|Publication number||US3695269 A|
|Publication date||Oct 3, 1972|
|Filing date||Feb 12, 1970|
|Priority date||Feb 12, 1970|
|Publication number||US 3695269 A, US 3695269A, US-A-3695269, US3695269 A, US3695269A|
|Inventors||Malaney Frank E|
|Original Assignee||Johnson & Johnson|
|Export Citation||BiBTeX, EndNote, RefMan|
|Patent Citations (8), Referenced by (35), Classifications (9)|
|External Links: USPTO, USPTO Assignment, Espacenet|
United States Patent Malaney 1451 Oct. 3, 1972  METHOD OF MAKING ABSORBENT 2,845,070 7/1958 Lening ..l28/285 PRODUCTS WITH HIGHLY 2,862,251 12/1958 Kalwaites ..128/290 W ABSORBENT CORES AND 2,944,931 7/1960 Yang ..128/284 RELATIVELY DRY FACINGS 3,180,335 4/1965 Duncan et al. 128/287 72 F k E M I S 3,527,221 9/1970 Croon etal ..l28/287 1 a 3,101,520 8/1963 George et a1 ..12s/290 w NJ. 08876 [731 Assignee: Johnson and Johnson Primary ExamnerJhafles Rmnbaum L  Filed: Feb. 12 1970 Attorney-Alexander T. Kardos and Robert M1n1er  Appl. No.: 10,840  ABSTRACT Absorbent products comprising at least two fibrous  US. Cl ..1 28/284 layers: one layer comprising a highly absorbent fibrous  Int. Cl. ..A6lf 13/16 mass having excellent absorption and retention  Field of Search .....128/284, 287, 290 R, 290 W, capacity for body fluids and exudates; and a second 128/296; 26/ 18.6; 161/151, 156, 160; layer comprising a relatively dry, non-adherent, nonll7/l5, 66, 1 15, 138.8, 167 woven fabric facing made of relatively non-absorbent, hydrophobic, synthetic fibers bonded with a  References Cited hydrophobic binder material and processed so as to be UNIT E D STATES PATENTS provlded with increased loft and bulk proper 1es 3,059,313 10/1962 Harmon ..12s/290 w 1 2 Drawmg gums 3,327,708 6/1967 Sokolowski ..l28/290 W Z 20 A41 28 J2 a4 43 l I I W: o rmain fear/ j gemelf minimum m2 3.695269 INVENTOR METHOD OF MAKING ABSORBENT PRODUCTS WITH HIGHLY ABSORBENT CORES AND RELATIVELY DRY FACINGS The present invention relates to improved absorbent products for absorbing and retaining body fluids and exudates. More specifically, the present invention relates to improved absorbent products which have excellent absorption and retention capacity for body fluids and exudates but which are capable of presenting a relatively dry, non-absorbent, non-adherent, hydrophobic surface to the body emitting the fluids and exudates.
There are many absorbent products, such as diapers, sanitary napkins, surgical dressings, underpads, compresses, and the like, which are used for the absorption and retention of bodyfluids and exudates. Diapers, and particularly disposable diapers, are representative of this very large class of absorbent products and they will be used to illustrate more specific details of the present inventive concept. Such, however, is not intended to limit the broader aspects of the present inventive concept.
Disposable diapers normally comprise two or more layers of fibrous textile materials. One of these layers is normally an absorbent fibrous mass or core whose primary function is to absorb and retain the bulk of the body fluids and exudates. This absorbent fibrous mass or core is normally covered with a second layer or cover usually referred to as a facing sheet which is in direct contact with the body of the wearer and which is contacted first by the body fluids and exudate. A waterproof or water impervious layer, usually of polyethylene or the like, is frequently also used as a backing layer which covers the outer surface of the absorbent fibrous core and prevents the passage of the body fluids or exudate beyond the absorbe'nt fibrous core.
it is to be readily appreciated that if all the body fluids and exudates were to rapidly pass through the relatively non-absorbent, non-adherent hydrophobic facing sheet of the diaper and be absorbed and retained substantially completely by the inner absorbent fibrous core, the facing sheet would remain relatively dry. This would increase the absorptive effectiveness of the diaper and would decrease the incidence of diaper rash and related irritation which could be created by the presence of body fluids and exudates if they were permitted to remain in the facing in continual contact with the body of the wearer of the diaper.
The principal purpose and object of this invention is therefore to provide a facing material for absorbent products which is capable of rapidly passing the body fluids and exudates through to the inner absorbent core whereby the facing material remains relatively dry and thus possesses anti-rash and anti-irritation properties.
It has been discovered that such purpose and object, as well as other purposes and objects which will become clear from a reading of this disclosure, may be accomplished by 1) manufacturing the facing material in the form of a fibrous web made substantially completely of relatively non-absorbent, nori-adherent hydrophobic, synthetic fibers; (2) bonding the fibrous web into a bonded nonwoven fabric by means of a hydrophobic binder material; (3) applying a rewetting surfactant to the bonded nonwoven fabric; (4) increasing the bulk of the bonded nonwoven fabric without materially increasing the weight per square yard thereof; and then (5) using the bonded, bulked nonwoven fabric as the facing material for an absorbent product.
The present invention will be further described in greater detail by reference to the following specification and claims and the accompanying drawings wherein there is described and illustrated a preferred embodiment of the invention.
In the drawings,
FIG. 1 is a fragmentary, partially cutaway, perspective view of a portion of a diaper, representing a preferred embodiment of the absorbent products of the present invention; and
FIG. 2 is a diagrammatic, schematic showing of a process for manufacturing the absorbent products of the present invention.
With reference to the drawings and particularly FIG. 1 thereof, there is shown an absorbent product such as adiaper 10 which comprises a nonwoven fabric facing sheet 12, a centrally located highly absorptive fibrous body or core 14, and a waterproof or water impervious backing sheet 16, made of polyethylene or similar material.
The nonwoven fabric which is the basis of the facing sheet 12 may be made by any of the well-known processes for making such nonwoven fabrics. Typical of such nonwoven fabrics are the so-called *KEYBAK bundled rearranged nonwoven fabrics wherein the individual fibers are more or less predominantly oriented in one direction but are also reorganized and rearranged in predetermined, regularly repeating designs or patterns comprising a plurality of fabric openings and fiber bundles. Such fabrics are described in greater detail in U. S. Pat. Nos. 2,862,251, 3,025,585 and 3,033,721.
Another type of nonwoven fabric suitable as the facing sheet of the present invention is the so-called MASSLINN nonwoven fabric derived from carded fibrous webs wherein the individual fibers are predominantly oriented in one direction. Such fabrics are described in greater detail in U. S. Pat. Nos. 2,705,498, 2,705,687 and 2,705,688.
Still another type of nonwoven fabric suitable as the facing sheet of the present invention is the so-called isotropic nonwoven fabric wherein the individual fibers are disposed at random and are not predominantly oriented in any one direction. Such fabrics are described in greater detail in U. S. Pat. Nos. 2,676,363 and 2,676,364.
A still further type of nonwoven fabric suitable as the facing sheet of the present invention is the more recently developed rearranged nonwoven fabric described in greater detail in British Pat. No. 1,088,376.
The synthetic fibers which are used to make up the fibrous web are relatively non-absorbent and hydrophobic. Typical of such synthetic fibers are the polyester, acrylic, modacrylic, polyamide nylon, polyolefin, polyurethane spandex, polyvinylidene chloride saran, fluorocarbon, and like fibers.
The terms non-absorbent" and hydrophobic are, of course, relative terms and, as such, require definition. Such terms are defined in many ways but it is believed that one of the most commonly accepted forms is the percentage of water absorbed by the fibers at 70 F. and 65 percent relative humidity. As used herein, the terms non-absorbent and hydrophobic are intended to include those fibers having water absorbencies less than about 4% percent by weight and preferably less than about 1 percent by weight.
Another accepted form of determining, the lack of absorption desirable in the fibers of the present invention is the percent water of imbibition which is the water content of a fiber when brought to equilibrium from the wet side at 100 percent relative humidity and 70 F. Under such conditions, the percent of water imbibition should be less than about percent and preferably less than about 2 percent by weight.
In the following description, the polyester fiber will be used as the relatively non-absorbent, hydrophobic fiber to illustrate the invention but such is by way of example and is not limitative of the broader aspects of the present invention.
As used herein, the term polyester" conforms with the Federal Trade Commissions Rules and Regulations under the Textile Fiber Products Identification Act and is a manufactured fiber in which the fiber-forming substance is any long chain synthetic polymer composed of at least 85 percent by weight of an ester of a dihydric alcohol and terephthalic acid (p-HOOCC,H COOI-I).
Other fiber terms such as acrylic, modacrylic, rayon, nylon," olefin," etc., as used herein, are used as defined by Federal Trade Commisiions Rules and Regulations under the Textile Fiber Products Identification Act.
The most common polyester fiber used herein is polyethylene terephthalate derived from a reaction between ethylene glycol and terephthalic acid. Such a fiber is sold by various companies under various trademarks such as Dacron, Kodel, Encron, Vycron, Quintess, Trevira," Fortrel, Avlin,?. Blue C, etc.
The denier of the relatively non-absorbent, hydrophobic fibers may be selected from a relatively wide range of from about 1 denier to about denier, depending upon the needs and requirements of the particular situation. Preferably, however, a range of from about 1 /4 denier to about 3 denier has been found most desirable from a commercial viewpoint.
The weight of the fibrous web may be varied relatively widely depending on the uses for which it is intended. Weights as low as about 150 grains per square yard are useful for some purposes, whereas heavier weights up to about 1,000 grains per square yard are required for other uses. Within the more commercial fields, a range is preferred of from about 250 grains per square yard to about 550 grains per square yard.
In some uses and applications wherein the needs and requirements are not too rigorous, it is possible to in-- clude a minor percentage, up to about 25 percent by weight of the total weight of the fibrous web, of fibers which are not relatively non-absorbent or hydrophobic. Typical of such fibers are the natural and synthetic cellulosic fibers, such as cotton and rayon.
The fibrous web W may be manufactured by any desired apparatus (see FIG. 2) such as described or referred to previously, and is then forwarded, if so desired, through fibrous web reorganizing and rearranging apparatus 24 referred to hereinbefore. The fibrous web is preferably, however, reorganized and rearranged by passage through apparatus illustrated in FIGS. 7-l0 of U. S. Pat. No. 2,862,251 whereby the familiar fabric openings and fiber bundles of a typical KEYBAK bundled rearranged nonwoven fabric are obtained.
Although the present invention will be described with special emphasis on the use of a KEYBAK bundled rearranged nonwoven fabric as the facing sheet, such is for illustrative purposes and is not to be construed as limitative of the broader aspects of the present invention.
The fibrous web is then bonded into a bonded nonwoven fabric F in suitable web bonding apparatus 28 which may comprise spraying techniques, overall impregnation bonding techniques or intermittent print pattern bonding techniques, such as described in the patents relating to the manufacture of the so-called MASSLINN nonwoven fabrics.
Application of the bonding material may be accomplished, for example,.by any conventional saturation coating or impregnating apparatus, such as by having the fibrous web pass in rolling contact with an applicator roll 29 or the like having a suitably prepared surface and which dips into a trough or bath 30 containing a supply of the bonder material 31 which is transferred to the fibrous web. Nip rolls 32, 33 or other suitable devices may be used to control the amount of binder material which is added.
The binder material must naturally be inert, non-toxic, non-allergenic, and non-irritating to the skin of the user. It must have very little and preferably no affinity for water and specifically no affinity for body fluids and exudates or any other fluids with which it may come in contact in use. It should be used in an amount and in a fashion'as not to stiffen or reduce the softness of the fibrous web, either immediately or upon ageing. It should be colorless and odorless.
The binder material should be hydrophobic and water repellent and of the type which is water insensitive and which does not re-wet too readily. Typical of such binder materials are the solution or emulsion polymerized resins which are usually in the form of solid resin particles dispersed in a liquid which is normally water.
Suitable examples of such resins are the polyvinyl chlorides and particularly plasticized polyvinyl chloride; polyvinyl acetates and polyvinyl chloridepolyvinyl acetate copolymers; polyacrylates such as ethyl acrylates and other alkyl acrylates; polymethacrylates such as methyl methacrylate, ethyl methacrylate, etc.; polyacrylate copolymers such as ethyl acrylatemethyl methacrylate copolymers; polyvinyl chloridealkyl acrylate copolymers such as vinyl chloride-ethyl acrylate copolymers; polyvinyl acetate-alkyl acrylate copolymers such as vinyl acetate-methyl acrylate copolymers; polyurethanes; synthetic rubber latexes; etc.
The amount of binder material which is applied to the fibrous web may be varied within relatively wide limits. A range of from about 15 percent to about 45 percent by weight, based on the total weight of the bonded fibrous web is suitable, with a preferred range of from about 25 percent to about 35 percent by weight, based on the total weight of the bonded fibrous web.
The bonded nonwoven fabric F is then dried by any suitable drying apparatus 34, such as a series of rotating heated drying cans, or by passage through a heated drying chamber or oven. Elevated temperatures of from about 220 F. to about 330 F. are normally employed for the heating step which may also perform a curing function for the binder material, if necessary.
Subsequent to the drying step, the bonded nonwoven fabric F is impregnated in conventional coating or impregnating apparatus 36 with a surfactant having rewetting properties.
The surfactant may be anionic, cationic, or nonionic. Specific classes of suitable surfactants include: sodium and potassium salts of saturated fatty acids containing 5-18 carbon atoms; sodium alkyl sulfates containing 6-18 carbon atoms; sodium alkyl sulfonates containing 6-18 carbon atoms; sodium alkyl benzene sulfonates containing 6-18 carbon atoms; sodium l-methyl alkyl benzene sulfonates in which the methyl alkyl group contains 12-18 carbon atoms; sodium di-alkyl sulfosuccinates in which each group contains 4-12 carbon atoms; sodium polyoxyethylene ether alcohol sulfates in which the alcohol contains 12-18 carbon atoms; triethanolamine salts of fatty acids; alkyl amine hydrochlorides; alkyl trimethyl ammonium bromides; di-alkyl dimethyl ammonium chlorides; polyoxyethylene mono alkyl ethers in which the alkyl group contains 12 to 18 carbon atoms; polyoxyethylene nonyl phenyl ethers; methoxy polyoxyethylene decanoates and dodecanoates; etc.
Particular preferred species within the above-mentioned classes of surfactants include: anionic surfactants such as Aerosol OT (dioctyl sodium sulfosuccinate); Aerosol OS (isopropyl naphthalene sodium sulfosuccinate); Deceresol OS (sodium di-isopropyl naphthalene sulfonic acid); Emulgator K-30 (sodium alkyl C -C sulfonate); Triton X-405" (polyethylene glycol nonyl phenyl ether (40 moles ethylene oxide); l-lyamine (tertiary aryl dialkyl amine).
The surfactant must naturally be inert, non-toxic, non-allergenic, and non-irritating to the skin of the user. It should be used in an amount and in a fashion as not to stiffen or reduce the softness of the nonwoven fabric, either immediately or upon ageing. It should preferably be colorless and odorless and should not significantly reduce the wet or dry strength of the material to which it is applied.
Application of the surfactant may be accomplished by any conventional method such as by having the nonwoven fabric pass in rolling contact with a coating or impregnating roller 37 or the like, the surface of which has been suitably prepared and which dips into a trough or receptacle 38 containing a supply of the surfactant material 39 and transfers the same to the nonwoven fabric.
The amount of rewetting surfactant which is applied to the bonded nonwoven fabric F must be controlled within specified limits in order that just the right kind of rewetting properties and characteristics are obtained. It has been established that the addition of from about 0.1 percent by weight to about 2 percent by weight, based on the total weight of the bonded nonwoven fabric, is
suitable. Less than about 0.1 percent by weight does not create sufficient rewetting characteristics and more than 2 percent by weight causes the body fluids and exudates to tend to flow back into the facing sheet from the absorbent core whereby the facing sheet loses its relatively dry hand. Within the narrower aspects of the present invention, a range of from about 0.3 percent to about 1 percent by weight is preferred.
After the rewetting surfactant has been applied to the bonded nonwoven fabric, drying takes place in conventional drying apparatus 42 comprising a series of rotating heated drying cans or a heated oven maintained at an elevated temperature of from about 220 F. to about 300 F.
The bonded nonwoven fabric is then passed through suitable bulking apparatus 44 which may take the form of any conventional bulking of lofting apparatus presently available. An example of a typical bulking apparatus are the forms of apparatus described particularly in FIGS. l-5 of U. S. Pat. Nos. 2,765,513 and 2,765,514.
Such apparatus creates a crepe or a crimp in the nonwoven fabric whereby its bulk or loft is increased manyfold. The action is somewhat like a scuffing or piling action which fluffs up and crinkles the fibers of the nonwoven fabric, primarily in their direction of travel through the bulking apparatus. As a result of such scuffing and bulking action, the fibers no longer lay generally flat in substantially a single plane but are more erect and extend-in many cases from one surface to the other surface of the nonwoven fabric.
Such bulking action, however, basically also yields a compaction of the fibrous structure whereby the individual fibers are crowded together into a denser and more compact configuration. The nonwoven fabric is therefore drafted or elongated, such as by means of positively driven drafting rollers positioned at the exit of the bulking apparatus and capable of rotating at a desired speed whereby the nonwoven fabric is stretched and returned substantially to its original length. The loft of the nonwoven fabric, however, is maintained whereby the density or compaction of the fibers is reduced considerably.
The speed of the drafting rolls is so adjusted that they are capable of bringing the nonwoven fabric back substantially to its original length, or at least to within 5 percent or 10 percent thereof.
The retention of the high loft even after the drafting of the nonwoven fabric is due to many factors. The internal bonding and holding action of the binder material has been sufficiently disrupted during the bulking action whereby it does not hold the fibrous structure as it did previously to the bulking action and thus the bulk or loft remains. Additionally, the type of fiber used, and this is particularly true for the polyester species, possesses considerable resilience and spring-back and will tend to remain in its bulked and lofty condition and not to return to its flattened planar condition.
The increase in bulk or loft depends upon many processing factors such as the severity and intensity of the bulking action, the type of fibers present, the type and amount of binder material and surfactant applied, the degree of subsequent drafting action, etc. Under normal circumstances, increases in bulk or loft range from about 60 percent to about 340 percent. Couched in other terms, it may be stated, for example, that a fibrous web having an original thickness of about 6 or 7 mils may be increased in thickness to a range of from about 12 mils to 17 or 18 mils and even 25 mils or more, without substantial loss in length or increase in weight per square yard.
The thickness of the nonwoven fabric or the fibrous web may be determined by any suitable measuring apparatus, such as a Randall and Stickney Gauge made in Waltham, Mass.
The nonwoven fabric is forwarded to a product formation zone 48 whereat it is laminated with suitable absorbent structures as the facing sheet thereof, as desired or required. In the case of the absorbent product illustrated in FIG. 1, the absorbent structure comprises a heavier layer of absorbent fibers such as wood pulp, cotton and/or rayon, and a waterproof or water impervious backing sheet made of polyethylene, regenerated cellulose (cellophane), polyvinylidene chloride (saran), polyvinyl chloride, or other natural or synthetic material having like properties and characteristics.
The invention will be further illustrated in greater detail by the following specific examples. It should be understood, however, that, although these examples may describe in particular detail some of the more specific features of the invention, they are given primarily for purposes of illustration and the invention in its broader aspects is not to be construed as limited thereto.
EXAMPLE I An oriented card web weighing about 350 grains per square yard and comprising 100 percent Eastman Kodak Kodel polyethylene terephthalate polyester fibers having a denier of 1.5 and a staple length of 1% inches is used as the starting fibrous web material. The water absorbency of such fibers is about 0.4 percent.
This fibrous web material is passed through KEYBAK" rearranging apparatus such as illustrated in FIGS. 7-10 of U. S. Pat. No. 2,862,251, wherein the forming drum is provided with 225 holes per square inch, with each hole having a diameter of 0.045 inch, whereby the open area is about 37 percent.
The resulting rearranged fibrous web is then bonded with Rohm & Haas Rhoplex I-IA-8" which is essentially a self-crosslinking ethyl acrylate synthetic polymeric resin binder material. Drying takes place at a temperature of about 280 F. on a series of rotating heated dry cans, The amount of dry add-on of resin binder is approximately 30 percent by weight of the total weight of the bonded nonwoven fabric.
The bonded nonwoven fabric is then treated with American Cyanimids Aerosol OT" (dioctyl sodium sulfosuccinate) in a saturation impregnating bath and is dried at a temperature of about 260 F. on a series of rotating heated drying cans. The amount of dry add-on of the surfactant is about 0.5 percent by weight rf the total weight of the bonded, surfactant-treated nonwoven fabric.
The bonded, surfactant-treated nonwoven fabric is then bulked in apparatus illustrated in FIGS. 1-5 of U. S. Pat. Nos. 2,765,513 and 2,765,514 and then passed through the nip of rotating drafting rolls, the speed of which is so adjusted as to bring the length of the nonwoven fabric back to within 5 percent of its length prior to bulking. The thickness of the nonwoven fabric prior to bulking is about 7 mils. Subsequent to bulking, the thickness of the nonwoven fabric is about 17 mils which represents an increase in bulking or loft of about 143 percent, with a decrease in length of only about 5 percent.
The bulked, bonded nonwoven fabric is then laminated with a heavier absorbent core of comminuted wood pulp fibers which is backed up with a 1- mil polyethylene water-impervious film. The resultant composite absorbent product is useful as a disposable diaper, or as an underpad, a surgical dressing, or a compress, and is capable of absorbing and retaining substantial amounts of body fluids and exudates, while presenting a relatively dry, non-absorbent, non-adherent, hydrophobic surface to the body of the wearer.
EXAMPLES II-IV The procedures of Example I are followed substantially as set forth therein except that the relative speeds of the fast and slow rolls of the bulking apparatus are varied as to provide for changes in the increase of the bulking effect. The original thickness of 7 mils, rather than being increased to 17 mils, as in Example I, is increased to (II) 12 mils, (III) 18 mils, and (IV) 25 mils, representing increases in loft and bulk of (II) 71 percent, (III) l57'percent, and (IV) 258 percent, respectively. All three bulked bonded nonwoven fabrics are found suitable as facing materials on diapers, sanitary napkins, surgical dressings, underpads and compresses.
EXAMPLES V'-VIII The procedures of Example I are followed substantially as set forth therein except that the dry add-on of the surfactant is changed from 0.5 percent as in Example I to (V) 0.2 percent, (VI) 1.0 percent, (VII) 1.5 percent, and (VIII) 5 percent by weight. Results comparable to those obtained in Example I are obtained for the first three absorbent products but it is noted that the fourth absorbent product wherein 5 percent of surfactant is applied, there is a tendency for .the body fluids and exudate to wet back from the absorbent fibrous mass into the facing sheet whereby it does not remain as dry as desired.
EXAMPLES IX -XIV The procedures of Example I are followed substantially as set forth therein except that the following fibers are used to replace the polyester fibers of Example I: (IX) polyamide nylon 66 (hexamethylene tetramine-adipic acid), water absorbency 4 percent; (X) polyamide nylon 610 (hexamethylene tetraminesebacic acid), water absorbency-4percent; (XI) polyamide nylon 6 (caprolactam), water absorbency- 4 percent; (XII) polypropylene, water absorbency, 0.1 percent; (XIII) Acrilan acrylic fiber having more than percent by weight of acrylonitrile units, water absorbency, 1.5 percent; and (XIV) Dynel modacrylic fibers containing between 35 percent and 85 percent by weight of acrylonitrile units, water absorbency, 0.4 percent. The results are generally comparable to those obtained in Example I. The absorbent products containing the polypropylene fibers are particularly non-absorptive with the water of imbibition being only about 0.1 percent.
EXAMPLES XVXVIII The procedures of Example I are followed substantially as set forth therein except that the ethyl acrylate resin binder of Example I is replaced by: (XV) plasticized polyvinyl chloride; (XVI) polyvinyl acetate; (XVII) polyurethane; and (XVIII) vinyl acetate-butyl acrylate copolymer. The results are comparable to those obtained in Example I.
EXAMPLES XIX-XXIII The procedures of Example I are followed substantially as set forth therein except that the rewetting surfactant used rather than being Aerosol OT as in Example I is: (XIX) Aerosol OS (isopropyl naphthalene sodium sulfosuccinate); (XX) Deceresol OS (sodium di-isopropyl naphthalene sulfonic acid); (XXI) Emulgator K-30 (sodium alkyl C -C sulfonate); (XXII) Triton X-405 (polyethylene glycol nonyl phenyl ether (40 moles ethylene oxide); and (XXIII) Hyamine (tertiaryaryl dialkyl amine).
EXAMPLES XXIVXXVI The procedures of Example I are followed substantially as set forth therein with the exception that the fibrous web used is not an oriented rearranged card web as in Example I but is: (XXIV) an oriented card web which has not been rearranged and in which 25 percent of the polyester fibers are replaced by 1.5 denier, 1 9/16 inch staple length rayon fibers, water absorbency, 11 percent; (XXV) a 550-grain weight allpolyester oriented card web; and (XXVI) a 450-grain weight all-polyester fiber isotropic fibrous web. The results are generally comparable to those obtained in Example I.
EXAMPLES XXVIl-XXVIII The procedures of Example I are followed substantially as set forth therein except that the Kodel polyester fibers of Example I are replaced by (XXVI!) Fortrel" (Fiber Industries) and (XXVIII) Dacron (Du Pont) polyethylene glycol terephthalate polyester fibers are used. The water absorbencies of such fibers are both 0.4 percent. The results are comparable to those obtained in Example I. The water of imbibition of such fibers is less than about 2 percent.
Although the present invention has been described and illustrated with specific regard to particular embodiments thereof in the preceding examples, such is not to be construed as limitative of the broader aspects of the inventive concept, except as defined and limited by the appended claims.
What is claimed is:
1. A method of manufacturing an absorbent product having excellent absorption and retention capacity for body fluids and exudates but capable of maintaining a relatively dry surface during such absorption and retention comprising: (1) forming a fibrous web of overlapping, intersecting, relatively non-absorbent hydrophobic fibers; (2) bonding said fibers with a hydrophobic, water repellent, water insensitive binder aterial which d s not rewet t 0 re dil to f rm a bnd nonwover f abric; (3) coal ling s id onde nonwoven fabric with from about 0.3 percent to about 2 percent by weight, based on the total weight of said bonded nonwoven fabric, of a surfactant having rewetting properties; (4) compacting the bonded nonwoven fabric whereby the individual fibers are crowded together into a denser and more compact configuration; elongating the compacted, bonded nonwoven fabric whereby the bonded nonwoven fabric is returned to within about 10 percent of its original length prior to compacting and elongating and the bulk of said bonded nonwoven fabric is increased from about 60 percent to about 340 percent without materially increasing the weight per square yard thereto; and (5) combining said bonded, bulked nonwoven fabric with an absorbent fibrous body into a laminated absorbent product having excellent absorption and retention capacity for body fluids and exudates but capable of maintaining a relatively dry surface during such absorption and retention.
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|U.S. Classification||604/366, 604/372, 604/373, 604/379, 604/375, 604/371|