MXPA01001197A - Bicomponent nonwoven webs containing adhesive and a third component - Google Patents

Abstract

An improved nonwoven web composite is formed by combining bicomponent thermoplastic filaments having adhesive properties with a component selected from other fibers and particles. The bicomponent filaments include distinct regions of first and second incompatible polymers across a cross-section of individual filaments. After the bicomponent filaments are combined with the other fibers and/or particles, the adhesive properties of the bicomponent filaments result in a web or matrix of filaments having improved ability to entrap, ensnare and contain the other fibers and/or particles within the web or matrix. The nonwoven web composite is particularly useful for making absorbent articles, which require stability and optimum levels of absorbent fibers and/or particles.

Description

NON-WOVEN BICOMPONENT FABRICS CONTAINING ADHESIVE AND A THIRD COMPONENT Field of the Invention This invention relates to improved coherence nonwoven fabric composites which exhibit a combination of excellent durability, absorbency and / or other desirable properties. More specifically, the invention is directed to non-woven fabric composites containing a bicomponent filament mill having adhesive properties, and a third component selected from fibers and particles contained within the matrix.

Background of the Invention Non-woven bicomponent filaments are known in the art generally as thermoplastic filaments which employ at least two different polymers combined together in a heterogeneous form. Instead of being homogeneously mixed, two polymers can, for example, be combined in a side-by-side configuration, so that a first side of a filament is composed of a first polymer "A" and a second side of the filament is composed of a second polymer "B". Alternatively, the polymers can be combined in a sheath-core configuration, so that an outer sheath layer of a filament is composed of a first polymer "A" and the inner core is composed of a second polymer "B". Alternatively, the polymers may be combined in an island configuration at sea in which one or more of the islands of a first polymer "A" appear in a sea of a second polymer "B". Other heterogeneous configurations are also possible.

The bicomponent filaments offer a combination of desired properties. For example, certain polypropylene resins give filaments which are strong but not particularly soft. Certain polyethylene resins give filaments which are soft but not particularly strong. By combining both resins together in the form of bicomponent non-woven filaments, a hybrid combination of strength and softness can be achieved.

The bicomponent filaments have been described in combination with carbon particles, zeolites, resins of ion exchange, carbon filters, sterilizing fibers, and / or gas absorbent fibers for use in specialized filters. U.S. Patent No. 5,670,044 issued to Ogata et al. Describes the use of blown filaments with bicomponent melting in these combinations, for to be used in cylindrical filters. In that case, the bicomponent filaments contain high and low melt polymers. The , »-» ". ¿¿Saám *, ixz..r 'rz r ^ ... & > * u * - ^^^ _, .. ,, ^. ^ Filter filaments are stacked and united together by melting only the lowest melted component.

Pulp fibers have been used in certain absorbent applications to improve absorbency. U.S. Patent No. 4,530,353 issued to Lauritzen, describes pulp fibers in combination with basic length bicomponent fibrcis used in the manufacture of absorbent bandages. In this case, the fibers also contain high melting and low melting polymers. The fibers of basic length are joined together by melting only the lowest melted component.

In applications where a third component As selected from fibers and / or particles is combined with a two-component filament yarn, the bicomponent filaments act as a matrix which it catches in a trap, traps and contains the third component. In some of these applications (for example absorbent applications where the third The component is an absorbent) there is a need or desire to increase the amount of the third component in order to maximize the properties that it contributes to the non-woven fabric composite. There is also a need or desire to improve the containment properties of the bicomponent filament matrix in all the load levels of the third component. \ l .- &.; ^^,. ^ IIÍ - faith; "_" -: T | ff-f Synthesis of the Invention The present invention is directed to an improved nonwoven fabric composite that includes a bicomponent thermoplastic filament matrix and a third component selected from fibers, particles, and combinations thereof contained within the filaments. The non-woven fabric composite exhibits improved containment of the third component, which allows superior loading of the third component as well as improved durability at all load levels. The present invention is also directed to an absorbent article, which includes an absorbent article for personal care, which utilizes the improved nonwoven fabric composition of the invention.

The bicomponent thermoplastic filaments contain at least the first and second thermoplastic polymer components, arranged in different segments or zones across the width of the filament. At least one of the thermoplastic polymers possesses adhesive properties with respect to the third component, or is modified to possess adhesive properties with respect to the third component. The adhesive properties can be imparted by either a) the use of an adhesive polymer for at least one of the different thermoplastic polymer segments in the bicomponent filaments, whose segment is exposed to the filament surface, b) by modifying the a non-adhesive polymer to - *, by mixing it with an adhesive polymer and using the mixture for one of the different polymer segments in the bicomponent filaments, whose segment is exposed on the surface of the filament, or c) by modifying the surface of the bicomponent filaments or a segment thereof by means of spraying, embedding, or by means of otherwise applying an effective adhesive material for joining the bicomponent filaments to the third component.

With the foregoing in mind, a feature and advantage of the invention is to provide a non-woven fabric composite containing a filament matrix and a charged component (fibers and / or particles) within the matrix, which has a durability and Improved stability due to adhesion between the filament matrix and the charged component.

It is also a feature and an advantage of the invention to provide an absorbent nonwoven fabric composite capable of containing high loads of fibers and / or absorbent particles, due to the adhesion between the absorbent material and the thermoplastic nonwoven filament matrix that contains It is also a feature and an advantage of the invention to provide an absorbent article having an improved absorption and durability, due to the better containment of the fibers and / or absorbent particles within a non-woven filament matrix, and a higher loading capacity for the fibers and / or absorbent particles.

Definitions The term "nonwoven fabric or fabric" means a fabric having a structure of individual fibers or threads which are interposed, but not in an identifiable manner as in a woven fabric. Non-woven fabrics or fabrics have been formed by many processes such as, for example, meltblowing processes, spin-bonding processes, and air laying processes, and carded and bonded tissue processes. . The basis weight of non-woven fabrics is usually expressed in ounces of material per square yard (osy) or in grams per square meter (gsm) and useful fiber diameters are usually expressed in microns. (Note that to convert from ounces per square yard to grams per square meter, multiply ounces per square yard by 33, 91).

As used herein, the term "microfibers" means small diameter fibers having an average diameter of no more than about 75 microns, for example, having an average diameter of from about 1 micron to about 50 microns, or more particularly , who have a average diameter from about 1 miera to around 30 micras. Another frequently used expression of fiber diameter is denier, which is defined as grams per S, 000 meters of a fiber. For a fiber having a circular cross section 5, the denier can be calculated as fiber diameter in square microns, multiplied by the density in grams / cc, multiplied by 0.00707. A lower denier irdicates a finer fiber and a higher denier indicates a thicker or heavier fiber. For example, the diameter of a fiber of polypropylene given as 15 microns can be converted to denier by placing the square, multiply the result by, 89 g / cc and multiply by, 00707. Thus, a polypropylene fiber of 15 microns has a denier of about 1.42 (152 x 0.89 x, 00707 = 1.415). Outside the United States of America the unit of measurement is most commonly the "tex" which was defined as grams per kilometer of fiber. The tex can be calculated as denier / 9.

"Spunbonded fibers" refer to 20 small diameter fibers which are formed by extruding the melted thermoplastic material as filaments from a plurality of fine capillary vessels of a spinner having a circular or other configuration, with the diameter of the extruded filaments then being rapidly reduced as, for example, in the United States Patents of America Nos. 4,340,563 issued to Appel et al., and the patent of the United States of America number 3,692,618 issued to Dorschner et al., United States of America patent number 3,802,817 issued to Matsuki et al., United States of America No. 3,338,992 and 3,341,394 patents issued to the United States of America. Kinney, patents of the United States of America numbers 3,502,763 granted to Hartman, 3,502,538 granted to Petersen, and 3,542,615 granted to Dobo and others, each of which is hereby incorporated in its entirety by reference. The yarn-bound fibers are cooled and deposited on a collecting surface. Spunbonded fibers are generally continuous and often have longer average diameters of about 7 microns, more particularly between about 10 and 30 microns.

The term "meltblown fibers" means fibers formed by extruding a melted thermoplastic material through a plurality of thin, usually circular, capillaries, like melted threads or filaments into gas streams (eg, air) heated to high speed and convergent which attenuate the filaments of melted thermoplastic material to reduce its diameter, which can be a microfiber diameter. Then, the meltblown fibers are carried by the high velocity gas stream and are deposited on a collector surface to form a randomly dispersed meltblown fabric. Such a process is described, for example, in the patent of United States of America number 3,849,241 granted to Butin. The melt blown fibers are microfibers which may be continuous or discontinuous, are generally smaller than 10 microns in diameter, and are generally self-bonding when deposited on a collecting surface. The meltblown fibers used in the present invention are preferably and essentially of continuous length.

The term "fiber filaments essentially "Continuous" refers to filaments or fibers prepared by extrusion from a spinning organ, including without limitation spunbond and meltblown fibers, which are not cut from their original length before being formed into a non-woven or non-woven fabric. woven, the filaments or fibers essentially Continuous lengths may have average lengths ranging from more than about 15 centimeters to more than 1 meter, and up to the length of the nonwoven fabric or fabric that is being formed. The definition of "essentially continuous filaments or fibers" includes those which are not cut before they are formed into a nonwoven fabric or fabric, but which are subsequently cut when the fabric or the non-woven fabric is cut.

The term "basic fibers" means fibers which are natural or cut from a filament manufactured before of the formation in a fabric, and which have a length ... ^ v .--- K -_ ^ - »-» h ^ _ .. as «--r-l-r-fl. _-. j-k. - _.- a average that varies from about 0.1-15 centimeters, more commonly around 0.2-7 centimeters.

The term "pulp fibers" refers to fibers from natural sources such as woody and non-woody plants. Woody plants include, for example, deciduous and coniferous trees. Non-woody plants include, for example, cotton, flax, esparto grass, benzene, straw, hemp and bagasse.

The term "average pulp fiber length" refers to a length of average heavy pulp determined using a Kajaani Fiber Analyzer Model No. FS-100 available from Kajaani Oy Electronics of Kajaani, Finland. Under the test procedure, a sample of fiber is treated with a macerating liquid to ensure that no fiber chips or handles are present. Each fiber sample is dispersed in hot water and diluted to around a concentration of 0.001%. The individual test samples are pulled in portions of approximately 50 to 500 ml of the diluted solution and tested using the normal Kajaani fiber analysis procedure. The average heavy fiber lengths can be expressed by the following equation: k S (X, 'nj / n X.> 0 ggg ..- _. ^ & ^. ^^^^^ g ^. where k = maximum fiber length X. = length # te individual fiber n. = number of fibers that have the length X. and n = total number of fibers measured. The term "superabsorbent material" refers to an organic or inorganic material insoluble in water and water-swellable which is capable, under the most favorable conditions, of absorbing at least 20 times its weight, preferably at least about 30 times its weight. times its weight in an aqueous solution containing 0.9% by weight of sodium chloride.

The term "polymer" generally includes, without limitation, homopolymers, copolymers (including, For example, block, graft, random and alternating copolymers), terpolymers, etc., and mixtures and modifications thereof. In addition, unless specifically limited in another way, the term "polymer" will include all possible geometric configurations of the material. 20 These configurations include, but are not limited to, isotactic, syndiotactic and atactic symmetries.

The term "bicomponent filaments or fibers" refers to fibers which have been formed of at least two polymers extruded from separate extruders but spun together to form a fiber. The polymers are arranged in zones different parts placed essentially constant across the cross section of the bicomponent fibers and extend continuously along the length of the bicomponent fibers. The configuration of such bicomponent fiber 5 can be, for example, a pod / core arrangement where one polymer is surrounded by another, or it can be a side-by-side arrangement or an arrangement of "islands in the sea". The bicomponent fibers are taught in U.S. Patent Nos. 5,108,820 issued to Kaneko et al., 5,336,552 issued to Strack et al., And 5,382,400 issued to Pike et al., Each of the which are incorporated here in their totality by this reference. For the two component fibers, the polymers may be present in proportions of 75/25, 50/50, 25/75 or any other desired proportions. Conventional additives such as pigments and surfactants can be incorporated into one or more polymer streams, or applied to the filament surfaces.

The terms "adhesive polymer", "adhesive polymer blend" and "adhesive filament" refers to any polymer, polymer or filament mixture containing it and exhibiting a strength of adhesiveness to a third component of fiber or particle, without import how small. This includes any kind of adhesion or stickiness. If a fiber or particle exhibits a binding strength or a reluctance to separate from a thermoplastic polymer filament when the ____-_? < - »- & __ £« - _ * _- E-_. .-- ^^ ---- filament is placed on one side of the fiber or particle and the fiber or particle is subjected to a gravitational pull or another or a sliding force, then at least one polymer in the filament exhibits a force of adhesion (eg adhesive) to the fiber or particle.

The terms "adhesive-modified polymer", "adhesive-modified polymer mixture" and "adhesive-modified filament" refer to a polymer, a polymer mixture or a filament containing them which has been modified (through the surface coating, mixing or otherwise) so that it exhibits an adhesive force to a fiber or particle, as defined above.

The term "bicomponent filaments having adhesive properties" refers to any bicomponent adhesive filament as well as to any bicomponent filament modified with adhesive.

The term "absorbent article for personal care" includes diapers, underpants, swimwear, absorbent underwear, baby wipes, adult incontinence products and women's hygiene products.

The term "air binding" or " " means a process of joining a nonwoven, for example, a two-component fiber fabric in which air that is hot enough to melt One of the polymers from which the fibers of the fabric are made is forced through the fabric.The air speed is frequently between 100 and 500 feet per minute and the dwell time can be as long as 6 seconds. and the resolidification of the polymer provide the binding.The union through air has a restricted variability and is generally seen as a second step joining process.The binding through air requires the melting of at least one component for to achieve the union, this is restricted to fabrics with two components such as the fabrics of bicomponent fibers or the tissues that contain a fiber or adhesive powder.

The term "thermal point union" involves passing a fabric or fabric of fibers to be joined between a heated calender roll and an anvil roll. The calendering roller usually has, although not always, a pattern in some way so that the entire fabric is not bonded through its entire surface. As a result of this, various patterns for calendering rolls have been developed for functional as well as aesthetic reasons. An example of a pattern has points and is the pattern Hansen Pennings --_-_. * r_f? Í-? tÉr ¥ ~ * '* - * - * - * - A »_- __ £ or" H &P "with around a 30% bound area with about 200 joints / square inch as taught in the patent of: United States of America No. 3,855,046 issued to Hansen and Pennings. The Hansen and Pennings pattern has 5-bolt or square-dot joint areas where each bolt has a 0.038-inch (0.965-millimeter) lateral dimmer, a 0.070-inch (1.778-millimeter) gap between the bolts, and a joint depth of 0.023 inches (0.584 millimeters). The resulting pattern has a bound area of about 29.5%.

Another typical point union pattern is the Hansen and expanded Pennings junction pattern or "EHP" which produces a 15% bound area with a square bolt having a side dimension of 0.037 inches (0.94 millimeters), a bolt spacing of 0.097 inches (2.464 millimeters) and a depth of 0.039 inches (0.991 millimeters). Another typical point union pattern designated "714" has square bolt joint areas where each bolt has a side dimension of 0.023 inches, a spacing of 0.062 inches (1.575 mm) between the bolts, and a joint depth of 0.033 inches (from 0.838 mm). The resulting pattern has a unit area of around 15%. Yet another common pattern is the star-C pattern which has a bound area of about 16.9%. The star-C pattern has a bar design in the transverse direction or "corduroy" interrupted by shooting stars.

Other common patterns include a diamond pattern with slightly off-center and repetitive diamonds and a pattern of woven wire that looks like the name suggests, for example as a window grid. Typically, the area of bond area varies from about 10% to about 30% of the area of the fabric of the fabric laminate. As is well known in the art, the knit joint holds together the layers of the laminate as well as the one imparting integrity to each individual layer by joining the filaments and / or the fibers within each layer.

Detailed Description of Current Preferred Incorporations The present invention is directed to a non-woven fabric composite that includes a matrix of filaments of Two-component thermoplastic polymer having adhesive properties, namely, including adhesive filaments and / or adhesive-modified filaments. The matrix may optionally contain non-adhesive thermoplastic filaments (bicomponent or single component) with the adhesive filaments.

A third selected component of fibers, particles and combinations thereof is contained within the filaments. The non-woven fabric composite contains from about 5-97% by weight of the third component (fibers, particles or combinations thereof) and about 2-95% by weight of the adhesive and / or the bicomponent thermoplastic filaments modified with adhesive. Preferably, the -__________ composed of non-woven fabric contains about 35-95% by weight of the third component and ajy kb dedor of 5-65% by weight of the bicomponent adhesive filaments. More preferably, the non-woven fabric composite contains about 50-95% by weight of the third component and about 5-50% by weight of the thermoplastic bicomponent filaments having adhesive properties.

The bicomponent thermoplastic filaments having adhesive properties may have any of the bicomponent configurations described above. Preferably, the filaments have either a side-by-side configuration or a sheath and core configuration. In these configurations, the polymers within the filaments extend to the length of the filaments. The bicomponent filaments are preferably and essentially continuous in length. The essentially continuous filaments provide better containment of the third component and a better distribution of the liquid than the fibers of basic length. The bicomponent filaments may be spunbond or meltblown, for example, and may have an average dreary of from about 1-75 microns, preferably from about 1-50 microns, more preferably from about 1-30 microns. . Other processes for forming the thermoplastic bicomponent filaments can also be employed. The g ^^^^^^ _ ^^^^ -_ ^^^^^^^^^ jj ^ filaments can be curled, using the techniques available to those skilled in the art.

The bicomponent filaments that have adhesive properties contain at least two thermoplastic polymers. In one embodiment, the filaments! Two-component thermoplastics contain a first polymer (or a mixture of polymers) which imparts a desirable first property to the filaments, and a second polymer (or mixture of polymers) which imparts adhesive properties to the filaments. In another embodiment, the thermoplastic bicomponent filaments contain a first polymer (or a mixture of polymers) which imparts a desirable first property, a second polymer (or polymer blend) which imparts a desirable second property, and an adhesive modifier (for example a surface treatment) which imparts adhesive properties to the filaments. Examples of the desirable properties attributable to the different polyrrhers or mixtures include, without limitation, durability, softness, wetting, elasticity, resistance, stability, aesthetic appearance and other desirable properties. Of course, the first polymer may contribute one or more desirable properties, and the second polymer may contribute to the adhesion and / or one or more additional desirable properties. Also, the bicomponent filaments may include more than two different polymers, with each polymer contributing to unique properties. Adiffeners, such as pigments and hydrophilic modifiers, can be incorporated into one or both polymers, or applied to the surfaces of the filament.

Examples of polymer components which contribute to the life of bicomponent filament fabrics include without limitation polypropylene homopolymers, polypropylene copolymers containing up to about 10% ethylene or another C4-C20 alpha olefin comonomer, high density polyethylenes, linear low density polyethylene in which the alpha olefin comonomer content is less than about 10% by weight, polyamides, polycarbonate polyesters, polytetrafluoroethylenes, and other high-tensile materials. Generally, a first polymer can be said to contribute to the duration of the bicomponent filaments when a nonwoven fabric made of bicomponent filaments containing a first polymer and a second polymer supports a stress load which is at least about 10% larger, and preferably at least about 30% larger, than a similar nonwoven fabric made of similar filaments containing the second polymer alone.

Examples of polymer components which contribute to flexibility and softness for bicomponent filament fabrics include without limitation the low-density polyethylenes ^^^ aminated) and high-pressure polyethylenes of linear low density in which the alpha olefin comonomer content is more than about 10% by weight, the copolymers of ethylene with at least one monomer of vinyl (for example ethylene vinyl acetate), the copolymers of ethylene with unsaturated aliphatic carboxylic acids (including the ester derivatives thereof) and the copolymers of any two alpha-olefins having 2-20 carbon atoms wherein the content of each of the; two comonomers exceeds 10% by weight of the copolymer (including, for example, ethylene-propylene rubbers). Also included are polyurethanes and block copolymers A-B and A-B-A 'wherein A and A' are thermoplastic end blocks and B is an elastomeric block. Generally, a second polymer can be said to contribute to the flexibility and / or softness for a two-component non-woven fabric when making a non-woven fabric from the filaments containing a first polymer and the second polymer is more flexible, and / or has a softer feel, than a similar non-woven fabric made of similar filaments that contain only the first polymer.

Examples of polymers shawls contribute to wettability for a non-woven thermoplastic fabric include without limitation polyamides, polyvinyl acetates, saponified polyvinyl acetates, saponified ethylene vinyl acetates, and other materials hydrophilic A second polymer generally contributes to the wettability of the bicomponent filaments if a drop of water placed on a nonwoven fabric made of bicomponent filaments containing the first and second polymers has a contact angle which is a) less than 90 ° measured using ASTM D724-89; and b) smaller than the contact angle of a similar nonwoven fabric made of similar filaments containing only the first polymer.

Examples of the polymers which contribute elastic properties to the thermoplastic non-woven fabric include without limitation the styrene-butadiene copolymers; elastomeric polypropylene (for example, single site, eg, metallocene catalyzed), polyethylene, and other catalyzed alpha olefin homopolymers and copolymers; with metallocene having a lower density of about 0.89 grams / cc; other amorphous polyalpha olefins having a lower density of about 0.89 grams / cc; ethylene vinyl acetate copolymers; ethylene propylene rubbers; and propylene-butene-1 copolymers and terpolymers. The elastomeric polymers can help facilitate the curling of the bicomponent filaments as discussed later in the description.

The examples of the polymers which contribute with adhesion to the bicomponent filaments (for ^ ¿_ _ _ _ _ _ $ _-. ^ ---- te ^ - ----- »? ÍS __- T X & ? X -? -, -.-"eg adhesive polymers) may vary depending on the substrate of the third compliant to which adhesion is desired. Polymers which adhere to a third component substrate may not adhere to each other. Examples of effective adhesive polymers for a variety of substrates include, without limitation, polyolefin waxes, for example polyethylene waxes and polypropylene waxes; amorphous polyethylenes and polypropylenes; the copolymers of ethylene propylene and butene propylene containing more than 10% of each comonomer, the terpolymers of ethylene, propylene and butene; the styrene-butadiene block copolymers, glutinizing and rubber; ethylene vinyl acetate copolymers containing more than 5% by weight of vinyl acetate; ethylene alkyl acrylates, including ethylene methyl acrylate, ethylene ethyl acrylate and ethylene-n-butyl acrylate; poly (4-methyl-1-pentene); various polymers and alpha olefin copolymers in which at least one alpha olefin comonomer has 4-20 carbon atoms; resins and hydrocarbon glutinizantes; thermofused adhesives formulated; combinations including the above; and several other materials.

Of course, the ability of the polymers to contribute to the adhesion and other desired properties for non-woven bicomponent filaments requires that there be a sufficient amount of each polymer in the filaments. Generally, bicomponent thermoplastic filaments contain about 10-90% by weight of the first polymer ^ M ^ ^^^^ S ^ g ^ ^ j selected and about by weight of the second selected polymer. The bicomponent filaments will preferably include about 25-75% by weight of each polymer, more preferably about 40-60% by weight of each polymer.

The adhesive properties can be imparted alternatively to the bicomponent filaments by initially forming the bicomponent filaments using the non-adhesive polymers, and then coating the surface of the filaments with an adhesive polymer. For example, an adhesive polymer can be dissolved in solution and applied by spraying, brushing, embedding, printing or other solution techniques. Alternatively, an adhesive polymer can be applied by hot melt techniques, for example, by melt blowing, melt spraying or melt printing. The resultant bicomponent filaments modified with adhesive can then be combined with the third component. Alternatively, the adhesive coating may occur after the bicomponent filaments are combined with a third component.

A wide variety of fibers and / or third component particles can be incorporated into the matrix of bicomponent filaments having adhesive properties, to make the nonwoven fabric composite of the invention have • a _- «-« - tea-B ^ fca ----, ^ _. ^. "A-." V *. Or .. -'- improved durability and containment properties Fibers which may be employed as the third component include, without limitation, absorbent fibers such as basic rayon fibers. , the cotton fibers, the short length natural cellulose fibers such as wood pulp fibers and cotton lint, other pulp fibers, superabsorbents which are in the form of fibers and combinations of the above .

Other useful fibers include fibrillated feathers; for example, the feathers of fibrillated birds such as fibrillated chicken feathers. The particles can be used as the third component alone or in combination with the fibers. Examples of useful particulate materials include, but are not limited to activated charcoal, clays, starches, superabsorbents in the particulate form and odor absorbers such as zeolitae, cassava chitosan and molecular sieve materials.

The thermoplastic bicompound nonwoven filaments can be combined with the third component materials using processes well known in the art. For example, a coform process may be employed, in which at least one die head is arranged near a conduit to through which other materials are added while the fabric is being formed. The coform processes are described in US Patents of US Nos. 4,818,464 to Lau and 4,100,324 to Anderson et al., whose descriptions are incorporated by reference. Thermoplastic bicomponent filaments and third component materials can also be combined using hydraulic entanglement or mechanical entanglement. A hydraulic entanglement process is described in U.S. Patent No. 3,485,706 issued to Evans, the description of which is incorporated by reference.

The pulp fibers are especially useful as the third component when the composite nonwoven fabric is employed as an absorbent article. Preferred pulp fibers include cellulose pulp fibers. The pulp fibers can be any high average fiber length pulp, low average fiber length pulp, or mixtures thereof.

The term "high average fiber length pulp" refers to a pulp that contains a relatively small amount of short fibers and particles that are not fibers. The high fiber length pulps typically have an average fiber length greater than about 1.5 millimeters, preferably about 1.5-6 millimeters, as determined by a fiber optic analyzer, such as a Kajaani tester mentioned above. The sources generally __...---. * ___.-_ * .._-_ .-- __-,, _? ____ - _ M -_-- ^ t .__ g ^ _ * _ «_- ,. ..; .-. they include the non-dried fibers (virgins) as well as the secondary fiber pulp which has been screened. Examples of: high average fiber length pulps include pulps of virgin softwood bleached and unbleached.

The term "low average fiber length pulp" refers to a pulp that contains a significant amount of short fibers and non-fiber particles. The low average fiber length pulps have an average fiber length of less than about 1.5 millimeters, preferably about 0.7-1.2 millimeters as determined by a fiber optic analyzer such as the tester Kajaani that has been mentioned above. Examples of low average fiber length pulps include virgin hardwood pulp, as well as secondary fiber pulp from sources such as office waste, newsprint and cardboard pieces.

Examples of high average fiber length wood pulps include those available from U.S. Alliance Coosa Pines Corporation, under the Longlac 19, Coosa River 56 and Coosa River 57 trade designations. Low average fiber length pulps may include some virgin hardwood pulp and secondary fiber pulp (eg recycled) from sources including newspaper, reclaimed cardboard and office waste. Mixtures of pulp length J-J ------- ^. -, ^ lfc_.

High average fiber and low average fiber length may contain a predominance of low average fiber length pulps. For example, blends can contain more than about 50% by weight of pulp of low average fiber length and less than about 50% by weight of high average length of fiber pulp. An example mixture contains about 75% by weight of pulp of low average fiber length and about 25% by weight of pulp of high average fiber length. 10 Pulp fibers may not be refined or may be struck at varying degrees of refinement. The cross-linking agents and / or the moisturizing agents can also be added to the pulp mixture. The age --tes Disunders can also be added to reduce the degree of hydrogen bonding if a loose or very open nonwoven pulp fiber fabric is desired. An exempting exemplary agent is available from Quaker Oats Chemical Company, of Conshohocken, Pennsylvania, under the trade designation Quaker 2208.

The addition of certain binder agents in the amount of, for example, 1-4% by weight of the compound can reduce the measured static and the dynamic coefficients of friction and improve the abrasion resistance of the thermoplastic continuous polymer filaments. Deagglutinating agents act as lubricants or friction reducers. The pulp fibers > t- jdj __ »_.--. Fc-.t- - faith-_a- £ -___- ^^^ ^. , »--- -. __. . , - - 'Deagglutinates are commercially available from Weyerhaeuser Corporation under the designation NB405.

In a highly advantageous embodiment, the third component includes a combination of pulp fibers and superabsorbent particles and / or fibers, resulting in the formation of a highly absorbent nonwoven fabric composite. The term "superabsorbent" or "superabsorbent material" refers to an organic or inorganic material insoluble in water and swellable in water capable, under the most favorable conditions, of absorbing at least about 20 times its weight and, more desirably, by at least about 30 times its weight in an aqueous solution containing 0.9% by weight of sodium chloride.

The superabsorbent materials can be polymers and natural, synthetic and modified natural materials. In addition, the superabsorbent materials may be inorganic materials, such as silica gels or organic compounds such as crosslinked polymers. The term "crosslinked" refers to any means for effectively making the materials normally water-soluble essentially insoluble but swellable in water. Such means may include, for example, physical entanglement, crystalline domains, covalent bonds, complexes and ionic associations, hydrophilic associations, such as hydrogen bonding, and hydrophobic associations or Van der Waals forces.

Examples of the synthetic superabsorbent material polymers include the alkali metal and ammonium or poly (acrylic acid) and poly (methacrylic acid) salts, the poly (acrylamides), the poly (vinyl ethers), the maleic anhydride copolymers with vinyl ethers and alpha olefins, poly (vinyl pyrrolidone), poly (vinyl morpholinone), poly (vinyl alcohol) and mixtures and copolymers thereof. Additional superabsorbent materials include the natural and modified natural polymers, such as hydrolyzed acrylonitrile grafted starch, acrylic acid grafted starch, methyl cellulose, chitosan, carboxymethyl cellulose, hydroxypropyl cellulose, and natural gums such as alginates, xanthan gum, locust bean gum and the like. Mixtures of natural and fully or partially synthetic superabsorbent polymers may also be useful in the present invention. Other suitable absorbent gelation materials are described by Assarsson et al. In U.S. Patent No. 3,901,236, issued Aug. 26, 1975. Processes for preparing synthetic absorbent gelation polymers are described in the patents of the United States of America Nos. 4,076,663 granted on February 28, 1978 to Masuda and others and 4,286,082 granted on August 25, 1981 to Tsubakimoto et al. ^ 3 ^ _ & _M_-¡- ^ - Í & - k -f- & -M-¿- i - ^ - c - ^ -.-- X --_ < __---- ~ _x-_ ____ a -_ ^ -jÍJ > ^ ft ^ B - 1t.A ... ¿¿aég - aSAaa -. ^ »--.-. .-_.- •. .

The superabsorbent materials can be xerogels which form hydrogels when wetted. The term "hydrogel", however, has commonly been used to refer also to both wet and unmoistened forms of the superabsorbent polymer material. The superabsorbent materials may be in many forms such as flakes, powders, particles, fibers, continuous fibers, networks, fabrics and spun filaments of solution. The particles can be of any desirable shape, for example, spiral or semi spiral, cubic, rod type, polyhydric, and so on. Needles, flakes, fibers and combinations can also be used.

When used, the superabsorbent material may be present within the composite absorbent nonwoven fabric in an amount of from about 5 to about 90% by weight based on the total weight of the absorbent nonwoven composite. Preferably, the superabsorbent constitutes about 10-60% by weight of the absorbent nonwoven fabric composition, more preferably about 20-50% by weight.

The superabsorbents are generally available in particle sizes ranging from about 20 to about 1. 000 microns. Examples of commercially available particulate superabsorbents ® include the SANWET IM 3900 and SANWET IM-5000P, available from Hoechst Celanese located at ® Portsmouth, Virginia, DRYTECH 2035LD available from Dow Chemical Company located in Midland, Michigan, and FAVOR® 880 available from Stockhausen, located in Sweden. An example of a fibrous superabsorbent ® is OASIS 101, available from Technical Absorbents, located in Grimsby, United Kingdom.

The superabsorbents can be added using the same techniques described above to combine the pulp fibers and the bicomponent non-woven filaments. For example, the superabsorbent can be added with the pulp in the forming stream for the bicomponent filaments as they are extruded onto a conveyor to form a non-woven fabric, or at a later point in the forming stream, separated from the pulp. Alternatively, the superabsorbents can be added to a non-woven fabric using a hydraulic entanglement process.

After combining the ingredients, the absorbent nonwoven fabric composite can be bonded together using the thermal bond or air bonding techniques described above, to provide a coherent high integrity structure. It is considered that various improvements and alternate additions are also within the scope of the invention. In one embodiment, the bicomponent thermoplastic filaments having adhesive properties are combined with other thermoplastic filaments in addition to the puLpa fibers. For example, the two-component thermoplastic filaments that * ^ g ~ - - • • • • ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ - - They have adhesive properties that may include a mixture of filaments bonded with bicomponent yarn and blown filaments with bicomponent melting. In this embodiment, the spunbonded filaments impart greater strength and the meltblown filaments are more effective in capturing and entangling the fibers and / or particles of the third component. Also, bicomponent filaments having adhesive properties can be combined with non-adhesive filaments (bicomponent or single component). In yet another embodiment, the bicomponent filaments having adhesive properties can be spun bonded and blended with the meltblown fibers (not necessarily bicomponent) which have a point of melted relatively low. The composite fabric can therefore be formed by combining three or more streams of filaments attached with bicomponent yarn, blown filaments with lower melt melt and pulp fibers. The meltblown filaments may still be hot and sticky when the particles and / or fibers of the third component are introduced, and can be fused with the third component to help consolidate the structure. Meltblown microfibers, which typically have much smaller diameters than those of fibers bonded with The spinning can, in effect, serve as an additional binder or adhesive for the fibers and / or particles of the third component. # * • ..-. , _i ^ .üiÉ --- i,. -.? - .., ... __É ----- fc-_J -----!, -? .... «- ---- g * ^ -.,. In another embodiment, an elastic polymer can be combined with an inelastic polymer in bicomponent filaments from side to side to produce bicomponent filaments that have a tendency to curl. The elastic polymer can also be an adhesive polymer. The resulting crimped bicomponent filaments having adhesive properties are preferably in the form of meltblown microfibers, which are relatively fine and flexible. The crimped bicomponent filaments having adhesive properties can be used with or without the thermoplastic filaments in a non-woven fabric to provide increased volume and lower tissue density. In the non-woven fabrics of the present invention, the crimped bicomponent filaments can also be used to help trap and entangle the particles and / or fibers of the third component.

Exemplary combinations of the elastic (potentially adhesive) and inelastic materials useful for producing the crimped bicomponent filaments having adhesive properties include, without limitation, the following: ü jfc ^ 10 fifteen Notes 1. Unless otherwise indicated, polymers are not made using the metallocene catalyst. 2. Unless indicated otherwise, polypropylene polymers are essentially isotactic.

In addition to elastic polymer combinations and inelastic, other polymer combinations can be used to achieve curling. For example, curling can be achieved by using combinations of heat-shrinkable polymers (polymers whose filaments shrink with secondary heating at a temperature below melting temperature). peak) without polymers non-heat shrinkable in essentially continuous bicomponent thermoplastic filaments. Given the Many heat-shrinkable polymers are not adhesive, the filaments must be modified using the techniques described above to impart the adhesive properties. Example combinations of heat-shrinkable and non-heat shrinkable polymers include without limitation the following: Certain other polymer combinations also result in shrinkage, when they extend side by side in an essentially continuous thermoplastic bicomponent filament. These combinations include without limitation the following: The improved nonwoven composite material of the invention can be used in a wide variety of absorbent and other products including, but not limited to, absorbent articles for personal care. Absorbent personal care items include diapers, underpants, swimwear, absorbent underwear, baby wipes, adult incontinence products, women's hygiene products and the like . The improved nonwoven composite is particularly useful in diapers, baby wipes, and other applications that require durability, and a high load and retention of the third component. In these applications the third component can, for example, include a combination of pulp fibers and superabsorbent. The nonwoven composite material of this invention can also be used in a wide variety of other absorbent and non-absorbent applications including, without limitation, medical absorbent products; such as lower pads, bandages, absorbent covers, and medical wipes that contain alcohol and / or other disinfectants.

Although the embodiments of the invention described herein are presently preferred, various modifications and improvements may be made without departing from the spirit and scope of the invention. The scope of the invention is indicated by the appended claims, and all changes within the meaning and range of equivalents are intended to be encompassed therein.

Claims (52)

R E I V I N D, BC A C I O N E S

1. A composite of non-woven fabric that purchases: a matrix of essentially continuous thermoplastic bicomponent filaments having adhesive properties, including a first thermoplastic polymer and a second thermoplastic polymer arranged in different zones through a cross section of the individual bicomponent filaments; Y a third absorbent component contained within the matrix, the third component is selected from the group consisting of absorbent fibers, absorbent particles and combinations thereof; wherein the adhesive properties of the bicomponent filaments facilitate containment of the third component.

2. The non-woven fabric composite, as claimed in clause 1, further characterized in that it comprises thermoplastic filaments without adhesive properties.

3. The non-woven fabric composite, as claimed in clause 1, further characterized in that the -Afe *** ^ - * ^ *. ^ -. ^^ _-- fc ^ - ^ - ^ _ ---- ^^^ -__... - .-, .. - _, - ^ Thermoplastic bicomponent coatings comprise filaments attached with spinning.

4. The non-woven fabric composite, as claimed in clause 1, further characterized in that the thermoplastic bicomponent filaments comprise meltblown filaments.

5. The non-woven fabric composite, as claimed in clause 1, further characterized in that the thermoplastic bicomponent filaments comprise spunbonded filaments and meltblown filaments.

6. The non-woven fabric composite, as claimed in clause 1, further characterized in that the thermoplastic bicomponent filaments are arranged in a side-by-side configuration.

7. The non-woven fabric composite, as claimed in clause 1, further characterized in that the thermoplastic bicomponent filaments are arranged in a sheath and core configuration.

8. The non-woven fabric composite, as claimed in clause 1, further characterized in that the ^ -.-__--. -----...- i .. »Thermoplastic bicomponent filaments are arranged in an island configuration at sea.

9. The non-woven fabric composite, such and such, is claimed in clause 1, further characterized in that the at least one of the first and second thermoplastic polymers comprises an adhesive polymer.

10. The non-woven fabric composite, as claimed in clause 9, characterized in that the adhesive polymer comprises a material selected from the group consisting of polystyrene waxes, polypropylene waxes, amorphous polyethylenes, amorphous polypropylenes, ethylene-propylene copolymers and of butene-propylene containing more than 10% of each comonomer, terpolymers of ethylene, propylene and butene, styrene and butadiene glutinizing agents and rubbers, ethylene vinyl acetate copolymers containing more than 5% by weight of vinyl acetate, ethylene alkyl acrylates, poly (4-methyl-1-pentene), alpha-olefin polymers and copolymers in which at least one alpha olefin has 4-20 carbon atoms, resins! of hydrocarbon and glutinizers, hot melt adhesives, and combinations thereof.

11. The non-woven fabric composite, as claimed in clause 1, characterized in that the filaments ite «« tea * - '^ r "^ * -----' - ~ * i * fc- ^ - bicomponent thermoplastics comprise filaments modified with adhesive.

12. The non-woven fabric composite, as claimed in clause 1, characterized in that at least one of the first and second polymers comprises a relatively durable polymer.

13. The non-woven fabric composite, such and such, is claimed in clause 12, characterized in that the relatively durable polymer comprises a material selected from the group consisting of polypropylene homopolymers and copolymers containing up to about 10% by weight of an alpha comonomer. olefin, high density polyethylene, linear low density polyethylene having an alpha olefin comonomer content of less than about 10% by weight, polyamides, polyesters, polycarbonates, polytetrafluoroethylenes, and combinations thereof.

14. The non-woven fabric composite, as claimed in clause 1, characterized in that at least one of the first and second polymers comprises a relatively soft polymer.

15. The non-woven fabric composite, as claimed in clause 14, characterized in that the polymer Relatively soft comprises a material selected from the group consisting of branched low density polyethylene, linear low density polyethylene having an alpha-olefin comonomer content of greater than about 10% by weight, ethylene copolymers, with at least a vinyl comonomer, copolymers of ethylene with unsaturated aliphatic carboxylic acids and ester derivatives thereof, other copolymers of any two alpha olefins having up to 20 carbon atoms wherein the content of each of the two comonomers exceeds about 10% by weight of the copolymer, and combinations thereof.

16. The non-woven fabric composite, such and such, is claimed in clause 1, characterized in that at least one of the first and second thermoplastic polymers comprises a wettable polymer.

17. The non-woven fabric composite, as claimed in clause 15, characterized in that the wettable polymer comprises a material selected from the group consisting of polyamides, polyvinyl acetates, acetates! of saponified polyvinyl, saponified vinyl ethylene acetates, other hydrophilic polymers, and combinations thereof.

18. The non-woven fabric composite, as claimed in clause 1, characterized in that at least one of the first and second polymers comprises an elastic polymer.

19. The non-woven fabric composite, as claimed in clause 18, characterized in that the elastic polymer comprises a material selected from the group consisting of styrene-butadiene copolymers; single site catalyzed polypropylene, polyethylene and alpha olefin homopolymers and copolymers having a density of less than about 0.89 grams / cc; other amorphous polyalphadefins having a density of less than about 0.89 grams / cc; ethylene vinyl acetate copolymers; ethylene and propylene copolymers; and combinations thereof.

20. The non-woven fabric composite, such and such, is claimed in clause 1, characterized in that the thermoplastic bicomponent filaments comprise crimped filaments.

21. The non-woven fabric composite, as claimed in clause 20, characterized in that the thermoplastic polymer comprises a relatively elastic polymer and the second thermoplastic polymer comprises a relatively inelastic polymer. •• ¡.i.- »»., .-. agaS

22. The non-woven fabric composite, as claimed in clause 20, characterized in that the thermoplastic polymer comprises a relatively heat-shrinkable polymer and the second thermoplastic polymer comprises a polymer 5 relatively non-shrinkable by heat.

23. The non-woven fabric composite, as claimed in clause 1, characterized in that the thermoplastic bicomponent filaments further comprise a treatment 10 surface, the surface treatment includes a polymer selected from the group consisting of polyethylene waxes, polypropylene waxes, amorphous polyethylenes, amorphous polypropylenes, ethylene-propylene and butene-propylene copolymers containing more than 10% of each comonomer , ethylene terpolymers 15 and propylene and butene, styrene and butadiene glutinizing agents and rubbers, ethylene vinyl acetate copolymers containing more than 5% by weight of vinyl acetate, ethylene alkyl acrylates, poly (4-methyl-1-pentene), polymers and alpha copolymers olefin in which at least one alpha olefin has 4-20 atoms of 20 carbon, resins and hydrocarbon glutinizers, hot melt adhesives, and combinations thereof.

24. The non-woven fabric composite, as claimed in clause 1, characterized in that the matrix of The filament comprises a mixture of filaments joined with spinning and blown with fusion.

25. The non-woven fabric composite, as claimed in clause 1, characterized in that the third component comprises absorbent fibers selected from the group consisting of rayon fibers, cotton fibers, cellulose fibers, pulp fibers, superabsorbent fibers , fibrillated feathers, and combinations thereof.

26. The non-woven fabric composite, such and such, is claimed in clause 1, characterized in that the third component comprises particles selected from the group consisting of charcoal, clays, starches, superabsorbent particles, odor absorbers, and combinations thereof.

27. The non-woven fabric composite, as claimed in clause 1, characterized in that the third component comprises pulp fibers and a superabsorbent.

28. The non-woven fabric composite, as claimed in clause 1, characterized in that it comprises about 3-95% by weight of the thermoplastic bicomponent filaments and about 5-97% by weight of the third component.

29. The non-woven fabric composite, as claimed in clause 1 characterized in that about 5- ----- Sij-É-, A * ¿fc - ~ 65% by weight of the thermoplastic bicomponent filaments and around 35-95% by weight of the third component.

30. The non-woven fabric composite, as claimed in clause 1, characterized in that it comprises about 5-50% by weight of the thermoplastic bicomponent filaments and about 50-95% by weight of the third component.

31. A nonwoven fabric composite comprising: a matrix of substantially continuous thermoplastic bicomponent filaments including at least one adhesive polymer, and a third absorbent component that is contained within the matrix, selected from the group consisting of absorbent fibers, absorbent particles and combinations thereof; wherein the adhesive polymer facilitates the containment of the third component.

32. The non-woven fabric composite, as claimed in clause 31, characterized in that the bicomponent filaments comprise the thermoplastic polymers first : .__ .. ».'---- and second arranged in different zones through a cross section of the individual bicomponent filaments; Y One of the first and second thermoplastic polymers comprises the adhesive polymer.

33. The non-woven fabric composite, such and such, is claimed in clause 31, characterized in that the bicomponent filaments comprise the first and second thermoplastic polymers arranged in different zones through a cross-section of the individual bicomponent filaments; and the adhesive polymer is applied to another surface of the bicomponent filaments, and is in addition to the first and second thermoplastic polymers.

34. The non-woven fabric composite, as claimed in clause 31, characterized in that the adhesive polymer comprises a polyolefin wax.

35. The non-woven fabric composite, as claimed in clause 31, characterized in that the adhesive polymer comprises a material selected from ethylene-propylene copolymers, copolymers of butene and propylene, and terpolymers of ethylene, propylene and butene.

36. The non-woven fabric composite, as claimed in clause 31, characterized in that the adhesive polymer comprises a styrene-butadiene polymer.

37. The non-woven fabric composite, as claimed in clause 31, characterized in that the adhesive polymer comprises an ethylene alkyl acrylate copolymer.

38. The non-woven fabric composite, such and such, is claimed in clause 31 characterized in that the adhesive comprises poly (4-methyl-1-pentene).

39. The non-woven fabric composite, as claimed in clause 31, characterized in that the adhesive polymer comprises ethylene vinyl acetate.

40. The non-woven fabric composite, as claimed in clause 31, characterized in that the adhesive polymer comprises an alpha-olefin copolymer which includes at least one monomer having 4-20 carbon atoms.

41. The non-woven fabric composite, as claimed in clause 31, characterized in that the adhesive polymer comprises a hydrocarbon. • «SgPL & je ^ jggt_é. I »» - '' ** & *1 . 4v "-SB - * * ^ - * ^ £, -.

42. The composite of non-woven fabric, such and cone is claimed in clause 31 characterized in that the adhesive polymer comprises a hot-melt polymer.

43. The non-woven fabric composite, as claimed in clause 31, characterized in that the third component comprises pulp fibers.

44. The non-woven fabric composite, as claimed in clause 31, characterized in that the third component comprises a superabsorbent material.

45. The nonwoven fabric composite, such and I run is claimed in clause 31 characterized in that the third The component comprises pulp fibers and a superabsorbent material.

46. An absorbent article comprising: A composite nonwoven fabric including a matrix of substantially continuous thermoplastic bicomponent filaments having adhesive properties / an absorbent material within the matrix; 25 bicomponent filaments include the first and second thermoplastic polymers arranged in zones ^^^^^^^^^^^^^^^^^^^^^ -__ ------- __-- ^^^ ll - ^ r - ^ - ¿- ^. ».-- aste .---. . , __ £ &"..". ». ' < '- distinct through a cross section of the individual bicomponent filaments; The absorbent material is selected from the group consisting of particles, fibers and combinations thereof.

47. The absorbent article, as claimed in clause 46, characterized in that the absorbent material comprises pulp fibers.

48. The absorbent article, as claimed in clause 46, characterized in that the absorbent material comprises a superabsorbent.

49. The absorbent article, as claimed in clause 46, characterized in that the absorbent material comprises a combination of pulp fibers and superabsorbent.

50. The absorbent article, as claimed in clause 46, characterized in that it comprises a cleaning cloth.

51. The absorbent article, as claimed in clause 46, characterized in that it comprises a diaper.

52. The absorbent article, as claimed in clause 46, characterized in that it comprises underpants. - '..-.- «asa-! B- ----: - .¿. f _ ^ _ L_: __-___, _. SUMMARY An improved nonwoven fabric composite is formed by combining the bicomponent thermoplastic filaments having adhesive properties with a selected component of other fibers and particles. The bicomponent filaments include different regions of the first and second incompatible polymers through a cross section of the individual filaments. After the 10 bicomponent filaments are combined with other fibers and / or particles, the adhesive properties of the bicomponent filaments result in a fabric or matrix of filaments having an improved ability to trap, catch in a trap and contain the other fibers and / or particles inside the tissue or 15 matrix. The non-woven fabric composite is particularly useful for making absorbent articles, which require stability and optimum levels of fibers and / or absorbent particles. -. _ - ._-- S ---_._-_ ... --_.-__- *. • w ---------- MM | fp (|| t1",.« «.:,..-___. -___ s - ¿__?