRES OR FILAMENTARY MATERIAL; FABRICS MADE BY SUCH PROCESSES OR APPARATUS, e.g. FELTS, NON-WOVEN FABRICS; COTTON-WOOL; WADDING ; NON-WOVEN FABRICS FROM STAPLE FIBRES, FILAMENTS OR YARNS, BONDED WITH AT LEAST ONE WEB-LIKE MATERIAL DURING THEIR CONSOLIDATION
  • D04H1/00—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres
  • D04H1/40—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties
  • D04H1/42—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties characterised by the use of certain kinds of fibres insofar as this use has no preponderant influence on the consolidation of the fleece
  • D04H1/4382—Stretched reticular film fibres; Composite fibres; Mixed fibres; Ultrafine fibres; Fibres for artificial leather
  • D04H1/43835—Mixed fibres, e.g. at least two chemically different fibres or fibre blends
• • D—TEXTILES; PAPER
  • D04—BRAIDING; LACE-MAKING; KNITTING; TRIMMINGS; NON-WOVEN FABRICS
  • D04H—MAKING TEXTILE FABRICS, e.g. FROM FIBRES OR FILAMENTARY MATERIAL; FABRICS MADE BY SUCH PROCESSES OR APPARATUS, e.g. FELTS, NON-WOVEN FABRICS; COTTON-WOOL; WADDING ; NON-WOVEN FABRICS FROM STAPLE FIBRES, FILAMENTS OR YARNS, BONDED WITH AT LEAST ONE WEB-LIKE MATERIAL DURING THEIR CONSOLIDATION
  • D04H1/00—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres
  • D04H1/40—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties
  • D04H1/54—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties by welding together the fibres, e.g. by partially melting or dissolving
• • D—TEXTILES; PAPER
  • D04—BRAIDING; LACE-MAKING; KNITTING; TRIMMINGS; NON-WOVEN FABRICS
  • D04H—MAKING TEXTILE FABRICS, e.g. FROM FIBRES OR FILAMENTARY MATERIAL; FABRICS MADE BY SUCH PROCESSES OR APPARATUS, e.g. FELTS, NON-WOVEN FABRICS; COTTON-WOOL; WADDING ; NON-WOVEN FABRICS FROM STAPLE FIBRES, FILAMENTS OR YARNS, BONDED WITH AT LEAST ONE WEB-LIKE MATERIAL DURING THEIR CONSOLIDATION
  • D04H1/00—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres
  • D04H1/40—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties
  • D04H1/58—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties by applying, incorporating or activating chemical or thermoplastic bonding agents, e.g. adhesives
  • D04H1/587—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties by applying, incorporating or activating chemical or thermoplastic bonding agents, e.g. adhesives characterised by the bonding agents used
• • D—TEXTILES; PAPER
  • D04—BRAIDING; LACE-MAKING; KNITTING; TRIMMINGS; NON-WOVEN FABRICS
  • D04H—MAKING TEXTILE FABRICS, e.g. FROM FIBRES OR FILAMENTARY MATERIAL; FABRICS MADE BY SUCH PROCESSES OR APPARATUS, e.g. FELTS, NON-WOVEN FABRICS; COTTON-WOOL; WADDING ; NON-WOVEN FABRICS FROM STAPLE FIBRES, FILAMENTS OR YARNS, BONDED WITH AT LEAST ONE WEB-LIKE MATERIAL DURING THEIR CONSOLIDATION
  • D04H1/00—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres
  • D04H1/40—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties
  • D04H1/58—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties by applying, incorporating or activating chemical or thermoplastic bonding agents, e.g. adhesives
  • D04H1/64—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties by applying, incorporating or activating chemical or thermoplastic bonding agents, e.g. adhesives the bonding agent being applied in wet state, e.g. chemical agents in dispersions or solutions
• • D—TEXTILES; PAPER
  • D04—BRAIDING; LACE-MAKING; KNITTING; TRIMMINGS; NON-WOVEN FABRICS
  • D04H—MAKING TEXTILE FABRICS, e.g. FROM FIBRES OR FILAMENTARY MATERIAL; FABRICS MADE BY SUCH PROCESSES OR APPARATUS, e.g. FELTS, NON-WOVEN FABRICS; COTTON-WOOL; WADDING ; NON-WOVEN FABRICS FROM STAPLE FIBRES, FILAMENTS OR YARNS, BONDED WITH AT LEAST ONE WEB-LIKE MATERIAL DURING THEIR CONSOLIDATION
  • D04H3/00—Non-woven fabrics formed wholly or mainly of yarns or like filamentary material of substantial length
  • D04H3/08—Non-woven fabrics formed wholly or mainly of yarns or like filamentary material of substantial length characterised by the method of strengthening or consolidating
  • D04H3/12—Non-woven fabrics formed wholly or mainly of yarns or like filamentary material of substantial length characterised by the method of strengthening or consolidating with filaments or yarns secured together by chemical or thermo-activatable bonding agents, e.g. adhesives, applied or incorporated in liquid or solid form
• • D—TEXTILES; PAPER
  • D04—BRAIDING; LACE-MAKING; KNITTING; TRIMMINGS; NON-WOVEN FABRICS
  • D04H—MAKING TEXTILE FABRICS, e.g. FROM FIBRES OR FILAMENTARY MATERIAL; FABRICS MADE BY SUCH PROCESSES OR APPARATUS, e.g. FELTS, NON-WOVEN FABRICS; COTTON-WOOL; WADDING ; NON-WOVEN FABRICS FROM STAPLE FIBRES, FILAMENTS OR YARNS, BONDED WITH AT LEAST ONE WEB-LIKE MATERIAL DURING THEIR CONSOLIDATION
  • D04H3/00—Non-woven fabrics formed wholly or mainly of yarns or like filamentary material of substantial length
  • D04H3/08—Non-woven fabrics formed wholly or mainly of yarns or like filamentary material of substantial length characterised by the method of strengthening or consolidating
  • D04H3/14—Non-woven fabrics formed wholly or mainly of yarns or like filamentary material of substantial length characterised by the method of strengthening or consolidating with bonds between thermoplastic yarns or filaments produced by welding
• • D—TEXTILES; PAPER
  • D04—BRAIDING; LACE-MAKING; KNITTING; TRIMMINGS; NON-WOVEN FABRICS
  • D04H—MAKING TEXTILE FABRICS, e.g. FROM FIBRES OR FILAMENTARY MATERIAL; FABRICS MADE BY SUCH PROCESSES OR APPARATUS, e.g. FELTS, NON-WOVEN FABRICS; COTTON-WOOL; WADDING ; NON-WOVEN FABRICS FROM STAPLE FIBRES, FILAMENTS OR YARNS, BONDED WITH AT LEAST ONE WEB-LIKE MATERIAL DURING THEIR CONSOLIDATION
  • D04H5/00—Non woven fabrics formed of mixtures of relatively short fibres and yarns or like filamentary material of substantial length
  • D04H5/06—Non woven fabrics formed of mixtures of relatively short fibres and yarns or like filamentary material of substantial length strengthened or consolidated by welding-together thermoplastic fibres, filaments, or yarns
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/29—Coated or structually defined flake, particle, cell, strand, strand portion, rod, filament, macroscopic fiber or mass thereof
  • Y10T428/2913—Rod, strand, filament or fiber
  • Y10T428/2929—Bicomponent, conjugate, composite or collateral fibers or filaments [i.e., coextruded sheath-core or side-by-side type]
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T442/00—Fabric [woven, knitted, or nonwoven textile or cloth, etc.]
  • Y10T442/60—Nonwoven fabric [i.e., nonwoven strand or fiber material]
  • Y10T442/637—Including strand or fiber material which is a monofilament composed of two or more polymeric materials in physically distinct relationship [e.g., sheath-core, side-by-side, islands-in-sea, fibrils-in-matrix, etc.] or composed of physical blend of chemically different polymeric materials or a physical blend of a polymeric material and a filler material

Definitions

• the present invention relates to dry laid and wet laid nonwoven webs useful in diapers, incontinent pads, sanitary napkins, and other absorbent pads for liquids.
• these pads usually comprise binder and wood pulp or other absorbent material.
• Making suitable nonwoven webs for these uses requires good adhesion between the binder and the absorbent material.
• the present invention relates to a nonwoven web having improved adhesion based on tackifiers present in the binder.
• Tackifiers include rosin, rosin esters, and terpene based, piperylene based, and hydrocarbon based compounds.
• the binder with tackifier may also contain an adhesion promoter, usually grafted polyolefins, and an enhancement agent, usually inactive inorganic compounds in powder form.
• Nonwoven webs particularly in the form of disposal absorbent articles such as disposable diapers have had much success in the marketplace. However, there is always a need to improve these products and particularly in terms of their adhesion such that they do not fall apart during manufacturing, processing into articles, and during use.
• SAP super absorbent polymer
• a binder such as a bicomponent fiber or a low melt polymer fiber. These existing compositions contained approximately 10% binder and approximately 80 to 90% by weight absorbent.
• nonwoven webs were first created by mixing the wood pulp (and optionally SAP) with the binder. This composition was then introduced into a heating zone, such that the lower melt material of the polymer, or the lower melting material of the bicomponent fiber would melt and coat at least a portion of most of the wood pulp fibers (and any optional SAP). The composition was then introduced into a cooling zone where the lower melting binder material would solidify thereby binding the wood pulp (and optional SAP) into a unitary web structure.
• other fibers may be introduced such as other synthetic fibers or natural fibers to achieve other desired characteristics such as low density, high loft, compression resistance, and fluid uptake rate.
• U.S. Patent 5,981,410 to Hansen, et al. discloses bicomponent fibers blended with cellulose fibers such as pulp fibers or cotton fibers to create a nonwoven web useful in disposable diapers, for example.
• U.S. Patent 5,994,244 to Fujiwara, et al. discloses a nonwoven web comprised of cellulose type fibers such as fluff pulp and low melt fibers useful in producing disposable diapers, among other things. It also discloses the addition of inorganic particle (e.g. TiO 2 ) to the ethylene-acrylic ester-maleic anhydride sheath bicomponent spunbond filament. The particles reduce the adhesion of the filaments during spinning and give a more uniform web.
• inorganic particle e.g. TiO 2
• Suitable bicomponent fibers can be found in U.S. Patent 4,950,541 to Tabor, et al. and U.S. Patent 5,372,885 to Tabor, et al., both of which are hereby incorporated by reference. These patents disclose the use of a low melt maleic acid or maleic anhydride grafted polyethylene.
• U.S. Patent 5,126,201 to Shiba et al. discloses the addition of TiO 2 in both the core and sheath of bicomponent binder fibers to improve the cutting efficiency of nonwoven webs.
• the amount of TiO 2 in the core is >1.5%, preferably there is no TiO 2 in the sheath, since TiO 2 in the sheath reduces adhesion.
• Japanese Patent JP 02-169718 to Matsuo et al. discloses polyolefin sheath/polyester core bicomponent fibers, the sheath containing 0.3-10% of inorganic particles (preferably TiO 2 ) to obtain a better softness and opacity of the web. This patent teaches that the addition of inorganic particles reduce the nonwoven strength.
• the present invention is an improvement over these existing nonwoven web products.
• the present invention improves the adhesion by employing a tackifier.
• Tackifiers include rosin, rosin esters, and terpene based, piperylene based, and hydrocarbon based compounds.
• the present invention relates to either bicomponent fiber or low melt polymer fiber, and tackifier thereby producing a binder with improved adhesion.
• the bicomponent fiber contains a high melting portion and a low melting portion, with the low melting portion containing tackifier. If low melt fiber (instead of bicomponent fiber) was employed it likewise contains tackifier. The tackifier is believed to act as an adhesion promoting agent better binding the absorbent material together into a unitary web.
• the low melt polymer fiber or the low melting portion of the bicomponent fiber is defined as " low melt base”.
• the present invention comprises a binder fiber containing tackifier.
• the binding fiber may be a bicomponent fiber or a typical low melt polymer fiber.
• the low melt base contains the tackifier.
• the binder fiber containing tackifier may optionally contain an adhesion promoter and an enhancement agent.
• the web of the present invention comprises binder fiber containing tackifier and an absorbent.
• the absorbent may be synthetic or natural.
• the present invention also comprises a web comprising from about 5 to about 25% by weight binder fiber and from about 75 to 95% by weight absorbent.
• the absorbent may be a natural absorbent or a super absorbent polymer or a combination of these.
• the binder fiber contains less than about 40% by weight tackifier based on the low melt base.
• Suitable absorbents are natural or synthetic absorbents. Synthetic absorbents are primarily known as super absorbent polymers (SAP). The absorbents comprise 75 - 95 % by weight of the web. Natural absorbents are hydrophilic materials such as cellulosic fibers, wood pulp fluff, cotton, cotton linters, and regenerated cellulose fibers such as rayon, or a mixture of these. Preferred is wood pulp fluff, which is both inexpensive and readily available.
• Absorbent pads employing natural absorbents may not provide adequate fluid intake for all circumstances. Also natural absorbents are very bulky. Accordingly, many absorbent pads employ SAP in relatively low quantities. This is because the cost of SAP is much higher than the cost of natural absorbents. Replacing some of the natural absorbents with SAP can reduce the overall bulk of the pad and/or provide superior fluid intake.
• the term "super absorbent polymer” or “SAP” refers to a water-swellable, generally water-insoluble material capable of absorbing at least about 10, desirably about 20, and preferably about 50 times or more its weight in water.
• the super absorbent polymer may be formed from organic material, which may include natural materials such as agar, pectin, and guar gum, as well as synthetic materials such as synthetic hydrogel polymers.
• Synthetic hydrogel polymers include, for example, carboxymethyl cellulose, alkali metal salts of polyacrylic acid, polyacrylamides, polyvinyl alcohol, ethylene maleic anhydride copolymers, polyvinyl ethers, hydroxypropyl cellulose, polyvinyl morpholinone, polymers and copolymers of vinyl sulfonic acid, polyacrylates, polyacrylamides, polyvinyl pyridine, and the like.
• Other suitable polymers include hydrolyzed acrylonitrile grafted starch, acrylic acid grafted starch, and isobutylene maleic anhydride copolymers and mixtures thereof.
• the hydrogel polymers are preferably lightly crosslinked to render the materials substantially water insoluble.
• Crosslinking may, for example, be by irradiation or covalent, ionic, van der Waals, or hydrogen bonding. Suitable materials are available from various commercial vendors such as the Dow Chemical Company, Allied Colloid, Inc., and Stockhausen, Inc.
• the super absorbent polymer may be in the form of particles, flakes, fibers, rods, films or any of a number of geometric forms.
• the binder fibers of the present invention can either be in the form of a low melt fiber, or a bicomponent fiber.
• the low melting portion of the bicomponent fiber would comprise the same material as the low melt fiber.
• the preferred binder fiber of the present invention is the bicomponent.
• Binder fibers have an average length of from about 3 to about 75 mm. Binder fibers having a denier of between 1 and 10 are preferred.
• the low melt base can be polyolefin, such as polyethylene (PE), polypropylene (PP), polybutylene or a mixture of these.
• Suitable polyethylene may be high density polyethylene (HDPE), medium density polyethylene (MDPE), low density polyethylene (LDPE), linear low density polyethylene (LLDPE), ultra low density polyethylene (ULDPE); or a mixture of these.
• HDPE high density polyethylene
• MDPE medium density polyethylene
• LDPE low density polyethylene
• LLDPE linear low density polyethylene
• ULDPE ultra low density polyethylene
• polyolefins may be produced with either Ziegler-Natta or metallocene catalysts.
• the low melt base can be a low melting polyester such as polybutylene terephthalate (PBT), or polytrimethylene terephthalate (PTT), a low melting copolyester such as copolymers of PET with comonomers such as suitable diol components selected from 1,4-cyclohexanedimenthanol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 2,2-dimenthyl-1, 3-propanediol, 1,6-hexanediol, 1,2-cyclohexanediol, 1,4-cyclohexanediol, 1,2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, and diols containing one or more oxygen atoms in the chain, e.g., diethylene glycol, triethylene glycol, dipropylene glycol, tripropylene glycol, or
• Bicomponent fibers can be of the type in which the low melting portion is adjacent to the high melting portion such as a side-by-side configuration, or a sheath-core configuration where the sheath is the low melting component and the core is the high melting component.
• the high melting portion may be selected from the class of polyolefins, such as polyethylene, polypropylene, and polybutylene; polyesters such as polyethylene terephthalate (PET), polybutylene terephthalate, polyethylene naphthalate, and the like; polyamides such as nylon 6, nylon 66; polyacrylates such as polymethacrylate, polymethylmethacrylate, and the like; as well as mixtures and copolymers of these.
• the low melting portion, in a suitable bicomponent fiber melts at a temperature of at least about 5°C lower than said high melting portion.
• Suitable bicomponent fibers have a low melting portion that comprises from about 5 to about 75% by weight of the bicomponent fiber, with the remainder being the high melting portion. If, for example, a 50-50 bicomponent fiber is employed as the binder fiber, the 50% by weight low melting portion is low melt base polyolefin with less than about 40% by weight tackifier (with or without an adhesion promoter or enhancement agent, or a mixture thereof), and the 50% by weight high melting portion could be PET.
• suitable bicomponent fibers are polyethylene/polypropylene; polyethylene/polyester (especially polyethylene terephthalate); polyethylene/nylon, copolyester/PET; PBT/PET; PTT/PET for example, as well as mixtures of these.
• polyethylene/polyester fibers such as LLDPE/PET or polyethylene/polypropylene, such as LLDPE/PP are used.
• the high melting polyolefin must have a melting point at least about 5 ° C higher than the low melting polyolefin.
• Tackifiers include rosin, rosin esters, and terpene based, piperylene based, and hydrocarbon based compounds.
• Commercially available rosin based tackifiers are known as Foral 85 made by Hercules, Inc.; Permalyn 2085 made by Eastman Chemicals; or Escorez 5400 made by Mobil Exxon Chemical.
• Commercially available terpene based tackifiers are Zonarez, Zonatac and Nirez from Arizona Chemical Company.
• Commercially available piperylene based tackifiers are Picotac and Hercotac available from Hercules, Inc.
• a commercially available hydrocarbon based tackifier is Escorez 5400 from ExxonMobil.
• the preferred tackifier is rosin ester, and most preferred is a glycerin ester of tall oil rosin.
• the tackifier preferably comprises from about 0.1 to about 40% by weight of the low melt base, and preferably 0.5 to 10%, and most preferably 1 to 5 %.
• adhesion promoters such as polyolefins grafted with maleic acid or maleic anhydride (MAH), both of which convert to succinic acid or succinic anhydride upon grafting to the polyolefin, can be optionally used in addition to the tackifier.
• MAH maleic acid or maleic anhydride
• the preferred incorporated MAH graft level is 10% by weight (by titration).
• ethylene-acrylic copolymers, and a combination of this with the grafted polyolefins mentioned are suitable adhesion promoters.
• Commercially available maleic anhydride grafted polyethylene are known as ASPUN resins from Dow Chemical.
• ethylene-acrylic copolymers are Bynel 2022, Bynol 21E533 and Fusabond MC 190D from DuPont, and the Escor acid terpolymers from ExxonMobil.
• the ethylene-acrylic copolymer comprises from about 1 to about 20% by weight based on the weight of the low melt base, and preferably from 5 to 15% by weight.
• the amount of grafted polyolefin adhesion promoter is such that the weight of incorporated maleic acid or maleic anhydride comprises from about 0.05% to about 2% by weight, and preferably from 0.1 to 1.5% based on the weight of the low melt base.
• Enhancement agents can be optionally used in addition to the tackifier and the optional adhesion promoter.
• the enhancement agent can comprise any of titanium dioxide, talc, silica, alum, calcium carbonate, calcium oxide, magnesium and other oxides; titanium dioxide being preferred.
• the enhancement agent is employed in the polymer in an amount from about 0.1 to about 1% based on the weight of the low melt base.
• the particle size, in order to achieve good dispersion within the polymer and good spinnability is in the range of about 0.04 to about 5 microns, and preferably in the range of 0.05 to 2 micron.
• the low melt base with tackifier and any adhesion promoter and any enhancement agent is produced, preferably by blending master batches to the low melt base, it is melt spun into fiber as is known in the art.
• Webs of the present invention can be made by either dry laid or wet laid processes. Dry laid webs are made by the airlay, carding, garneting, or random carding processes. Airlaid webs are created by introducing the fibers into an air current, which uniformly mixes the fibers and then deposits them on a screen surface. The carding process separates tufts into individual fibers by combing or raking the fibers into a parallel alignment. Garneting is similar to carding in that the fibers are combed. Thereafter the combed fibers are interlocked to form a web. Multiple webs can be overlapped to build up a desired weight. Random carding uses centrifugal force to throw fibers into aweb with random orientation of the fibers. Again multilayers can be created to obtain the desired web weight. The dry laid components are then bonded together. Wet laid webs are made by a modified papermaking process in which the fibers are suspended in water, decanted on a screen, dried and bonded together.
• the webs are bonded by a binding fiber such as low melt polymer fiber or bicomponent fiber as noted above.
• the web of fibers can be bonded together by thermal means. Thermal bonding melts the binder fibers in an oven (hot air, radiant or microwave), or heated calendar roll(s), or by ultrasonic energy. Next, the web is cooled thereby solidifying the melted binder fiber.
• the web now has sufficient rigid structure to be useful as a component of an absorbent pad.
• the webs are made by merely mixing the binder fiber (either the low melt polymer fiber or bicomponent fiber, or both) with the absorbent fibers (with or without SAP) using dry laid or wet laid techniques.
• the absorbent is mixed with the binder fiber such that the binder fiber comprises from about 5 to about 25 percent by weight of the total web, with the remainder being substantially the absorbent.
• the web compositions of the present invention can be layered until their weight is in the range from about 20 to about 500 grams per square meter (gsm), preferably from about 50 to about 250 gsm.
• the web may be cut into various lengths and widths for end use applications, namely, fenestration drapes, dental bibs, eye pads, diapers, incontinent pads, sanitary napkins, wound dressing pads, air filters, liquid filters and fabrics such as drapes, bedding or pillows.
• the dry strength of the web was measured according to TAPPItest method T 498 om-88.
• the web strength was tested on a 25.4x 203.2 millimeter strip for both the MD (machine direction) and CD (cross direction) with an Instron 1122 test machine. The tests were run at 127 mm original separation at a speed of 304.8 mm per minute. The strength is reported in units of g/25 mm.
• Bonding Index is the square root of the product of the machine direction and cross direction strengths.
• the dust test used a 127 x 127 mm section of the web, cut into 25.4 x 25.4 mm samples. The samples were put into a Fluff Fiberization machine. An air stream with 100 PSI was applied to the samples for 300 seconds. The loosed fiber (dust) was collected with a filter. The percent of weight lost was reported as the percent of dust.
• bicomponent fibers were made with a core of 0.55 IV PET and a sheath of various compositions.
• the bicomponent fibers comprised a 50/50 core/sheath with the sheath being mainly LLDPE.
• the LLDPE was obtained from Dow Chemical Company as Aspun XU 61800.34 (Dow 34), which contains 10% by weight incorporated MAH.
• Additives (tackifier, adhesion promoter and enhancement agent) in a preblend were mixed with the sheath polymer prior to fiber spinning. The tackifier was preblended with 40% concentrate of the sheath polymer.
• the bicomponent fibers, after being spun and drawn, were cut into 6mm lengths.
• the webs comprised 12% bicomponent fiber by weight and 88% wood pulp.
• the pulp type employed was Waco 416.
• the percentage of tackifier, adhesion promoter, and enhancement agent used in the Examples (and set forth in the Tables) are based on the weight of the low melt base.
• the adhesion promoters were maleic anhydride grafted polyethylene obtained from Dow Chemical as ASPUN XU 60769.07 (Dow07), ethylene-acrylic copolymers obtained from DuPont as BYNEL 2022 and from ExxonMobil as ESCOR AT-325.
• the tackifier was a glycerin ester of tall oil rosin obtained from Eastman Chemical as PERMLYN 2085.
• Nonwoven webs were made from these bicomponent fibers with a wet-lay process to give a basis weight of 51 g/m 2 .
• the web samples were dried at 100° C for 32 seconds and then bonded in a hot air oven at 135° C for 15 seconds.
• the bonding indices are shown in Table 1, and compared to the control which did not contain a tackifier.
• Fiber Adhesion Promoter % Tackifier, % Bonding Temp., C Bonding Index, g/25 mm Relative to Control, % Control Dow 07, 10% None 135 250.9 1 Bynel 2022, 5% Permalyn, 5% 135 368.9 47.0 2 Escor AT 325, 5% Permalyn, 5% 135 285.4 13.8 3 Dow 07, 5% Permalyn, 5% 135 388.1 54.7 4 Escor AT 325, 8% Permalyn, 2% 135 281.1 12.0
• This example shows the improved tensile strength using a tackifier and adhesion promoter.
• wet laid webs were prepared in the same manner as in Example 1, and examined the effect on adhesion promoter and tackifier levels on web strength.
• the bicomponent compositions and bonding indices are reported in Table 2.
• the control was a sheath that contained no adhesion promoter or tackifier.
• This example shows that a tackifier alone, without an adhesion promoter, improves the bonding index of the web.
• Bicomponent fibers were prepared as in Example 1. These fibers were air laid with the wood pulp to give webs with a basis weight of 175 g/m 2 . The web passed through a dryer with 15 seconds residence time at 140 or 175° C. The bicomponent compositions and bonding indices are reported in Table 4. The control was a sheath that contained 10 % Dow 07 adhesion promoter. In this example an enhancement agent, TiO2, was used. The TiO2 was preblended with the sheath polyethylene (Dow 34) at a 35% concentration.
• the enhancement agent improved the bonding index.
• the tackifier with enhancement agent reduced the dust formation.

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