US2905568A - Method and apparatus for manufacturing an absorbent product - Google Patents

Description

Sept. 22, 1959 A. A. BURGENI 2,905,568

METHOD AND APPARATUS FOR MANUFACTURING AN ABSORBENT PRODUCT Filed Aug. 16, 1956 BY @lm T ML,

ATTO RN EY Patented Sept. 22, 1959 METHUD AND APPARATUSTFOR MANUFACTUR- ING AN ABSORBENT PRODUCT AlfredA. Burgeni, Short Hills, NJ., assignor to Personal Products Corporation, a corporation of New vJersey Application August 16, 1956, Serial No. 604,515 6 claims. (cl.117-11) This invention relates to absorbent brous bodies and to methods and apparatus for making them and, more particularly, is concerned with absorbent fibrous bodies which are especially suited for use as absorbent components in sanitary napkins, surgical dressings, compresses, disposable diapers, hospital underpads and other products designed to absorb uids.

Products designed to Iabsorb iuids generally contain as a principal component thereof an absorbent pad or core to absorb the fluids. These pads or cores are normally made of layers of loosely compacted, absorbent fibers, such -as carded cotton webs, air-laid cellulosic fibrous webs, comminuted wood pulp bats, or like materials which are highly absorbent, fluffy and porous. `Unfortunately, these loosely compacted, brous absorbent bodies posses numerous disadvantages, notably low cohesive strength, poor shape and volume stability, low forces of capillary attraction, low fluid retentivity and low absorptive capacities under conditions of use.

For example, comminuted wood pulp bats which are particularly suitable as absorbent components because of their highly absorbent properties, low cost and commercial availability, are Very Weak structurally and possess low cohesive stability, whereby they tend to fall iapart too readily under stress.

Additionally, these comminuted wood pulp bats, as well as cotton fibrous webs, do not possess shape and volume stability to any marked degree and quickly become deformed and distorted upon the application of slight forces or stresses.

Furthermore, the uid retentivity of such highly porous, fibrous absorbent bodies is not sufficiently great and, consequently, fluids which should be retained therein are squeezed out relatively easily by the application of pressures arising `from normal usage of the article.

Moreover, these fluffy, porous, absorbent fibrous cornponents possess low capillary forces because of their loosely compacted structure and, when a fluid is deposited on its surface, saturation conditions are reached very quickly at the site of immediate application. At the same time, however, the adjacent portions remain relatively unsaturated and in some instances dry due to the low capillary forces of the fibrous body and consequently a highly localized uid condition is obtained.

It is therefore seen that, although absorbent fibrous bodies have been manufactured in the past and have met with some commercial success, there still remains a considerable field for improvement toward a superior product.

In copending application Serial Number 587,015, filed on May 24, 1956, there are disclosed methods of manufacturing improved absorbent fibrous bodies with possess relatively high cohesive stability, good shape and volume stability, high forces of capillary attraction, good fluid retentivity and high absorptive capacity under conditions of use and which are especially suited for use as absorbent components in sanitary napkins, surgical dressings, compresses, disposable diapers, hospital underpads and other products designed to absorb fluids.

More specifically, the methods disclosed Yin said copending application comprise applyingl controlled amounts ofmoisturetothesurface or surfaces of a loosely compacted, -absorbent Ifibrous body having relatively low cohesive strength, relatively poor shape and volume stability, relatively low limits whereby there is formed, in situ, a paper-like, densiiied, highly compacted, cellulosic fibrous layer integral Iwith the loosely compacted, fibrous absorbent b ody andpossessing relatively high cohesive strength, relatively good shape and volume stability, relatively high fluid retentivity and relatively high capillary forces.

Such a densitied, compacted layer, in addition to improving the cohesive strength, shape and volume stability, fluid retentivity and capillary forces of the absorbent body, also increases its fluid storage capacity during conditions ofr use, minimizes lateral spreading or vertical draining (strike-through) and, in general, more desirably controls the reception, absorption `and retention of iluids deposited thereon.

The methods disclosed in said application for forming such `a compacted l-ayer have beenfound generally satisfactory, but it has been observed that the controlling of the amounts of processing liquid to be applied to the absorbent fibrous body is often quite difficult. This is particularly true lwhen smaller amounts, say, on the order of about 0.0005 cc. of water are applied per square centimeter of web surface. Additional difficulty arises whenever it is desired to control the direction of the supply of liquid so `that only specific portions or areas of the absorbent fibrous body are wetted.

It is therefore a principal objective of the present invention `to prov-ide -methods of forming paper-like, densiiied, highly compacted, cellulosic fibrous layers integral with loosely compacted, absorbent fibrous bodies 1n which better control is exercised over the amounts of the processing liquid to be applied and over the direction of the liquid to the specific-areas to which the processing liquid is to be applied.

These objectives and-others which Will become clear hereinafter are obtained by providing a fabricated transfer web which is wetted-to av predetermined concentration and is then-positioned-between-theabsorbent fibrous bodyand the pressure-applying means whereby the processing liquid Ynecessary to `form the dense compacted layeris transferred from the transfer web to the absorbent fibrous bodyduring the .application of pressure.

In the accompanying drawing and the following speciiication there isl illustrated Iand described a preferred method of carrying out the present invention, but it is to be understood that the inventive concept is not to be construed as limited thereto except as defined by the spirit of the invention and determined by the scope of the appended claims. Referring to the drawing. The figure is a schematic showing of apparatus suitable for carrying out the methods of the present invention.

In the embodiment of the invention shown in the drawing, an absorbent-brousflbody 9 is guided so as to pass under a roller 10 which is capable of controllably applying a predetermined pressure thereto to compact and, if desired, emboss the same. A `reservoir or tank 11 containing an aqueouspprocessing-liquid 12'is positioned adjacent to the yroller 10 and a transfer web 13 is guided so as to be dipped into the processing liquid by a driving roller 14 and .guide- rollers 15,15 and 15 so-as to pick up the 'processing liquid.4 The saturated transfer web 13 is' then guided between the rolls of a squeeze roll system 1'6 wherein the fluid 'content thereof is adjusted tothe desired take-up amount. The transfer web is then guided by rollers `17, 18 'and 1.9fso as to be inserted between the absorbent fibrous body`9 and the pressure roller 10. The web travels with the absorbent fibrous body for a short distance, and then leaves it, preferably at an obtuse angle. No sticking or adhering of the compacted layer to the transfer web is noted and there is no tendency of the lesser compacted portions of the Vlayer to separate from the absorbent fibrous body.

The angle at which the transfer web 13 leaves the treated absorbent vfibrous body 9 is important, and although the nature of the transfer web may be such and the conditions of moisture, application of pressure, etc., may be so selected that an acute angle of less than 90 may be employed at roller 19, an obtuse angle of greater than 90 and up to 180 is customarily used. Substantially the same eifect is realized by the use of a roller at roll 19 which possesses a relativelysmall diameter Where- Iby the transfer web 13 may be removed from the absorbent fibrous body 9 quickly by being peel sharply there- `from in a small radius of curvature.

The particular liquids which are applied in the tank 11 are characterized by their ability to produce or contribute to a permanent set of the deformation achieved in compressing and/or embossing the absorbent body. 'Ille object of the liquid setting agent is to stabilize the compressive deformation and to improve the coherence of the absorbent body. In the absence of such liquid setting agents, it is necessary to apply much higher pressures to set the compressed absorbent body. Moreover, dry compressed absorbent bodies remain substantially non-coherent and the set is largely lost in subsequent contact with water or other swelling agents.

The setting mechanism in the described operation is that of forming bonds between the wetted and compressed fibers which is a well-known and fundamental reaction in the process of paper making. Water is the most convenient and economical bonding iiuid for cellulosic absorbent bodies but it may be partially or completely replaced by other strongly polar uids. If desired, the stabilizing effect of the water bond can be enhanced by well-known textile sizing and finishing agents, such as natural and synthetic gums including starches, dextrins, casein, methyl cellulose, carboxymethyl cellulose, etc., thermoplastic and thermo-setting resins including polyvinyl acetate, polyvinyl chloride, copolymers thereof, etc., waxes, etc. These auxiliary processing agents are preferably used in aqueous solution, suspension or dispersion.

The transfer webs may be woven, knitted, braided or felted fabricated materials made from natural and/or synthetic iibers, monolilaments, multilaments and staple yarn and even of glass or metallic wires in conjunction with water absorbable materials. Fabrics of high mechanical resistance made from nylon, Orlon, Saran, saponied acetate rayon, and other exand abrasion-resistant synthetic materials may beused. Alternatively, such synthetic materials may be used in blends with naturally occurring yarns. For example, in the case of a woven fabric, the warp threads may be cotton and the filling or weft threads may be nylon, such as when longitudinal lines are to be embossed into, the absorbent body.

If increased stretchability is desired in the transfer web, it may be of knitted or specially woven construction such as an elastic Helencafwoven fabric. The transfer web may contain rubber threads, such as Lastex, or the like. A fair degree of stretchability may also be obtained with mercerized-shrunk, natural cellulosic fabrics or by bias cutting of woven cloth. Y

It is not essential that the transfer webrhave the same width as the absorbent fibrous body. For example, if it is desired that a narrow, dense, compacted skin be formed on the absorbent fibrous body, then Ya transfer web of such narrower width is satisfactorily employed. In the same way, if a striped effect is desired, then a plurality of narrow transfer` webs is used. `In Ythe same way, any desired arcuate or angular effect may be obtained by forming the transfer web in the size and shape desired. These effects may be further enhanced by using` different processing liquids on a plurality of transfer webs. For example, three narrow transfer webs may be used with the outer transfer webs containing water repellent sizes and the innerI transfer web containing a reinforcing, hydrophilic size. Similarly, various colored effects may be obtained by the use of different dyes in the several transfer webs.

It is also to be appreciated that the transfer web itself is capable of embossing the absorbent fibrous body. For example, a ribbed effect may be obtained by using a twill cloth for the transfer web. Actually, any type of fabricated material having a pronounced contoured surface can be used to create a complementary effect in the absorbent fibrous body. Wire screening of a size about 14-18 mesh per inch, when combined with aqueous absorbent material, provides an excellent embossing means, either used Warpwise or on the bias to create lbetter flexibility. r

The absorbent fibrous bodies of this invention contain cellulosic fibers, such as comminuted wood pulp fibers, cotton linters, or the like, which have a fiber length less than one-quarter of an inch and which, in the presence of moisture and pressure, are capable of forming a relatively dense, more or less coherent, relatively stable structure formed as a result of interliber bonds between the moistened and compressed fibers similar to the bonds between bers in paper. Cellulosic bers, such as Wood pulp fibers and cotton linters, are preferred in making the fibrous bodies of this invention because they readily form such interflber bonds, when moistened and compressed. Such fibers are additionally commercially desirable inasmuch as they are inexpensive, readily available and highly absorbent. Other fibers capable of developing interber bonds, similar to the bonds between fibers in paper in the presence of moisture and pressure may also be used. In addition, blends of natural or synthetic fibers, such as silk, wool, linen, nylon and cellulose acetate bers, may be used in combination with the fibers capable of forming interber bonds in the presence of moisture and pressure. v

It is believed that the formation of the densilied skin is due to the formation of bonds between contacting moistened fibers, which bonds are similar to the bonds between the fibers in paper. By the proper selection of the amount of moisture applied to the fibers and by the proper selection of the degree of compression imposed, the properties of the densified skin may be varied, as desired or required. The thickness, density, strength and other characteristics ofthe densied skin also depend upon the uniformityby which the moisture is applied, the depth to which it penetrates and the degree to which the fibers are compressed.

The amount of moisture used may vary from about 0.0005 to about 0.03 cc. of water or aqueous liquid per square centimeter of surface depending upon the thickness of the absorbent fibrous body, the thickness of the paper-like dense compacted skin desired, with the lesser amounts of moisture being used for thinner webs and yielding extremely thin papery skins and the greater amounts of moisture being used for thicker brous bodies and yielding skins of a greater thickness.

Within the more commercial aspects of the present invention, however, it has been found that a range of from about 0.001 to about 0.004 cc. of water per square centimeter of fibrous body surface has been found economically desirable for fibrous bodies having a thickness of from about V1/2 to about l centimeter.

The upper limits of these ranges are not critical and greater amounts of moisture may be used Whenever thicker fibrous bodies are employed or when thicker skins are desired. As a matter of fact, suiiicient moisture may be applied to completely penetrate the librous body whereby it may be compacted and densiied fhfvushsuf its .Complete veluwe.

tures of the invention,

through the nip of an The amounts of pressure to be applied .to the absorbent fibrous bodies through the transfer webs may be varied .from as little as ,about to about'1000 or more pounds per square inch with the commercially preferable range `extend-ing from about to about 100 pounds per square inch for fibrous -bodies having a thickness of from about 1/z to about 1 centimeter.

The invention willbe further illustrated in greater detail by the following specific examples. It should beunderstood, however, that although theseexamples may de- -scribe in-particulardetail some of the more specific fea- `they are given primarily for purposes of illustration `and the invention in itsibroader aspeotsis not` to be construed as limited thereto.

Example I `fibers less than 1A inch in length. This absorbent body is 68 mm. wide,'5,.9 mm. thick, weighs 0.031 gram per cubic centimeter and is loosely compacted, non-coherent and extremely porous.

The. absorbent fibrous body with the resin impregnated cotton transfer web covering its upper face is passed steel rolls. The pressure in the embossing device is set to cause a transfer of processing liquid from the transfer web into the absorbent fibrous body amounting to about 0.0059 gram per square centimeter based on the area of lthe absorbent fibrous body prior to embossing. The

transfer of processing liquid based on the weight of the absorbent fibrous body is 31% resin solids is 1.8%.

After emerging from the embossing device, the transfer web is pulled' away from the absorbent fibrous body over a small roller at an obtuse angle of about 150. The separation is satisfactory and the absorbent fibrous body does-not tear and the fiber alignment is not disarranged.

The dried web shows a sharp but shallow imprint of the embossing pattern. The treated face is `covered with a thin, coherent, paper-like skin of excellent abrasion resistance and strength which stabilizes the absorbent fibrous body. The structure of the absorbent body on the other side away from the transfer web remains substantially loosely compacted, non-coherent and highly porous.

and the transfer of the Example II The procedures set forth in Example I are carried out vsubstantially as set forth therein exceptl that a fHelenca elastic nylon fabric is used as the transfer web instead of the cotton print cloth. The impregnated fabric is squeezed out `to adjust the take-up to 108% and is then superimposed on an absorbent fibrous body'havingthe same bulk weight, width and thickness as that of Example I.

The embossing operation is carried out and causes a transfer of 32% processing liquid from the transfer web to the absorbent fibrous body, based on the dry weight of the latter. The transfer web separates from the embossed fibrous body without tearing or disrupting the liber alignment of thelatter. The dried absorbent body resembles the product of Example I except that the grooves are .considerably .deeper. The treated side shows the characteristic formation of a dense, coherent, paper-like, compacted skin which stabilizes the absorbent brousbody.

web is squeezed out to adjust embossing device consisting of two v6 :Example-'III Twotransferwebs-referred to below as A andB are employed-in the following process in which an embossing hydrophilic skin and a substantially smooth, waterrepellentA skin are developed' simultaneously on the opposite faces of anon-coherent, absorbent fibrous body. This body comprises-bleached cotton linters having an average fiber-length 'less than 1r'inch, is10.7-rnm. thick and has abulk density of 0.034-'gram per centimeter.

Transfer web Avisa coarse leno lnetting weighing 224 grams per square'meter. Transfer web -B is a smooth, densely woven twill fabric made from a mixture of nylon, rayon and cellulose acetate and vweighs 305 grams per square meter. Transfer tweb 'A is impregnated with water ,and squeezed out to a take-up of about 141%. Transfer web B is impregnated with a commercial waterrepellent wax dispersion and squeezed out to a take-up of about 82.6%.

tively.

sides'with a dense, coherent,gcompacted skm, one bemg other being hydrophobic and water-repellent. Between these skins is a highly porous'layer of substantially unbonded fibers accounting for 95% of the total thickness of the product.

.Example IV Two `endless transfer webs of bleached cotton `gauze having 44 X'3'6 strands of 60's yarnper square inch are moistened with water by spraying. The take-up-is about based on the dry weight of the gauze. One of these transfer webs is placed on top and the other placed underneath an absorbent fibrous body of disintegrated wood pulp 7.8 mm. thick and'having'a bulk density of 0.031 gram per cubic centimeter. The absorbent wood pulp body is sandwiched between the wetted gauze strips and then is compressed in a mangle containing two rubberized steel rolls. -In this compression, 10% moisture,v based on the. dryweight of the absorbentfibrous wood pulp body, is takenup bythe-latter. The transfer webs separate from .the compressed product without disrupting the alignment of fibers therein. The dried product is covered on both sides with a thin skin which, owing to the imprint of the vgauze, isffabriclike -in appearance. These skins greatly improve Vthe textile strength and abrasion resistance of the product and prevent the shedding of fibers in the handling thereof.

Example V A longitudinal channel providedwith laterally spaced peaks and valleysis embossedinto an absorbent fibrous body of disintegrated lwood pulp. The processing conditions are as follows: the absorbent fibrous body is 68 mm. wide, 5.9 mm. thick'and weighs 0.031 gram per cubic centimeter; the transfer web is cotton tricot weighing 214 grams per square meter and a width of 26 mm.; the ernbossing roll is a spur gear to lform the laterally spaced peaks and valleys; and the setting solution is an aqueous commercial dextrnxsuspension of approximately 6.7% solids.

The transfer web isimpregnated with the processing liquid and squeezed out to Ya take-up of about "123% based lon the .dry weight of'the'web. vThe absorbent fibrous body, with thenarrower transfer web covering only the center portion of thefibrousbody surface, is

7 passed through the embossingV device. The pressure exerted by the latter is adjusted to transfer about 0.005 gram of liquid per square centimeter of the embossed channel.

The dried product contains an embossing channel of bonded fibers. This bonded effect is particularly distinct in the areas of the lateral grooves created by the teeth of the embossing spur gear. Outside the channel boundaries and in the spaced peaks between the valleys, the structure of the product changes abruptly into that of a non-coherent, loosely compacted fiber mass in which the high porosity and softness of the original absorbent fibrous body is fully preserved.

Example VI A non-woven fabric consisting of a fiber blend of 75% rayon and 25% cotton is made as follows: four layers of card web, each weighing 175 grains per square yard, are sandwiched between two Helenca woven nylon fabrics constituting the transfer webs. These transfer webs are impregnated with an aqueous dispersion of 20% polyvinylaeetate and 2.5% dibutoxyethyl phthalate and then are squeezed out to a take-up of about 100% based on the dry weight of the transfer webs. The card web, with the transfer webs covering its top and bottom faces is then run between nip rolls wherein the pressure of the rolls transfers 120% fluid, based on the dry weight of the card web. The resulting non-woven fabric is bonded substantially throughout its total thickness.

It is to be noted that two separate circuits', 4are required by the two transfer webs. This isV accomplished by merely duplicating apparatus, treating tanks and pressure rollers on opposite sides of the absorbent fibrous body being treated.

Example VII 'Ille procedures set forth in Example VI are carried out substantially as set forth therein with the exception that cotton twill fabrics are used instead of Helenca fabrics. The embossed imprint of the twill construction enhances the fabric-like appearance of the bonded absorbent fibrous body.

Example VIII The procedures set forth in Example VI are repeated substantially as set forth therein with the exception that only one transfer web is used to apply the resin dispersion. The opposite face of the absorbent fibrous body is left untreated. The resulting non-woven fabric possesses one bonded surface and one unbonded surface which possesses a distinct nap consisting of partially unbonded fibers. The presence of this nap imparts a degree of heat insulation and softness normally not associated with woven fabrics. q f

From the above, it is seen that loosely compacted adsorbent brous bodies, which possess relatively low cohesive strength, relatively poor shape and volume stability, relatively low fluid retentivity, and relatively low capillarity are converted to bodies possessing a relatively dense, compacted, coherent skin which creates sufficient strength, shape and volume stability, liuid retentivity, and capillarity as to render the resulting structure especially suited and highly desirable for use as absorbent components in surgical dressings, sanitary napkins, compresses, disposable diapers, hospital underpads, and other products designed to absorb fluids.

It is, of course, realized that various modifications and changes may be made within the spirit of the invention. For example, various materials such as bactericides, fungicides, dyestuffs, softening agents, sizing materials, adhesives, and the like, may be included inthe water used for moistening the surfaces of the webs. These processes reflect the well-known possibilities of mechanically modifying paper to obtain desired results or effects.

While I have shown and described what I believe to be preferred embodiments of my invention in the matter of simplicity and durability of construction, it will be appreciated that the details of such construction may be more or less modified within the scope of the claims without departure from the principles of construction or material sacrifice of the advantages of the preferred designs.

Irclaim:

l. A method of producing an absorbent fibrous body suitable for use as an absorbent component in absorbent products which comprises moistening a transfer web with au aqueous processing liquid; positioning said moistened transfer web on a highly porous, loosely compacted, celulosic absorbent fibrous body having relatively low cohesive strength, relatively low capillary forces, relatively poor shape and volume stability, and relatively low fluid retentivity; applying a deformation producing pressure to said absorbent fibrous body through said transfer web thereby transferring aqueous processing liquid from said transfer web to said highly porous, loosely compacted, cellulosic absorbent fibrous body; and simultaneously compressing the same in the presence of the aqueous processing liquid to produce a permanent set of the deformation resulting from the application of pressure whereby there is formed in situ therefrom and integral therewith, a paper-like densified, compacted cellulosic fibrous layer having relatively high cohesive strength, relatively good capillary forces, relatively good shape and volume stability and relatively high fluid retentivity.

2. A method of producing an absorbent fibrous body suitable for use as an absorbent component in absorbent products which comprises moistening a transfer web with an aqueous processing liquid, said web having a patterned surface, positioning said moistened transfer web on a highly porous, loosely compacted, cellulosic absorbent fibrous body having relatively low cohesive strength, relatively low capillary forces, relatively poor shape and volume stability, and relatively low fluid retentivity; applying a deformation-producing pressure to said absorbent fibrous body through said transfer web thereby transferring aqueous processing liquid from said transfer web to said highly porous, loosely compacted, cellulosic absorbent flbrous body; and compressing the same in the presence of the aqueous processing liquid to produce a permanent set of the deformation resulting from the application of pressure whereby there is formed in situ therefrom and integral therewith, a paper-like densifed, compacted cellulosic fibrous layer having surface characteristics similar to the patterned surface of said transfer web and having relatively high cohesive strength, relatively good capillary forces, relatively good shape and volume stability and relatively high fluid retentivity.

3. A method of producing an absorbent fibrous body suitable for use as an absorbent component in absorbent products which comprises moistening two transfer webs with an aqueous processing liquid; positioning one of said moistened transfer webs on the top surface and the other transfer web on the bottom surface of a highly porous, loosely compacted, cellulosic absorbent fibrous body having relatively low cohesive strength, relatively low capillary forces, relatively poor shape and volume stability, and relatively low fluid retentivity; applying a deformation-producing pressure to said absorbent fibrous body through said transfer webs thereby transferring aqueous processing liquid from said transfer webs to said highly porous, loosely compacted, cellulosic absorbent fibrous body; and compressing the same in the presence of the aqueous processing liquid to produce a permanent set of the deformation resulting from the application of pressure whereby there is formed in situ therefrom and integral therewith on the top and bottom surfaces of said absorbent, fibrous body a paper-like densified, compacted cellulosic fibrous layer having relatively high cohesive strength, relatively good capillary forces, relatively good shape and volume stability and relatively high uid retentivity.

4. A method of producing an absorbent fibrous body suitable for use as an absorbent component in absorbent products which comprises moistening first a transfer web with an aqueous hydrophobic processing liquid; meistening a second transfer web with an aqueous hydrophilic processing liquid, positioning said first transfer web on one surface of and said second transfer web on the opposite surface of a highly porous, loosely compacted, cellulosic absorbent brous body having relatively low cohesive strength, relatively low capillary forces, relatively poor shape and volume stability, and relatively low uid retentivity; applying a deformation-producing pressure to said absorbent fibrous body through said transfer webs thereby transferring aqueous processing liquids from said transfer webs to said highly porous, loosely compacted, cellulosic absorbent brous body; and compressing the same in the presence of the processing liquids to produce a permanent set of the deformation resulting from the application of pressure whereby there is formed in situ therefrom and integral therewith on one surface of said brous body a hydrophobic and on the other surface a hydrophilic paper-like densiiied, compacted cellulosic brous layer having relatively high cohesive strength, relatively good capillary forces, relatively good shape and volume stability and relatively high fluid retentivity.

5. Apparatus for producing an absorbent fibrous body suitable for use as an absorbent component in absorbent products which comprises means for moistening a transfer web with an aqueous processing liquid; means for positioning said moistened transfer web on a highly porous, loosely compacted, cellulosic absorbent fibrous body having relatively low cohesive strength, relatively low capillary forces, relatively poor shape and volume stability, and relatively low fluid retentivity; compression means for applying a deformation producing pressure to a portion of the area of said absorbent fibrous body through said transfer web sucient to cause the transfer of aqueous processing liquid from said web to said body and to form in situ in said area an integral paper-like, densified, compacted cellulosic fibrous layer having relatively high cohesive strength, relatively good capillary forces, relatively good shape and volume stability and relatively high fluid retentivity, andrmeans for separating said transfer web from said absorbent brous body.

6. Apparatus for producing an absorbent fibrous body suitable for use as an absorbent component in absorbent products which comprises means for moistening a transfer web with an aqueous processing liquid; means for positioning said moistened transfer web on a highly porous, loosely compacted, cellulosic absorbent fibrous body having relatively low cohesive strength, relatively low capillary forces, relatively poor shape and volume stability, and relatively low fluid retentivity; compression means for applying a deformation producing pressure to a portion of the area of said absorbent fibrous body through said transfer web suicient to cause the transfer of aqueous processing liquid from said web to said body and to simultaneously form in situ in said area an integral, paper-like, densified, compacted cellulosic fibrous layer having relatively high cohesive strength, relatively good capillary forces, relatively good shape and volume stability and relatively high uid retentivity, and means for separating said transfer web from said absorbent fibrous body.

References Cited in the le of this patent UNITED STATES PATENTS 10,458 Overend Jan. 24, 1854 1,942,693 Grapp Ian. 29, 1934 2,545,952 Goldman Mar. 20, 1951 2,589,765 Berglund Mar. 18, 1952 2,668,787 Schram Feb. 9, 1954 2,698,574 Dougherty et al. Ian. 4, 1955 FOREIGN PATENTS 320,477 Great Britain Oct. 17, 1929

Claims (1)

1. A METHOD OF PRODUCING AN ABSORBENT FIBROUS BODY SUITABLE FOR USE AS AN ABSORBENT COMPONENT IN ABSORBENT PRODUCTS WHICH COMPRISES MOISTENING A TRANSFER WEB WITH AN AQUEOUS PROCESSING LIQUID; POSITIONING SAID MOISTENED TRANSFER WEB ON A HIGHLY POROUS, LOOSELY COMPACTED, CELULOSIC ABSORBENT FIBROUS BODY HAVING RELATIVELY LOW COHESIVE STRENGTH, RELATIVELY LOW CAPILLARY FORCES, RELATIVELY POOR SHAPE AND VOLUME STABILITY, AND RELATIVELY LOW FLUID RETENTIVITY; APPLYING A DEFORMATION PRODUCING PRESSURE TO SAID ABSORBENT FIBROUS BODY THROUGH SAID TRANSFER WEB THEREBY TRANSFERRING AQUEOUS PROCESSING LIQUID FROM SAID TRANSFER WEB TO SAID HIGHLY POROUS, LOOSELY COMPACTED, CELLULOSIC ABSORBENT FIBROUS BODY; AND SIMULTANEOUSLY COMPRESSING THE SAME IN THE PRESENCE OF THE AQUEOUS PROCESSING LIQUID TO PRODUCE A PERMANENT SET OF THE DEFORMATION RESULTING FROM THE APPLICATION OF PRESSURE WHEREBY THERE IS FORMED IN SITU THEREFROM AND INTEGRAL THEREWITH, A PAPER-LIKE DENSIFIED, COMPACTED CELLULOSIC FIBROUS LAYER HAVING RELATIVELY HIGH COHESIVE STRENGTH, RELATIVELY GOOD CAPILLARY FORCES, RELATIVELY GOOD SHAPE AND VOLUME STABILITY AND RELATIVELY HIGH FLUID RETENTIVITY.

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