MXPA99011225A - Non-woven surfactant compositions for enhanced durability and wettability - Google Patents

Abstract

The present invention discloses a non-woven fabric treated with a combination of at least two selected surfactants provide a lasting and controlled wettability to the fabric. The lasting wettability provided by the treated fabric is useful in a huge variety of absorbent products which are typically exposed to multiple fluid discharges before waste.

Description

COMPOSITIONS OF NON-WOVEN SULFACTOR FOR DHA DURABILITY IMPROVED WETTING This application is a continuation in part of the United States of America patent application, Series 09 / 138,157 filed on August 21, 1998, which in turn is a continuation in part of the United States of America patent application. 08 / 994,828 filed on December 19, 1997, which in turn is a continuation in par of the United States patent application of Améric Series No. 08 / 898,188, filed July 22, 1997, when descriptions are incorporated here for reference. The first initial request claims priority of the provisional request of the United States of America, No. _60 / 025, 621 filed on December 4, 1996.

FIELD OF THE INVENTION This invention relates to non-woven fabrics treated with surfactant compositions which provide a combination of durability and controlled wetting. M specifically, the invention relates to non-woven fabrics treated with a durable surfactant and a fast, slow or intermediate rate wetting surfactant, whether by separate treatment or a single combined treatment. BACKGROUND OF THE INVENTION The non-woven fabrics and their manufacture have been subject to an extensive development resulting in a wide variety of materials for numerous applications. For example, lightweight nonwoven fabrics and cover structure are used in personal care items such as disposable diapers such as lining fabrics that provide a dry contact with the skin but easily transmit fluid to more absorbent materials, which may be some nonwovens of a different composition and / or structure Heavier weights nonwovens may be designed with pore structures which are made suitable for filtration, absorbent and barrier applications such as wrappers for articles that they will be sterilized, cleansers and protective garments for medical, veterinary or industrial uses. N Even heavier weight fabrics have been developed for more recreational, agricultural and construction uses. These are not without a few of the practically limitless examples of non-woven types and their uses that are known to those skilled in the art who will recognize that new nonwovens and uses are constantly being identified. They have also developed different way of equipment to make non-woven materials that have desired structures and composition suitable for these uses. Examples in such processes include spun bonding, meltblowing, carding and others, which will be described in greater detail below. The present invention generally has application to non-wovens as will be apparent to one skilled in the art and should not be limited by reference or by example to specific non-wovens which are merely illustrative It is not always possible to efficiently produce a non-woven having all the desired properties to the formed one, and often it is necessary to treat the nonwoven to improve the properties such as the wettability by means of one or more fluids, the electrostatic characteristics, conductivity and the softness to name only a few examples. Conventional treatments involve pasts such as embedding the tissues such as embedding the non-woven treatment bath, coating or spraying the nonwoven with treatment composition, printing the nonwoven with the treatment composition. For reasons of cost and others, it is usually desired to employ a minimum amount of the treatment composition which will produce the desired effect with an acceptable degree of uniformity.

When a nonwoven fabric is formed of a hydrophobic material, eg, of polyolefin, it is often desirable to modify the surface of the woven fabric using a hydrophilic surfactant to increase the wettability of the fabric. An external hydrophilic surfactant and typically applied to the surface of the non-woven fabric. Internal hydrophilic surfactant is typically mixed with polymer used to form the nonwoven fabric and then migrate the surface after the nonwoven has been formed.

The external and internal hydrophilic surfactants can be characterized in terms of suitability and wettability. The durability of the surfactant generally refers to its ability to withstand stresses, such as the repeated washing cycles of the non-woven fabric, without being removed from the fabric or otherwise losing its effectiveness. Wettability of a surfactant generally refers to the ability to transform a hydrophobic non-woven fabric into a cloth which readily assimilates and distributes to aqueous liquids. Surfactants which cause an otherwise hydrophobic woven fabric to absorb liquids at a relatively rapid rate with high fluid intake volumes, are referred to as fast wetting surfactants. Surfactants which cause the non-woven fabric to absorb aqueous liquids at a relatively slow rate, with a low fluid intake volume, are referred to as slower surfactants. In addition to the type of surfactant, other factors affect the ability of the non-woven fabric to absorb liquids including without limitation the type of non-woven fabric type of nonwoven polymer, the fiber size and the densified capacity of the surfactant like this one. applies Surfactants that have a high durability are desirable for a variety of reasons. However, the durable surfactants provide sufficient wetting and lend themselves to the optimization of the desired wetting characteristics for individual end use applications. There is a need and desire for a surfactant composition that has both durability and controlled wetting, whether the desired wetting is rapid or medium. There is also a need or desire for a non-woven fabric that has a durable wetness that has a rate and is predetermined and controlled.

SYNTHESIS OF THE INVENTION The present invention is directed to a surfactant combination, and to a non-woven fabric treated with a surfactant combination. The surfactant combination includes a first surfactant which provides durable wetting characteristics, and a second surfactant which controls the wetting rate (fast, slow or intermediate). Used combination, the combination of surfactant provides a non-woven tea that has humidifying characteristics that are amburable and of certain rate.

The surfactant combination provides a nonwoven tea with the ability to support at least two advantageously at least three discharges using the crib test described above. The first surfactant just did not need to provide this level of durability. Instead of this, what is important in the combination of surfactants (taking into account all the synergies between them) provide a woven fabric that has this level of durability.

The combination of surfactant also provided the non-woven fabric with a controlled rate of wetting as characterized by the cradle test described above. Again, it is not important that the second surfactant only provide - desired fluid rate. Instead of. this, what is important is how the two surfactants behave in the environment in which they coexist with one another. In this environment, the surfactants together (taking into account all synergies between them) should provide a desired wetting rate as well as a durable wetting to the non-woven fabric.

With the foregoing in mind, it is an advantageous feature of the invention to provide a combination during which it imparts a durable wettability to a non-woven fabric at a rapid, intermediate or slow rate of wetting with an aqueous medium.

It is also a feature and an advantage of the invention to provide a non-woven fabric which is treated with the surfactant combination to effect a durable wetting at a rapid, intermediate or slow wetting rate.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a schematic of a cradle test apparatus used in the test procedure described below.

DEFINITIONS The term "nonwoven fabric or fabric" means fabric having a structure of individual fibers or threads which are "laid", but not in a regular identifiable manner as in a woven fabric. Fabrics or woven fabrics have been formed from many processes such as, for example, meltblowing processes, bonding and spinning processes, air laying processes and carded and bonded tissue processes. The basis weight of the woven fabric is usually expressed in ounces of square yarn (osy) or 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) The term "microfibers" means small diameter fibers that have an average diameter no greater than 75 microns, for example, that they have an average diameter of about one to three microns, or more particularly, the microfibers can have an average diameter of about one to about 30 microns. Another frequently used expression of fiber diameter is denier, which is defined as grams per 9000 metr of a fiber. For a fiber that has a circular cross section, if the denier can be calculated as a fiber diameter in square microns, multiplied by the density grams / cubic centimeter, multiplied by 0.00707. A low denier indicates a finer fiber and a higher denier indicates a heavier fiber or thickness. For example, the diameter of polypropylene fiber used given as 15 microns can be denier by square, multiply the result by .9 g / cc and multiply by .00707. Therefore, a polypropylene fiber of 15 microns has a denier of around 1.4 (152 x 0.89 x .00707 = 1.415). Outside the United States, the measurement unit is more commonly the "tex", which is defined as grams per kilometer of fiber. The tex can be calculated as denier / 9.

The term "spunbonded fibers" refers to fibers of diameter formed by extruding the melted thermoplastic material as filaments from a plurality of fine capillary vessels of a spinner having a circular configuration or other configuration with the diameter of the extruded filaments. being rapidly reduced, such as for example, it is indicated in U.S. Patent No. 4,340,563 issued to Appel et al., and in United States of America No. 3,692,318 issued to Dorschner et al. United States of America No. 3,802,817 issued to Matsuki et al., in US Pat. Nos. 3,338,992 and 3,341,394 granted Kinney, in United States Patent No. 3,502,763 issued to Hartman, in the patent of the United States of America No. 3,502,538 granted to Peterson, and in the patent the United States of America No. 3,542,615 granted to Dobo others, each of which is incorporated here in its total by reference. The yarn-bound fibers are generally not sticky when they are deposited on the collecting surface. Yarn-bonded fibers generally continuous and frequently contain average diameters greater than about 7 microns, more particularly between about 10 and 30 microns.

The term "melt blown fibers" means fibers formed by extruding a melted thermoplastic material through a plurality of matrix capillaries, usually circular and thin like melted filaments or filaments in gas streams, (eg, air), heated to high speed and convergent which attenuate the filament of molten thermoplastic material to reduce its diameter which can be to a microfiber diameter., the meltblown fibr are carried by the stream of gas at speed and are deposited on a collecting surface to form a fabric of blown fibers with dispersed orange blossom. Such a process is described, for example in the United States of America patent No. 3,849,241 granted to Butin. The meltblown fibers are microfibers which can be continuous or discontinuous, are generally smaller in diameter, and are generally self-bonding when deposited on a collecting surface. The meltblown fibers used in the present invention are preferably essentially continuous in length.

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

The term "basic fibers" means fibers which are natural or cut from a filament manufactured prior to being formed into a fabric, and which have an average length varying from about 0.1-15 centimeters, m commonly of about 0.2-7. centimeters.

The term "bicomponent fibers or filaments" refers to fibers which have been formed from at least extruded polymers of separate extruders but spun to form a fiber.The polymers are arranged in a zon arranged in essentially different way through the section. of the bicomponent fibers and which extend continuously along the length of the bicomponent fibers The configuration of such bicomponent fiber can be, for example, a sheath / core arrangement wherein one polymer is surrounded by another or it may be a side-by-side arrangement of "islands in the sea." The bicomponent fibers are taught in U.S. Patent No. 5,108,820 issued to Kaneko et al., in the United States of America patent. No. 5,336,552 issued to Strack et al. And in United States of America Patent No. 5,382,400 issued to Pike et al., Each of which is hereby incorporated in its entirety by reference.

For 2 component fibers, the polymers may be present in proportions of 75/25, 50/50, 25/75 any other desired proportions. Conventional additives, such as pigments or surfactants can be incorporated into one or both polymer streams, applied to the filament surfaces.

The term "component fiber" refers to a fiber formed from one or more extruders using only one polymer. This does not mean that fibers formed from polymer to which small amounts of additives have been added for color, antistatic properties, lubrication, hydrophilicity, are excluded. etc. These additives, for example titanium dioxide for color, are generally present in amounts of 5% per po and more typically of about 2% by weight.

The term "polymer includes but is not limited to homopolymers, copolymers, such as, for example, block, graft, orange and alternating copolymers to terpolymers, etc. and to mixtures and modifications thereof. Unless specifically limited in this way, the term "polymer" will include all geometric configurations of the material These configurations include, but are limited to, isotactic, syndiotactic, and atactic symmetries. The term "pulp fibers" refers to fibr from natural sources, such as from woody and non-woody plants Woody plants include, for example, deciduous and coniferous trees Non-woody plants include, for example, cotton, flax, grass, esparto, bencetdcigo, straw, jute, and bagasse The term "average fiber length" refers to the average length of the fibers determined using the Kajaani fiber analyzer, model No. FS-100 available from Kajaani Oy Electronics in Kajaani, Finland. Under the test procedure, a fiber sample is treated with a macerator liquid to ensure that no pieces of fiber are present. Each fiber sample is dispersed in hot water and diluted to a concentration of about 0.001%. Individual test samples were carried out in part from 50 to 500 milliliters of the diluted solution and tested using the fiber analysis procedure Normal kajaani The average fiber lengths can be expressed by the following equation: S (i * ^ / n X¡> 0 where = maximum fiber length, X, = individual fiber length, n, = number of fibers having the length X, n = total number of measured fibers.

The term "superabsorbent material" refers to an organic or inorganic material soluble in water per swellable in water, under the most favorable conditions, absorbing at least about 15 times its weight, and more desirably at least about 30 times its weight. times its weight in an aqueous solution containing 0.9% by weight of sodium chloride The term "air binding" or " " means a process of joining a nonwoven, for example a bicomponent fiber fabric wherein the air is hot enough to melt one of the polymers from which the fibers are made of the fabric and that are forced through the fabric.The melting and the resolidification of polymer provides the union.

The term "thermal point union" involves passing the fabric or fabrics of fibers to be joined between a heated calendered roller and an anvil roller. The calendering rod usually has, if not always, somehow patched in such a way that the entire fabric is not attached across its entire surface. As a result of this, several patterns have been developed for calendering rollers for functional as well as aesthetic reasons. An example of a pattern has points and is the Hansen Pennings pattern or "H &P" co around 30% area joined with about 200 joints / square inch, as taught in the United States of America patent No. 3,855,046 awarded to Hansen Pennings. The H &P pattern has bolt-joint or square-point areas where each bolt has a side dimension of 0.03 inches (0.965 mm), a spacing of 0.070 inches (1778 mm) between the bolts, and a joint depth of 0.023 inches (0.564 mm). The resulting pattern has a bound area of about 29.5%. Another typical point bonding pattern is the Hansen Pennings or "H &P" bonding pattern, which produces a 15% square pin joint area that has a side dimension of 0.037 inches (0.94 mm), a bolt spacing of 0.097 inches (2.464 mm) and a length of 0.039 inches (0.991 mm). Another typical point union pattern designated "714" has a square point joining area 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 (0.838 mm). The resulting pattern has a bound area of about 15%. Still another pattern is the star pattern C which has a bound area of about 16.9%. The star pattern C has a bar design in the transverse direction or "corduroy" interrupted by shooting stars. Other common patterns include a diamond pattern with slightly repetitive off-center diamonds and a wire-weave pattern that looks like the name suggests, for example, a window grid. Typically, the percent of bonded area ranges from about 10% to about 30% of the area of the fabric laminated fabric. As is well known in the art, point bonding holds the laminate layers together, as well as the one imparting integrity for each individual layer, by joining the filaments and / or fibers within each layer.

The term "personal care product" means diapers, training underpants, swimwear, absorbent undergarments, baby bibs, adult incontinence products, and women's hygiene products.

The term "durable wettability" or "Durably wettable" means the ability to withstand at least two and advantageously at least three discharges using the run-off test described below.

The term "hydrophilic" or "wettable" means that the finished polymeric material has a surface free energy such that the polymeric material is an adhesive through an aqueous medium. For example, a liquid medium of which water is the main component. The finished polymeric material may have been treated by a surfactant, a combination of surfactants, or other finishing agents.

Test Procedure The "cradle test" mentioned here, (also known as the Little MIST test) was carried out as follows. Referring to Figure 1, two layers 12 and 14 of a sample of non-woven fabric were weighted, and placed on the valley of an ac cuic 10, against the inner wall of the cradle. The cu has a length (on the page) of 33 cm with the front and rear ends blocked, a height of 19 centimeters, or distance between the upper arms 18 and 20 of 30.5 centimeter and an angle between the upper arms of 60 °. The crib has a 6.5 cm wide slot at its lowest point running the length of the crib to this page.

Each layer of non-woven fabric can be rectangular, with dimensions of 2.5 by 7.0 inches or 3.0 p by 7.0 inches. Then, 80 milliliters of blood bank salt water (1% aqueous NaCl) were injected into the center specimen at a rate of 20 ml / second using a standard nozzle at the center of the material and 0.25 inches above the material. Fluid not contained by the non-woven fabric (referred to as "runoff") flows over the edges of the sample and through the center of the slot 16 to the cradle. The sample material is then removed immediately from the crib and weighed.

The fluid contained by the non-woven fabric d sample is used to calculate the operating parameter, P which reflects the amount of the liquid retained based on the sample volume of the fabric. grams of fluid content x 100% cc of sample dry grams of fluid contained per dry sample density (a / cc) x 100 grams of dry sample The sample of non-woven fabric is then desorbed by placing on the top of a composite superabsorbent material / eraser for 5 minutes. The compound contains 40% by weight of U.S. Alliance Coos Pines CR-2054 60% by weight superabsorbent from Stockhause Company FAVOR 870. Other comparable materials may be used. Then, the desorbed sample is put back into the cradle where it receives a second insult discharge of the fluid. This procedure was repeated for a total of 3 fluid insults for about 30 minutes between the insults. The non-woven fabric sample was considered to have curable hydrophilic properties without its operating parameter does not fail for more than 10% over 3 discharges.

The fluid insult rate is also relevant for this test. Generally, the faster the discharge, the greater the demand on the thickness of the specimen for assimilating or spreading the liquid. For the test of this invention, it maintained a fixed rate of 20 ml / second.

DETAILED DESCRIPTION OF THE INCORPORATIONS CURRENTLY PREFERRED The starting material for the invention is a non-woven fabric that includes a plurality of filaments made of 1 or more polymers treated with a combination of hydrophilic surfactan. The non-woven fabric can be a spunbond, meltblown, bonded and carded fabric, or other non-woven fabric or be present in a single layer or in a multilayer composite including one or more layers of fabric. non-woven The combination of hydrophilic surfactant can be a combination of internal or external surfactant. A combination of internal surfactant is one which is mixed with the polymer used to be the non-woven fabric and which migrates the surface of the non-woven fabric filaments during and / or after the formation of the filaments. Frequently, emigration results from a stimulus, such as the heat applied to the filaments. An external surfactant is one, which is applied externally to the surface of the filaments of the non-woven fabric after they are formed. An external surfactant can be applied by embedding, after which they are formed. The external surfactant may be applied by soaking, soaking, spraying, or otherwise coating the non-woven fabric with a surfactant-containing medium. External internal surfactant inclusion techniques are generally well known in the art.

The combination of surfactant used according to the invention is a combination of two or more surfactants which impart a durable hydrophilicity to a non-woven fabric as a controlled wettability rate. Generally, non-woven tea is constructed of a thermoplastic polymer which is either hydrophobic or insufficiently hydrophilic. The non-woven fabric class mentioned herein is "insufficiently hydrophilic hydrophobic" refers to non-woven fabrics which exhibit a performance parameter of less than using the crib test described above, when the woven fabric is not treated with a hydrophilic surfactant.

A wide variety of thermoplastic polymers can be used to build the nonwoven fabric, including limitation polyamides, polyesters, polyolefins, ethylene and propylene copolymers, ethylene copolymers of propylene with a C4-C20 alpha-olefin, ethylene terpolymers with propylene and C4-C20 alpha-olefin, the ethylene vinyl acetate copolymers, the propylene vin acetate copolymers, the styrene-poly (ethylene-alpha olefin) elastomers, the polyurethanes, the AB block copolymers where A is formed of poly (vinyl arene) halves such as polystyrene and B is an elastomeric middle block such as a conjugated diene or a lower alkene, polyethers, polyether stere polyacrylates, alkyl ethylene acrylates, polyisobutylene polybutadiene, isobutadiene-isoprene copolymers, combinations of any of the above. Polyolefins are preferred. Polyethylene and polypropylene homopolymers and copolymers are most preferred. The fabrics may also be constructed of bi-constituent bicomponent filaments or fibers, as defined above. Non-woven fabrics can have a wide variety of basis weights, preferably varying from about 10 grams per square meter (gsm) to about 120 gsm. " .. . . _.

It should be understood that the invention is limited to the use of hydrophobic and insufficiently hydrophilic polymers. The combination of controlled and durable wetting rate surfactant can also be used to increase the wetting performance of nonwoven fabric polymers which are already hydrophilic, as indicated by an operating parameter of at least 30% without hydrophilic surfactant .

The hydrophilic combination of surfactants d provide a durable wetting at a controlled wetting rate. The combination may include two or surfactants, one of which independently provides durable wetting, and the other of which independently provides controlled tamping. Alternatively, the combination of surfactant may include two or more surfactants which, taken alone, provide one or both properties, but which provide a controlled and durable rate wetting when acting together in synergy.

A combination of hydrophilic surfactant provides "durable wetting" if the performance parameter resulting from the third liquid insult is greater than or equal to 10% less than the operating parameter resulting from the first liquid discharge using the crib test, described above.

The combination of hydrophilic surfactant to provide moisture at a controlled rate can be rapid, intermediate or slow. A surfactant combination provides a rapid wetting rate if a non-woven fabric treated with the surfactant combination (e.g., a non-woven fabric made of a hydrophobic or insufficiently hydrophilic thermoplastic polymer) exhibits an operating parameter of at least 50% for The first fluid insult using the cradle test described above, a combination of hydrophilic surfactant provides an intermediate wetting rate if the operating parameter for the first fluid insult is at least 40% and less than 50%. A combination of hydrophilic surfactant provides a slow wetting rate if the operating parameter for the first fluid insult is at least 30% and less than 40%. Operating parameters below 30% are considered insufficient.

The combination of hydrophilic surfactant includes at least the first and second surfactants. The first surfactant should be a durable surfactant. The prime surfactant should include a compound selected from the hydrogenated and ethoxylated fatty acid ester, a monosaccharide, or monosaccharide derivative, a polysaccharide or a polysaccharide derivative, and combinations thereof. For example, the first surfactant may include a mixture of sorbitan monooleate and ethoxylated hydrogenated castor oil. One of the AHCOVELB Base No. 62 surfactant available from Hodgson Chemical Company.

Another first surfactant is a castor oil derivative of ethylene oxide. One such surfactant is sold by ICI Surfactant, Inc., under the name ATMER®8174.

Another suitable first surfactant may include selected polyolefin glycol, or a derivative of a polyolefin glycol. Examples of the derivatives include the monooleates and the polyolefin glycol dioleates monolaurates and polyolefin glycol dilaurates, and the alkyl esters of polyolefin glycols. The MAPEG surfactants available from PPG Industries are made from the previous derivatives of polyethylene glycol.

Another suitable first surfactant is surfactan LUROL®, available from Goulston Technologies, Inc. LUROL® surfactants are believed to include a polymer, a hydrophilic couple with multiple hydrophobic portions. The hydrophobic particles help the surfactant interface and adhere to a hydrophobic polymer substrate. The LUROL® 6473 and 7514 s two samples of two durable surfactants.

The second surfactant can be a controlled rate wetting surfactant. The second surfactant can be a second rapid wetting surfactant, intermediate wetting surfactant or a slow wetting surfactant.

Examples of the second surfactants included organosilicon compounds. The MASIL® SF-19 available BASF Chemical Company, is an ethoxylated trisiloxa base surfactant which typically behaves as a rapid wetting surfactant. Certain polyolefin glycol derivatives serve as intermediate slow surfactants. ANTORO available from Rhone Poluene Chemical Company, includes ethoxylate alkyl ester derived from polyethylene glycol and polypropylene glycol and may cause slow or intermediate wetting depending on the substrate. Another second surfactant may include an alkyl polyglycoside. GLUCOPON® 220UP is a 60% solution of octyl polyglycoside and 40% water and can serve as a slow or intermediate surfactant when used in combination with the first surfactant such as a mixture of ethoxylated hydrogenated ricin oil and monooleate sorbitan Other second surfactants include the ionic sulfonate-based surfactants, for example, sulfonate dodecylbenzene sold under the trademark BIOSOFT® d Stephen Company. Another ionic surfactant is AEROSOL OT sold by Cytec Corporation. Ionic surfactants are frequently only of fast but not durable wetting.

The surfactant combination may include about 5-95 parts by weight of the first surfactant and about 5 95 parts by weight of the second surfactant, based on dry solids, per 100 parts by weight of both surfactants combined. Typically, the surfactant combination may include about 95-90 parts by weight of the first surfactant and about 10-75 parts by weight of the second surfactant. Desirably, the surfactant combination may include about 40-8 parts by weight of the first surfactant and about 10-6 parts by weight of the second surfactant. Regardless of how the surfactants alone behave, the first surfactant generally contributes to the durability for the combination, the second surfactant generally contributes to the controlled rate humedeciment. Frequently, the operation of both is synergized and increased by the combination.

The surfactant combination can be applied using internal and / or external application techniques well known in the art. The first and second surfactants can be applied in separate parts, or together. If one or both surfactants are applied externally using a solvent, the solvent can be removed using conventional evaporation techniques. On a weight basis of solvent-free, the surfactant combination should constitute about 0.1-10% by weight of the non-woven fabric to which it is preferably applied about 0.5% by weight, more preferably 1-3% by weight. weight. Higher levels of the surfactant combination are less desirable, due to cost and other issues. The levels, which are very low, tend to impart less wettability to the non-woven fabric.

The non-woven fabrics formed have wettability which both durable and of certain rate. Treated non-woven fabric can be used in a wide variety of absorbent product applications including, in particular, absorbent products for personal care. Absorbent personal care products include diapers, training pants, swimwear, absorbent interiors, baby wipes, adult incontinence products, women's hygiene products, and the like. , as well as other products taking and arising material. In most absorbent products, the treated nonwoven fabric is used as a cover sheet or as a containment matrix for an absorbent media. An absorbent medium may include, for example, pulp fibers alone or in combination with a superabsorbent material. The treated non-woven fabric can also be used in medical absorbent products, including limiting inner pads, absorbent covers, bandages and medical cleansing wipes.

The pulp fibers may be any of the high average fiber length pulp, the low average fiber length pulp, or mixtures thereof. Preferred pulp fibers include cellulose fibers. The term "high average fiber length pulp" refers to pulp containing a relatively small amount of short fibers and non-fiber particles. The upper fiber length pulps typically have an average fiber length greater than about 1.5 mm, preferably around 1.5-6 mm as determined by a fiber optic analyzer, such as a Kajaani tester as mentioned above. The sources generally include non-secondary (virgin) fibers as well as secondary fiber pulp which has been screened. Examples of high average fiber length pulps include virgin softwood pulp bleached and bleached n.

The term "low average fiber length pulp" refers to pulps that contain a significant amount of short fibers and give non-fiber particles. The low average fiber length pulps have an average fibr length that is less than about 1.5 mm, preferably about 0.7-1.2 mm, as determined by an optical fiber scanner such as a Kajaani tester to which Reference has been made above. Examples of low fiber length pulps include virgin hardwood pulp as well as secondary fiber pulp from sources such as office waste, newspaper or cardboard clipping.

Examples of high average fiber length wood pulps include those available from U.S.

Alliance Coosa Fines Corporation, under the trade designations Longlac 19, Coosa River 56, and Coosa River 57. Pulp lengths of low average fiber may include some pulp of virgin hardwood and secondary fiber pulp (for example recycled) from sources They include newspaper, cardboard reclaimed and office waste. The mixtures of high average fibr length and low average fiber length pulps may contain a predominance of low average fibr length pulps. For example, blends may contain more than about 50% pulp of average fiber length under less than 50% by weight of average high fiber length pulp.

The term "superabsorbent" or "superabsorbent material" refers to an organic or inorganic material insoluble in water swellable in water capable, under the most favorable conditions, of absorbing at least 15 times its weight more desirably, at least about 30 times its weight in an aqueous solution containing 0.9% by weight of sodium chloride.

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

Examples of the synthetic superabsorbent material polymers include the alkali metal salts of poly (acrylic acid) and poly (methacrylic acid), poly (acrylamide), poly (vinyl ethers), maleic anhydride copolymers with ethers of vinyl 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 the total or partially synthetic superabsorbent polymers may also be useful in the present invention. Other suitable absorbent gelation materials are described by Anderson et al. In U.S. Patent No. 3,901,236 issued August 26, 1975.

The processes for preparing the absorbent and synthetic gelation polymers are described in U.S. Patent No. 4,076,633 issued February 28, 1978 Edwards et al. And U.S. Patent No. 4,286,082 issued on October 25, 1978. August 1981 to Tsubakimoto and others The superabsorbent materials can be xerogels which form hydrogels when wetted. The term "hydrogel" however has been commonly used to also refer to both wetted and unmoistened forms of superabsorbent polymer material. The superabsorbent materials may be in many forms such as chips, powders, particles, fibers, continuous fibers, filament networks, solution yarns and fabrics. The particles may be of any desired shape, for example, spiral or semi-spiral, cubic, rod-type, polyhydric, etc. Needles, flakes, fibers and combinations can also be used.

The superabsorbents are generally available in particle sizes ranging from about 20 to about 100 microns. Examples of commercially available particulate superabsorbents include the SANWET® IM 3900 and the SANWET® IM-5000P, available from Hoescht Celanese, located in Portsmouth, Virginia, DRYTECH 2035LD available from Dow Chemical Company, located in Midland, Michigan, and FAVOR ® 880, available from Stockhausen, located in Greensboro, North Carolina. An example of a fibrous superabsorbent is OASIS® 101, available from Technical Absorbents located in Grimsby, United Kingdom.

As indicated above, the non-woven fabric can be a cover sheet or a matrix for an absorbent medium. When used by a matrix, the non-woven filaments can be combined with pulp fibers and (optionally) with a superabsorbent material using processes well known in art. For example, a coform process may be employed, in which at least one melt blown die head is arranged near the product by means of which other materiale is added while the fabric is being formed. The coform processes are described in U.S. Patent No. 4,818,464 to Lau and 4,100,324 to Anderson et al., The descriptions of which are incorporated herein by reference. Essentially continuous bicomponent filaments and pulp fibers can also be combined using hydraulic entanglement or mechanical entanglement. A hydraulic entanglement process is described in United States of America Patent No. 3,485,706 issued to Evans, whose description is incorporated herein by reference.

When the thermoplastic non-woven filaments are used as a matrix for a non-woven absorbent fabric composite, the composite should contain about 5-97% w weight of pulp fibers, preferably about 35-95 wt% pulp fiber weight, more preferably around 50-95 by weight pulp fibers. When the superabsorbent material is present, it should constitute about 5-90% by weight of the compound, preferably about 10-60% by weight, more preferably about 20-50% by weight. In either case, the thermoplastic nonwoven matrix may constitute about 3-95% by weight of the compound preferably about 5-65% by weight, more preferably about 5-50% by weight.

After the combination of the ingredients together, the absorbent nonwoven composite can be joined together using the thermal spot bond or the air bonding techniques described above to provide a coherent and high integrity structure.

Examples Examples 1-18, the non-woven fabric used was a polypropylene / polyethylene side-by-side bicomponent. The surfactants were added internally by combining in one or both polymer resins using a 30 mm twin screw extruder prior to forming. of the filaments joined with yarn. The resultant surfactant / polymer concentrates were then added to one or both streams melted in the fiber spinning process prior to extrusion. The resulting treated nonwoven fabrics were then evaluated using the crib test described above. For each of these tests, two samples of rectangular tel were used that have dimensions of 2.5 by 2.70 inches. The results of the evaluations are shown in table 1. ~ t Table 1: Surfactantßs Added Internally 15 twenty * (Tests with 3x7 samples in a co-operation with the feren fifteen For examples 19-33, the same non-woven fabric was used, but the surfactants were added externally instead of internally. An emulsion / aqueous surfactant mixture was applied to the non-woven fabric using embedding followed by vacuum or foam application. At the levels of surfactant employed (on a solvent-free base) they were somewhat slower than those for Examples 1-18. However, the surfactants are added externally instead of internally, the aggregate complete amount is present on the surface where the greater wetting is achieved. The treated non-woven fabrics were evaluated using the crib test. The results are shown in Table 2.

Table 2: Surfactantßs Aggregates Externally 15 twenty As shown above, both surfactant added internally and externally, only certain surfactants combined gave both durability and controlled humidification. Individually used surfactants which exhibited sufficient moisture did not have a durability when applied to non-woven fabrics. Notably, only some of the surfactant combinations delivered both durability and controlled wetting while others did not. Also, the performance of a particular surfactant combination varied with the total amount applied and the proportion of ingredients used.

Examples 34-57 illustrate the operation of additional surfactants, alone and in combination with each other. Again, a polypropylene / polyethylene side-by-side bicomponent non-woven fabric (with average fiber size of 1.1 denier per fiber, 2.7 gram per square yard weight and a density of 0.03 g / cc) was used. The surfactants were added externally. For some of the samples (examples 33-36 and 43-45) a smaller amount of hexane was added (0.5% with surfactants for ease of treatment) Table 3 gave the results of the cradle test Again, u surfactant (LUROL) which is only slow insufficient, operated much faster (with durability) when used with a co surfactant and also operates more effectively at the lower level of the combination.

Table 3: Externally Added Surfactants Even when the embodiments described herein are currently preferred, various modifications may be made if departing from the spirit and scope of the invention. The scope of the invention is indicated by the appended claims and all changes that fall within the meaning and equivalent range are intended to be encompassed here.

Claims (41)

R E I V I ND I CA C I ON E S

1. A treated nonwoven fabric comprising polymer filaments treated with a surfactant combination including at least the first and second surfactant, treated nonwoven fabric having durable hydrophilic properties defined as an operating parameter initially of at least 30% the which does not fall by more than 1 between the first and third fluid discharges using the cradle test.

2. The non-woven fabric treated as claimed in clause 1, characterized in that the surfactant combination comprises a wet, fast and durable combination which receives an initial operating parameter of at least 50%.

3. The non-woven fabric treated as claimed in clause 1, characterized in that the surfactant combination comprises an intermediate and durable wetting surfactant combination, which exhibits an initial performance parameter of at least 40% and less than 50%

4. The non-woven fabric treated as claimed in clause 1, characterized in that the surfactant combination comprises a slow and durable wetting surfactant combination, which exhibits an initial performance parameter of at least 30% and less than 40% .

5. The non-woven fabric treated as claimed in clause 1, characterized in that at least one of the surfactants is applied internally.

6. The non-woven fabric treated as claimed in clause 1, characterized in that at least some of the surfactants are applied externally.

7. The non-woven fabric treated as claimed in clause 1, characterized in that the polymer filaments comprise bicomponent filaments which includes at least two distinct polymer components, wherein at least one of the polymer components is treated with The surfactant combination.

8. The treated nonwoven fabric as claimed in clause 1, characterized in that the prime surfactant comprises a polyolefin glycol derivative selected from polyolefin glycol monooleates and dioleates, polyolefin monolaurates and dilaurates, polyolefin alkyl glycol esters and combinations thereof.

9. The treated nonwoven fabric as claimed in clause 1, characterized in that the second surfactant comprises a siliceous organ compound.

10. The non-woven fabric treated as claimed in clause 8, characterized in that the second surfactant comprises an ethoxylated trisiloxane.

11. The non-woven fabric treated as claimed in clause 1, characterized in that the second surfactant comprises an alkyl ether derivative of polyolefin glycol.

12. The treated non-woven fabric as claimed in clause 8, characterized in that the second surfactant comprises an alkyl ether derivative of polyolefin glycol.

13. The treated non-woven fabric as claimed in clause 1, characterized in that the prime surfactant comprises a derivative of castor oil of oxidic ethylene.

14. The treated nonwoven fabric as claimed in clause 9, characterized in that the first surfactant comprises an ethylene oxide castor oil derivative.

15. The treated non-woven fabric as claimed in clause 1, characterized in that the first surfactant comprises a mixture of ethoxylated hydrogenated castor oil and sorbitan monooleate.

16. The treated non-woven fabric as claimed in clause 9, characterized in that the first surfactant comprises a mixture of ethoxylated hydrogenated castor oil and sorbitan monooleate.

17. The treated non-woven fabric as claimed in clause 1, characterized in that the second surfactant comprises an alkyl polyglycoside.

18. The treated nonwoven fabric as claimed in clause 15, characterized in that the second surfactant comprises an alkyl polyglycoside.

19. The non-woven fabric treated as claimed in clause 1, characterized in that the first surfactant comprises hydrophilic parts and a plurality of hydrophobic parts.

20. The treated nonwoven fabric as claimed in clause 19, characterized in that the second surfactant comprises an alkyl polyglycoside.

21. The non-woven fabric treated as claimed in clause 1, characterized in that the second surfactant comprises an ionic surfactant.

22. The non-woven fabric treated as claimed in clause 19, characterized in that the second surfactant comprises an ionic surfactant.

23. The treated non-woven fabric as claimed in clause 21, characterized in that the second surfactant comprises dodecylbenzene sulfonate.

24. The non-woven fabric treated as claimed in clause 19, characterized in that the second surfactant comprises a siliceous organ compound.

25. An absorbent nonwoven composite comprising an absorbent medium in combination with a woven fabric treated with a combination of surfactant, the treated woven fabric exhibits a durable and rapid wetting.

26. The absorbent nonwoven composite as claimed in clause 25, characterized in that the treated woven fabric serves as a cover sheet for the absorbent media.

27. The absorbent non-woven composite as claimed in clause 25, characterized in that the treated woven fabric n provides a matrix and the absorbent medium is contained within the matrix.

28. An absorbent non-woven composite comprising an absorbent medium in combination with a woven fabric treated with a surfactant combination, the treated non-woven fabric exhibits durable and intermediate wetting.

29. The absorbent nonwoven composite as claimed in clause 28, characterized in that the treated woven fabric serves as a cover sheet for the absorbent media.

30. The absorbent nonwoven composite such and co is claimed in clause 25, characterized in that the treated woven fabric provides a matrix and the absorbent medium is contained within the matrix.

31. An absorbent non-woven composite q comprises an absorbent medium in combination with a woven fabric treated with a surfactant combination, the treated non-woven fabric exhibits durable and slow wetting.

32. The absorbent nonwoven composite such and co is claimed in clause 31, characterized in that the treated woven fabric n serves as a cover sheet for the absorbent media.

33. The absorbent nonwoven composite as claimed in clause 31, characterized in that the treated woven fabric n provides a matrix and the absorbent medium is contained within the matrix.

34. A treated nonwoven fabric comprising polymer filaments treated with a surfactant combination including at least the first and second surfactants; the first surfactant comprises a polyolefin glycol or a derivative thereof; the second surfactant comprises a compound siliceous organ.

35. The treated non-woven fabric as claimed in clause 34, characterized in that the prime surfactant comprises a polyolefin glycol derivative comprising a material selected from polyolefin d-glycol monooleates and dioleates, glycol d-polyolefin monolaurates and dilaurates, esters of polyolefin alkyl and d combinations thereof.

36. The non-woven fabric treated as claimed in clause 34, characterized in that the second surfactant comprises a trisiloxane ethoxylate.

37. A treated nonwoven fabric comprising polymer filaments treated with a surfactant combination including at least the first and second surfactants; the first surfactant comprises a derivative d of castor oil of ethylene oxide; and the second surfactant comprises a compound d siliceous organ.

38. The non-woven fabric treated as claimed in clause 36, characterized in that the second surfactant comprises an ethoxylated trisiloxane.

39. A treated nonwoven fabric comprising polymer filaments treated with a surfactant combination including at least the first and second surfactants; the first surfactant comprises a polymer having both hydrophobic and hydrophilic parts; the second surfactant comprises a material selected from ionic surfactants and from siliceous organ compounds.

40. The treated nonwoven fabric as claimed in clause 39, characterized in that the second surfactant comprises an ethoxylated trisiloxane.

41. The treated non-woven fabric as claimed in clause 39, characterized in that the second surfactant comprises an ionic surfactant. SUMMARY A non-woven fabric treated with a combination of at least two selected surfactants provides the tel with controlled and durable rate wetting. E Durable wetting can be fast, intermediate or slow. The controlled rate humidification provided by the treated tel is useful in a wide variety of absorbent products which are typically exposed to multiple fluid discharges before disposal.